WO2023108481A1 - 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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WO2023108481A1
WO2023108481A1 PCT/CN2021/138349 CN2021138349W WO2023108481A1 WO 2023108481 A1 WO2023108481 A1 WO 2023108481A1 CN 2021138349 W CN2021138349 W CN 2021138349W WO 2023108481 A1 WO2023108481 A1 WO 2023108481A1
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positive electrode
active material
electrochemical device
carbonate
electrode active
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PCT/CN2021/138349
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English (en)
French (fr)
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袁国霞
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宁德新能源科技有限公司
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Priority to PCT/CN2021/138349 priority Critical patent/WO2023108481A1/zh
Priority to KR1020237013888A priority patent/KR20230093433A/ko
Priority to JP2023518462A priority patent/JP2024502522A/ja
Priority to CN202180046458.9A priority patent/CN115956306A/zh
Publication of WO2023108481A1 publication Critical patent/WO2023108481A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
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    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
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    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
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    • 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
    • H01M4/485—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
    • 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
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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

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. potential new green chemical power sources. However, with the widespread application of lithium-ion batteries, the market puts forward higher requirements for the comprehensive performance of lithium-ion batteries.
  • the positive electrode active material, negative electrode active material and electrolyte in lithium-ion batteries are important parameters that affect the performance of lithium-ion batteries. Among them, the selection of positive electrode active materials will affect the transport efficiency of lithium ions, thereby affecting the electrochemical performance of electrochemical devices, such as rate performance. However, the existing cathode active materials need to be further optimized to improve the rate performance of electrochemical devices.
  • the purpose of this application is to provide an electrochemical device and an electronic device to improve the rate performance of the electrochemical device at low temperature and normal temperature.
  • 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 in the scanning electron microscope photo of the cross section of the positive electrode material layer, the area is greater than 5 ⁇ m 2.
  • the radius of the smallest circumscribed circle of the outline of positive electrode active material particles is R c
  • the radius of the largest inscribed circle of the outline of positive electrode active material particles with an area larger than 5 ⁇ m is R i , satisfying the average value of 1 ⁇ R c /R i Value ⁇ 3.
  • the average value of R c /R i may be 1.1, 1.5, 1.8, 2, 2.3, 2.5, 2.8, 3 or any range therebetween.
  • the electrochemical device provided by the present application wherein the positive electrode active material in the positive electrode material layer satisfies 1 ⁇ the average value of R c / R i ⁇ 3, can effectively improve the transmission efficiency of lithium ions in the process of charging and discharging , thereby improving the rate performance of the electrochemical device at room temperature and low temperature (for example, the temperature is less than or equal to 0°C).
  • room temperature and low temperature for example, the temperature is less than or equal to 0°C.
  • the average value of R c /R i is in the positive electrode material layer in the above range, and its morphology can enable the positive electrode active material to maintain a stable crystal structure in a cycle of a larger rate, and effectively improve the performance of the positive electrode active material.
  • the cross section of the positive electrode material layer refers to a cross section along the thickness direction of the positive electrode material layer.
  • the positive electrode active material particles with an area greater than 5 ⁇ m 2 include first particles and second particles, the radius of the smallest circumscribed circle of the outline of the first particle is R c1 , and the largest inner circle of the outline of the first particle is The radius of the tangent circle is R i1 , which satisfies the average value of 1 ⁇ R c1 /R i1 ⁇ 1.5 ; the radius of the smallest circumscribed circle of the outline of the second particle is R c2 , and the radius of the largest inscribed circle of the outline of the second particle is R i2 satisfies the average value of 1.5 ⁇ R c2 /R i2 ⁇ 3 .
  • the area percentage of the first particles is greater than 0% and less than or equal to 50%, and the area percentage B of the second particles is 30% to 80%.
  • the average value of R c1 /R i1 can be 1.1, 1.2, 1.3, 1.4, 1.5 or any range therebetween; the average value of R c2 /R i2 can be 1.6, 2, 2.5, 3 or any range therebetween Range;
  • the area percentage of the first particle can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any range therebetween;
  • the area percentage B of the two particles can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any range therebetween.
  • the first particles and the second particles are distributed in the positive electrode material layer in the above ratio.
  • the staggered distribution between particles with different R c /R i values in the positive electrode material layer is realized, which improves the positive electrode active material and the conductive agent.
  • Distributed network so as to effectively reduce the interface side reaction in the positive electrode material layer, improve the lithium ion transmission efficiency and the internal electronic conductivity of the positive electrode sheet, and realize the effective improvement of the rate performance and cycle performance of the electrochemical device.
  • the area percentage B of the second particle refers to the compacted density of the positive electrode material layer in the positive electrode sheet.
  • the average cross-sectional area of the first particles is smaller than the average cross-sectional area of the second particles, which is beneficial to reduce the lithium ion transport path and improve the rate performance of the electrochemical device.
  • the electrochemical device satisfies at least one of the conditions (a) to (b): (a) the positive electrode active material includes lithium manganate; lithium manganate includes doped lithium manganate and/or Contains coated lithium manganate.
  • the present application has no special restrictions on the doping elements in the doped lithium manganese oxide, as long as the purpose of the application can be achieved, for example, the doping elements may include but are not limited to Al, Nb, Mg, Ti, F, B, Zr, At least one of W, Sr, Y, Ce or La.
  • the present application has no special restrictions on the elements in the cladding layer in the lithium manganese oxide containing the cladding layer, as long as the purpose of the application can be achieved, for example, the elements in the cladding layer can include but are not limited to Al, Sr, Zr , Ti or B at least one.
  • the positive electrode active material includes a composite metal oxide of lithium and a transition metal element, the transition metal element includes Mn and a metal element M1, and the metal element M1 includes at least one of Ni, Co or Fe. Based on the mass of the positive electrode active material, the mass percentage of Mn is 30% to 65%, and the mass percentage of the metal element M1 is 2% to 25%.
  • the electrochemical device satisfies at least one of the conditions (a) to (b), which is conducive to improving the cycle performance and low-temperature rate performance of the electrochemical device.
  • the second particle includes a metal element M2, and the metal element M2 includes at least one of Al, Mg, or Nb.
  • the mass percentage of the metal element M2 is 0.1% to 3%.
  • the mass percentage of metal element M2 can be 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.5%, 3%, or any range therebetween .
  • positive electrode active materials containing manganese are widely used in electrochemical devices, such as lithium ion batteries.
  • the Mn 3+ present in lithium manganese oxide is prone to disproportionation reaction, which leads to the dissolution of manganese (Mn 2+ ), and then migrates to the negative electrode through the electrolyte, destroying the solid electrolyte interface (SEI) film of the negative electrode, and repairing the SEI film will cause
  • SEI solid electrolyte interface
  • the negative electrode may refer to a negative electrode sheet.
  • the inventors of the present application have found that for an electrochemical device including a positive electrode active material containing manganese, when the positive electrode active material includes the metal element M1, by selecting the above metal element M1, it is beneficial to improve the manganese dissolution phenomenon, thereby reducing the impact on the SEI film of the negative electrode. Damage, and repair the loss of active lithium caused by the consumption of lithium in the SEI film, thereby improving the cycle performance and rate performance of the electrochemical device.
  • the inventors of the present application have found that when the second particle includes the metal element M2, by selecting the above metal element M2, the side reaction at the interface between the second particle and the electrolyte solution during the low-temperature charging and discharging process can be reduced, thereby improving the internal resistance of the positive electrode sheet and improving Low-temperature rate performance of electrochemical devices.
  • the inventors of the present application found that when the mass percentage of the metal element M2 is too low (for example, less than 0.1%), the side reaction between the second particles and the electrolyte is not significantly improved. When the mass percentage of the metal element M2 is too high (for example, higher than 3%), the side reaction between the second particles and the electrolyte cannot be further improved, and the gram capacity of the positive electrode active material will be reduced. By adjusting the mass percentage of the metal element M2 within the above range, it is beneficial to reduce the interface side reaction between the second particle and the electrolyte, and improve the cycle performance of the electrochemical device.
  • the negative electrode may refer to a negative electrode sheet.
  • the volume particle size distribution of the positive electrode active material satisfies at least one of the conditions (c) to (d): (c) 9 ⁇ m ⁇ Dv50 ⁇ 22 ⁇ m; (d) 0.9 ⁇ (Dv90-Dv10) /Dv50 ⁇ 2.
  • the Dv50 of the positive electrode active material can be 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, 21 ⁇ m, 22 ⁇ m or any range therebetween.
  • the value of (Dv90-Dv10)/Dv50 can be 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or any range therebetween. Satisfying at least one of the conditions (c) to (d) by adjusting the volume particle size distribution of the positive electrode active material is conducive to improving the rate performance of the electrochemical device at room temperature and low temperature.
  • the present application has no special restrictions on Dv90 and Dv10 of the positive electrode active material, as long as the value of (Dv90-Dv10)/Dv50 is within the above range, for example, the Dv90 of the positive electrode active material is 15 ⁇ m to 40 ⁇ m, and the Dv10 of the positive electrode active material is 0.5 ⁇ m to 6 ⁇ m.
  • the value of (Dv90-Dv10)/Dv50 mainly reflects the particle size distribution of the positive electrode active material.
  • the electrochemical device further includes an electrolyte
  • the electrolyte includes chain carbonates and cyclic carbonates, based on the mass of the electrolyte, the mass percentage of the chain carbonates is ⁇ 1 , and the ring
  • the mass percentage content ⁇ 2 of the carbonic acid ester is 25% to 50%, and the ⁇ 1 / ⁇ 2 is 0.75 to 2.5.
  • the mass percentage content ⁇ of cyclic carbonate can be 25%, 30%, 35%, 40%, 45%, 50% or be any range therebetween;
  • the value of ⁇ 1 / ⁇ 2 can be 0.75, 1, 1.25, 1.5, 1.75, 2, 2.25, 2.5 or any range in between.
  • the electrolyte while regulating the average value of R c /R i in the positive electrode active material, the electrolyte includes chain carbonates and cyclic carbonates, so that there is a synergy between the positive electrode active material and the electrolyte, which can improve The transmission path of lithium ions, especially the improvement of the lithium ion transmission efficiency at the interface between the positive electrode active material and the electrolyte, thereby improving the rate performance of the electrochemical device.
  • cyclic carbonate when the mass percent content ⁇ of cyclic carbonate is too low (such as being lower than 25%), cyclic carbonate can not form good synergism with chain carbonate to improve lithium ion Transmission efficiency; when the mass percentage of cyclic carbonate ⁇ 2 is too high (for example, higher than 50%), the viscosity of the electrolyte is increased, which is not conducive to the transmission of lithium ions, thereby affecting the rate performance of the electrochemical device. When the value of ⁇ 1 / ⁇ 2 is less than 0.75 or greater than 2.5, it will affect the synergistic effect between cyclic carbonate and chain carbonate, thereby affecting the transmission efficiency of lithium ions.
  • the positive electrode active material can be fully infiltrated, thereby increasing lithium ions at the interface of the positive electrode active material and electrolyte transfer efficiency, and thus improve the rate performance of the electrochemical device.
  • the mass percentage of chain carbonate is ⁇ 1 can be 35%, 40%, 45%, 50%, 55%, 60%, 65% or any range therebetween.
  • regulating the mass percentage of chain carbonates ⁇ 1 is within the scope of the application, it is beneficial to form a good synergy between cyclic carbonates and chain carbonates, and improve the transmission efficiency of lithium ions , thereby improving the rate performance of the electrochemical device.
  • chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene propyl carbonate (EPC), dipropyl carbonate (DPC), methyl isopropyl carbonate, methyl butyl carbonate or dibutyl carbonate (DBC).
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • EPC ethylene propyl carbonate
  • DPC dipropyl carbonate
  • methyl isopropyl carbonate methyl butyl carbonate or dibutyl carbonate
  • the cyclic carbonate includes at least one of ethylene carbonate (EC), propylene carbonate (PC) or butylene carbonate (BC).
  • EC ethylene carbonate
  • PC propylene carbonate
  • BC butylene carbonate
  • the electrolyte includes a sulfonate compound, and based on the mass of the electrolyte, the mass percentage of the sulfonate compound is A, satisfying 0.006 ⁇ A/B ⁇ 0.1.
  • the value of A/B may be 0.006, 0.008, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1 or any range therebetween.
  • the sulfur-oxygen double bond in the sulfonate compound is beneficial to improve the stability of the SEI film and reduce the deposition of dissolved manganese on the negative electrode, thereby improving the cycle performance of the electrochemical device.
  • the mass percentage content A of sulfonate compound can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or between any range.
  • the mass percentage content A of sulfonate compound is too low (such as being lower than 0.5%), the improvement of SEI membrane stability is not obvious;
  • the mass percentage content A of sulfonate compound is too high
  • it is higher than 10% for example, an overly thick or overly dense SEI film will be formed, hindering the transport of lithium ions, resulting in a decrease in the rate performance of the electrochemical device.
  • the sulfonate compound includes at least one of the following structural compounds I-1 to I-14.
  • the sulfonate compound with the following structure, it is beneficial to improve the stability of the SEI film and reduce the deposition of leached manganese on the negative electrode, thereby improving the cycle performance of the electrochemical device.
  • the electrochemical device also includes a negative electrode sheet, the negative electrode sheet includes a negative electrode material layer, the negative electrode material layer includes a negative electrode active material, and the negative electrode active material includes at least one of artificial graphite, natural graphite or hard carbon kind.
  • the negative electrode active material includes at least one of artificial graphite, natural graphite or hard carbon kind.
  • the positive electrode active material may include, but is not limited to, at least one of composite oxides and/or sulfides, selenides, or halides of the composite oxides.
  • an amorphous compound or a crystalline compound may also exist on the surface of the composite oxide, and the amorphous or crystalline compound may include but not limited to an oxide of element Z, a hydroxide of element Z, an oxyhydroxide of element Z , at least one of an oxycarbonate of element Z or a hydroxycarbonate of element Z.
  • the element Z may include but not limited to at least one of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As or Zr.
  • the present application has no special limitation on the preparation method of the composite oxide containing amorphous compound or crystalline compound on the surface, as long as the purpose of the present application can be achieved, such as spraying method or dipping method.
  • 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, Ketjen black, graphene, metal material or conductive polymer, the above-mentioned carbon nanotubes may include but 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-mentioned 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. In the present application, based on the mass of the positive electrode material layer, the mass percentage of the conductive agent is 0.5% to 5%.
  • the positive electrode material layer may also include a positive electrode binder.
  • This application has no special restrictions on the positive electrode binder, as long as the purpose of this application can be achieved, for example, it may include but not limited to polyvinyl alcohol, carboxymethyl Cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, At least one of polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester)ized styrene-butadiene rubber, epoxy resin or nylon.
  • the positive pole piece includes a positive current collector.
  • the positive electrode current collector is not particularly limited, as long as the purpose of the present application can be achieved, for example, it may include but not limited to aluminum foil, aluminum alloy foil or composite current collector.
  • the thickness of the positive electrode collector there is no particular limitation on the thickness of the positive electrode collector, as long as the purpose of the present application can be achieved, for example, the thickness is 8 ⁇ m to 20 ⁇ m.
  • 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 positive electrode binder.
  • 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 negative electrode binder, and the present application has no special restrictions on the negative electrode binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to ethylene difluoride-hexafluoropropylene Copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride , polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester)-based styrene-butadiene rubber, epoxy resin or nylon kind.
  • ethylene difluoride-hexafluoropropylene Copolymer polyvinylidene fluoride,
  • the negative electrode sheet includes a negative electrode current collector.
  • the negative electrode current collector is not particularly limited, as long as the purpose of this application can be achieved, for example, 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 wait.
  • the thickness of the current collector of the negative electrode is 4 ⁇ m to 12 ⁇ m.
  • the negative electrode sheet may further include a conductive layer 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 negative electrode binder.
  • non-aqueous solvents may also be included in the electrolyte, and the present application has no special restrictions on non-aqueous solvents, as long as the purpose of the application can be achieved, for example, it may include but not limited to carboxylate compounds, ether compounds or other at least one of organic solvents.
  • carboxylate compounds may include but are not limited to methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, butyric acid Methyl ester, ethyl butyrate, propyl butyrate, butyl butyrate, ⁇ -butyrolactone, 2,2-difluoroethyl acetate, valerolactone, butyrolactone, ethyl 2-fluoroacetate, 2 ,Ethyl 2-difluoroacetate, ethyl trifluoroacetate, ethyl 2,2,3,3,3-pentafluoropropionate, 2,2,3,3,4,4,4,4-heptafluoro Methyl butyrate, methyl 4,4,4-trifluoro-3-(trifluoromethyl)
  • the aforementioned ether compounds may include, but are not limited to, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, or bis(2,2,2 - at least one of trifluoroethyl) ethers.
  • the above-mentioned other organic solvents may include but not limited to ethyl vinyl sulfone, methyl isopropyl sulfone, isopropyl sec-butyl sulfone, dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-Dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, or phosphoric acid at least one of esters.
  • lithium salts may also be included in the electrolytic solution.
  • the present application has no particular limitation on lithium salts, as long as the purpose of the present application can be achieved, for example, it may include but not limited to lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate ( LiBF 4 ), lithium bisoxalate borate (LiB(C 2 O 4 ) 2 ), lithium difluorooxalate borate (LiBF 2 (C 2 O 4 )), lithium hexafluoroantimonate (LiSbF 6 ), perfluorobutylsulfonate Lithium oxide (LiC 4 F 9 SO 3 ), lithium perchlorate (LiClO 4 ), lithium aluminate (LiAlO 2 ), lithium tetrachloroaluminate (LiAlCl 4 ), lithium bissulfonylimide (LiN(C x F 2x+1 SO 2 ) (
  • the lithium salt comprises LiPF 6 .
  • the present application has no special limitation on the concentration of the lithium salt, as long as the purpose of the present application can be achieved, for example, the concentration is 0.5mol/L to 3mol/L, preferably 0.5mol/L to 2mol/L, more preferably 0.6mol/L L to 1.5mol/L.
  • 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)-based release film, 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)-based release film, polyester film (such as polyethylene terephthalate (PET) 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.
  • the separator may include a separator base layer and a surface treatment layer.
  • the isolation film substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the isolation film substrate layer can include but not limited to polyethylene, polypropylene, polyethylene terephthalate or polyamide At least one of imine and the like.
  • 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 base material layer of the isolation film 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 polymer layer contains a polymer
  • the polymer material may include but not limited to vinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyimide, acrylonitrile-butadiene copolymer, propylene Nitrile-styrene-butadiene copolymer, polymethylmethacrylate, polymethylacrylate, polyethylacrylate, acrylic-styrene copolymer, polydimethylsiloxane, sodium polyacrylate or carboxymethyl at least one of cellulose.
  • Inorganic layer may include but not limited to inorganic particles and inorganic layer binder, the application has no particular limitation on inorganic particles, for example, may include but not limited to ceramics, alumina, silicon oxide, magnesium oxide, titanium oxide, dioxide At least one of hafnium, tin oxide, cerium oxide, nickel oxide, zinc oxide, calcium oxide, zirconia, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate kind.
  • the present application has no special limitation on the inorganic layer binder, for example, it may include but not limited to polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, poly At least one of acrylate, polyvinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • 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 into the packaging bag and seal it, and 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.
  • a second aspect of the present application provides an electronic device, comprising the electrochemical device in any embodiment of the present application.
  • the electrochemical device provided by the application has good rate performance and cycle performance, so the electronic device provided by the application has a long service life.
  • the electronic device of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • the application provides an electrochemical device, which includes a positive electrode sheet, the positive electrode sheet includes a positive electrode material layer, and the positive electrode material layer includes a positive electrode active material.
  • the cross section The radius of the smallest circumscribed circle of the outline of positive electrode active material particles with an area greater than 5 ⁇ m 2 is R c , the radius of the largest inscribed circle of the outline of particles with a cross-sectional area greater than 5 ⁇ m 2 is R i , satisfying 1 ⁇ R c /R i The average value of ⁇ 3.
  • the positive electrode active material in the positive electrode material layer satisfies the average value of 1 ⁇ R c /R i ⁇ 3, which can effectively improve the lithium ion transmission efficiency of the positive electrode sheet, thereby improving the electrochemical device in the electrochemical device. Rate performance at room temperature and low temperature.
  • Fig. 1 is the scanning electron micrograph of the positive electrode material layer section in an embodiment of the present application
  • FIG. 2 is a schematic cross-sectional view of a positive pole piece in an embodiment of the present application.
  • Reference numerals 10, positive electrode current collector, 20, positive electrode material layer, 21, positive electrode active material.
  • FIG. 1 shows a scanning electron micrograph of a cross-section of the positive electrode material layer in an embodiment of the present application. It can be seen from the figure that there are differences in the size and shape of the particles of the positive electrode active material 21 .
  • the smallest circumscribed circle of the outline of particle C is R1, the largest inscribed circle of the outline of particle C is R2; the smallest circumscribed circle of the outline of particle D is R3, and the largest inscribed circle of the outline of particle D is R4.
  • particle C is an example of the first particle in the present application
  • particle D is an example of the second particle in the present application.
  • Fig. 2 shows a schematic cross-sectional view of a positive electrode sheet in an embodiment of the present application.
  • the cross-section of the aforesaid positive electrode material layer in this application refers to the cross-section along the direction of the arrow in the figure.
  • the average value of R c1 /R i1 of the first particle and the average value of R c2 /R i2 of the second particle can be obtained by controlling the minimum circumscribed circle of the particle outline of the raw material
  • the ratio of the radius to the radius of the largest inscribed circle, as well as the Dv50 of the raw material, are controlled by comprehensively adjusting the stirring speed or calcination temperature during the preparation of the positive electrode active material.
  • 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 above-mentioned SEM images were identified by the software Image J, and 100 particles whose cross-sections were completely within the image field of view and whose cross-sectional area was larger than 5 ⁇ m2 were randomly selected, and the radius R i and the minimum radius R i of the largest inscribed circle of the particles were respectively calculated by using an algorithm.
  • the radius R c of the circumscribed circle is calculated (refer to "Kenneth C.Williams, Wei Chen, Sebastian Weeger, Timothy J.Donohue, Particle shape characterization and its application to discrete element modeling, Particuology, Volume 12, 2014, Pages 80-89, ISSN 1674-2001").
  • R c1 , R i1 , R c2 , and R i2 are the same as those of R i and R c .
  • the measurement of R c3 and R i3 is that manganese dioxide is first prepared into slurry and then coated on the base material to form a film layer, and is measured with reference to the measurement method of R i and R c , wherein the solid content of slurry (such as 75 wt%) and the type of substrate are not particularly limited as long as the purpose of the present application can be achieved.
  • the measurement of R c4 and R i4 , R c5 and R i5 refers to the measurement method of R c3 and R i3 .
  • the area percentage is the first grain area/image area ⁇ 100%
  • the second grain area percentage is the second grain area/image area ⁇ 100%.
  • the Malvern particle size tester to measure the particle size of the positive electrode active material, disperse the positive electrode active material in ethanol, add it into the Malvern particle size tester after ultrasonication for 30 minutes, and start the test.
  • the particle size reaching 10% of the volume accumulation is the Dv10 of the positive electrode active material
  • the particle size reaching 50% of the volume accumulation is the Dv50 of the positive electrode active material.
  • the particle size reaching 90% of the cumulative volume is the Dv90 of the positive electrode active material.
  • EDS energy spectrometer
  • Scrape off the positive electrode material layer of the positive electrode sheet cleaned with DMC, and dissolve it with a mixed solvent for example, 0.4g of positive electrode active material uses 10ml of aqua regia (nitric acid and hydrochloric acid are mixed according to the volume ratio of 1:1) and 2ml of HF Mixed solvent), set the volume to 100mL, and then use an inductively coupled plasma (ICP) analyzer to test the content of elements in the solution.
  • a mixed solvent for example, 0.4g of positive electrode active material uses 10ml of aqua regia (nitric acid and hydrochloric acid are mixed according to the volume ratio of 1:1) and 2ml of HF Mixed solvent
  • Compacted density P m/[25 ⁇ (d0-d)], unit g/cm 3 .
  • the compacted density of the positive electrode material layer is the average value of the compacted density of the positive electrode material layer in the five positive electrode sheets obtained by cutting.
  • Dv90 refers to the particle diameter that reaches 90% of the volume accumulation from the small particle size side in the volume-based particle size distribution
  • Dv50 refers to the volume accumulation of 50% from the small particle size side in the volume-based particle size distribution
  • the particle diameter of Dv10 refers to the particle diameter from the small particle diameter side to reach 10% of volume accumulation in the volume-based particle size distribution.
  • the lithium-ion battery was subjected to the cycle process of "0.5C charge-2C discharge" for several times, and the cycle was 1000 cycles, and the discharge capacity after the 1000th cycle was tested to be D 10 .
  • Capacity retention (%) after 1000 cycles at 25°C D 10 /D 01 ⁇ 100%.
  • Disassemble the lithium-ion battery in a fully charged state after 500 cycles at 40°C take the negative electrode sheet and wash it with DMC, then dry it at 60°C for 2 hours, and then scrape off the negative electrode material layer of the negative electrode sheet with a scraper.
  • Dissolve in a mixed solvent for example, use 10ml of aqua regia for 0.4g of negative electrode active material (mixture of nitric acid and hydrochloric acid at a volume ratio of 1:1)
  • set the volume to 100ml and then use an ICP analyzer to test the content of manganese in the solution.
  • Negative electrode active material artificial graphite, conductive agent Super P, thickener sodium carboxymethylcellulose (CMC), binder styrene-butadiene rubber (SBR) are mixed according to the mass ratio of 96.4:1.5:0.5:1.6, 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 70wt%. Apply the negative electrode slurry evenly on one surface of the negative electrode current collector copper foil with a thickness of 10 ⁇ m, and dry the copper foil at 85° C. to obtain a negative electrode with a coating thickness of 130 ⁇ m coated with a negative electrode material layer on one side piece.
  • CMC thickener sodium carboxymethylcellulose
  • SBR binder styrene-butadiene rubber
  • Water-based polyvinylidene fluoride, aluminum oxide, and polypropylene were mixed in a mass ratio of 1:8:1, added to deionized water, and stirred to obtain a coating slurry with a solid content of 50 wt%.
  • the coating slurry was uniformly coated on one surface of a PE film (provided by Celgard) with a thickness of 5 ⁇ m, and dried at 85° C. to obtain a single-side coated isolation film with a coating thickness of 5 ⁇ m. Repeat the above steps on the other surface of the isolation film to obtain a double-sided coated isolation film. Then, it is dried and cold-pressed to obtain the isolation film.
  • the porosity of the separator is 39%.
  • the electrode assembly is obtained by winding.
  • the electrode assembly in an aluminum-plastic film packaging bag, inject electrolyte after drying, and obtain a lithium-ion battery through processes such as vacuum packaging, standing, chemical formation, degassing, and edge trimming.
  • the formation condition is to charge to 3.3V with a constant current of 0.02C, and then charge to 3.6V with a constant current of 0.1C.
  • R c4 is the radius of the smallest circumscribed circle of the contour of the trimanganese tetraoxide particle
  • R i4 is the radius of the largest inscribed circle of the contour of the trimanganese tetraoxide particle.
  • the positive active material LMO the positive active material LiNi 0.55 Co 0.15 Mn 0.3 O 2 (NCM5515), the conductive agent Super P, and the binder polyvinylidene fluoride are used according to the mass ratio of 76.8 : 19.2: 2.4: 1.6 mix, add NMP, stir until system becomes homogeneous under the effect of vacuum mixer, obtain the positive electrode slurry that solid content is 75wt%, and adjust the average value of R c3 /R i3 of manganese dioxide and The Dv50 makes the average value of R c /R i of the second particle and the Dv50 of the positive electrode active material as shown in Table 2, and the rest is the same as that of Example 1-1.
  • NCM5515 is prepared by the following method: Lithium carbonate (wherein the lithium element mass percentage content is 18.71%), and the average value of R c5 /R i5 is 1.2, Dv50 is 16.3 ⁇ m Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 precursors, according to the ratio of the number of moles of Li to the number of moles of transition metal elements (the sum of the number of moles of Ni, Co and Mn) is 1.05:0.997 in a high-speed mixer with a speed of 300r/min mixed for 20min to obtain a mixture, the The mixture was placed in an oxygen kiln, heated to 890°C at 5°C/min, kept for 12 hours, taken out after natural cooling, and passed through a 300-mesh sieve to obtain nickel-cobalt-lithium manganese oxide, namely NCM5515.
  • R c5 is the radius of the smallest circumscribed circle of the profile of the Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 precursor particle
  • R i5 is the largest inscribed circle of the profile of the Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 precursor particle of the radius.
  • NCM6010 in Table 2 is LiNi 0.6 Co 0.1 Mn 0.3 O 2
  • NCM8309 is LiNi 0.83 Co 0.09 Mn 0.08 O 2 ; by adjusting the ratio of the moles of Li to the moles of transition metal elements when preparing NCM5515, NCM6010 and NCM8309 satisfy the above chemical formula.
  • Example 1-1 to Example 1-6 and Comparative Example 1 From Example 1-1 to Example 1-6 and Comparative Example 1, it can be seen that when the value of R c /R i is within the scope of the present application, the obtained lithium ion battery has good low-temperature rate performance and normal temperature rate performance.
  • the area percentage of the first particle, the area percentage of the second particle, the value of Dv50 and (Dv90-Dv10)/Dv50 of the positive electrode active material will generally affect the performance of the lithium ion battery, from embodiment 2-1 to embodiment 2-7 It can be seen that when the area percentage of the first particle, the area percentage of the second particle, the Dv50 of the positive electrode active material and the value of (Dv90-Dv10)/Dv50 are within the scope of the present application, the resulting lithium-ion battery has a good performance Low temperature rate performance and room temperature rate performance.
  • the type and mass percentage of chain carbonate and cyclic carbonate in the electrolyte, and the value of ⁇ 1 / ⁇ 2 can affect the performance of lithium-ion battery usually, from embodiment 2-1, embodiment 3-1 to Embodiment 3-7 can find out, when the kind and mass percentage of chain carbonate and cyclic carbonate, and ⁇ 1 / ⁇ 2 value in the scope of the present application, the lithium ion battery obtained has good Low temperature rate performance.
  • Example 4-1 to Example 4-9 it can be seen that adding a sulfonate compound to the electrolyte can improve the cycle performance of lithium-ion batteries at high temperatures and the dissolution of manganese on the negative electrode sheet Phenomenon. From Example 4-1 to Example 4-9, it can be seen that when the type and mass percentage of the sulfonate compound are within the scope of the application, the obtained lithium ion battery has good high-temperature cycle performance and the negative electrode sheet The dissolution of manganese is less. And, when the value of A/B is within the range of the present application, the resulting lithium-ion battery has good high-temperature cycle performance and less manganese dissolution on the negative electrode sheet.
  • the type of element in the positive electrode active material usually affects the performance of the lithium ion battery, as can be seen from Example 2-1, Example 5-1 to Example 5-9, when the positive electrode active material includes Mn and the metal element M1 , the obtained lithium-ion battery has good low-temperature rate performance.
  • the metal element M2 is included in the second particles and its type and mass percentage are within the scope of the present application, and the resulting lithium-ion battery has good low-temperature rate performance.

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Abstract

本申请提供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，在正极材料层截面的扫描电子显微镜照片中，面积大于5μm2的正极活性材料颗粒的轮廓的最小外接圆的半径为Rc，面积大于5μm2的正极活性材料颗粒的轮廓的最大内切圆的半径为Ri，满足1＜Rc/Ri的平均值≤3。本申请提供的电化学装置，正极材料层中的正极活性材料满足1＜Rc/Ri的平均值≤3，能够有效提高锂离子的传输效率，从而提高电化学装置在常温和低温下的倍率性能。

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。但随着锂离子电池的广泛应用，市场对锂离子电池的综合性能提出更高的要求。
锂离子电池中的正极活性材料、负极活性材料和电解液是影响锂离子电池性能的重要参数。其中，正极活性材料的选择会影响锂离子的传输效率，从而影响电化学装置的电化学性能，例如倍率性能。但现有的正极活性材料有待进一步优化，以提高电化学装置的倍率性能。
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，以提高电化学装置在低温和常温下的倍率性能。
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，在正极材料层截面的扫描电子显微镜照片中，面积大于5μm 2的正极活性材料颗粒的轮廓的最小外接圆的半径为R c，面积大于5μm 2的正极活性材料颗粒的轮廓的最大内切圆的半径为R i，满足1＜R c/R i的平均值≤3。例如，R c/R i的平均值可以为1.1、1.5、1.8、2、2.3、2.5、2.8、3或为其间的任意范围。不限于任何理论，本申请提供的电化学装置，其中，正极材料层中的正极活性材料满足1＜R c/R i的平均值≤3，能够有效提高锂离子在充放电过程中的传输效率，从而提高电化学装置在常温和低温(例如温度小于或等于0℃)下的倍率性能。这可能是由于，R c/R i的平均值处于上述范围的正极材料层，其形貌能使得正极活性材料在较大倍率的循环中能够维持稳定的晶体结构，并有效改善正极活性材料的锂离子嵌入、脱嵌动力学，提供良好的锂离子传输性能，从而提高电化学装置的倍率性能。在本申请中，正极材料层的截面是指沿正极材料层厚度方向横截得到。
在本申请的一些实施方案中，面积大于5μm 2的正极活性材料颗粒包括第一颗粒和第二颗粒，第一颗粒的轮廓的最小外接圆的半径为R c1，第一颗粒的轮廓的最大内切圆的半径为R i1，满足1＜R c1/R i1的平均值≤1.5；第二颗粒的轮廓的最小外接圆的半径为R c2，第二颗粒的轮廓的最大内切圆的半径为R i2，满足1.5＜R c2/R i2的平均值≤3。
基于正极材料层的截面面积，第一颗粒的面积百分比大于0％且小于等于50％，第二颗粒的面积百分比B为30％至80％。例如，R c1/R i1的平均值可以为1.1、1.2、1.3、1.4、1.5或为其间的任意范围；R c2/R i2的平均值可以为1.6、2、2.5、3或为其间的任意范围；第一颗粒的面积百分比可以为1％、5％、10％、15％、20％、25％、30％、35％、40％、45％、50％或为其间的任意范围；第二颗粒的面积百分比B可以为30％、35％、40％、45％、50％、55％、60％、65％、70％、75％、80％或为其间的任意范围。
第一颗粒与第二颗粒以上述比例分布于正极材料层，在压实工艺后，实现正极材料层中不同R c/R i值的颗粒间的交错分布，改善了正极活性材料和导电剂的分布网络，从而在有效减少正极材料层内界面副反应的同时，改善锂离子传输效率及正极极片内部电子电导率，实现对电化学装置倍率性能及循环性能的有效改善。当第二颗粒的面积百分比B过小时(例如小于30％)，第一颗粒的面积百分比过大，正极极片的压实密度减小，影响锂离子的传输效率；当第二颗粒的面积百分比B过大时(例如大于80％)，同样会导致正极极片的压实密度减小，影响锂离子的传输效率，从而影响电化学装置在常温和低温下的倍率性能。通过调控第一颗粒的面积百分比和第二颗粒的面积百分比在本申请的范围内，有利于提高电化学装置在常温和低温下的倍率性能。在本申请中，正极极片的压实密度是指正极极片中正极材料层的压实密度。
在本申请的一些实施方案中，第一颗粒的平均截面面积小于第二颗粒的平均截面面积，有利于减小锂离子传输路径，改善电化学装置的倍率性能。
在本申请的一些实施方案中，电化学装置满足条件(a)至(b)中的至少一者：(a)正极活性材料包括锰酸锂；锰酸锂包括掺杂锰酸锂和/或含有包覆层的锰酸锂。本申请对掺杂锰酸锂中的掺杂元素没有特别限制，只要能实现本申请的目的即可，例如掺杂元素可以包括但不限于Al、Nb、Mg、Ti、F、B、Zr、W、Sr、Y、Ce或La中的至少一种。本申请对含有包覆层的锰酸锂中的包覆层中的元素没有特别限制，只要能实现本申请的目的即可，例如包覆层中的元素可以包括但不限于Al、Sr、Zr、Ti或B中的至少一种。(b)正极活性材料包括锂 元素和过渡金属元素的复合金属氧化物，过渡金属元素包括Mn和金属元素M1，金属元素M1包括Ni、Co或Fe中的至少一种。基于正极活性材料的质量，Mn的质量百分含量为30％至65％，金属元素M1的质量百分含量为2％至25％。电化学装置满足条件(a)至(b)中的至少一者，均有利于改善电化学装置的循环性能和低温倍率性能。
在本申请的一些实施方案中，第二颗粒包括金属元素M2，金属元素M2包括Al、Mg或Nb中的至少一种。
在本申请的一些实施方案中，基于第二颗粒的质量，金属元素M2的质量百分含量为0.1％至3％。例如，金属元素M2的质量百分含量可以为0.1％、0.3％、0.5％、0.8％、1％、1.3％、1.5％、1.8％、2％、2.5％、3％或为其间的任意范围。
在相关技术中，含锰的正极活性材料(例如锰酸锂)被广泛应用于电化学装置中，例如锂离子电池。但是锰酸锂中存在的Mn 3+易发生歧化反应，导致锰(Mn 2+)溶出，然后通过电解液迁移至负极，破环负极的固体电解质界面(SEI)膜，而修复SEI膜会造成活性锂损失，从而影响锂离子电池的循环性能和倍率性能。在本申请中，负极可以是指负极极片。
本申请的发明人发现，对于包括含锰的正极活性材料的电化学装置，当正极活性材料包括金属元素M1，通过选择上述金属元素M1，有利于改善锰溶出现象，从而减少对负极SEI膜的破坏，及修复SEI膜消耗锂造成的活性锂损失，从而提高电化学装置的循环性能和倍率性能。
本申请的发明人发现，当第二颗粒包括金属元素M2，通过选择上述金属元素M2，可以减少低温充放电过程中第二颗粒与电解液的界面副反应，从而改善正极极片内阻，提升电化学装置的低温倍率性能。
本申请的发明人发现，当金属元素M2的质量百分含量过低时(例如低于0.1％)，对第二颗粒与电解液之间的副反应改善不明显。当金属元素M2的质量百分含量过高时(例如高于3％)，无法实现对第二颗粒与电解液之间的副反应进一步改善的同时，会降低正极活性材料的克容量。通过调控金属元素M2的质量百分含量在上述范围内，有利于减少第二颗粒与电解液之间的界面副反应，提高电化学装置的循环性能。在本申请中，负极可以是指负极极片。
在本申请的一些实施方案中，正极活性材料的体积粒度分布满足条件(c)至(d)中的至少一者：(c)9μm≤Dv50≤22μm；(d)0.9≤(Dv90-Dv10)/Dv50≤2。例如，正极活性材料的Dv50可以为9μm、10μm、11μm、12μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm、20μm、21μm、22μm或为其间的任意范围。例如，(Dv90-Dv10)/Dv50的值可以为0.9、1、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9、2或为其间的任意范围。通过调控正极活性材料的体积粒度分布满足条件(c)至(d)中的至少一者，均有利于提高电化学装置在常温和低温下的倍率性能。本申请对正极活性材料的Dv90和Dv10没有特别限制，只要使得(Dv90-Dv10)/Dv50的值在上述范围内即可，例如，正极活性材料的Dv90为15μm至40μm，正极活性材料的Dv10为0.5μm至6μm。其中，(Dv90-Dv10)/Dv50的值主要反映正极活性材料的粒径分布情况。
在本申请的一些实施方案中，电化学装置还包括电解液，电解液包括链状碳酸酯和环状碳酸酯，基于电解液的质量，链状碳酸酯的质量百分含量为ω 1，环状碳酸酯的质量百分含量ω 2为25％至50％，满足ω 1/ω 2为0.75至2.5。例如，环状碳酸酯的质量百分含量ω 2可以为25％、30％、35％、40％、45％、50％或为其间的任意范围；ω 1/ω 2的值可以为0.75、1、1.25、1.5、1.75、2、2.25、2.5或为其间的任意范围。
不限于任何理论，在调控正极活性材料中R c/R i平均值的同时，电解液中包括链状碳酸酯和环状碳酸酯，使得正极活性材料与电解液之间产生协同作用，可以改善锂离子的传输路径，尤其是改善正极活性材料与电解液的界面处的锂离子传输效率，从而改善电化学装置的倍率性能。
不限于任何理论，当环状碳酸酯的质量百分含量ω 2过低时(例如低于25％)，环状碳酸酯不能与链状碳酸酯之间形成良好的协同作用以改善锂离子的传输效率；当环状碳酸酯的质量百分含量ω 2过高时(例如高于50％)，导致电解液的粘度增大，不利于锂离子的传输，从而影响电化学装置的倍率性能。当ω 1/ω 2的值小于0.75或大于2.5，均会影响环状碳酸酯与链状碳酸酯之间的协同作用，从而影响锂离子的传输效率。通过调控环状碳酸酯的质量百分含量ω 2和ω 1/ω 2的值在本申请的范围内，正极活性材料可以被充分浸润，从而提高锂离子在正极活性材料与电解液的界面处的传输效率，进而提高电化学装置的倍率性能。
在本申请的一些实施方案中，35％≤ω 1≤65％。例如，链状碳酸酯的质量百分含量为ω 1可以为35％、40％、45％、50％、55％、60％、65％或为其间的任意范围。不限于任何理 论，通过调控链状碳酸酯的质量百分含量ω 1在本申请的范围内，有利于环状碳酸酯与链状碳酸酯之间形成良好的协同作用，改善锂离子的传输效率，从而提高电化学装置的倍率性能。
在本申请的一些实施方案中，链状碳酸酯包括碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸乙丙酯(EPC)、碳酸二丙酯(DPC)、碳酸甲基异丙酯、碳酸甲丁酯或碳酸二丁酯(DBC)中的至少一种。不限于任何理论，通过选择上述链状碳酸酯，有利于改善锂离子的传输效率，提高电化学装置的倍率性能。
在本申请的一些实施方案中，环状碳酸酯包括碳酸亚乙酯(EC)、碳酸亚丙酯(PC)或碳酸亚丁酯(BC)中的至少一种。不限于任何理论，通过选择上述环状碳酸酯，有利于改善锂离子的传输效率，提高电化学装置的倍率性能。
在本申请的一些实施方案中，电解液包括磺酸酯化合物，基于电解液的质量，磺酸酯化合物的质量百分含量为A，满足0.006≤A/B≤0.1。例如，A/B的值可以为0.006、0.008、0.01、0.02、0.04、0.06、0.08、0.1或为其间的任意范围。不限于任何理论，磺酸酯化合物中的硫氧双键有利于提高SEI膜的稳定性，减少溶出锰在负极的沉积，从而提高电化学装置的循环性能。同时，当A/B的值在本申请的范围内时，有利于磺酸酯化合物与正极活性材料之间产生协同作用，在提高SEI膜稳定性的同时，改善锂离子的传输效率，进一步提高电化学装置的倍率性能。
在本申请的一些实施方案中，0.5％≤A≤10％。例如，磺酸酯化合物的质量百分含量A可以为0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或为其间的任意范围。不限于任何理论，当磺酸酯化合物的质量百分含量A过低时(例如低于0.5％)，对SEI膜稳定性的改善不明显；当磺酸酯化合物的质量百分含量A过高时(例如高于10％)，会形成过厚或者过于致密的SEI膜，阻碍锂离子的传输，导致电化学装置的倍率性能下降。
优选地，磺酸酯化合物包括下述结构化合物I-1至I-14中的至少一种。通过选择下述结构的磺酸酯化合物有利于提高SEI膜的稳定性，减少溶出锰在负极的沉积，从而提高电化学装置的循环性能。
Figure PCTCN2021138349-appb-000001
在本申请的一些实施方案中，电化学装置还包括负极极片，负极极片包括负极材料层，负极材料层包括负极活性材料，负极活性材料包括人造石墨、天然石墨或硬碳中的至少一种。不限于任何理论，通过选择上述负极活性材料，更有利于与前述正极活性材料和/或电解液之间形成协同作用，以提高电化学装置的循环性能和倍率性能。
在本申请中，正极活性材料可以包括但不限于复合氧化物和/或复合氧化物的硫化物、硒化物或卤化物中的至少一种。复合氧化物可以包括但不限于LiMn 2O 4、Li(Ni a1Co b1Mn c1)O 2(0<a1<1，0<b1<1，0<c1<1，a1+b1+c1＝1)、LiNi 1-y1Co y1O 2(0<y1<1)、LiNi 2-y3Mn y3O 4(0<y3<2)、Li(Ni a3Co b3Al c3)O 2(0<a3<1，0<b3<1，0<c3<1，a3+b3+c3＝1)或LiMn pFe qPO 4(0<p<1，0<q<1，p+q＝1)或LiFePO 4中的至少一种。
任选地，复合氧化物的表面还可以存在非晶化合物或结晶的化合物，非晶或结晶的化合物可以包括但不限于元素Z的氧化物、元素Z的氢氧化物、元素Z的羟基氧化物、元素Z的碳酸氧盐或元素Z的碱式碳酸盐中的至少一种。其中，元素Z可以包括但不限于Mg、Al、Co、K、Na、Ca、Si、Ti、V、Sn、Ge、Ga、B、As或Zr中的至少一种。
本申请对于表面含有非晶化合物或结晶的化合物的复合氧化物的制备方法没有特别限制，只要能实现本申请的目的即可，例如喷涂法或浸渍法等。
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、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。在本申请中，基于正极材料层的质量，导电剂的质量百分含量为0.5％至5％。
在本申请中，正极材料层中还可以包括正极粘结剂，本申请对正极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙中的至少一种。
在本申请中，正极极片包括正极集流体。其中，正极集流体没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于铝箔、铝合金箔或复合集流体等。在本申请中，对正极集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如厚度为8μm至20μm。
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正极粘结剂。
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负极粘结剂，本申请对负极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于二氟乙烯一六氟丙烯共聚物、聚偏二氟乙烯、聚丙烯睛、聚甲基丙烯酸甲醋、聚乙烯醇、羧甲基纤维素、羟丙基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙中的至少一种。
在本申请中，负极极片包括负极集流体。其中，负极集流体没有特别限制，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。
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负极粘结剂。
在本申请中，电解液中还可以包括非水溶剂，本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述羧酸酯化合物可以包括但不限于乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸正丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、丁酸丁酯、γ-丁内酯、乙酸2,2-二氟乙酯、戊内酯、丁内酯、2-氟乙酸乙酯、2,2-二氟乙酸乙酯、三氟乙酸乙酯、2,2,3,3,3-五氟丙酸乙酯、2,2,3,3,4,4,4,4-七氟丁酸甲酯、4,4,4-三氟-3-(三氟甲基)丁酸甲酯、2,2,3,3,4,4,5,5,5,5-九氟戊酸乙酯、2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-十七氟壬酸甲酯或2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-十七氟壬酸乙酯中的至少一种。上述醚化合物可以包括但不限于乙二醇二甲醚、二乙二醇二甲醚、四乙二醇二甲醚、二丁醚、四氢呋喃、2-甲基四氢呋喃或双(2,2,2-三氟乙基)醚中的至少一种。上述其它有机溶剂可以包括但不限于乙基乙烯基砜、甲基异丙基砜、异丙基仲丁基砜、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。
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六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、双草酸硼酸锂(LiB(C 2O 4) 2)、二氟草酸硼酸锂(LiBF 2(C 2O 4))、六氟锑酸锂(LiSbF 6)、全氟丁基磺酸锂(LiC 4F 9SO 3)、高氯酸锂(LiClO 4)、铝酸锂(LiAlO 2)、四氯铝酸锂(LiAlCl 4)、双磺酰亚胺锂(LiN(C xF 2x+1SO 2)(C yF 2y+1SO 2)，其中x和y分别为小于或等于4的自然数)、氯化锂(LiCl)、氟化锂(LiF)中的至少一种。优选地，锂盐包括LiPF 6。本申请对锂盐的浓度没有特别限制，只要能实现本申请的目的即可，例如浓度为0.5mol/L至3mol/L，优选为0.5mol/L至2mol/L，进一步优选为0.6mol/L至1.5mol/L。
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)类隔离膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰 亚胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜等中的至少一种。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，隔离膜可以包括隔离膜基材层和表面处理层。隔离膜基材层可以为具有多孔结构的无纺布、膜或复合膜，隔离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，隔离膜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。
聚合物层中包含聚合物，聚合物的材料可以包括但不限于偏氟乙烯、偏氟乙烯-六氟丙烯共聚物、聚丙烯腈、聚酰亚胺、丙烯腈-丁二烯共聚物、丙烯腈-苯乙烯-丁二烯共聚物、聚甲基丙烯酸甲酯、聚丙烯酸甲酯、聚丙烯酸乙酯、丙烯酸-苯乙烯共聚物、聚二甲基硅氧烷、聚丙烯酸钠或羧甲基纤维素中的至少一种。无机物层可以包括但不限于无机颗粒和无机物层粘结剂，本申请对无机颗粒没有特别限制，例如，可以包括但不限于陶瓷、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。本申请对无机物层粘结剂没有特别限制，例如可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。
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，包含本申请任一实施方案中的电化学装置。本申请提供的电化学装置具有良好的倍率性能和循环性能，从而本申请提供的电子装置具有较长的使用寿命。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施方案中，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。
本申请提供了一种电化学装置，其包括正极极片，所述正极极片包括正极材料层，正极材料层包括正极活性材料，在正极材料层的横截面的扫描电子显微镜照片中，横截面积大于5μm 2的正极活性材料颗粒的轮廓的最小外接圆的半径为R c，横截面积大于5μm 2的颗粒的轮廓的最大内切圆的半径为R i，满足1＜R c/R i的平均值≤3。本申请提供的电化学装置，其中，正极材料层中的正极活性材料满足1＜R c/R i的平均值≤3，能够有效提高正极极片的锂离子传输效率，从而提高电化学装置在常温和低温下的倍率性能。
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为本申请一种实施例中的正极材料层截面的扫描电子显微镜照片；
图2为本申请一种实施例中的正极极片的截面示意图。
附图标记：10、正极集流体，20、正极材料层，21、正极活性材料。
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。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实施例，都属于本申请保护的范围。
图1示出了本申请一种实施例中的正极材料层截面的扫描电子显微镜照片，从图中可以看出，正极活性材料21的颗粒的大小和形状存在差异。颗粒C的轮廓的最小外接圆为R1，颗粒C的轮廓的最大内切圆为R2；颗粒D的轮廓的最小外接圆为R3，颗粒D的轮廓的最大内切圆为R4。其中，颗粒C为本申请中第一颗粒的示例，颗粒D为本申请中第二颗粒的示例。
图2示出了本申请一种实施例中的正极极片的截面示意图，正极集流体10的两个表面上均存在正极材料层20，图中箭头所示方向为正极材料层20的厚度方向，本申请前述正极材料层的截面是指沿图中箭头方向横截得到。
需要说明的是，在本申请的具体实施方式中，第一颗粒的R c1/R i1的平均值与第二颗粒的R c2/R i2的平均值可以通过控制原料的颗粒的轮廓最小外接圆的半径与最大内切圆的半径的比值，以及原料的Dv50，并综合调整正极活性材料制备过程中的搅拌速度或焙烧温度等条件来控制。
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：
R i和R c的测量：
在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以1C的恒电流放电至2.8V，拆解锂离子电池，使用DMC清洗正极极片，然后在60℃烘干处理2h后；使用离子抛光仪沿正极极片自身厚度方向切割正极极片，得到 平整的正极极片截面；使用扫描电子显微镜(SEM)对截面进行测试；选择放大倍数为1000倍的SEM图像。
采用软件Image J对上述SEM图像进行图形形貌识别，随机选择100个截面完全位于图像视野内、且截面面积大于5μm 2的颗粒，采用算法分别对颗粒的最大内切圆的半径R i和最小外接圆的半径R c进行计算(参考“Kenneth C.Williams,Wei Chen,Sebastian Weeger,Timothy J.Donohue,Particle shape characterisation and its application to discrete element modelling,Particuology,Volume 12,2014,Pages 80-89,ISSN 1674-2001”)。
R c1、R i1、R c2、R i2的测量方法与R i和R c的相同。
R c3和R i3的测量是先将二氧化锰制备成浆料然后涂覆在基材上制成膜层，并参照R i和R c的测量方法进行测量，其中浆料的固含量(例如75wt％)和基材的种类没有特别限制，只要能实现本申请的目的即可。R c4和R i4、R c5和R i5的测量参照R c3和R i3的测量方法。
第一颗粒和第二颗粒面积的测量及其面积百分比的计算：
采用软件Image J计算颗粒面积，根据识别的R c/R i比值确定颗粒归属于第一颗粒或第二颗粒，不同归属颗粒的加和记为第一颗粒或第二颗粒的面积，第一颗粒面积百分比为第一颗粒面积/图像面积×100％，第二颗粒面积百分比为第二颗粒面积/图像面积×100％。
正极活性材料粒径的测量：
使用马尔文粒度测试仪对正极活性材料的粒径进行测量，将正极活性材料分散到乙醇中，超声30min后加入到马尔文粒度测试仪中，开始测试。正极活性材料在体积基准中的粒度分布中，从小粒径侧起，到达体积累积10％的粒径即为正极活性材料的Dv10，到达体积累积50％的粒径即为正极活性材料的Dv50，到达体积累积90％的粒径即为正极活性材料的Dv90。
元素含量的测试：
根据上述得到的正极极片截面的SEM图像，根据图像中颗粒粒径大小及面积确定第二颗粒，然后使用能谱仪(EDS)测试，确定掺杂元素及元素含量；
将用DMC清洗后的正极极片的正极材料层用刮刀刮下，用混合溶剂溶解(例如，0.4g正极活性材料使用10ml王水(硝酸与盐酸按照体积比1:1混合)与2ml的HF的混合溶剂)，定容至100mL，然后使用电感耦合等离子(ICP)分析仪测试溶液中元素的含量。
正极极片压实密度的测试：
在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以1C的恒电流放电至2.8V，拆解锂离子电池，使用DMC清洗正极极片，然后在60℃烘干处理2h后，裁切5cm×5cm大小的正极极片5片，通过万分尺分别测量正极极片的厚度，记为d0cm；用刮刀刮下正极极片中的正极材料层，通过天平称量正极材料层的质量，记为m g，通过万分尺测量去除正极材料层的正极集流体厚度记为d cm，按照下式计算正极材料层的压实密度：
压实密度P＝m/[25×(d0-d)]，单位g/cm 3。
正极材料层的压实密度为上述裁切得到的5片正极极片中正极材料层压实密度的平均值。
正极材料层中颗粒粒径测试：
在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以1C的恒电流放电至2.8V，拆解锂离子电池，将拆解的正极极片或负极极片在真空中400℃烧成粉状后，使用粒度分析仪测试粒度，得到Dv10、Dv50、Dv90的值。
其中，Dv90是指在体积基准的粒度分布中，从小粒径侧起、达到体积累积90％的粒径，Dv50是指在体积基准的粒度分布中，从小粒径侧起、达到体积累积50％的粒径，Dv10是指在体积基准的粒度分布中，从小粒径侧起、达到体积累积10％的粒径。
倍率性能和25℃循环性能的测试：
(1)25℃2C常温倍率性能和25℃循环性能
在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以0.2C的恒电流放电至2.8V，记录放电容量为D 01；将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以2C的恒电流放电至2.8V，记录放电容量为D 1，25℃2C倍率保持率(％)＝D 1/D 01×100％。
按照上述操作步骤使锂离子电池进行多次“0.5C充电-2C放电”的循环流程，循环1000圈，测试第1000次循环后的放电容量为D 10。25℃循环1000圈后的容量保持率(％)＝D 10/D 01×100％。
(2)-10℃1C低温倍率性能
在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，然后以1C的恒电流放电至2.8V，记录放电容量为D 02；在25℃条件下，将锂离子电池以0.5C恒流充电至4.2V，再在4.2V条件下恒压充电至0.05C，将温度调至-10℃，电芯放置30min后，然后以1C的恒电流放电至2.8V，记录放电容量为D 2。-10℃1C倍率保持率(％)＝D 2/D 02×100％。
循环性能的测试：
40℃500圈循环容量保持率：
将锂离子电池在40℃下以0.5C恒流充电至4.2V，然后恒压充电至电流为0.05C，静置5min，然后以1C恒流放电至2.8V，此为一次充放电循环，并记录放电容量记为D 03；按照上述操作步骤使锂离子电池进行500次循环，测试第500次循环后的放电容量为D 3。40℃循环500圈后的容量保持率(％)＝D 3/D 03×100％。
负极极片锰含量的测试：
将进行40℃500圈循环后处于满放状态的锂离子电池拆解，取负极极片用DMC清洗，然后在60℃烘干处理2h后，将负极极片的负极材料层用刮刀刮下，用混合溶剂溶解(例如，0.4g负极活性材料使用10ml王水(硝酸与盐酸按照体积比1:1混合))，定容至100ml，然后使用ICP分析仪测试溶液中锰元素的含量。
实施例1-1
<正极极片的制备>
称取碳酸锂203.3kg(其中锂元素质量百分含量为18.71％)，R c3/R i3的平均值为2.9、Dv50为17.2μm的二氧化锰1000kg(其中Mn元素质量百分含量为60.22％)、含M2金属元素的化合物三氧化二铝56.2kg(Al 2O 3，铝元素质量百分含量52.91％)在高速混合机中以转速300r/min混合20min得到混合物，将混合物置于空气窑炉中，以5℃/min升温至790℃，保持24h，自然冷却后取出，过300目筛后得到含锰复合金属氧化物，即为LMO。其中，R c3为二氧化锰颗粒的轮廓的最小外接圆的半径，R i3为二氧化锰颗粒的轮廓的最大内切圆的半径。
将正极活性材料LMO、导电剂Super P、粘结剂聚偏二氟乙烯按照质量比为96:2.4:1.6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状，获得正极浆料，其中正极浆料的固含量为75wt％。将正极浆料均匀涂覆于厚度为10μm的正极 集流体铝箔的一个表面上，将铝箔在85℃下烘干，得到涂层厚度为110μm的单面涂覆有正极材料层的正极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极材料层的正极极片。然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4h，得到规格为74mm×867mm的正极极片。其中，正极活性材料的R c/R i的平均值为2.9，Dv50为17.9μm。
<负极极片的制备>
将负极活性材料人造石墨、导电剂Super P、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按照质量比为96.4:1.5:0.5:1.6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70wt％。将负极浆料均匀涂覆于厚度为10μm的负极集流体铜箔的一个表面上，将铜箔在85℃下烘干，得到涂层厚度为130μm的单面涂覆有负极材料层的负极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂布负极材料层的负极极片。然后经过冷压、裁片、分切后，在120℃的真空条件下干燥12h，得到规格为79mm×972mm的负极极片。
<电解液的制备>
在含水量<10ppm的氩气气氛手套箱中，将链状碳酸酯DEC和环状碳酸酯EC按照质量比57.5:30混合得到基础溶剂，然后向基础溶剂中加入锂盐LiPF 6溶解并混合均匀。其中，基于电解液的质量，LiPF 6的质量百分含量为12.5％，其余为基础溶剂。
<隔离膜的制备>
将水性聚偏二氟乙烯、三氧化二铝、聚丙烯按照质量比为1:8:1混合，加入去离子水中，搅拌得到固含量为50wt％的涂层浆料。将涂层浆料均匀涂覆在厚度为5μm的PE薄膜(Celgard公司提供)的一个表面，在85℃下烘干，得到涂层厚度为5μm的单面涂覆有涂层的隔离膜。在隔离膜的另一个表面上重复以上步骤，即得到双面涂布涂层的隔离膜。然后经过烘干、冷压，得到隔离膜。其中，隔离膜的孔隙率为39％。
<锂离子电池的制备>
将上述制备得到的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间以起到隔离的作用，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。其中，化成条件是以0.02C恒流充电到3.3V，再以0.1C恒流充电到3.6V。
实施例1-2至实施例1-4
除了调整二氧化锰的R c3/R i3的平均值和Dv50使得正极活性材料的R c/R i的平均值和Dv50如表1所示以外，其余与实施例1-1相同。
实施例1-5和实施例1-6
除了在制备LMO时将原料中的二氧化锰替换为四氧化三锰，并调整四氧化三锰的R c4/R i4的平均值和Dv50使得正极活性材料的R c/R i的平均值和Dv50如表1所示以外，其余与实施例1-1相同。其中，R c4为四氧化三锰颗粒的轮廓的最小外接圆的半径，R i4为四氧化三锰颗粒的轮廓的最大内切圆的半径。
实施例2-1
除了在<正极极片的制备>中，采用正极活性材料LMO、正极活性材料LiNi 0.55Co 0.15Mn 0.3O 2(NCM5515)、导电剂Super P、粘结剂聚偏二氟乙烯按照质量比为76.8:19.2:2.4:1.6进行混合，加入NMP，在真空搅拌机作用下搅拌至体系成均一状，获得固含量为75wt％的正极浆料，以及调整二氧化锰的R c3/R i3的平均值和Dv50使得第二颗粒的R c/R i的平均值和正极活性材料的Dv50如表2所示以外，其余与实施例1-1相同。
上述NCM5515采用以下方法制得：将碳酸锂(其中锂元素质量百分含量为18.71％)，以及R c5/R i5的平均值为1.2、Dv50为16.3μm的Ni 0.55Co 0.15Mn 0.3(OH) 2前驱体，按照Li的摩尔数与过渡金属元素的摩尔数(Ni、Co和Mn的摩尔数之和)的比值为1.05:0.997在高速混合机中以转速300r/min混合20min得到混合物，将混合物置于氧气窑炉中，以5℃/min升温至890℃，保持12h，自然冷却后取出，过300目筛后得到镍钴锰酸锂，即为NCM5515。其中，R c5为Ni 0.55Co 0.15Mn 0.3(OH) 2前驱体颗粒的轮廓的最小外接圆的半径，R i5为Ni 0.55Co 0.15Mn 0.3(OH) 2前驱体颗粒的轮廓的最大内切圆的半径。
实施例2-2至实施例2-4、实施例2-7
除了按照表2混合相应正极活性材料，调整二氧化锰的R c3/R i3的平均值和Dv50，和/或，Ni 0.55Co 0.15Mn 0.3(OH) 2前驱体的R c5/R i5的平均值和Dv50，所得R c1/R i1的平均值、R c2/R i2的平均值、第一颗粒的面积百分比、第二颗粒的面积百分比、正极活性材料的Dv50和正极活性材料的粒径分布(Dv90-Dv10)/Dv50的值如表2所示，其余与实施例2-1相同。其中，表2中的NCM6010为LiNi 0.6Co 0.1Mn 0.3O 2，NCM8309为LiNi 0.83Co 0.09Mn 0.08O 2；通过调整制备NCM5515 时Li的摩尔数与过渡金属元素的摩尔数的比值使得NCM6010和NCM8309满足上述化学式。
实施例2-5和实施例2-6
除了在制备第一颗粒LMO时将原料中的二氧化锰替换为四氧化三锰，并调整四氧化三锰的R c4/R i4的平均值和Dv50，以及，在制备第二颗粒LMO时调整二氧化锰的R c3/R i3的平均值和Dv50，所得R c1/R i1的平均值、R c2/R i2的平均值、第一颗粒的面积百分比、第二颗粒的面积百分比、正极活性材料的Dv50和正极活性材料的粒径分布(Dv90-Dv10)/Dv50的值如表2所示，其余与实施例2-1相同。
实施例3-1至实施例3-7
除了按照表3调整链状碳酸酯和环状碳酸酯的种类及含量得到基础溶剂以外，其余与实施例2-1相同。
实施例4-1至实施例4-9
除了在<电解液的制备>中，电解液中进一步加入磺酸酯化合物，并按照表4调整磺酸酯化合物的种类和质量百分含量以外，其余与实施例2-1相同。
实施例5-1至实施例5-6
除在制备LMO的过程中按照表5加入含M2金属元素的化合物并调控其含量使得金属元素M2质量百分含量如表5所示以外，其余与实施例2-1相同。
实施例5-7
除了使用商用的Dv50为1.0μm的LiFePO 4(记为LFP)替换NCM5515以外，其余与实施例5-3相同。
实施例5-8
除了使用商用的Dv50为1.0μm的LiMn 0.75Fe 0.25PO 4(记为LMFP)替换NCM5515以外，其余与实施例5-3相同。
实施例5-9
除了使用商用的Dv50为1.0μm的LFP替换部分NCM5515，使得LMO、NCM5515、LFP、 Super P、聚偏二氟乙烯的质量比为76.8:9.2:10:2.4:1.6以外，其余与实施例5-3相同。
对比例1
除了R c/R i的平均值和正极活性材料的Dv50如表1所示以外，其余与实施例1-1相同。
各实施例和对比例的制备参数及性能测试如表1至表5所示。
表1
Figure PCTCN2021138349-appb-000002
从实施例1-1至实施例1-6、对比例1中可以看出，当R c/R i的值在本申请的范围内，得到的锂离子电池同时具有良好的低温倍率性能和常温倍率性能。
表2
Figure PCTCN2021138349-appb-000003
第一颗粒的面积百分比、第二颗粒的面积百分比、正极活性材料的Dv50和(Dv90-Dv10)/Dv50的值通常会影响锂离子电池的性能，从实施例2-1至实施例2-7可以看出，当第一颗粒的面积百分比、第二颗粒的面积百分比、正极活性材料的Dv50和(Dv90-Dv10)/Dv50的值在本申请的范围内时，得到的锂离子电池具有良好的低温倍率性能和常温倍率性能。
表3
Figure PCTCN2021138349-appb-000004
电解液中链状碳酸酯和环状碳酸酯的种类和质量百分含量，以及ω 1/ω 2的值通常会影响锂离子电池的性能，从实施例2-1、实施例3-1至实施例3-7可以看出，当链状碳酸酯和环状碳酸酯的种类和质量百分含量，以及ω 1/ω 2的值在本申请的范围内时，得到的锂离子电池具有良好的低温倍率性能。
表4
Figure PCTCN2021138349-appb-000005
注：表4中的“/”表示不存在对应制备参数或物质。
从实施例2-1、实施例4-1至实施例4-9可以看出，在电解液中加入磺酸酯化合物后可以改善锂离子电池在高温下的循环性能以及负极极片上的锰溶出现象。从实施例4-1至实施例4-9可以看出，当磺酸酯化合物的种类和质量百分含量在本申请的范围内，得到的锂离子电池具有良好的高温循环性能且负极极片上的锰溶出量较少。以及，当A/B的值在本申请的范围内，得到的锂离子电池具有良好的高温循环性能且负极极片上的锰溶出量较少。
表5
Figure PCTCN2021138349-appb-000006
正极活性材料中的元素种类通常会影响锂离子电池的性能，从实施例2-1、实施例5-1至实施例5-9可以看出，当正极活性材料中包括Mn和金属元素M1时，得到的锂离子电池具有良好的低温倍率性能。此外，还可以看出，第二颗粒中包含金属元素M2且其种类和质量百分含量在本申请的范围内，得到的锂离子电池具有良好的低温倍率性能。
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 (15)

  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，在所述正极材料层截面的扫描电子显微镜照片中，面积大于5μm 2的正极活性材料颗粒的轮廓的最小外接圆的半径为R c，面积大于5μm 2的正极活性材料颗粒的轮廓的最大内切圆的半径为R i，满足1＜R c/R i的平均值≤3。
  2. 根据权利要求1所述的电化学装置，其中，所述面积大于5μm 2的正极活性材料颗粒包括第一颗粒和第二颗粒，所述第一颗粒的轮廓的最小外接圆的半径为R c1，所述第一颗粒的轮廓的最大内切圆的半径为R i1，满足1＜R c1/R i1的平均值≤1.5；所述第二颗粒的轮廓的最小外接圆的半径为R c2，所述第二颗粒的轮廓的最大内切圆的半径为R i2，满足1.5＜R c2/R i2的平均值≤3。
  3. 根据权利要求2所述的电化学装置，其满足：
    基于所述正极材料层的截面面积，所述第一颗粒的面积百分比大于0％且小于或等于50％，所述第二颗粒的面积百分比B为30％至80％；和/或，
    所述第一颗粒的平均截面面积小于第二颗粒的平均截面面积。
  4. 根据权利要求1所述的电化学装置，其还包括电解液，所述电解液包括链状碳酸酯和环状碳酸酯，基于所述电解液的质量，所述链状碳酸酯的质量百分含量为ω 1，所述环状碳酸酯的质量百分含量ω 2为25％至50％，满足ω 1/ω 2为0.75至2.5。
  5. 根据权利要求1所述的电化学装置，其中，满足条件(a)至(b)中的至少一者：
    (a)所述正极活性材料包括锰酸锂；
    (b)所述正极活性材料包括锂元素和过渡金属元素的复合金属氧化物，所述过渡金属元素包括Mn和金属元素M1，所述金属元素M1包括Ni、Co或Fe中的至少一种。
  6. 根据权利要求2所述的电化学装置，其中，所述第二颗粒包括金属元素M2，所述金属元素M2包括Al、Mg或Nb中的至少一种。
  7. 根据权利要求2所述的电化学装置，其中，所述第二颗粒包括金属元素M2，基于所述第二颗粒的质量，所述金属元素M2的质量百分含量为0.1％至3％。
  8. 根据权利要求1所述的电化学装置，所述正极活性材料的体积粒度分布满足条件(c)至(d)中的至少一者：
    (c)9μm≤Dv50≤22μm；
    (d)0.9≤(Dv90-Dv10)/Dv50≤2。
  9. 根据权利要求4所述的电化学装置，其中，所述链状碳酸酯包括碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、碳酸乙丙酯、碳酸二丙酯、碳酸甲基异丙酯、碳酸甲丁酯或碳酸二丁酯中的至少一种。
  10. 根据权利要求4所述的电化学装置，其中，所述环状碳酸酯包括碳酸亚乙酯、碳酸亚丙酯或碳酸亚丁酯中的至少一种。
  11. 根据权利要求3所述的电化学装置，其还包括电解液，所述电解液包括磺酸酯化合物，基于所述电解液的质量，所述磺酸酯化合物的质量百分含量为A，满足0.006≤A/B≤0.1。
  12. 根据权利要求11所述的电化学装置，其中，0.5％≤A≤10％。
  13. 根据权利要求11所述的电化学装置，其中，所述磺酸酯化合物包括下述结构化合物I-1至I-14中的至少一种：
    Figure PCTCN2021138349-appb-100001
  14. 根据权利要求1所述的电化学装置，其还包括负极极片，所述负极极片包括负极材料层，所述负极材料层包括负极活性材料，所述负极活性材料包括人造石墨、天然石墨或硬碳中的至少一种。
  15. 一种电子装置，其包括权利要求1至14中任一项所述的电化学装置。
PCT/CN2021/138349 2021-12-15 2021-12-15 一种电化学装置和电子装置 WO2023108481A1 (zh)

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