WO2023098311A1 - 一种电化学装置和电子装置 - Google Patents

一种电化学装置和电子装置 Download PDF

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Publication number
WO2023098311A1
WO2023098311A1 PCT/CN2022/125071 CN2022125071W WO2023098311A1 WO 2023098311 A1 WO2023098311 A1 WO 2023098311A1 CN 2022125071 W CN2022125071 W CN 2022125071W WO 2023098311 A1 WO2023098311 A1 WO 2023098311A1
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Prior art keywords
active layer
region
electrode active
negative electrode
electrochemical device
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English (en)
French (fr)
Inventor
李菁华
王修好
石维道
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to EP22900116.9A priority Critical patent/EP4394915A4/en
Publication of WO2023098311A1 publication Critical patent/WO2023098311A1/zh
Priority to US18/620,380 priority patent/US20240243252A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • H01M50/474—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof characterised by their position inside the cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/471—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof
    • H01M50/48—Spacing elements inside cells other than separators, membranes or diaphragms; Manufacturing processes thereof characterised by the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • H01M50/597—Protection against reversal of polarity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the field of electrochemical technology, in particular to an electrochemical device and an electronic device.
  • Lithium-ion batteries have the advantages of high energy storage density, high open circuit voltage, low self-discharge rate, long cycle life, and good safety. They are widely used in various fields such as portable electric energy storage, electronic equipment, and electric vehicles. But it also puts forward higher requirements on the comprehensive performance of lithium-ion batteries, such as having a high charging rate and good cycle performance at the same time.
  • Super fast charging lithium-ion batteries are widely used in portable electronic devices due to their high charging rate.
  • the positive active layer on the positive electrode sheet of the super fast charging lithium-ion battery is usually zebra coated, and multiple active layers parallel to each other are formed along the width direction of the electrode sheet.
  • the inventors of the present application found that during the coating process, due to the surface tension of the slurry, the thickness of the edge area of the active layer is smaller than the thickness of the middle area of the active layer.
  • the prepared With the winding or stacking of the pole pieces, the prepared The thickness difference between the edge area and the middle area of the electrode assembly along the width direction of the pole piece will become more and more significant, so that the pressure on the end and the middle of the prepared lithium-ion battery will be unbalanced during the hot pressing process, resulting in the end and middle areas.
  • the density of the solid electrolyte interface (SEI) film formed on the negative electrode sheet in the middle is quite different, which affects the cycle performance of the lithium-ion battery.
  • the purpose of the present application is to provide an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device.
  • the first aspect of the present application provides an electrochemical device, which includes an electrode assembly, the electrode assembly includes a negative electrode sheet and a positive electrode sheet, and the negative electrode sheet includes a negative electrode current collector and an electrode located on the surface of the negative electrode current collector.
  • Negative electrode active layer the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer positioned on the surface of the positive electrode current collector, the width of the negative electrode active layer is Ha, along the width direction of the negative electrode active layer, the negative electrode active layer
  • the layer includes opposite first edges and second edges, the negative electrode active layer includes a first region and a second region, and the first region is a region from the first edge to a distance Ha/4 from the first edge, The second region is a region from Ha/4 to 3Ha/4 from the first edge; the electrochemical device is disassembled at a state of charge of 50%, and the unit area of the first region is The charge transfer impedance of the second region is Rct1, and the charge transfer impedance of the second region per unit area is Rc
  • the average thickness H1 of the negative electrode active layer in the first region and the average thickness H2 of the negative electrode active layer in the second region satisfy: (H2-H1)/H2 ⁇ 0.15.
  • the difference in the thickness of the negative electrode active layer in the first region and the second region is small, which is conducive to improving the consistency of the lithium intercalation capacity per unit area between the first region and the second region, and reducing the risk of local lithium precipitation, which is beneficial Improve cycle performance of electrochemical devices.
  • the electrochemical device satisfies at least one of the following conditions: (iv) 60m ⁇ /mm 2 ⁇ Rct1 ⁇ 100m ⁇ /mm 2 ; (v) 60m ⁇ /mm 2 ⁇ Rct2 ⁇ 80m ⁇ / mm 2 .
  • the SEI film formed on the negative electrode active layer in the first region and/or the second region is denser, which is beneficial to improve the cycle performance of the electrochemical device.
  • the width of the positive active layer is Hb, along the width direction of the positive active layer, the positive active layer includes opposite third edges and fourth edges, the positive active layer Including a third area and a fourth area, the third area is the area from the third edge to the distance Hb/4 from the third edge, and the fourth area is the distance from the third edge Hb/4 to the distance
  • the average thickness H3 of the positive electrode active layer in the third region and the average thickness H4 of the positive electrode active layer in the fourth region satisfy: (H4-H3)/H4 ⁇ 0.3.
  • the thickness difference between the end and the middle of the electrode assembly can be reduced, and the compactness of the SEI film formed on the negative electrode active layer in the first region can be improved; the other On the one hand, it can reduce the difference in the delithiation capacity of the positive electrode active layer in the third region and the fourth region, which is beneficial to improve the lithium precipitation phenomenon of the negative electrode sheet, and then improve the cycle performance of the electrochemical device.
  • 0.05 ⁇ (H4-H3)/H4 ⁇ 0.2 0.05 ⁇ (H4-H3)/H4 ⁇ 0.2.
  • H4-H3 ⁇ 25 ⁇ m In some embodiments of the present application, H4-H3 ⁇ 25 ⁇ m.
  • the width direction of the negative electrode active layer includes a first protruding region that does not overlap with the positive electrode active layer, and the positive electrode sheet
  • An insulating layer is also included, and viewed along the thickness direction of the negative electrode sheet, the insulating layer at least partially overlaps with the first protruding region.
  • the width of the negative electrode active layer is greater than the width of the positive electrode active layer, which can reduce the risk of lithium separation at the edge of the negative electrode active layer, but the negative electrode active layer at the edge has no positive electrode active layer on the opposite side, resulting in a smaller thickness at the edge of the electrode assembly.
  • the setting of the insulating layer can fill the gap, thereby improving the interface of the first extension region in the negative electrode active layer, reducing the risk of lithium deposition at the edge of the negative electrode sheet, and improving the cycle performance of the electrochemical device.
  • the insulating layer includes inorganic particles, which is conducive to obtaining an insulating layer with good hardness, which can provide sufficient support during the thermocompression forming process, and improves the stability of the first protruding region in the negative electrode active layer. interface, thereby improving the cycle performance of the electrochemical device.
  • the insulating layer further includes an adhesive.
  • the inorganic particles include HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, BaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2.
  • SiO 2 boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanate, lithium germanium thiophosphate, lithium nitride, SiS 2 At least one of glass, P 2 S 5 glass, Li 2 O, LiF, LiOH, Li 2 CO 3 , LiAlO 2 , lithium germanium phosphorus sulfur ceramics or garnet ceramics.
  • the binder includes polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, polyurethane, fluorinated rubber, polyvinyl alcohol or At least one of sodium polyacrylate.
  • the mass percentage of the binder is 5% to 40%.
  • the internal resistance R of the electrochemical device is 15m ⁇ to 19m ⁇ ;
  • the negative electrode active layer has a compacted density of 1.0 g/cm 3 to 1.9 g/cm 3 . In some embodiments of the present application, the porosity of the negative electrode active layer is 20% to 40%. In some embodiments of the present application, the positive electrode active layer has a compacted density of 3.5 g/cm 3 to 4.5 g/cm 3 . In some embodiments of the present application, the positive active layer has a porosity of 20% to 45%. When the electrochemical device satisfies at least one of the above characteristics, it is beneficial to improve the cycle performance and/or electrochemical performance of the electrochemical device.
  • a second aspect of the present application provides an electronic device, which includes the electrochemical device in any one of the foregoing embodiments.
  • the electrochemical device provided by the present application has good cycle performance, so the electronic device provided by the present application has a long service life.
  • the present application provides an electrochemical device and an electronic device, the electrochemical device includes an electrode assembly, the electrode assembly includes a negative electrode sheet and a positive electrode sheet, the negative electrode sheet includes a negative electrode collector and a negative active layer located on the surface of the negative electrode collector, and the positive electrode
  • the sheet includes a positive electrode current collector and a positive electrode active layer positioned on the surface of the positive electrode current collector.
  • the width of the negative electrode active layer is Ha. Along the width direction of the negative electrode active layer, the negative electrode active layer includes opposite first and second edges.
  • the negative electrode sheet includes The first area and the second area, the first area is the area from the first edge to Ha/4 from the first edge, and the second area is the area from Ha/4 to the first edge 3Ha/4 from the first edge; electrochemical The device is disassembled at 50% state of charge, the charge transfer impedance of the first area per unit area is Rct1, and the charge transfer impedance of the second area per unit area is Rct2, satisfying: 85% ⁇ Rct1/Rct2 ⁇ 140%.
  • Figure 1 is a schematic diagram of preparing positive pole pieces by zebra coating
  • Fig. 2 is the schematic diagram of the negative electrode active layer in one embodiment of the present application.
  • FIG. 3 is a schematic diagram of an electrode assembly in an embodiment of the present application.
  • Figure 4 is a schematic diagram of the positive active layer in an embodiment of the present application.
  • Fig. 5 is the schematic diagram of the positive pole sheet in another embodiment of the present application.
  • FIG. 6 is a schematic diagram of an adhesive tape disposed on the surface of an electrochemical device according to an embodiment of the present application.
  • the lithium-ion battery is used as an example of the electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • the positive active layer on the positive electrode sheet of the super fast charging lithium-ion battery is usually prepared by zebra coating (as shown in Figure 1), and multiple active layers parallel to each other will be formed along the width direction of the electrode sheet 10, as shown in Figure 1 In 10A, 10B, and 10C, after the preparation is completed, the positive electrode sheet containing each active layer is cut out to prepare the electrode assembly.
  • the inventors of the present application found that, during the coating process, due to the surface tension of the slurry, the thickness of the edge region of the active layer is smaller than the thickness of the middle region of the active layer. For example, in the sub-region 10A, the thickness of the region near the edge 11 is generally smaller than the thickness of the middle region of the sub-region 10A.
  • the thickness difference between the edge region and the middle region of the prepared electrode assembly along the width direction of the pole piece will become more and more significant, so that the end and middle of the lithium-ion battery will be subjected to stress during the hot pressing process.
  • the uneven pressure leads to incomplete formation of the edge region of the electrode assembly, which is not conducive to the formation of the solid electrolyte interface (SEI) film. Therefore, during the cycle of the lithium-ion battery, the edge region of the electrode assembly is more prone to lithium precipitation, which in turn affects the cycle performance of the lithium-ion battery.
  • SEI solid electrolyte interface
  • the present application provides an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device.
  • the first aspect of the present application provides an electrochemical device, which includes an electrode assembly, the electrode assembly includes a negative electrode sheet and a positive electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative active layer positioned on the surface of the negative electrode collector, and the positive electrode electrode The sheet includes a positive electrode current collector and a positive electrode active layer positioned on the surface of the positive electrode current collector.
  • the width of the negative electrode active layer is Ha. As shown in FIG.
  • the negative electrode active layer 20 along the width direction of the negative electrode active layer 20, the negative electrode active layer 20 includes opposite first edges 21 and the second edge 22, the negative electrode active layer includes a first region 20A and a second region 20B, the first region 20A is the region from the first edge 21 to Ha/4 from the first edge 21, and the second region 20B is a distance from the first edge 21
  • the charge transfer impedance of the second region is Rct2, which satisfies: 85% ⁇ Rct1/Rct2 ⁇ 140%.
  • the value of Rct1/Rct2 can be 85%, 90%, 100%, 107%, 110%, 120%, 130%, 140%, or any range therebetween.
  • the inventors of the present application have found that by controlling the ratio of the charge transfer impedance between the first region and the second region within the above range, on the one hand, it is possible to prevent the charge transfer impedance of the first region from being relatively too small, and the lithium ions will be damaged during the charging and discharging process.
  • the charge transfer impedance of the first region is relatively too large, the lithium ions on the surface of the negative active layer can be avoided. Intercalation is hindered, leading to lithium precipitation. Therefore, by adjusting the ratio of the charge transfer resistance between the first region and the second region within the above range, it is beneficial to improve the lithium precipitation phenomenon of the electrochemical device, thereby improving the cycle performance of the electrochemical device.
  • the electrode assembly 50 is a winding structure, and the electrode assembly 50 includes a negative electrode tab 51 connected to the first region of the negative electrode sheet (not shown in the figure), and a negative electrode tab 51 connected to the positive electrode sheet (not shown in the figure).
  • the positive pole tab 52 connected to the positive pole tab 52, the positive pole tab 52 and the negative pole tab 51 protrude from the edge area, along the width direction of the negative pole piece, the first area (not shown in the figure) and the edge of the electrode assembly 50 Region 50A corresponds.
  • the negative tab in this application refers to the metal conductor drawn out from the negative pole piece, which is used to lead out the current on the negative pole piece.
  • the present application has no particular limitation on the material of the negative electrode tab, and materials known in the art may be used as long as the purpose of the present application can be achieved.
  • the electrode assembly mentioned in this application may be an electrode assembly including a positive electrode sheet, a negative electrode sheet and a separator, and the above electrode assembly is taken as an example for illustration. It should be understood by those skilled in the art that the above and following descriptions are for illustration only, and do not limit the protection scope of the present application.
  • may be 5m ⁇ /mm 2 , 10m ⁇ /mm 2 , 15m ⁇ /mm 2 , 20m ⁇ /mm 2 , 25m ⁇ /mm 2 , 27m ⁇ /mm 2 or any range therebetween.
  • the charge transfer resistance difference between the first region and the second region is small, which is beneficial to improve the cycle performance of the electrochemical device.
  • the average thickness H1 of the negative electrode active layer in the first region and the average thickness H2 of the negative electrode active layer in the second region satisfy: (H2 ⁇ H1)/H2 ⁇ 0.15.
  • the value of (H2-H1)/H2 can be 0.01, 0.02, 0.05, 0.08, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15 or any range therebetween.
  • the difference in the thickness of the negative electrode active layer in the first region and the second region is small, which is conducive to improving the consistency of the lithium intercalation capacity per unit area between the first region and the second region, and reducing the risk of local lithium precipitation, which is beneficial Improve cycle performance of electrochemical devices.
  • the difference between the average thickness H1 of the negative electrode active layer in the first region and the average thickness H2 of the negative electrode active layer in the second region is H1 ⁇ H2 ⁇ 5 ⁇ m.
  • the present application has no particular limitation on the values of H1 and H2, as long as the purpose of the present application can be achieved, for example, 40 ⁇ m ⁇ H1 ⁇ 120 ⁇ m, 40 ⁇ m ⁇ H2 ⁇ 120 ⁇ m.
  • the electrochemical device satisfies at least one of the following conditions: (iv) 60m ⁇ /mm 2 ⁇ Rct1 ⁇ 100m ⁇ /mm 2 ; (v) 60m ⁇ /mm 2 ⁇ Rct2 ⁇ 80m ⁇ /mm 2 .
  • the SEI film formed on the negative electrode active layer in the first region and/or the second region is denser, which is beneficial to improve the cycle performance of the electrochemical device.
  • the value of Rct1 can be 60m ⁇ /mm 2 , 70m ⁇ /mm 2 , 80m ⁇ /mm 2 , 90m ⁇ /mm 2 , 100m ⁇ /mm 2 or any range therebetween.
  • the value of Rct2 can be 60m ⁇ /mm 2 , 65m ⁇ /mm 2 , 70m ⁇ /mm 2 , 75m ⁇ /mm 2 , 80m ⁇ /mm 2 or any range therebetween.
  • the width of the positive electrode active layer is Hb.
  • the active layer includes a third region 30A and a fourth region 30B, the third region 30A is the region from the third edge 31 to Hb/4 from the third edge 31, and the fourth region 30B is the region from the third edge 31 to Hb/4 to In the region 3Hb/4 away from the third edge 31 , the average thickness H3 of the positive electrode active layer in the third region and the average thickness H4 of the positive electrode active layer in the fourth region satisfy: (H4 ⁇ H3)/H4 ⁇ 0.3.
  • the value of (H4-H3)/H4 can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 or any range therebetween.
  • the third area is opposite to the first area.
  • the thickness difference between the end and the middle of the electrode assembly can be reduced, and the compactness of the SEI film formed on the negative electrode active layer in the first region can be improved; the other On the one hand, it can reduce the difference in the delithiation capacity of the positive electrode active layer in the third region and the fourth region, which is beneficial to improve the lithium precipitation phenomenon of the negative electrode sheet, and then improve the cycle performance of the electrochemical device.
  • the difference between the average thickness H3 of the positive electrode active layer in the third region and the average thickness H4 of the positive electrode active layer in the fourth region is H4 ⁇ H3 ⁇ 25 ⁇ m.
  • the present application has no particular limitation on the values of H3 and H4, as long as the purpose of the present application can be achieved, for example, 50 ⁇ m ⁇ H3 ⁇ 100 ⁇ m, 50 ⁇ m ⁇ H4 ⁇ 100 ⁇ m.
  • the width direction of the negative electrode active layer includes a first protruding area that does not overlap with the positive electrode active layer
  • the positive electrode sheet also includes an insulating layer.
  • the insulating layer at least partially overlaps with the first extension region.
  • the width Ha of the negative electrode active layer 20 is greater than the width Hb of the positive electrode active layer 30 , thereby forming a first protruding region.
  • the positive electrode sheet 300 includes a positive electrode active layer 30 and an insulating layer 40 arranged on the surface of the positive electrode current collector (not shown in the figure).
  • the insulating layer 40 at least partially overlaps with the first extension region.
  • the width of the negative electrode active layer is greater than the width of the positive electrode active layer, which can reduce the risk of lithium separation at the edge of the negative electrode active layer, but the negative electrode active layer at the edge has no positive electrode active layer on the opposite side, resulting in a smaller thickness at the edge of the electrode assembly 50 , through the setting of the insulating layer, the gap can be filled, thereby improving the interface of the first extension region in the negative electrode active layer, reducing the risk of lithium deposition at the edge of the negative electrode sheet, and improving the cycle performance of the electrochemical device.
  • the insulating layer 40 is located on one side of the positive electrode active layer 30 . It can be understood that, along the width direction of the positive electrode active layer, the insulating layer can also be located on both sides of the positive electrode active layer.
  • the present application has no special restrictions on the average thickness of the insulating layer and the width along the width direction of the positive pole piece, as long as the purpose of the application can be achieved, for example, the average thickness of the insulating layer is 10 ⁇ m to 100 ⁇ m, and the width along the width direction of the positive pole piece 0.5mm to 10mm.
  • the insulating layer includes inorganic particles, which is conducive to obtaining an insulating layer with good hardness, which can provide sufficient support during the thermocompression forming process, and improve the interface of the first protruding region in the negative electrode active layer, Further, the cycle performance of the electrochemical device is improved.
  • the insulating layer further includes a binder.
  • the inorganic particles include HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, BaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , SiO 2 , boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanate, lithium germanium thiophosphate, lithium nitride, SiS 2 glass, At least one of P 2 S 5 glass, Li 2 O, LiF, LiOH, Li 2 CO 3 , LiAlO 2 , lithium germanium phosphorus sulfur ceramics or garnet ceramics.
  • the binder includes polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, polyurethane, fluorinated rubber, polyvinyl alcohol, or polyacrylic acid at least one of sodium.
  • the mass percentage of the binder is 5% to 40%.
  • the mass percentage of the binder may be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range therebetween.
  • the internal resistance R of the electrochemical device is 15 m ⁇ to 19 m ⁇ .
  • the negative electrode active layer has a compacted density of 1.0 g/cm 3 to 1.9 g/cm 3 .
  • the negative electrode active layer has a porosity of 20% to 40%.
  • the positive electrode active layer has a compacted density of 3.5 g/cm 3 to 4.5 g/cm 3 .
  • the positive active layer has a porosity of 20% to 45%.
  • the internal resistance R of the electrochemical device may be 15m ⁇ , 16m ⁇ , 17m ⁇ , 18m ⁇ , 19m ⁇ or any range therebetween.
  • the obtained electrochemical device has a higher output voltage.
  • the compacted density of the negative electrode active layer can be 1.0g/cm 3 , 1.1g/cm 3 , 1.2g/cm 3 , 1.3g/cm 3 , 1.4g/cm 3 , 1.5g/cm 3 , 1.6g/cm 3 , 1.6g/cm 3 cm 3 , 1.7g/cm 3 , 1.8g/cm 3 , 1.9g/cm 3 or any range therebetween.
  • the compacted density of the positive electrode active layer can be 3.5g/cm 3 , 3.6g/cm 3 , 3.7g/cm 3 , 3.8g/cm 3 , 3.9g/cm 3 , 4.0g/cm 3 , 4.1g/cm 3 , 4.1g/cm 3 cm 3 , 4.2g/cm 3 , 4.3g/cm 3 , 4.4g/cm 3 , 4.5g/cm 3 or any range therebetween.
  • the energy density of the electrochemical device can be increased.
  • the porosity of the negative electrode active layer may be 20%, 25%, 30%, 35%, 40%, or any range therebetween.
  • the porosity of the positive active layer may be 20%, 25%, 30%, 35%, 40%, 45%, or any range therebetween.
  • the positive electrode active layer may be disposed on one surface in the thickness direction of the positive electrode current collector, or may be disposed on two surfaces in the thickness direction of the positive electrode current collector.
  • the "surface" here may refer to the entire area of the positive electrode collector or a partial area of the positive electrode collector.
  • the positive electrode current collector is not particularly limited, as long as the purpose of the present application can be achieved, for example, it may include but not limited to aluminum foil, aluminum alloy foil, or a composite current collector.
  • the thickness of the positive electrode collector there is no particular limitation on the thickness of the positive electrode collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8 ⁇ m to 12 ⁇ m.
  • the positive electrode active layer includes the positive electrode active material.
  • the present application has no special limitation on the positive electrode active material, as long as the purpose of the application can be achieved, for example, it can include lithium transition metal composite oxide or lithium transition metal phosphate compound. at least one.
  • the present application has no particular limitation on the above transition metal elements, as long as the purpose of the present application can be achieved, for example, at least one of nickel, manganese, cobalt or iron may be included.
  • the positive electrode active material may include at least one of lithium nickel cobalt manganese oxide (811, 622, 523, 111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium cobalt oxide, lithium manganate or lithium manganese iron phosphate .
  • the positive electrode active layer can also include a positive electrode binder.
  • the application has no special restrictions on the positive electrode binder, as long as the purpose of the application can be achieved, for example, it can include but not limited to fluorine-containing resin, polypropylene resin, fiber type binder , at least one of rubber-type adhesive or polyimide-type adhesive.
  • the positive electrode active layer may also include a positive electrode conductive agent, and the present application has no special limitation on the positive electrode conductive agent, as long as the purpose of the application can be achieved, for example, it may include but not limited to conductive carbon black (Super P), carbon At least one of nanotubes (CNTs), carbon fibers, acetylene black, flake graphite, Ketjen black, graphene, metal materials or conductive polymers.
  • the positive electrode conductive agent includes conductive carbon black and carbon nanotubes.
  • the aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the aforementioned carbon fibers may include, but are not limited to, vapor grown carbon fibers (VGCF) and/or carbon nanofibers.
  • the above metal material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the aforementioned conductive polymer may include but not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the positive electrode sheet may further include a conductive layer, and the conductive layer is located between the positive electrode current collector and the positive electrode active layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, for example, may include but not limited to the above-mentioned positive electrode conductive agent and the above-mentioned positive electrode binder.
  • the negative electrode active layer may be disposed on one surface in the thickness direction of the negative electrode current collector, or may be disposed on two surfaces in the thickness direction of the negative electrode current collector.
  • the "surface" here may be the entire area of the negative electrode collector, or a partial area of the negative electrode collector.
  • the negative electrode current collector is not particularly limited, as long as the purpose of this application can be achieved, for example, it may include but not limited to copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or composite Collectors, etc.
  • the thickness of the current collector of the negative electrode there is no particular limitation on the thickness of the current collector of the negative electrode, as long as the purpose of the present application can be achieved, for example, the thickness is 4 ⁇ m to 12 ⁇ m.
  • the negative electrode active layer includes a negative electrode active material, wherein the negative electrode active material is not particularly limited, as long as the purpose of the application can be achieved, for example, the negative electrode active material includes a carbon material that can reversibly intercalate/deintercalate lithium ions.
  • the carbon material may be a carbon material known in the art as a negative electrode active material, for example, the carbon material may include but not limited to crystalline carbon and/or amorphous carbon.
  • the above-mentioned crystalline carbon may include, but is not limited to, amorphous, plate-shaped, platelet-shaped, spherical or fibrous natural graphite or artificial graphite.
  • the aforementioned amorphous carbon may include, but is not limited to, at least one of soft carbon, hard carbon, mesophase pitch carbide, or calcined coke.
  • the negative electrode active material may include but not limited to natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon oxide (SiO x , x ⁇ 2) or silicon-carbon composite at least one of the Wherein, the mass ratio of silicon and carbon in the silicon-carbon composite is 1:10 to 10:1, and the Dv50 is 0.1 ⁇ m to 100 ⁇ m.
  • the negative electrode active layer may also include a negative electrode conductive agent, and the present application has no special restrictions on the negative electrode conductive agent, as long as the purpose of the application can be achieved, for example, it may include but not limited to carbon-based materials, metal-based materials or at least one of conductive polymers.
  • the above-mentioned carbon-based material is selected from at least one of conductive carbon black, acetylene black, Ketjen black or carbon fiber.
  • the above-mentioned metal-based material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the conductive polymer may include, but is not limited to, at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene, or polypyrrole.
  • the negative electrode active layer may also include a negative electrode binder.
  • the present application has no special restrictions on the negative electrode binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to polyvinyl alcohol, carboxymethyl Cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, At least one of polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin or nylon.
  • the negative electrode sheet may further include a conductive layer, and the conductive layer is located between the negative electrode current collector and the negative electrode active layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, and the conductive layer may include but not limited to the above-mentioned negative electrode conductive agent and the above-mentioned negative electrode binder.
  • the electrochemical device can also include a separator, and the present application has no special limitation on the separator, as long as the purpose of the application can be achieved, for example, it can include but not limited to polyethylene (PE), polypropylene (PP), Polytetrafluoroethylene-based polyolefin (PO)-based separator, polyester film (such as polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide At least one of film (PA), spandex, aramid film, woven film, non-woven film (non-woven fabric), microporous film, composite film, separator paper, laminated film or spun film, preferably polyethylene or polypropylene, which have a good effect on preventing short circuits and can improve the stability of electrochemical devices through the shutdown effect.
  • PET polyethylene terephthalate
  • PI polyimide film
  • PA polyamide
  • spandex aramid film
  • woven film non-woven film (non-woven fabric)
  • the separator of the present application may have a porous structure, and the pore size is not particularly limited as long as the purpose of the present application can be achieved, for example, the pore size may be 0.01 ⁇ m to 1 ⁇ m.
  • the thickness of the isolation film is not particularly limited, as long as the purpose of the present application can be achieved, for example, the thickness may be 5 ⁇ m to 500 ⁇ m.
  • a separator may include a substrate layer and a surface treatment layer.
  • the substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer can include but not limited to polyethylene, polypropylene, polyethylene terephthalate or polyimide at least one.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material.
  • Inorganic layer may include but not limited to inorganic particles of inorganic layer and binder of inorganic layer, the present application has no special limitation on inorganic particles of inorganic layer, for example, may include but not limited to aluminum oxide, silicon oxide, magnesium oxide, oxide Titanium, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate at least one of .
  • the present application has no particular limitation on the inorganic layer binder, for example, may include but not limited to polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, At least one of polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • polyvinylidene fluoride copolymer of vinylidene fluoride-hexafluoropropylene
  • polyamide polyacrylonitrile
  • polyacrylate polyacrylic acid
  • the polymer layer contains a polymer, and the polymer material may include but not limited to polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl ether, polyvinylidene fluoride At least one of ethylene or poly(vinylidene fluoride-hexafluoropropylene).
  • the electrochemical device may further include an electrolyte, which may include, but not limited to, one or more of a gel electrolyte, a solid electrolyte, and an electrolytic solution.
  • the electrolytic solution may include a lithium salt and a non-aqueous solvent.
  • lithium salts can be selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiSiF 6 , LiBOB or lithium difluoroborate.
  • the lithium salt comprises LiPF 6 .
  • the present application has no special limitation on the non-aqueous solvent, as long as the purpose of the present application can be achieved, for example, it may include but not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • the above-mentioned carbonate compound may include but not limited to at least one of chain carbonate compound, cyclic carbonate compound or fluorocarbonate compound.
  • Above-mentioned chain carbonate compound can include but not limited to dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC) or at least one of methyl ethyl carbonate (MEC).
  • the above-mentioned cyclic carbonate may include but not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinylethylene carbonate (VEC).
  • Fluorocarbonate compounds may include, but are not limited to, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2- At least one of difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • carboxylate compounds may include but are not limited to methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyl At least one of lactone, decanolactone, valerolactone, mevalonolactone or caprolactone.
  • the aforementioned ether compounds may include, but are not limited to, dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxy At least one of methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but not limited to dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2- At least one of pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.
  • the electrochemical device of the present application is not particularly limited, and it may include any device that undergoes an electrochemical reaction.
  • the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery, among others.
  • the preparation process of electrochemical devices is well known to those skilled in the art, and the present application is not particularly limited.
  • it may include but not limited to the following steps: stack the positive electrode, separator and negative electrode in sequence, and wind it as needed , folding and other operations to obtain the electrode assembly with a winding structure, put the electrode assembly into the packaging bag, inject the electrolyte into the packaging bag and seal it, and obtain an electrochemical device; or stack the positive electrode, separator and negative electrode in order, and then use Tape is used to fix the four corners of the entire laminated structure to obtain the electrode assembly of the laminated structure, the electrode assembly is placed in a packaging bag, the electrolyte is injected into the packaging bag and sealed to obtain an electrochemical device.
  • overcurrent prevention elements, guide plates, etc. can also be placed in the packaging bag as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • a sticker is placed on the surface of the packaging bag corresponding to the first area, and then heat-pressing is performed.
  • the electrochemical device prepared above is left to stand, it is put into a hot-press formation device for heat-press formation treatment, and stickers and/or protrusions are placed in the heat-press device corresponding to the position of the first region.
  • the thickness of the sticker is 5 ⁇ m to 50 ⁇ m
  • the height of the protrusion is 5 ⁇ m to 50 ⁇ m
  • the sticker can be an adhesive paper or a silicone pad.
  • the setting of stickers and/or protrusions can make the pressure between the first area and the second area of the negative electrode sheet of the electrochemical device more balanced during the hot pressing formation process, so as to achieve sufficient formation of different areas, which is conducive to improving the electrochemical device. Cycling performance of chemical devices.
  • the electrochemical device 60 includes a positive electrode tab 52 and a negative electrode tab 51
  • the sticker 70 is arranged at an area 60A on the surface of the packaging bag corresponding to the position of the first area (not shown in the figure).
  • the present application has no special limitation on the adhesive paper and the silicone pad, and the adhesive paper and the silicone pad known in the art can be used.
  • the present application has no special restrictions on the temperature, pressure and time of the thermocompression, as long as the purpose of the present application can be achieved.
  • the temperature range is generally 60°C to 100°C
  • the pressure range is 600kg to 1000kg
  • the time range is 40min to 1000kg. 60min.
  • the sticker can be removed after the heat-pressing process, and then the electrochemical device can be obtained through degassing, trimming and other processes; the thickness of the sticker can be selected according to the actual situation, as long as the purpose of this application can be achieved .
  • a second aspect of the present application provides an electronic device, which includes the electrochemical device in any one of the foregoing embodiments.
  • the electrochemical device provided by the present application has good cycle performance, so the electronic device provided by the present application has a long service life.
  • the electronic device of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • electrolyte wherein, in a dry argon atmosphere glove box, ethylene carbonate, propylene carbonate, diethyl carbonate According to the mass ratio of 3:3:4 mixed to obtain an organic solvent, then add lithium salt LiPF 6 to the organic solvent to dissolve and mix uniformly to
  • the mass concentration of LiPF 6 is 12.5%
  • the charge transfer impedance was obtained through the test of alternating current impedance spectroscopy (EIS).
  • EIS alternating current impedance spectroscopy
  • the charge transfer impedance Rct1 of the first area per unit area is obtained by cutting two rectangular samples with a size of 30 mm ⁇ 15 mm in the first area of the negative electrode sheet for testing, and normalizing according to the sample area; the second area per unit area
  • the charge transfer impedance Rct2 is obtained by cutting two rectangular samples with a size of 30mm ⁇ 15mm in the second area of the negative electrode sheet for testing, and performing normalization processing according to the sample area.
  • the lithium-ion battery was charged and discharged for the first time at 25°C, charged with a constant current of 12A to 4.05V, charged with a constant voltage of 4.05V to 9A, charged with a constant current of 9A to 4.15V, charged with a constant voltage of 4.15V to 7A, and 7A constant current charging to 4.35V, 4.35V constant voltage charging to 6A, 6A constant current charging to 4.45V, 4.45V constant voltage charging to 5A, 5A constant current charging to 4.48V, 4.48V constant voltage charging to 1A, stand still for 5min, discharge to 3.0V with a constant current of 3A, and record the discharge capacity value of the first cycle. Then, repeat 700 cycles of charging and discharging, and record the discharge capacity value of the 700th cycle, and use the following formula to calculate the cycle capacity retention rate:
  • the area percentage of lithium deposition the area of lithium deposition in the first region/the area of the first region ⁇ 100%.
  • Thickness expansion rate after 700 cycles at 25°C [(H2-H1)/H1] ⁇ 100%.
  • the positive electrode slurry was evenly coated on one surface of the positive electrode current collector aluminum foil, and then dried at 85°C to obtain a positive electrode sheet coated with a positive active layer on one side. Repeat the above steps on the other surface of the aluminum foil to obtain a positive electrode sheet coated with a positive active layer on both sides.
  • Negative electrode active material artificial graphite, negative electrode binder styrene-butadiene rubber, thickener sodium carboxymethyl cellulose are mixed according to a mass ratio of 96:2:2, deionized water is added, and mixed evenly under the action of a vacuum mixer to obtain Negative electrode slurry, wherein the solid content of the negative electrode slurry is 75%.
  • the negative electrode slurry was uniformly coated on one surface of the negative electrode current collector copper foil, and then dried at 120° C. to obtain a negative electrode sheet coated with a negative active layer on one side. Repeat the above steps on the other surface of the copper foil to obtain a negative electrode sheet coated with a negative active layer on both sides.
  • Aluminum oxide and polyvinylidene fluoride were mixed according to a mass ratio of 90:10 and added to deionized water to form an inorganic layer slurry with a solid content of 50%. Subsequently, the inorganic layer slurry was uniformly coated on one surface of a porous substrate (polyethylene, thickness 5 ⁇ m, porosity 39%), and dried to obtain a separator containing an inorganic layer.
  • a porous substrate polyethylene, thickness 5 ⁇ m, porosity 39%)
  • the electrode assembly is obtained by winding.
  • inject the electrolyte after drying, after vacuum packaging and standing still, paste the adhesive tape on the outside of the packaging bag opposite to the first area, and then heat-press and form, and the heat-press form is completed After degassing, trimming and other processes to obtain lithium-ion batteries.
  • the thickness of the gummed paper is 50 ⁇ m; the hot-pressing forming process is charged to 3.3V at a constant current of 0.02C, then charged at a constant current of 0.1C to 3.6V, and finally charged at a constant current of 0.2C to 4.45V; the forming temperature of hot-pressing is 85°C, pressure 600kg, time 42.3min.
  • Example 1-5 to Example 1-7 except that in ⁇ Preparation of Lithium-ion Batteries> the thickness of the adhesive tape is adjusted to 40 ⁇ m, 30 ⁇ m, and 10 ⁇ m, the rest are the same as Example 1-3.
  • Example 2-1 except that the positive electrode sheet is prepared according to the following steps, all the other are the same as Example 1-3:
  • Insulation layer slurry mix the binder polyvinylidene fluoride, sodium carboxymethyl cellulose and Al 2 O 3 according to the mass ratio of 1:1:8, and add N-methylpyrrolidone to mix evenly to obtain the insulation layer slurry .
  • the insulating layer slurry is coated on the surface of the positive electrode current collector on one side in the width direction of the positive electrode active layer, and the coating area of the insulating layer slurry is shown in Figure 5. Then dry to obtain a positive electrode sheet coated with an insulating layer, wherein, along the width direction of the positive electrode sheet, the width of the insulating layer is 2.6 mm, and the average thickness of the insulating layer is 25 ⁇ m.
  • Example 2-2 and Example 2-3 except that the average thickness of the insulating layer is adjusted according to Table 2, the rest are the same as Example 2-1.
  • Comparative Example 3 except for adjusting the thickness of the gummed paper to 100 ⁇ m in ⁇ Preparation of Lithium Ion Battery>, the rest is the same as that of Examples 1-4.
  • Comparative Example 1 to Comparative Example 3 From Example 1-1 to Example 1-7, Comparative Example 1 to Comparative Example 3, it can be seen that when the value of Rct1/Rct2 is within the scope of the present application, the phenomenon of lithium precipitation in the first region of the negative electrode sheet is obvious Improvement, the cycle performance of the obtained lithium ion battery is better.
  • Examples 1-1 to 1-6 with 110% ⁇ Rct1/Rct2 ⁇ 140% are more effective in improving lithium precipitation and cycle performance than Examples 1-7 with Rct1/Rct2 ⁇ 100% , the possible reason is that the diffusion of the electrolyte is relatively easy at the end of the electrode assembly, therefore, during the charging and discharging process, the risk of lithium ions being enriched at the end of the electrode assembly and causing side reactions is greater, Rct1/Rct2 When ⁇ 110%, the charge transfer resistance Rct1 of the first region of the negative electrode sheet at the end of the electrode assembly is relatively large, which can inhibit the enrichment of lithium ions at the end of the electrode assembly during charge and discharge, thereby reducing the chance of side reactions occurring at the end of the electrode assembly risk, thereby improving lithium analysis and improving the cycle performance of lithium-ion batteries.
  • Example 1-3 Example 2-1 to Example 2-3 that the setting of the insulating layer can further improve the cycle performance of the lithium ion battery.
  • the possible reason is that the width of the negative electrode active layer is greater than the width of the positive electrode active layer, which can reduce the risk of lithium separation at the edge of the negative electrode active layer, but the negative electrode active layer at the edge has no positive electrode active layer on the opposite side.
  • the thickness is small, and the gap at this place can be filled through the arrangement of the insulating layer, thereby improving the interface of the first extension region in the negative electrode active layer, thereby improving the cycle performance of the lithium ion battery.

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Abstract

本申请提供了一种电化学装置和电子装置，电化学装置包括电极组件，电极组件包括负极极片，负极极片包括负极集流体和位于负极集流体表面的负极活性层，负极活性层的宽度为Ha，沿负极活性层的宽度方向，负极活性层包括相对的第一边缘和第二边缘，负极极片包括第一区域和第二区域，第一区域为第一边缘至距离第一边缘Ha/4的区域，第二区域为距离第一边缘Ha/4至距离第一边缘3Ha/4的区域；电化学装置在50％荷电状态下拆解，单位面积第一区域的电荷转移阻抗为Rct1，单位面积第二区域的电荷转移阻抗为Rct2，满足：85％≤Rct1/Rct2≤140％。通过调控第一区域和第二区域之间电荷转移阻抗的比值在上述范围内，有利于改善电化学装置的析锂现象，从而提高电化学装置的循环性能。

Description

一种电化学装置和电子装置
本申请要求于2021年11月30日提交中国专利局、申请号为202111442112.9、发明名称为“一种电化学装置和电子装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电化学技术领域，特别是涉及一种电化学装置和电子装置。
背景技术
锂离子电池具有储能密度大、开路电压高、自放电率低、循环寿命长、安全性好等优点，广泛应用于便携式电能储存、电子设备、电动汽车等各个领域。但也对锂离子电池的综合性能提出更高的要求，例如同时具有较高的充电速率和良好的循环性能等。
发明内容
超级快充锂离子电池由于具有较高的充电速率而被广泛应用于便携式的电子设备中。超级快充锂离子电池的正极极片上的正极活性层通常采用斑马涂布的方式，沿极片宽度方向会形成多个相互平行的活性层。本申请的发明人研究发现，在涂布过程中，由于浆料表面张力的原因，会导致活性层边缘区域的厚度小于活性层中间区域的厚度，随着极片的卷绕或堆叠，制备得到的电极组件沿极片宽度方向的边缘区域和中间区域存在的厚度差会越发显著，使得制备得到的锂离子电池在热压化成过程中端部和中部受到的压力不均衡，导致在端部和中部的负极极片上形成的固体电解质界面(SEI)膜致密性差异较大，从而影响锂离子电池的循环性能。
鉴于上述问题，本申请的目的在于提供一种电化学装置和电子装置，以改善电化学装置的循环性能。
本申请的第一方面提供了一种电化学装置，其包括电极组件，所述电极组件包括负极极片和正极极片，所述负极极片包括负极集流体和位于所述负极集流体表面的负极活性层，所述正极极片包括正极集流体和位于所述正极集流体表面的正极活性层，所述负极活性层的宽度为Ha，沿所述负极活性层的宽度方向，所述负极活性层包括相对的第一边缘和第二边缘，所述负极活性层包括第一区域和第二区域，所述第一区域为所述第一边缘至距离所述第一边缘Ha/4的区域，所述第二区域为距离所述第一边缘Ha/4至距离所述第一边缘3Ha/4的区域；所述电化学装置在50％荷电状态下拆解，单位面积所述第一区域的电荷转 移阻抗为Rct1，单位面积所述第二区域的电荷转移阻抗为Rct2，满足：85％≤Rct1/Rct2≤140％。通过调控第一区域和第二区域之间电荷转移阻抗的比值在上述范围内，一方面，能够避免第一区域的电荷转移阻抗相对过小时，锂离子在其负极活性层表面富集并引发大量的副反应，导致后续阻抗快速恶化；另一方面，能够避免第一区域的电荷转移阻抗相对过大时，锂离子在其负极活性层表面的嵌入受阻，从而导致锂析出。因此，通过调控第一区域和第二区域之间电荷转移阻抗的比值在上述范围内，有利于改善电化学装置的析锂现象，从而提高电化学装置的循环性能。
在本申请的一些实施方案中，110％≤Rct1/Rct2≤140％；由于在电极组件的端部，电解液的扩散较为容易，因此，在充放电过程中，锂离子在电极组件端部富集并引发副反应的风险较大，Rct1/Rct2在上述范围内时，电极组件端部负极极片第一区域的电荷转移阻抗Rct1较大，通过提高第一区域的电荷转移阻抗Rct1，能够抑制充放电过程中锂离子在电极组件端部的富集，从而降低电极组件端部发生副反应的风险，进而提高电化学装置的循环性能。
在本申请的一些实施方案中，|Rct1-Rct2|≤27mΩ/mm 2；此时，第一区域和第二区域的电荷转移阻抗差异较小，有利于改善电化学装置的循环性能。
在本申请的一些实施方案中，所述第一区域中负极活性层的平均厚度H1和所述第二区域中负极活性层的平均厚度H2满足：(H2-H1)/H2≤0.15。此时，第一区域和第二区域中负极活性层的厚度差异较小，有利于提高单位面积第一区域和第二区域可嵌锂容量的一致性，降低局部析锂的风险，从而有利于改善电化学装置的循环性能。
在本申请的一些实施方案中，40μm≤H1≤120μm。
在本申请的一些实施方案中，40μm≤H2≤120μm。
在本申请的一些实施方案中，H2-H1≤5μm。
在本申请的一些实施方案中，所述电化学装置满足以下条件中的至少一者：(iv)60mΩ/mm 2≤Rct1≤100mΩ/mm 2；(v)60mΩ/mm 2≤Rct2≤80mΩ/mm 2。此时，第一区域和/或第二区域中负极活性层上所形成的SEI膜较为致密，有利于改善电化学装置的循环性能。
在本申请的一些实施方案中，所述正极活性层的宽度为Hb，沿所述正极活性层的宽度方向，所述正极活性层包括相对的第三边缘和第四边缘，所述正极活性层包括第三区域和第四区域，所述第三区域为所述第三边缘至距离所述第三边缘Hb/4的区域，所述第四区域为距离所述第三边缘Hb/4至距离所述第三边缘3Hb/4的区域，所述第三区域中正极活 性层的平均厚度H3和所述第四区域中正极活性层的平均厚度H4满足：(H4-H3)/H4≤0.3。通过调控(H4-H3)/H4的值在上述范围内，一方面，能够降低电极组件端部和中部的厚度差异，提高第一区域中负极活性层上所形成SEI膜的致密性；另一方面，能够降低第三区域和第四区域中正极活性层可脱锂容量的差异性，有利于改善负极极片的析锂现象，进而改善电化学装置的循环性能。
在本申请的一些实施方案中，0.05≤(H4-H3)/H4≤0.2。通过调控(H4-H3)/H4≥0.05，能够降低第三区域中正极活性层的可脱锂容量，从而可降低负极极片边缘析锂的风险，进而改善电化学装置的循环性能。
在本申请的一些实施方案中，50μm≤H3≤100μm。
在本申请的一些实施方案中，50μm≤H4≤100μm。
在本申请的一些实施方案中，H4-H3≤25μm。
在本申请的一些实施方案中，沿所述负极极片的厚度方向观察，所述负极活性层的宽度方向上包括未与所述正极活性层重叠的第一伸出区，所述正极极片还包括绝缘层，沿所述负极极片的厚度方向观察，所述绝缘层与所述第一伸出区至少部分重叠。负极活性层的宽度大于正极活性层的宽度，可以降低负极活性层边缘析锂的风险，但在边缘处的负极活性层由于对侧没有正极活性层，导致电极组件边缘处的厚度较小，通过绝缘层的设置能够填充该处间隙，从而改善负极活性层中第一伸出区的界面，降低负极极片边缘析锂的风险，进而改善电化学装置的循环性能。
在本申请的一些实施方案中，所述绝缘层包括无机颗粒，有利于得到具有良好硬度的绝缘层，在热压化成过程中能够提供充分的支撑，改善负极活性层中第一伸出区的界面，进而提高电化学装置的循环性能。
在本申请的一些实施方案中，所述绝缘层还包括粘结剂。
在本申请的一些实施方案中，所述无机颗粒包括HfO 2、SrTiO 3、SnO 2、CeO 2、MgO、NiO、CaO、BaO、ZnO、ZrO 2、Y 2O 3、Al 2O 3、TiO 2、SiO 2、勃姆石、氢氧化镁、氢氧化铝、磷酸锂、锂钛磷酸盐、锂铝钛磷酸盐、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、Li 2O、LiF、LiOH、Li 2CO 3、LiAlO 2、锂锗磷硫陶瓷或石榴石陶瓷中的至少一种。
在本申请的一些实施方案中，所述粘结剂包括聚偏氟乙烯、聚四氟乙烯、羧甲基纤维素钠、丁苯橡胶、丁腈橡胶、聚胺酯、氟化橡胶、聚乙烯醇或聚丙烯酸钠中的至少一种。
在本申请的一些实施方案中，基于所述绝缘层的质量，所述粘结剂的质量百分含量为5％至40％。
在本申请的一些实施方案中，所述电化学装置的内阻R为15mΩ至19mΩ；
在本申请的一些实施方案中，所述负极活性层的压实密度为1.0g/cm 3至1.9g/cm 3。在本申请的一些实施方案中，所述负极活性层的孔隙率为20％至40％。在本申请的一些实施方案中，所述正极活性层的压实密度为3.5g/cm 3至4.5g/cm 3。在本申请的一些实施方案中，所述正极活性层的孔隙率为20％至45％。当电化学装置满足上述特征中的至少一者，均有利于改善电化学装置的循环性能和/或电化学性能。
本申请的第二方面提供了一种电子装置，其包括前述任一实施方案中的电化学装置。本申请提供的电化学装置具有良好的循环性能，从而本申请提供的电子装置具有较长的使用寿命。
本申请提供一种电化学装置和电子装置，电化学装置包括电极组件，电极组件包括负极极片和正极极片，负极极片包括负极集流体和位于负极集流体表面的负极活性层，正极极片包括正极集流体和位于正极集流体表面的正极活性层，负极活性层的宽度为Ha，沿负极活性层的宽度方向，负极活性层包括相对的第一边缘和第二边缘，负极极片包括第一区域和第二区域，第一区域为第一边缘至距离第一边缘Ha/4的区域，第二区域为距离第一边缘Ha/4至距离第一边缘3Ha/4的区域；电化学装置在50％荷电状态下拆解，单位面积第一区域的电荷转移阻抗为Rct1，单位面积第二区域的电荷转移阻抗为Rct2，满足：85％≤Rct1/Rct2≤140％。通过调控第一区域和第二区域之间电荷转移阻抗的比值在上述范围内，有利于改善电化学装置的析锂现象，从而提高电化学装置的循环性能。
附图说明
为了更清楚地说明本发明实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为采用斑马涂布制备正极极片的示意图；
图2为本申请的一种实施方案中的负极活性层的示意图；
图3为本申请的一种实施方案中的电极组件的示意图；
图4为本申请的一种实施方案中的正极活性层的示意图；
图5为本申请的另一种实施方案中的正极极片的示意图；
图6为本申请的一种实施方案中的电化学装置表面设置胶纸的示意图。
具体实施方式
为使本发明的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本发明进一步详细说明。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
需要说明的是，本申请的具体实施方案中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
超级快充锂离子电池的正极极片上的正极活性层通常采用斑马涂布的方式进行制备(如图1所示)，沿极片10宽度方向会形成多个相互平行的活性层，例如图1中的10A、10B、10C，制备完成后裁切出包含各活性层的正极极片用于制备电极组件。本申请的发明人研究发现，在涂布过程中，由于浆料表面张力的原因，会导致活性层边缘区域的厚度小于活性层中间区域的厚度。例如，在子区域10A中，靠近边缘11的区域的厚度通常小于子区域10A的中间区域的厚度。随着极片的卷绕或堆叠，制备得到的电极组件沿极片宽度方向的边缘区域和中间区域存在的厚度差会越发显著，使得锂离子电池在热压化成过程中端部和中部受到的压力不均衡，导致电极组件的边缘区域化成不完全，不利于固体电解质界面(SEI)膜的形成。从而在锂离子电池循环过程中，电极组件的边缘区域更容易产生析锂现象，进而影响锂离子电池的循环性能。
基于上述问题，本申请提供了一种电化学装置和电子装置，以改善电化学装置的循环性能。
本申请的第一方面提供了一种电化学装置，其包括电极组件，电极组件包括负极极片和正极极片，负极极片包括负极集流体和位于负极集流体表面的负极活性层，正极极片包括正极集流体和位于正极集流体表面的正极活性层，负极活性层的宽度为Ha，如图2所示，沿负极活性层20的宽度方向，负极活性层20包括相对的第一边缘21和第二边缘22，负极活性层包括第一区域20A和第二区域20B，第一区域20A为第一边缘21至距离第一边缘21的Ha/4的区域，第二区域20B为距离第一边缘21的Ha/4至距离第一边缘21的3Ha/4的区域；电化学装置在50％荷电状态(SOC)下拆解，单位面积第一区域的电荷转移阻抗为Rct1，单位面积第二区域的电荷转移阻抗为Rct2，满足：85％≤Rct1/Rct2≤140％。例 如，Rct1/Rct2的值可以为85％、90％、100％、107％、110％、120％、130％、140％或为其间的任意范围。本申请的发明人发现，通过调控第一区域和第二区域之间电荷转移阻抗的比值在上述范围内，一方面，能够避免第一区域的电荷转移阻抗相对过小时，锂离子在充放电过程中，在其负极活性层表面富集并引发大量的副反应，导致后续阻抗快速恶化；另一方面，能够避免第一区域的电荷转移阻抗相对过大时，锂离子在其负极活性层表面的嵌入受阻，从而导致锂析出。因此，通过调控第一区域和第二区域之间电荷转移阻抗的比值在上述范围内，有利于改善电化学装置的析锂现象，从而提高电化学装置的循环性能。
进一步地，110％≤Rct1/Rct2≤140％，由于在电极组件的端部，电解液的扩散较为容易，因此，在充放电过程中，锂离子在电极组件端部富集并引发副反应的风险较大，Rct1/Rct2在上述范围内时，电极组件端部负极极片第一区域的电荷转移阻抗Rct1较大，通过提高第一区域的电荷转移阻抗Rct1，能够抑制充放电过程中锂离子在电极组件端部的富集，从而降低电极组件端部发生副反应的风险，进而提高电化学装置的循环性能。
示例性地，如图3所示，电极组件50为卷绕结构，电极组件50包括与负极极片(图中未示出)第一区域连接的负极极耳51，以及与正极极片(图中未示出)连接的正极极耳52，正极极耳52和负极极耳51从边缘区域伸出，沿负极极片宽度方向，第一区域(图中未示出)与电极组件50的边缘区域50A相对应。本申请中的负极极耳是指从负极极片上引出来的金属导体，用于将负极极片上的电流引出。本申请对负极极耳的材料没有特别限制，可以采用本领域已知的材料，只要能实现本申请的目的即可。本申请中所说的电极组件可以是包含正极极片、负极极片和隔离膜的电极组件，并以上述电极组件为例进行说明。本领域技术人员应当理解，以上和以下说明仅为举例说明，并不限定本申请的保护范围。
在本申请的一些实施方案中，|Rct1-Rct2|≤27mΩ/mm 2；例如，|Rct1-Rct2|的值可以为5mΩ/mm 2、10mΩ/mm 2、15mΩ/mm 2、20mΩ/mm 2、25mΩ/mm 2、27mΩ/mm 2或为其间的任意范围。此时，第一区域和第二区域的电荷转移阻抗差异较小，有利于改善电化学装置的循环性能。
在本申请的一些实施方案中，第一区域中负极活性层的平均厚度H1和第二区域中负极活性层的平均厚度H2满足：(H2-H1)/H2≤0.15。例如，(H2-H1)/H2的值可以为0.01、0.02、0.05、0.08、0.1、0.11、0.12、0.13、0.14、0.15或为其间的任意范围。此时，第一区域和第二区域中负极活性层的厚度差异较小，有利于提高单位面积第一区域和第二区域可嵌锂容量的一致性，降低局部析锂的风险，从而有利于改善电化学装置的循环性能。
在本申请的一些实施方案中，第一区域中负极活性层的平均厚度H1和第二区域中负极活性层的平均厚度H2之差为H1-H2≤5μm。本申请对H1和H2的值没有特别限制，只要能实现本申请的目的即可，例如40μm≤H1≤120μm、40μm≤H2≤120μm。
在本申请的一些实施方案中，电化学装置满足以下条件中的至少一者：(iv)60mΩ/mm 2≤Rct1≤100mΩ/mm 2；(v)60mΩ/mm 2≤Rct2≤80mΩ/mm 2。此时，第一区域和/或第二区域中负极活性层上所形成的SEI膜较为致密，有利于改善电化学装置的循环性能。例如，Rct1的值可以为60mΩ/mm 2、70mΩ/mm 2、80mΩ/mm 2、90mΩ/mm 2、100mΩ/mm 2或为其间的任意范围。例如，Rct2的值可以为60mΩ/mm 2、65mΩ/mm 2、70mΩ/mm 2、75mΩ/mm 2、80mΩ/mm 2或为其间的任意范围。
在本申请的一些实施方案中，正极活性层的宽度为Hb，如图4所示，沿正极活性层30的宽度方向，正极活性层30包括相对的第三边缘31和第四边缘32，正极活性层包括第三区域30A和第四区域30B，第三区域30A为第三边缘31至距离第三边缘31的Hb/4的区域，第四区域30B为距离第三边缘31的Hb/4至距离第三边缘31的3Hb/4的区域，第三区域中正极活性层的平均厚度H3和第四区域中正极活性层的平均厚度H4满足：(H4-H3)/H4≤0.3。例如，(H4-H3)/H4的值可以为0.05、0.1、0.15、0.2、0.25、0.3或为其间的任意范围。可以理解的是，在电极组件中，第三区域与第一区域位置相对。通过调控(H4-H3)/H4的值在上述范围内，一方面，能够降低电极组件端部和中部的厚度差异，提高第一区域中负极活性层上所形成SEI膜的致密性；另一方面，能够降低第三区域和第四区域中正极活性层可脱锂容量的差异性，有利于改善负极极片的析锂现象，进而改善电化学装置的循环性能。在本申请中，第三区域中正极活性层的平均厚度H3和第四区域中正极活性层的平均厚度H4之差为H4-H3≤25μm。本申请对H3和H4的值没有特别限制，只要能实现本申请的目的即可，例如50μm≤H3≤100μm、50μm≤H4≤100μm。
进一步地，0.05≤(H4-H3)/H4≤0.2。通过调控(H4-H3)/H4≥0.05，能够降低第三区域中正极活性层的可脱锂容量，从而可降低负极极片边缘析锂的风险，进而改善电化学装置的循环性能。
在本申请的一些实施方案中，沿负极极片的厚度方向观察，负极活性层的宽度方向上包括未与正极活性层重叠的第一伸出区，正极极片还包括绝缘层，沿所述负极极片的厚度方向观察，绝缘层与第一伸出区至少部分重叠。如图2和图5所示，负极活性层20的宽度Ha大于正极活性层30的宽度Hb，从而形成第一伸出区。正极极片300包括设置在正 极集流体(图中未示出)表面的正极活性层30和绝缘层40，沿负极极片的厚度方向观察，绝缘层40与第一伸出区至少部分重叠。负极活性层的宽度大于正极活性层的宽度，可以降低负极活性层边缘析锂的风险，但在边缘处的负极活性层由于对侧没有正极活性层，会导致电极组件50边缘处的厚度较小，通过绝缘层的设置能够填充该处间隙，从而改善负极活性层中第一伸出区的界面，降低负极极片边缘析锂的风险，进而改善电化学装置的循环性能。沿正极活性层30的宽度方向，绝缘层40位于正极活性层30的一侧。可以理解的是，沿正极活性层的宽度方向，绝缘层也可以位于正极活性层的两侧。本申请对绝缘层的平均厚度和沿正极极片宽度方向的宽度没有特别限制，只要能实现本申请的目的即可，例如绝缘层的平均厚度为10μm至100μm，沿正极极片宽度方向的宽度为0.5mm至10mm。
在本申请的一些实施方案中，绝缘层包括无机颗粒，有利于得到具有良好硬度的绝缘层，在热压化成过程中能够提供充分的支撑，改善负极活性层中第一伸出区的界面，进而提高电化学装置的循环性能。
在本申请的一些实施方案中，绝缘层还包括粘结剂。
在本申请的一些实施方案中，无机颗粒包括HfO 2、SrTiO 3、SnO 2、CeO 2、MgO、NiO、CaO、BaO、ZnO、ZrO 2、Y 2O 3、Al 2O 3、TiO 2、SiO 2、勃姆石、氢氧化镁、氢氧化铝、磷酸锂、锂钛磷酸盐、锂铝钛磷酸盐、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、Li 2O、LiF、LiOH、Li 2CO 3、LiAlO 2、锂锗磷硫陶瓷或石榴石陶瓷中的至少一种。
在本申请的一些实施方案中，粘结剂包括聚偏氟乙烯、聚四氟乙烯、羧甲基纤维素钠、丁苯橡胶、丁腈橡胶、聚胺酯、氟化橡胶、聚乙烯醇或聚丙烯酸钠中的至少一种。
在本申请的一些实施方案中，基于绝缘层的质量，粘结剂的质量百分含量为5％至40％。例如，粘结剂的质量百分含量可以为5％、10％、15％、20％、25％、30％、35％、40％或为其间的任意范围。
在本申请的一些实施方案中，电化学装置的内阻R为15mΩ至19mΩ。在本申请的一些实施方案中，负极活性层的压实密度为1.0g/cm 3至1.9g/cm 3。在本申请的一些实施方案中，负极活性层的孔隙率为20％至40％。在本申请的一些实施方案中，正极活性层的压实密度为3.5g/cm 3至4.5g/cm 3。在本申请的一些实施方案中，正极活性层的孔隙率为20％至45％。当电化学装置满足上述特征中的至少一者，均有利于改善电化学装置的循环性能和/或电化学性能。
例如，电化学装置的内阻R可以为15mΩ、16mΩ、17mΩ、18mΩ、19mΩ或为其间的任意范围。通过调控电化学装置的内阻在上述范围内，得到的电化学装置具有较高的输出电压。
例如，负极活性层的压实密度可以为1.0g/cm 3、1.1g/cm 3、1.2g/cm 3、1.3g/cm 3、1.4g/cm 3、1.5g/cm 3、1.6g/cm 3、1.7g/cm 3、1.8g/cm 3、1.9g/cm 3或为其间的任意范围。例如，正极活性层的压实密度可以为3.5g/cm 3、3.6g/cm 3、3.7g/cm 3、3.8g/cm 3、3.9g/cm 3、4.0g/cm 3、4.1g/cm 3、4.2g/cm 3、4.3g/cm 3、4.4g/cm 3、4.5g/cm 3或为其间的任意范围。通过调控负极活性层和/或正极活性层的压实密度在上述范围内，能够提高电化学装置的能量密度。
例如，负极活性层的孔隙率可以为20％、25％、30％、35％、40％或为其间的任意范围。例如，正极活性层的孔隙率可以为20％、25％、30％、35％、40％、45％或为其间的任意范围。通过调控负极活性层和/或正极活性层的孔隙率在上述范围内，得到的电化学装置具有良好的倍率性能。
在本申请中，正极活性层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。在本申请中，正极集流体没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为8μm至12μm。
在本申请中，正极活性层中包括正极活性材料，本申请对正极活性材料没有特别限制，只要能够实现本申请目的即可，例如可以包括锂过渡金属复合氧化物或锂过渡金属磷酸化合物中的至少一种。本申请对上述过渡金属元素没有特别限制，只要能实现本申请的目的即可，例如可以包括镍、锰、钴或铁中的至少一种。具体的，正极活性材料可以包括镍钴锰酸锂(811、622、523、111)、镍钴铝酸锂、磷酸铁锂、钴酸锂、锰酸锂或磷酸锰铁锂中的至少一种。
正极活性层还可以包括正极粘结剂，本申请对正极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于含氟树脂、聚丙烯树脂、纤维型粘结剂、橡胶型粘结剂或聚酰亚胺型粘结剂中的至少一种。
在本申请中，正极活性层中还可以包括正极导电剂，本申请对正极导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米 管(CNTs)、碳纤维、乙炔黑、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种，优选地，正极导电剂包括导电炭黑和碳纳米管。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
任选地，正极极片还可以包括导电层，导电层位于正极集流体和正极活性层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，例如可以包括但不限于上述正极导电剂和上述正极粘结剂。
在本申请中，负极活性层可以设置于负极集流体厚度方向上的一个表面上，也可以设置于负极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。本申请中，负极集流体没有特别限制，只要能够实现本申请目的即可，例如，可以包括但不限于铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。在本申请中，对负极的集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为4μm至12μm。
本申请中，负极活性层包括负极活性材料，其中，负极活性材料没有特别限制，只要能实现本申请的目的即可，例如负极活性材料包括可逆地嵌入/脱嵌锂离子的碳材料。碳材料可以是本领域已知的用作负极活性材料的碳材料，例如，碳材料可以包括但不限于结晶碳和/或非晶碳。上述结晶碳可以包括但不限于无定形的、片形的、小片形的、球形的或纤维状的天然石墨或人造石墨。上述非晶碳可以包括但不限于软碳、硬碳、中间相沥青碳化物或煅烧焦中的至少一种。示例性地，负极活性材料可以包括但不限于天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、氧化硅(SiO x，x<2)或硅-碳复合物中的至少一种。其中，硅-碳复合物中硅与碳的质量比为1:10至10:1、Dv50为0.1μm至100μm。
在本申请中，负极活性层中还可以包括负极导电剂，本申请对负极导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于基于碳的材料、基于金属的材料或导电聚合物中的至少一种。上述基于碳的材料选自导电碳黑、乙炔黑、科琴黑或碳纤维中的至少一种。上述基于金属的材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。导电聚合物可以包括但不限于聚亚 苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
在本申请中，负极活性层中还可以包括负极粘结剂，本申请对负极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、聚丙烯酸、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙中的至少一种。
任选地，负极极片还可以包括导电层，导电层位于负极集流体和负极活性层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，导电层可以包括但不限于上述负极导电剂和上述负极粘结剂。
在本申请中，电化学装置还可以包括隔离膜，本申请对隔离膜没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯(PE)、聚丙烯(PP)、聚四氟乙烯为主的聚烯烃(PO)类隔离膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜中的至少一种，优选为聚乙烯或聚丙烯，它们对防止短路具有良好的作用，并可以通过关断效应改善电化学装置的稳定性。本申请的隔离膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔离膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm。
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括但不限于聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层可以包括但不限于无机物层无机颗粒和无机物层粘结剂，本申请对无机物层无机颗粒没有特别限制，例如，可以包括但不限于氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。本申请对无机物层粘结剂没有特别限制，例如，可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、 聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。聚合物层中包含聚合物，聚合物的材料可以包括但不限于聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
在本申请中，电化学装置还可以包括电解质，电解质可以包括但不限于凝胶电解质、固态电解质和电解液中的一种或多种。其中，电解液可以包括锂盐和非水溶剂。
本申请对锂盐没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于锂盐可以选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB或者二氟硼酸锂中的至少一种。优选地，锂盐包括LiPF 6。
本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。上述环状碳酸酯可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施方案中，电化学装置可以包括但不限于：锂金属二次电池、锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极、隔离膜和负极按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到电化学装置；或者，将正极、隔离膜和负极按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装袋内，将电解液注入包装袋并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止电化学装置内部的压力上升、过充放电。
在本申请中，将上述制备得到的电化学装置经过静置后，在与第一区域对应的包装袋表面设置贴纸，然后进行热压化成处理。或者，将上述制备得到的电化学装置经过静置后，放入热压化成装置中进行热压化成处理，在与第一区域位置对应的热压装置中设置贴纸和/或凸起。其中，贴纸的厚度为5μm至50μm，凸起的高度为5μm至50μm，贴纸可以为胶纸或者硅胶垫。贴纸和/或凸起的设置可以使得电化学装置在热压化成过程中负极极片第一区域和第二区域之间受到压力能够更加均衡，以实现不同区域的充分化成，从而有利于提高电化学装置的循环性能。示例性地，如图6所示，电化学装置60包括正极极耳52和负极极耳51，贴纸70设置在与第一区域(图中未示出)位置对应的包装袋表面的区域60A处。本申请对胶纸和硅胶垫没有特别限制，可以采用本领域已知的胶纸和硅胶垫。本申请对热压化成的温度、压力和时间没有特别限制，只要能实现本申请的目的即可，例如，温度范围一般为60℃至100℃、压力范围为600kg至1000kg、时间范围为40min至60min。可以理解的是，在热压化成处理结束后可以将贴纸去除，然后经过脱气、切边等工序得到电化学装置；贴纸的厚度可以根据实际情况进行选择，只要能实现本申请的目的即可。
本申请的第二方面提供了一种电子装置，其包括前述任一实施方案中的电化学装置。本申请提供的电化学装置具有良好的循环性能，从而本申请提供的电子装置具有较长的使用寿命。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电 池和锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方案进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
电荷转移阻抗测试：
将50％SOC的锂离子电池拆解得到负极极片密封存储，在手套箱中将负极极片取出，并在同一区域裁剪两片尺寸为30mm×15mm的矩形样品，使用上述两片样品以负极-隔离膜-负极的形式和包装袋组装成对称电池，滴入适量(0.2g)电解液(其中，在干燥的氩气气氛手套箱中，将碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯按照质量比为3:3:4混合得到有机溶剂，然后向有机溶剂中加入锂盐LiPF 6溶解并混合均匀，得到电解液。基于电解液的质量，LiPF 6的质量浓度为12.5％)并封装。静置6h后，通过交流阻抗图谱(EIS)测试获得电荷转移阻抗，测试温度为20±5℃，频率范围为30mHz至500KHz，扰动电压为5mV。
单位面积第一区域的电荷转移阻抗Rct1是在负极极片的第一区域裁剪两片尺寸为30mm×15mm的矩形样品进行测试，并根据样品面积进行归一化处理获得；单位面积第二区域的电荷转移阻抗Rct2是在负极极片的第二区域裁剪两片尺寸为30mm×15mm的矩形样品进行测试，并根据样品面积进行归一化处理获得。
循环容量保持率测试：
将锂离子电池在25℃下进行首次充放电，以12A恒流充电至4.05V，以4.05V恒压充电至9A，以9A恒流充电至4.15V，以4.15V恒压充电至7A，以7A恒流充电至4.35V，以4.35V恒压充电至6A，以6A恒流充电至4.45V，以4.45V恒压充电至5A，以5A恒流充电至4.48V，以4.48V恒压充电至1A，静置5min，以3A恒流放电至3.0V，记录首次循环放电容量值。然后，重复进行700次循环充放电，并记录第700次循环的放电容量值，使用下述公式计算循环容量保持率：
25℃循环700圈容量保持率＝(第700次循环的放电容量/首次循环的放电容量)×100％。
析锂面积百分比测试：
将上述循环容量保持率测试后的锂离子电池拆解，观察负极极片第一区域的析锂情况，析锂面积百分比＝第一区域析锂面积/第一区域面积×100％。
厚度膨胀率测试：
将锂离子电池在25℃下进行首次充放电，在0.5C充电倍率下恒流充电到4.45V，然后以4.45V恒压充电到0.025C，测量首次循环满充时锂离子电池的厚度计为H1，静置5min后，在0.5C倍率下恒流放电到3.0V。然后，重复进行700次循环充放电，并测量第700次循环满充时锂离子电池的厚度计为H2，使用下述公式计算厚度膨胀率：
25℃循环700圈厚度膨胀率＝[(H2-H1)/H1]×100％。
内阻R的测试：
使用电阻测试仪的正极(红色)/负极(黑色)夹子夹住锂离子电池的正负极，读下电阻测试仪表盘上的内阻数据即锂离子电池的内阻R。
实施例1-1
<正极极片的制备>
将正极活性材料LiCoO 2、导电剂乙炔黑、正极粘结剂聚偏二氟乙烯按照质量比为94:3:3进行混合，加入N-甲基吡咯烷酮，在真空搅拌机作用下混合均匀，获得正极浆料，其中正极浆料的固含量为70％。将正极浆料均匀涂覆于正极集流体铝箔的一个表面上，之后在85℃下烘干，得到单面涂覆有正极活性层的正极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂覆有正极活性层的正极极片，正极活性层的涂布重量为0.451±0.007g/1540.25mm 2。然后经过冷压、分条、裁片后，得到正极活性层宽度为74mm的正极极片。其中，H3＝65μm，H4＝90μm，(H4-H3)/H4＝0.28，正极活性层的压实密度为4.15g/cm 3，正极活性层的孔隙率为25％，冷压压力为60吨。
<负极极片的制备>
将负极活性材料人造石墨、负极粘结剂丁苯橡胶、增稠剂羧甲基纤维素钠按照质量比为96:2:2进行混合，加入去离子水，在真空搅拌机作用下混合均匀，获得负极浆料，其中负极浆料的固含量为75％。将负极浆料均匀涂覆于负极集流体铜箔的一个表面上，之后在120℃下烘干，得到单面涂覆有负极活性层的负极极片。在铜箔的另一个表面上重复以上步骤，即得到双面涂覆有负极活性层的负极极片，负极活性层的涂覆量为0.2304±0.007g/1540.25mm 2。然后经过冷压、分条、裁片后，得到负极活性层宽度为76mm的负极极片。其中，H1＝95μm，H2＝100μm，(H2-H1)/H2＝0.05，负极活性层的压实密度为1.74g/cm 3，负极活性层的孔隙率为30％，冷压压力为60吨。
<电解液的制备>
在干燥的氩气气氛手套箱中，将碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯按照质量比为 3:3:4混合得到有机溶剂，然后向有机溶剂中加入锂盐LiPF 6溶解并混合均匀，得到电解液。其中，基于电解液的质量，LiPF 6的质量浓度为12.5％。
<隔离膜的制备>
将氧化铝与聚偏二氟乙烯依照质量比90:10混合并将其加入到去离子水中以形成固含量为50％的无机物层浆料。随后将无机物层浆料均匀涂布到多孔基材(聚乙烯，厚度5μm，孔隙率为39％)的一个表面上，经过干燥处理以得到含有无机物层的隔离膜。
<锂离子电池的制备>
将上述制备得到的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间以起到隔离的作用，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置后，在与第一区域位置相对的包装袋外粘贴胶纸，然后热压化成，热压化成结束后经脱气、切边等工序得到锂离子电池。其中，胶纸厚度为50μm；热压化成流程是以0.02C恒流充电到3.3V，再以0.1C恒流充电到3.6V，最后以0.2C恒流充电到4.45V；热压化成温度为85℃、压力为600kg、时间为42.3min。
实施例1-2至实施例1-4中，除了依次调整制备正极极片的冷压压力为65吨、70吨、75吨，使得H3和H4如表1所示，并且实施例1-4中的H1＝98μm，H2＝100μm以外，其余与实施例1-1相同。
实施例1-5至实施例1-7中，除了<锂离子电池的制备>中依次调整胶纸的厚度为40μm、30μm、10μm以外，其余与实施例1-3相同。
实施例2-1中，除了按照以下步骤制备正极极片以外，其余与实施例1-3相同：
绝缘层浆料：将粘结剂聚偏氟乙烯、羧甲基纤维素钠以及Al 2O 3按照质量比为1：1：8混合，并加入N-甲基吡咯烷酮混合均匀得到绝缘层浆料。
得到双面涂覆有正极活性层的正极极片后，在正极活性层宽度方向的一侧正极集流体表面上涂覆绝缘层浆料，绝缘层浆料的涂覆区域如图5所示，然后烘干得到涂覆有绝缘层的正极极片，其中，沿正极极片宽度方向，绝缘层的宽度为2.6mm，绝缘层的平均厚度为25μm。
实施例2-2和实施例2-3中，除了按照表2调整绝缘层的平均厚度以外，其余与实施例2-1相同。
对比例1中，除了<锂离子电池的制备>在与第一区域位置相对的包装袋外未粘贴胶纸以外，其余与实施例1-1相同。
对比例2中，除了<锂离子电池的制备>在与第一区域位置相对的包装袋外未粘贴胶纸以外，其余与实施例1-3相同。
对比例3中，除了<锂离子电池的制备>中调整胶纸的厚度为100μm以外，其余与实施例1-4相同。
各实施例和各对比例的制备参数及性能测试如表1至表2所示。
表1
Figure PCTCN2022125071-appb-000001
从实施例1-1至实施例1-7、对比例1至对比例3可以看出，当Rct1/Rct2的值在本申请的范围内，负极极片中第一区域的析锂现象得到明显改善，得到的锂离子电池的循环性能更好。特别地，110％≤Rct1/Rct2≤140％的实施例1-1至实施例1-6相比于Rct1/Rct2<100％的实施例1-7，改善析锂和循环性能的效果更加优异，可能的原因在于：由于在电极组件的端部，电解液的扩散较为容易，因此，在充放电过程中，锂离子在电极组件端部富集并引发副反应的风险较大，Rct1/Rct2≥110％时，电极组件端部负极极片第一区域的电荷转移阻抗Rct1较大，能够抑制充放电过程中锂离子在电极组件端部的富集，从而降低电极组件端部发生副反应的风险，进而改善析锂、提高锂离子电池的循环性能。
表2
Figure PCTCN2022125071-appb-000002
注：表2中的“/”表示不存在对应的参数或物质。
从实施例1-3、实施例2-1至实施例2-3可以看出，绝缘层的设置可以进一步改善锂离子电池的循环性能。可能的原因在于：负极活性层的宽度大于正极活性层的宽度，可以降低负极活性层边缘析锂的风险，但在边缘处的负极活性层由于对侧没有正极活性层，导致电极组件边缘处的厚度较小，通过绝缘层的设置能够填充该处间隙，从而改善负极活性层中第一伸出区的界面，进而改善锂离子电池的循环性能。
需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体与另一个实体区分开来，而不一定要求或者暗示这些实体之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其它变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其它要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。
本说明书中的各个实施方案均采用相关的方式描述，各个实施方案之间相同相似的部分互相参见即可，每个实施方案重点说明的都是与其它实施例的不同之处。
以上所述仅为本发明的较佳实施例，并不用以限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明保护的范围之内。

Claims (10)

  1. 一种电化学装置，其包括电极组件，所述电极组件包括负极极片和正极极片，所述负极极片包括负极集流体和位于所述负极集流体表面的负极活性层，所述正极极片包括正极集流体和位于所述正极集流体表面的正极活性层，所述负极活性层的宽度为Ha，沿所述负极活性层的宽度方向，所述负极活性层包括相对的第一边缘和第二边缘，所述负极活性层包括第一区域和第二区域，所述第一区域为所述第一边缘至距离所述第一边缘Ha/4的区域，所述第二区域为距离所述第一边缘Ha/4至距离所述第一边缘3Ha/4的区域；
    所述电化学装置在50％荷电状态下拆解，单位面积所述第一区域的电荷转移阻抗为Rct1，单位面积所述第二区域的电荷转移阻抗为Rct2，满足：85％≤Rct1/Rct2≤140％。
  2. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (i)110％≤Rct1/Rct2≤140％；
    (ii)|Rct1-Rct2|≤27mΩ/mm 2；
    (iii)所述第一区域中负极活性层的平均厚度H1和所述第二区域中负极活性层的平均厚度H2满足：(H2-H1)/H2≤0.15。
  3. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (iv)60mΩ/mm 2≤Rct1≤100mΩ/mm 2；
    (v)60mΩ/mm 2≤Rct2≤80mΩ/mm 2。
  4. 根据权利要求1所述的电化学装置，其中，所述正极活性层的宽度为Hb，沿所述正极活性层的宽度方向，所述正极活性层包括相对的第三边缘和第四边缘，所述正极活性层包括第三区域和第四区域，所述第三区域为所述第三边缘至距离所述第三边缘Hb/4的区域，所述第四区域为距离所述第三边缘Hb/4至距离所述第三边缘3Hb/4的区域，所述第三区域中正极活性层的平均厚度H3和所述第四区域中正极活性层的平均厚度H4满足：(H4-H3)/H4≤0.3。
  5. 根据权利要求4所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (vi)0.05≤(H4-H3)/H4≤0.2；
    (vii)50μm≤H3≤100μm；
    (viii)50μm≤H4≤100μm；
    (ix)H4-H3≤25μm。
  6. 根据权利要求2所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (1)40μm≤H1≤120μm；
    (2)40μm≤H2≤120μm；
    (3)H2-H1≤5μm。
  7. 根据权利要求1所述的电化学装置，其中，沿所述负极极片的厚度方向观察，所述负极活性层的宽度方向上包括未与所述正极活性层重叠的第一伸出区，所述正极极片还包括绝缘层，沿所述负极极片的厚度方向观察，所述绝缘层与所述第一伸出区至少部分重叠。
  8. 根据权利要求7所述的电化学装置，其中，所述绝缘层包括粘结剂和无机颗粒，所述绝缘层满足以下条件中的至少一者：
    (a)所述无机颗粒包括HfO 2、SrTiO 3、SnO 2、CeO 2、MgO、NiO、CaO、BaO、ZnO、ZrO 2、Y 2O 3、Al 2O 3、TiO 2、SiO 2、勃姆石、氢氧化镁、氢氧化铝、磷酸锂、锂钛磷酸盐、锂铝钛磷酸盐、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、Li 2O、LiF、LiOH、Li 2CO 3、LiAlO 2、锂锗磷硫陶瓷或石榴石陶瓷中的至少一种；
    (b)所述粘结剂包括聚偏氟乙烯、聚四氟乙烯、羧甲基纤维素钠、丁苯橡胶、丁腈橡胶、聚胺酯、氟化橡胶、聚乙烯醇或聚丙烯酸钠中的至少一种；
    (c)基于所述绝缘层的质量，所述粘结剂的质量百分含量为5％至40％。
  9. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (d)所述电化学装置的内阻R为15mΩ至19mΩ；
    (e)所述负极活性层的压实密度为1.0g/cm 3至1.9g/cm 3；
    (f)所述负极活性层的孔隙率为20％至40％；
    (g)所述正极活性层的压实密度为3.5g/cm 3至4.5g/cm 3；
    (h)所述正极活性层的孔隙率为20％至45％。
  10. 一种电子装置，其包括权利要求1至9中任一项所述的电化学装置。
PCT/CN2022/125071 2021-11-30 2022-10-13 一种电化学装置和电子装置 Ceased WO2023098311A1 (zh)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117497761A (zh) * 2023-12-01 2024-02-02 宁德时代新能源科技股份有限公司 负极极片、二次电池以及用电装置
CN118244140A (zh) * 2024-05-28 2024-06-25 宁德时代新能源科技股份有限公司 固体电解质界面sei成膜质量的表征方法和装置

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114156433B (zh) * 2021-11-30 2024-06-28 宁德新能源科技有限公司 一种电化学装置和电子装置
CN114613937B (zh) * 2022-03-15 2024-07-30 东莞新能安科技有限公司 电化学装置及电子装置
KR20240015343A (ko) * 2022-07-27 2024-02-05 주식회사 엘지에너지솔루션 이종 바인더가 블렌딩된 이차전지 전극용 절연 조성물, 그 제조방법 및 상기 전연 조성물을 포함하는 이차전지 전극
CN115832606B (zh) * 2022-11-23 2024-09-06 宁德时代新能源科技股份有限公司 隔离膜、锂离子电池、电池模块、电池包及用电装置
CN116230856B (zh) * 2023-05-08 2023-07-18 宁德时代新能源科技股份有限公司 正极极片、电池以及用电设备
CN118043989A (zh) * 2023-08-31 2024-05-14 宁德新能源科技有限公司 电化学装置和应用所述电化学装置的电子装置
CN117374222A (zh) * 2023-12-07 2024-01-09 宁德时代新能源科技股份有限公司 负极极片、二次电池以及用电装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013182712A (ja) * 2012-02-29 2013-09-12 Toyota Motor Corp 非水電解質二次電池とその製造方法
CN109980177A (zh) * 2019-03-29 2019-07-05 宁德新能源科技有限公司 电极极片和包含所述电极极片的电化学装置
CN110197894A (zh) * 2018-02-26 2019-09-03 宁德新能源科技有限公司 负极极片和包括负极极片的锂离子电池
WO2021132208A1 (ja) * 2019-12-23 2021-07-01 株式会社Ｇｓユアサ 蓄電素子
CN114156433A (zh) * 2021-11-30 2022-03-08 宁德新能源科技有限公司 一种电化学装置和电子装置

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5519356B2 (ja) * 2010-03-23 2014-06-11 ナミックス株式会社 リチウムイオン二次電池及びその製造方法
CN112820852B (zh) * 2020-12-30 2022-04-15 珠海冠宇电池股份有限公司 一种负极片和锂离子电池
CN113299878B (zh) * 2021-05-21 2023-12-19 珠海冠宇电池股份有限公司 一种负极片及其应用
CN115149086A (zh) * 2021-06-15 2022-10-04 宁德新能源科技有限公司 电化学装置和电子装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013182712A (ja) * 2012-02-29 2013-09-12 Toyota Motor Corp 非水電解質二次電池とその製造方法
CN110197894A (zh) * 2018-02-26 2019-09-03 宁德新能源科技有限公司 负极极片和包括负极极片的锂离子电池
CN109980177A (zh) * 2019-03-29 2019-07-05 宁德新能源科技有限公司 电极极片和包含所述电极极片的电化学装置
WO2021132208A1 (ja) * 2019-12-23 2021-07-01 株式会社Ｇｓユアサ 蓄電素子
CN114156433A (zh) * 2021-11-30 2022-03-08 宁德新能源科技有限公司 一种电化学装置和电子装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4394915A4

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117497761A (zh) * 2023-12-01 2024-02-02 宁德时代新能源科技股份有限公司 负极极片、二次电池以及用电装置
CN117497761B (zh) * 2023-12-01 2026-03-03 宁德时代新能源科技股份有限公司 负极极片、二次电池以及用电装置
CN118244140A (zh) * 2024-05-28 2024-06-25 宁德时代新能源科技股份有限公司 固体电解质界面sei成膜质量的表征方法和装置
CN118244140B (zh) * 2024-05-28 2024-10-18 宁德时代新能源科技股份有限公司 固体电解质界面sei成膜质量的表征方法和装置

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