WO2023164794A1 - 电化学装置及包含该电化学装置的电子装置 - Google Patents

电化学装置及包含该电化学装置的电子装置 Download PDF

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WO2023164794A1
WO2023164794A1 PCT/CN2022/078573 CN2022078573W WO2023164794A1 WO 2023164794 A1 WO2023164794 A1 WO 2023164794A1 CN 2022078573 W CN2022078573 W CN 2022078573W WO 2023164794 A1 WO2023164794 A1 WO 2023164794A1
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lithium
electrochemical device
positive electrode
negative electrode
active material
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French (fr)
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陈佳
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to PCT/CN2022/078573 priority Critical patent/WO2023164794A1/zh
Priority to CN202280003780.8A priority patent/CN115516681B/zh
Priority to EP22929247.9A priority patent/EP4489109A4/en
Publication of WO2023164794A1 publication Critical patent/WO2023164794A1/zh
Priority to US18/820,917 priority patent/US20240429398A1/en
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    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
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    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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

Definitions

  • the present application relates to the field of electrochemical technology, in particular to an electrochemical device and an electronic device including the electrochemical device.
  • secondary batteries such as lithium-ion batteries
  • secondary batteries have the advantages of high energy storage density, high open circuit voltage, low self-discharge rate, long cycle life, and good safety performance.
  • portable small electronic equipment such as cameras, cameras, and large-scale electric transport work and renewable energy storage.
  • electronic products such as disposable electronic cigarettes that only require a small number of charge-discharge cycles have lower requirements on the cycle life of secondary batteries. Therefore, how to obtain market competitiveness by reducing the production cost of such secondary batteries has become an essential Technical problems to be solved urgently by those skilled in the art.
  • the present application provides an electrochemical device and an electronic device including the electrochemical device, so as to reduce the production cost of the electrochemical device.
  • the present application is explained by taking the lithium-ion battery as an example of the electrochemical device, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • the first aspect of the present application provides an electrochemical device, including a positive pole piece and a negative pole piece; the positive pole piece includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the The positive electrode active material layer includes a lithium-containing positive electrode active material; the negative electrode sheet includes a negative electrode current collector and ceramic coatings arranged on both surfaces of the negative electrode current collector, and the negative electrode sheet also includes the lithium-containing Lithium ions in the positive electrode active material are deposited on the surface of the negative electrode current collector to form a lithium metal layer during charging, and the lithium metal layer is located between the negative electrode current collector and the ceramic coating; the negative electrode The sheet does not contain negative active material.
  • the negative electrode plate is not provided with negative active materials, but is provided with ceramic coatings on the two surfaces of the negative electrode current collector in the thickness direction.
  • the ceramic coatings can promote Li in the charging process of the electrochemical device.
  • the uniform deposition of ions (Li + ) on the negative electrode current collector forms a lithium metal layer, so that the lithium metal layer is formed between the negative electrode current collector and the ceramic coating, and the lithium metal layer is uniform and dense, and the ceramic coating can also absorb lithium. Dendrite.
  • the thickness space originally occupied by the negative electrode active material is saved, and the saved thickness space can meet the energy density of the electrochemical device by adding a low-cost positive electrode active material on the positive electrode sheet.
  • the cost of the ceramic coating is lower than that of the negative electrode active material layer. Therefore, the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the electrochemical device further includes an electrolyte, which includes fluoroethylene carbonate and lithium difluorooxalate borate; based on the quality of the electrolyte, the fluoroethylene carbonate
  • the mass percentage W 1 of the ester is 0.1% to 10%
  • the mass percentage W 2 of the lithium difluorooxalate borate is 0.05% to 5%.
  • the electrolyte in the electrochemical device includes fluoroethylene carbonate and lithium difluorooxalate borate, and the mass percentage content of fluoroethylene carbonate and lithium difluorooxalate borate is regulated within the above range, which is beneficial to the negative electrode
  • a better solid electrolyte interface (SEI) film is formed on the surface of the pole piece, which is conducive to the uniform deposition of Li + on the negative electrode current collector, forming a dense and uniform lithium metal layer, thereby realizing the reversibility and stability of lithium metal layer plating, Satisfy the cycle performance of the electrochemical device. Therefore, the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the positive electrode active material containing lithium includes at least one of lithium cobaltate, lithium manganate, lithium nickel cobalt manganate, lithium titanate or lithium fluoride.
  • the positive electrode active material layer further includes a positive electrode lithium replenishing agent
  • the positive electrode lithium replenishing agent includes at least one of Li 2 O or Li x MO y , 2 ⁇ x ⁇ 6, 2 ⁇ y ⁇ 4, M includes at least one of Al, Ni, Co, Mg, Mn, Cu, Fe or Ti; based on the mass of the positive electrode active material layer, the mass percentage of the positive electrode lithium replenishing agent W 3 is 3% to 10%.
  • the electrochemical device can offset the irreversible loss of lithium in the electrochemical device with no negative electrode active material during the long-term cycle, and realize the reversibility and stability of lithium metal layer plating, thereby improving the electrochemical device. cycle performance.
  • the electrochemical device can further improve the cycle performance of the electrochemical device while reducing the production cost.
  • the positive electrode active material layer further includes a positive electrode additive
  • the positive electrode additive includes a composite material formed of an inorganic lithium salt and a first conductive agent, and the inorganic lithium salt and the first conductive agent
  • the mass ratio of the positive electrode additive is 1:3 to 1:7; based on the positive electrode active material layer, the mass percentage W 4 of the positive electrode additive is 4% to 8%.
  • the selection of the above-mentioned positive electrode additive, and the mass percentage content W4 of the positive electrode additive in the positive electrode active material layer are regulated in the above-mentioned range, can release more Li in the charge-discharge cycle process of the electrochemical device to provide additional Lithium source, improve the first discharge capacity of the electrochemical device, reduce the charge transfer resistance of the electrochemical device, and improve the energy density, cycle performance and rate performance of the electrochemical device.
  • the irreversible loss of lithium in the initial anode-free electrochemical device can be offset, and the reversibility and stability of the lithium metal layer plating can be realized, thereby improving the cycle performance of the electrochemical device.
  • the energy density, cycle performance and rate capability of the electrochemical device can be further improved while reducing the production cost.
  • the inorganic lithium salt includes Li s Q a N b O t , 2 ⁇ s ⁇ 8, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, a+b ⁇ 1, 2 ⁇ t ⁇ 6, Q is selected from Fe, Co, Mn, Ni, Zr, V, Nb or Mo, and N is selected from Al, Mg, Ti, Cr, Y, Sr, Si, W, Ga or Zn Any one of them; the first conductive agent includes at least one of graphene, acetylene black, single-walled carbon nanotubes or multi-walled carbon nanotubes.
  • the selection of the above-mentioned inorganic lithium salt and the first conductive agent is more conducive to further improving the cycle performance of the electrochemical device while reducing the production cost.
  • the positive pole piece further includes the ceramic coating, and the ceramic coating is disposed on the surface of the positive active material layer.
  • the ceramic coating is arranged on the surface of the positive electrode active material layer, which is more conducive to preventing the lithium dendrites precipitated from the negative electrode sheet from inserting into the positive electrode sheet, thereby improving the safety performance and thermal stability of the electrochemical device.
  • the ceramic coating includes inorganic powder and a first binder; based on the mass of the ceramic coating, the mass percentage W of the inorganic powder is 85 % to 95%, the mass percentage W 6 of the first binder is 5% to 15%.
  • the above materials are selected to form the ceramic coating, and the mass percentages of the inorganic powder and the first binder in the ceramic coating are controlled within the above range, which is more conducive to the function of the ceramic coating. In this way, the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the inorganic powder includes at least one of alumina, magnesia, zirconia or boehmite
  • the first binder includes polyacrylic acid, polyvinylidene fluoride, poly At least one of imide or polyvinyl alcohol.
  • the thickness of the ceramic coating is 1 ⁇ m to 3 ⁇ m. Regulating the thickness of the ceramic coating within the above range enables the role of the ceramic coating in this application to be effectively brought into play. As a result, the electrochemical device has lower material production costs while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the negative electrode sheet further includes a conductive layer, the conductive layer is disposed between the negative electrode current collector and the ceramic coating, and the lithium metal layer is disposed on the negative electrode current collector. between the fluid and the conductive layer.
  • the setting of the conductive layer can receive the Li + released from the positive pole piece, inhibit the formation of lithium precipitation and dead lithium, thereby improving the safety performance and cycle performance of the electrochemical device.
  • the conductive layer includes a second conductive agent and a second binder; based on the mass of the conductive layer, the mass percentage W of the second conductive agent is 60 % to 70%, the mass percentage W 8 of the second binder is 30% to 40%.
  • the second conductive agent includes at least one of amorphous carbon, single-walled carbon nanotubes, or multi-walled carbon nanotubes;
  • the second binder includes styrene-butadiene rubber, carboxylate At least one of methylcellulose or polyvinyl alcohol.
  • the above-mentioned materials are selected to form the conductive layer, and the mass percentages of the second conductive agent and the second binder are controlled within the above-mentioned range, which is more conducive to the function of the conductive layer.
  • the conductive layer can receive the Li + released from the positive pole piece, inhibit lithium precipitation and the formation of dead lithium, thereby improving the safety performance and cycle performance of the electrochemical device.
  • a second aspect of the present application provides an electronic device, which includes the electrochemical device described in any one of the foregoing embodiments.
  • a ceramic coating is provided on both surfaces of the negative electrode current collector in the thickness direction instead of a negative electrode active material on the negative electrode sheet.
  • the ceramic coating can promote Li + during the charging process of the electrochemical device.
  • the uniform deposition on the negative electrode current collector forms a lithium metal layer, so that the lithium metal layer is formed between the negative electrode current collector and the ceramic coating.
  • the lithium metal layer is uniform and dense, and the ceramic coating can also absorb lithium dendrites.
  • the thickness space originally occupied by the negative electrode active material is saved, and the saved thickness space can meet the energy density of the electrochemical device by adding a low-cost positive electrode active material on the positive electrode sheet.
  • the cost of the ceramic coating is lower than that of the negative electrode active material layer. Therefore, the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • FIG. 1 is a schematic cross-sectional structure diagram of an electrochemical device according to some embodiments of the present application.
  • Fig. 2 is a schematic cross-sectional structure diagram of the positive pole piece in some embodiments of the present application.
  • Fig. 3 is a schematic cross-sectional structure diagram of the negative electrode sheet in some embodiments of the present application.
  • a lithium-ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to the lithium-ion battery.
  • the first aspect of the present application provides an electrochemical device, including a positive pole piece and a negative pole piece; the positive pole piece includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, and the positive active material layer includes The positive electrode active material of lithium;
  • the negative electrode sheet includes the negative electrode collector and the ceramic coating arranged on the two surfaces of the negative electrode collector, and the negative electrode sheet also includes lithium ions in the positive electrode active material containing lithium.
  • the lithium metal layer is deposited on the surface of the fluid, and the lithium metal layer is located between the negative electrode current collector and the ceramic coating; the negative electrode sheet does not contain negative electrode active materials.
  • the negative electrode plate is not provided with negative active materials, but is provided with ceramic coatings on the two surfaces of the negative electrode current collector in the thickness direction.
  • the ceramic coatings can promote Li in the charging process of the electrochemical device. +
  • the uniform deposition on the negative electrode current collector forms a lithium metal layer, so that the lithium metal layer is formed between the negative electrode current collector and the ceramic coating.
  • the lithium metal layer is uniform and dense, and the ceramic coating can also absorb lithium dendrites.
  • the thickness space occupied by the negative electrode active material is saved (in the prior art, the thickness of the negative electrode active material layer containing the negative electrode active material is usually greater than 100 ⁇ m), and the thickness space saved can be increased by adding a low Valence positive electrode active materials to meet the energy density of electrochemical devices. Also, the cost of the ceramic coating is lower than that of the negative electrode active material layer. Therefore, the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the positive electrode current collector includes two opposite first surfaces and second surfaces in the thickness direction, the above-mentioned "positive electrode active material layer disposed on at least one surface of the positive electrode current collector” should be understood by those skilled in the art,
  • the positive electrode active material layer can be provided on the first surface, or on the second surface, or on both the first surface and the second surface, and those skilled in the art can choose according to actual needs.
  • the above-mentioned “surface” may be the entire area of the first surface and/or the second surface, or a partial area of the first surface and/or the second surface. This application is not particularly limited, as long as the application can realize purpose. It should be understood that "the negative electrode sheet does not contain the negative electrode active material” in the present application means that the negative electrode sheet does not contain the negative electrode active material layer.
  • FIG. 1 shows a schematic cross-sectional structure diagram of an electrochemical device according to some embodiments of the present application.
  • the electrochemical device 100 includes a positive pole piece 10, a negative pole piece 20, and and the separator 30 between the negative electrode sheet 20.
  • the separator 30 is used to separate the positive pole piece 10 and the negative pole piece 20 , prevent the internal short circuit of the electrochemical device 100 , allow electrolyte ions to pass through freely, and complete the electrochemical charging and discharging process.
  • the positive electrode sheet 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on both surfaces in the thickness direction of the positive electrode current collector 11 itself.
  • the positive electrode active material layer 12 includes a positive electrode active material containing lithium.
  • the negative electrode sheet 20 includes a negative electrode current collector 21 and a ceramic coating 40 disposed on both surfaces of the negative electrode current collector 21 in the thickness direction of itself, and also includes two lithium metal layers between the negative electrode current collector 21 and the ceramic coating 40 twenty two.
  • the inorganic powder selected in the ceramic coating exists in the form of particles, and there are gaps between the particles in the ceramic coating, so there will be particle gaps between the ceramic coating and the negative electrode current collector.
  • the lithium metal layer is formed in the interparticle gap in a discontinuous state.
  • the above “lithium metal layer is located between the negative electrode current collector and the ceramic coating” can also be understood as: the discontinuous lithium metal layer is located in the gaps between the particles in the ceramic coating near the negative electrode current collector.
  • the lithium metal layer is elemental lithium, and the thickness of the lithium metal layer is greater than 0 ⁇ m and less than or equal to 100 ⁇ m.
  • the electrochemical device further includes an electrolyte, and the electrolyte includes fluoroethylene carbonate (FEC) and lithium difluorooxalate borate (LiDFOB); based on the quality of the electrolyte, the fluoroethylene carbonate
  • the mass percentage W 1 of the ester is 0.1% to 10%, preferably 0.1% to 6%
  • the mass percentage W 2 of lithium difluorooxalate borate is 0.05% to 5%, preferably 3% to 4%.
  • the mass percentage W of fluoroethylene carbonate can be 0.1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any two of the above Any value within a range of values.
  • the mass percentage W 2 of lithium difluorooxalate borate can be 0.05%, 0.5%, 1%, 2%, 3%, 4%, 5% or any value between any two value ranges mentioned above.
  • the electrolyte in the electrochemical device includes fluoroethylene carbonate and lithium difluorooxalate borate, and the mass percentage content of fluoroethylene carbonate and lithium difluorooxalate borate is regulated within the above range, which is beneficial to the negative electrode A better SEI film is formed on the surface of the pole piece, which is conducive to the uniform deposition of Li + on the negative electrode current collector, forming a dense and uniform lithium metal layer, thereby realizing the reversibility and stability of lithium metal layer plating, and meeting the requirements of electrochemical devices. cycle performance. Therefore, the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the positive electrode active material containing lithium includes at least one of lithium cobaltate (LiCoO 2 ), lithium manganate, lithium nickel cobalt manganate, lithium titanate or lithium fluoride.
  • LiCoO 2 lithium cobaltate
  • the selection of the above-mentioned lithium-containing positive electrode active material is more conducive to the electrochemical device having lower material costs while meeting the energy density and cycle performance, and effectively reducing the production cost of the electrochemical device.
  • the positive electrode active material layer further includes a positive electrode lithium replenishing agent
  • the positive electrode lithium replenishing agent includes at least one of Li 2 O or Li x MO y
  • the positive electrode lithium replenishing agent includes Li 2 O and Li x MO y ; 2 ⁇ x ⁇ 6, 2 ⁇ y ⁇ 4, M includes at least one of Al, Ni, Co, Mg, Mn, Cu, Fe or Ti.
  • the mass percentage W 3 of the positive electrode lithium supplementing agent is 3% to 10%.
  • the mass percentage W of the positive electrode lithium supplement can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value between any two of the above-mentioned numerical ranges .
  • the electrochemical device can further improve the cycle performance of the electrochemical device while reducing the production cost.
  • the positive lithium replenishing agent includes Li 2 O and Li x MO y at the same time, Li x MO y can further catalyze Li 2 O to release more Li + at a lower potential to provide an additional lithium source, so that the electrochemical The device further improves the cycle performance of the electrochemical device while reducing the production cost.
  • the lithium supplementing agent for the positive electrode includes Li 2 O and Li x MO y
  • the mass ratio of Li 2 O and Li x MO y is not particularly limited, as long as the purpose of this application can be achieved.
  • the mass ratio of Li 2 O and Li x MO y is 30:70 to 35:65.
  • the positive electrode active material layer also includes a positive electrode additive
  • the positive electrode additive includes a composite material formed by an inorganic lithium salt and a first conductive agent, and the mass ratio of the inorganic lithium salt to the first conductive agent is 1:3 to 1:7; based on the positive electrode active material layer, the mass percentage W 4 of the positive electrode additive is 4% to 8%.
  • the mass ratio of the inorganic lithium salt to the first conductive agent is 1:3, 1:4, 1:5, 1:6, 1:7 or any ratio between any two ratio ranges mentioned above.
  • the mass percentage W 4 of the positive electrode additive can be 4%, 5%, 6%, 7%, 8%, or any value between any two value ranges mentioned above.
  • the selection of the above-mentioned positive electrode additive, and the mass percentage content W4 of the positive electrode additive in the positive electrode active material layer are regulated in the above-mentioned range, can release more Li in the charge-discharge cycle process of the electrochemical device to provide additional Lithium source, improve the first discharge capacity of the electrochemical device, reduce the charge transfer resistance of the electrochemical device, and improve the energy density, cycle performance and rate performance of the electrochemical device.
  • the irreversible loss of lithium in the initial anode-free electrochemical device can be offset, and the reversibility and stability of the lithium metal layer plating can be realized, thereby improving the cycle performance of the electrochemical device.
  • the energy density, cycle performance and rate performance of the electrochemical device can be further improved while reducing the production cost.
  • the inorganic lithium salt includes Li s Q a N b O t , 2 ⁇ s ⁇ 8, 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, a+b ⁇ 1, 2 ⁇ t ⁇ 6,
  • Q is selected from any of Fe, Co, Mn, Ni, Zr, V, Nb or Mo
  • N is selected from Al, Mg, Ti, Cr, Y, Sr, Si, W, Ga or Zn Any one
  • the first conductive agent includes at least one of graphene, acetylene black, single-walled carbon nanotubes or multi-walled carbon nanotubes.
  • the preparation method of positive electrode additive comprises the following steps:
  • step (2) (2) calcining the precursor of the inorganic lithium salt obtained in step (1) under a protective gas atmosphere, then cooling and ball milling to obtain inorganic lithium salt particles, namely Li s Q a N b O t ;
  • the positive pole piece further includes a ceramic coating, and the ceramic coating is disposed on the surface of the positive active material layer.
  • the surface of the positive electrode active material layer refers to a surface that is not in contact with the positive electrode current collector among the two surfaces of the thickness of the positive electrode active material layer itself.
  • the ceramic coating is arranged on the surface of the positive electrode active material layer, which is more conducive to preventing the lithium dendrites precipitated from the negative electrode sheet from inserting into the positive electrode sheet, thereby improving the safety performance and thermal stability of the electrochemical device.
  • FIG. 2 shows a schematic structural view of the positive electrode sheet in some embodiments of the present application.
  • the positive electrode sheet 10 includes a positive electrode current collector 11, a positive electrode active material layer 12 and a ceramic coating 40, wherein, two positive electrode active material layers 12 are respectively arranged on the two surfaces of the thickness direction of the positive electrode current collector 11 itself, and the two ceramic coatings 40 are independently arranged on the two surfaces of the thickness direction of the positive electrode active material layer 12 itself.
  • the positive electrode active material layer 12 is located between the positive electrode current collector 11 and the ceramic coating 40 .
  • the two positive electrode active material layers 12 can be the same or different, and the two ceramic coatings 40 can be the same or different.
  • in the positive electrode sheet 10 shown in FIG. There are no restrictions, as long as the purpose of this application can be achieved.
  • the ceramic coating includes inorganic powder and a first binder; based on the quality of the ceramic coating, the mass percentage W of the inorganic powder is 85 % to 95%, and the first binder is The mass percent content W 6 of the binder is 5% to 15%.
  • the mass percentage W 5 of the inorganic powder can be 85%, 87%, 89%, 91%, 93%, 95% or any value between any two value ranges mentioned above.
  • the mass percentage W 6 of the first binder may be 5%, 7%, 9%, 11%, 13%, 15%, or any value between any two of the above ranges.
  • the above materials are selected to form the ceramic coating, and the mass percentages of the inorganic powder and the first binder in the ceramic coating are controlled within the above range, which is more conducive to the function of the ceramic coating.
  • the electrochemical device has lower material cost while satisfying the energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the inorganic powder includes at least one of alumina, magnesia, zirconia, or boehmite
  • the first binder includes polyacrylic acid, polyvinylidene fluoride, polyimide, or at least one of polyvinyl alcohol.
  • the coating weight of the ceramic coating is 5 mg/5000 mm 2 to 20 mg/5000 mm 2 .
  • the coating weight of the ceramic coating is 5mg/5000mm 2 , 10mg/5000mm 2 , 15mg/5000mm 2 , 20mg/5000mm 2 or any value between any two of the above ranges. Regulate the coating weight of the ceramic coating within the above range, so that the ceramic coating can be evenly covered on the negative electrode current collector, which is more conducive to improving the uniformity and stability of the lithium metal layer plating, which is more conducive to improving the magnification of the electrochemical device performance and cycle performance. Therefore, the rate performance and cycle performance of the electrochemical device can be further improved while reducing the production cost.
  • the ceramic coating has a thickness of 1 ⁇ m to 3 ⁇ m.
  • the thickness of the ceramic coating can be 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m or any value between any two of the above ranges.
  • the thickness of the ceramic coating is too small (for example, less than 1 ⁇ m), the mechanical strength of the ceramic coating is not enough, and the purpose of this application cannot be achieved; the thickness of the ceramic coating is too large (for example, greater than 3 ⁇ m), the volume of the electrochemical device is increased accordingly Large, will affect the energy density of the electrochemical device. Regulating the thickness of the ceramic coating within the above range enables the role of the ceramic coating in this application to be effectively brought into play. Therefore, the electrochemical device has lower material production cost under the condition of satisfying energy density and cycle performance, so that the production cost of the electrochemical device is effectively reduced.
  • the negative electrode sheet further includes a conductive layer, the conductive layer is disposed between the negative electrode current collector and the ceramic coating, and the lithium metal layer is disposed between the negative electrode current collector and the conductive layer.
  • the setting of the conductive layer can receive the Li + released from the positive pole piece, inhibit the formation of lithium precipitation and dead lithium, thereby improving the safety performance and cycle performance of the electrochemical device.
  • FIG. 3 shows a schematic structural view of the negative electrode sheet in some embodiments of the present application.
  • the negative electrode current collector 21 includes a first surface 21a and a second surface 21b oppositely arranged in the direction of its own thickness.
  • a lithium metal layer 22 is independently disposed on the first surface 21 a and the second surface 21 b.
  • the conductive layer 23 is disposed between the negative electrode current collector 21 and the ceramic coating 40
  • the lithium metal layer 22 is disposed between the negative electrode current collector 21 and the conductive layer 23 .
  • the lithium metal layer 22, the conductive layer 23 and the ceramic coating 40 are sequentially arranged on the first surface 21a; along the direction away from the second surface 21b, on the second surface 21b
  • the lithium metal layer 22 , the conductive layer 23 and the ceramic coating 40 are sequentially provided.
  • the two conductive layers 23 may be the same or different, and the two ceramic coating layers 40 may be the same or different.
  • the conductive layer includes a second conductive agent and a second binder; based on the mass of the conductive layer, the mass percentage W 7 of the second conductive agent is 60% to 70%, and the second binder The mass percent content W8 of the binding agent is 30% to 40%.
  • the mass percentage W 7 of the second conductive agent may be 60%, 62%, 64%, 66%, 68%, 70%, or any value between any two value ranges mentioned above.
  • the mass percentage W 8 of the second binder may be 30%, 32%, 34%, 36%, 38%, 40%, or any value between any two value ranges mentioned above.
  • the above-mentioned materials are selected to form the conductive layer, and the mass percentages of the second conductive agent and the second binder are controlled within the above-mentioned range, which is more conducive to the function of the conductive layer.
  • the conductive layer can receive the Li + released from the positive pole piece, inhibit lithium precipitation and the formation of dead lithium, thereby improving the safety performance and cycle performance of the electrochemical device.
  • the second conductive agent includes at least one of amorphous carbon, single-walled carbon nanotubes, or multi-walled carbon nanotubes;
  • the second binder includes styrene-butadiene rubber, carboxymethyl cellulose or at least one of polyvinyl alcohol.
  • the conductive layer has a thickness of 0.5 ⁇ m to 3 ⁇ m.
  • the thickness of the conductive layer may be 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m or any value between any two ranges of values mentioned above. If the conductive thickness is too small (such as less than 0.5 ⁇ m), the mechanical strength of the conductive layer is not enough to achieve the purpose of this application; if the thickness of the conductive layer is too large (such as greater than 3 ⁇ m), the volume of the electrochemical device will increase accordingly. Affects the energy density of electrochemical devices. Regulating the thickness of the conductive layer within the above range enables the conductive layer to effectively play its role in this application. Therefore, the electrochemical device has better safety performance and cycle performance under the condition of lower material cost.
  • the present application has no special limitation on the positive electrode current collector, as long as the purpose of the present application can be achieved.
  • the positive current collector may include aluminum foil, aluminum alloy foil, or a composite current collector.
  • the thickness of the positive electrode current collector and the positive electrode active material layer there is no particular limitation on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the positive electrode collector is 5 ⁇ m to 20 ⁇ m, preferably 6 ⁇ m to 18 ⁇ m.
  • the thickness of the positive electrode active material layer on one side is 30 ⁇ m to 120 ⁇ m.
  • the present application has no particular limitation on the negative electrode collector, as long as the purpose of the present application can be achieved.
  • the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a composite current collector.
  • the thickness of the negative electrode current collector is 6 ⁇ m to 10 ⁇ m.
  • the electrolytic solution of the present application also includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ), tetra Lithium phenylboron (LiB(C 6 H 5 ) 4 ), lithium methanesulfonate (LiCH 3 SO 3 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium bistrifluoromethanesulfonylimide (LiN At least one of (SO 2 CF 3 ) 2 ), LiC(SO 2 CF 3 ) 3 , lithium hexafluorosilicate (LiSiF 6 ), lithium bisoxalate borate (LiBOB) or lithium difluoroborate (LiF 2 OB) .
  • LiPF 6 lithium hexafluorophosphate
  • the non-aqueous solvent may be at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • the above-mentioned carbonate compound may be at least one of chain carbonate compound, cyclic carbonate compound or fluorocarbonate compound.
  • Examples of the above-mentioned chain carbonate compound are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylenepropyl carbonate (EPC) or carbonic acid At least one of ethyl methyl ester (EMC).
  • cyclic carbonate compound is at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or vinylethylene carbonate (VEC).
  • fluorocarbonate compounds are 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, At least one of 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate.
  • Examples of the above carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , at least one of decanolactone, valerolactone, mevalonolactone or caprolactone.
  • Examples of the aforementioned ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl At least one of oxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • Examples of the aforementioned other organic solvents are propyl propionate, dimethylsulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl - at least one of 2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.
  • the total content of the above non-aqueous solvents is 5% to 90%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% , 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or any range therebetween.
  • the electrochemical device of the present application also includes a separator, and the present application has no particular limitation on the separator, as long as the purpose of the present application can be achieved.
  • 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 battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery, and the like.
  • 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 pole piece, separator and negative pole piece in order, and place the It is wound to obtain an electrode assembly with a winding structure, the electrode assembly is put into the packaging case, the electrolyte is injected into the packaging case and sealed to obtain an electrochemical device; or, the positive pole piece, the separator and the negative pole piece are stacked in order, Then use adhesive tape to fix the four corners of the entire laminated structure to obtain the electrode assembly of the laminated structure, put the electrode assembly into the packaging case, inject the electrolyte into the packaging case and seal it, and obtain the electrochemical device.
  • anti-overcurrent elements, guide plates, etc. can also be placed in the packaging case as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • a second aspect of the present application provides an electronic device, which includes the electrochemical device described in any one of the foregoing embodiments. Therefore, the production cost of the electronic device is also reduced.
  • the electronic devices of the present application are not particularly limited, and may include but not limited to the following types: notebook computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-mounted Stereo headphones, VCRs, LCD TVs, portable cleaners, portable CD players, mini-discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, electric motors, automobiles, motorcycles, power-assisted bicycles , bicycles, lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras and large household batteries, etc.
  • the material cost of a single lithium-ion battery is the sum of the material costs of each component.
  • Each component material is four main materials and auxiliary materials, among which, the four main materials are positive electrode active material, negative electrode active material, separator, electrolyte, and auxiliary materials are negative electrode current collector, positive electrode current collector, conductive agent, adhesive Agents, solvents, gummed paper, tab coils, packaging shells, etc.
  • Material cost of each component unit price ⁇ unit usage.
  • Proportion of material cost (%) material cost of the lithium-ion battery in each embodiment/material cost of the lithium-ion battery in Comparative Example 1 ⁇ 100%.
  • the test temperature is 25°C, the lithium-ion battery is fully charged first, and then discharged to 3.0V at a constant current of 0.2C, which is the discharge capacity.
  • the lithium-ion battery is tested for cycle capacity retention: the test temperature is 25°C, charge to the rated voltage at a constant current of 0.2C, charge at a constant voltage to 0.025C, and discharge to 3.0V at 0.2C after standing for 5 minutes.
  • the capacity obtained in this step is the initial capacity, and the 0.2C charge/0.2C discharge cycle test is performed, and the capacity after each cycle is compared with the initial capacity to obtain a capacity decay curve, and the capacity retention rate is directly obtained from the capacity decay curve.
  • the lithium-containing positive electrode active material LiCoO 2 , the conductive agent conductive carbon, and the positive electrode binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 95.8:2.0:2.2, and then N-methylpyrrolidone (NMP) was added as a solvent.
  • NMP N-methylpyrrolidone
  • the ceramic coating slurry was prepared by mixing the inorganic powder alumina and the first binder polyacrylic acid at a mass ratio of 90:10.
  • the ceramic coating slurry is evenly coated on one surface of a copper foil with a thickness of 6 ⁇ m, and dried at 110° C. to obtain a negative electrode sheet with a ceramic coating thickness of 3 ⁇ m on one side of the ceramic coating, and then in the The above coating steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet coated with a ceramic coating on both sides.
  • the negative electrode sheet was cold-pressed and cut into sheets with a specification of 76 mm ⁇ 851 mm for use. Among them, the coating weight of the ceramic coating is 18.5mg/5000mm 2 .
  • the organic solvents EC, EMC and DEC In a dry argon atmosphere, mix the organic solvents EC, EMC and DEC according to the mass ratio of 30:50:20, then add LiPF 6 to the organic solvent to dissolve and mix well to obtain a base solution, and then add FEC and DEC to the base solution LiDFOB.
  • the molar concentration of LiPF 6 in the electrolyte is 1.15mol/L; based on the mass of the electrolyte, the mass percentage W 1 of FEC is 1%, and the mass percentage W 2 of LiDFOB is 0.6%.
  • the positive electrode sheet, separator, and negative electrode sheet prepared above in sequence so that the separator is in the middle of the positive and negative electrodes for isolation, and wind up to obtain an electrode assembly .
  • the electrode assembly is placed in the packaging case, the prepared electrolyte is injected and packaged, and the lithium-ion battery is obtained through processes such as formation, degassing, and edge trimming.
  • the formation process is as follows: the formation charging current is 0.1C, the formation temperature is 85°C, and the formation resting time is 180 seconds.
  • the mass percentage of the positive electrode active material is reduced to 92.8%, and the rest are the same as in Examples 1-9. same.
  • Example 2-1 Except for adjusting relevant preparation parameters according to Table 2, the rest are the same as in Example 2-1.
  • positive electrode active material In addition to adding the positive electrode additive (the mass ratio of inorganic lithium salt Li 5 FeO 4 and the first conductive agent graphene is 1:5) with mass percent W 4 being 6% in ⁇ preparation of positive electrode sheet>, positive electrode active material The mass percent composition of the reduction is outside 89.8%, and all the other are identical with embodiment 1-9.
  • the ceramic coating slurry was prepared by mixing the inorganic powder alumina and the first binder polyacrylic acid in a mass ratio of 90:10.
  • the conductive layer slurry was prepared by mixing the second conductive agent, amorphous carbon, and the second binder, styrene-butadiene rubber, at a mass ratio of 65:35.
  • the conductive layer slurry and the ceramic coating slurry were uniformly coated on one surface of a copper foil with a thickness of 6 ⁇ m in sequence, and dried at 110° C. to obtain a single sheet with a conductive layer thickness of 1.5 ⁇ m and a ceramic coating thickness of 2 ⁇ m.
  • the negative electrode sheet was cold-pressed and cut into sheets with a specification of 76 mm ⁇ 851 mm for use.
  • the coating weight of the conductive layer is 0.5 mg/5000 mm 2
  • the coating weight of the ceramic coating is 13.6 mg/5000 mm 2 .
  • the negative electrode active material graphite the conductive agent conductive carbon black, and the binder styrene-butadiene rubber (SBR) at a mass ratio of 85:5:10, then add deionized water as a solvent, and prepare a negative electrode slurry with a solid content of 70wt%. and stir evenly, uniformly coat the negative electrode slurry on one surface of a copper foil with a thickness of 6 ⁇ m, and dry it at 110° C. to obtain a negative electrode active material layer with a thickness of 130 ⁇ m.
  • Negative electrode sheet and then repeat the above coating steps on the other surface of the negative electrode sheet to obtain a negative electrode sheet coated with a negative electrode active material layer on both sides.
  • the negative electrode sheet was cold-pressed and cut into sheets with a specification of 76 mm ⁇ 851 mm for use.
  • Example 1-21 From Example 1-1 to Example 1-9, Example 1-21, and Comparative Example 1, it can be seen that when the negative electrode sheet of a lithium ion battery does not contain a negative active material, the application is provided on the surface of the negative electrode current collector.
  • the ceramic coating within the range and the electrolyte contains FEC and LiDFOB within the mass percentage range of the application, the lithium-ion battery has a good initial discharge capacity and can meet the needs of a small amount of charge-discharge cycle products. Material cost is reduced.
  • the type of inorganic powder and first binder in the ceramic coating usually also affects the material cost, initial discharge capacity and capacity retention of lithium-ion batteries.
  • the lithium-ion battery whose type of inorganic powder and first binder is within the scope of the application is selected, it has a good initial discharge capacity and can meet the requirements of the present invention. In the case of a small amount of charge-discharge cycle product demand, the cost of materials is reduced.
  • the mass percentage of the inorganic powder and the first binder in the ceramic coating usually also affects the material cost, initial discharge capacity and capacity retention rate of the lithium-ion battery. As can be seen from Examples 1-9, Examples 1-15 and Examples 1-16, the lithium-ion battery with the mass percentage of the inorganic powder and the first binder within the scope of the application is selected. Good first-time discharge capacity and the ability to meet the demand for a small amount of charge-discharge cycle products reduce material costs.
  • the coating weight of the ceramic coating also typically affects the bill of material cost, first discharge capacity, and capacity retention of Li-ion batteries. Can find out from embodiment 1-9, embodiment 1-17 and embodiment 1-18, select the coating weight of ceramic coating for use in the lithium ion battery within the scope of the application, it has good discharge capacity for the first time, and In the case of being able to meet the demand for a small amount of charge-discharge cycle products, the cost of materials is reduced.
  • the thickness of the ceramic coating also typically affects the bill of material cost, first discharge capacity, and capacity retention of Li-ion batteries. Can find out from embodiment 1-9, embodiment 1-19 and embodiment 1-20, select the thickness of ceramic coating for use in the lithium ion battery within the scope of the application, it has good discharge capacity for the first time and can satisfy In the case of a small amount of charge-discharge cycle product demand, the cost of materials is reduced.
  • the type of positive lithium-supplementing agent and the mass percentage of the positive-electrode lithium-supplementing agent in the positive-electrode active material layer usually also affect the material cost, initial discharge capacity and capacity retention of the lithium-ion battery. From Examples 1-9, Example 2-1 to Example 2-7, it can be seen that the lithium ion battery with the type and mass percentage content of the positive electrode lithium supplement within the scope of the application has a good initial performance. When the discharge capacity and the demand for a small amount of charge-discharge cycle products can be met, the cost of materials is reduced.
  • the type of positive electrode additive and its mass percentage in the positive electrode active material layer, the mass ratio of inorganic lithium salt and the first conductive agent usually also affect the material cost, initial discharge capacity and capacity retention of lithium-ion batteries. From Examples 1-9, Example 3-1 to Example 3-8, it can be seen that the type of positive electrode additive and its mass percentage in the positive electrode active material layer, the content of the inorganic lithium salt and the first conductive agent are selected.
  • the lithium-ion battery with a mass ratio within the range of the present application has a good initial discharge capacity and can meet the demand for a small amount of charge-discharge cycle products, thereby reducing the cost of materials.
  • the setting of the ceramic coating in the positive electrode sheet usually also affects the material cost, initial discharge capacity and capacity retention of lithium-ion batteries. From Example 3-2 and Example 3-9, it can be seen that the lithium-ion battery with a ceramic coating in the positive pole piece is selected, which has good initial discharge capacity and can meet the needs of a small amount of charge-discharge cycle products. In this case, the material cost is reduced.
  • the arrangement of the conductive layer in the negative electrode sheet usually also affects the material cost, initial discharge capacity and capacity retention of lithium-ion batteries. Can find out from embodiment 3-2 and embodiment 4-1, embodiment 3-9 and embodiment 4-2, select the lithium ion battery that is provided with conductive layer in the negative pole sheet for selection, it has good discharge capacity for the first time , and can meet the demand for a small amount of charge-discharge cycle products, reducing the cost of materials.
  • the mass percentage content of the second conductive layer and the second binder in the conductive layer will generally also affect the material cost, initial discharge capacity and capacity retention rate of the lithium-ion battery. From Example 4-2 to Example 4-4, it can be seen that the lithium-ion battery whose mass percentage content of the second conductive layer and the second binder in the conductive layer is within the scope of the application is selected, it has a good In the case of the first discharge capacity and the ability to meet the demand for a small amount of charge-discharge cycle products, the cost of materials is reduced.

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Abstract

本申请提供了一种电化学装置及包含电化学装置的电子装置，其中，电化学装置通过在负极极片不设置负极活性材料，而是在负极集流体自身厚度方向的两个表面上设置陶瓷涂层，陶瓷涂层在电化学装置的充电过程中，能够促进Li +在负极集流体上的均匀沉积形成锂金属层，使锂金属层形成于负极集流体与陶瓷涂层之间，锂金属层均匀且致密，同时陶瓷涂层也能够吸收锂枝晶。这样，原本设置负极活性材料所占用的厚度空间被省去，所节省出来的厚度空间可以通过在正极极片上增加低价的正极活性材料来满足电化学装置的能量密度。并且，陶瓷涂层的成本低于负极活性材料层的成本。由此，电化学装置的生产成本得到有效降低。

Description

电化学装置及包含该电化学装置的电子装置 技术领域
本申请涉及电化学技术领域，具体涉及一种电化学装置及包含该电化学装置的电子装置。
背景技术
二次电池(例如锂离子电池)作为一种新型的可移动储能装置，具有储能密度大、开路电压高、自放电率低、循环寿命长、安全性能好等优点，在手机、笔记本电脑、摄像机等便携式小型电子设备领域，以及大型电动运输工作和可再生能源存储领域的需求越来越大。但是，如一次性电子烟类的仅需少量充放电循环的电子产品，对二次电池的循环寿命要求较低，因此，如何通过降低此类二次电池的生产成本来获得市场竞争力成为本领域技术人员亟待解决的技术问题。
发明内容
本申请提供了一种电化学装置及包含该电化学装置的电子装置，以降低电化学装置的生产成本。
需要说明的是，本申请的发明内容中，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。
本申请第一方面提供一种电化学装置，包括正极极片和负极极片；所述正极极片包括正极集流体以及设置于所述正极集流体至少一个表面上的正极活性材料层，所述正极活性材料层包括含锂的正极活性材料；所述负极极片包括负极集流体以及设置于所述负极集流体两个表面上的陶瓷涂层，所述负极极片还包括所述含锂的正极活性材料中的锂离子在充电过程中在所述负极集流体的表面沉积形成的锂金属层，所述锂金属层位于所述负极集流体与所述陶瓷涂层之间；所述负极极片不包含负极活性材料。
本申请人经大量研究发现，负极极片不设置负极活性材料，而是在负极集流体自身厚度方向的两个表面设置陶瓷涂层，陶瓷涂层在电化学装置的充电过程中，能够促进Li离子(Li +)在负极集流体上的均匀沉积形成锂金属层，使锂金属层形成于负极集流体与陶瓷涂层之间，且锂金属层均匀且致密，同时陶瓷涂层也能够吸收锂枝晶。这样，原本设置负极活性材料所占用的厚度空间被省去，所节省出来的厚度空间可以通过在正极极片上增加低价的正极活性材料来满足电化学装置的能量密度。并且，陶瓷涂层的成本低于负极活性材 料层的成本。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，电化学装置还包括电解液，所述电解液包括氟代碳酸亚乙酯和二氟草酸硼酸锂；基于所述电解液的质量，所述氟代碳酸亚乙酯的质量百分含量W 1为0.1％至10％，所述二氟草酸硼酸锂的质量百分含量W 2为0.05％至5％。电化学装置中的电解液包括氟代碳酸亚乙酯和二氟草酸硼酸锂，且将氟代碳酸亚乙酯和二氟草酸硼酸锂的质量百分含量调控在上述范围内，有利于在负极极片表面形成更好的固态电解质界面(SEI)膜，有利于Li +在负极集流体上的均匀沉积，形成致密且均匀的锂金属层，从而实现锂金属层电镀的可逆性和稳定性，满足电化学装置的循环性能。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，所述含锂的正极活性材料包括钴酸锂、锰酸锂、镍钴锰酸锂、钛酸锂或氟酸锂中的至少一种。选用上述种类的含锂的正极活性材料，更利于电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，所述正极活性材料层还包括正极补锂剂，所述正极补锂剂包括Li 2O或Li xMO y中的至少一种，2≤x≤6，2≤y≤4，M包括Al、Ni、Co、Mg、Mn、Cu、Fe或Ti中的至少一种；基于所述正极活性材料层的质量，所述正极补锂剂的质量百分含量W 3为3％至10％。选用上述种类的正极补锂剂，以及调控正极活性材料层中正极补锂剂的质量百分含量W 3在上述范围内，使Li 2O在较低电位下释放更多的Li +以提供额外的锂源，使电化学装置在长期循环过程中，可以抵消锂在初始无负极活性材料的电化学装置中的不可逆损耗，实现锂金属层电镀的可逆性和稳定性，从而提升电化学装置的循环性能。由此，电化学装置在降低生产成本的情况下，能进一步提升电化学装置的循环性能。
在本申请的一些实施例中，所述正极活性材料层还包括正极添加剂，所述正极添加剂包括无机锂盐和第一导电剂形成的复合材料，所述无机锂盐与所述第一导电剂的质量比为1:3至1:7；基于所述正极活性材料层，所述正极添加剂的质量百分含量W 4为4％至8％。上述正极添加剂的选用，以及将正极活性材料层中正极添加剂的质量百分含量W 4调控在上述范围内，能够在电化学装置的充放电循环过程中，释放更多的Li +以提供额外的锂源，提高电化学装置的首次放电容量，降低电化学装置的电荷转移阻抗，提高电化学装置的能 量密度、循环性能及倍率性能。这样，在电化学装置的长期循环过程中，可以抵消锂在初始无负极电化学装置中的不可逆损耗，实现锂金属层电镀的可逆性和稳定性，从而提升电化学装置的循环性能。由此，电化学装置在降低生产成本的情况下，其能量密度、循环性能及倍率性得以进一步提升。
在本申请的一些实施例中，所述无机锂盐包括Li sQ aN bO t，2≤s≤8，0≤a≤1，0≤b≤1，a+b≥1，2≤t≤6，Q选自Fe、Co、Mn、Ni、Zr、V、Nb或Mo中的任一种，N选自Al、Mg、Ti、Cr、Y、Sr、Si、W、Ga或Zn中的任一种；所述第一导电剂包括石墨烯、乙炔黑、单壁碳纳米管或多壁碳纳米管中的至少一种。上述无机锂盐和第一导电剂的选用，更利于使电化学装置在降低生产成本的情况下，进一步提升其循环性能。
在本申请的一些实施例中，所述正极极片还包括所述陶瓷涂层，所述陶瓷涂层设置于所述正极活性材料层的表面。将陶瓷涂层设置于正极活性材料层的表面，更利于阻挡负极极片析出的锂枝晶插入正极极片中，从而提升电化学装置的安全性能和热稳定性。
在本申请的一些实施例中，所述陶瓷涂层包括无机粉体和第一粘结剂；基于所述陶瓷涂层的质量，所述无机粉体的质量百分含量W 5为85％至95％，所述第一粘结剂的质量百分含量W 6为5％至15％。选用上述材料形成陶瓷涂层，且将无机粉体和第一粘结剂在陶瓷涂层中的质量百分含量调控在上述范围内，更利于陶瓷涂层的作用的发挥。这样，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，所述无机粉体包括氧化铝、氧化镁、氧化锆或勃姆石中的至少一种，所述第一粘结剂包括聚丙烯酸、聚偏氟乙烯、聚酰亚胺或聚乙烯醇中的至少一种。上述材料的选用，更利于陶瓷涂层的形成及其作用的发挥。这样，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。在本申请的一些实施例中，所述陶瓷涂层的涂布重量为5mg/5000mm 2至20mg/5000mm 2。将陶瓷涂层的涂布重量调控在上述范围内，更利于提升电化学装置的倍率性能和循环性能。从而使电化学装置在降低生产成本的情况下，进一步提升电化学装置的倍率性能和循环性能。
在本申请的一些实施例中，所述陶瓷涂层的厚度为1μm至3μm。将陶瓷涂层的厚度调控在上述范围内，使陶瓷涂层在本申请中的作用得以有效发挥。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料生产成本，使电化学装置的生产成本得到 有效降低。
在本申请的一些实施例中，所述负极极片还包括导电层，所述导电层设置于所述负极集流体与所述陶瓷涂层之间，所述锂金属层设置在所述负极集流体与所述导电层之间。导电层的设置，能够接收正极极片脱出的Li +，抑制析锂及死锂的形成，从而提升电化学装置的安全性能和循环性能。
在本申请的一些实施例中，所述导电层包括第二导电剂和第二粘结剂；基于所述导电层的质量，所述第二导电剂的质量百分含量W 7为60％至70％，所述第二粘结剂的质量百分含量W 8为30％至40％。
在本申请的一些实施例中，所述第二导电剂包括无定型碳、单壁碳纳米管或多壁碳纳米管中的至少一种；所述第二粘结剂包括丁苯橡胶、羧甲基纤维素或聚乙烯醇中的至少一种。
选用上述材料形成导电层，且将第二导电剂和第二粘结剂的质量百分含量调控在上述范围内，更利于导电层的作用的发挥。这样，导电层能够接收正极极片脱出的Li +，抑制析锂及死锂的形成，从而提升电化学装置的安全性能和循环性能。
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所述的电化学装置。
本申请的有益效果：
本申请实施例通过在负极极片不设置负极活性材料，而是在负极集流体自身厚度方向的两个表面上设置陶瓷涂层，陶瓷涂层在电化学装置的充电过程中，能够促进Li +在负极集流体上的均匀沉积形成锂金属层，使锂金属层形成于负极集流体与陶瓷涂层之间，锂金属层均匀且致密，同时陶瓷涂层也能够吸收锂枝晶。这样，原本设置负极活性材料所占用的厚度空间被省去，所节省出来的厚度空间可以通过在正极极片上增加低价的正极活性材料来满足电化学装置的能量密度。并且，陶瓷涂层的成本低于负极活性材料层的成本。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面对实施例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申请的一些实施例，本领域普通技术人员来讲还可以根据这些附图获得其他的附图。
图1为本申请一些实施例的电化学装置的剖面结构示意图；
图2为本申请一些实施例中的正极极片的剖面结构示意图；
图3为本申请一些实施例中的负极极片的剖面结构示意图。
附图标记的说明：
10正极极片；11正极集流体；12正极活性材料层；20负极极片；21负极集流体；22锂金属层；23导电层；40陶瓷涂层；30隔膜；100电化学装置。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。本领域普通技术人员基于本申请中的实施例所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，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。
本申请第一方面提供一种电化学装置，包括正极极片和负极极片；正极极片包括正极集流体以及设置于正极集流体至少一个表面上的正极活性材料层，正极活性材料层包括含锂的正极活性材料；负极极片包括负极集流体以及设置于负极集流体两个表面上的陶瓷涂层，负极极片还包括含锂的正极活性材料中的锂离子在充电过程中在负极集流体的表面沉积形成的锂金属层，锂金属层位于负极集流体与陶瓷涂层之间；负极极片不包含负极活性材料。
本申请人经大量研究发现，负极极片不设置负极活性材料，而是在负极集流体自身厚度方向的两个表面设置陶瓷涂层，陶瓷涂层在电化学装置的充电过程中，能够促进Li +在负极集流体上的均匀沉积形成锂金属层，使锂金属层形成于负极集流体与陶瓷涂层之间，锂金属层均匀且致密，同时陶瓷涂层也能够吸收锂枝晶。这样，原本设置负极活性材料所占用的厚度空间被省去(现有技术中，含有负极活性材料的负极活性材料层厚度通常大于100μm)，所节省出来的厚度空间可以通过在正极极片上增加低价的正极活性材料来满足电化学装置的能量密度。并且，陶瓷涂层的成本低于负极活性材料层的成本。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请中，正极集流体在厚度方向上包括两个相对的第一表面和第二表面，上述“设 置于正极集流体至少一个表面上的正极活性材料层”，本领域技术人员应当理解，正极活性材料层可以设置在第一表面上，也可以设置在第二表面上，还可以同时设置在第一表面和第二表面上，本领域技术人员根据实际需要进行选择即可。需要说明，上述的“表面”可以是第一表面和/或第二表面的全部区域，也可以是第一表面和/或第二表面的部分区域，本申请没有特别限制，只要能实现本申请目的即可。应当理解，本申请的“负极极片不包含负极活性材料”是指负极极片不包含负极活性材料层。
示例性地，图1示出了本申请一些实施例的电化学装置的剖面结构示意图，如图1所示，电化学装置100包括正极极片10、负极极片20以及设置于正极极片10和负极极片20之间的隔膜30。隔膜30的设置用以分隔正极极片10和负极极片20，防止电化学装置100内部短路，允许电解质离子自由通过，完成电化学充放电过程的作用。正极极片10包括正极集流体11以及设置于正极集流体11自身厚度方向的两个表面上的正极活性材料层12，正极活性材料层12包括含锂的正极活性材料。含锂的正极活性材料中的Li +在电化学装置100充电过程中在负极集流体21的表面沉积形成锂金属层22。负极极片20包括负极集流体21以及设置于负极集流体21自身厚度方向的两个表面上的陶瓷涂层40，还包括位于负极集流体21和陶瓷涂层40之间的两层锂金属层22。
需要说明的是，在本申请中，陶瓷涂层中选用的无机粉体以颗粒状存在，陶瓷涂层中的各颗粒间存在间隙，因此陶瓷涂层和负极集流体之间会产生颗粒间隙，锂金属层则以不连续状态形成于颗粒间隙中。上述“锂金属层位于负极集流体与陶瓷涂层之间”也可以理解为：不连续的锂金属层位于靠近负极集流体附近的陶瓷涂层中的各颗粒间隙中。其中，锂金属层为单质锂，锂金属层的厚度大于0μm且小于等于100μm。
在本申请的一些实施例中，电化学装置还包括电解液，电解液包括氟代碳酸亚乙酯(FEC)和二氟草酸硼酸锂(LiDFOB)；基于电解液的质量，氟代碳酸亚乙酯的质量百分含量W 1为0.1％至10％，优选为0.1％至6％，二氟草酸硼酸锂的质量百分含量W 2为0.05％至5％，优选为3％至4％。例如，氟代碳酸亚乙酯的质量百分含量W 1可以为0.1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或上述任两个数值范围间的任一数值。二氟草酸硼酸锂的质量百分含量W 2可以为0.05％、0.5％、1％、2％、3％、4％、5％或上述任两个数值范围间的任一数值。电化学装置中的电解液包括氟代碳酸亚乙酯和二氟草酸硼酸锂，且将氟代碳酸亚乙酯和二氟草酸硼酸锂的质量百分含量调控在上述范围内，有利于在负极极片表面形成更好的SEI膜，有利于Li +在负极集流体上的均匀沉积，形成致密且均匀的锂 金属层，从而实现锂金属层电镀的可逆性和稳定性，满足电化学装置的循环性能。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，含锂的正极活性材料包括钴酸锂(LiCoO 2)、锰酸锂、镍钴锰酸锂、钛酸锂或氟酸锂中的至少一种。选用上述种类的含锂的正极活性材料，更利于电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，正极活性材料层还包括正极补锂剂，正极补锂剂包括Li 2O或Li xMO y中的至少一种，优选地，正极补锂剂包括Li 2O和Li xMO y；2≤x≤6，2≤y≤4，M包括Al、Ni、Co、Mg、Mn、Cu、Fe或Ti中的至少一种。基于正极活性材料层的质量，正极补锂剂的质量百分含量W 3为3％至10％。例如，正极补锂剂的质量百分含量W 3可以为3％、4％、5％、6％、7％、8％、9％、10％或上述任两个数值范围间的任一数值。选用上述种类的正极补锂剂，以及调控正极活性材料层中正极补锂剂的质量百分含量W 3在上述范围内，使Li 2O在较低电位下释放更多的Li +以提供额外的锂源，使电化学装置在长期循环过程中，可以抵消锂在初始无负极活性材料的电化学装置中的不可逆损耗，实现锂金属层电镀的可逆性和稳定性，从而提升电化学装置的循环性能。由此，电化学装置在降低生产成本的情况下，能进一步提升电化学装置的循环性能。当正极补锂剂同时包括Li 2O和Li xMO y，Li xMO y能够更进一步地催化Li 2O在较低电位下释放更多的Li +以提供额外的锂源，从而使电化学装置在降低生产成本的情况下，更进一步地提升电化学装置的循环性能。
进一步地，正极补锂剂包括Li 2O和Li xMO y时，Li 2O和Li xMO y的质量比没有特别限制，只要能够实现本申请目的即可。优选地，Li 2O和Li xMO y的质量比为30:70至35:65。
在本申请的一些实施例中，正极活性材料层还包括正极添加剂，正极添加剂包括无机锂盐和第一导电剂形成的复合材料，无机锂盐与第一导电剂的质量比为1:3至1:7；基于正极活性材料层，正极添加剂的质量百分含量W 4为4％至8％。例如，无机锂盐与第一导电剂的质量比为1:3、1:4、1:5、1:6、1:7或上述任两个比值范围间的任一比值。正极添加剂的质量百分含量W 4可以为4％、5％、6％、7％、8％或上述任两个数值范围间的任一数值。上述正极添加剂的选用，以及将正极活性材料层中正极添加剂的质量百分含量W 4调控在上述范围内，能够在电化学装置的充放电循环过程中，释放更多的Li +以提供额外的锂源，提高电化学装置的首次放电容量，降低电化学装置的电荷转移阻抗，提高电化学装置的能 量密度、循环性能及倍率性能。这样，在电化学装置的长期循环过程中，可以抵消锂在初始无负极电化学装置中的不可逆损耗，实现锂金属层电镀的可逆性和稳定性，从而提升电化学装置的循环性能。由此，电化学装置在降低生产成本的情况下，其能量密度、循环性能及倍率性能得以进一步提升。
在本申请的一些实施例中，无机锂盐包括Li sQ aN bO t，2≤s≤8，0≤a≤1，0≤b≤1，a+b≥1，2≤t≤6，Q选自Fe、Co、Mn、Ni、Zr、V、Nb或Mo中的任一种，N选自Al、Mg、Ti、Cr、Y、Sr、Si、W、Ga或Zn中的任一种；第一导电剂包括石墨烯、乙炔黑、单壁碳纳米管或多壁碳纳米管中的至少一种。上述无机锂盐和第一导电剂的选用，更利于使电化学装置在降低生产成本的情况下，进一步提升其循环性能。
本申请对正极添加剂的制备方法没有特别限制，只要能够实现本申请目的即可。例如，正极添加剂的制备方法包括以下步骤：
(1)将含锂化合物、含有Q元素、含有N元素的化合物按照Li、Q、N的摩尔比为s:a:b溶解于溶剂，搅拌得到均一混合溶液，之后蒸发溶剂、干燥，获得无机锂盐的前驱体；其中，2≤s≤8，0≤a≤1，0≤b≤1，a+b≥1，2≤t≤6，Q选自Fe、Co、Mn、Ni、Zr、V、Nb或Mo中的任一种，N选自Al、Mg、Ti、Cr、Y、Sr、Si、W、Ga或Zn中的任一种；
(2)将步骤(1)中获得的无机锂盐的前驱体在保护气体气氛下煅烧，之后冷却、球磨得到无机锂盐颗粒，即Li sQ aN bO t；
(3)将无机锂盐颗粒超声分散于含有第一导电剂的溶液中，蒸发溶剂、干燥，获得无机锂盐与导电剂形成的复合材料，即正极添加剂；其中，无机锂盐与第一导电剂的质量比为1:3至1:7。
在本申请的一些实施例中，正极极片还包括陶瓷涂层，陶瓷涂层设置于正极活性材料层的表面。需要说明，正极活性材料层的表面是指正极活性材料层自身厚度的两个表面中不与正极集流体接触的一个表面。将陶瓷涂层设置于正极活性材料层的表面，更利于阻挡负极极片析出的锂枝晶插入正极极片中，从而提升电化学装置的安全性能和热稳定性。
示例性地，图2示出了本申请一些实施例中的正极极片的结构示意图，如图2所示，正极极片10包括正极集流体11、正极活性材料层12和陶瓷涂层40，其中，两个正极活性材料层12分别设置于正极集流体11自身厚度方向的两个表面上，两个陶瓷涂层40各自独立地设置于正极活性材料层12自身厚度方向的两个表面中不与正极集流体11接触的一个表面上，使正极活性材料层12位于正极集流体11和陶瓷涂层40之间。其中，两个正极活 性材料层12可以相同或不同，两个陶瓷涂层40可以相同或不同。在本申请的另一些实施例中，如图2所示的正极极片10中，也可以只在两个正极活性材料层12中的任一个表面上设置陶瓷涂层40，本申请对此不做限制，只要能够实现本申请目的即可。
在本申请的一些实施例中，陶瓷涂层包括无机粉体和第一粘结剂；基于陶瓷涂层的质量，无机粉体的质量百分含量W 5为85％至95％，第一粘结剂的质量百分含量W 6为5％至15％。例如，无机粉体的质量百分含量W 5可以为85％、87％、89％、91％、93％、95％或上述任两个数值范围间的任一数值。例如，第一粘结剂的质量百分含量W 6可以为5％、7％、9％、11％、13％、15％或上述任两个数值范围间的任一数值。选用上述材料形成陶瓷涂层，且将无机粉体和第一粘结剂在陶瓷涂层中的质量百分含量调控在上述范围内，更利于陶瓷涂层的作用的发挥。这样，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，无机粉体包括氧化铝、氧化镁、氧化锆或勃姆石中的至少一种，第一粘结剂包括聚丙烯酸、聚偏氟乙烯、聚酰亚胺或聚乙烯醇中的至少一种。上述材料的选用，更利于陶瓷涂层的形成及其作用的发挥。这样，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，陶瓷涂层的涂布重量为5mg/5000mm 2至20mg/5000mm 2。例如，陶瓷涂层的涂布重量为5mg/5000mm 2、10mg/5000mm 2、15mg/5000mm 2、20mg/5000mm 2或上述任两个数值范围间的任一数值。将陶瓷涂层的涂布重量调控在上述范围内，使陶瓷涂层均匀地覆盖在负极集流体上，更利于提高锂金属层电镀的均匀性和稳定性，从而更利于提升电化学装置的倍率性能和循环性能。从而使电化学装置在降低生产成本的情况下，进一步提升电化学装置的倍率性能和循环性能。
在本申请的一些实施例中，陶瓷涂层的厚度为1μm至3μm。例如，陶瓷涂层的厚度可以为1μm、1.5μm、2μm、2.5μm、3μm或上述任两个数值范围间的任一数值。陶瓷涂层的厚度过小(例如小于1μm)，陶瓷涂层的机械强度不够，无法达到本申请的目的；陶瓷涂层的厚度过大(例如大于3μm)，使电化学装置的体积随之增大，将影响电化学装置的能量密度。将陶瓷涂层的厚度调控在上述范围内，使陶瓷涂层在本申请中的作用得以有效发挥。由此，电化学装置在满足能量密度和循环性能的情况下，具有更低的物料生产成本，使电化学装置的生产成本得到有效降低。
在本申请的一些实施例中，负极极片还包括导电层，导电层设置于负极集流体与陶瓷 涂层之间，锂金属层设置在负极集流体与导电层之间。导电层的设置，能够接收正极极片脱出的Li +，抑制析锂及死锂的形成，从而提升电化学装置的安全性能和循环性能。
示例性地，图3示出了本申请一些实施例中的负极极片的结构示意图，如图3所示，负极集流体21在自身厚度方向包括相对设置的第一表面21a和第二表面21b，在第一表面21a和第二表面21b上各自独立地设置有锂金属层22、导电层23和陶瓷涂层40。其中，导电层23设置于负极集流体21与陶瓷涂层40之间，锂金属层22设置在负极集流体21与导电层23之间。可以看到，沿远离第一表面21a的方向，在第一表面21a上依次设置锂金属层22、导电层23和陶瓷涂层40；沿远离第二表面21b的方向，在第二表面21b上依次设置锂金属层22、导电层23和陶瓷涂层40。可以理解，如图3所示的负极极片20中，两层导电层23可以相同或不同，两层陶瓷涂层40可以相同或不同。
在本申请的一些实施例中，导电层包括第二导电剂和第二粘结剂；基于导电层的质量，第二导电剂的质量百分含量W 7为60％至70％，第二粘结剂的质量百分含量W 8为30％至40％。例如，第二导电剂的质量百分含量W 7可以为60％、62％、64％、66％、68％、70％或上述任两个数值范围间的任一数值。例如，第二粘结剂的质量百分含量W 8可以为30％、32％、34％、36％、38％、40％或上述任两个数值范围间的任一数值。选用上述材料形成导电层，且将第二导电剂和第二粘结剂的质量百分含量调控在上述范围内，更利于导电层的作用的发挥。这样，导电层能够接收正极极片脱出的Li +，抑制析锂及死锂的形成，从而提升电化学装置的安全性能和循环性能。
在本申请的一些实施例中，第二导电剂包括无定型碳、单壁碳纳米管或多壁碳纳米管中的至少一种；第二粘结剂包括丁苯橡胶、羧甲基纤维素或聚乙烯醇中的至少一种。上述材料的选用，更利于导电层的形成及其作用的发挥。这样，导电层能够接收正极极片脱出的Li +，抑制析锂及死锂的形成，从而提升电化学装置的安全性能和循环性能。
在本申请的一些实施例中，导电层的厚度为0.5μm至3μm。例如，导电层的厚度可以为0.5μm、1μm、1.5μm、2μm、2.5μm、3μm或上述任两个数值范围间的任一数值。导电的厚度过小(例如小于0.5μm)，导电层的机械强度不够，无法达到本申请的目的；导电层的厚度过大(例如大于3μm)，使电化学装置的体积随之增大，将影响电化学装置的能量密度。将导电层的厚度调控在上述范围内，使导电层在本申请中的作用得以有效发挥。由此，电化学装置具有更低的物料成本的情况下，具有更好的安全性能和循环性能。
本申请对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，正极集流 体可以包含铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体和正极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为5μm至20μm，优选为6μm至18μm。单面正极活性材料层的厚度为30μm至120μm。
本申请对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，负极集流体可以包含铜箔、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，负极集流体的厚度为6μm至10μm。
本申请的电解液还包括锂盐和非水溶剂。
本申请对锂盐没有特别限制，例如，锂盐选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、六氟砷酸锂(LiAsF 6)、高氯酸锂(LiClO 4)、四苯硼锂(LiB(C 6H 5) 4)、甲基磺酸锂(LiCH 3SO 3)、三氟甲磺酸锂(LiCF 3SO 3)、双三氟甲烷磺酰亚胺锂(LiN(SO 2CF 3) 2)、LiC(SO 2CF 3) 3、六氟硅酸锂(LiSiF 6)、双草酸硼酸锂(LiBOB)或二氟硼酸锂(LiF 2OB)中的至少一种。举例来说，锂盐可以选用LiPF 6，因为它具有高的离子电导率并改善循环特性。
本申请对非水溶剂没有特别限制，例如，非水溶剂可为碳酸酯化合物、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为链状碳酸酯化合物、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的实例为碳酸二甲酯(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(EMC)中的至少一种。环状碳酸酯化合物的实例为碳酸亚乙酯(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。氟代碳酸酯化合物的实例为碳酸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。上述羧酸酯化合物的实例为甲酸甲酯、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。上述醚化合物的实例为二丁醚、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。上述其它有机溶剂的实例为丙酸丙酯、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。基于电解液的质量，上述非 水溶剂的总含量为5％至90％，例如5％、10％、15％、20％、25％、30％、35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％或其间的任何范围。
本申请的电化学装置中还包括隔膜，本申请对隔膜没有特别限制，只要能够实现本申请目的即可。
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。在一些实施例中，电化学装置可以包括但不限于：锂金属二次电池、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：将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕得到卷绕结构的电极组件，将电极组件放入包装壳内，将电解液注入包装壳并封口，得到电化学装置；或者，将正极极片、隔膜和负极极片按顺序堆叠，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壳内，将电解液注入包装壳并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装壳中，从而防止电化学装置内部的压力上升、过充放电。
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所述的电化学装置。因此，该电子装置的生产成本也得以降低。
本申请的电子装置没有特别限制，其可以包括但不限于以下种类：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、照相机和家庭用大型蓄电池等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。
测试方法和设备：
物料成本计算逻辑：
单个锂离子电池的物料成本为各组分物料成本的总和。各组分物料即为四大主材和辅材，其中，四大主材为正极活性材料、负极活性材料、隔膜、电解液，辅材为负极集流体、 正极集流体、导电剂、粘结剂、溶剂、胶纸、极耳卷料、包装壳等。每一组分的物料成本＝单价×单位用量。
物料成本占比(％)＝各实施例中锂离子电池的物料成本/对比例1中锂离子电池的物料成本×100％。
首次放电容量测试：
测试温度为25℃，先将锂离子电池满充，再以0.2C恒流放电到3.0V，即为放电容量。
容量保持率测试：
对锂离子电池进行循环容量保持率测试：测试温度为25℃，以0.2C恒流充电到额定电压，恒压充电到0.025C，静置5分钟后以0.2C放电到3.0V。以此步骤得到的容量为初始容量，进行0.2C充电/0.2C放电进行循环测试，以每一次循环后的容量与初始容量做比值，得到容量衰减曲线，从容量衰减曲线直接得到容量保持率。
实施例1-1
<正极极片的制备>
将含锂的正极活性材料LiCoO 2、导电剂导电碳、正极粘结剂聚偏氟乙烯(PVDF)按质量比为95.8:2.0:2.2混合，然后加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75wt％的正极浆料，并搅拌均匀。将正极浆料均匀涂布在厚度为9μm的铝箔的一个表面上，90℃条件下烘干，得到正极活性材料层厚度为100μm的正极极片，然后在该正极极片的另一个表面上重复以上步骤，得到双面涂布有正极活性材料层的正极极片。将正极极片冷压、裁切成规格为74mm×867mm的片材待用。
<负极极片的制备>
将无机粉体氧化铝和第一粘结剂聚丙烯酸按照质量比90:10混合制备得到陶瓷涂层浆料。将陶瓷涂层浆料均匀涂布在厚度为6μm的铜箔的一个表面上，110℃条件下烘干，得到陶瓷涂层厚度为3μm的单面涂布陶瓷涂层的负极极片，然后在该负极极片的另一个表面上重复以上涂布步骤，得到双面涂布有陶瓷涂层的负极极片。将负极极片冷压、裁切成规格为76mm×851mm的片材待用。其中，陶瓷涂层的涂布重量为18.5mg/5000mm 2。
<电解液的制备>
在干燥氩气气氛中，将有机溶剂EC、EMC和DEC按照质量比30:50:20混合，然后向有机溶剂中加入LiPF 6溶解并混合均匀，得到基础溶液，再向基础溶液中加入FEC和LiDFOB。其中，LiPF 6在电解液中的摩尔浓度为1.15mol/L；基于电解液的质量，FEC的 质量百分含量W 1为1％，LiDFOB的质量百分含量W 2为0.6％。
<锂离子电池的制备>
以厚度为9μm的聚乙烯多孔聚合薄膜作为隔膜，将上述制备的正极极片、隔膜、负极极片按顺序叠好，使隔膜处于正负极中间起到隔离的作用，并卷绕得到电极组件。将电极组件置于包装壳中，注入配好的电解液并封装，经过化成、脱气、切边等工艺流程得到锂离子电池。化成工艺为：化成充电电流为0.1C、化成温度为85℃、化成静置时间为180秒。
实施例1-2至实施例1-9
除了按照表1调整相关制备参数，基础溶液和锂盐在电解液中的质量百分含量随之变化，使电解液质量为100％以外，其余与实施例1-1相同。
实施例1-10至实施例1-21
除了按照表1调整相关制备参数以外，其余与实施例1-9相同。
实施例2-1
除了在<正极极片的制备>中加入质量百分含量W 3为3％的正极补锂剂Li 2O，正极活性材料的质量百分含量减少为92.8％以外，其余与实施例1-9相同。
实施例2-2至实施例2-7
除了按照表2调整相关制备参数以外，其余与实施例2-1相同。
实施例3-1
除了在<正极极片的制备>中加入质量百分含量W 4为6％的正极添加剂(无机锂盐Li 5FeO 4和第一导电剂石墨烯的质量比为1:5)，正极活性材料的质量百分含量减少为89.8％以外，其余与实施例1-9相同。
实施例3-2至实施例3-8
除了按照表3调整相关制备参数以外，其余与实施例3-1相同。
实施例3-9
除了在<正极极片的制备>中，在正极活性材料层的两个表面设置陶瓷涂层，陶瓷涂层与实施例1-1中<负极极片的制备>中的陶瓷涂层相同以外，其余与实施例3-3相同。
实施例4-1
<负极极片的制备>
将无机粉体氧化铝和第一粘结剂聚丙烯酸按照质量比90:10混合制备得到陶瓷涂层浆 料。
将第二导电剂无定型碳和第二粘结剂丁苯橡胶按照质量比65:35混合制备得到导电层浆料。
将导电层浆料和陶瓷涂层浆料依次均匀涂布在厚度为6μm的铜箔的一个表面上，110℃条件下烘干，得到导电层厚度为1.5μm、陶瓷涂层厚度为2μm的单面涂布陶瓷涂层的负极极片，然后在该负极极片的另一个表面上重复以上涂布步骤，得到双面涂布有导电层和陶瓷涂层的负极极片。将负极极片冷压、裁切成规格为76mm×851mm的片材待用。其中，导电层的涂布重量为0.5mg/5000mm 2、陶瓷涂层的涂布重量为13.6mg/5000mm 2。
其余与实施例1-9相同。
实施例4-2
除了<正极极片的制备>与实施例3-9相同以外，其余与实施例4-2相同。
实施例4-3至实施例4-4
除了按照表4调整相关制备参数以外，其余与实施例4-2相同。
对比例1
<负极极片的制备>
将负极活性材料石墨、导电剂导电炭黑、粘结剂丁苯橡胶(SBR)按照质量比为85:5:10混合，然后加入去离子水作为溶剂，调配成固含量为70wt％的负极浆料，并搅拌均匀，将负极浆料均匀涂布在厚度为6μm的铜箔的一个表面上，110℃条件下烘干，得到负极活性材料层厚度为130μm的单面涂布负极活性材料层的负极极片，然后在该负极极片的另一个表面上重复以上涂布步骤，得到双面涂布有负极活性材料层的负极极片。将负极极片冷压、裁切成规格为76mm×851mm的片材待用。
<电解液的制备>中不加入FEC和LiDFOB。
其余与实施例1-1相同。
各实施例和对比例的制备参数和性能参数如表1至表4所示。
表1
Figure PCTCN2022078573-appb-000001
注：表1中的“\”表示无对应参数。
从实施例1-1至实施例1-9、实施例1-21和对比例1可以看出，锂离子电池的负极极片不含有负极活性材料时，在负极集流体的表面上设置本申请范围内的陶瓷涂层、且电解液中含有本申请质量百分含量范围内的FEC和LiDFOB时，锂离子电池在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
陶瓷涂层中无机粉料和第一粘结剂的种类通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例1-9至实施例1-14可以看出，选用无机粉料和第一粘结剂的种类在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少 量充放电循环产品需求的情况下，降低了物料成本。
陶瓷涂层中无机粉料和第一粘结剂的质量百分含量通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例1-9、实施例1-15和实施例1-16可以看出，选用无机粉料和第一粘结剂的质量百分含量在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
陶瓷涂层的涂布重量通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例1-9、实施例1-17和实施例1-18可以看出，选用陶瓷涂层的涂布重量在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
陶瓷涂层的厚度通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例1-9、实施例1-19和实施例1-20可以看出，选用陶瓷涂层的厚度在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
表2
Figure PCTCN2022078573-appb-000002
注：表2中的“\”表示无对应参数。
正极补锂剂的种类以及正极补锂剂在正极活性材料层中的质量百分含量通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例1-9、实施例2-1至实施例2-7可以看出，选用正极补锂剂的种类以及质量百分含量在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
表3
Figure PCTCN2022078573-appb-000003
注：表3中的“\”表示无对应参数。
正极添加剂的种类及其在正极活性材料层中的质量百分含量、无机锂盐和第一导电剂的质量比通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例1-9、实施例3-1至实施例3-8可以看出，选用正极添加剂的种类及其在正极活性材料层中的质量百分含量、无机锂盐和第一导电剂的质量比在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
陶瓷涂层在正极极片中的设置通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例3-2和实施例3-9可以看出，选用正极极片中设置有陶瓷涂层的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
表4
Figure PCTCN2022078573-appb-000004
Figure PCTCN2022078573-appb-000005
注：表4中的“\”表示无对应参数。
导电层在负极极片中的设置通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例3-2和实施例4-1、实施例3-9和实施例4-2可以看出，选用负极极片中设置有导电层的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
第二导电层和第二粘结剂在导电层中的质量百分含量通常也会影响锂离子电池的物料成本、首次放电容量和容量保持率。从实施例4-2至实施例4-4可以看出，选用第二导电层和第二粘结剂在导电层中的质量百分含量在本申请范围内的锂离子电池，其在具有良好的首次放电容量、以及能够满足少量充放电循环产品需求的情况下，降低了物料成本。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (15)

  1. 一种电化学装置，包括正极极片和负极极片；
    所述正极极片包括正极集流体以及设置于所述正极集流体至少一个表面上的正极活性材料层，所述正极活性材料层包括含锂的正极活性材料；
    所述负极极片包括负极集流体以及设置于所述负极集流体两个表面上的陶瓷涂层，所述负极极片还包括所述含锂的正极活性材料中的锂离子在充电过程中在所述负极集流体的表面沉积形成的锂金属层，所述锂金属层位于所述负极集流体与所述陶瓷涂层之间；所述负极极片不包含负极活性材料。
  2. 根据权利要求1所述的电化学装置，还包括电解液，所述电解液包括氟代碳酸亚乙酯和二氟草酸硼酸锂；
    基于所述电解液的质量，所述氟代碳酸亚乙酯的质量百分含量W 1为0.1％至10％，所述二氟草酸硼酸锂的质量百分含量W 2为0.05％至5％。
  3. 根据权利要求1所述的电化学装置，其中，所述含锂的正极活性材料包括钴酸锂、锰酸锂、镍钴锰酸锂、钛酸锂或氟酸锂中的至少一种。
  4. 根据权利要求1所述的电化学装置，其中，所述正极活性材料层还包括正极补锂剂；
    所述正极补锂剂包括Li 2O或Li xMO y中的至少一种，2≤x≤6，2≤y≤5，M包括Al、Ni、Co、Mg、Mn、Cu、Fe或Ti中的至少一种；
    基于所述正极活性材料层的质量，所述正极补锂剂的质量百分含量W 3为3％至10％。
  5. 根据权利要求1所述的电化学装置，其中，所述正极活性材料层还包括正极添加剂，所述正极添加剂包括无机锂盐和第一导电剂形成的复合材料，所述无机锂盐与所述第一导电剂的质量比为1:3至1:7；
    基于所述正极活性材料层，所述正极添加剂的质量百分含量W 4为4％至8％。
  6. 根据权利要求5所述的电化学装置，其中，所述无机锂盐包括Li sQ aN bO t，2≤s≤8，0≤a≤1，0≤b≤1，a+b≥1，2≤t≤6，Q选自Fe、Co、Mn、Ni、Zr、V、Nb或Mo中的任一种，N选自Al、Mg、Ti、Cr、Y、Sr、Si、W、Ga或Zn中的任一种；
    所述第一导电剂包括石墨烯、乙炔黑、单壁碳纳米管或多壁碳纳米管中的至少一种。
  7. 根据权利要求1所述的电化学装置，其中，所述正极极片还包括所述陶瓷涂层，所述陶瓷涂层设置于所述正极活性材料层的表面。
  8. 根据权利要求1所述的电化学装置，其中，所述陶瓷涂层包括无机粉体和第一粘结 剂；
    基于所述陶瓷涂层的质量，所述无机粉体的质量百分含量W 5为85％至95％，所述第一粘结剂的质量百分含量W 6为5％至15％。
  9. 根据权利要求8所述的电化学装置，其中，所述无机粉体包括氧化铝、氧化镁、氧化锆或勃姆石中的至少一种，所述第一粘结剂包括聚丙烯酸、聚偏氟乙烯、聚酰亚胺或聚乙烯醇中的至少一种。
  10. 根据权利要求1所述的电化学装置，其中，所述陶瓷涂层的涂布重量为5mg/5000mm 2至20mg/5000mm 2。
  11. 根据权利要求1所述的电化学装置，其中，所述陶瓷涂层的厚度为1μm至3μm。
  12. 根据权利要求1所述的电化学装置，其中，所述负极极片还包括导电层，所述导电层设置于所述负极集流体与所述陶瓷涂层之间，所述锂金属层设置在所述负极集流体与所述导电层之间。
  13. 根据权利要求12所述的电化学装置，其中，所述导电层包括第二导电剂和第二粘结剂；
    基于所述导电层的质量，所述第二导电剂的质量百分含量W 7为60％至70％，所述第二粘结剂的质量百分含量W 8为30％至40％。
  14. 根据权利要求13所述的电化学装置，其中，所述第二导电剂包括无定型碳、单壁碳纳米管或多壁碳纳米管中的至少一种；
    所述第二粘结剂包括丁苯橡胶、羧甲基纤维素或聚乙烯醇中的至少一种。
  15. 一种电子装置，包括权利要求1至14中任一项所述的电化学装置。
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