WO2023092274A1 - 电化学装置及包含该电化学装置的电子装置 - Google Patents

电化学装置及包含该电化学装置的电子装置 Download PDF

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WO2023092274A1
WO2023092274A1 PCT/CN2021/132408 CN2021132408W WO2023092274A1 WO 2023092274 A1 WO2023092274 A1 WO 2023092274A1 CN 2021132408 W CN2021132408 W CN 2021132408W WO 2023092274 A1 WO2023092274 A1 WO 2023092274A1
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Prior art keywords
active material
negative electrode
electrode active
material layer
electrochemical device
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PCT/CN2021/132408
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English (en)
French (fr)
Inventor
李晨晨
何平
刘道林
陈军
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东莞新能源科技有限公司
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Application filed by 东莞新能源科技有限公司 filed Critical 东莞新能源科技有限公司
Priority to CN202180090816.6A priority Critical patent/CN116724435A/zh
Priority to PCT/CN2021/132408 priority patent/WO2023092274A1/zh
Publication of WO2023092274A1 publication Critical patent/WO2023092274A1/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
    • 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
    • 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 including the electrochemical device.
  • fast charging technology has brought great convenience to consumers, and the key to the realization of fast charging technology lies in the use of fast charging electrode components.
  • the use of fast-charging electrode assemblies will lead to a loss of energy density of lithium-ion batteries, and if conventional measures such as increasing the compaction density of the active material layer and increasing the coating weight of the active material layer are used to improve the energy density of the lithium-ion battery Energy density will reduce the fast charging performance of lithium-ion batteries and deteriorate the expansion rate of lithium-ion batteries under fast charging conditions.
  • the purpose of the present application is to provide an electrochemical device and an electronic device including the electrochemical device, so as to increase the energy density of the electrochemical device and improve the expansion performance of the electrochemical device.
  • the first aspect of the present application provides an electrochemical device, which includes: a packaging case, a first electrode assembly and a second electrode assembly, the packaging case is provided with an accommodating cavity, and the first electrode assembly and the second electrode assembly are arranged in a housing In the cavity;
  • the first electrode assembly includes a first positive electrode sheet and a first negative electrode sheet, and the first positive electrode sheet includes a first positive electrode current collector and a first positive electrode active material layer disposed on at least one surface of the first positive electrode current collector ,
  • the first negative electrode sheet includes a first negative electrode current collector and a first negative electrode active material layer disposed on at least one surface of the first negative electrode current collector;
  • the second electrode assembly includes a second positive electrode sheet and a second negative electrode sheet, the first The two positive electrode sheets include a second positive electrode current collector and a second positive active material layer disposed on at least one surface of the second positive electrode current collector, and the second negative electrode sheet includes a second negative electrode current collector and are disposed on at least one surface of the second negative electrode current collector.
  • the value of W 2f - W 1f can be 30mg/1540.25mm 2 , 40mg/1540.25mm 2 , 50mg/1540.25mm 2 , 60mg/1540.25mm 2 , 70mg/1540.25mm 2 , 80mg/1540.25mm 2 , 90mg/1540.2mm 2 5 mm 2 , 100mg/1540.25mm 2 or any value between any two value ranges above.
  • the coating weight W 1f of the first negative electrode active material layer is less than the coating weight W 2f of the second negative electrode active material layer, and the value of W 2f -W 1f is regulated within the above range, so that the first electrode assembly is compared with the second electrode assembly.
  • the electrode assembly As far as the electrode assembly is concerned, it has better rapid charge and discharge capabilities, which can meet the needs of high power consumption applications such as games and videos. At the same time, the risk of swelling during the rapid charge and discharge process is significantly reduced.
  • the coating weight W of the second negative electrode active material layer is larger, namely it has more active materials under the same area relative to the first negative electrode active material layer, and the accumulation between active material particles can provide more Therefore, when the first electrode assembly expands during the rapid charge-discharge cycle, the second negative electrode active material layer can provide it with sufficient buffer space, thereby reducing the risk of increasing the overall volume of the electrochemical device, The expansion performance of the electrochemical device is thereby improved.
  • the coating weight W 1f of the first negative electrode active material layer is less than the coating weight W 2f of the second negative electrode active material layer, and the value of W 2f -W 1f is controlled within the above range, and the internal resistance of the first negative electrode sheet The internal resistance is smaller than the internal resistance of the second negative pole piece, so that the transmission kinetic performance of lithium ions on the first negative pole piece in the electrochemical device is improved.
  • the first electrode assembly including the first negative pole piece can quickly achieve full charging with a high charging rate.
  • the second electrode assembly including the second negative pole piece can be fully charged at a low charging rate.
  • the two electrode assemblies in the electrochemical device are arranged as a first electrode assembly of a relatively high charging rate fast charge type with a relatively low charge rate energy type second electrode assembly, ensuring the fast charging performance of the electrochemical device
  • the second negative electrode active material layer of the second electrode assembly has a relatively large coating weight, it can provide a larger capacity, thereby improving the energy density of the electrochemical device.
  • the coating weight W 1f of the first negative electrode active material layer is 50 mg/1540.25 mm 2 to 140 mg/1540.25 mm 2 ; preferably 90 mg/1540.25 mm 2 to 140 mg/1540.25 mm 2 .
  • the coating weight W 1f of the first negative electrode active material layer is 50mg/1540.25mm 2 , 60mg/1540.25mm 2 , 80mg/1540.25mm 2 , 100mg/1540.25mm 2 , 120mg/1540.25mm 2 , 140mg/1540.25mm 2 Or any value between any two value ranges above.
  • the first electrode assembly can have both higher energy density and rate performance.
  • the compacted density D 1f of the first negative electrode active material layer is 1.5 g/cm 3 to 1.8 g/cm 3 .
  • the compacted density D 1f of the first negative electrode active material layer is 1.55 g/cm 3 , 1.65 g/cm 3 , 1.78 g/cm 3 or any value between any two value ranges mentioned above.
  • the coating weight W 2f of the second negative electrode active material layer is 130 mg/1540.25 mm 2 to 170 mg/1540.25 mm 2 .
  • the coating weight W 2f of the second negative electrode active material layer is 130mg/1540.25mm 2 , 140mg/1540.25mm 2 , 150mg/1540.25mm 2 , 170mg/1540.25mm 2 or any value between any two value ranges above .
  • the second electrode assembly can be made to have a higher capacity. The volume expansion during the time provides sufficient buffer space and improves the expansion performance of the electrochemical device.
  • the compacted density D 2f of the second negative electrode active material layer is 1.5 g/cm 3 to 1.8 g/cm 3 .
  • the compacted density D 2f of the second negative electrode active material layer is 1.74 g/cm 3 , 1.75 g/cm 3 , 1.78 g/cm 3 or any value between any two value ranges mentioned above.
  • the first negative electrode active material layer includes a first negative electrode active material
  • the second negative electrode active material layer includes a second negative electrode active material, satisfying at least one of the following conditions: (a) the first The specific surface area BET 1 of the negative electrode active material is 1.6m 2 /g to 2.0m 2 /g; (b) the specific surface area BET 2 of the second negative electrode active material is 0.6m 2 /g to 1.1m 2 /g; (c) The first negative electrode active material includes at least one of graphite or lithium titanate; (d) the second negative electrode active material includes at least one of graphite or silicon-carbon composite material, and the mass percentage of silicon in the silicon-carbon composite material is W Si is 0.1% to 10%.
  • the specific surface area BET 1 of the first negative electrode active material is 1.6m 2 /g, 1.7m 2 /g, 1.8m 2 /g, 1.9m 2 /g, 2.0m 2 /g or any two of the above ranges any value of .
  • the specific surface area BET1 of the first negative electrode active material is more conducive to the improvement of the transport kinetics of lithium ions on the first negative electrode sheet, which is more conducive to reducing the first electrode assembly during the rapid charge and discharge process. , the risk of swelling of the second electrode assembly due to side reactions caused by untimely deintercalation of lithium ions.
  • the specific surface area BET 2 of the second negative electrode active material is 0.6m 2 /g, 0.7m 2 /g, 0.8m 2 /g, 0.9m 2 /g, 1.0m 2 /g, 1.1m 2 / g or the above Any value between any two value ranges.
  • the first negative electrode active material includes at least one of graphite or lithium titanate.
  • the above-mentioned material is selected as the first negative electrode active material, so that the internal resistance of the first negative electrode sheet is reduced, and the transmission kinetic performance of lithium ions on the first negative electrode sheet is improved.
  • the first electrode assembly including the first negative pole piece can quickly achieve full charging with a high charging rate.
  • the second negative electrode active material includes at least one of graphite or silicon-carbon composite material, and the mass percentage of silicon in the silicon-carbon composite material is 0.1% to 10%.
  • the mass percentage of silicon in the silicon-carbon composite material is 0.1%, 1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or Any value between any two value ranges above.
  • the above-mentioned materials are selected as the second negative electrode active material, so that the second negative electrode sheet has a good capacity, which is more conducive to improving the energy density of the electrochemical device.
  • the average particle diameter Dv50 -1 of the first negative electrode active material is 5 ⁇ m to 15 ⁇ m; the average particle diameter Dv50 -2 of the second negative electrode active material is 16 ⁇ m to 25 ⁇ m.
  • the average Dv50 -1 of the first negative electrode active material is 5 ⁇ m, 7 ⁇ m, 9 ⁇ m, 11 ⁇ m, 13 ⁇ m, 15 ⁇ m or any value between any two value ranges mentioned above.
  • the average particle diameter Dv50-2 of the second negative electrode active material is 16 ⁇ m, 18 ⁇ m, 20 ⁇ m, 22 ⁇ m, 23 ⁇ m, 25 ⁇ m or any value between any two value ranges mentioned above.
  • Dv50-1 and Dv50-2 represent the particle diameters from the small particle diameter side to 50% of volume accumulation in the volume-based particle size distribution.
  • the coating weight W 1z of the first positive electrode active material layer and the coating weight W 2z of the second positive electrode active material layer satisfy: 50mg/1540.25mm 2 ⁇ W 2z - W 1z ⁇ 190mg/1540.25mm 2 , preferably, 50mg/1540.25mm 2 ⁇ W 2z -W 1z ⁇ 150mg/1540.25mm 2 .
  • the value of W 2z -W 1z can be 50mg/1540.25mm 2 , 60mg/1540.25mm 2 , 90mg/1540.25mm 2 , 110mg/1540.25mm 2 , 130mg/1540.25mm 2 , 150mg/1540.25mm 2 , 190mg/15 40.25 mm 2 or any value between any two value ranges above.
  • the coating weight W 1z of the first positive electrode active material layer is 90mg/1540.25mm 2 to 250mg/1540.25mm 2 ; preferably 150mg/1540.25mm 2 to 250mg/1540.25mm 2 ; more Preferably it is 170 mg/1540.25 mm 2 to 250 mg/1540.25 mm 2 .
  • the coating weight W 1z of the first positive electrode active material layer is 150mg/1540.25mm 2 , 170mg/1540.25mm 2 , 180mg/1540.25mm 2 , 190mg/1540.25mm 2 , 220mg/1540.25mm 2 , 250mg/1540.25mm 2 Or any value between any two value ranges above.
  • the compacted density D 1z of the first positive electrode active material layer is 3.5 g/cm 3 to 4.5 g/cm 3 .
  • the compacted density D 1z of the first positive electrode active material layer is 4.05 g/cm 3 , 4.15 g/cm 3 , 4.23 g/cm 3 or any value between any two value ranges above.
  • the coating weight W 2z of the second positive electrode active material layer is 250 mg/1540.25 mm 2 to 315 mg/1540.25 mm 2 .
  • the coating weight W 2z of the second positive electrode active material layer is 250mg/1540.25mm 2 , 280mg/1540.25mm 2 , 310mg/1540.25mm 2 , 315mg/1540.25mm 2 or any value between any two value ranges above .
  • the compacted density D 2z of the second positive electrode active material layer is 3.5 g/cm 3 to 4.5 g/cm 3 .
  • the compacted density D 2z of the second positive electrode active material layer is 4.15 g/cm 3 , 4.18 g/cm 3 , 4.23 g/cm 3 or any value between any two value ranges above.
  • the first negative electrode piece is selected from any one of a multi-tab structure or a mid-tab structure.
  • the above-mentioned multi-tab structure means that a plurality of negative electrode tabs are connected to the first negative electrode current collector.
  • the above-mentioned “multiple tabs” refers to more than or equal to two tabs.
  • the above tab-intermediate structure means that the negative electrode tab is arranged between the two ends of the first negative electrode active material layer in the length direction.
  • the setting of the multi-tab structure or the mid-tab structure is more conducive to the multiple reduction of the conduction path of the charge on the first negative electrode sheet, so that the internal resistance of the first electrode assembly is effectively reduced, and the rate performance of the first electrode assembly is improved. , thereby improving the expansion performance of the electrochemical device.
  • the above-mentioned “tab” generally refers to the metal conductor drawn from the positive pole piece or the negative pole piece, which is used to connect in series or in parallel to other parts of the electrochemical device.
  • the positive pole lug is drawn from the positive pole piece, and the negative pole lug is drawn out from the negative pole piece.
  • the material of the tab there is no particular limitation on the material of the tab, as long as the purpose of the present application can be achieved.
  • the positive tab material includes at least one of aluminum (Al) or aluminum alloy
  • the negative tab material includes at least one of nickel (Ni), copper (Cu) or nickel-plated copper (Ni—Cu).
  • connection method between the tab and the current collector there is no special limitation on the connection method between the tab and the current collector, as long as the purpose of the present application can be achieved.
  • the direction in which the tabs are drawn out is not particularly limited, as long as the purpose of the present application can be achieved.
  • the directions in which the tabs are pulled out can be the same direction or different directions.
  • the accommodating cavity includes a first cavity and a second cavity, a separator is provided between the first cavity and the second cavity, the first electrode assembly is disposed in the first cavity, The second electrode assembly is disposed in the second cavity.
  • the first cavity and the second cavity are mutually separated cavities, wherein the first cavity contains the first electrode assembly and the electrolyte, and the second cavity contains the second electrode assembly and the electrolyte, which can reduce the The mutual interference between the first electrode assembly and the second electrode assembly during the charging and discharging process improves the charging and discharging stability of the electrochemical device.
  • the separator isolates the first electrode assembly and the second electrode assembly from each other, reducing the risk of an internal short circuit in the electrochemical device caused by contact between the positive and negative electrodes of the first electrode assembly and the second electrode assembly during external impacts such as falling.
  • the separator includes at least one of a polymer material or a metal material.
  • the above polymer materials include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol alcohol, polyamideimide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polypropylene carbonate, Poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, anhydride modified polypropylene, polyethylene, ethylene and its copolymers , polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate,
  • the aforementioned metal material includes at least one of Al, Ni, Ti, Ag, Au, Pt, Fe, Co, Cr, W, Mo, Pb, In, Zn or stainless steel.
  • the present application has no particular limitation on the thickness of the separator, as long as the purpose of the present application can be achieved.
  • the thickness of the separator is 2 ⁇ m to 100 ⁇ m, preferably 5 ⁇ m to 50 ⁇ m, more preferably 5 ⁇ m to 20 ⁇ m.
  • the first positive electrode sheet of the present application includes a first positive electrode current collector and a first positive electrode active material layer disposed on at least one surface of the first positive electrode current collector. This application has no special restrictions on the first positive electrode current collector, as long as the present The purpose of application is sufficient.
  • the second positive electrode sheet of the present application includes a second positive electrode current collector and a second positive electrode active material layer disposed on at least one surface of the second positive electrode current collector. The present application has no special restrictions on the second positive electrode current collector, as long as the present The purpose of application is sufficient.
  • the first positive electrode current collector/the second positive electrode current collector may include aluminum foil, aluminum alloy foil, composite current collector, or the like.
  • the application does not have special restrictions on the type of the first positive electrode active material/second positive electrode active material, as long as the purpose of the application can be achieved.
  • the first positive electrode active material/second positive electrode active material includes nickel cobalt lithium manganate (811, 622, 523, 111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium cobalt oxide, lithium manganate or lithium manganese iron phosphate.
  • the thicknesses of the first positive electrode current collector/second positive electrode current collector and the first positive electrode active material layer/second positive electrode active material layer as long as the purpose of the present application can be achieved.
  • the thickness of the first positive current collector/second positive current collector is 5 ⁇ m to 20 ⁇ m, preferably 6 ⁇ m to 18 ⁇ m.
  • the thickness of the single-side first positive electrode active material layer/single-side second positive electrode active material layer is 30 ⁇ m to 120 ⁇ m.
  • the first positive electrode active material layer/second positive electrode active material layer can be arranged on one surface in the thickness direction of the first positive electrode current collector/second positive electrode current collector, or can be arranged on the first positive electrode current collector/ On both surfaces in the thickness direction of the second positive current collector. It should be noted that the "surface” here may be the entire area of the first positive current collector/second positive current collector, or a partial area of the first positive current collector/second positive current collector.
  • the first positive electrode sheet/the second positive electrode sheet can also include a conductive layer, and the conductive layer is located between the first positive electrode current collector and the first positive electrode active material layer/the second positive electrode current collector and the second positive electrode active material between layers.
  • the composition of the conductive layer is not particularly limited, and may be a commonly used conductive layer in the field.
  • the conductive layer includes a conductive agent and a binder.
  • the first negative electrode sheet of the present application includes a first negative electrode current collector and a first negative electrode active material layer disposed on at least one surface of the first negative electrode current collector.
  • the present application has no particular limitation on the first negative electrode collector, as long as the purpose of the present application can be achieved.
  • the second negative electrode sheet of the present application includes a second negative electrode current collector and a second negative electrode active material layer disposed on at least one surface of the second negative electrode current collector.
  • the present application has no special limitation on the second negative electrode collector, as long as the purpose of the present application can be achieved.
  • the first negative electrode current collector/second negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a composite current collector.
  • the thicknesses of the first negative electrode current collector/second negative electrode current collector and the first negative electrode active material layer/second negative electrode active material layer there is no particular limitation on the thicknesses of the first negative electrode current collector/second negative electrode current collector and the first negative electrode active material layer/second negative electrode active material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the first negative electrode current collector/the second negative electrode current collector is 6 ⁇ m to 10 ⁇ m
  • the thickness of the single-side first negative electrode active material layer/single-side second negative electrode active material layer is 30 ⁇ m to 130 ⁇ m.
  • the first negative electrode active material layer/second negative electrode active material layer can be arranged on one surface in the thickness direction of the first negative electrode current collector/second negative electrode current collector, or can be arranged on the first negative electrode current collector/ On both surfaces in the thickness direction of the second negative electrode current collector.
  • the "surface” here can be the entire area of the first negative electrode current collector/second negative electrode current collector, or a partial area of the first negative electrode current collector/second negative electrode current collector. This application is not particularly limited, as long as It is enough to realize the purpose of this application.
  • the first negative electrode sheet/the second negative electrode sheet can also include a conductive layer, and the conductive layer is located between the first negative electrode current collector and the first negative electrode active material layer/the second negative electrode current collector and the second negative electrode active material between layers.
  • the composition of the conductive layer is not particularly limited, and may be a commonly used conductive layer in the field.
  • the conductive layer includes a conductive agent and a binder.
  • the conductive agent mentioned above is not particularly limited, as long as the purpose of the present application can be achieved.
  • the conductive agent may include at least one of conductive carbon black, carbon nanotubes, carbon nanofibers, graphite, acetylene black, Ketjen black, carbon dots, or graphene.
  • the binder may include polyacryl alcohol, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyimide, polyamideimide, styrene-butadiene rubber (SBR), polyvinyl alcohol ( PVA), polyvinylidene fluoride, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin, carboxymethyl cellulose (CMC) or carboxymethyl At least one of sodium cellulose base (CMC-Na).
  • SBR styrene-butadiene rubber
  • PVA polyvinyl alcohol
  • PVDF polyvinylidene fluoride
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVB polyvinyl butyral
  • water-based acrylic resin carboxymethyl cellulose (CMC) or carboxymethyl At least one of sodium cellulose base (CMC-Na).
  • the first electrode assembly of the present application further includes a separator located between the first positive electrode sheet and the first negative electrode sheet.
  • the second electrode assembly of the present application further includes a separator located between the second positive electrode sheet and the second negative electrode sheet.
  • the separator is used to separate the first positive pole piece and the first negative pole piece, as well as the second positive pole piece and the second negative pole piece, so as to prevent the internal short circuit of the lithium-ion battery, allow the electrolyte ions to pass freely, and complete the electrochemical charging and discharging process. effect.
  • the present application has no particular limitation on the separator, as long as the purpose of the present application can be achieved.
  • a separator may include a substrate layer and a surface treatment layer.
  • the substrate layer can be a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer can include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide, etc. kind.
  • the material of the substrate layer can include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide, etc. kind.
  • at least one of a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film, etc. may be used.
  • the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material.
  • the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, for example, they can be selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, 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.
  • the binder is not particularly limited, for example, it can be selected from polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinyl pyrene At least one of rolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer comprises a polymer, and the polymer material includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( at least one of vinylidene fluoride-hexafluoropropylene) and the like.
  • the electrochemical device of the present application also includes an electrolytic solution, and the electrolytic solution includes a lithium salt and a non-aqueous solvent.
  • the lithium salt there is no particular limitation on the lithium salt, as long as the purpose of this application can be achieved.
  • lithium salts may include LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 At least one of CF 3 ) 3 , LiSiF 6 , LiBOB or lithium difluoroborate.
  • the nonaqueous solvent may be at least one of carbonate compounds, carboxylate compounds, ether compounds, or other organic solvents.
  • the above-mentioned carbonate compound may be at least one of chain carbonate compound, cyclic carbonate compound or fluorocarbonate compound.
  • Examples of the above-mentioned chain carbonate compound are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylenepropyl carbonate (EPC) or carbonic acid At least one of methyl ethyl ester (MEC).
  • cyclic carbonate compound is at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or vinylethylene carbonate (VEC).
  • fluorocarbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethyl carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-dicarbonate At least one of fluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate.
  • Examples of the above carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , at least one of decanolactone, valerolactone, mevalonolactone or caprolactone.
  • Examples of the aforementioned ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl At least one of oxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • Examples of the aforementioned other organic solvents are dimethylsulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, At least one of formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphoric acid ester.
  • the present application has no special restrictions on the structures of the first electrode assembly and the second electrode assembly, as long as the purpose of the application can be achieved.
  • the structure of the first electrode assembly may include a wound structure or a laminated structure.
  • the structure of the second electrode assembly may be a wound structure or a laminated structure.
  • the structures of the first electrode assembly and the second electrode assembly may be the same or different.
  • the first electrode assembly is a wound structure
  • the second electrode assembly is a wound structure.
  • the first electrode assembly is a lamination structure
  • the second electrode assembly is a lamination structure.
  • the first electrode assembly is a lamination structure, and the second electrode assembly is a winding structure. In some other embodiments of the present application, the first electrode assembly is a wound structure, and the second electrode assembly is a laminated structure.
  • the packaging case may include at least one of an aluminum-plastic film, an aluminum case, a steel case or a plastic case.
  • the packaging shell may have a thickness of 60 ⁇ m to 500 ⁇ m, preferably 60 ⁇ m to 300 ⁇ m, more preferably 60 ⁇ m to 200 ⁇ m.
  • the packaging shell with the above thickness can effectively protect the internal structure of the electrochemical device.
  • 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, and the like.
  • the preparation process of the electrochemical device 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: stacking the first positive electrode sheet, the separator and the first negative electrode sheet in sequence, And according to the needs of winding, folding and other operations to obtain the first electrode assembly of the winding structure, put the first electrode assembly into the packaging case; stack the second positive electrode sheet, separator and second negative electrode sheet in order, And according to the needs of winding, folding and other operations to obtain the second electrode assembly of the winding structure, the second electrode assembly is placed in the packaging case; the first electrode assembly and the second electrode assembly are separated by a separator; the electrolytic The liquid is injected into the packaging case and sealed to obtain an electrochemical device; or, stack the first positive electrode sheet, the separator and the first negative electrode sheet in sequence, and then use adhesive tape to fix the four corners of the entire laminated structure to obtain a laminated structure
  • the first electrode assembly of the first electrode assembly, the electrode assembly is placed in the packaging case; the second positive electrode sheet, the separator and the second negative electrode sheet are stacked in order, and then the four corners of the entire laminated
  • the second aspect of the present application provides an electronic device comprising the electrochemical device described in any one of the foregoing embodiments of the present application. Therefore, the electronic device has high energy density and good expansion performance.
  • the present application provides an electrochemical device and an electronic device containing the electrochemical device.
  • the electrochemical device includes a packaging case, a first electrode assembly and a second electrode assembly.
  • the packaging case is provided with an accommodating cavity, the first electrode assembly and the second electrode assembly.
  • the second electrode assembly is disposed in the housing cavity;
  • the first electrode assembly includes a first positive pole piece and a first negative pole piece, and the first positive pole piece includes a first positive current collector and is arranged on at least one surface of the first positive current collector
  • the first positive electrode active material layer, the first negative electrode sheet includes a first negative electrode current collector and the first negative electrode active material layer disposed on at least one surface of the first negative electrode current collector;
  • the second electrode assembly includes a second positive electrode sheet and The second negative pole piece,
  • the second positive pole piece comprises a second positive current collector and a second positive active material layer arranged on at least one surface of the second positive current collector,
  • the second negative pole piece comprises a second negative current collector and The second negative electrode active material layer on at
  • FIG. 1 is a schematic diagram of the internal structure of an electrochemical device according to an embodiment of the present application.
  • Fig. 2 is a schematic structural diagram of area A in Fig. 1;
  • Fig. 3 is a schematic structural diagram of the first positive pole piece according to an embodiment of the present application.
  • Fig. 4 is a schematic structural diagram of the first negative pole piece in the scheme of Fig. 3 .
  • Fig. 1 shows a schematic diagram of the internal structure of an electrochemical device according to an embodiment of the present application.
  • the electrochemical device 100 includes: a packaging case 10, a first electrode assembly 21 and a second electrode assembly 22, and the packaging case 10 is provided with an accommodating cavity, the accommodating cavity includes a first cavity 31 and a second cavity 32, a separator 40 is provided between the first cavity 31 and the second cavity 32, and the first electrode assembly 21 is arranged on the first The cavity 31 , the second electrode assembly 22 is disposed in the second cavity 32 .
  • Fig. 2 is a schematic structural view of area A in Fig. 1.
  • the structure of the first electrode assembly 21 is a multi-tab structure, specifically, through the first positive pole piece 211, the diaphragm 230, the first negative pole piece 212 and the separator 230 are wound into a multi-tab structure core, the first positive electrode piece 211 includes a plurality of positive electrode tabs (not shown), and the first negative electrode piece 212 includes a plurality of negative electrode tabs 52 .
  • Figure 3 shows a schematic structural view of the first positive electrode sheet of some embodiments of the present application, as shown in Figure 3, the first positive electrode tab 51 is arranged at both ends of the length direction of the positive electrode active material layer in the first positive electrode sheet 211 between.
  • Figure 4 shows a schematic structural view of the first negative electrode sheet of some embodiments of the present application, as shown in Figure 4, the first negative electrode tab 52 is arranged at both ends of the length direction of the negative electrode active material layer in the first negative electrode sheet 212 between.
  • the structure of the first positive pole piece 211 shown in FIG. 3 and the first negative pole piece 212 shown in FIG. 4 is a tab-centered structure.
  • 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 coating weight m1-m2.
  • coating weight (m1-m2)/2.
  • compaction density 10 ⁇ (M1-M2)/(S1 ⁇ (H2-H1)).
  • the average particle diameter Dv50 -1 of the first negative electrode active material and the average particle diameter Dv50 -2 of the second negative electrode active material were tested by using a laser particle size analyzer.
  • the capacity ratio of the first electrode assembly C1/(C1+C2) ⁇ 100%.
  • first negative electrode active material Mix graphite, styrene-butadiene rubber, and sodium carboxymethylcellulose as the first negative electrode active material according to a mass ratio of 97:2:1, add deionized water, prepare a slurry with a solid content of 70%, and stir evenly. Apply the slurry evenly on one surface of the first negative electrode current collector copper foil, and dry it at 110°C, and then repeat the above steps on the other surface of the first negative electrode current collector copper foil to obtain a double-sided A first negative electrode sheet coated with a first negative electrode active material layer. After the coating is completed, the first negative pole piece is cold-pressed, cut into a size of 76 mm ⁇ 851 mm and welded to tabs for use.
  • the coating weight W 1f of the first negative electrode active material layer is 120mg/1540.25mm 2
  • the compacted density D 1f of the first negative electrode active material layer is 1.55g/cm 3
  • the specific surface area BET of the first negative electrode active material is 1 was 1.9 m 2 /g
  • the average particle diameter Dv50 -1 of the first negative electrode active material was 10 ⁇ m.
  • the first positive electrode active material lithium cobaltate (LiCoO 2 ), the conductive agent conductive carbon black, and the binder polyvinylidene fluoride (PVDF) were mixed according to the mass ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP ), prepared into a slurry with a solid content of 75%, and stirred evenly. Apply the slurry evenly on one surface of the first positive electrode current collector aluminum foil, and dry it at 130°C, and then repeat the above steps on the other surface of the first positive electrode current collector aluminum foil to obtain double-sided coating
  • the positive electrode sheet of the first positive electrode active material layer The positive electrode sheet of the first positive electrode active material layer.
  • the first positive pole piece is cold-pressed, cut into a size of 74mm ⁇ 867mm, and welded to tabs for use.
  • the coating weight W 1z of the first positive electrode active material layer is 220 mg/1540.25 mm 2
  • the compacted density D 1z of the first positive electrode active material layer is 4.05 g/cm 3 .
  • the coating weight W 2f of the second negative electrode active material layer is 150 mg/1540.25 mm 2
  • the compacted density D 2f of the second negative electrode active material layer is 1.75 g/cm 3
  • the specific surface area BET 2 of the second negative electrode active material is The average particle diameter Dv50 -2 of the second negative electrode active material was 20 ⁇ m.
  • the second positive electrode active material lithium cobaltate (LiCoO 2 ), the conductive agent conductive carbon black, and the binder polyvinylidene fluoride (PVDF) were mixed according to the mass ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP ), prepared into a slurry with a solid content of 75%, and stirred evenly. Apply the slurry evenly on one surface of the second positive electrode current collector aluminum foil, and dry it at 130°C, and then repeat the above steps on the other surface of the second positive electrode current collector aluminum foil to obtain double-sided coating
  • the positive electrode sheet of the second positive electrode active material layer LiCoO 2
  • the conductive agent conductive carbon black the binder polyvinylidene fluoride (PVDF)
  • the second positive pole piece is cold-pressed, cut into a size of 74mm ⁇ 867mm, and welded to tabs for use.
  • the coating weight W 2z of the second positive electrode active material layer is 280 mg/1540.25 mm 2
  • the compacted density D 2z of the second positive electrode active material layer is 4.18 g/cm 3 .
  • a polypropylene (PP) film with a thickness of 14 ⁇ m was used.
  • the structure of the first electrode assembly is a tab-centered structure.
  • the coating weight W 1f of the first negative electrode active material layer In addition to adjusting the coating weight W 1f of the first negative electrode active material layer, the coating weight W 1z of the first positive electrode active material layer, the coating weight W 2f of the second negative electrode active material layer, and the weight of the second negative electrode active material according to Table 3. Except for the type, the specific surface area BET 2 of the second negative electrode active material, and the coating weight W 2z of the second positive electrode active material layer, the rest are the same as in Examples 1-3.
  • Comparative Example 1 to Comparative Example 2 From Example 1-1 to Example 1-7, Comparative Example 1 to Comparative Example 2, it can be seen that the expansion performance and energy density of the lithium ion battery increase with the coating weight W 1f of the first negative electrode active material layer and the second The difference W 2f ⁇ W 1f of the coating weight W 2f of the negative electrode active material layer varies.
  • the lithium-ion battery with W 2f -W 1f within the scope of this application has better expansion performance and energy density than Comparative Example 1 where W 2f - W 1f ⁇ 30.
  • the second negative electrode active material layer The coating weight W of 2f is larger, that is, it has more active materials under the same area relative to the first negative electrode active material layer, and the accumulation of active material particles can provide more pores, therefore, the first electrode assembly is at high
  • the second negative electrode active material layer can provide sufficient buffer space for it, thereby reducing the overall volume growth rate of the electrochemical device, thereby improving the expansion performance of the electrochemical device.
  • Example 2-1 to Example 2-6 From Example 1-3, Example 2-1 to Example 2-6, it can be seen that the specific surface area BET 1 of the first negative electrode active material is in the range of 1.6m 2 /g to 2.0m 2 /g in Example 1-3 , Example 2-1 to Example 2-2 have more excellent expansion properties compared to Example 2-3, this is because: the specific surface area of the first negative electrode active material is within the above-mentioned range, on the one hand, can satisfy Under the condition of high-rate charge and discharge, the lithium ion deintercalation rate is required, thereby reducing side reactions such as lithium precipitation; Increased side reactions, thus improving swelling properties.
  • Example 2-6 Compared with Example 2-6, the specific surface area BET of the second negative electrode active material is 0.6m 2 /g to 1.1m 2 /g in Example 1-3, Example 2-4 to Example 2-5, which has Higher energy density, and, due to the smaller contact area with the electrolyte during charging and discharging, fewer side reactions occur, so it can have better expansion performance.
  • Example 3-1 to Example 3-3 From Example 1-3, Example 3-1 to Example 3-3, it can be seen that the type of the second negative electrode active material is Silicon Carbon Composite Material Example 3-1 to Example 3-3, at W 2f When -W 1f is within the scope of the present application, it also has better expansion performance, and at the same time, the energy density is higher.

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Abstract

本申请提供了一种电化学装置及包含该电化学装置的电子装置，该电化学装置中第一负极活性材料层的涂布重量W 1f与第二负极活性材料层的涂布重量W 2f之间满足：30mg/1540.25mm 2≤W 2f－W 1f≤100mg/1540.25mm 2。通过将W 2f－W 1f的值调控在上述范围内，在满足快充性能的同时，能够提高电化学装置的能量密度、并改善电化学装置的膨胀性能。

Description

电化学装置及包含该电化学装置的电子装置 技术领域
本申请涉及电化学领域，具体涉及一种电化学装置及包含该电化学装置的电子装置。
背景技术
近年来，快充技术给消费者带来了巨大的便利，而快充技术的实现关键在于快充型电极组件的使用。然而，快充型电极组件的使用会带来锂离子电池能量密度的损失，并且如果采用常规的提高活性材料层的压实密度、增加活性材料层的涂布重量等措施来提高锂离子电池的能量密度，则会降低锂离子电池的快充性能，并恶化锂离子电池在快充条件下的膨胀率。
发明内容
本申请的目的在于提供一种电化学装置及包含该电化学装置的电子装置，以提高电化学装置的能量密度，并改善电化学装置的膨胀性能。
本申请的第一方面提供了一种电化学装置，其包括：包装壳、第一电极组件和第二电极组件，包装壳设置有容纳腔体，第一电极组件和第二电极组件设置于容纳腔体内；第一电极组件包括第一正极极片和第一负极极片，第一正极极片包括第一正极集流体和设置于第一正极集流体至少一个表面上的第一正极活性材料层，第一负极极片包括第一负极集流体和设置于第一负极集流体至少一个表面上的第一负极活性材料层；第二电极组件包括第二正极极片和第二负极极片，第二正极极片包括第二正极集流体和设置于第二正极集流体至少一个表面上的第二正极活性材料层，第二负极极片包括第二负极集流体和设置于第二负极集流体至少一个表面上的第二负极活性材料层；第一负极活性材料层的涂布重量W 1f与第二负极活性材料层的涂布重量W 2f之间满足：30mg/1540.25mm 2≤W 2f－W 1f≤100mg/1540.25mm 2。
例如，W 2f－W 1f的值可以为30mg/1540.25mm 2、40mg/1540.25mm 2、50mg/1540.25mm 2、60mg/1540.25mm 2、70mg/1540.25mm 2、80mg/1540.25mm 2、90mg/1540.25mm 2、100mg/1540.25mm 2或上述任两个数值范围间的任一数值。
第一负极活性材料层的涂布重量W 1f小于第二负极活性材料层的涂布重量W 2f，且W 2f－W 1f的值调控在上述范围内，使第一电极组件相比于第二电极组件而言，具有更优异的 快速充放电能力，能够满足游戏、视频等高功耗应用的需求，同时，其在快速充放电过程中发生膨胀的风险显著降低。并且，第二负极活性材料层的涂布重量W 2f较大，即其相对于第一负极活性材料层在相同面积下具有更多的活性材料，活性材料颗粒之间的堆积能够提供更多的孔隙，因此，第一电极组件在快速充放电循环过程中发生膨胀时，第二负极活性材料层能够为其提供充足的缓冲空间，由此，减小了电化学装置整体体积增大的风险，从而改善了电化学装置的膨胀性能。
此外，第一负极活性材料层的涂布重量W 1f小于第二负极活性材料层的涂布重量W 2f，且W 2f－W 1f的值调控在上述范围内，第一负极极片的内阻小于第二负极极片的内阻，使电化学装置中锂离子在第一负极极片上的传输动力学性能得以提高。包含第一负极极片的第一电极组件能够以高充电倍率快速实现满充。包含第二负极极片的第二电极组件能够以低充电倍率实现满充。这样，将电化学装置中的两个电极组件设置成一个相对高充电倍率快充型的第一电极组件搭配一个相对低充电倍率能量型的第二电极组件，在保证电化学装置的快充性能的同时，由于第二电极组件的第二负极活性材料层具有相对较大的涂布重量，能够提供更大的容量，由此，使电化学装置的能量密度得以提升。
在本申请的一种实施方案中，第一负极活性材料层的涂布重量W 1f为50mg/1540.25mm 2至140mg/1540.25mm 2；优选为90mg/1540.25mm 2至140mg/1540.25mm 2。例如，第一负极活性材料层的涂布重量W 1f为50mg/1540.25mm 2、60mg/1540.25mm 2、80mg/1540.25mm 2、100mg/1540.25mm 2、120mg/1540.25mm 2、140mg/1540.25mm 2或上述任两个数值范围间的任一数值。通过将第一负极活性材料层的涂布重量W 1f调控在上述范围内，能够使第一电极组件兼具较高的能量密度和倍率性能。
在本申请的一种实施方案中，第一负极活性材料层的压实密度D 1f为1.5g/cm 3至1.8g/cm 3。例如，第一负极活性材料层的压实密度D 1f为1.55g/cm 3、1.65g/cm 3、1.78g/cm 3或上述任两个数值范围间的任一数值。通过将第一负极活性材料层的压实密度D 1f调控在上述范围内，能够在提高第一电极组件能量密度的同时，保证第一负极活性材料层具有合适的孔隙，进而改善电化学装置的膨胀性能。
在本申请的一种实施方案中，第二负极活性材料层的涂布重量W 2f为130mg/1540.25mm 2至170mg/1540.25mm 2。例如，第二负极活性材料层的涂布重量W 2f为130mg/1540.25mm 2、140mg/1540.25mm 2、150mg/1540.25mm 2、170mg/1540.25mm 2或上述任两个数值范围间的任一数值。通过将第二负极活性材料层的涂布重量W 2f调控在上述范 围内，能够使第二电极组件具有较高的容量，同时，第二负极活性材料层能够为第一电极组件在快速充放电时的体积膨胀提供充分的缓冲空间，改善电化学装置的膨胀性能。
在本申请的一种实施方案中，第二负极活性材料层的压实密度D 2f为1.5g/cm 3至1.8g/cm 3。例如，第二负极活性材料层的压实密度D 2f为1.74g/cm 3、1.75g/cm 3、1.78g/cm 3或上述任两个数值范围间的任一数值。通过将第二负极活性材料层的压实密度D 2f调控在上述范围内，能够在提高第二电极组件能量密度的同时，保证其有充足的孔隙，进而改善电化学装置的膨胀性能。
在本申请的一种实施方案中，第一负极活性材料层包括第一负极活性材料，第二负极活性材料层包括第二负极活性材料，满足以下条件中的至少一者：(a)第一负极活性材料的比表面积BET 1为1.6m 2/g至2.0m 2/g；(b)第二负极活性材料的比表面积BET 2为0.6m 2/g至1.1m 2/g；(c)第一负极活性材料包括石墨或钛酸锂中的至少一种；(d)第二负极活性材料包括石墨或硅碳复合材料中的至少一种，硅碳复合材料中硅的质量百分含量W Si为0.1％至10％。
例如，第一负极活性材料的比表面积BET 1为1.6m 2/g、1.7m 2/g、1.8m 2/g、1.9m 2/g、2.0m 2/g或上述任两个数值范围间的任一数值。通过将第一负极活性材料的比表面积BET 1调控在上述范围内，更利于锂离子在第一负极极片上的传输动力学性能的提高，从而更利于降低第一电极组件在快速充放电过程中，由于锂离子脱嵌不及时引发的副反应导致第二电极组件发生膨胀的风险。
例如，第二负极活性材料的比表面积BET 2为0.6m 2/g、0.7m 2/g、0.8m 2/g、0.9m 2/g、1.0m 2/g、1.1m 2/g或上述任两个数值范围间的任一数值。通过将第二负极活性材料的比表面积BET 2调控在上述范围内，更利于第二负极极片容量的提高，从而更利于改善电化学装置的能量密度。
其中，第一负极活性材料包括石墨或钛酸锂中的至少一种。选用上述材料用作第一负极活性材料，使第一负极极片的内阻减小，锂离子在第一负极极片上的传输动力学性能得以提高。包含第一负极极片的第一电极组件能够以高充电倍率快速实现满充。
第二负极活性材料包括石墨或硅碳复合材料中的至少一种，硅碳复合材料中硅的质量百分含量为0.1％至10％。例如，硅碳复合材料中硅的质量百分含量为0.1％、1％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或上述任两个数值范围间的任一数值。选用上述 材料用作第二负极活性材料，使第二负极极片具有良好的容量，更利于改善电化学装置的能量密度。
在本申请的一种实施方案中，第一负极活性材料的平均粒径Dv50 -1为5μm至15μm；第二负极活性材料的平均粒径Dv50 -2为16μm至25μm。例如，第一负极活性材料的平均Dv50 -1为5μm、7μm、9μm、11μm、13μm、15μm或上述任两个数值范围间的任一数值。第二负极活性材料的平均粒径Dv50 -2为16μm、18μm、20μm、22μm、23μm、25μm或上述任两个数值范围间的任一数值。本申请中Dv50 -1和Dv50 -2表示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。
在本申请的一种实施方案中，第一正极活性材料层的涂布重量W 1z与第二正极活性材料层的涂布重量W 2z之间满足：50mg/1540.25mm 2≤W 2z－W 1z≤190mg/1540.25mm 2，优选地，50mg/1540.25mm 2≤W 2z－W 1z≤150mg/1540.25mm 2。例如，W 2z－W 1z的值可以为50mg/1540.25mm 2、60mg/1540.25mm 2、90mg/1540.25mm 2、110mg/1540.25mm 2、130mg/1540.25mm 2、150mg/1540.25mm 2、190mg/1540.25mm 2或上述任两个数值范围间的任一数值。
在本申请的一种实施方案中，第一正极活性材料层的涂布重量W 1z为90mg/1540.25mm 2至250mg/1540.25mm 2；优选为150mg/1540.25mm 2至250mg/1540.25mm 2；更优选为170mg/1540.25mm 2至250mg/1540.25mm 2。例如，第一正极活性材料层的涂布重量W 1z为150mg/1540.25mm 2、170mg/1540.25mm 2、180mg/1540.25mm 2、190mg/1540.25mm 2、220mg/1540.25mm 2、250mg/1540.25mm 2或上述任两个数值范围间的任一数值。
在本申请的一种实施方案中，第一正极活性材料层的压实密度D 1z为3.5g/cm 3至4.5g/cm 3。例如，第一正极活性材料层的压实密度D 1z为4.05g/cm 3、4.15g/cm 3、4.23g/cm 3或上述任两个数值范围间的任一数值。
在本申请的一种实施方案中，第二正极活性材料层的涂布重量W 2z为250mg/1540.25mm 2至315mg/1540.25mm 2。例如，第二正极活性材料层的涂布重量W 2z为250mg/1540.25mm 2、280mg/1540.25mm 2、310mg/1540.25mm 2、315mg/1540.25mm 2或上述任两个数值范围间的任一数值。
在本申请的一种实施方案中，第二正极活性材料层的压实密度D 2z为3.5g/cm 3至4.5g/cm 3。例如，第二正极活性材料层的压实密度D 2z为4.15g/cm 3、4.18g/cm 3、4.23g/cm 3 或上述任两个数值范围间的任一数值。
在本申请的一种实施方案中，第一负极极片选自多极耳结构或极耳中置结构中的任一种。
其中，上述多极耳结构是指，第一负极集流体上连接多个负极极耳。上述“多极耳”是指大于或等于两个极耳。上述极耳中置结构是指，将负极极耳设置于第一负极活性材料层长度方向的两端之间。多极耳结构或极耳中置结构的设置更有利于电荷在第一负极极片上的传导路径成倍缩短，从而使第一电极组件的内阻有效降低，使第一电极组件的倍率性能提高，进而改善电化学装置的膨胀性能。
在本申请中，上述的“极耳”通常是指，从正极极片或负极极片上引出来的金属导体，用于串联连接或并联连接电化学装置的其它部分。正极极耳从正极极片上引出，负极极耳从负极极片上引出。在本申请中，对极耳的材料不做特别限定，只要能实现本申请的目的即可。例如，正极极耳材料包括铝(Al)或铝合金中的至少一种，负极极耳材料包括镍(Ni)、铜(Cu)或铜镀镍(Ni-Cu)中的至少一种。在本申请中，对极耳与集流体的连接方式不做特别限定，只要能实现本申请的目的即可。例如，激光焊、超声焊、电阻焊或一体成型等中的至少一种。在本申请中，所述极耳引出的方向没有特别限定，只要能实现本申请的目的即可。例如，极耳引出的方向可以为同向或异向。
在本申请的一种实施方案中，容纳腔体包括第一腔体和第二腔体，第一腔体和第二腔体之间具有隔板，第一电极组件设置于第一腔体，第二电极组件设置于第二腔体。这样，第一腔体与第二腔体为相互隔开的腔体，其中，第一腔体包含第一电极组件和电解液，第二腔体包含第二电极组件和电解液，能够降低第一电极组件和第二电极组件在充放电过程中的相互干扰，提高电化学装置的充放电的稳定性。同时，隔板使第一电极组件和第二电极组件之间相互隔绝，降低第一电极组件与第二电极组件在跌落等外部冲击过程中正负极接触引发电化学装置内部短路的风险。
本申请对隔板的种类没有特别限制，只要能够实现本申请目的即可。例如，隔板包括高分子材料或金属材料中的至少一种。上述高分子材料包括聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚萘二甲酸乙二醇酯、聚醚醚酮、聚酰亚胺、聚酰胺、聚乙二醇、聚酰胺酰亚胺、聚碳酸酯、环状聚烯烃、聚苯硫醚、聚乙酸乙烯酯、聚四氟乙烯，聚亚甲基萘、聚偏二氟乙烯、聚碳酸亚丙酯、聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-共-三氟氯 乙烯)、有机硅、维尼纶、聚丙烯、酸酐改性聚丙烯、聚乙烯、乙烯及其共聚物、聚氯乙烯、聚苯乙烯、聚醚腈、聚氨酯、聚苯醚、聚酯、聚砜、非晶态α-烯烃共聚物或上述物质衍生物中的至少一种。上述金属材料包括Al、Ni、Ti、Ag、Au、Pt、Fe、Co、Cr、W、Mo、Pb、In、Zn或不锈钢中的至少一种。本申请对隔板的厚度没有特别限制，只要能够实现本申请目的即可。例如，隔板的厚度为2μm至100μm，优选为5μm至50μm，更优选为5μm至20μm。
本申请的第一正极极片包括第一正极集流体和设置于第一正极集流体至少一个表面上的第一正极活性材料层，本申请对第一正极集流体没有特别限制，只要能够实现本申请目的即可。本申请的第二正极极片包括第二正极集流体和设置于第二正极集流体至少一个表面上的第二正极活性材料层，本申请对第二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，第一正极集流体/第二正极集流体可以包含铝箔、铝合金箔或复合集流体等。本申请对第一正极活性材料/第二正极活性材料的种类没有特别限制，只要能够实现本申请目的即可例如，第一正极活性材料/第二正极活性材料包括镍钴锰酸锂(811、622、523、111)、镍钴铝酸锂、磷酸铁锂、钴酸锂、锰酸锂或磷酸锰铁锂中的至少一种。在本申请中，对第一正极集流体/第二正极集流体和第一正极活性材料层/第二正极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，第一正极集流体/第二正极集流体的厚度为5μm至20μm，优选为6μm至18μm。单面第一正极活性材料层/单面第二正极活性材料层的厚度为30μm至120μm。在本申请中，第一正极活性材料层/第二正极活性材料层可以设置于第一正极集流体/第二正极集流体厚度方向上的一个表面上，也可以设置于第一正极集流体/第二正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是第一正极集流体/第二正极集流体的全部区域，也可以是第一正极集流体/第二正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。任选地，第一正极极片/第二正极极片还可以包含导电层，导电层位于第一正极集流体和第一正极活性材料层之间/第二正极集流体和第二正极活性材料层之间。导电层的组成没有特别限制，可以是本领域常用的导电层。导电层包括导电剂和粘结剂。
本申请的第一负极极片包括第一负极集流体和设置于第一负极集流体至少一个表面上的第一负极活性材料层。本申请对第一负极集流体没有特别限制，只要能够实现本申请目的即可。本申请的第二负极极片包括第二负极集流体和设置于第二负极集流体至少一个表面上的第二负极活性材料层。本申请对第二负极集流体没有特别限制，只要能够实现本申请目的即可。例如，第一负极集流体/第二负极集流体可以包含铜箔、铜合金箔、镍箔、 不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。在本申请中，对第一负极集流体/第二负极集流体和第一负极活性材料层/第二负极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，第一负极集流体/第二负极集流体的厚度为6μm至10μm，单面第一负极活性材料层/单面第二负极活性材料层的厚度为30μm至130μm。在本申请中，第一负极活性材料层/第二负极活性材料层可以设置于第一负极集流体/第二负极集流体厚度方向上的一个表面上，也可以设置于第一负极集流体/第二负极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是第一负极集流体/第二负极集流体的全部区域，也可以是第一负极集流体/第二负极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。任选地，第一负极极片/第二负极极片还可以包含导电层，导电层位于第一负极集流体和第一负极活性材料层之间/第二负极集流体和第二负极活性材料层之间。导电层的组成没有特别限制，可以是本领域常用的导电层。导电层包括导电剂和粘结剂。
上述导电剂没有特别限制，只要能够实现本申请目的即可。例如，导电剂可以包括导电炭黑、碳纳米管、碳纳米纤维、石墨、乙炔黑、科琴黑、碳点或石墨烯中的至少一种。例如，粘结剂可以包括聚丙烯醇、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酸锂、聚酰亚胺、聚酰亚胺、聚酰胺酰亚胺、丁苯橡胶(SBR)、聚乙烯醇(PVA)、聚偏氟乙烯、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、水性丙烯酸树脂、羧甲基纤维素(CMC)或羧甲基纤维素钠(CMC-Na)中的至少一种。
本申请的第一电极组件还包括隔膜，隔膜位于第一正极极片和第一负极极片之间。本申请的第二电极组件还包括隔膜，隔膜位于第二正极极片和第二负极极片之间。隔膜用以分隔第一正极极片和第一负极极片，以及第二正极极片和第二负极极片，从而防止锂离子电池内部短路，允许电解质离子自由通过，完成电化学充放电过程的作用。
本申请对隔膜没有特别限制，只要能够实现本申请目的即可。例如，聚乙烯(PE)、聚丙烯(PP)为主的聚烯烃(PO)类隔膜、聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)、氨纶、芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜或纺丝膜等中的至少一种。例如，隔膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括聚乙烯、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-聚丙烯多孔复合膜等中的至少一种。任选地，基材层的至少一个表面上设置有表面处理层， 表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。例如，无机物层包括无机颗粒和粘结剂，所述无机颗粒没有特别限制，例如可以选自氧化铝、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。所述粘结剂没有特别限制，例如可以选自聚偏氟乙烯、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、聚四氟乙烯和聚六氟丙烯中的至少一种。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)等中的至少一种。
本申请的电化学装置还包括电解液，电解液包括锂盐和非水溶剂。在本申请对锂盐没有特别限制，只要能够实现本申请目的即可。例如，锂盐可以包括LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB或二氟硼酸锂中的至少一种。本申请对非水溶剂没有特别限制，只要能够实现本申请目的即可。例如，非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物的实例为碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物的实例为甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯或己内酯中的至少一种。上述醚化合物的实例为二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂的实例为二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。
本申请对第一电极组件和第二电极组件的结构没有特别限制，只要能够实现本申请目 的即可。例如，第一电极组件的结构可以包括卷绕结构或叠片结构。第二电极组件的结构可以为卷绕结构或叠片结构。在本申请中，第一电极组件和第二电极组件的结构可以相同或不同，例如，在本申请的一些实施例中，第一电极组件为卷绕结构，第二电极组件为卷绕结构。在本申请的另一些实施例中，第一电极组件为叠片结构，第二电极组件为叠片结构。在本申请的再一些实施例中，第一电极组件为叠片结构，第二电极组件为卷绕结构。在本申请的再一些实施例中，第一电极组件为卷绕结构，第二电极组件为叠片结构。
在本申请中，对包装壳没有特别限制，只要能够实现本申请的目的即可。例如，所述包装壳可以包括铝塑膜、铝壳、钢壳或塑料壳中的至少一种。
在本申请中，对包装壳的厚度没有特别限制，只要能够实现本申请的目的即可。例如，包装壳的厚度可以为60μm至500μm，优选为60μm至300μm，更优选为60μm至200μm。上述厚度的包装壳可以有效保护电化学装置的内部结构。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施例中，电化学装置可以包括但不限于：锂金属二次电池、锂离子二次电池(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：将第一正极极片、隔膜和第一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第一电极组件，将第一电极组件放入包装壳内；将第二正极极片、隔膜和第二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第二电极组件，将第二电极组件放入包装壳内；第一电极组件和第二电极组件之间用隔板分隔；将电解液注入包装壳并封口，得到电化学装置；或者，将第一正极极片、隔膜和第一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第一电极组件，将电极组件置入包装壳内；将第二正极极片、隔膜和第二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第二电极组件，将电极组件置入包装壳内；第一电极组件和第二电极组件之间用隔板分隔；将电解液注入包装壳并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装壳中，从而防止电化学装置内部的压力上升、过充放电。
本申请的第二方面提供了一种电子装置，其包含本申请前述任一实施方案中所述的电化学装置。因此，该电子装置具有较高的能量密度和良好的膨胀性能。
本申请提供了一种电化学装置及包含该电化学装置的电子装置，该电化学装置包括包装壳、第一电极组件和第二电极组件，包装壳设置有容纳腔体，第一电极组件和第二电极组件设置于容纳腔体内；第一电极组件包括第一正极极片和第一负极极片，第一正极极片包括第一正极集流体和设置于第一正极集流体至少一个表面上的第一正极活性材料层，第一负极极片包括第一负极集流体和设置于第一负极集流体至少一个表面上的第一负极活性材料层；第二电极组件包括第二正极极片和第二负极极片，第二正极极片包括第二正极集流体和设置于第二正极集流体至少一个表面上的第二正极活性材料层，第二负极极片包括第二负极集流体和设置于第二负极集流体至少一个表面上的第二负极活性材料层；第一负极活性材料层的涂布重量W 1f与第二负极活性材料层的涂布重量W 2f之间满足：30mg/1540.25mm 2≤W 2f－W 1f≤100mg/1540.25mm 2。该电化学装置具有较高的能量密度和良好的膨胀性能。
附图说明
为了更清楚地说明本申请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为本申请一种实施方案的的电化学装置内部结构示意图；
图2为图1中区域A的结构示意图；
图3为本申请一种实施方案的第一正极极片结构示意图；
图4为图3方案中的第一负极极片结构示意图。
具体实施方式中的附图标号如下：
10-包装壳，21-第一电极组件，211-第一正极极片，212-第一负极极片，22-第二电极组件，230-隔膜，31-第一腔体，32-第二腔体，40-隔板，51-第一正极极耳，52-第一负极极耳，100-电化学装置。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图和实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他技术方案，都属 于本申请保护的范围。
图1示出了本申请一种实施方案的电化学装置的内部结构示意图，如图1所示，电化学装置100包括：包装壳10、第一电极组件21和第二电极组件22，包装壳10设置有容纳腔体，容纳腔体包括第一腔体31和第二腔体32，第一腔体31和第二腔体32之间具有隔板40，第一电极组件21设置于第一腔体31，第二电极组件22设置于第二腔体32。
图2为图1中区域A的结构示意图，如图2所示，第一电极组件21的结构为多极耳结构，具体地，经第一正极极片211、隔膜230、第一负极极片212和隔膜230卷绕而成的多极耳结构卷芯中，第一正极极片211含有多个正极极耳(未图示)，第一负极极片212含有多个负极极耳52。图3示出了本申请一些实施例的第一正极极片的结构示意图，如图3所示，第一正极极耳51设置于第一正极极片211中正极活性材料层长度方向的两端之间。
图4示出了本申请一些实施例的第一负极极片的结构示意图，如图4所示，第一负极极耳52设置于第一负极极片212中负极活性材料层长度方向的两端之间。
如图3所示的第一正极极片211和如图4所示的第一负极极片212的结构为极耳中置结构。
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。
测试方法和设备
涂布重量的测试：
(1)用标准工具(面积1540.25mm 2)裁取极片样品，置于天平上称量重量，记为m1，然后将极片上的活性材料层洗净，将集流体置于天平上称量重量，记为m2；
(2)涂布重量计算：
若为单面涂布活性材料层的极片，涂布重量＝m1-m2。
若为双面涂布活性材料层的极片，涂布重量＝(m1-m2)/2。
压实密度的测试：
(1)截取一块规则极片，记录面积S1(cm 2)，同时记录极片厚度H1(μm)；
(2)对极片称重记录重量M1(mg)；
(3)将极片上活性材料层洗净，只剩集流体，对集流体进行称重，记录重量M2(mg)；同时测试集流体厚度H2(μm)；
(4)计算极片压密：压实密度(g/cm 3)＝10×(M1-M2)/(S1×(H2-H1))。
平均粒径的测试：
使用激光粒度仪测试第一负极活性材料的平均粒径Dv50 -1、第二负极活性材料的平均粒径Dv50 -2。
第一电极组件的容量占比和能量密度测试：
首先对第一电极组件和第二电极组件分别按照下述操作流程充电，再进行放电，得出第一电极组件和第二电极组件放电容量。
(1)第一电极组件充电：以6C充电至4.2V，再以4C充电至4.43V，再以3C充电至4.48V，恒压充电至1C；
(2)第二电极组件充电：以2C充电至4.2V，再以1.3C充电至4.45V，恒压充电至0.05C；
(3)第一电极组件放电：以1C恒流放电至3.0V，得出放电容量C1；
(4)第二电极组件放电：以0.5C恒流放电至3.0V，得出放电容量C2；
第一电极组件的容量占比：C1/(C1+C2)×100％。
锂离子电池在第二电极组件充电步骤完成后，用激光测厚仪测试锂离子电池的长L、宽W、高H，得到锂离子电池的体积V＝L×W×H。其体积能量密度(ED)可通过如下公式计算得到：ED(Wh/L)＝(C1+C2)/V。
厚度膨胀率的测试：
将荷电状态(SOC)＝0％的锂离子电池在激光测厚仪下测量厚度，记为T1；然后，将 锂离子电池中的第一电极组件和第二电极组件分别按<第一电极组件的容量占比和能量密度测试>中的方式进行充放电循环500圈，利用激光测厚仪测量最终的电池厚度为T500。厚度膨胀率(％)＝(T500-T1)/T1×100％。
实施例1-1
<第一负极极片的制备>
将第一负极活性材料石墨、丁苯橡胶和羧甲基纤维素钠按照质量比97:2:1进行混合，加入去离子水，调配成固含量为70％的浆料，并搅拌均匀。将浆料均匀涂覆在第一负极集流体铜箔的一个表面上，110℃条件下烘干，之后，在该第一负极集流体铜箔的另一个表面上重复以上步骤，即得到双面涂布第一负极活性材料层的第一负极极片。涂布完成后，将第一负极极片经冷压、裁切成规格为76mm×851mm的规格并焊接极耳后待用。其中，第一负极活性材料层的涂布重量W 1f为120mg/1540.25mm 2，第一负极活性材料层的压实密度D 1f为1.55g/cm 3，第一负极活性材料的比表面积BET 1为1.9m 2/g，第一负极活性材料的平均粒径Dv50 -1为10μm。
<第一正极极片的制备>
将第一正极活性材料钴酸锂(LiCoO 2)、导电剂导电炭黑、粘结剂聚偏二氟乙烯(PVDF)按照质量比97.5:1.0:1.5进行混合，加入N-甲基吡咯烷酮(NMP)，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在第一正极集流体铝箔的一个表面上，130℃条件下烘干，之后，在该第一正极集流体铝箔的另一个表面上重复以上步骤，即得到双面涂布第一正极活性材料层的正极极片。涂布完成后，将第一正极极片经冷压、裁切成74mm×867mm的规格并焊接极耳后待用。其中，第一正极活性材料层的涂布重量W 1z为220mg/1540.25mm 2，第一正极活性材料层的压实密度D 1z为4.05g/cm 3。
<第二负极极片的制备>
将第二负极活性材料石墨、丁苯橡胶和羧甲基纤维素钠按照质量比97:2:1进行混合，加入去离子水，调配成固含量为70％的浆料，并搅拌均匀。将浆料均匀涂覆在第二负极集流体铜箔的一个表面上，110℃条件下烘干，之后，在该第二负极集流体铜箔的另一个表面上重复以上步骤，即得到双面涂布第二负极活性材料层的第二负极极片。涂布完成后，将第二负极极片经冷压、裁切成规格为76mm×851mm并焊接极耳后待用。其中，第二负极活性材料层的涂布重量W 2f为150mg/1540.25mm 2，第二负极活性材料层的压实密度D 2f为 1.75g/cm 3，第二负极活性材料的比表面积BET 2为0.9m 2/g，第二负极活性材料的平均粒径Dv50 -2为20μm。
<第二正极极片的制备>
将第二正极活性材料钴酸锂(LiCoO 2)、导电剂导电炭黑、粘结剂聚偏二氟乙烯(PVDF)按照质量比97.5:1.0:1.5进行混合，加入N-甲基吡咯烷酮(NMP)，调配成固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在第二正极集流体铝箔的一个表面上，130℃条件下烘干，之后，在该第二正极集流体铝箔的另一个表面上重复以上步骤，即得到双面涂布第二正极活性材料层的正极极片。涂布完成后，将第二正极极片经冷压、裁切成74mm×867mm的规格并焊接极耳后待用。其中，第二正极活性材料层的涂布重量W 2z为280mg/1540.25mm 2，第二正极活性材料层的压实密度D 2z为4.18g/cm 3。
<电解液的制备>
在干燥氩气气氛中，将碳酸乙烯酯、碳酸甲乙酯和碳酸二乙酯以质量比EC︰EMC︰DEC＝30︰50︰20混合得到有机溶液，然后向有机溶剂中加入六氟磷酸锂溶解并混合均匀，得到六氟磷酸锂质量浓度为12.5％的电解液。
<隔膜的制备>
采用厚度为14μm的聚丙烯(PP)薄膜。
<第一电极组件的制备>
将上述制备的第一正极极片、隔膜、第一负极极片按顺序叠好，使隔膜处于第一正极极片和第一负极极片中间起到隔离的作用，并卷绕得到第一电极组件。其中，第一电极组件的结构为极耳中置结构。
<第二电极组件的制备>
将上述制备的第二正极极片、隔膜、第二负极极片按顺序叠好，使隔膜处于第二正极极片和第二负极极片中间起到隔离的作用，并卷绕得到第二电极组件。
<锂离子电池的制备>
将冲坑成型的一片外包装(厚度为150μm的铝塑膜)置于组装夹具内，坑面朝上，将 第一电极组件置于坑内。然后将第二电极组件放置于第一电极组件上。然后，将另一片外包装(厚度为150μm的铝塑膜)坑面朝下覆盖于第二电极组件之上，将第一电极组件和第二电极组件的正负极极耳均引出，留出注液口侧后热封外包装的其他位置，其中，热封温度为180℃，热封压力为0.5MPa。通过注液口注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。
实施例1-2至实施例1-7、对比例1至对比例2
除了根据表1调整第一负极活性材料层的涂布重量W 1f、第二负极活性材料层的涂布重量W 2f、第一正极活性材料层的涂布重量W 1z、第二正极活性材料层的涂布重量W 2z以外，其余与实施例1-1相同。
实施例2-1至实施例2-6
除了根据表2调整第一负极活性材料的比表面积BET 1、平均粒径Dv50 -1、第二负极活性材料的比表面积BET 2、平均粒径Dv50 -2以外，其余与实施例1-3相同。
实施例3-1至实施例3-3
除了根据表3调整第一负极活性材料层的涂布重量W 1f、第一正极活性材料层的涂布重量W 1z、第二负极活性材料层的涂布重量W 2f、第二负极活性材料的种类、第二负极活性材料的比表面积BET 2、第二正极活性材料层的涂布重量W 2z以外，其余与实施例1-3相同。
实施例1-1至实施例1-7、对比例1至对比例2的相关制备参数和性能参数如表1所示，实施例2-1至实施例2-6的相关制备参数和性能参数如表2所示，实施例3-1至实施例3-3的相关制备参数和性能参数如表3所示：
Figure PCTCN2021132408-appb-000001
Figure PCTCN2021132408-appb-000002
Figure PCTCN2021132408-appb-000003
从实施例1-1至实施例1-7、对比例1至对比例2可以看出，锂离子电池的膨胀性能和能量密度随着第一负极活性材料层的涂布重量W 1f与第二负极活性材料层的涂布重量W 2f的差值W 2f－W 1f的变化而变化。W 2f－W 1f在本申请范围内的锂离子电池，相对于W 2f－W 1f＜30的对比例1，具有更好的膨胀性能和能量密度，可能的原因在于：第二负极活性材料层的涂布重量W 2f较大，即其相对于第一负极活性材料层在相同面积下具有更多的活性材料，活性材料颗粒的堆积能够提供更多的孔隙，因此，第一电极组件在高倍率充放电循环过程中发生膨胀时，第二负极活性材料层能够为其提供充足的缓冲空间，由此，降低了电化学装置整体的体积增长率，从而改善了电化学装置的膨胀性能。而W 2f－W 1f＞100的对比例2，一方面具有较低的快充容量，无法满足高功耗应用的需求，另一方面，由于第一负极活性材料层的涂布重量W 1f相对于第二负极活性材料层的涂布重量W 2f过小，大大降低了锂离子电池整体的能量密度，且第一负极活性材料层的涂布重量W 1f<50mg/1540.25mm 2时，其表面与电解液发生副反应的程度增大，从而同样导致膨胀性能降低。
从实施例1-3、实施例2-1至实施例2-6可以看出，第一负极活性材料的比表面积BET 1在1.6m 2/g至2.0m 2/g的实施例1-3、实施例2-1至实施例2-2相比于实施例2-3，具有更加优异的膨胀性能，这是由于：第一负极活性材料的比表面积在上述范围内，一方面，能够满足高倍率充放电条件下，锂离子脱嵌速率的需要，从而降低析锂等副反应；另一方面，能够降低由于比表面过大带来在充放电过程中，负极活性材料表面与电解液的副反应的增加，从而改善膨胀性能。第二负极活性材料的比表面积BET 2在0.6m 2/g至1.1m 2/g的实施例1-3、实施例2-4至实施例2-5相比于实施例2-6，具有更高的能量密度，并且，由于在充放电过程中与电解液的接触面积较小，发生的副反应较少，因而能够具有较优的膨胀性能。
从实施例1-3、实施例3-1至实施例3-3可以看出，第二负极活性材料的种类为硅碳复合材料的实施例3-1至实施例3-3，在W 2f－W 1f在本申请范围内时，同样具有较优的膨胀性能，同时，能量密度更高。
需要说明的是，在本文中，诸如“第一”和“第二”等之类的关系术语仅仅用来将一个实体与另一个实体区分开来，而不一定要求或者暗示这些实体之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其它变体意在涵盖非排他性的包含，从而使得包括一系列要素的物品或者设备不仅包括那些要素，而且还包括没有明确列出的其它要素，或者是还包括为这种物品或者设备所固有的要素。
本说明书中的各个实施例均采用相关的方式描述，各个实施例之间相同相似的部分互相参见即可，每个实施例重点说明的都是与其它实施例的不同之处。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (10)

  1. 一种电化学装置，其包括：
    包装壳，所述包装壳设置有容纳腔体；
    第一电极组件和第二电极组件，所述第一电极组件和第二电极组件设置于所述容纳腔体内；
    所述第一电极组件包括第一正极极片和第一负极极片，所述第一正极极片包括第一正极集流体和设置于所述第一正极集流体至少一个表面上的第一正极活性材料层，所述第一负极极片包括第一负极集流体和设置于所述第一负极集流体至少一个表面上的第一负极活性材料层；
    所述第二电极组件包括第二正极极片和第二负极极片，所述第二正极极片包括第二正极集流体和设置于所述第二正极集流体至少一个表面上的第二正极活性材料层，所述第二负极极片包括第二负极集流体和设置于所述第二负极集流体至少一个表面上的第二负极活性材料层；
    所述第一负极活性材料层的涂布重量W 1f与所述第二负极活性材料层的涂布重量W 2f之间满足：30mg/1540.25mm 2≤W 2f－W 1f≤100mg/1540.25mm 2。
  2. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (1)所述第一负极活性材料层的涂布重量W 1f为50mg/1540.25mm 2至140mg/1540.25mm 2；
    (2)所述第一负极活性材料层的压实密度D 1f为1.5g/cm 3至1.8g/cm 3；
    (3)所述第二负极活性材料层的涂布重量W 2f为130mg/1540.25mm 2至170mg/1540.25mm 2；
    (4)所述第二负极活性材料层的压实密度D 2f为1.5g/cm 3至1.8g/cm 3。
  3. 根据权利要求1所述的电化学装置，其中，所述第一负极活性材料层包括第一负极活性材料，所述第二负极活性材料层包括第二负极活性材料，满足以下条件中的至少一者：
    (a)所述第一负极活性材料的比表面积BET 1为1.6m 2/g至2.0m 2/g；
    (b)所述第二负极活性材料的比表面积BET 2为0.6m 2/g至1.1m 2/g；
    (c)所述第一负极活性材料包括石墨或钛酸锂中的至少一种；
    (d)所述第二负极活性材料包括石墨或硅碳复合材料中的至少一种，所述硅碳复合材料中硅的质量百分含量W Si为0.1％至10％。
  4. 根据权利要求3所述的电化学装置，其中，所述第一负极活性材料的平均粒径Dv50 -1为5μm至15μm；所述第二负极活性材料的平均粒径Dv50 -2为16μm至25μm。
  5. 根据权利要求1所述的电化学装置，其中，所述第一正极活性材料层的涂布重量W 1z与所述第二正极活性材料层的涂布重量W 2z之间满足：50mg/1540.25mm 2≤W 2z－W 1z≤150mg/1540.25mm 2。
  6. 根据权利要求5所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    (e)所述第一正极活性材料层的涂布重量W 1z为150mg/1540.25mm 2至250mg/1540.25mm 2；
    (f)所述第一正极活性材料层的压实密度D 1z为3.5g/cm 3至4.5g/cm 3；
    (g)所述第二正极活性材料层的涂布重量W 2z为250mg/1540.25mm 2至315mg/1540.25mm 2；
    (h)所述第二正极活性材料层的压实密度D 2z为3.5g/cm 3至4.5g/cm 3。
  7. 根据权利要求1所述的电化学装置，其中，所述第一负极极片选自多极耳结构、极耳中置结构中的任一种。
  8. 根据权利要求1所述的电化学装置，其中，所述容纳腔体包括第一腔体和第二腔体，所述第一腔体和所述第二腔体之间具有隔板，所述第一电极组件设置于所述第一腔体，所述第二电极组件设置于所述第二腔体。
  9. 根据权利要求8所述的电化学装置，其中，所述隔板包括高分子材料或金属材料中的至少一种。
  10. 一种电子装置，其包括权利要求1至9中任一项所述的电化学装置。
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JP2006012703A (ja) * 2004-06-29 2006-01-12 Shin Kobe Electric Mach Co Ltd 二次電池
JP2011082099A (ja) * 2009-10-09 2011-04-21 Toshiba Corp 電池モジュール
CN108110221A (zh) * 2017-11-14 2018-06-01 合肥国轩高科动力能源有限公司 一种能量功率型锂离子电池的制备方法
CN108630995A (zh) * 2017-03-21 2018-10-09 株式会社东芝 二次电池、电池包以及车辆
CN112234247A (zh) * 2020-11-18 2021-01-15 珠海冠宇电池股份有限公司 一种锂离子电池

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006012703A (ja) * 2004-06-29 2006-01-12 Shin Kobe Electric Mach Co Ltd 二次電池
JP2011082099A (ja) * 2009-10-09 2011-04-21 Toshiba Corp 電池モジュール
CN108630995A (zh) * 2017-03-21 2018-10-09 株式会社东芝 二次电池、电池包以及车辆
CN108110221A (zh) * 2017-11-14 2018-06-01 合肥国轩高科动力能源有限公司 一种能量功率型锂离子电池的制备方法
CN112234247A (zh) * 2020-11-18 2021-01-15 珠海冠宇电池股份有限公司 一种锂离子电池

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