WO2023093298A1 - 正极极片和电池 - Google Patents

正极极片和电池 Download PDF

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Publication number
WO2023093298A1
WO2023093298A1 PCT/CN2022/122826 CN2022122826W WO2023093298A1 WO 2023093298 A1 WO2023093298 A1 WO 2023093298A1 CN 2022122826 W CN2022122826 W CN 2022122826W WO 2023093298 A1 WO2023093298 A1 WO 2023093298A1
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WIPO (PCT)
Prior art keywords
positive electrode
insulating layer
electrode sheet
positive
pole piece
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2022/122826
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English (en)
French (fr)
Inventor
常雯
付成华
叶永煌
张辰辰
朱畅
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to CN202280014512.6A priority Critical patent/CN117083748A/zh
Priority to EP22897383.0A priority patent/EP4318720A4/en
Publication of WO2023093298A1 publication Critical patent/WO2023093298A1/zh
Priority to US18/521,127 priority patent/US20240097294A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0413—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes
    • H01M10/0418—Large-sized flat cells or batteries for motive or stationary systems with plate-like electrodes with bipolar electrodes
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0436—Small-sized flat cells or batteries for portable equipment
    • H01M10/044—Small-sized flat cells or batteries for portable equipment with bipolar electrodes
    • 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
    • H01M10/0583—Construction or manufacture of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M50/50—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
    • 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
    • H01M50/593—Spacers; Insulating plates
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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 technical field of batteries, in particular to positive pole pieces and batteries.
  • lithium-ion batteries have been widely used in energy storage power systems such as water power, fire power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment , aerospace and other fields. Due to the great development of lithium-ion batteries, higher requirements have been put forward for their safety performance and so on.
  • pole pieces need to be cut. Especially when cutting the positive pole piece, it is easy to generate burrs on the cut surface of the positive pole piece, which may pierce the diaphragm, or due to the design of the positive pole piece beyond the negative pole piece (overhang), when the diaphragm shrinks, The burrs on the cutting edge of the positive electrode piece overlap with the negative electrode piece, or the positive electrode piece exceeds the negative electrode piece after the pole piece is dislocated, resulting in lithium precipitation, and the lithium dendrite overlaps with the burr or the leaked aluminum (leaked positive electrode current collector) connected, causing a short circuit and affecting the safety performance of the battery.
  • the present application is made in view of the above-mentioned technical problems, and its purpose is to provide a positive electrode sheet and a battery, which can prevent short circuits caused by burrs and improve the safety performance of the battery.
  • the present application provides a positive electrode sheet and a battery.
  • the first aspect of the present application provides a positive electrode sheet, which is arranged in a stacked battery, including: a rectangular parallelepiped body, which is formed by stacking a positive electrode active material layer and a positive electrode current collector in a first direction, and has Four side surfaces and two end surfaces, the two above-mentioned end surfaces are opposite in the above-mentioned first direction, the above-mentioned four sides are the above-mentioned first side to the above-mentioned fourth side and are respectively connected to the two above-mentioned end surfaces along the above-mentioned first direction; the positive electrode tab , which is formed by extending the positive electrode current collector from the first side to the outside of the main body; and an insulating layer, which is formed on the second side to the fourth side and covers the second side to the fourth side more than 95% of each side.
  • the positive pole piece that can be arranged in the laminated battery of the present application has four sides, and the four sides are all cut surfaces, the positive pole tab is provided on the first side, and the second to fourth sides cover the second side. 95% or more of the insulating layer on each of the side to fourth sides.
  • the insulating layer formed on the second side to the fourth side can wrap the burr formed on the second side to the fourth side, prevent short circuit caused by the burr, and improve the safety performance of the laminated battery.
  • the first side has a positive tab, the method for forming the insulating layer on the first side is relatively complicated.
  • an insulating layer with a coverage of more than 95% is formed on the second side to the fourth side respectively, and an insulating layer is not formed on the first side with the positive tab, which can improve the safety performance of the laminated battery. Improve the production efficiency of laminated batteries.
  • the insulating layer is further formed on the first side, and covers more than 95% of all areas of the first side except the area where the positive tab is formed.
  • the insulating layer with a coverage of 95% or more is formed on the second side to the fourth side, but also the first side with the positive tab, except for the area where the above-mentioned positive tab is formed, is formed. More than 95% of the insulating layer can wrap the burrs formed on the first side to the fourth side, that is, wrap all the burrs on the cut surfaces of the positive electrode sheet, and further improve the safety performance of the laminated battery.
  • the above-mentioned insulating layer extends from the side on which the above-mentioned insulating layer is formed to the end face connected to the side, and the length of the extension on the end face connected to the side is not greater than 0.5 mm.
  • the insulating layer formed on the side of the positive pole piece extends on the end face connected to the side, so it can wrap the burrs extending from the side to the end face to prevent short circuit caused by shrinkage of the diaphragm, etc., and the extension length is not more than 0.5 mm, so it can prevent the negative electrode sheet from being squeezed through the separator due to too many insulating layers, and further improve the safety performance of the laminated battery.
  • the insulating layer has a thickness of 2-30 ⁇ m on the side where the insulating layer is formed.
  • the thickness of the insulating layer on the side where the insulating layer is formed is not less than 2 ⁇ m, so it is possible to prevent the insulating layer from being too thin to completely wrap the burr when the burr is long, and the thickness of the insulating layer on the side where the insulating layer is formed
  • the thickness is not more than 30 ⁇ m, so it can prevent the insulating layer from being too thick to fall off and form particles, and improve the safety performance of the laminated battery.
  • the second aspect of the present application provides a positive electrode sheet, which is arranged in a wound battery, including: a main body that can be wound into a spiral around the axis direction, which is formed by laminating a positive electrode active material layer and a positive electrode current collector , has two main surfaces, and the two above-mentioned main surfaces are two faces facing each other in the direction in which the above-mentioned positive electrode active material layer and the above-mentioned positive electrode current collector are stacked; the positive electrode tab is composed of the above-mentioned positive electrode current collector from the top surface along the above-mentioned axis direction extending to the outside of the above-mentioned main body, the above-mentioned top surface is perpendicular to the above-mentioned axis direction and connects the two main surfaces; and an insulating layer is formed on the bottom surface and covers more than 95% of the above-mentioned bottom surface The above-mentioned top surfaces are opposite, perpendicular to the above
  • the positive electrode sheet of the present application that can be arranged in a wound battery has a top surface, a bottom surface and two main surfaces, the top surface and the bottom surface are both cut surfaces, the top surface has a positive electrode tab, and the bottom surface has a cover covering the bottom surface. More than 95% insulation.
  • the insulating layer formed on the bottom surface can wrap the burrs formed on the bottom surface, prevent short circuit caused by the burrs, and improve the safety performance of the wound battery.
  • the top surface has a positive electrode tab
  • the method of forming an insulating layer on the top surface is relatively complicated. Therefore, an insulating layer with a coverage of more than 95% is formed on the bottom surface, and no insulating layer is formed on the top surface with the positive tab, which can improve the production efficiency of the wound battery while improving the safety performance of the wound battery .
  • the insulating layer extends from the bottom surface to the main surface connected to the bottom surface, and the length extending on the main surface connected to the bottom surface is not greater than 0.5 mm.
  • the insulating layer formed on the bottom surface of the positive pole piece extends on the main surface connected to the bottom surface, so the burrs extending from the bottom surface to the main surface can be wrapped to prevent short circuit caused by shrinkage of the diaphragm, etc., and the extension length is not large. It is greater than 0.5mm, so it can prevent the insulating layer from pressing the negative electrode sheet through the separator, and further improve the safety performance of the wound battery.
  • the insulating layer has a thickness of 2-30 ⁇ m on the bottom surface.
  • the thickness of the insulating layer on the bottom surface is not less than 2 ⁇ m, so it can prevent the insulating layer from being too thin to completely cover the burr when the burr is long, and the thickness of the insulating layer on the bottom surface is not more than 30 ⁇ m, so it can prevent the insulating layer from being too thick And fall off to form particles, which improves the safety performance of the wound battery.
  • two thinned portions recessed toward the top surface are respectively provided on the region of the bottom surface connected to the two main surfaces, and the insulating layer is arranged on the thinned portions.
  • thinned portions that are recessed toward the top surface are respectively formed on the bottom surface near the two main surfaces, and the insulating layer is provided on the thinned portions, so that the insulating layer can be prevented from extending too long on the main surface and being squeezed through the diaphragm.
  • the negative pole piece is pressed, and the burrs extending from the bottom to the main surface are better wrapped to further improve the safety performance of the laminated battery.
  • the sum of the thicknesses of the insulating layer and the main body at the thinned portion is not greater than the thickness of the main body outside the thinned portion.
  • the insulating layer of the thinned portion does not protrude from the main surface of the positive electrode sheet, so the insulating layer can be prevented from pressing the negative electrode sheet through the separator, and the safety performance of the laminated battery can be further improved.
  • the thinned part is rectangular parallelepiped, the thickness along the direction perpendicular to the main surface is less than 5 ⁇ m, and the length along the axial direction is 0.5-5 mm.
  • the thinned part is made into a rectangular parallelepiped, and the thickness along the direction perpendicular to the main surface is 5 ⁇ m or less, and the length along the axial direction is 0.5 to 5 mm, so that the burrs extending from the bottom surface to the main surface can be wrapped without occupying
  • the main body has a large volume to ensure that the energy density of the battery is high enough.
  • the insulating layer is realized by one of spray coating, spot coating, and dip coating.
  • the method of forming the insulating layer will not be hindered by the structure of the laminated battery or the wound battery, and one of the methods of spraying, spot coating, and dipping can be used, which can simplify manufacturing craft.
  • the ceramic slurry for making the insulating layer includes at least a ceramic material, a binder and a solvent, and the above ceramic material accounts for 10 to 70 wt%, The binder accounts for 1-5 wt%, and the viscosity of the ceramic slurry is 100-1000 mPa ⁇ s.
  • the insulating layer is made by using ceramic slurry containing at least ceramic material, binder and solvent, so the insulation and adhesion of the insulating layer can be ensured, and the ceramic material accounts for 10-70wt%, and the binder accounts for 1-70wt%. 5 wt%, the viscosity of the ceramic slurry is 100-1000mPa ⁇ s, neither too little ceramic material and insufficient insulation, nor too much ceramic material and insufficient adhesion will cause the insulating layer to fall off.
  • the above-mentioned ceramic material is one of hydrated alumina, magnesium oxide, silicon carbide and silicon nitride, preferably hydrated alumina;
  • the binder is one or a combination of polyvinylidene fluoride, polyacrylate, methyl acrylate, ethyl acrylate, 2-methyl methacrylate and 2-ethyl methacrylate, preferably polyvinylidene fluoride Diethylene fluoride;
  • the above-mentioned solvent is N-methylpyrrolidone.
  • the third aspect of the present application provides a battery, which includes the positive electrode sheet, the negative electrode sheet and the separator of the first aspect, the positive electrode sheet and the negative electrode sheet are alternately stacked in the first direction, and the separator Sandwiched between the above-mentioned positive pole piece and the above-mentioned negative pole piece.
  • the fourth aspect of the present application provides a battery, which includes the above-mentioned positive electrode sheet, negative electrode sheet and separator of the second aspect, the above-mentioned positive electrode sheet, the above-mentioned negative electrode sheet and the above-mentioned separator are wound around the direction of the above-mentioned axis, and the above-mentioned separator Sandwiched between the above-mentioned positive pole piece and the above-mentioned negative pole piece.
  • the positive electrode sheet and the battery provided by the present application can prevent short circuit caused by burrs and improve the safety performance of the battery.
  • Fig. 1 is a front view of the laminated battery of the present application.
  • FIG. 2 is a perspective view of a positive electrode tab of a laminated battery according to an embodiment of the present application.
  • Fig. 3 is a perspective view of the positive electrode sheet of the laminated battery according to an embodiment of the present application after removing the insulating layer.
  • FIG. 4 is a perspective view of a positive electrode sheet of a laminated battery according to another embodiment of the present application.
  • Fig. 5 is a cross-sectional view of the positive pole piece of the laminated battery of the present application.
  • FIG. 6 is a schematic view of the wound battery of the present application viewed along the winding axis direction.
  • FIG. 7 is a cross-sectional view of a positive electrode tab of a wound battery according to an embodiment of the present application.
  • FIG. 8 is a cross-sectional view of a positive electrode tab of a wound battery according to another embodiment of the present application.
  • FIG. 9 is a cross-sectional view of a positive electrode tab of a wound battery according to still another embodiment of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2 ⁇ 4 and 2 ⁇ 5.
  • the numerical range “a ⁇ b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the above method includes steps (a) and (b), which means that the above method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (a) and (b) performed in sequence may also include steps (b) and (a) performed in sequence.
  • step (c) it means that step (c) may be added to the above method in any order, for example, the above method may include steps (a), (b) and (c), and may also include the step (a), (c) and (b), may also include steps (c), (a) and (b) and the like.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • the pole piece is laminated by two layers of electrode active material sandwiching a current collector, or by a layer of electrode active material layer and a current collector.
  • the current collector of the positive pole piece is composed of metal foil (usually aluminum foil).
  • the positive electrode current collector is prone to burrs. The burrs may pierce the separator sandwiched between the positive and negative pole pieces, causing the burrs to contact the positive pole piece or the negative pole piece and short circuit.
  • the positive pole piece exceeds the negative pole piece and lithium is deposited.
  • the burr is likely to overlap with the lithium dendrite, and there is a risk of short-circuit failure. Therefore, the glitch will affect the safety performance of the battery.
  • glue is applied to the edges of the wound positive electrode sheet, separator and negative electrode sheet to reduce the probability of burrs on the cutting edge, but the separator is longer than the negative electrode sheet and the negative electrode sheet is longer than the positive electrode sheet , that is, the edges of the separator, positive pole piece, and negative pole piece are not on the same plane, so it is difficult to wrap the burrs on the cutting edge of the positive pole piece by spraying, brushing, spot coating or dipping.
  • the first aspect of the present application provides a positive electrode sheet, which is arranged in a stacked battery, including: a rectangular parallelepiped body, which is formed by stacking a positive electrode active material layer and a positive electrode current collector in a first direction , having four side surfaces and two end surfaces, the two above-mentioned end surfaces are opposite in the above-mentioned first direction, the above-mentioned four side surfaces are the above-mentioned first side to the above-mentioned fourth side and are respectively connected to the two above-mentioned end surfaces along the above-mentioned first direction; the positive electrode A tab, which is formed by extending the positive electrode current collector from the first side to the outside of the main body; and an insulating layer, which is formed on the second side to the fourth side and covers the second side to the fourth side 95% or more of each of the sides.
  • the positive pole piece that can be arranged in the laminated battery of the present application has four sides, and the four sides are all cut surfaces, the positive pole tab is provided on the first side, and the second to fourth sides cover the second side. 95% or more of the insulating layer on each of the side to fourth sides.
  • the insulating layer formed on the second side to the fourth side can wrap the burr formed on the second side to the fourth side, prevent short circuit caused by the burr, and improve the safety performance of the laminated battery.
  • the first side has a positive tab, the method for forming the insulating layer on the first side is relatively complicated.
  • forming an insulating layer with a coverage degree of more than 95% on the second side to the fourth side, and not forming an insulating layer on the first side with the positive tab, can improve the safety performance of the laminated battery while improving Production efficiency of laminated cells.
  • the second aspect of the present application provides a positive electrode sheet, which is arranged in a wound battery, including: a main body that can be wound into a spiral around the axis direction, which is formed by laminating a positive electrode active material layer and a positive electrode current collector , has two main surfaces, and the two above-mentioned main surfaces are two faces facing each other in the direction in which the above-mentioned positive electrode active material layer and the above-mentioned positive electrode current collector are stacked; the positive electrode tab is composed of the above-mentioned positive electrode current collector from the top surface along the above-mentioned axis direction extending to the outside of the above-mentioned main body, the above-mentioned top surface is perpendicular to the above-mentioned axis direction and connects the two main surfaces; and an insulating layer is formed on the bottom surface and covers more than 95% of the above-mentioned bottom surface The above-mentioned top surfaces are opposite, perpendicular to the above
  • the positive electrode sheet of the present application that can be arranged in a wound battery has a top surface, a bottom surface and two main surfaces, the top surface and the bottom surface are both cut surfaces, the top surface has a positive electrode tab, and the bottom surface has a cover covering the bottom surface. More than 95% insulation.
  • the insulating layer formed on the bottom surface can wrap the burrs formed on the bottom surface, prevent short circuit caused by the burrs, and improve the safety performance of the wound battery.
  • the top surface has a positive electrode tab
  • the method of forming an insulating layer on the top surface is relatively complicated. Therefore, an insulating layer with a coverage of more than 95% is formed on the bottom surface, and no insulating layer is formed on the top surface with the positive tab, which can improve the production efficiency of the wound battery while improving the safety performance of the wound battery .
  • the third aspect of the present application provides a battery, which includes the positive electrode sheet, the negative electrode sheet and the separator of the first aspect, the positive electrode sheet and the negative electrode sheet are alternately stacked in the first direction, and the separator Sandwiched between the above-mentioned positive pole piece and the above-mentioned negative pole piece.
  • the fourth aspect of the present application provides a battery, which includes the above-mentioned positive electrode sheet, negative electrode sheet and separator of the second aspect, the above-mentioned positive electrode sheet, the above-mentioned negative electrode sheet and the above-mentioned separator are wound around the direction of the above-mentioned axis, and the above-mentioned separator Sandwiched between the above-mentioned positive pole piece and the above-mentioned negative pole piece.
  • FIG. 1 is a front view of a laminated battery 1 of the present application.
  • a laminated battery 1 includes a positive pole piece 11, a negative pole piece 12, and a separator 13.
  • the positive pole piece 11 and the negative pole piece 12 are stacked alternately in the first direction Z, and the separator 13 is sandwiched between the positive pole piece and the negative pole piece 12. Between sheet 11 and negative electrode sheet 12.
  • Fig. 2 is a perspective view of the positive pole piece 11 of the laminated battery 1 according to one embodiment of the present application
  • Fig. 3 is a perspective view of the positive pole piece 11 of the laminated battery 1 according to one embodiment of the present application after removing the insulating layer 113 .
  • the third side 11 e of the positive electrode sheet 11 faces the paper.
  • the positive pole piece 11 includes a cuboid body, a positive tab 114 and an insulating layer 113 .
  • the rectangular parallelepiped main body is formed by stacking positive electrode active material layers 112 and positive electrode current collectors 111 in the first direction Z.
  • the positive electrode active material layer 112 may be one layer or two layers.
  • the positive electrode current collector 111 is sandwiched between the two positive electrode active material layers 112 in the first direction Z.
  • the rectangular parallelepiped main body has four side surfaces 11c-11f and two end surfaces 11a, 11b.
  • the two end faces 11a, 11b face each other in the first direction Z.
  • the four sides 11c-11f are the first side 11c, the second side 11d, the third side 11e, and the fourth side 11f, and connect the two end surfaces 11a, 11b along the first direction Z respectively.
  • the positive tab 114 is formed by the positive current collector 111 extending from the first side 11c to the outside of the main body.
  • the insulating layer 113 is formed on the second side 11d to the fourth side 11f, and covers more than 95% of each of the second side 11d to the fourth side 11f. Only show the situation that insulating layer 113 completely covers (coverage degree 100%) second side 11d ⁇ fourth side 11f in Fig. 2, but not limited to this, as long as the degree of covering of insulating layer 113 is more than 95%, just can realize wrapping glitch effect.
  • the four sides 11c-11f of the positive electrode sheet 11 are all cut surfaces, and the second side 11d-the fourth side 11f respectively have an insulating layer 113 covering more than 95%.
  • the insulating layer 113 formed on the second side 11d to the fourth side 11f can wrap the burrs formed on the second side 11d to the fourth side 11f, thereby preventing a short circuit caused by the burrs and improving the safety performance of the laminated battery 1 . Since the first side 11c has the positive tab 114, the method of forming the insulating layer 113 on the first side 11c is relatively complicated.
  • an insulating layer 113 with a coverage of more than 95% is formed on the second side 11d to the fourth side 11f, and the insulating layer 113 is not formed on the first side 11c having the positive tab 114, so that the stacked battery 1 can be improved. While improving the safety performance, the production efficiency of the laminated battery 1 is improved.
  • FIG. 4 is a perspective view of a positive electrode tab 11 of a laminated battery 1 according to another embodiment of the present application.
  • the first side 11 c of the positive electrode sheet 11 faces the paper.
  • the insulating layer 113 is also formed on the first side 11c and covers more than 95% of all areas in the first side 11c except the area where the positive tab 114 is formed. 4 only shows the situation that the insulating layer 113 completely covers (100% coverage) the first side 11c except for the area where the positive electrode tab 114 is formed, but it is not limited thereto, as long as the insulating layer 113 covers Above 95%, the effect of wrapping burrs can be achieved.
  • the insulating layer 113 with a coverage of 95% or more is formed on the second side 11d to the fourth side 11f, but also the first side 11c with the positive tab 114 except the area where the positive tab 114 is formed. All regions form an insulating layer 113 covering more than 95%, so it can wrap the burrs formed on the first side 11c to the fourth side 11f, that is, wrap the burrs on all the cut surfaces of the positive electrode sheet 11, and further improve the laminated battery 1. safety performance.
  • FIG. 5 is a cross-sectional view of the positive electrode sheet 11 of the laminated battery 1 of the present application.
  • the insulating layer 113 is formed from the side surface (the second side 11d to the fourth side 11f in FIG. 2, and the first side in FIG.
  • the side surface 11c to the fourth side surface 11f) extend to the end surfaces 11a, 11b connected to the side surfaces, and the length W1 extending on the end surfaces 11a, 11b connected to the side surfaces is not more than 0.5mm.
  • the insulating layer 113 formed on the side of the positive pole piece 11 extends on the end face connected to the side, so it can wrap the burr extending from the side to the end face, prevent short circuit caused by the shrinkage of the diaphragm 13, etc., and extend the length It is not greater than 0.5mm, so it can prevent the insulating layer 113 from pressing the negative electrode sheet 12 through the separator 13, and further improve the safety performance of the laminated battery 1 .
  • the thickness D1 of the insulating layer 113 on the side where the insulating layer 113 is formed is 2 ⁇ 30 ⁇ m.
  • the thickness of the insulating layer 113 on the side where the insulating layer 113 is formed is not less than 2 ⁇ m, so it is possible to prevent the insulating layer 113 from being too thin to completely wrap the burr when the burr is long, and the insulating layer 113 is formed on the side where the insulating layer 113 is formed.
  • the thickness of the side surface of 113 is not more than 30 ⁇ m, so it can prevent the insulating layer 113 from being too thick to fall off and form particles, and improve the safety performance of the laminated battery 1 .
  • FIG. 6 is a schematic view of the wound battery 2 of the present application viewed along the winding axis direction AX.
  • the wound battery 2 includes a positive electrode tab 21 , a negative electrode tab 22 and a separator 23 .
  • the positive electrode tab, the negative electrode tab 22 and the separator 23 are wound around the axial direction AX.
  • the separator 23 is sandwiched between the positive pole piece and the negative pole piece 22 .
  • FIG. 7 is a cross-sectional view of a positive electrode tab 21 of a wound battery 2 according to an embodiment of the present application.
  • the positive pole piece 21 includes a main body, a positive pole tab 214 and an insulating layer 213.
  • the main body can be wound in a helical shape around the axis direction AX, is composed of a positive electrode active material layer 212 and a positive electrode current collector 211, and has two main surfaces 21c and 21d.
  • the main surfaces 21c and 21d are two surfaces facing each other in the direction in which the positive electrode active material layer 212 and the positive electrode current collector 211 are laminated.
  • the positive electrode active material layer 212 may be one layer or two layers. When the positive electrode active material layer 112 is two layers, as shown in FIGS.
  • the positive tab 214 is formed by the positive current collector 211 extending from the top surface 21 a along the axis direction AX to the outside of the main body.
  • the top surface 21a is perpendicular to the axial direction AX and connects the two main surfaces 21c, 21d.
  • the insulating layer 213 is formed on the bottom surface 21b and covers more than 95% of the bottom surface 21b.
  • the bottom surface 21b is opposite to the top surface 21a in the axial direction AX, is perpendicular to the axial direction AX and connects the two main surfaces 21c, 21d. 7 only shows the case where the insulating layer 213 completely covers (100% coverage) the bottom surface 21b, but it is not limited thereto. As long as the insulating layer 213 covers more than 95%, the effect of wrapping the burrs can be achieved.
  • the positive pole piece 21 in the wound battery 2 has a top surface 21a, a bottom surface 21b and two main surfaces 21c, 21d, wherein both the top surface 21a and the bottom surface 21b are cut surfaces.
  • a positive electrode tab 214 is provided on the top surface 21a, and an insulating layer 213 covering 95% or more of the bottom surface 21b is provided on the bottom surface 21b.
  • the insulating layer 213 formed on the bottom surface 21b can wrap the burrs formed on the bottom surface 21b, thereby preventing a short circuit caused by the burrs, and improving the safety performance of the wound battery.
  • the method of forming the insulating layer 213 on the top surface 21 a is relatively complicated. Therefore, an insulating layer 213 with a coverage of more than 95% is formed on the bottom surface 21b, and the insulating layer 213 is not formed on the top surface 21a having the positive electrode tab 214, which can improve the safety performance of the wound battery while improving the winding capacity. battery production efficiency.
  • FIG. 8 is a cross-sectional view of a positive electrode tab 21 of a wound battery 2 according to another embodiment of the present application.
  • the insulating layer 213 is also formed on the top surface 21 a and covers more than 95% of all areas in the top surface 21 a except the area where the positive tab 214 is formed. 8 only shows that the insulating layer 213 completely covers (100% coverage) top surface 21a except for the region where the positive pole tab 214 is formed, but it is not limited thereto, as long as the insulating layer 213 covers the More than 95%, the effect of wrapping burrs can be achieved.
  • the insulating layer 213 with a coverage of 95% or more is formed on the bottom surface 21b, but also the top surface 21a with the positive tab 214 except the area where the positive tab 214 is formed is formed with a coverage of 95%.
  • the insulating layer 213 above can therefore wrap the burrs formed on the top surface 21a and the bottom surface 21b, that is, wrap the burrs on all the cut surfaces of the positive electrode sheet 21, further improving the safety performance of the wound battery.
  • the insulating layer 213 extends from the bottom surface 21b to the main surfaces 21c, 21d connected to the bottom surface 21b, and the length W2 extended on the main surfaces 21c, 21d connected to the bottom surface 21b is not more than 0.5mm.
  • the insulating layer 213 formed on the bottom surface 21b of the positive electrode sheet 21 extends on the main surfaces 21c, 21d connected to the bottom surface 21b, so it can wrap the burrs extending from the bottom surface 21b to the main surfaces 21c, 21d, and prevent the 23 shrinkage and other conditions, and the extension length is not more than 0.5mm, so it can prevent the insulating layer 213 from pressing the negative electrode sheet 22 through the separator 23, and further improve the safety performance of the wound battery.
  • the thickness D2 of the insulating layer 213 on the bottom surface 21 b is 2 ⁇ 30 ⁇ m.
  • the thickness of the insulating layer 213 on the bottom surface 21b is not less than 2 ⁇ m, so it can prevent the insulating layer 213 from being too thin to completely wrap the burr when the burr is long, and the thickness of the insulating layer 213 on the bottom surface 21b is not greater than 30 ⁇ m, so it can be Prevent the insulating layer 213 from being too thick to fall off and form particles, and improve the safety performance of the wound battery.
  • FIG. 9 is a cross-sectional view of a positive electrode tab 21 of a wound battery 2 according to still another embodiment of the present application.
  • two thinned portions 215 recessed toward the top surface 21 a are respectively provided on the bottom surface 21 b in the area connected to the two main surfaces 21 c and 21 d, and the thinned portions 215 are provided with There is an insulating layer 213 .
  • thinned portions 215 recessed toward the top surface 21a are respectively formed in regions close to the two main surfaces 21c and 21d of the bottom surface 21b, and the insulating layer 213 is provided on the thinned portions 215, so that the insulating layer 213 can be prevented.
  • 21c, 21d extend too long to squeeze the negative electrode sheet 22 through the separator 23, and better wrap the burrs extending from the bottom surface 21b to the main surfaces 21c, 21d, further improving the safety performance of the laminated battery 1 .
  • the sum H2 of the thicknesses of the insulating layer 213 and the main body (including the positive electrode active material layer 212 and the positive electrode current collector 211 ) in the thinned portion 215 is not greater than that between the thinned portion 215
  • the insulating layer 213 of the thinned portion 215 will not protrude beyond the main surfaces 21c, 21d of the positive electrode sheet 21, so it can prevent the insulating layer 213 from pressing the negative electrode sheet 22 through the separator 23, and further improve the performance of the laminated battery. 1 safety performance.
  • the thinned portion 215 is in the shape of a cuboid, the thickness H1 along the direction perpendicular to the main surfaces 21c and 21d is less than 5 ⁇ m, and the length L1 along the axis direction AX is 0.5-5 mm.
  • the thinned portion 215 is rectangular parallelepiped, and the thickness along the direction perpendicular to the main surfaces 21c and 21d is 5 ⁇ m or less, and the length along the axial direction AX is 0.5 to 5 mm, so that it can cover from the bottom surface 21b to the main surface 21c.
  • the extended burr of 21d does not occupy a large volume of the main body at the same time, ensuring that the energy density of the battery is sufficiently high.
  • the insulating layers 113 and 213 are realized by one of spray coating, point coating and dip coating.
  • the forming method of the insulating layers 113, 213 will not be hindered by the structure of the laminated battery 1 or the wound battery 2, and the method of forming the insulating layers 113, 213 will not be hindered by the structure of the laminated battery 1 or the wound battery 2.
  • One method of coating and dip coating is sufficient, and the manufacturing process can be simplified.
  • the ceramic slurry for making the insulating layer 113, 213 includes at least ceramic material, binder and solvent, the ceramic material accounts for 10-70wt%, and the binder accounts for 1-70wt%. 5 wt%, the viscosity of the ceramic slurry is 100-1000 mPa ⁇ s.
  • the insulating layers 113, 213 are made by using ceramic slurry containing at least ceramic material, binder and solvent, so the insulating properties and adhesiveness of the insulating layers 113, 213 can be guaranteed, and the ceramic material accounts for 10-70 wt%, The binder accounts for 1 to 5 wt%, and the viscosity of the ceramic slurry is 100 to 1000 mPa ⁇ s, neither too little ceramic material and insufficient insulation, nor too much ceramic material and insufficient adhesion cause the insulating layer 113, 213 fall off.
  • the ceramic material is one of hydrated alumina, magnesia, silicon carbide and silicon nitride, preferably hydrated alumina.
  • the binder is one or a combination of polyvinylidene fluoride, polyacrylate, methyl acrylate, ethyl acrylate, 2-methyl methacrylate and 2-ethyl methacrylate, preferably polyvinylidene fluoride Diethylene fluoride.
  • the solvent is N-methylpyrrolidone.
  • the ceramic slurry the ceramic material accounts for 60wt%, the binder accounts for 5wt%, and the viscosity of the ceramic slurry is 800mPa ⁇ s.
  • the thickness of the insulating layer is 10 ⁇ m, and the length extending to the end surface of the positive pole piece is not more than 0.5 mm.
  • the negative electrode active material is coated on both sides of the negative electrode current collector, and after cold pressing and cutting, the negative electrode sheet is obtained.
  • Example 2 The laminated battery of Example 2 was obtained in the same manner as in Example 1, except that the insulating layer was not coated on the first side where the positive electrode tab was provided.
  • the stacked battery of Comparative Example 1 was obtained in the same manner as in Example 1, except that the insulating layer was not coated on the positive electrode sheet.
  • a laminated battery of Comparative Example 2 was obtained in the same manner as in Example 1 except that the thickness of the insulating layer was 1 ⁇ m.
  • Table 1 shows the evaluation results of laminated batteries. According to Table 1, when no insulating layer is provided on the cutting surface of the positive pole piece, as in Comparative Example 1, the burrs on the cutting surface are exposed, and the risk of burrs piercing the diaphragm is extremely high, with a probability of 75%. The risk of cycle charging failure caused by lithium deposition and burrs or aluminum leakage caused by exceeding the negative pole piece is also the greatest, and all 10 stacked batteries failed.
  • the insulating layer is coated on the four cutting surfaces of the positive electrode sheet, that is, the first side to the fourth side, but the thickness of the insulating layer is too low, as in Comparative Example 2, the ceramic coating cannot completely wrap the burrs, and still cannot burr the burrs.
  • Example 1 of the present application after the four cut surfaces of the positive electrode sheet of the laminated battery, that is, the first side to the fourth side, are coated with an insulating layer of a certain thickness, the burr will pierce the short circuit caused by the diaphragm. Risk and cycle charging failure risks are minimized.
  • the first side of the laminated battery has positive tabs protruding from the main body. When coating the insulating layer on the first side, the process is relatively complicated, which affects production efficiency.
  • coating the insulating layer on other cut surfaces other than the first side, that is, the second to fourth sides can also better reduce the risk of short circuit caused by burrs piercing the diaphragm and the risk of cycle charging failure The effect, while taking into account the production efficiency.
  • the main body of the positive electrode sheet with burrs on the cutting surfaces (top and bottom surfaces) is obtained, and these positive electrode sheet bodies are stacked on the top.
  • Spray the ceramic slurry on the surface and the bottom surface completely cover (100% coverage) the top surface and the bottom surface except for the positive electrode lug, and extend the length to the main surface not more than 0.5mm, and then dry to obtain the positive electrode sheet.
  • the ceramic material accounts for 60wt%
  • the binder accounts for 5wt%
  • the viscosity of the ceramic slurry is 800mPa ⁇ s.
  • the thickness of the insulating layer on the cut surface is 10 ⁇ m, and the length extending to the main surface of the positive electrode sheet is not more than 0.5 mm.
  • the negative electrode active material is coated on both sides of the negative electrode current collector, and after cold pressing and cutting, the negative electrode sheet is obtained.
  • one end of the positive electrode sheet, negative electrode sheet and two separators is fixed on the discharge roller, and the other end is laminated and fixed on the winding shaft.
  • a motor was used to rotate the winding shaft to wind the positive pole piece, the negative pole piece and the two separators to obtain the wound battery of Example 3.
  • Example 4 A wound battery of Example 4 was obtained in the same manner as in Example 3, except that an insulating layer was not applied to the top surface provided with the positive electrode tab.
  • Example 5 An insulating layer is not coated on the top surface provided with the positive electrode tab, and a thinned part provided with an insulating layer is formed on the bottom surface.
  • the length of the thinned part along the axial direction is 5 mm, and the thickness of the insulating layer at the thinned part is 5 ⁇ m. Except for this, in the same manner as in Example 3, a wound battery of Example 5 was obtained.
  • the winding battery of Comparative Example 3 was obtained in the same manner as in Example 3, except that the insulating layer was not coated on the positive electrode sheet.
  • the insulating layer is not coated on the top surface provided with the positive electrode tab, and a thinned part provided with an insulating layer is formed on the bottom surface.
  • the length of the thinned part along the axial direction is 5 mm, and the thickness of the insulating layer at the thinned part is 2 ⁇ m. Except for this, in the same manner as in Example 3, a wound battery of Comparative Example 4 was obtained.
  • Table 2 shows the evaluation results of wound batteries. According to Table 2, when no insulating layer is provided on the cutting surface of the positive pole piece, that is, the top surface and the bottom surface, as in Comparative Example 3, the probability of burrs on the cutting edge piercing the diaphragm is extremely high, and the risk of short circuit caused by burrs piercing the diaphragm The maximum, and the risk of cycle charging failure after the lithium dendrite overlaps the burr is also the greatest.
  • the probability of burrs piercing the diaphragm is extremely low, and the risk of short circuit caused by burrs piercing the diaphragm Extremely large, and the risk of cycle charging failure is extremely small.
  • the probability of burrs piercing the diaphragm is also very low, and the risk of cycle charging failure is small.
  • the thickness of the thinned portion is greater than the thickness of the insulating layer arranged on the thinned portion, although the energy density of the battery has a certain degree of loss, the diaphragm shrinks.
  • the insulating layer of the thinned part can effectively prevent the short circuit caused by the direct overlap between the positive pole piece and the negative pole piece, and effectively prevent the lithium dendrite from lapping and burring. Failure, as in Example 5.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了正极极片和电池。正极极片包括：长方体状的主体，由正极活性物质层和正极集流体在第一方向上层叠而成，具有四个侧面和在第一方向上相对两个端面，四个侧面为第一侧面～第四侧面；正极极耳，由正极集流体从第一侧面延伸到主体的外部而形成；以及绝缘层，形成并覆盖第二侧面～第四侧面的95％以上。

Description

正极极片和电池 技术领域
本申请涉及电池技术领域，尤其涉及正极极片和电池。
背景技术
近年来，随着锂离子电池技术的不断发展，锂离子电池被广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于锂离子电池取得了极大的发展，因此对其安全性能等也提出了更高的要求。
在叠片式锂离子电池和卷绕式锂离子电池这两种锂离子电池的制造过程中，都需要对极片进行裁切。尤其是在裁切正极极片时，容易在正极极片被裁切的面产生毛刺，毛刺可能会刺穿隔膜，或者由于正极极片超出负极极片(overhang)的设计，当隔膜收缩时，导致正极极片的裁切边毛刺与负极极片搭接，又或者极片错位后导致正极极片超出负极极片产生析锂，锂枝晶与毛刺或漏铝(漏出的正极集流体)搭接，从而引起短路，影响电池的安全性能。
发明内容
本申请要解决的技术问题：
本申请是鉴于上述技术问题而完成的，其目的在于，提供正极极片和电池，其能够防止由毛刺导致的短路，提高电池的安全性能。
用于解决技术问题的技术方案：
为了达到上述目的，本申请提供了正极极片和电池。
本申请的第一方面提供了一种正极极片，其设置在叠片式电池中，包括：长方体状的主体，其由正极活性物质层和正极集流体在第一方向上层叠而成，具有四个侧面和两个端面，两个上述端面在上述第一方向上相对，上述四个侧面为上述第一侧面～上述第四侧面并分别沿上述第一方向连接两个上述端面；正极极耳，其由上述正极集流体从上述第一侧面延伸到上述主体的外部而形成；以及绝缘层，其形成在上述第二侧面～上述第四侧面，并覆盖上述第二侧面～上述第四侧面中的各侧面的95％以上。
本申请的能够设置于叠片式电池中的正极极片具有四个侧面，四个侧面均为裁切面，在第一侧面具有正极极耳，在第二侧面～第四侧面具有覆盖该第二侧面～第四侧面各自的95％以上的绝缘层。由此，形成在第二侧面～第四侧面的绝缘层能够包裹形成在第二侧面～第四侧面的毛刺，防止由毛刺导致的短路，提高叠片式电池的安全性能。另外，由于第一侧面具有正极极耳，在第一侧面形成绝缘层的方法较为复杂。因此，在第二侧面～第四侧面分别形成覆盖程度在95％以上的绝缘层，并且在具有正极极耳的第一侧面不形成绝缘层，能够在提高叠片式电池的安全性能的同时，提高叠片式电池的生产效率。
在一些实施方式中，上述绝缘层还形成在上述第一侧面，并覆盖上述第一侧面中除形成上述正极极耳的区域之外的所有区域的95％以上。
由此，不仅在第二侧面～第四侧面形成覆盖程度在95％以上的绝缘层，还在具有正极极耳的第一侧面的除形成上述正极极耳的区域之外的所有区域形成覆盖程度在95％以上的绝缘层，因此能够包裹形成在第一侧面～第四侧面的毛刺，即包裹正极极片的所有裁切面的毛刺，进一步提高叠片式电池的安全性能。
在一些实施方式中，上述绝缘层从形成有上述绝缘层的侧面向与该侧面相连的端面上延伸，在与该侧面相连的端面上延伸的长度不大于0.5mm。
由此，形成在正极极片的侧面的绝缘层在与该侧面相连的端面上延伸，因此能够包裹从侧面向端面延伸的毛刺，防止因隔膜收缩等情况造成的短路，而且延伸长度不大于0.5mm，因此能够防止绝缘层过多而经由隔膜挤压负极极片，进一步提高叠片式电池的安全性能。
在一些实施方式中，上述绝缘层在形成有该绝缘层的侧面上的厚度为2～30μm。
由此，绝缘层在形成有该绝缘层的侧面上的厚度不小于2μm，因此能够防止毛刺较长时绝缘层过薄而不能完全包裹毛刺，并且绝缘层在形成有该绝缘层的侧面上的厚度不大于30μm，因此能够防止绝缘层过厚而脱落形成颗粒，提高叠片式电池的安全性能。
本申请的第二方面提供了一种正极极片，其设置在卷绕式电池中，包括：能够绕轴线方向卷绕成螺旋状的主体，其由正极活性物质层和正极集流体层叠而成，具有两个主面，两个上述主面是在上述正极活性物质层和上述正极集流体层叠的方向上相对的两个面；正极极耳，其由上述正极集流体从顶面沿上述轴线方向延伸到上述主体的外部而形成，上述顶面垂直于上述轴线方向并连接两个主面；和绝缘层，其形成在底面并覆盖上述底面的95％以上，上述底面在上述轴线方向上与上述顶面相对，垂直于上述轴线方向并连接两个主面。
本申请的能够设置于卷绕式电池中的正极极片具有顶面、底面和两个主面，顶面、底面均为裁切面，在顶面具有正极极耳，在底面具有覆盖该底面的95％以上的绝缘层。由此，形成在该底面的绝缘层能够包裹形成在底面的毛刺，防止由毛刺导致的短路，提高卷绕式电池的安全性能。另外，由于顶面具有正极极耳，在顶面形成绝缘层的方法较为复杂。因此，在底面形成覆盖程度在95％以上的绝缘层，并且在具有正极极耳的顶面不形成绝缘层，能够在提高卷绕式电池的安全性能的同时，提高卷绕式电池的生产效率。
在一些实施方式中，上述绝缘层从上述底面向与上述底面相连的主面上延伸，在与上述底面相连的主面上延伸的长度不大于0.5mm。
由此，形成在正极极片的底面的绝缘层在与该底面相连的主面上延伸，因此能够包裹从底面向主面延伸的毛刺，防止因隔膜收缩等情况造成的短路，而且延伸长度不大于0.5mm，因此能够防止绝缘层经由隔膜挤压负极极片，进一步提高卷绕式电池的安全性能。
在一些实施方式中，上述绝缘层在上述底面上的厚度为2～30μm。
由此，绝缘层在底面上的厚度不小于2μm，因此能够防止毛刺较长时绝缘层过薄而不能完全包裹毛刺，并且绝缘层在底面上的厚度不大于30μm，因此能够防止绝缘层过厚而脱落形成颗粒，提高卷绕式电池的安全性能。
在一些实施方式中，在上述底面的与两个上述主面相连的区域，分别设置有向上述顶面凹陷的两个削薄部，在上述削薄部设置有上述绝缘层。
由此，在底面的靠近两个主面的区域分别形成向顶面凹陷的削薄部，并在削薄部设置绝缘层，因此能够防止绝缘层在主面上延伸地过长而经由隔膜挤压负极极片，并且更好地包裹从底面向主面延伸的毛刺，进一步提高叠片式电池的安全性能。
在一些实施方式中，在上述削薄部的上述绝缘层和上述主体的厚度之和，不大于在上述削薄部之外的上述主体的厚度。
由此，削薄部的绝缘层不会突出到正极极片的主面之外，因此能够防止绝缘层经由隔膜挤压负极极片，进一步提高叠片式电池的安全性能。
在一些实施方式中，上述削薄部为长方体状，沿垂直于上述主面的方向的厚度在5μm以下，沿上述轴线方向的长度为0.5～5mm。
由此，使削薄部为长方体状，且沿垂直于主面的方向的厚度在5μm以下，沿轴线方向的长度为0.5～5mm，因此能够包裹从底面向主面延伸的毛刺，同时不占据主体部较多体积，保证电池的能量密度足够高。
关于本申请的第一方面和第二方面的正极极片，在一些实施方式中，上述绝缘层通过喷涂、点涂、浸涂中的一种方式实现。
由于在正极极片上预先形成绝缘层，因此绝缘层形成方法不会受到叠片式电池或卷绕式电池的结构妨碍，采用喷涂、点涂、浸涂中的一种方式即可，能够简化制造工艺。
关于本申请的第一方面和第二方面的正极极片，在一些实施方式中，制作上述绝缘层的陶瓷浆料至少包含陶瓷材料、粘结剂和溶剂，上述陶瓷材料占10～70wt％，上述粘结剂占1～5wt％，上述陶瓷浆料的粘度在100～1000mPa·s。
由此，利用至少包含陶瓷材料、粘结剂和溶剂的陶瓷浆料制作绝缘层，因此能够保证绝缘层的绝缘性和粘合性，并且陶瓷材料占10～70wt％，粘结剂占1～5wt％，陶瓷浆料的粘度在100～1000mPa·s，既不至于陶瓷材料过少而绝缘性不足，又不至于陶瓷材料过多而粘合性不够导致绝缘层脱落。
关于本申请的第一方面和第二方面的正极极片，在一些实施方式中，上述陶瓷材料为水合氧化铝、氧化镁、碳化硅和氮化硅中的一种，优选水合氧化铝；上述粘结剂为聚偏氟二乙烯、聚丙烯酸酯、丙烯酸甲酯、丙烯酸乙酯、2-甲基丙烯酸甲酯和2-甲基丙烯酸乙酯中的一种或几种的组合，优选聚偏氟二乙烯；上述溶剂为N-甲基吡咯烷酮。
由此，采用上述价格低廉且容易获得的材料，能够降低制造成本，有利于工业化生产。
本申请的第三方面提供了一种电池，其包括上述第一方面的正极极片、负极极片和隔膜，上述正极极片与上述负极极片在上述第一方向上交替地层叠，上述隔膜夹在上述正极极片与上述 负极极片之间。
本申请的第四方面提供了一种电池，其包括上述第二方面的正极极片、负极极片和隔膜，上述正极极片、上述负极极片和上述隔膜绕上述轴线方向卷绕，上述隔膜夹在上述正极极片与上述负极极片之间。
本申请的有益效果：
本申请提供的正极极片和电池，能够防止由毛刺导致的短路，提高电池的安全性能。
附图说明
图1是本申请的叠片式电池的正视图。
图2是本申请的一实施方式的叠片式电池的正极极片的立体图。
图3是本申请的一实施方式的叠片式电池的正极极片去掉绝缘层之后的立体图。
图4是本申请的另一实施方式的叠片式电池的正极极片的立体图。
图5是本申请的叠片式电池的正极极片的截面图。
图6是沿卷绕的轴线方向观察本申请的卷绕式电池的示意图。
图7是本申请的一实施方式的卷绕式电池的正极极片的截面图。
图8是本申请的另一实施方式的卷绕式电池的正极极片的截面图。
图9是本申请的又一实施方式的卷绕式电池的正极极片的截面图。
附图标记说明
1叠片式电池，11正极极片，12负极极片，13隔膜，111正极集流体，112正极活性物质层，113绝缘层，114正极极耳，11a、11b端面，11c第一侧面，11d第二侧面，11e第三侧面，11f第四侧面，2卷绕式电池，21正极极片，22负极极片，23隔膜，211正极集流体，212正极活性物质层，213绝缘层，214正极极耳，215削薄部，21a顶面，21b底面，21c、21d主面。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的正极极片和电池的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60～120和80～110的范围，理解为60～110和80～120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1～3、1～4、1～5、2～3、2～4和2～5。在本申请中，除非有其他说明，数值范围“a～b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0～5”表示本文中已经全部列出了“0～5”之间的全部实数，“0～5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，上述方法包括步骤(a)和(b)，表示上述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，提到上述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到上述方法，例如，上述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，上述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
发明人注意到，在叠片式锂离子电池和卷绕式锂离子电池这两种锂离子电池的制造过程中，都需要对极片进行裁切。极片由两层电极活性物质夹着集流体层叠而成，或者由一层电极活性物质层和集流体层叠而成，其中正极极片的集流体由金属箔(通常为铝箔)构成，在沿层叠方向进行裁切时，正极集流体容易产生毛刺。毛刺可能会刺穿夹在正极极片与负极极片之间的隔膜，导致毛刺与正极极片或负极极片接触而短路。另外，由于叠片式电池中容易发生的极片错位，或者卷绕时电池中的正极极片超出负极极片(overhang)的设计，导致正极极片超出负极极片而析锂，当存在毛刺时，毛刺很可能搭接到锂枝晶，存在短路失效风险。因此，毛刺会影响电池的安全性能。
现有技术中，对于Z形隔膜的叠片式电池，即隔膜是连续的，其中层叠后的正极极片和负极极片的一侧被隔膜包裹，因此无法通过喷涂、刷涂、点涂或浸涂的方式来完全包裹毛刺。另外，对于卷绕式电池，通过在卷绕好的正极极片、隔膜和负极极片的边缘涂胶以降低裁切边的毛刺概率，但隔膜长于负极极片且负极极片长于正极极片，即隔膜、正极极片、负极极片的边缘不在同一平面，因此难以通过喷涂、刷涂、点涂或浸涂的方式包裹正极极片裁切边的毛刺。
因此，本申请的第一方面提供了一种正极极片，其设置在叠片式电池中，包括：长方体状的主体，其由正极活性物质层和正极集流体在第一方向上层叠而成，具有四个侧面和两个端面，两个上述端面在上述第一方向上相对，上述四个侧面为上述第一侧面～上述第四侧面并分别沿上述第一方向连接两个上述端面；正极极耳，其由上述正极集流体从上述第一侧面延伸到上述主体的外部而形成；以及绝缘层，其形成在上述第二侧面～上述第四侧面，并覆盖上述第二侧面～上述第四侧面中的各侧面的95％以上。
本申请的能够设置于叠片式电池中的正极极片具有四个侧面，四个侧面均为裁切面，在第一侧面具有正极极耳，在第二侧面～第四侧面具有覆盖该第二侧面～第四侧面各自的95％以上的绝缘层。由此，形成在第二侧面～第四侧面的绝缘层能够包裹形成在第二侧面～第四侧面的毛刺，防止由毛刺导致的短路，提高叠片式电池的安全性能。另外，由于第一侧面具有正极极耳，在第一侧面形成绝缘层的方法较为复杂。因此，在第二侧面～第四侧面形成覆盖程度在95％以上的绝缘层，并且在具有正极极耳的第一侧面不形成绝缘层，能够在提高叠片式电池的安全性能的同时，提高叠片式电池的生产效率。
本申请的第二方面提供了一种正极极片，其设置在卷绕式电池中，包括：能够绕轴线方向卷绕成螺旋状的主体，其由正极活性物质层和正极集流体层叠而成，具有两个主面，两个上述主面是在上述正极活性物质层和上述正极集流体层叠的方向上相对的两个面；正极极耳，其由上述正极集流体从顶面沿上述轴线方向延伸到上述主体的外部而形成，上述顶面垂直于上述轴线方向并连接两个主面；和绝缘层，其形成在底面并覆盖上述底面的95％以上，上述底面在上述轴线方向上与上述顶面相对，垂直于上述轴线方向并连接两个主面。
本申请的能够设置于卷绕式电池中的正极极片具有顶面、底面和两个主面，顶面、底面均为裁切面，在顶面具有正极极耳，在底面具有覆盖该底面的95％以上的绝缘层。由此，形成在该底面的绝缘层能够包裹形成在底面的毛刺，防止由毛刺导致的短路，提高卷绕式电池的安全性能。另外，由于顶面具有正极极耳，在顶面形成绝缘层的方法较为复杂。因此，在底面形成覆盖程度在95％以上的绝缘层，并且在具有正极极耳的顶面不形成绝缘层，能够在提高卷绕式电池的安全性能的同时，提高卷绕式电池的生产效率。
本申请的第三方面提供了一种电池，其包括上述第一方面的正极极片、负极极片和隔膜，上述正极极片与上述负极极片在上述第一方向上交替地层叠，上述隔膜夹在上述正极极片与上述 负极极片之间。
本申请的第四方面提供了一种电池，其包括上述第二方面的正极极片、负极极片和隔膜，上述正极极片、上述负极极片和上述隔膜绕上述轴线方向卷绕，上述隔膜夹在上述正极极片与上述负极极片之间。
以下，参照附图，对本申请进行具体说明。
首先，对叠片式电池及其中的正极极片进行说明。图1是本申请的叠片式电池1的正视图。如图1所示，叠片式电池1包括正极极片11、负极极片12和隔膜13，正极极片11与负极极片12在第一方向Z上交替地层叠，隔膜13夹在正极极片11与负极极片12之间。
图2是本申请的一实施方式的叠片式电池1的正极极片11的立体图，图3是本申请的一实施方式的叠片式电池1的正极极片11去掉绝缘层113之后的立体图。在图2和图3中，正极极片11的第三侧面11e朝向纸面。如图2和图3所示，正极极片11包括长方体状的主体、正极极耳114和绝缘层113。长方体状的主体由正极活性物质层112正极集流体111在第一方向Z上层叠而成。正极活性物质层112可以为一层，也可以为两层。当正极活性物质层112为两层时，如图3所示，两层正极活性物质层112在第一方向Z上夹着正极集流体111。如图3所示，长方体状的主体具有四个侧面11c～11f和两个端面11a、11b。两个端面11a、11b在第一方向Z上相对。四个侧面11c～11f为第一侧面11c、第二侧面11d、第三侧面11e、第四侧面11f，并分别沿第一方向Z连接两个端面11a、11b。正极极耳114由正极集流体111从第一侧面11c延伸到主体的外部而形成。绝缘层113形成在第二侧面11d～第四侧面11f，并覆盖第二侧面11d～第四侧面11f中的各侧面的95％以上。图2中仅示出绝缘层113完全覆盖(覆盖程度100％)第二侧面11d～第四侧面11f的情况，但是不限于此，只要绝缘层113的覆盖程度在95％以上，就能实现包裹毛刺的效果。
正极极片11的四个侧面11c～11f均为裁切面，在第二侧面11d～第四侧面11f分别具有覆盖程度在95％以上的绝缘层113。由此，形成在第二侧面11d～第四侧面11f的绝缘层113能够包裹形成在第二侧面11d～第四侧面11f的毛刺，防止由毛刺导致的短路，提高叠片式电池1的安全性能。由于第一侧面11c具有正极极耳114，在第一侧面11c形成绝缘层113的方法较为复杂。因此，在第二侧面11d～第四侧面11f形成覆盖程度在95％以上的绝缘层113，并且在具有正极极耳114的第一侧面11c不形成绝缘层113，能够在提高叠片式电池1的安全性能的同时，提高叠片式电池1的生产效率。
图4是本申请的另一实施方式的叠片式电池1的正极极片11的立体图。在图4中，正极极片11的第一侧面11c朝向纸面。如图4所示，在一些实施方式中，绝缘层113还形成在第一侧面11c，并覆盖第一侧面11c中除形成正极极耳114的区域之外的所有区域的95％以上。图4中仅示出绝缘层113完全覆盖(覆盖程度100％)第一侧面11c中除形成正极极耳114的区域之外的所有区域的情况，但是不限于此，只要绝缘层113的覆盖程度在95％以上，就能实现包裹毛刺的效果。
由此，不仅在第二侧面11d～第四侧面11f形成覆盖程度在95％以上的绝缘层113，还在具有正极极耳114的第一侧面11c的除形成正极极耳114的区域之外的所有区域形成覆盖程度在95％以上绝缘层113，因此能够包裹形成在第一侧面11c～第四侧面11f的毛刺，即包裹正极极片11的所有裁切面的毛刺，进一步提高叠片式电池1的安全性能。
图5是本申请的叠片式电池1的正极极片11的截面图。如图2、图4和图5所示，在一些实施方式中，绝缘层113从形成有绝缘层113的侧面(图2中为第二侧面11d～第四侧面11f，图4中为第一侧面11c～第四侧面11f)向与该侧面相连的端面11a、11b上延伸，在与该侧面相连的端面11a、11b上延伸的长度W1不大于0.5mm。
由此，形成在正极极片11的侧面的绝缘层113在与该侧面相连的端面上延伸，因此能够包裹从侧面向端面延伸的毛刺，防止因隔膜13收缩等情况造成的短路，而且延伸长度不大于0.5mm，因此能够防止绝缘层113经由隔膜13挤压负极极片12，进一步提高叠片式电池1的安全性能。
如图5所示，在一些实施方式中，绝缘层113在形成有该绝缘层113的侧面上的厚度D1为2～30μm。
由此，绝缘层113在形成有该绝缘层113的侧面上的厚度不小于2μm，因此能够防止毛刺较长时绝缘层113过薄而不能完全包裹毛刺，并且绝缘层113在形成有该绝缘层113的侧面上的厚度不大于30μm，因此能够防止绝缘层113过厚而脱落形成颗粒，提高叠片式电池1的安全性能。
接着，对卷绕式电池及其中的正极极片进行说明。图6是沿卷绕的轴线方向AX观察本申请的卷绕式电池2的示意图。如图6所示，卷绕式电池2包括正极极片21、负极极片22和隔膜23。正极极片、负极极片22和隔膜23绕轴线方向AX卷绕。隔膜23夹在正极极片与负极极片22之间。
图7是本申请的一实施方式的卷绕式电池2的正极极片21的截面图。正极极片21包括主 体、正极极耳214和绝缘层213。主体能够绕轴线方向AX卷绕成螺旋状，由正极活性物质层212和正极集流体211层叠而成，具有两个主面21c、21d。主面21c、21d是在正极活性物质层212和正极集流体211层叠的方向上相对的两个面。正极活性物质层212可以为一层，也可以为两层。当正极活性物质层112为两层时，如图7～9所示，两层正极活性物质层212夹着正极集流体211层叠，并且主面21c、21d由正极活性物质层212的远离正极集流体211的面构成。正极极耳214由正极集流体211从顶面21a沿轴线方向AX延伸到主体的外部而形成。顶面21a垂直于轴线方向AX并连接两个主面21c、21d。绝缘层213形成在底面21b并覆盖底面21b的95％以上。底面21b在轴线方向AX上与顶面21a相对，垂直于轴线方向AX并连接两个主面21c、21d。图7中仅示出绝缘层213完全覆盖(覆盖程度100％)底面21b的情况，但是不限于此，只要绝缘层213的覆盖程度在95％以上，就能实现包裹毛刺的效果。
卷绕式电池2中的正极极片21具有顶面21a、底面21b和两个主面21c、21d，其中，顶面21a、底面21b均为裁切面。在顶面21a具有正极极耳214，在底面21b具有覆盖该底面21b的95％以上的绝缘层213。由此，形成在该底面21b的绝缘层213能够包裹形成在底面21b的毛刺，防止由毛刺导致的短路，提高卷绕式电池的安全性能。另外，由于顶面21a具有正极极耳214，在顶面21a形成绝缘层213的方法较为复杂。因此，在底面21b形成覆盖程度在95％以上的绝缘层213，并且在具有正极极耳214的顶面21a不形成绝缘层213，能够在提高卷绕式电池的安全性能的同时，提高卷绕式电池的生产效率。
图8是本申请的另一实施方式的卷绕式电池2的正极极片21的截面图。如图8所示，在一些实施方式中，绝缘层213还形成在顶面21a，并覆盖顶面21a中除形成正极极耳214的区域之外的所有区域的95％以上。图8中仅示出绝缘层213完全覆盖(覆盖程度100％)顶面21a中除形成正极极耳214的区域之外的所有区域的情况，但是不限于此，只要绝缘层213的覆盖程度在95％以上，就能实现包裹毛刺的效果。
由此，不仅在底面21b形成覆盖程度在95％以上的绝缘层213，还在具有正极极耳214的顶面21a的除形成正极极耳214的区域之外的所有区域形成覆盖程度在95％以上的绝缘层213，因此能够包裹形成在顶面21a和底面21b的毛刺，即包裹正极极片21的所有裁切面的毛刺，进一步提高卷绕式电池的安全性能。
如图7所示，在一些实施方式中，绝缘层213从底面21b向与底面21b相连的主面21c、21d上延伸，在与底面21b相连的主面21c、21d上延伸的长度W2不大于0.5mm。
由此，形成在正极极片21的底面21b的绝缘层213在与该底面21b相连的主面21c、21d上延伸，因此能够包裹从底面21b向主面21c、21d延伸的毛刺，防止因隔膜23收缩等情况造成的短路，而且延伸长度不大于0.5mm，因此能够防止绝缘层213经由隔膜23挤压负极极片22，进一步提高卷绕式电池的安全性能。
如图7所示，在一些实施方式中，绝缘层213在底面21b上的厚度D2为2～30μm。
由此，绝缘层213在底面21b上的厚度不小于2μm，因此能够防止毛刺较长时绝缘层213过薄而不能完全包裹毛刺，并且绝缘层213在底面21b上的厚度不大于30μm，因此能够防止绝缘层213过厚而脱落形成颗粒，提高卷绕式电池的安全性能。
图9是本申请的又一实施方式的卷绕式电池2的正极极片21的截面图。如图9所示，在一些实施方式中，在底面21b的与两个主面21c、21d相连的区域，分别设置有向顶面21a凹陷的两个削薄部215，在削薄部215设置有绝缘层213。
由此，在底面21b的靠近两个主面21c、21d的区域分别形成向顶面21a凹陷的削薄部215，并在削薄部215设置绝缘层213，因此能够防止绝缘层213在主面21c、21d上延伸地过长而经由隔膜23挤压负极极片22，并且更好地包裹从底面21b向主面21c、21d延伸的毛刺，进一步提高叠片式电池1的安全性能。
如图9所示，在一些实施方式中，在削薄部215的绝缘层213和主体(包括正极活性物质层212和正极集流体211)的厚度之和H2，不大于在削薄部215之外的主体(包括正极活性物质层212和正极集流体211)的厚度H3。
由此，削薄部215的绝缘层213不会突出到正极极片21的主面21c、21d之外，因此能够防止绝缘层213经由隔膜23挤压负极极片22，进一步提高叠片式电池1的安全性能。
如图9所示，在一些实施方式中，削薄部215为长方体状，沿垂直于主面21c、21d的方向的厚度H1在5μm以下，沿轴线方向AX的长度L1为0.5～5mm。
由此，使削薄部215为长方体状，且沿垂直于主面21c、21d的方向的厚度在5μm以下，沿轴线方向AX的长度为0.5～5mm，因此能够包裹从底面21b向主面21c、21d延伸的毛刺，同时不占据主体部较多体积，保证电池的能量密度足够高。
在一些实施方式中，在正极极片11、21中，绝缘层113、213通过喷涂、点涂、浸涂中的一种方式实现。
由此，由于在正极极片11、21上预先形成绝缘层113、213，因此绝缘层113、213形成方法不会受到叠片式电池1或卷绕式电池2的结构妨碍，采用喷涂、点涂、浸涂中的一种方式即可，能够简化制造工艺。
在一些实施方式中，在正极极片11、21中，制作绝缘层113、213的陶瓷浆料至少包含陶瓷材料、粘结剂和溶剂，陶瓷材料占10～70wt％，粘结剂占1～5wt％，陶瓷浆料的粘度在100～1000mPa·s。
由此，利用至少包含陶瓷材料、粘结剂和溶剂的陶瓷浆料制作绝缘层113、213，因此能够保证绝缘层113、213的绝缘性和粘合性，并且陶瓷材料占10～70wt％，粘结剂占1～5wt％，陶瓷浆料的粘度在100～1000mPa·s，既不至于陶瓷材料过少而绝缘性不足，又不至于陶瓷材料过多而粘合性不够导致绝缘层113、213脱落。
在一些实施方式中，陶瓷材料为水合氧化铝、氧化镁、碳化硅和氮化硅中的一种，优选水合氧化铝。粘结剂为聚偏氟二乙烯、聚丙烯酸酯、丙烯酸甲酯、丙烯酸乙酯、2-甲基丙烯酸甲酯和2-甲基丙烯酸乙酯中的一种或几种的组合，优选聚偏氟二乙烯。溶剂为N-甲基吡咯烷酮。
由此，采用价格低廉且容易获得的材料，能够降低制造成本，有利于工业化生产。
[实施例]
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
(实施例1)
1.正极极片的制备
将正极活性材料涂布在正极集流体两面，经冷压、裁切后，得到多个裁切面(第一侧面～第四侧面)存在毛刺的正极极片的主体，将这些正极极片主体堆叠，在第一侧面～第四侧面喷涂陶瓷浆料，除正极极耳部位之外，完全覆盖(覆盖程度100％)第一侧面～第四侧面，且向端面延伸长度不大于0.5mm，然后进行干燥，得到正极极片。在陶瓷浆料中，陶瓷材料占60wt％，粘结剂占5wt％，陶瓷浆料的粘度在800mPa·s。绝缘层厚度10μm，向正极极片的端面上延伸的长度不大于0.5mm。
2.负极极片的制备
将负极活性材料涂布在负极集流体两面，经冷压、裁切后，得到负极极片。
3.隔膜
采用连续的隔膜。
4.组装
使用装配夹具，将隔膜Z形折叠，按照“隔膜-负极极片-隔膜-正极极片-隔膜-负极极片……”的顺序进行组装，得到实施例1的叠片式电池。其中，采用了正极极片超出负极极片的设计。
(实施例2)
除不在设有正极极耳的第一侧面涂布绝缘层之外，以与实施例1同样的方式，得到实施例2的叠片式电池。
(对比例1)
除不在正极极片涂布绝缘层之外，以与实施例1同样的方式，得到对比例1的叠片式电池。
(对比例2)
除绝缘层的厚度为1μm之外，以与实施例1同样的方式，得到对比例2的叠片式电池。
上述实施例1、实施例2、对比例1和对比例2的叠片式电池各制作100个，对这些叠片式电池进行绝缘耐压测试(Hi-pot测试)，来检测是否存在毛刺刺穿隔膜的情况。统计未通过绝缘耐压测试的电池的个数，计算其占总个数的百分比，记录在表1中的毛刺刺穿隔膜的概率栏中。另外，对于上述实施例1、实施例2、对比例1和对比例2的叠片式电池，再分别制作10个，设计成正极极片超出负极极片(overhang)对于overhang设计的叠片式电池。由于该设计会加速析锂，因此通过对这些叠片式电池进行循环充放电，来检测锂枝晶与毛刺或漏铝(漏出的正极集流体)搭接的情况。统计循环充电过程中失效的电池的个数，计算其占总个数的百分比，记录在表1中的毛刺刺穿隔膜的概率栏和毛刺搭接锂枝晶后的失效概率栏中。
Figure PCTCN2022122826-appb-000001
表1为叠片式电池的评价结果。根据表1可知，当在正极极片的裁切面没有设置绝缘层时，如对比例1，裁切面的毛刺裸露在外，毛刺刺破隔膜的风险极高，概率达到75％，同时因正极极片超出负极极片导致的析锂与毛刺或漏铝搭接引起的循环充电失效风险也最大，10个叠片式电池全部失效。当在正极极片的四个裁切面即第一侧面～第四侧面涂布绝缘层，但绝缘层的厚度过低时，如对比例2，陶瓷涂层无法完全包裹毛刺，依然无法将毛刺刺破隔膜导致的短路风险和循环充电失效风险降低到理想程度。而如本申请的实施例1，在叠片式电池的正极极片的四个裁切面即第一侧面～第四侧面均涂布一定厚度的绝缘层后，会将毛刺刺破隔膜导致的短路风险和循环充电失效风险降至最低。叠片式电池的第一侧面具有向主体外部突出的正极极耳，在第一侧面涂布绝缘层时，工艺较为复杂，影响生产效率。如实施例2，在除了第一侧面之外的其他裁切面即第二侧面～第四侧面涂布绝缘层，也能起到较好的降低毛刺刺破隔膜导致的短路风险和循环充电失效风险的效果，同时兼顾了生产效率。
(实施例3)
1.正极极片的制备
将正极活性材料涂布在正极集流体两面，经冷压、裁切后，得到多个裁切面(顶面和底面)存在毛刺的正极极片的主体，将这些正极极片主体堆叠，在顶面和底面喷涂陶瓷浆料，除正极极耳部位之外，完全覆盖(覆盖程度100％)顶面和底面，且向主面延伸长度不大于0.5mm，然后进行干燥，得到正极极片。在陶瓷浆料中，陶瓷材料占60wt％，粘结剂占5wt％，陶瓷浆料的粘度在800mPa·s。裁切面的绝缘层厚度10μm，向正极极片的主面上延伸的长度不大于0.5mm。
2.负极极片的制备
将负极活性材料涂布在负极集流体两面，经冷压、裁切后，得到负极极片。
3.卷绕
按照“隔膜-负极极片-隔膜-正极极片”的顺序放置，正极极片、负极极片和两个隔膜的一端固定在出料辊，另一端层叠在一起后固定在卷绕轴。利用电机使卷绕轴转动，对正极极片、负极极片和两个隔膜进行卷绕，得到实施例3的卷绕式电池。
(实施例4)
除不在设有正极极耳的顶面涂布绝缘层之外，以与实施例3同样的方式，得到实施例4的卷绕式电池。
(实施例5)
不在设有正极极耳的顶面涂布绝缘层，并且在底面形成设置有绝缘层的削薄部，削薄部沿轴线方向的长度为5mm，削薄部处的绝缘层厚度为5μm。除此以外，以与实施例3同样的方式，得到实施例5的卷绕式电池。
(对比例3)
除不在正极极片涂布绝缘层之外，以与实施例3同样的方式，得到对比例3的卷绕式电池。
(对比例4)
不在设有正极极耳的顶面涂布绝缘层，并且在底面形成设置有绝缘层的削薄部，削薄部沿轴线方向的长度为5mm，削薄部处的绝缘层厚度为2μm。除此以外，以与实施例3同样的方式，得到对比例4的卷绕式电池。
(对比例5)
不在设有正极极耳的顶面涂布绝缘层，并且在底面形成设置有绝缘层的削薄部，削薄部沿轴线方向的长度为5mm，削薄部处的绝缘层厚度为10μm，底面的绝缘层厚度为1μm。除此以外，以与实施例3同样的方式，得到对比例5的卷绕式电池。
上述实施例3～实施例5和对比例3～对比例5的卷绕式电池各制作100个，对这些卷绕式电池进行绝缘耐压测试(Hi-pot测试)，来检测是否存在毛刺刺穿隔膜的情况。统计未通过绝缘耐压测试的电池的个数，计算其占总个数的百分比，记录在表2中的毛刺刺穿隔膜的概率栏中。另外，对于上述实施例3～实施例5和对比例3～对比例5的卷绕式电池，再分别制作10个，设计成正极极片超出负极极片(overhang)。由于该设计会加速析锂，因此通过对这些卷绕式电池进行循环充放电，来检测锂枝晶与毛刺或漏铝(漏出的正极集流体)搭接的情况。统计循环充电过程中失效的电池的其个数，计算其占总个数的百分比，记录在表2中的毛刺搭接锂枝晶后的失效概率栏中。另外，还以对比例3为基准，采用公知的方法计算实施例3～实施例5和对比例4～对比例5的(体积)能量密度的百分比，记录在表2的能量密度中。
Figure PCTCN2022122826-appb-000002
表2为卷绕式电池的评价结果。根据表2可知，当在正极极片的裁切面即顶面和底面未设置绝缘层时，如对比例3，裁切边的毛刺刺破隔膜概率极高，因毛刺刺破隔膜导致的短路风险最大，且锂枝晶搭接毛刺后发生的循环充电失效风险也最大。当在正极极片顶面和底面附着绝缘层，且绝缘层向主面延伸的长度不超过0.5mm时，如实施例3，毛刺刺穿隔膜的概率极低，毛刺刺破隔膜导致的短路风险极大，且循环充电失效风险极小。当只在正极极片底面附着绝缘层，且绝缘层向主面延伸的长度不大于0.5mm时，如实施例4，毛刺刺穿隔膜的概率也很低，循环充电失效风险小。当正极极片的底面没有设置削薄部，且绝缘层向主面延伸的长度大于0.5mm时，随着正极极片、负极极片和两个隔膜卷绕后，绝缘层在主面的靠近底面的区域受压而条状突起，对负极极片造成一定挤压而损伤负极极片，如对比例4。针对该情况下，当在正极极片的底面设置削薄部，削薄部的厚度大于设置在削薄部的绝缘层的厚度时，电池的能量密度虽有一定程度的损失，但对于隔膜收缩或正极极片超出负极极片造成不良等的情况，削薄部的绝缘层可以有效防止正极极片与负极极片直接搭接而造成短路，并且有效防止锂枝晶搭接毛刺后发生循环充电失效，如实施例5。虽然在削薄部的长度即在主面上的长度越长，对于防护正极极片与负极极片搭接造成的短路越有效，但是电池的能量密度损失也越大，如对比例5。
另外，除了改变绝缘层的覆盖程度，例如改变至95％、98％之外，以与上述实施例1～5和上述对比例1～5同样的方式制作了叠片式电池和卷绕式电池，并按表1和表2的评价方式进行了评价。其结果是，实施例的绝缘层的覆盖程度分别在95％和98％时，毛刺刺破隔膜导致的短路风险相比于覆盖程度100％时略有升高，毛刺刺破隔膜的概率在15％以下，毛刺搭接锂枝晶后的失效概率在1/10以下，都在能够充分保证电池安全性的范围内。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (21)

  1. 一种正极极片，其中，
    所述正极极片设置在叠片式电池中，包括：
    长方体状的主体，其由正极活性物质层和正极集流体在第一方向上层叠而成，具有四个侧面和两个端面，两个所述端面在所述第一方向上相对，所述四个侧面为所述第一侧面～所述第四侧面并分别沿所述第一方向连接两个所述端面；
    正极极耳，其由所述正极集流体从所述第一侧面延伸到所述主体的外部而形成；以及
    绝缘层，其形成在所述第二侧面～所述第四侧面，覆盖所述第二侧面～所述第四侧面中的各侧面的95％以上。
  2. 根据权利要求1所述的正极极片，其中，
    所述绝缘层还形成在所述第一侧面，并覆盖所述第一侧面中除形成所述正极极耳的区域之外的所有区域的95％以上。
  3. 根据权利要求1～2中任一项所述的正极极片，其中，
    所述绝缘层从形成有所述绝缘层的侧面向与该侧面相连的端面上延伸，在与该侧面相连的端面上延伸的长度不大于0.5mm。
  4. 根据权利要求1～3中任一项所述的正极极片，其中，
    所述绝缘层在形成有该绝缘层的侧面上的厚度为2～30μm。
  5. 根据权利要求1～4中任一项所述的正极极片，其中，
    所述绝缘层通过喷涂、点涂、浸涂中的一种方式实现。
  6. 根据权利要求1～5中任一项所述的正极极片，其中，
    制作所述绝缘层的陶瓷浆料至少包含陶瓷材料、粘结剂和溶剂，所述陶瓷材料占10～70wt％，所述粘结剂占1～5wt％，所述陶瓷浆料的粘度在100～1000mPa·s。
  7. 根据权利要求6所述的正极极片，其中，
    所述陶瓷材料为水合氧化铝、氧化镁、碳化硅和氮化硅中的一种，所述粘结剂为聚偏氟二乙烯、聚丙烯酸酯、丙烯酸甲酯、丙烯酸乙酯、2-甲基丙烯酸甲酯和2-甲基丙烯酸乙酯中的一种或几种的组合，所述溶剂为N-甲基吡咯烷酮。
  8. 根据权利要求7所述的正极极片，其中，
    所述陶瓷材料为水合氧化铝，所述粘结剂为聚偏氟二乙烯。
  9. 一种正极极片，其中，
    所述正极极片设置在卷绕式电池中，包括：
    能够绕轴线方向卷绕成螺旋状的主体，其由正极活性物质层和正极集流体层叠而成，具有两个主面，两个所述主面是在所述正极活性物质层和所述正极集流体层叠的方向上相对的两个面；
    正极极耳，其由所述正极集流体从顶面沿所述轴线方向延伸到所述主体的外部而形成，所述顶面垂直于所述轴线方向并连接两个主面；和
    绝缘层，其形成在底面并覆盖所述底面的95％以上，所述底面在所述轴线方向上与所述顶面相对，垂直于所述轴线方向并连接两个主面。
  10. 根据权利要求9所述的正极极片，其中，
    所述绝缘层还形成在所述顶面，并覆盖所述顶面中除形成所述正极极耳的区域之外的所有区域的95％以上。
  11. 根据权利要求9～10中任一项所述的正极极片，其中，
    所述绝缘层从所述底面向与所述底面相连的主面上延伸，在与所述底面相连的主面上延伸的长度不大于0.5mm。
  12. 根据权利要求9～11中任一项所述的正极极片，其中，
    所述绝缘层在所述底面上的厚度为2～30μm。
  13. 根据权利要求9～12中任一项所述的正极极片，其中，
    在所述底面的与两个所述主面相连的区域，分别设置有向所述顶面凹陷的两个削薄部，
    在所述削薄部设置有所述绝缘层。
  14. 根据权利要求13所述的正极极片，其中，
    在所述削薄部的所述绝缘层和所述主体的厚度之和，不大于在所述削薄部之外的所述主体的厚度。
  15. 根据权利要求13所述的正极极片，其中，
    所述削薄部为长方体状，沿垂直于所述主面的方向的厚度在5μm以下，沿所述轴线方向的 长度为0.5～5mm。
  16. 根据权利要求9～15中任一项所述的正极极片，其中，
    所述绝缘层通过喷涂、点涂、浸涂中的一种方式实现。
  17. 根据权利要求9～16中任一项所述的正极极片，其中，
    制作所述绝缘层的陶瓷浆料至少包含陶瓷材料、粘结剂和溶剂，所述陶瓷材料占10～70wt％，所述粘结剂占1～5wt％，所述陶瓷浆料的粘度在100～1000mPa·s。
  18. 根据权利要求17所述的正极极片，其中，
    所述陶瓷材料为水合氧化铝、氧化镁、碳化硅和氮化硅中的一种，所述粘结剂为聚偏氟二乙烯、聚丙烯酸酯、丙烯酸甲酯、丙烯酸乙酯、2-甲基丙烯酸甲酯和2-甲基丙烯酸乙酯中的一种或几种的组合，所述溶剂为N-甲基吡咯烷酮。
  19. 根据权利要求18所述的正极极片，其中，
    所述陶瓷材料为水合氧化铝，所述粘结剂为聚偏氟二乙烯。
  20. 一种电池，其中，
    包括权利要求1～8中任一项所述的正极极片、负极极片和隔膜，
    所述正极极片与所述负极极片在所述第一方向上交替地层叠，
    所述隔膜夹在所述正极极片与所述负极极片之间。
  21. 一种电池，其中，
    包括权利要求9～19中任一项所述的正极极片、负极极片和隔膜，
    所述正极极片、所述负极极片和所述隔膜绕所述轴线方向卷绕，
    所述隔膜夹在所述正极极片与所述负极极片之间。
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CN117352665A (zh) * 2023-12-05 2024-01-05 时代广汽动力电池有限公司 一种锂电池极片绝缘层减薄工艺
CN117352665B (zh) * 2023-12-05 2024-02-27 时代广汽动力电池有限公司 一种锂电池极片绝缘层减薄工艺

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