WO2022178655A1 - 电化学装置和电子装置 - Google Patents

电化学装置和电子装置 Download PDF

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Publication number
WO2022178655A1
WO2022178655A1 PCT/CN2021/077397 CN2021077397W WO2022178655A1 WO 2022178655 A1 WO2022178655 A1 WO 2022178655A1 CN 2021077397 W CN2021077397 W CN 2021077397W WO 2022178655 A1 WO2022178655 A1 WO 2022178655A1
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Prior art keywords
positive electrode
active material
current collector
electrode active
thickness
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PCT/CN2021/077397
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English (en)
French (fr)
Inventor
刘胜奇
蔡小虎
王可飞
张青文
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宁德新能源科技有限公司
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Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to PCT/CN2021/077397 priority Critical patent/WO2022178655A1/zh
Priority to CN202211142103.2A priority patent/CN115548251A/zh
Priority to EP21927103.8A priority patent/EP4310945A1/en
Priority to CN202180001858.8A priority patent/CN113348570B/zh
Publication of WO2022178655A1 publication Critical patent/WO2022178655A1/zh
Priority to US18/454,363 priority patent/US20230395787A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/13—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
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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 an electrochemical device and an electronic device.
  • Electrochemical devices such as Li-ion batteries
  • Li-ion batteries are widely used in smart products due to their high energy density, low maintenance, low self-discharge rate, wide operating temperature range, long cycle life, no memory effect, stable operating voltage, and environmental friendliness ( Including mobile phones, notebooks, cameras and other electronic products), power tools and electric vehicles and other fields.
  • electrochemical devices such as fast charging performance.
  • the present application provides an electrochemical device comprising a positive electrode, the positive electrode comprising a current collector and a membrane layer comprising a positive electrode active material, the membrane layer being disposed on at least one surface of the current collector
  • the positive electrode active material includes primary particles and/or secondary particles; when the primary particles in the positive electrode active material satisfy 20% ⁇ A ⁇ 100% based on the mass percentage A of the positive electrode active material, the film Between the sheet layer, the positive electrode active material and the current collector: D l ⁇ Dv99-D c ; when the primary particles in the positive electrode active material satisfy 0 ⁇ A' ⁇ 20% based on the mass percentage A' of the positive electrode active material , between the membrane layer, the positive electrode active material and the current collector: D l ⁇ 1.1Dv99; wherein, D l is the thickness of the membrane layer, D c is the thickness of the current collector, and Dv99 is the cumulative volume percentage of the positive electrode active material The particle size corresponding to 99%.
  • the relationship between the thickness D l of the diaphragm layer and the thickness D c of the current collector satisfies: 0.05 ⁇ D l /D c ⁇ 3.75.
  • the thickness D l of the membrane layer is 1 ⁇ m to 30 ⁇ m.
  • the current collector has a thickness D c of 4 ⁇ m to 20 ⁇ m.
  • the particle size Dv99 of the positive electrode active material is 5 ⁇ m to 48 ⁇ m.
  • the sheet layer has a compacted density of 2 g/dm 3 to 4.3 g/dm 3 .
  • the current collector includes a blank area and a coverage area;
  • the blank area is an area on the current collector that is not covered with a membrane layer, and the blank area has a roughness of 500mm -1 to 2000mm -1 ;
  • the covering area is the area covering the membrane layer on the current collector, and the covering area has a roughness of 1500mm -1 to 8000mm -1 .
  • the electrochemical device further includes an electrolyte, the electrolyte includes an ether dinitrile compound; based on the total mass of the electrolyte, the mass percentage of the ether dinitrile compound is 0.01% to 15% .
  • the conductivity of the electrolyte is greater than or equal to 7 mS/cm.
  • the present application also provides an electronic device, the electronic device comprising the electrochemical device described above in the present application.
  • the present application simultaneously considers the different structural features of the primary particles and the secondary particles, and designs the size of the positive electrode membrane layer, the positive electrode active material and the positive electrode current collector to meet specific requirements. relationship, when it is suitable for fast-charging batteries, it can minimize the risks during the use of fast-charging batteries, and it is not easy to be crushed by particles during cold pressing, which can improve the appearance of the pole piece and have both fast charging performance. , storage performance and cycle performance.
  • 1 is a schematic diagram of the positional relationship between the primary particles and the current collector after cold pressing when the positive electrode active material is primary particles;
  • FIG. 2 is a schematic diagram of the positional relationship between the secondary particles and the current collector after cold pressing when the positive electrode active material is secondary particles;
  • the reference signs are: 1- positive electrode active material particles, 2- positive electrode current collector.
  • the electrochemical device of the present application is, for example, a primary battery, a secondary battery, a fuel cell, a solar cell, or a capacitor.
  • the secondary battery is, for example, a lithium secondary battery, and the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the electrochemical device includes a positive electrode, a negative electrode, and a separator.
  • the positive electrode includes a positive electrode current collector and a positive electrode membrane layer, the positive electrode membrane layer is provided on at least one surface of the positive electrode current collector, the positive electrode membrane layer includes a positive electrode active material, and the positive electrode active material includes primary particles and / or secondary particles.
  • the term "primary particles” refers to active material particles of a single crystal grain, and two or more primary particles may form secondary particles by agglomeration.
  • the primary particles can have any of a variety of shapes, including rods and rectangles, or combinations thereof.
  • the term “secondary particle” is formed by the aggregation of two or more primary particles and does not further aggregate with other particles.
  • the primary particles and the secondary particles each have their own independent structural features.
  • the primary particles may be obtained by over-sintering relatively small particles, and the secondary particles may be obtained by agglomerating the primary particles.
  • the positive electrode active material includes primary particles, and the mass percentage of the primary particles based on the positive electrode active material is 100%, and the positive electrode membrane layer, the positive electrode active material, and the positive electrode current collector satisfy: D 1 ⁇ Dv99 -Dc; wherein, D1 is the thickness of the positive electrode membrane layer; Dc is the thickness of the positive electrode current collector; Dv99 is the corresponding particle size when the cumulative volume percentage of the positive electrode active material reaches 99%.
  • the primary particles are positive active material particles 1 with a single crystal grain and are generally non-spherical, and the friction between the particles is small. Relative slip occurs to compress the positive electrode current collector 2 .
  • the positive current collector is a metal foil.
  • Metal foils include, but are not limited to, copper foils and aluminum foils, for example.
  • the positive current collector is an aluminum foil.
  • the particles are prone to particle scratches, bumps, etc. Appearance problems, the particles are easily crushed during cold pressing and rolling, resulting in poor appearance of the pole pieces, and easily lead to problems such as high temperature storage flatulence and cycle acceleration.
  • the positive electrode active material particles only include secondary particles, the mass percentage of primary particles based on the positive electrode active material is 0%, and the difference between the positive electrode membrane layer and the positive electrode active material satisfies: D l ⁇ 1.1Dv99.
  • the secondary particles are formed by the aggregation of two or more primary particles, and the friction between the particles is relatively large, and relative slippage is not easy to occur when subjected to cold rolling during the preparation of the positive electrode sheet. Therefore, The positive electrode active material particles 1 do not compress the positive electrode current collector 2 .
  • the Dv99 that is 1.1 times that of the secondary particles is used as the design. If the thickness of the positive film layer is less than 1.1 times the particle size Dv99 of the positive electrode active material particles, the particles are prone to appearance problems such as particle scratches and bumps during coating, and particles are also prone to appear during cold rolling. The situation of being crushed results in poor appearance of the pole piece, and it is easy to cause problems such as high temperature storage flatulence and cycle acceleration in the fabricated cell.
  • the positive electrode active material includes primary particles and secondary particles, and the mass percentage of the primary particles based on the positive electrode active material is greater than or equal to 20%, the positive electrode membrane layer, the positive electrode active material, and the positive electrode current collector. between: D l ⁇ Dv99-D c .
  • the mass percentage of the primary particles is greater than or equal to the aforementioned range, the primary particles can be well distributed in the secondary particles, effectively preventing the secondary particles The contact between the particles plays a lubricating role, which is similar to the case where the positive electrode active material only includes primary particles.
  • the positive electrode active material includes primary particles and secondary particles, and the mass percentage of the primary particles based on the positive electrode active material is greater than or equal to 40%.
  • the positive electrode active material includes primary particles and secondary particles, and the mass percentage of the primary particles based on the positive electrode active material is less than 20%, and the positive electrode membrane layer, the positive electrode active material, and the positive electrode current collector satisfy : D l ⁇ 1.1Dv99.
  • the mass percentage of the primary particles is less than the aforementioned range, the primary particles cannot sufficiently hinder the contact between the secondary particles, and the slippage between the secondary particles The difficulty increases, which is similar to the case where the positive electrode active material only includes secondary particles.
  • the thickness of the positive electrode film layer is less than 1.1 times the particle size Dv99 of the positive electrode active material particles, the particles are easily scratched during coating.
  • the positive electrode active material includes primary particles and secondary particles, and the mass percentage of the primary particles based on the positive electrode active material is less than or equal to 10%.
  • Fast charge and discharge technology refers to the technology that the battery uses a charge and discharge rate of more than 1C.
  • the fast charging and discharging technology requires the battery to have the function of high-rate charging, so it is necessary to reduce the ion polarization of the battery cell to realize its high-rate charging function.
  • the inventor found that the battery with thin electrode design can shorten the lithium ion transmission path, thereby reducing the ion polarization of the cell; however, in the battery with thin electrode design, if the size of the main material is unreasonably designed, it is easy to appear during cold pressing. The situation of being crushed by particles, which in turn affects the appearance of the pole piece and the performance of the battery.
  • the different structural characteristics of the primary particles and the secondary particles are considered at the same time, and the sizes of the positive electrode membrane layer, the positive electrode active material and the positive electrode current collector are designed to satisfy a specific relationship , when it is suitable for fast-charging batteries, it can minimize the risks during the use of fast-charging batteries, and it is not easy to be crushed by particles during cold pressing, which can improve the appearance of the pole pieces and improve the battery performance. With fast charging performance, storage performance and cycle performance.
  • the upper limit of the thickness of the cathode membrane layer corresponding to one side of the cathode current collector of the thin electrode is 30 ⁇ m. In some embodiments, the thickness D l of the positive electrode membrane layer is 1 ⁇ m to 30 ⁇ m.
  • a positive electrode sheet with such a thickness of the membrane layer indicates that it has a correspondingly thinner electrode design, which can better shorten the lithium ion transmission path and reduce the ion polarization of the cell. When compared with the positive electrode current collector, When the size of the positive active material is matched, it can have better fast charging performance, storage performance and cycle performance.
  • the thickness D c of the cathode current collector is 4 ⁇ m to 20 ⁇ m.
  • the relationship between the thickness D l of the positive electrode membrane layer and the thickness D c of the positive electrode current collector satisfies: 0.05 ⁇ D1 / Dc ⁇ 3.75 .
  • the thickness ratio of the positive electrode film layer and the positive electrode current collector is within the above range, which can reduce the safety risk; if the ratio is too small, the thickness of the positive electrode film layer is relatively small, which may increase the occurrence of scratches and exposed metal during the production of the electrode. If the ratio is too large, the thickness of the positive film layer is relatively large and the thickness of the positive current collector is relatively small, which may increase the probability of the brittle fracture of the inner ring when the pole piece is cold-pressed and rolled.
  • the relationship between the thickness D l of the positive electrode membrane layer and the thickness D c of the positive electrode current collector satisfies: 0.3 ⁇ D1 / Dc ⁇ 3.1 .
  • the particle size of the positive electrode active material affects the solid-phase diffusion resistance of the positive electrode active material particles in the positive electrode membrane layer, which in turn affects the battery performance.
  • the particle size Dv99 of the positive active material is 5 ⁇ m to 48 ⁇ m. If the particle size of the positive electrode active material is too large, its solid-phase diffusion resistance will be correspondingly large, resulting in a relatively large charge-discharge polarization of the battery, which in turn affects the cycle performance. In some embodiments, the particle size Dv99 of the positive electrode active material is 20 ⁇ m to 40 ⁇ m.
  • the compacted density of the positive membrane layer is 2 g/dm 3 to 4.3 g/dm 3 .
  • the parameters of the positive electrode membrane layer, the positive electrode current collector and the positive electrode active material can be tested according to the following methods, and can also be tested according to other well-known methods in the art, and the obtained test results are all within the error range:
  • the Dv99 of the positive active material can be tested by a Malvern 3000 laser particle sizer, and the average value of the three tests is the test result.
  • the thickness D c of the positive electrode current collector can be tested by using a micrometer. Five points are evenly taken on the surface of the positive electrode current collector and tested, and the average value of the five test values is taken as the test result.
  • the thickness D l of the positive electrode membrane layer is the thickness of the membrane layer on one side of the current collector after the positive electrode sheet is cold-pressed.
  • the thickness of the positive electrode sheet can be tested by using a micrometer. Five points are evenly taken on the surface of the positive electrode sheet and tested, and the average value of the five test values is taken as the test result.
  • the compaction density of the positive electrode film layer the mass of the positive electrode film layer/the area of the positive electrode film layer/the thickness of the positive electrode film layer.
  • the positive electrode active material can be selected from various conventionally known materials known in the art that can be used as electrochemical devices and can reversibly intercalate and deintercalate active ions.
  • the positive active material includes at least one of lithium cobalt oxide, lithium manganate, lithium nickel cobalt manganate (NCM), lithium nickel cobalt aluminate (NCA).
  • the positive electrode film layer also includes a positive electrode conductive agent.
  • the positive electrode conductive agent can be selected from those known in the art that can be used as the positive electrode membrane layer.
  • the positive electrode conductive agent includes but is not limited to natural graphite, artificial graphite, conductive carbon black, acetylene black, Ketjen black, carbon fiber, polyphenylene derivative, metal powder, metal fiber, wherein metal powder and metal Fibers such as, but not limited to, powders or fibers of copper, nickel, aluminum, silver.
  • the positive electrode membrane layer also includes a positive electrode binder.
  • the positive electrode binder can be selected from those known in the art that can be used as the positive electrode membrane layer.
  • the positive electrode binder is such as but not limited to polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, Ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (esterified) styrene-butadiene rubber, epoxy resin, nylon.
  • the preparation method of the positive electrode sheet can be a method known in the art for the preparation of the positive electrode sheet that can be used in an electrochemical device.
  • a solvent is usually added, a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent and a thickening agent are added as required, and then dissolved or dispersed in the solvent to prepare the positive electrode slurry.
  • the solvent is evaporated and removed during the drying process.
  • the solvent is known in the art and can be used as the positive electrode membrane layer, such as but not limited to N-methylpyrrolidone (NMP).
  • NMP N-methylpyrrolidone
  • the present application has no particular restrictions on the mixing ratio of the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent in the positive electrode membrane layer, and the mixing ratio can be controlled according to the desired performance of the electrochemical device.
  • the positive electrode current collector includes a blank area and a coverage area
  • the blank area is an area on the positive electrode current collector that is not covered with a positive electrode film layer
  • the coverage area is a positive electrode film covered on the positive electrode current collector slice area.
  • the roughness of the blank area is 500 mm -1 to 2000 mm -1 , which can have better electrode adhesion and improve brittleness, thereby effectively improving battery performance. In some embodiments, the roughness of the blank area is 700 mm -1 to 1500 mm -1 .
  • the surface roughness of the coverage area is too low, it means that the riveting effect between the positive electrode active material and the positive electrode current collector is relatively weak, which affects the bonding force of the pole piece to a certain extent; if the surface roughness of the coverage area is too high, it means that the positive electrode The current collector is relatively damaged during the cold pressing process, which may lead to particle crushing and crushing of the positive current collector to a certain extent, resulting in the risk of electrical performance loss and PD window loss.
  • the roughness of the coverage area is 1500 mm -1 to 8000 mm -1 , which can have better cohesion of the pole pieces and reduce the risk of particle crushing and current collector punch-through, effectively improving battery performance.
  • the roughness of the footprint is from 2000 mm" 1 to 5000 mm" 1 .
  • the roughness of the current collector can be controlled by arranging open pits on its surface, or other methods known in the art can be used for control, which can be selected by those skilled in the art according to the actual situation.
  • the roughness of the current collector can be measured by methods known in the art.
  • the roughness of the blank area and the coverage area of the positive electrode current collector can be tested by using a Japanese Mitutoyo SJ-210 roughness tester.
  • the test method for the coverage area is as follows: immerse the positive electrode piece in N-methylpyrrolidone (NMP) solution for 10 minutes, use a scraper to scrape off the positive active film layer on the surface of the positive electrode current collector, and then remove it.
  • NMP N-methylpyrrolidone
  • the negative electrode includes a negative electrode current collector and a negative electrode film layer, the negative electrode film layer is disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.
  • the negative current collector is a metal such as, but not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a conductive metal clad polymer substrate, or a combination thereof.
  • the negative electrode active material can be any material capable of intercalating and deintercalating active ions or materials capable of doping and dedoping active ions that can be used as electrochemical devices.
  • the negative active material includes at least one of carbon materials, metal alloys, lithium-containing oxides, and silicon-containing materials.
  • the carbon material is selected from graphite materials.
  • the negative active material is surface coated or uncoated.
  • the negative electrode membrane layer further includes a negative electrode binder.
  • the present application has no particular limitation on the negative electrode binder, such as but not limited to styrene-butadiene rubber (abbreviated as SBR).
  • SBR styrene-butadiene rubber
  • the preparation method of the negative electrode sheet can adopt the preparation method of the negative electrode sheet that can be used in the electrochemical device known in the art.
  • a solvent is usually added, the negative electrode active material is added with a negative electrode binder, and a conductive material and a thickener are added as required, and then dissolved or dispersed in the solvent to prepare the negative electrode slurry.
  • the solvent is evaporated and removed during the drying process.
  • the solvent is known in the art and can be used as a solvent for the anode membrane layer, such as, but not limited to, water.
  • Thickeners are known in the art that can be used as the negative electrode membrane layer, such as but not limited to sodium carboxymethylcellulose (abbreviated as CMC).
  • CMC sodium carboxymethylcellulose
  • the present application has no particular restrictions on the mixing ratio of the negative electrode active material, negative electrode binder, and thickener in the negative electrode membrane layer, and the mixing ratio can be controlled according to the desired performance of the electrochemical device.
  • a separator is provided between the positive electrode and the negative electrode to prevent short circuits.
  • the material and shape of the separator used in the electrochemical device of the present application are not particularly limited, and separators known to those skilled in the art that can be used in electrochemical devices can be used.
  • the release film comprises polyethylene (PE), ethylene-propylene copolymer, polypropylene (PP), ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-methyl methacrylate copolymer at least one of.
  • the isolation membrane is a single layer or multiple layers.
  • the electrochemical device also includes an electrolyte.
  • the type of the electrolyte is not specifically limited.
  • the electrolyte includes a lithium salt and an organic solvent.
  • the types of lithium salts and organic solvents are not specifically limited, and can be selected according to actual needs.
  • Lithium salts such as, but not limited to, lithium hexafluorophosphate (LiPF 6 ).
  • Organic solvents such as, but not limited to, carbonates, carboxylates, ethers, sulfones, or other aprotic solvents. The organic solvent can be used alone or in a mixture, and when used in a mixture, the ratio of the mixture can be controlled according to the desired performance of the electrochemical device.
  • the electrolyte further includes additives.
  • the type of the additive is not particularly limited, and it can be a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain properties of the battery, such as an additive that improves the overcharge performance of the battery, improves the high temperature of the battery. Performance additives, additives to improve battery low temperature performance, etc.
  • the additive includes an ether dinitrile compound.
  • the ether dinitrile compound can form a film on the surface of the positive electrode, improve the thermal stability of the positive electrode, and further improve the high-temperature storage performance of the electrochemical device.
  • ether dinitrile compound refers to a compound having an ether bond and two cyano groups.
  • ether dinitrile compounds include ethylene glycol bis(propionitrile) ether, diethylene glycol bis(2-cyanoethyl) ether, triethylene glycol bis(2-cyanoethyl) ether , at least one of tetraethylene glycol bis(2-cyanoethyl) ether, ethylene glycol bis(4-cyanobutyl) ether or 3,3'-oxydipropionitrile.
  • the mass percentage of the ether dinitrile compound is 0.01% to 15%. If the amount of ether dinitrile compound added is greater than the above range, it will react more with the electrolyte, which may affect the first efficiency of the cell, and it will form a thicker film on the positive electrode, which may increase the ion transfer resistance, thereby affecting the The ability of the battery to charge and discharge quickly; if the amount of the ether dinitrile compound added is less than the above range, it may not be able to effectively form a film on the positive electrode, thereby affecting the protective effect of the ether dinitrile compound. In some embodiments, based on the total mass of the electrolyte, the mass percentage of the ether dinitrile compound is less than or equal to 5%.
  • the conductivity of the electrolyte is not specifically limited. In some embodiments, the conductivity of the electrolyte is greater than or equal to 7 ms/cm. When the conductivity of the electrolyte is within the above range, it has high ionic conductivity, which can satisfy the rapid movement of lithium ions in the rapid charge and discharge technology. If the conductivity is too small, it may cause the battery to have a relatively large polarization, which affects the battery's charge and discharge performance to a certain extent.
  • the present application does not limit the method for controlling the conductivity of the electrolyte, and those skilled in the art can adjust the conductivity of the electrolyte by using methods known in the art according to the actual situation. In the present application, the conductivity of the electrolyte can be controlled by controlling the type and concentration of the added lithium salt, the viscosity and the dielectric constant of the organic solvent.
  • the electronic device of the present application is any electronic device, such as but not limited to notebook computers, pen-type computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders , LCD TV, Portable Cleaner, Portable CD Player, Mini Disc, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, Motorcycle, Power-assisted Bicycle, Bicycle, Lighting Appliances, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, lithium-ion capacitors.
  • the electrochemical device of the present application is not only applicable to the electronic devices exemplified above, but also applicable to energy storage power stations, marine vehicles, and air vehicles.
  • Airborne vehicles include airborne vehicles within the atmosphere and airborne vehicles outside the atmosphere.
  • the electronic device comprises an electrochemical device as previously described herein.
  • the lithium cobalt oxide particles with a particle size distribution of about 38 ⁇ m were screened, and the Dv99 of the lithium cobalt oxide cathode active material was tested by a Malvern 3000 laser particle sizer to be 38.2 ⁇ m.
  • the thickness D l of the positive electrode film layer is measured by a micrometer to be 30 ⁇ m; the thickness of the positive electrode sheet is 70 ⁇ m.
  • the roughness of the blank area of the current collector is 800mm -1 and the roughness of the coverage area is 2300mm -1 by the Japanese Mitutoyo SJ-210 roughness tester.
  • Graphite, styrene-butadiene rubber and sodium carboxymethyl cellulose are fully stirred and mixed in an appropriate amount of deionized water according to the weight ratio of 97.4:1.2:1.4 to form a uniform negative electrode slurry, which is coated on the current collector. On the copper foil, drying and cold pressing to obtain a negative electrode sheet.
  • the PE porous polymer film is used as the separator.
  • ethylene carbonate abbreviated as EC
  • PC propylene carbonate
  • DEC diethyl carbonate
  • EP ethyl propionate
  • PP propyl propionate
  • the positive electrode sheet, the separator, and the negative electrode sheet are wound in the order of one layer of positive electrode sheet, one layer of separator film, and one layer of negative electrode sheet to form an electrode assembly, and then encapsulated, injected with electrolyte and left to stand to obtain an electrode assembly to be fully soaked. Then, through the steps of formation and capacity, an SEI film is formed on the surface of the negative electrode, thereby activating the lithium ion battery, making it in a state of charge, and then obtaining a finished lithium ion battery.
  • the preparation method is the same as that of Example 1.
  • the difference is that some parameters of the positive electrode active material, current collector, positive electrode membrane layer, and electrolyte are adjusted in Examples 2 to 19. Please refer to Table 1 for specific parameters.
  • Example 20 Consistent with the preparation method of Example 1, the difference is that in Example 20, the mass percentage of ether dinitrile in the electrolyte is 13%, the conductivity of the electrolyte is 12 mS/cm, and the preparation of the positive electrode:
  • the small-sized lithium cobalt oxide particles are screened out, and after sintering, the jet mill is used for crushing to obtain lithium cobalt oxide secondary particles with a particle size distribution of about 18 ⁇ m;
  • the particles were sufficiently mixed at a mass ratio of 5:5 to obtain a positive electrode active material including primary particles and secondary particles.
  • the Dv99 of the cathode active material was measured by a Malvern 3000 laser particle sizer to be 18 ⁇ m.
  • the thickness D l of the positive electrode film layer is measured by a micrometer to be 20 ⁇ m; the thickness of the positive electrode film is 50 ⁇ m.
  • the roughness of the blank area of the current collector is 1300mm -1 and the roughness of the coverage area is 3800mm -1 by the Japanese Mitutoyo SJ-210 roughness tester.
  • the preparation method is the same as that of Example 20.
  • the difference is that some parameters of the positive electrode active material, current collector, positive electrode membrane layer, and electrolyte are adjusted in Examples 21 to 26. Please refer to Table 1 for specific parameters.
  • Example 27 Consistent with the preparation method of Example 1, the difference is that in Example 27, the mass percentage of ether dinitrile in the electrolyte is 1%, the conductivity of the electrolyte is 9.8 mS/cm, and the preparation of the positive electrode:
  • lithium cobalt oxide particles are screened out, and after sintering, the jet mill is used to crush them to obtain lithium cobalt oxide secondary particles with a particle size distribution of about 18 ⁇ m;
  • the Dv99 of the sub-particle positive active material was 17.6 ⁇ m.
  • the thickness D l of the positive electrode film layer is measured by a micrometer to be 23.5 ⁇ m; the thickness of the positive electrode film is 55 ⁇ m.
  • the roughness of the blank area of the current collector is 800mm -1 and the roughness of the coverage area is 5700mm -1 by the Japanese Mitutoyo SJ-210 roughness tester.
  • the preparation method is the same as that of Example 27, except that some parameters of the positive electrode active material, current collector, positive electrode membrane layer, and electrolyte are adjusted in Examples 28 to 36. Please refer to Table 2 for specific parameters.
  • the preparation method is the same as that of Example 20, except that in Comparative Example 2, the thickness D l of the positive electrode film layer is 7.5 ⁇ m; the thickness of the positive electrode film layer is 25 ⁇ m; the compaction density of the positive electrode film layer is 4.15 g/dm 3 .
  • the preparation method is the same as that of Example 24, except that in Comparative Example 3, the thickness D l of the positive electrode film layer is 5 ⁇ m; the thickness of the positive electrode film layer is 20 ⁇ m; the compaction density of the positive electrode film layer is 4.15 g/dm 3 .
  • the roughness of the blank area of the current collector is 900mm -1 and the roughness of the coverage area is 6300mm -1 by the Japanese Mitutoyo SJ-210 roughness tester.
  • the difference is that the Dv99 of the positive electrode active material in Comparative Example 4 is 25 ⁇ m; the thickness D c of the aluminum foil is 12 ⁇ m; the thickness D l of the positive film layer is 24 ⁇ m; the thickness of the positive electrode sheet is 60 ⁇ m.
  • the preparation method is the same as that of Example 26, except that the Dv99 of the positive electrode active material in Comparative Example 5 is 17 ⁇ m; the thickness D c of the aluminum foil is 9 ⁇ m; the thickness D l of the positive film layer is 18 ⁇ m; the thickness of the positive electrode sheet is 45 ⁇ m; The compaction density of the positive electrode membrane layer was 3.8 g/dm 3 .
  • the primary particles used in Examples 1-36 and Comparative Examples 1-5 can also be obtained directly from commercial sources in addition to the methods described in the Examples and Comparative Examples of the present application; in Example 1
  • the secondary particles used in -36 and Comparative Examples 1-5, in addition to being obtained by sintering the primary particles according to the methods described in the Examples and Comparative Examples of the present application, can also be directly obtained commercially.
  • Lithium-ion battery performance test method
  • Thickness expansion ratio (%) (dd 0 )/d 0 ⁇ 100% after high temperature storage at 85°C for 6 hours.
  • the lithium-ion battery was discharged to 3.0V at 1.0C, left for 5 minutes, then charged to 4.48V at a current of 0.7C, and then charged to 0.025C at a constant voltage, and allowed to stand for 5 minutes. Taking the above process as one cycle, the fourth discharge capacity was recorded as 100%, and the number of cycles when the discharge capacity was 80% was recorded.
  • Comparing the data of Comparative Example 5 and Example 26 it can be obtained that, when the positive electrode active material includes primary particles and secondary particles and the mass ratio of the primary particles is less than 20%, if the thickness of the positive electrode membrane layer is less than 1.1 times that of the positive electrode active material particles If the particle size is Dv99, the particles are prone to appearance problems such as particle scratches and bumps during coating, and deteriorate the high-temperature storage performance and high-temperature cycle performance of the lithium-ion battery.
  • Example 11 Comparing the data of Examples 7 to 8 and Examples 11 to 12, it can be seen that the roughness of the blank area of the positive electrode current collector and the roughness of the coverage area are too high or too low, which will affect the appearance of the pole piece and the high temperature storage of the lithium ion battery. performance and high temperature cycling performance.
  • the roughness of the blank area of the current collector is lower than 500 mm -1
  • the roughness of the coverage area is lower than 1500 mm -1
  • the appearance of the pole piece is poor
  • the thickness expansion rate after high temperature storage at 85 °C is relatively large
  • the thickness expansion rate after high temperature storage at 85 °C is relatively large.
  • Example 12 When the discharge capacity is 80%, the number of cycles decreases; in Example 12, the roughness of the blank area of the current collector is higher than 2000mm -1 , the roughness of the coverage area is higher than 8000mm -1 , and the pole piece is prone to particle scratches and bumps and other appearance problems, and the thickness expansion rate after high temperature storage at 85 °C is relatively large, and the number of cycles when the discharge capacity is 80% at 45 °C is reduced.
  • Example 13 Comparing the data of Example 8 and Examples 13 to 14, it can be seen that the ether dinitrile additive affects the storage and high temperature cycling performance of the lithium ion battery.
  • no ether dinitrile additive was added, the thickness expansion rate after high temperature storage at 85°C was relatively large, and the cycle times decreased when the discharge capacity at 45°C was 80%; in Example 14, excessive ether dinitrile additive was added, The thickness expansion rate after high-temperature storage at 85°C is relatively large, and the cycle number decreases when the discharge capacity is 80% at 45°C.
  • Example 15 Comparing the data of Example 10 and Example 15, it can be seen that the electrical conductivity of the electrolyte affects the high temperature cycle performance of the lithium ion battery.
  • the conductivity of the electrolyte solution was less than 7 ms/cm, and the number of cycles when the discharge capacity at 45°C was 80% was reduced.
  • Example 10 Comparing the data of Example 10 and Examples 16 to 17, it can be found that the thickness of the positive electrode membrane layer and the thickness of the positive electrode current collector affect the appearance of the electrode and the high temperature cycle performance. Comparing the data of Examples 10, 16, 18 and 19, it can be found that the compaction density of the positive membrane layer affects the high temperature storage and high temperature cycling performance of the lithium ion battery.
  • the particle size Dv99 of the positive electrode active material affects the high temperature cycle performance of the lithium ion battery
  • the particle size Dv99 of the positive electrode active material is less than 5 ⁇ m or greater than 48 ⁇ m
  • the discharge capacity at 45°C is 80%. The number of cycles is reduced.

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Abstract

提供一种电化学装置和电子装置。电化学装置包括正极，正极包括集流体（2）和包括正极活性材料的膜片层，膜片层设置在集流体的至少一个表面上，正极活性材料包括一次颗粒和/或二次颗粒（1）；当正极活性材料中的一次颗粒（1）基于正极活性材料的质量百分含量A满足20％≤A≤100％时，膜片层、正极活性材料、集流体（2）之间满足：Dl≥Dv99-Dc；当正极活性材料中的一次颗粒（1）基于正极活性材料的质量百分含量A'满足0≤A'＜20％，膜片层、正极活性材料、集流体（2）之间满足：Dl≥1.1Dv99。电子装置包括电化学装置。电化学装置能够改善极片外观并兼具快充电性能、存储性能和循环性能。

Description

电化学装置和电子装置 技术领域
本申请涉及一种电化学装置和电子装置。
背景技术
电化学装置，例如锂离子电池，具有高能量密度、低维护、自放电率低、工作温度范围宽、长循环寿命、无记忆效应、工作电压稳定和环境友好等特性被广泛用于智能产品(包括手机、笔记本、相机等电子产品)、电动工具和电动汽车等领域。随着技术的快速发展以及市场需求的多样性，人们对电化学装置的性能提出了更高的要求，例如快充性能。
然而，在提高锂离子电池快充性能的时候，锂离子电池的其他性能，例如存储性能、循环性能，却下降了，为此，急需一种在提高锂离子电池快充性能的同时不降低其存储性能、循环性能的技术方案。
发明内容
在一些实施例中，本申请提供了一种电化学装置，包括正极，所述正极包括集流体和包括正极活性材料的膜片层，所述膜片层设置在所述集流体的至少一个表面上，所述正极活性材料包括一次颗粒和/或二次颗粒；当所述正极活性材料中的一次颗粒基于正极活性材料的质量百分含量A满足20％≤A≤100％时，所述膜片层、正极活性材料、集流体之间满足：D l≥Dv99-D c；当所述正极活性材料中的一次颗粒基于正极活性材料的质量百分含量A’满足0≤A’＜20％，所述膜片层、正极活性材料、集流体之间满足：D l≥1.1Dv99；其中，D l为膜片层的厚度，D c为集流体的厚度，Dv99为正极活性材料累计体积百分数达到99％时所对应的粒径。
在一些实施例中，所述膜片层厚度D l与所述集流体厚度D c关系满足：0.05≤D l/D c≤3.75。
在一些实施例中，所述膜片层的厚度D l为1μm至30μm。
在一些实施例中，所述集流体的厚度D c为4μm至20μm。
在一些实施例中，所述正极活性材料的粒径Dv99为5μm至48μm。
在一些实施例中，所述膜片层的压实密度为2g/dm 3至4.3g/dm 3。
在一些实施例中，所述集流体包括空白区和覆盖区；所述空白区为所述集流体上未覆盖膜片层的区域，所述空白区的粗糙度为500mm -1至2000mm -1；所述覆盖区为所述集流体上覆盖膜片层的区域，所述覆盖区的粗糙度为1500mm -1至8000mm -1。
在一些实施例中，所述电化学装置还包括电解液，所述电解液包括醚二腈化合物；基于电解液的总质量，所述醚二腈化合物的质量百分含量为0.01％至15％。
在一些实施例中，所述电解液的电导率大于等于7mS/cm。
在一些实施例中，本申请还提供了一种电子装置，所述电子装置包括本申请前述的电化学装置。
本申请的技术方案至少具有以下有益的效果：本申请同时考虑了一次颗粒和二次颗粒的不同的结构特征，并且将正极膜片层、正极活性材料和正极集流体的尺寸设计为满足特定的关系，当其适用于快充电池中，能够最大限度地避免快充电池使用过程中的风险，不容易在冷压时出现被颗粒压碎的情形，可改善极片外观并兼具快充电性能、存储性能和循环性能。
附图说明
图1为当正极活性材料为一次颗粒时，经冷压后一次颗粒与集流体之间的位置关系示意图；
图2为当正极活性材料为二次颗粒时，经冷压后二次颗粒与集流体之间的位置关系示意图；
其中，附图标记为：1-正极活性材料颗粒，2-正极集流体。
具体实施方式
下面详细充分地说明示例性实施例，不过，这些示例性实施例可以用不同的方式来实施，并且，不应被解释为局限于本申请所阐述的这些实施例。相反，提供这些实施例的目的在于使本申请公开彻底和完整，以及将本申请的范围充分地传达给本领域所属技术人员。
(电化学装置)
本申请的电化学装置例如为一次电池、二次电池、燃料电池、太阳能电池或电容器。二次电池例如为锂二次电池，锂二次电池包含但不限于锂金属二次电池、锂离子二次电池、 锂聚合物二次电池或锂离子聚合物二次电池。
在一些实施例中，电化学装置包含正极、负极和隔离膜。
[正极]
正极包括正极集流体和正极膜片层，所述正极膜片层设置在所述正极集流体的至少一个表面上，所述正极膜片层包括正极活性材料，所述正极活性材料包括一次颗粒和/或二次颗粒。
在本申请中，术语“一次颗粒”为单一晶粒的活性材料颗粒，两个及以上的一次颗粒可通过聚集形成二次颗粒。在一些实施例中，所述一次颗粒可具有多种形状的任一种，包括棒状和矩形、或其组合。术语“二次颗粒”为由两个及以上的一次颗粒聚集而形成，并且不再进一步与其它颗粒聚集。一次颗粒和二次颗粒分别具有各自独立的结构特征。在本申请中，一次颗粒可以通过将相对较小颗粒过烧结获得，二次颗粒可以通过使一次颗粒凝聚获得。
在一些实施例中，所述正极活性材料包括一次颗粒，一次颗粒基于正极活性材料的质量百分含量为100％，所述正极膜片层、正极活性材料、正极集流体之间满足：D l≥Dv99-D c；其中，D l为正极膜片层的厚度；D c为正极集流体的厚度；Dv99为正极活性材料累计体积百分数达到99％时所对应的粒径。
如图1所示，一次颗粒为单一晶粒的正极活性材料颗粒1且一般为非正球形，颗粒间摩擦力较小，在制备正极片的过程中受到冷压辊压时容易左右偏移并发生相对滑移而压缩正极集流体2。在一些实施例中，正极集流体为金属箔。金属箔例如包括但不限于铜箔、铝箔。在一些实施例中，正极集流体为铝箔。
当正极活性材料中仅存在一次颗粒时，如果正极膜片层的厚度和正极集流体厚度之和小于正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，冷压辊压时也极易出现颗粒被压碎的情形，造成极片外观不良，并容易导致制作的电芯出现高温存储胀气、循环加速等问题。
在一些实施例中，所述正极活性材料颗粒仅包括二次颗粒，一次颗粒基于正极活性材料的质量百分含量为0％，所述正极膜片层和正极活性材料之间满足：D l≥1.1Dv99。
如图2所示，二次颗粒为由两个及以上的一次颗粒聚集而形成，颗粒间摩擦力较大，在制备正极片的过程中受到冷压辊压时不容易产生相对滑移，因此正极活性材料颗粒1不会压缩正极集流体2。
当正极活性材料中仅存在二次颗粒时，由于二次颗粒的特殊的结构特征，因此在设计正极膜片层和正极活性材料颗粒的尺寸关系时，按二次颗粒的1.1倍的Dv99作为设计尺寸，如果正极膜片层的厚度小于1.1倍的正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，冷压辊压时也极易出现颗粒被压碎的情形，造成极片外观不良，并容易导致制作的电芯出现高温存储胀气、循环加速等问题。
在一些实施例中，所述正极活性材料包括一次颗粒和二次颗粒，且一次颗粒基于正极活性材料的质量百分含量大于等于20％，所述正极膜片层、正极活性材料、正极集流体之间满足：D l≥Dv99-D c。当正极活性材料中既存在一次颗粒又存在二次颗粒时，如果一次颗粒的质量百分含量大于等于前述范围时，此时一次颗粒能够很好地分布在二次颗粒中，有效地阻止二次颗粒之间的接触，起到润滑作用，其类似于正极活性材料仅包括一次颗粒的情况，此时，如果正极膜片层的厚度和正极集流体厚度之和小于正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，冷压辊压时也极易出现颗粒被压碎的情形，造成极片外观不良，并容易导致制作的电芯出现高温存储胀气、循环加速等问题。在一些实施例中，所述正极活性材料包括一次颗粒和二次颗粒，且一次颗粒基于正极活性材料的质量百分含量大于或等于40％。
在一些实施例中，正极活性材料包括一次颗粒和二次颗粒，且一次颗粒基于正极活性材料的质量百分含量小于20％，所述正极膜片层、正极活性材料、正极集流体之间满足：D l≥1.1Dv99。当正极活性材料中既存在一次颗粒又存在二次颗粒时，如果一次颗粒的质量百分含量小于前述范围时，此时一次颗粒无法充分阻碍二次颗粒间的接触，二次颗粒间的滑移难度增加，其类似于正极活性材料仅包括二次颗粒的情况，此时，如果正极膜片层的厚度小于1.1倍的正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，冷压辊压时也极易出现颗粒被压碎的情形，造成极片外观不良，并容易导致制作的电芯出现高温存储胀气、循环加速等问题。在一些实施例中，所述正极活性材料包括一次颗粒和二次颗粒，且一次颗粒基于正极活性材料的质量百分含量小于等于10％。
快速充放电技术，是指电池使用超过1C倍率的充放电的技术。当使用快速充放电技术对电池进行充电时能够实现电池的快速充电，并且对电池无损伤，不影响使用寿命。但是，快速充放电技术需要电池具有大倍率充电的功能，因此需要降低电芯的离子极化以实现其大倍率充电的功能。发明人发现，薄电极设计的电池能够缩短锂离子传输路径，从而降低电芯的离子极化；然而，在薄电极设计的电池中，如果主材尺寸设计不合理，则容易在冷压时出现被颗粒压碎的情形，进而影响极片外观、电池性能。
在本申请的电化学装置中，设计正极时，同时考虑了一次颗粒和二次颗粒的不同的结构特征，并且将正极膜片层、正极活性材料和正极集流体的尺寸设计为满足特定的关系，当其适用于快充电池中，能够最大限度地避免快充电池使用过程中的风险，不容易在冷压时出现被颗粒压碎的情形，可改善极片外观并提升电池性能，能够兼具快充电性能、存储性能和循环性能。
在本申请的一些实施例中，薄电极对应正极集流体单侧的正极膜片层的厚度的上限为30μm。在一些实施例中，正极膜片层的厚度D l为1μm至30μm。具备这种膜片层厚度的正极片，说明其相应地具有较薄的电极设计，能够更好地缩短锂离子传输路径，并降低电芯的离子极化，当与本申请的正极集流体、正极活性材料尺寸配合时，能够兼具更好的快充电性能、存储性能和循环性能。
在一些实施例中，正极集流体的厚度D c为4μm至20μm。
在一些实施例中，正极膜片层的厚度D l与正极集流体的厚度D c关系满足：0.05≤D l/D c≤3.75。正极膜片层和正极集流体的厚度比在上述范围内，能够减小安全风险；如果比值过小，则正极膜片层的厚度相对较小，可能会增加极片制作时出现划痕露金属的几率；如果比值过大，则正极膜片层的厚度相对较大且正极集流体的厚度相对较小，可能会增加极片冷压绕卷时出现内圈脆断的几率。在一些实施例中，正极膜片层的厚度D l与正极集流体的厚度D c关系满足：0.3≤D l/D c≤3.1。
正极活性材料的粒径大小影响正极活性材料颗粒在正极膜片层中的固相扩散阻抗，进而影响电池性能。在一些实施例中，正极活性材料的粒径Dv99为5μm至48μm。如果正极活性材料的粒径过大，则其固相扩散阻抗会相应地较大，造成电池充放电极化相对较大，进而影响循环性能。在一些实施例中，正极活性材料的粒径Dv99为20μm至40μm。
在一些实施例中，正极膜片层的压实密度为2g/dm 3至4.3g/dm 3。
在本申请中，正极膜片层、正极集流体和正极活性材料的各参数可按如下方法进行测试，也可按照本领域其它公知的方法进行测试，得到的测试结果均在误差范围内：
正极活性材料的Dv99可通过马尔文3000激光粒度仪进行测试，测试三次取平均值即为测试结果。
正极集流体的厚度D c可通过使用万分尺进行测试，在正极集流体的表面均匀地取五个点并进行测试，取五个测试值的平均值即为测试结果。
正极膜片层的厚度D l即为正极片冷压后集流体单侧的膜片层厚度。当正极膜片层设置在正极集流体的一侧表面上时，正极膜片层的厚度＝正极片的厚度-正极集流体的厚度；当 正极膜片层设置在正极集流体的两侧表面上时，正极膜片层的厚度＝(正极片的厚度-正极集流体的厚度)/2。其中，正极片的厚度可通过使用万分尺进行测试，在正极片的表面均匀地取五个点并进行测试，取五个测试值的平均值为测试结果。
正极膜片层的压实密度＝正极膜片层的质量/正极膜片层的面积/正极膜片层的厚度。
正极活性材料可选用本领域技术公知的各种可被用作电化学装置的能够可逆地嵌入、脱嵌活性离子的传统公知的材料。在一些实施例中，正极活性材料包括钴酸锂、锰酸锂、镍钴锰酸锂(NCM)、镍钴铝酸锂(NCA)中的至少一种。
正极膜片层还包括正极导电剂。正极导电剂可选用本领域公知的可被用作正极膜片层的导电剂。在本申请中，正极导电剂包括但不限于天然石墨、人造石墨、导电炭黑、乙炔黑、科琴黑、碳纤维、聚亚苯基衍生物、金属粉、金属纤维，其中，金属粉和金属纤维例如但不限于铜、镍、铝、银的粉或纤维。
正极膜片层还包括正极粘结剂。正极粘结剂可选用本领域公知的可被用作正极膜片层的粘结剂。在本申请中，正极粘结剂例如但不限于聚乙烯醇、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、尼龙。
正极片的制备方法可采用本领域技术公知的可被用于电化学装置的正极片的制备方法。在一些实施例中，在正极浆料的制备中，通常加入溶剂，正极活性材料、正极粘结剂并根据需要加入正极导电剂和增稠剂后溶解或分散于溶剂中制成正极浆料。溶剂在干燥过程中挥发去除。溶剂是本领域公知的可被用作正极膜片层的溶剂，溶剂例如但不限于N-甲基吡咯烷酮(NMP)。本申请对于正极膜片层中的正极活性材料、正极粘结剂、正极导电剂的混合比例没有特别的限制，可以根据期望的电化学装置性能控制其混合比例。
在一些实施例中，正极集流体包括空白区和覆盖区，所述空白区为所述正极集流体上未覆盖正极膜片层的区域，所述覆盖区为所述正极集流体上覆盖正极膜片层的区域。
如果空白区的表面粗糙度过低，则粘结剂与正极集流体之间接触点相对变少，影响正极片的初始粘结力，在极片覆盖后会出现一定程度的脱模问题；如果空白区的表面粗糙度过高，则说明正极集流体缺陷相对较多，力学性能可能会有一定程度的损失，影响极片脆性。在一些实施例中，空白区的粗糙度为500mm -1至2000mm -1，可以具有较好的极片粘结力并改善脆性，有效改善电池性能。在一些实施例中，空白区的粗糙度为700mm -1至1500mm -1。
如果覆盖区的表面粗糙度过低，则说明正极活性材料与正极集流体铆合作用相对较弱，在一定程度上影响极片粘结力；如果覆盖区的表面粗糙度过高，则说明正极集流体在冷压过程中受到了相对较大的破坏，在一定程度上可能会导致颗粒压碎以及正极集流体压穿，进而造成电性能损失及P.D.窗口损失的风险。在一些实施例中，覆盖区的粗糙度为1500mm -1至8000mm -1，可以具有较好的极片粘结力并减小颗粒压碎以及集流体压穿风险，有效改善电池性能。在一些实施例中，覆盖区的粗糙度为2000mm -1至5000mm -1。
在本申请中，集流体的粗糙度可以通过在其表面设置开放凹坑控制，也可以采用本领域公知的其他方法进行控制，本领域技术人员可以根据实际情况选用。在本申请中，集流体的粗糙度可采用本领域公知的方法测定，例如，正极集流体的空白区和覆盖区的粗糙度均可通过使用日本三丰SJ-210粗糙度测试仪进行测试。在一些实施例中，覆盖区的测试方法为：将正极极片浸泡于N-甲基吡咯烷酮(NMP)溶液中10min，取出后使用刮板刮去正极集流体表面的正极活性膜片层，然后使用干净的NMP再次冲洗正极集流体表面，使正极集流体表面无异物，最后将正极集流体置于烘箱内85℃烘干后，取出使用日本三丰SJ-210粗糙度测试仪测试粗糙度值即为覆盖区的粗糙度。
[负极]
负极包括负极集流体和负极膜片层，所述负极膜片层设置在所述负极集流体的至少一个表面上，所述负极膜片层包括负极活性材料。在一些实施例中，负极集流体为金属，例如但不限于铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、包覆有导电金属的聚合物基板或它们的组合。
负极活性材料可选用任何可被用作电化学装置的能够嵌入、脱嵌活性离子的材料或能够掺杂、脱掺杂活性离子的材料。在一些实施例中，负极活性材料包括碳材料、金属合金、含锂氧化物及含硅材料中的至少一种。在一些实施例中，碳材料选自石墨材料。在一些实施例中，负极活性材料为表面包覆的或不包覆的。
负极膜片层还包括负极粘结剂。本申请对负极粘结剂没有特别的限制，例如但不限于丁苯橡胶(简写为SBR)。负极片的制备方法可采用本领域技术公知的可被用于电化学装置的负极片的制备方法。在一些实施例中，在负极浆料的制备中，通常加入溶剂，负极活性材料加入负极粘结剂并根据需要加入导电材料和增稠剂后溶解或分散于溶剂中制成负极浆料。溶剂在干燥过程中挥发去除。溶剂是本领域公知的可被用作负极膜片层的溶剂，溶剂例如但不限于水。增稠剂是本领域公知的可被用作负极膜片 层的增稠剂，增稠剂例如但不限于羧甲基纤维素钠(简写为CMC)。本申请对于负极膜片层中的负极活性材料、负极粘结剂、增稠剂的混合比例没有特别的限制，可以根据期望的电化学装置性能控制其混合比例。
[隔离膜]
在本申请的一些实施例中，在正极与负极之间设有隔离膜以防止短路。本申请的电化学装置中使用的隔离膜的材料和形状没有特别限制，可以使用本领域技术公知的可被用于电化学装置的隔离膜。在一些实施例中，隔离膜包含聚乙烯(PE)、乙烯-丙烯共聚物、聚丙烯(PP)、乙烯-丁烯共聚物、乙烯-己烯共聚、乙烯-甲基丙烯酸甲酯共聚物中的至少一种。在一些实施例中，隔离膜为单层或多层。
[电解液]
电化学装置还包括电解液。在本申请中，所述电解液的种类并不受到具体的限制。
在一些实施例中，电解液包括锂盐以及有机溶剂。锂盐以及有机溶剂的种类均不受到具体的限制，可根据实际需求进行选择。锂盐例如但不限于六氟磷酸锂(LiPF 6)。有机溶剂例如但不限于碳酸酯类、羧酸酯类、醚类、砜类或其他非质子溶剂。有机溶剂可以单独使用或以混合物使用，当以混合物使用时，可以根据期望的电化学装置性能控制混合物的比例。
在一些实施例中，电解液还包括添加剂。所述添加剂的种类也没有特别的限制，可以为负极成膜添加剂，也可为正极成膜添加剂，也可以为能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
在一些实施例中，添加剂包括醚二腈化合物。醚二腈化合物能够在正极表面成膜，提高正极热稳定性，进一步改善电化学装置的高温存储性能。
术语“醚二腈化合物”表示具有醚键和两个氰基的化合物。在一些实施例中，醚二腈化合物包括乙二醇双(丙腈)醚、二乙二醇二(2-氰基乙基)醚、三乙二醇二(2-氰基乙基)醚、四乙二醇二(2-氰基乙基)醚、乙二醇二(4-氰基丁基)醚或3,3'-氧二丙腈中的至少一种。
在一些实施例中，基于电解液的总质量，所述醚二腈化合物的质量百分含量为0.01％至15％。如果醚二腈化合物的添加量大于上述范围，则其与电解液的反应较多，可能会影响电芯首效，并且其在正极会形成较厚的膜，可能会增加离子转移阻抗，进而影响电芯快 速充放电的能力；若果醚二腈化合物的添加量小于上述范围，则其可能无法在正极有效地成膜，进而影响醚二腈化合物的保护作用的发挥。在一些实施例中，基于电解液的总质量，所述醚二腈化合物的质量百分含量小于等于5％。
在本申请中，所述电解液的电导率并不受到具体的限制。在一些实施例中，所述电解液的电导率大于等于7ms/cm。当电解液的电导率位于上述范围内时，具有较高的离子电导，能够满足快速充放电技术中锂离子的快速运动。如果电导率过小，则可能会导致电池具有相对较大的极化，在一定程度上影响电池的充放电性能。本申请不限定电解液电导率的控制方法，本领域技术人员可以根据实际情况选用本领域公知的方法来调节电解液的电导率。在本申请中，电解液的电导率可以通过控制加入的锂盐种类和浓度、有机溶剂的黏度和介电常数控制电解液的电导率。
(电子装置)
本申请的电子装置是任何电子装置，例如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、锂离子电容器。注意的是，本申请的电化学装置除了适用于上述例举的电子装置外，还适用于储能电站、海运运载工具、空运运载工具。空运运载装置包含在大气层内的空运运载装置和大气层外的空运运载装置。
在一些实施例中，电子装置包含本申请前述的电化学装置。
下面结合实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。在本申请的下述具体实施例中，仅示出电池为锂离子电池的实施例，但本申请不限于此。在下述实施例、对比例中，所使用到的试剂、材料以及仪器如没有特殊的说明，均可商购获得或合成获得。
实施例1
正极的制备
执行粉磨工艺后筛选粒径分布在38μm左右的钴酸锂颗粒，通过马尔文3000激光粒度 仪测试钴酸锂正极活性材料的Dv99为38.2μm。
将正极活性材料、聚偏二氟乙烯、导电炭黑(SP)按照97：1.5：1.5的重量比在适量的NMP中充分搅拌混合，使其形成均匀的正极浆料，将此浆料涂覆于集流体铝箔(厚度D c＝10μm)上，烘干、冷压，得到正极片，测试正极膜片层的压实密度为4.15g/dm 3。
通过万分尺测试正极膜片层的厚度D l为30μm；正极片的厚度为70μm。通过日本三丰SJ-210粗糙度测试仪测试集流体空白区的粗糙度为800mm -1，覆盖区的粗糙度为2300mm -1。
负极的制备
将石墨、丁苯橡胶、羧甲基纤维素钠按照97.4：1.2：1.4的重量比在适量的去离子水中充分搅拌混合，使其形成均匀的负极浆料，将此浆料涂覆于集流体铜箔上，烘干、冷压，得到负极片。
隔离膜的制备
以PE多孔聚合薄膜作为隔离膜。
电解液的制备
在含水量<10ppm的氩气气氛手套箱中，将有机溶剂碳酸乙烯酯(简写为EC)、碳酸丙烯酯(简写为PC)、碳酸二乙酯(简写为DEC)、丙酸乙酯(简写为EP)和丙酸丙酯(简写为PP)按照1:1:1:1:1的质量比混合均匀，再将适量充分干燥的锂盐LiPF 6溶解于上述有机溶剂中，最后加入占电解液总质量5％的醚二腈(3,3'-氧二丙腈)。通过电导率仪测试电解液的电导率为10mS/cm。
锂离子电池的制备
将正极片、隔离膜、负极片按照一层正极片、一层隔离膜、一层负极片的顺序卷绕制成电极组件，再经过封装、注入电解液静置得到待浸润充分的电极组件，然后经过化成及容量步骤，使得负极表面形成SEI膜，从而激活锂离子电池，使其处于荷电状态，进而得到成品锂离子电池。
实施例2至实施例19
与实施例1的制备方法一致，不同的地方是实施例2至实施例19中调整了正极活性材料、集流体、正极膜片层、电解液的一些参数，具体参数请见表1。
实施例20
与实施例1的制备方法一致，不同的地方是实施例20中电解液中醚二腈的质量百分含量为13％，电解液的电导率为12mS/cm，以及正极的制备：
执行粉磨工艺后筛选出小粒径的钴酸锂颗粒，烧结后使用气流磨破碎，获得粒径分布在18μm左右的钴酸锂二次颗粒；将粒径分布在18μm左右二次颗粒与一次颗粒按照质量比为5：5充分混合，得到包括一次颗粒和二次颗粒的正极活性材料。通过马尔文3000激光粒度仪测试正极活性材料的Dv99为18μm。
将正极活性材料、聚偏二氟乙烯、导电炭黑(SP)按照97：1.5：1.5的重量比在适量的NMP中充分搅拌混合，使其形成均匀的正极浆料，将此浆料涂覆于集流体铝箔(厚度D c＝10μm)上，烘干、冷压，得到正极片，测试正极膜片层的压实密度为3.5g/dm 3。。
通过万分尺测试正极膜片层的厚度D l为20μm；正极片的厚度为50μm。通过日本三丰SJ-210粗糙度测试仪测试集流体空白区的粗糙度为1300mm -1，覆盖区的粗糙度为3800mm -1。
实施例21至实施例26
与实施例20的制备方法一致，不同的地方是实施例21至实施例26中调整了正极活性材料、集流体、正极膜片层、电解液的一些参数，具体参数请见表1。
实施例27
与实施例1的制备方法一致，不同的地方是实施例27中电解液中醚二腈的质量百分含量为1％，电解液的电导率为9.8mS/cm，以及正极的制备：
执行粉磨工艺后筛选出小粒径的钴酸锂颗粒，烧结后使用气流磨破碎，获得粒径分布在18μm左右的钴酸锂二次颗粒；通过马尔文3000激光粒度仪测试钴酸锂二次颗粒正极活性材料的Dv99为17.6μm。
将正极活性材料、聚偏二氟乙烯、导电炭黑(SP)按照97：1.5：1.5的重量比在适量的NMP中充分搅拌混合，使其形成均匀的正极浆料，将此浆料涂覆于集流体铝箔(厚度D c＝8μm)上，烘干、冷压，得到正极片，测试正极膜片层的压实密度为4.15g/dm 3。。
通过万分尺测试正极膜片层的厚度D l为23.5μm；正极片的厚度为55μm。通过日本三丰SJ-210粗糙度测试仪测试集流体空白区的粗糙度为800mm -1，覆盖区的粗糙度为5700mm -1。
实施例28至实施例36
与实施例27的制备方法一致，不同的地方是实施例28至实施例36中调整了正极活性材料、集流体、正极膜片层、电解液的一些参数，具体参数请见表2。
对比例1
与实施例1的制备方法一致，不同的地方是对比例1中正极活性材料的Dv99为45μm。
对比例2
与实施例20的制备方法一致，不同的地方是对比例2中正极膜片层的厚度D l为7.5μm；正极片的厚度为25μm；正极膜片层的压实密度为4.15g/dm 3。
对比例3
与实施例24的制备方法一致，不同的地方是对比例3中正极膜片层的厚度D l为5μm；正极片的厚度为20μm；正极膜片层的压实密度为4.15g/dm 3。通过日本三丰SJ-210粗糙度测试仪测试集流体空白区的粗糙度为900mm -1，覆盖区的粗糙度为6300mm -1。
对比例4
与实施例27的制备方法一致，不同的地方是对比例4中正极活性材料的Dv99为25μm；铝箔厚度D c为12μm；正极膜片层的厚度D l为24μm；正极片的厚度为60μm。
对比例5
与实施例26的制备方法一致，不同的地方是对比例5中正极活性材料的Dv99为17μm；铝箔厚度D c为9μm；正极膜片层的厚度D l为18μm；正极片的厚度为45μm；正极膜片层的压实密度为3.8g/dm 3。
需要说明的是，在实施例1-36和对比例1-5中使用的一次颗粒除了可以按照本申请实施例和对比例中所述的方法获得，也可以直接商购获得；在实施例1-36和对比例1-5中使用的二次颗粒，除了可以按照本申请实施例和对比例中所述的方法由一次颗粒烧结获得，也可以直接商购获得。
锂离子电池的性能测试方法：
85℃存储性能测试
将锂离子电池在25℃下以0.5C恒流充电至4.48V，然后恒压充电至电流为0.025C，测试此时锂离子电池的厚度并记为d 0；之后将锂离子电池放置到85℃烘箱当中，存储6h后取出，测试此时锂离子电池的厚度并记为d(趁热测试)。
85℃高温存储6h后的厚度膨胀率(％)＝(d-d 0)/d 0×100％。
(如果厚度膨胀率大于10％则不达标)
45℃循环性能测试
在45℃条件下，将锂离子电池以1.0C放电至3.0V，静置5分钟，然后以0.7C的电流充电至4.48V，再恒压充电至0.025C，静置5分钟。以上述过程作为一个循环，将第四次放电容量记为100％，记录放电容量为80％时循环的次数。
正极片外观测试
观察制备的正极片的外观，并按照以下标准分类：
如果外观无划痕、凸点等异常现象，则记为优；
如果外观划痕小于1处，且不露金属或凸点≤3处，则记为良；
如果外观划痕大于1处或凸点＞3处，则记为差。
Figure PCTCN2021077397-appb-000001
Figure PCTCN2021077397-appb-000002
由表1和表2的数据分析可以得到，当正极活性材料中的一次颗粒基于正极活性材料的质量百分含量满足大于等于20％且小于等于100％，正极膜片层Dl、正极活性材料Dv99、正极集流体Dc之间满足Dl≥Dv99-Dc时；或者当正极活性材料中的一次颗粒基于正极活性材料的质量百分含量满足大于等于0％小于20％，正极膜片层、正极活性材料、正极集流体之间满足：Dl≥1.1Dv99时；此时，制备得到的正极片具有较好的外观，制备得到的锂离子电池具有较好的高温存储性能和高温循环性能。
比较对比例1和实施例1的数据可以得到，当正极活性材料仅包括一次颗粒时，如果正极膜片层的厚度和集流体铝箔的厚度之和小于正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，且恶化锂离子电池的高温存储性能和高温循环性能。
比较对比例2和实施例20以及对比例3和实施例24的数据可以得到，正极活性材料包括一次颗粒和二次颗粒并且一次颗粒的质量占比大于等于20％时，如果正极膜片层的厚度和集流体铝箔的厚度之和小于正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，且恶化锂离子电池的高温存储性能和高温循环性能。
比较对比例4和实施例27的数据可以得到，当正极活性材料仅包括二次颗粒时，如果正极膜片层的厚度小于1.1倍正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，且恶化锂离子电池的高温存储性能和高温循环性能。
比较对比例5和实施例26的数据可以得到，正极活性材料包括一次颗粒和二次颗粒并且一次颗粒的质量占比小于20％时，如果正极膜片层的厚度小于1.1倍正极活性材料颗粒的粒径Dv99，则涂布时颗粒极易出现颗粒划痕、凸点等外观问题，且恶化锂离子电池的高温存储性能和高温循环性能。
比较实施例7至8以及实施例11至12的数据可以得到，正极集流体空白区的粗糙度和覆盖区的粗糙度过高或过低均会影响极片的外观以及锂离子电池的高温存储性能和高温循环性能。实施例11中集流体空白区的粗糙度低于500mm -1，覆盖区的粗糙度低于1500mm -1，极片外观较差，且85℃高温存储后的厚度膨胀率相对较大，45℃放电容量为80％时的循环次数减小；实施例12中集流体空白区的粗糙度高于2000mm -1，覆盖区的粗糙度高于8000mm -1，极片易出现颗粒划痕、凸点等外观问题，且85℃高温存储后的厚度膨胀率相对较大，45℃放电容量为80％时的循环次数减小。
比较实施例8和实施例13至14的数据可以得到，醚二腈添加剂影响锂离子电池的存储和高温循环性能。实施例13中未加入醚二腈添加剂，85℃高温存储后的厚度膨胀率相 对较大，45℃放电容量为80％时的循环次数减小；实施例14中加入过量的醚二腈添加剂，85℃高温存储后的厚度膨胀率相对较大，45℃放电容量为80％时的循环次数减小。
比较实施例10和实施例15的数据可以得到，电解液的电导率影响锂离子电池的高温循环性能。实施例15中电解液的电导率小于7ms/cm，45℃放电容量为80％时的循环次数减小。
比较实施例10和实施例16至17的数据可以得到，正极膜片层的厚度和正极集流体厚度影响极片外观和高温循环性能。比较实施例10、16、18和19的数据可以得到，正极膜片层的压实密度影响锂离子电池的高温存储和高温循环性能。
比较实施例28和35至36的数据可以得到，正极活性材料的粒径Dv99影响锂离子电池的高温循环性能，正极活性材料的粒径Dv99小于5μm或大于48μm，45℃放电容量为80％时的循环次数减小。

Claims (10)

  1. 一种电化学装置，包括正极，所述正极包括集流体和包括正极活性材料的膜片层，所述膜片层设置在所述集流体的至少一个表面上，所述正极活性材料包括一次颗粒和/或二次颗粒；
    当所述正极活性材料中的一次颗粒基于正极活性材料的质量百分含量A满足20％≤A≤100％时，所述膜片层、正极活性材料、集流体之间满足：D l≥Dv99-D c；
    当所述正极活性材料中的一次颗粒基于正极活性材料的质量百分含量A’满足0≤A’＜20％，所述膜片层、正极活性材料、集流体之间满足：D l≥1.1Dv99；
    其中，D l为膜片层的厚度，D c为集流体的厚度，Dv99为正极活性材料累计体积百分数达到99％时所对应的粒径。
  2. 根据权利要求1所述的电化学装置，其中，
    所述膜片层厚度D l与所述集流体厚度D c关系满足：0.05≤D l/D c≤3.75。
  3. 根据权利要求1所述的电化学装置，其中，
    所述膜片层的厚度D l为1μm至30μm。
  4. 根据权利要求1所述的电化学装置，其中，
    所述集流体的厚度D c为4μm至20μm。
  5. 根据权利要求1所述的电化学装置，其中，
    所述正极活性材料的粒径Dv99为5μm至48μm。
  6. 根据权利要求1所述的电化学装置，其中，
    所述膜片层的压实密度为2g/dm 3至4.3g/dm 3。
  7. 根据权利要求1所述的电化学装置，其中，
    所述集流体包括空白区和覆盖区；
    所述空白区为所述集流体上未覆盖膜片层的区域，所述空白区的粗糙度为500mm -1至2000mm -1；
    所述覆盖区为所述集流体上覆盖膜片层的区域，所述覆盖区的粗糙度为1500mm -1至8000mm -1。
  8. 根据权利要求1所述的电化学装置，其中，
    所述电化学装置还包括电解液，所述电解液包括醚二腈化合物；
    基于电解液的总质量，所述醚二腈化合物的质量百分含量为0.01％至15％。
  9. 根据权利要求8所述的电化学装置，其中，
    所述电解液的电导率大于等于7mS/cm。
  10. 一种电子装置，包括权利要求1-9中任一项所述的电化学装置。
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CN111916665A (zh) * 2020-09-14 2020-11-10 珠海冠宇电池股份有限公司 一种正极片及包括该正极片的锂离子电池

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