WO2023039748A9 - 一种电化学装置和电子装置 - Google Patents

一种电化学装置和电子装置 Download PDF

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WO2023039748A9
WO2023039748A9 PCT/CN2021/118515 CN2021118515W WO2023039748A9 WO 2023039748 A9 WO2023039748 A9 WO 2023039748A9 CN 2021118515 W CN2021118515 W CN 2021118515W WO 2023039748 A9 WO2023039748 A9 WO 2023039748A9
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Prior art keywords
positive electrode
electrochemical device
active material
lithium
electrode active
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PCT/CN2021/118515
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English (en)
French (fr)
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WO2023039748A1 (zh
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张洋洋
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宁德新能源科技有限公司
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Priority to PCT/CN2021/118515 priority Critical patent/WO2023039748A1/zh
Priority to AU2021464880A priority patent/AU2021464880A1/en
Priority to CN202180009725.5A priority patent/CN115004413A/zh
Publication of WO2023039748A1 publication Critical patent/WO2023039748A1/zh
Publication of WO2023039748A9 publication Critical patent/WO2023039748A9/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • 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 field of electrochemistry, in particular to an electrochemical device and an electronic device.
  • lithium-ion batteries Due to its high energy density, long cycle life and no memory effect, lithium-ion batteries are widely used in wearable devices, smart phones, drones, electric vehicles and large energy storage devices, and have become the most developed in the world today. It is a potential new green chemical power source, but it also puts forward higher requirements for the comprehensive performance of lithium-ion batteries.
  • the performance of lithium-ion batteries mainly depends on the characteristics of the positive electrode, negative electrode, electrolyte and separator, among which the active materials in the positive and negative electrodes are one of the important factors affecting the performance of lithium-ion batteries.
  • Ternary layered nickel-cobalt lithium manganese oxide, lithium manganese oxide, and lithium iron phosphate are widely used in the field of electric vehicles and electric bicycles as common positive electrode materials, but there are still short battery life, poor cycle performance, and poor high-temperature and low-temperature storage performance. At least one of the problems, that is, the comprehensive performance of lithium-ion batteries still needs to be improved urgently.
  • the purpose of this application is to provide an electrochemical device and an electronic device to improve the comprehensive performance of the electrochemical device.
  • the first aspect of the present application provides an electrochemical device, which includes a positive electrode sheet, the positive electrode sheet includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material, and the elements in the positive electrode active material include Li, Mn, Ni, Co and Fe, wherein the positive electrode active material satisfies at least one of the following characteristics: (i) the ratio A of the atomic number of Mn to the total number of Ni, Co and Fe atoms is 3.5 to 40; (ii) the atomic number of Li and Mn, Ni , the ratio B of the total number of Co and Fe atoms is 0.51 to 0.79.
  • the electrochemical device has a long service life and good high-temperature storage performance , low temperature performance and cycle performance, etc.
  • low temperature means that the temperature is less than or equal to 0°C
  • high temperature means that the temperature is greater than or equal to 40°C.
  • the ratio A of the atomic number of Mn to the total number of Ni, Co and Fe atoms can be 3.5, 5, 10, 15, 20, 25, 30, 35, 40 or any range therebetween.
  • the inventors of the present application have found that when the ratio A of the atomic number of Mn to the total number of Ni, Co and Fe atoms is too small (for example, less than 3.5), the low temperature performance of the electrochemical device deteriorates, for example, the capacity at low temperature The retention rate decreases, which affects the overall performance of the electrochemical device.
  • the positive pole piece When the ratio A of the number of atoms of Mn to the total number of atoms of Ni, Co and Fe is too large (for example, greater than 40), the positive pole piece is prone to manganese dissolution at high temperatures, resulting in reduced high-temperature storage performance and cycle performance of the electrochemical device. The service life of the electrochemical device is shortened, thereby affecting the comprehensive performance of the electrochemical device.
  • the ratio A of the atomic number of Mn to the total number of Ni, Co and Fe atoms within the above range, the transmission efficiency of lithium ions can be improved, the manganese dissolution phenomenon of the positive electrode sheet can be effectively suppressed, and it is beneficial to improve the low temperature of the electrochemical device at the same time. Performance, high-temperature storage performance and cycle performance, prolong the service life of the electrochemical device, thereby improving the overall performance of the electrochemical device.
  • the ratio B of the number of Li atoms to the total number of Mn, Ni, Co and Fe atoms can be 0.51, 0.53, 0.55, 0.58, 0.6, 0.65, 0.7, 0.73, 0.76, 0.79 or any range therebetween.
  • the inventors of the present application have found that when the ratio B of the atomic number of Li to the total number of atoms of Mn, Ni, Co and Fe is too small (for example, less than 0.51), the high-temperature storage performance and cycle performance of the electrochemical device deteriorate, and the use The lifespan is shortened, thereby affecting the overall performance of the electrochemical device.
  • the ratio B of the atomic number of Li to the total number of atoms of Mn, Ni, Co, and Fe is too large (for example, greater than 0.51), the low-temperature performance of the electrochemical device will deteriorate, and the overall performance of the electrochemical device will also be affected.
  • the ratio B of the number of Li atoms to the total number of Mn, Ni, Co, and Fe atoms within the above range, the transmission efficiency of lithium ions can be improved, and the manganese dissolution phenomenon of the positive electrode sheet can be effectively suppressed, thereby improving the performance of the electrochemical device at the same time.
  • Low temperature performance, high temperature storage performance and cycle performance prolong the service life of the electrochemical device, and improve the comprehensive performance of the electrochemical device.
  • the value of A/B may be 6, 10, 15, 20, 25, 30, 35, 40 or any range therebetween.
  • the inventors of the present application have found that by adjusting the value of A/B within the above range, it is beneficial to obtain good low-temperature performance, high-temperature storage performance and cycle performance, as well as a long service life, that is, electric The chemical device has good comprehensive performance.
  • the positive pole piece in the aforementioned electrochemical device and lithium metal are assembled into a button battery, and in the differential curve of the charging capacity of the first cycle of the button battery, the peak value is between 4.4V and 4.6V.
  • the ratio P of the area of to the area of the peak between 3.9V and 4.6V is 0.005 to 0.2, preferably 0.05 to 0.2.
  • the value of P can be 0.005, 0.01, 0.05, 0.1, 0.15, 0.2 or any range therebetween.
  • the inventors of the present application found that when the value of P is too small (eg, less than 0.005), the high-temperature storage performance and cycle performance of the electrochemical device deteriorate.
  • the electrochemical device When the value of P is too large (for example, greater than 0.2), the electrochemical device will experience significant low-temperature performance degradation.
  • the stability of the positive electrode active material is improved, which can effectively improve the manganese dissolution phenomenon of the positive electrode sheet, and can meet the lithium supply demand of the electrochemical device during the cycle process, which is conducive to improving the battery life. Cycling performance and high temperature storage performance of chemical devices.
  • 0.21-0.0056A ⁇ P ⁇ 0.2 the value of P can be 0.19, 0.192, 0.194, 0.196, 0.198, 0.2 or any range therebetween.
  • the inventors of the present application found that by adjusting the values of A and P to satisfy the above relationship, it is beneficial to improve the high temperature cycle performance of the electrochemical device.
  • the positive pole piece in the aforementioned electrochemical device and lithium metal are assembled into a button battery, and the charge-discharge efficiency E of the button battery at 2.8V to 4.6V is 90% to 110%.
  • the charge and discharge efficiency E of the button battery in the first cycle from 2.8V to 4.6V is 90%, 92%, 95%, 98%, 100%, 102%, 105%, 108%, 110%, or any value in between. scope.
  • the Dv50 of the positive electrode active material is 8 ⁇ m to 14 ⁇ m, preferably 8 ⁇ m to 13 ⁇ m, and the Dv90 of the positive electrode active material is less than or equal to 30 ⁇ m, 1.2 ⁇ (Dv90-Dv10)/Dv50 ⁇ 2.2.
  • the Dv50 of the positive electrode active material may be 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m or any range therebetween.
  • the inventors of the present application found that when the Dv50 of the positive electrode active material is too small (for example, less than 8 ⁇ m), the positive electrode active material is prone to side reactions with the electrolyte, thereby affecting the high-temperature storage performance and cycle performance of the electrochemical device. As the Dv50 of the positive electrode active material increases, the side reaction between the positive electrode active material and the electrolyte also decreases.
  • the Dv50 of the positive electrode active material is too large (for example greater than 14 ⁇ m), the low temperature performance of the electrochemical device will be deteriorated.
  • the Dv50 of the positive electrode active material is beneficial to improve the high-temperature storage performance, low-temperature performance and cycle performance of the electrochemical device, and prolong the service life of the electrochemical device.
  • the Dv90 of the positive electrode active material may be 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m or any range therebetween.
  • the value of (Dv90-Dv10)/Dv50 can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2 or any range therebetween.
  • the inventors of the present application have found that by adjusting the values of Dv50, Dv90 and (Dv90-Dv10)/Dv50 of the positive electrode active material within the above range, it is beneficial to improve the high-temperature storage performance, low-temperature performance and cycle performance of the electrochemical device.
  • the present application has no special limitation on the Dv10 of the positive electrode active material, as long as the range of (Dv90-Dv10)/Dv50 can be satisfied, for example, the Dv10 of the positive electrode active material can be 1.0 ⁇ m to 17.9 ⁇ m, for example, the Dv10 of the positive electrode active material Dv10 may be 1.0 ⁇ m, 1.4 ⁇ m, 5.6 ⁇ m, 11.4 ⁇ m, 13.9 ⁇ m, 16.0 ⁇ m, 17.9 ⁇ m or any range therebetween.
  • the positive electrode active material includes spinel lithium manganese oxide (LiMn 2 O 4 ) and at least one of nickel-cobalt lithium manganese oxide, lithium iron phosphate (LiFePO 4 ) or lithium-rich manganese-based materials .
  • the inventors of the present application have found that by selecting the above-mentioned positive electrode active materials, it is beneficial to improve the overall performance of the electrochemical device, for example, simultaneously improve the low-temperature performance, high-temperature storage performance and cycle performance of the electrochemical device, and prolong the electrochemical device. service life.
  • the present application has no special limitation on the preparation method of LiMn 2 O 4 , as long as the purpose of the present application can be achieved, for example, it can be synthesized by lithium carbonate and manganese dioxide at 700°C to 750°C, and the synthesis temperature is preferably 730°C.
  • the present application has no special restrictions on lithium nickel cobalt manganate, as long as the purpose of this application can be achieved, for example, it may include but not limited to layered nickel cobalt manganese oxide lithium, specifically, layered nickel cobalt lithium manganese oxide conforms to the general formula Li (Ni x1 Co y1 Mn 1-x1-y1 )O 2 , where x1 ⁇ 0, y1 ⁇ 0, x1+y1 ⁇ 1.
  • lithium-rich manganese-based materials conform to the general formula Li 2-(x2+y2+z1) Ni x2 Co y2 Mn z1 O 2 , Among them, x2 ⁇ 0, y2 ⁇ 0, z1>0, x2+y2+z1 ⁇ 1.
  • the content of the positive electrode active material in the positive electrode material layer is 320 g/m 2 to 480 g/m 2 .
  • the content of the positive electrode active material in the positive electrode material layer is 320g/m 2 , 350g/m 2 , 380g/m 2 , 400g/m 2 , 420g/m 2 , 440g/m 2 , 460g/m 2 , 480g/m 2 m 2 or any range in between.
  • the inventors of the present application found that when the content of the positive electrode active material in the positive electrode material layer is too low (for example, less than 320 g/m 2 ), the energy density of the electrochemical device will be affected.
  • the content of the positive electrode active material in the positive electrode material layer is too high (for example, higher than 480 g/m 2 ), it will make it difficult for some positive electrode active materials to perform their functions, resulting in waste of materials and affecting the cost of the electrochemical device.
  • the electrochemical device further includes an electrolyte, the electrolyte includes a compound containing a sulfur-oxygen double bond, and the compound containing a sulfur-oxygen double bond includes 1,3-propane sultone and/or vinyl sulfate, based on
  • the mass percentage of the sulfur-oxygen double bond compound is 0.01% to 2%.
  • the mass percentage of the compound containing sulfur and oxygen double bonds can be 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, or between any range of .
  • the above-mentioned compound containing sulfur-oxygen double bonds is included in the electrolyte and its mass percentage is within the above-mentioned range, which is conducive to the formation of a stable solid electrolyte interface (SEI) at the negative electrode to inhibit the interaction between the electrolyte and the negative electrode active material.
  • SEI solid electrolyte interface
  • CEI catholyte interface
  • the positive electrode may refer to the positive electrode sheet
  • the negative electrode may refer to the negative electrode sheet.
  • the positive electrode sheet can also include a positive current collector.
  • This application has no special restrictions on the positive current collector, as long as the purpose of this application can be achieved, for example, it can include but not limited to aluminum foil, aluminum alloy foil or composite current collectors, etc. .
  • the thickness of the positive electrode collector there is no particular limitation on the thickness of the positive electrode collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8 ⁇ m to 12 ⁇ m.
  • the positive electrode material layer may also include a binder.
  • the present application has no special restrictions on the binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to polyacrylic acid, sodium polyacrylate, polyacrylic acid At least one of potassium, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethylcellulose, sodium carboxymethylcellulose, polyimide, polyamideimide, styrene-butadiene rubber or polyvinylidene fluoride A sort of.
  • a conductive agent may also be included in the positive electrode material layer, and the present application has no special limitation on the conductive agent, as long as the purpose of the application can be realized, for example, it may include but not limited to conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber, flake graphite, Ketjen black, graphene, metal material or conductive polymer.
  • the aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the aforementioned carbon fibers may include, but are not limited to, vapor grown carbon fibers (VGCF) and/or carbon nanofibers.
  • the above metal material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the aforementioned conductive polymer may include but not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the positive electrode sheet may further include a conductive layer located between the positive electrode current collector and the positive electrode material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, for example, may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • the electrochemical device in the present application may also include a negative electrode sheet.
  • the negative electrode sheet in the present application is not particularly limited as long as the purpose of the application can be achieved.
  • the negative electrode sheet usually includes a negative electrode collector.
  • the negative electrode current collector is not particularly limited, as long as the purpose of this application can be achieved, it can include but not limited to copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or composite current collector.
  • the thickness of the current collector of the negative electrode there is no particular limitation on the thickness of the current collector of the negative electrode, as long as the purpose of the present application can be achieved, for example, the thickness is 4 ⁇ m to 12 ⁇ m.
  • the negative electrode sheet may further include a negative electrode material layer, and the negative electrode material layer includes a negative electrode active material.
  • the present application has no special restrictions on the negative electrode active material, as long as the purpose of the present application can be achieved, for example, it can include but not limited to natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, silicon-carbon composite At least one of Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , lithiated TiO 2 -Li 4 Ti 5 O 12 with spinel structure, and Li-Al alloy.
  • the negative electrode material layer may also include a conductive agent.
  • the present application has no special limitation on the conductive agent, as long as the purpose of the present application can be achieved, for example, it may include but not limited to at least one of the above-mentioned conductive agents.
  • the negative electrode material layer may also include a binder, and the present application has no special restrictions on the binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to at least one of the above-mentioned binders .
  • the negative electrode sheet may further include a conductive layer, and the conductive layer is located between the negative electrode current collector and the negative electrode material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, and the conductive layer may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • the electrochemical device of the present application also includes a separator, which is not particularly limited in the present application, as long as the purpose of the application can be achieved, such as but not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene Ethylene-based polyolefin (PO) separator, polyester film (such as polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide film (PA) , spandex, aramid film, woven film, non-woven film (non-woven fabric), microporous film, composite film, separator paper, rolled film or spun film.
  • a separator which is not particularly limited in the present application, as long as the purpose of the application can be achieved, such as but not limited to polyethylene (PE), polypropylene (PP), polytetrafluoroethylene Ethylene-based polyolefin (PO) separator, polyester film (such as polyethylene terephthalate (PET) film), cellulose film,
  • the separator of the present application may have a porous structure, and the pore size is not particularly limited as long as the purpose of the present application can be achieved, for example, the pore size may be 0.01 ⁇ m to 1 ⁇ m.
  • the thickness of the isolation film is not particularly limited, as long as the purpose of the present application can be achieved, for example, the thickness may be 5 ⁇ m to 500 ⁇ m.
  • a separator may include a substrate layer and a surface treatment layer.
  • the substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer can include but not limited to polyethylene, polypropylene, polyethylene terephthalate or polyimide, etc. at least one of .
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material.
  • the inorganic material layer may include but not limited to inorganic particles and binders, and the present application has no particular limitation on inorganic particles, for example, may include but not limited to aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, At least one of ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the present application has no special limitation on the binder, for example, it may include but not limited to polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate , polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the polymer material may include but not limited to polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl ether, polyvinylidene fluoride At least one of ethylene, poly(vinylidene fluoride-hexafluoropropylene), and the like.
  • lithium salts may also be included in the electrolyte.
  • This application has no particular limitation on lithium salts, as long as the purpose of this application can be achieved, for example, it may include but not limited to LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiSiF 6 , LiBOB or lithium difluoroborate A sort of.
  • the lithium salt comprises LiPF 6 .
  • non-aqueous solvents may also be included in the electrolyte, and the present application has no special restrictions on lithium salt non-aqueous solvents, as long as the purpose of the application can be achieved, for example, it may include but not limited to carbonate compounds, carboxylate compounds Compound, ether compound or at least one of other organic solvents.
  • the above-mentioned carbonate compounds may include but not limited to at least one of chain carbonate compounds, cyclic carbonate compounds, and fluorocarbonate compounds.
  • Chain carbonate compound can include but not limited to dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC) or at least one of methyl ethyl carbonate (MEC).
  • the cyclic carbonate may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or vinylethylene carbonate (VEC).
  • Fluorocarbonate compounds may include, but are not limited to, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2- At least one of difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2,2-tetrafluoroethylene carbonate 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • carboxylate compounds may include but are not limited to methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyl At least one of lactone, decanolactone, valerolactone, mevalonolactone or caprolactone.
  • the aforementioned ether compounds may include, but are not limited to, dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxy At least one of methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but not limited to dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2- At least one of pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.
  • the electrochemical device of the present application is not particularly limited, and it may include any device that undergoes an electrochemical reaction.
  • the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery, among others.
  • the preparation process of electrochemical devices is well known to those skilled in the art, and the present application is not particularly limited.
  • it may include but not limited to the following steps: stack the positive electrode sheet, separator and negative electrode sheet in sequence, and as required Winding, folding and other operations to obtain the electrode assembly with a winding structure, put the electrode assembly into the packaging bag, inject the electrolyte solution into the packaging bag and seal it to obtain an electrochemical device; or, put the positive electrode sheet, separator and negative electrode
  • the pole pieces are stacked in order, and then the four corners of the entire laminated structure are fixed with adhesive tape to obtain the electrode assembly of the laminated structure.
  • the electrode assembly is placed in the packaging bag, and the electrolyte is injected into the packaging bag and sealed to obtain an electrochemical device.
  • overcurrent prevention elements, guide plates, etc. can also be placed in the packaging bag as needed, so as to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the second aspect of the present application provides an electronic device, comprising the electrochemical device in any one of the foregoing embodiments of the present application.
  • the electronic device of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • the application provides an electrochemical device, which includes a positive electrode sheet, the positive electrode sheet includes a positive electrode material layer, the positive electrode material layer includes a positive electrode active material, and the elements in the positive electrode active material include Li, Mn, Ni, Co and Fe, wherein,
  • the positive electrode active material satisfies at least one of the following characteristics: (i) the ratio A of the atomic number of Mn to the total number of Ni, Co and Fe atoms is 3.5 to 40; (ii) the atomic number of Li and Mn, Ni, Co and Fe The ratio B of the total number of atoms is 0.51 to 0.79.
  • the electrochemical device obtained has good overall performance, for example, an electrochemical device At the same time, it has a long service life, good high-temperature storage performance, low-temperature performance and cycle performance, etc.
  • FIG. 1 is a capacity differential curve of a button battery assembled with a positive pole piece and lithium metal in Example 17 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 test method is: fully charge the lithium-ion battery to 2.8V, disassemble the positive electrode piece, soak it in DMC solution for 24 hours, and then dry it for later use.
  • the processed positive pole piece is weighed, digested, diluted, then use an inductively coupled plasma emission spectrometer (model is Thermo ICAP6300) to test the mass content of different elements, each embodiment or comparative example tests 6 positive pole pieces, and then Take the average as the final result.
  • the mass percent content of the element the mass of the element/the mass of the positive pole piece ⁇ 100%.
  • the mass of the positive pole piece is the mass after subtracting the positive current collector.
  • Figure 1 shows the differential curve of the first cycle charging capacity of the button battery obtained by assembling the positive pole piece and lithium metal in Example 17. After measurement, the peak area in the range of 4.4V to 4.6V is recorded as S1 is 10.7, 3.9V The peak area in the range from 4.6V to 4.6V was recorded as S2 as 100.4, and P was calculated as 0.11.
  • the ordinate dQ/dV in the figure refers to the ratio of the difference of the capacity measured twice before and after to the difference of the voltage corresponding to the capacity.
  • the lithium-ion battery is charged with a constant current and constant voltage at a charging current of 0.5C (that is, the current value that completely discharges the theoretical capacity within 2 hours) until the upper limit voltage is about 4.2V. Then a constant current discharge was performed at a discharge current of 0.2C until the final voltage was about 2.8V, and the first discharge capacity was recorded. The ratio of the initial discharge capacity to the mass of the positive electrode sheet is recorded as the gram capacity of the positive electrode sheet. For each example or comparative example, 4 positive pole pieces were tested, and the average value was taken as the final result. Wherein, the mass of the positive pole piece is the mass after subtracting the positive current collector.
  • the thickness of the lithium-ion battery to be tested and record it as the initial thickness.
  • the lithium-ion battery is charged with constant current and constant voltage at a charging current of 0.5C until the upper limit voltage is about 4.2V, and then discharged at a constant current of 1C until the final voltage About 2.8V, record the discharge capacity of the first cycle as the initial discharge capacity. Then carry out 500 charge and discharge cycles in the same steps, record the discharge capacity of the lithium-ion battery after 500 cycles as the cycle discharge capacity, and test the thickness of the lithium-ion battery after 500 cycles as the cycle thickness.
  • the cycle capacity retention rate of the lithium-ion battery at 45 °C was calculated by the following formula:
  • the cyclic expansion rate of the lithium-ion battery at 45 °C was calculated by the following formula:
  • Each embodiment or comparative example tests 4 lithium-ion batteries, and taking the average value is the final test result.
  • the lithium-ion battery in an environment of 25°C for 30 minutes, then charge it to 4.2V at a rate of 0.2C, then charge it at a constant voltage of 4.2V to 0.05C, let it stand for 30 minutes, and then discharge it at a rate of 0.5C to 2.8V, record the discharge capacity at this time as the capacity of the lithium-ion battery before storage; then store the fully charged battery in an oven at about 60°C for about 7 days, and test its capacity after storage.
  • the specific test procedure is as follows: the lithium-ion battery was left to stand in an environment of 25°C for 30 minutes, then charged to 4.2V at a constant current rate of 0.2C, charged to 0.05C at a constant voltage of 4.2V, left to stand for 30 minutes, and then charged at a rate of 0.5C C rate discharge to 2.8V, record the discharge capacity at this time as the stored capacity of the lithium-ion battery.
  • the high-temperature storage capacity retention rate of lithium-ion batteries at 60°C is calculated by the following formula:
  • 60°C high temperature storage capacity retention rate capacity after storage / capacity before storage ⁇ 100%.
  • Each embodiment or comparative example tests 4 lithium-ion batteries, and taking the average value is the final result.
  • the positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 12 ⁇ m, and the aluminum foil was dried at 120° C. for 1 hour to obtain a positive electrode sheet coated with a positive electrode material layer on one side.
  • the positive electrode active material was The content in the positive electrode material layer was 425 g/m 2 .
  • Repeat the above steps on the other surface of the aluminum foil to obtain a positive electrode sheet coated with positive active material on both sides. Then, after cold pressing, cutting into pieces, and slitting, it was dried under vacuum conditions at 120° C. for 1 hour to obtain a positive electrode sheet with a size of (74 mm ⁇ 867 mm).
  • LiMn 2 O 4 is synthesized by lithium carbonate and manganese dioxide at 730 ° C, the mass ratio of lithium carbonate and manganese dioxide is 0.55, the Dv50 of the positive electrode active material is 11 ⁇ m, and the Dv90 is 19 ⁇ m.
  • Negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC) are mixed according to the mass ratio of 95:2:2:1, add to Ionized water is used to obtain negative electrode slurry under the action of a vacuum mixer, wherein the solid content of the negative electrode slurry is 75%.
  • the negative electrode slurry is evenly coated on one surface of the negative electrode current collector copper foil with a thickness of 12 ⁇ m, and the copper foil is dried at 120 ° C to obtain a negative electrode sheet coated with a negative electrode material layer on one side.
  • the negative electrode active material is in The content in the positive and negative electrode material layers is 112 g/m 2 .
  • Repeat the above steps on the other surface of the aluminum foil to obtain a negative electrode sheet coated with negative active materials on both sides.
  • the organic solvents propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) were mixed in a mass ratio of 1:1:1, and then added to the organic solvent Lithium salt lithium hexafluorophosphate (LiPF 6 ) was added to dissolve and mixed uniformly to obtain an electrolyte solution.
  • LiPF 6 lithium hexafluorophosphate
  • the concentration of LiPF 6 in the electrolyte is 1.15mol/L.
  • a porous polyethylene (PE) film (provided by Celgard) with a thickness of 7 ⁇ m and a pore size of 0.1 ⁇ m was used.
  • the electrode assembly is obtained by winding.
  • Example 2 In Example 2 to Example 11, except that the types and mass ratios of positive electrode active materials are adjusted according to Table 1, the rest are the same as Example 1.
  • Example 12 to Example 15 in addition to adjusting the mass ratio of lithium carbonate and manganese dioxide to 0.5, 0.55, 0.57, and 0.59 in order to make the B value as shown in Table 1, adjust the type and quality of the positive electrode active material according to Table 1 Except ratio, all the other are identical with embodiment 1.
  • Example 16 to Example 19 except that the type of positive electrode active material and its mass ratio are adjusted according to Table 2 so that the P value is as shown in Table 2, the rest are the same as Example 13.
  • Example 24 to Example 28 except that the particle size of the positive electrode active material is adjusted according to Table 4, the rest are the same as Example 13.
  • Comparative Example 4 and Comparative Example 5 except that the content of the positive electrode active material in the positive electrode material layer and the content of the negative electrode active material in the negative electrode material layer were adjusted according to Table 3, the rest were the same as in Example 13.
  • Example 1 With reference to Table 1, it can be seen from Example 1 to Example 15 and Comparative Example 1 that when the value of positive electrode active material A and/or B is within the scope of the present application, the overall performance of the electrochemical device can be improved, such as electrochemical The device also has good low-temperature performance, high-temperature storage performance and high-temperature cycle performance, and the first cycle charge and discharge efficiency of the button battery is significantly improved.
  • Example 12 From Example 12 to Example 15, it can be seen that when the value of A is constant, as the value of B increases, the specific capacity of the positive electrode sheet shows a downward trend, and the high-temperature storage performance and high-temperature cycle performance show a gradual improvement trend .
  • Example 13 With reference to Table 2, it can be seen from Example 13, Example 16 to Example 19, Comparative Example 2 and Comparative Example 3 that when the P value is within the scope of the application, the overall performance of the electrochemical device can be improved, such as electrochemical
  • the chemical device has good low temperature performance, high temperature storage performance and high temperature cycle performance at the same time.
  • the content of the positive electrode active material in the positive electrode material layer usually affects the overall performance of the electrochemical device. Referring to Table 3, it can be seen from Example 13, Example 20 to Example 23, Comparative Example 4 and Comparative Example 5 that when the positive electrode When the content of the active material in the positive electrode material layer is within the scope of the present application, the obtained electrochemical device has good comprehensive performance, for example, the electrochemical device has good low-temperature performance, high-temperature storage performance and high-temperature cycle performance at the same time.
  • the particle size of the positive electrode active material and the relationship between the particle sizes usually affect the overall performance of the electrochemical device.
  • Table 4 it can be seen from Example 13, Example 24 to Example 28, and Comparative Example 6 that when the positive electrode activity When the values of Dv50, Dv90 and Dv90-Dv10)/Dv50 of the material are within the scope of the present application, the obtained electrochemical device has good overall performance, for example, the electrochemical device has good low-temperature performance, high-temperature storage performance and high-temperature storage performance at the same time. cycle performance.

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Abstract

一种电化学装置和电子装置，电化学装置包括正极极片，正极极片包括正极材料层，正极材料层包括正极活性材料，正极活性材料中的元素包括Li、Mn、Ni、Co和Fe，其中，正极活性材料满足以下特征中的至少一种：(ⅰ)Mn的原子数与Ni、Co和Fe原子总数的比值A为3.5至40；(ⅱ)Li的原子数与Mn、Ni、Co和Fe原子总数的比值B为0.51至0.79。通过调控正极活性材料中的元素满足A和/或B的范围，有利于提高电化学装置的综合性能。

Description

一种电化学装置和电子装置 技术领域
本申请涉及电化学领域，特别是涉及一种电化学装置和电子装置。
背景技术
锂离子电池由于具有高能量密度、长循环寿命及无记忆效应等优点而被广泛应用于穿戴设备、智能手机、无人机、电动汽车及大型储能设备等领域，已成为当今世界最具发展潜力的新型绿色化学电源，但也对锂离子电池的综合性能提出更高的要求。
锂离子电池的性能主要取决于正极、负极、电解液和隔离膜的特性，其中，正极和负极中的活性材料是影响锂离子电池性能的重要因素之一。三元层状镍钴锰酸锂、锰酸锂、磷酸铁锂作为常用的正极材料被广泛应用与电动汽车及电动自行车领域，但仍存在电池寿命短、循环性能差、高温和低温存储性能差等问题中的至少一种问题，也即锂离子电池的综合性能仍亟待提高。
发明内容
本申请的目的在于提供一种电化学装置和电子装置，以提高电化学装置的综合性能。
本申请的第一方面提供一种电化学装置，其包括正极极片，正极极片包括正极材料层，正极材料层包括正极活性材料，正极活性材料中的元素包括Li、Mn、Ni、Co和Fe，其中，正极活性材料满足以下特征中的至少一种：(ⅰ)Mn的原子数与Ni、Co和Fe原子总数的比值A为3.5至40；(ⅱ)Li的原子数与Mn、Ni、Co和Fe原子总数的比值B为0.51至0.79。不限于任何理论，通过调控正极活性材料中的元素满足A和/或B的范围，有利于提高电化学装置的综合性能，例如，电化学装置同时具有较长的使用寿命、良好的高温存储性能、低温性能和循环性能等。在本申请中，低温是指温度小于或等于0℃，高温是指温度大于或等于40℃。
例如，Mn的原子数与Ni、Co和Fe原子总数的比值A可以为3.5、5、10、15、20、25、30、35、40或为其间的任意范围。不限于任何理论，本申请发明人发现，当Mn的原子数与Ni、Co和Fe原子总数的比值A过小时(例如小于3.5)，电化学装置的低温性能恶化，例如，在低温下的容量保持率降低，影响电化学装置的综合性能。当Mn的原子数与Ni、Co和Fe原子总数的比值A过大时(例如大于40)，正极极片在高温下容易出现锰溶出现象，导致电化学装置的高温存储性能和循环性能降低、缩短电化学装置的使用寿命， 从而影响电化学装置的综合性能。通过调控Mn的原子数与Ni、Co和Fe原子总数的比值A在上述范围内，可以提高锂离子的传输效率、有效抑制正极极片的锰溶出现象等，有利于同时提高电化学装置的低温性能、高温存储性能和循环性能，延长电化学装置的使用寿命，从而提高电化学装置的综合性能。
例如，Li的原子数与Mn、Ni、Co和Fe原子总数的比值B可以为0.51、0.53、0.55、0.58、0.6、0.65、0.7、0.73、0.76、0.79或为其间的任意范围。不限于任何理论，本申请发明人发现，当Li的原子数与Mn、Ni、Co和Fe原子总数的比值B过小时(例如小于0.51)，电化学装置的高温存储性能和循环性能恶化、使用寿命缩短，从而影响电化学装置的综合性能。当Li的原子数与Mn、Ni、Co和Fe原子总数的比值B过大时(例如大于0.51)，电化学装置的低温性能恶化，也会影响电化学装置的综合性能。通过调控Li的原子数与Mn、Ni、Co和Fe原子总数的比值B在上述范围内，可以提高锂离子的传输效率、有效抑制正极极片的锰溶出现象等，从而同时提高电化学装置的低温性能、高温存储性能和循环性能，延长电化学装置的使用寿命，提高电化学装置的综合性能。
在本申请的一些实施方案中，6≤A/B≤40。例如，A/B的值可以为6、10、15、20、25、30、35、40或为其间的任意范围。不限于任何理论，本申请发明人发现，通过调控A/B的值在上述范围内，有利于得到同时具有良好的低温性能、高温存储性能和循环性能，以及较长的使用寿命，也即电化学装置具有良好的综合性能。
在本申请的一些实施方案中，将前述电化学装置中的正极极片与锂金属组装为扣式电池，在扣式电池的首圈充电容量微分曲线中，在4.4V至4.6V之间峰的面积与3.9V至4.6V之间峰的面积的比值P为0.005至0.2，优选为0.05至0.2。例如，P的值可以为0.005、0.01、0.05、0.1、0.15、0.2或为其间的任意范围。不限于任何理论，本申请发明人发现，当P的值过小时(例如小于0.005)，电化学装置的高温存储性能和循环性能恶化。当P的值过大时(例如大于0.2)，电化学装置会出现较为显著的低温性能恶化。通过调控P的值在上述范围内，正极活性材料的稳定性提高，能够有效改善正极极片的锰溶出现象，而且可以满足电化学装置在循环过程中对锂的补给需求，从而有利于提高电化学装置的循环性能和高温存储性能。本申请对扣式电池的组装方法没有特别限制，可以采用本领域已知的组装方式进行组装。
在本申请的一些实施方案中，0.21-0.0056A≤P≤0.2。例如，P的值可以为0.19、0.192、0.194、0.196、0.198、0.2或为其间的任意范围。不限于任何理论，本申请发明人发现，通 过调控A和P的值满足上述关系，有利于提高电化学装置的高温循环性能。
在本申请的一些实施方案中，将前述电化学装置中的正极极片与锂金属组装为扣式电池，扣式电池在2.8V至4.6V的首圈充放电效率E为90％至110％。例如，扣式电池在2.8V至4.6V的首圈充放电效率E为90％、92％、95％、98％、100％、102％、105％、108％、110％或为其间的任意范围。
在本申请的一些实施方案中，正极活性材料的Dv50为8μm至14μm，优选为8μm至13μm，正极活性材料的Dv90小于或等于30μm，1.2≤(Dv90-Dv10)/Dv50≤2.2。
例如，正极活性材料的Dv50可以为8μm、9μm、10μm、11μm、12μm、13μm、14μm或为其间的任意范围。不限于任何理论，本申请发明人发现，当正极活性材料的Dv50过小时(例如小于8μm)，正极活性材料容易与电解液发生副反应，从而影响电化学装置的高温存储性能和循环性能。随着正极活性材料Dv50的增加，正极活性材料的与电解液之间的副反应也随之减小。但当正极活性材料的Dv50过大时(例如大于14μm)，会恶化电化学装置的低温性能。通过调控正极活性材料的Dv50在上述范围内，有利于提高电化学装置的高温存储性能、低温性能和循环性能，以及延长电化学装置的使用寿命。
例如，正极活性材料的Dv90可以为5μm、10μm、15μm、20μm、25μm、30μm或为其间的任意范围。例如，(Dv90-Dv10)/Dv50的值可以为1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9、2、2.1、2.2或为其间的任意范围。不限于任何理论，本申请发明人发现，通过调控正极活性材料的Dv50、Dv90和(Dv90-Dv10)/Dv50的值在上述范围内，有利于提高电化学装置的高温存储性能、低温性能和循环性能，以及延长电化学装置的使用寿命。本申请对正极活性材料的Dv10没有特别限制，只要能满足(Dv90-Dv10)/Dv50的范围即可，例如，正极活性材料的Dv10可以为1.0μm至17.9μm，示例性地，正极活性材料的Dv10可以为1.0μm、1.4μm、5.6μm、11.4μm、13.9μm、16.0μm、17.9μm或为其间的任意范围。
在本申请的一些实施方案中，正极活性材料包括尖晶石锰酸锂(LiMn 2O 4)以及镍钴锰酸锂、磷酸铁锂(LiFePO 4)或富锂锰基材料中的至少一种。不限于任何理论，本申请发明人发现，通过选择上述正极活性材料，有利于提高电化学装置的综合性能，例如，同时提高电化学装置的低温性能、高温存储性能和循环性能，延长电化学装置的使用寿命。
本申请对LiMn 2O 4的制备方法没有特别限制，只要能实现本申请的目的即可，例如通过碳酸锂和二氧化锰在700℃至750℃下合成得到，合成温度优选为730℃。
本申请对镍钴锰酸锂没有特别限制，只要能实现本申请的目的即可，例如可以包括但 不限于层状镍钴锰酸锂，具体地，层状镍钴锰酸锂符合通式Li(Ni x1Co y1Mn 1-x1-y1)O 2，其中，x1≥0，y1≥0，x1+y1≤1。
本申请对富锂锰基材料没有特别限制，只要能实现本申请的目的即可，例如富锂锰基材料符合通式Li 2-(x2+y2+z1)Ni x2Co y2Mn z1O 2，其中，x2≥0，y2≥0，z1﹥0，x2+y2+z1﹤1。
在本申请的一些实施方案中，正极活性材料在正极材料层中的含量为320g/m 2至480g/m 2。例如，正极活性材料在正极材料层中的含量为320g/m 22、350g/m 2、380g/m 2、400g/m 2、420g/m 2、440g/m 2、460g/m 2、480g/m 2或为其间的任意范围。不限于任何理论，本申请发明人发现，当正极活性材料在正极材料层中的含量过低时(例如低于320g/m 2)，会影响电化学装置的能量密度。当正极活性材料在正极材料层中的含量过高时(例如高于480g/m 2)，会导致部分正极活性材料难以发挥其作用，从而导致材料的浪费，影响电化学装置的成本。通过调控正极活性材料在正极材料层中的含量在上述范围内，有利于提高电化学装置的能量密度并控制其成本。
在本申请的一些实施方案中，电化学装置还包括电解液，电解液包括含有硫氧双键化合物，含有硫氧双键化合物包括1,3-丙烷磺内酯和/或硫酸乙烯酯，基于电解液的总质量，含有硫氧双键化合物的质量百分含量为0.01％至2％。例如，含有硫氧双键化合物的质量百分含量可以为0.01％、0.05％、0.1％、0.3％、0.5％、0.8％、1％、1.3％、1.5％、1.8％、2％或为其间的任意范围。不限于任何理论，电解液中包括上述含有硫氧双键的化合物且其质量百分含量在上述范围内，有利于负极形成稳定的固态电解质界面(SEI)以抑制电解液与负极活性材料之间的副反应，同时有利于正极形成稳定的正极电解液界面(CEI)以抑制正极产生相变，从而改善电化学装置的循环性能。本申请的正极可以指正极极片，负极可以指负极极片。
在本申请中，正极极片还可以包括正极集流体，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，例如可以包括但不限于铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为8μm至12μm。
在本申请中，正极材料层中还可以包括粘结剂，本申请对粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚丙烯酸、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酸锂、聚酰亚胺、聚乙烯醇、羧甲基纤维素、羧甲基纤维素钠、聚酰亚胺、聚酰胺酰亚胺、丁苯橡胶或聚偏氟乙烯中的至少一种。
在本申请中，正极材料层中还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
任选地，正极极片还可以包括导电层，导电层位于正极集流体和正极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，例如可以包括但不限于上述导电剂和上述粘结剂。
在本申请的电化学装置还可以包括负极极片，本申请中的负极极片没有特别限制，只要能实现本申请的目的即可，例如，负极极片通常包括负极集流体。其中，负极集流体没有特别限制，只要能够实现本申请目的即可，可以包括但不限于铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。在本申请中，对负极的集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为4μm至12μm。
在本申请中，负极极片还可以包括负极材料层，负极材料层包括负极活性材料。本申请对负极活性材料没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于天然石墨、人造石墨、中间相微碳球、硬碳、软碳、硅、硅-碳复合物、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的锂化TiO 2-Li 4Ti 5O 12、Li-Al合金中的至少一种。
在本申请中，负极材料层中还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于上述导电剂中的至少一种。
在本申请中，负极材料层中还可以包括粘结剂，本申请对粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于上述粘结剂中的至少一种。
任选地，负极极片还可以包括导电层，导电层位于负极集流体和负极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，导电层可以包括但不限于上述导电剂和上述粘结剂。
本申请的电化学装置还包括隔离膜，本申请对隔离膜没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯(PE)、聚丙烯(PP)、聚四氟乙烯为主的聚烯烃(PO)类隔膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚 胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜等中的至少一种。本申请的隔离膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔离膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm。
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括但不限于聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺等中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层可以包括但不限于无机颗粒和粘结剂，本申请对无机颗粒没有特别限制，例如，可以包括但不限于氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡等中的至少一种。本申请对粘结剂没有特别限制，例如，可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。聚合物层中包含聚合物，聚合物的材料可以包括但不限于聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)等中的至少一种。
在本申请中，电解液中还可以包括锂盐，本申请对锂盐没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB或二氟硼酸锂中的至少一种。优选地，锂盐包括LiPF 6。
在本申请中，电解液中还可以包括非水溶剂，本申请对锂盐非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙 酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。环状碳酸酯可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施方案中，电化学装置可以包括但不限于：锂金属二次电池、锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔离膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到电化学装置；或者，将正极极片、隔离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袋内，将电解液注入包装袋并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止电化学装置内部的压力上升、过充放电。
本申请的第二方面提供一种电子装置，包含本申请前述任一实施方案中的电化学装置。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自 行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
本申请提供一种电化学装置，其包括正极极片，正极极片包括正极材料层，正极材料层包括正极活性材料，正极活性材料中的元素包括Li、Mn、Ni、Co和Fe，其中，正极活性材料满足以下特征中的至少一种：(ⅰ)Mn的原子数与Ni、Co和Fe原子总数的比值A为3.5至40；(ⅱ)Li的原子数与Mn、Ni、Co和Fe原子总数的比值B为0.51至0.79。通过调控正极活性材料中的元素满足A和/或B的范围，通过调控正极活性材料中的元素满足A和/或B的范围，得到的电化学装置具有良好的综合性能，例如，电化学装置同时具有较长的使用寿命、良好的高温存储性能、低温性能和循环性能等。
附图说明
为了更清楚地说明本申请实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例。
图1为本申请实施例17中正极极片与锂金属组装的扣式电池的容量微分曲线。
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。基于本申请中的实施例，本领域普通技术人员所获得的所有其他技术方案，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。
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。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
元素含量的测试：
测试方法为：将锂离子电池满放至2.8V，拆解得到正极极片，将其浸泡在DMC溶液中24小时，然后干燥备用。将处理后的正极极片称重、消解、稀释，然后使用电感耦合等离子体发射光谱仪(型号为Thermo ICAP6300)测试不同元素的质量含量，每个实施例 或对比例测试6个正极极片，然后取平均值为最终结果。元素的质量百分含量＝元素的质量/正极极片的质量×100％。其中，正极极片的质量为减去正极集流体后的质量。
充电容量微分曲线的测试及P值的计算：
将锂离子电池满放至2.8V，拆解得到正极极片，将其浸泡在DMC溶液中24小时，然后干燥备用。在手套箱中将上述正极极片与锂金属组装成扣式电池，在25℃下先以0.1C的倍率进行恒流充电至4.6V，再以0.1C的倍率进行放电至2.8V(0.1C/0.1C)，其首圈充电过程中容量微分曲线在4.4V至4.6V范围的峰面积记为S1，3.9V至4.6V范围内的峰面积记为S2，P＝S1/S2。
图1示出了实施例17中的正极极片与锂金属组装得到的扣式电池的首圈充电容量微分曲线，经测量，在4.4V至4.6V范围的峰面积记S1为10.7，3.9V至4.6V范围内的峰面积记S2为100.4，计算得到P为0.11。图中的纵坐标dQ/dV是指前后两次测得的容量的差值与容量对应的电压的差值的比值。
首圈充放电效率E的测试：
将锂离子电池满放至2.8V，拆解得到正极极片，将其浸泡在DMC溶液中24小时，然后干燥备用。在手套箱中将上述正极极片与锂金属组装成扣式电池，在25℃下先以0.1C的倍率进行恒流充电至4.6V，然后恒压充电至50μA，再以0.1C的倍率进行放电至2.8V(0.1C/0.1C)，首圈效率E＝放电截至电压为2.8V的容量/充电电压截至到4.6V对应的容量。
克容量的测试：
在约25℃的环境中，将锂离子电池以0.5C(即，2小时内完全放掉理论容量的电流值)的充电电流下进行恒流和恒压充电，直到上限电压约为4.2V，然后在0.2C的放电电流下进行恒流放电，直到最终电压约为2.8V，记录首次放电容量。首次放电容量与正极极片的质量的比值记为正极极片的克容量。每个实施例或对比例测试4个正极极片，取平均值为最终结果。其中，正极极片的质量为减去正极集流体后的质量。
高温循环性能的测试：
测试待测锂离子电池的厚度，记为初始厚度。在约45℃的环境中，将锂离子电池在0.5C的充电电流下进行恒流和恒压充电，直到上限电压约为4.2V，然后在1C的放电电流下进行恒流放电，直到最终电压约为2.8V，记录首次循环的放电容量为初始放电容量。然后以相同的步骤进行500次的充电和放电循环，记录500次循环后锂离子电池的放电容量为循环放电容量，并测试500次循环后的锂离子电池的厚度记为循环厚度。
通过下式计算锂离子电池在45℃下的循环容量保持率：
45℃500圈循环容量保持率＝(循环放电容量/初始放电容量)×100％。
通过下式计算锂离子电池在45℃下的循环膨胀率：
45℃500圈循环膨胀率＝(循环厚度-初始厚度)/初始厚度×100％
每个实施例或对比例测试4个锂离子电池，取平均值为最终测试结果。
高温存储性能的测试：
将锂离子电池在25℃的环境中静置30分钟，然后以0.2C倍率恒流充电至4.2V，再以4.2V恒压充电至0.05C，静置30分钟，然后以0.5C倍率放电至2.8V，记录此时的放电容量为锂离子电池存储前容量；然后将满充状态的电池置于约60℃烘箱存储约7天后，测试其存储后容量。具体测试流程如下：将锂离子电池在25℃的环境中静置30分钟，然后以0.2C倍率恒流充电至4.2V，以4.2V恒压充电至0.05C，静置30分钟，然后以0.5C倍率放电至2.8V，记录此时的放电容量为锂离子电池的存储后容量。
通过下式计算锂离子电池在60℃下的高温存储容量保持率：
60℃高温存储容量保持率＝存储后容量/存储前容量×100％。
每个实施例或对比例测试4个锂离子电池，取平均值为最终结果。
低温性能的测试：
将锂离子电池在25℃的环境中静置30分钟，然后以0.2C倍率恒流充电至4.2V，以4.2V恒压充电至0.05C，静置30分钟，接着以0.5C倍率放电至2.8V，记录此时的放电容量为锂离子电池的实际容量C1；然后将锂离子电池在-10℃的环境中静置60分钟后再以0.2C倍率恒流充电至4.2V，以4.2V恒压充电至0.05C，静置30分钟，接着以0.5C倍率放电至2.8V，记录此时的放电容量为锂离子电池的实际容量C2。-10℃低温放电容量保持率＝C2/C1×100％。
实施例1
<正极极片的制备>
将尖晶石锰酸锂LiMn 2O 4和层状镍钴锰酸锂Li(Ni 0.55Co 0.15Mn 0.30)O 2按照质量比为67∶33进行混合得到正极活性材料，然后将正极活性材料、导电剂乙炔黑、粘结剂聚偏二氟乙烯按照质量比为96.5∶2∶1.5进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌至体系成均一透明状，获得正极浆料，其中正极浆料的固含量为70％。将正极浆料均匀涂覆于厚度为12μm的正极集流体铝箔的一个表面上，将铝箔在120℃下烘干处理1h，得到单面涂覆有正极材料层的正极极片，正极活性材料在正极材料层中的含量为425g/m 2。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极活性材料的正极极片。 然后经过冷压、裁片、分切后，在120℃的真空条件下干燥1h，得到规格为(74mm×867mm)的正极极片。其中，LiMn 2O 4通过碳酸锂和二氧化锰在730℃下合成得到，碳酸锂和二氧化锰的质量比为0.55，正极活性材料的Dv50为11μm，Dv90为19μm。
<负极极片的制备>
将负极活性材料人造石墨、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC)按照质量比为95∶2∶2∶1进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料，其中负极浆料的固含量为75％。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，将铜箔在120℃下烘干，得到单面涂覆有负极材料层的负极极片，负极活性材料在正负极材料层中的含量为112g/m 2。在铝箔的另一个表面上重复以上步骤，即得到双面涂布负极活性材料的负极极片。然后经过冷压、裁片、分切后，在120℃的真空条件下干燥1h，得到规格为(76mm×869mm)的负极极片。
<电解液的制备>
在干燥的氩气气氛手套箱中，将有机溶剂碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二乙酯(DEC)按照质量比为1∶1∶1混合，然后向有机溶剂中加入锂盐六氟磷酸锂(LiPF 6)溶解并混合均匀，得到电解液。其中，LiPF 6在电解液中的浓度为1.15mol/L。
<隔离膜的制备>
采用厚度为7μm的多孔聚乙烯(PE)薄膜(Celgard公司提供)，孔径为0.1μm。
<锂离子电池的制备>
将上述制备得到的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间已起到隔离的作用，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。
实施例2至实施例11中，除了按照表1调整正极活性材料的种类及其质量比以外，其余与实施例1相同。
实施例12至实施例15中，除了依次调整碳酸锂和二氧化锰的质量比为0.5、0.55、0.57、0.59使B值如表1所示、按照表1调整正极活性材料的种类及其质量比以外，其余与实施例1相同。
实施例16至实施例19中，除了按照表2调整正极活性材料的种类及其质量比使得P值如表2所示以外，其余与实施例13相同。
实施例20至实施例23中，除了按照表3调整正极活性材料在正极材料层的中的含量 和负极活性材料在负极材料层的中的含量以外，其余与实施例13相同。
实施例24至实施例28中，除了按照表4调整正极活性材料的粒径以外，其余与实施例13相同。
对比例1中，除了按照表1调整正极活性材料的种类及其质量比以外，其余与实施例1相同。
对比例2和对比例3中，除了按照表2调整正极活性材料的种类及其质量比以外，其余与实施例13相同。
对比例4和对比例5中，除了按照表3调整正极活性材料在正极材料层的中的含量和负极活性材料在负极材料层的中的含量以外，其余与实施例13相同。
对比例6中，除了按照表4调整正极活性材料的粒径以外，其余与实施例13相同。
表1
Figure PCTCN2021118515-appb-000001
Figure PCTCN2021118515-appb-000002
注：表1中的“/”表示不存在该参数或物质。
表2
Figure PCTCN2021118515-appb-000003
Figure PCTCN2021118515-appb-000004
表3
Figure PCTCN2021118515-appb-000005
表4
Figure PCTCN2021118515-appb-000006
参考表1，从实施例1至实施例15、对比例1可以看出，当正极活性材料A和/或B的值在本申请的范围内，能够提高电化学装置的综合性能，例如电化学装置同时具有良好的低温性能、高温存储性能和高温循环性能，扣式电池的首圈充放电效率明显提高。
从实施例12至实施例15可以看出，当A的值不变，随着B的值增大，正极极片的比容量呈现下降的趋势，高温存储性能和高温循环性能呈现逐渐好转的趋势。
参考表2，从实施例13、实施例16至实施例19、对比例2和对比例3可以看出，当P值在本申请的范围内时，能够提高电化学装置的综合性能，例如电化学装置同时具有良好的低温性能、高温存储性能和高温循环性能。
正极活性材料在正极材料层中的含量通常会影响电化学装置的综合性能，参考表3，从实施例13、实施例20至实施例23、对比例4和对比例5可以看出，当正极活性材料在正极材料层中含量在本申请的范围内时，得到的电化学装置具有良好的综合性能，例如电化学装置同时具有良好的低温性能、高温存储性能和高温循环性能。
正极活性材料的粒径及粒径之间的关系通常会影响电化学装置的综合性能，参考表4，从实施例13、实施例24至实施例28、对比例6可以看出，当正极活性材料的Dv50、Dv90以及Dv90-Dv10)/Dv50的值同时在本申请的范围内时，得到的电化学装置具有良好的综合性能，例如电化学装置同时具有良好的低温性能、高温存储性能和高温循环性能。
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 (10)

  1. 一种电化学装置，其包括正极极片，所述正极极片包括正极材料层，所述正极材料层包括正极活性材料，所述正极活性材料中的元素包括Li、Mn、Ni、Co和Fe，其中，所述正极活性材料满足以下特征中的至少一种：
    (ⅰ)Mn的原子数与Ni、Co和Fe原子总数的比值A为3.5至40；
    (ⅱ)Li的原子数与Mn、Ni、Co和Fe原子总数的比值B为0.51至0.79。
  2. 根据权利要求1所述的电化学装置，其中，6≤A/B≤40。
  3. 根据权利要求1所述的电化学装置，将所述电化学装置中的正极极片与锂金属组装为扣式电池，在所述扣式电池的首圈充电容量微分曲线中，在4.4V至4.6V之间峰的面积与3.9V至4.6V之间峰的面积的比值P为0.005至0.2。
  4. 根据权利要求3所述的电化学装置，其中，0.210.0056A≤P≤0.2。
  5. 根据权利要求1所述的电化学装置，将所述电化学装置中的正极极片与锂金属组装为扣式电池，所述扣式电池在2.8V至4.6V的首圈充放电效率E为90％至110％。
  6. 根据权利要求1所述的电化学装置，其中，所述正极活性材料的Dv50为8μm至14μm，所述正极活性材料的Dv90小于或等于30μm，1.2≤(Dv90-Dv10)/Dv50≤2.2。
  7. 根据权利要求1所述的电化学装置，其中，所述正极活性材料包括尖晶石锰酸锂以及镍钴锰酸锂、磷酸铁锂或富锂锰基材料中的至少一种。
  8. 根据权利要求1所述的电化学装置，其中，所述正极活性材料在所述正极材料层中的含量为320g/m 2至480g/m 2。
  9. 根据权利要求1所述的电化学装置，其还包括电解液，所述电解液包括含有硫氧双键化合物，所述含有硫氧双键化合物包括1,3-丙烷磺内酯和/或硫酸乙烯酯，基于所述电解液的总质量，所述含有硫氧双键化合物的质量百分含量为0.01％至2％。
  10. 一种电子装置，其包括权利要求1至9中任一项所述的电化学装置。
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