WO2024060128A1 - 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
WO2024060128A1
WO2024060128A1 PCT/CN2022/120504 CN2022120504W WO2024060128A1 WO 2024060128 A1 WO2024060128 A1 WO 2024060128A1 CN 2022120504 W CN2022120504 W CN 2022120504W WO 2024060128 A1 WO2024060128 A1 WO 2024060128A1
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Prior art keywords
hardened
area
isolation film
hardener
negative electrode
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PCT/CN2022/120504
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English (en)
French (fr)
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李学成
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宁德新能源科技有限公司
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Priority to PCT/CN2022/120504 priority Critical patent/WO2024060128A1/zh
Priority to CN202280010144.8A priority patent/CN116964854A/zh
Publication of WO2024060128A1 publication Critical patent/WO2024060128A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical energy storage, and in particular to electrochemical devices and electronic devices.
  • the internal isolation film of the lithium-ion battery shrinks, and the positive and negative electrode plates will be in direct contact with each other, causing an internal short circuit, resulting in a significant reduction in voltage, failure or direct smoke and fire. Therefore, the shrinkage of the isolation film will pose a serious threat to the safety of lithium-ion batteries and needs to be solved urgently.
  • Embodiments of the present application provide an electrochemical device, which includes a positive electrode piece, a negative electrode piece, and a separator.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece. In the width direction of the isolation film, the isolation film has a first area beyond the positive electrode piece.
  • the first area includes a first non-hardened area that overlaps with the negative electrode piece in the thickness direction of the isolation film, and extends beyond the negative electrode along the width direction.
  • a first hardened zone of the first hardener is provided on the edge of the pole piece. The hardness of the first hardened zone is greater than 1.0H, and the hardness of the first non-hardened zone is less than 1.0H.
  • the hardness of the first hardened zone is 1.5H-2.0H.
  • the separator in each battery rarely shrinks. If it is lower than the lower limit, the separator of a single battery will inevitably shrink in several places. If the hardness of the separator is too high, the hardness will be greater than 2.0H, the flexibility of the separator is relatively poor, the deformation is relatively large, and the edges are uneven, resulting in wavy edges, poor electrolyte filling, and the lithium ion diffusion channel is easily disconnected, resulting in lithium precipitation and deterioration of the cycle.
  • one or both sides of the first region include a first hardened zone, the width of the first hardened zone in the width direction is 0.2 mm to 2.5 mm, and the thickness of the first hardener on each side is 2 ⁇ m to 15 ⁇ m. In some embodiments, the width of the first hardened zone in the width direction is 0.2 mm to 2 mm, and the thickness of the first hardener on each side is 2 ⁇ m to 10 ⁇ m. The actual size of the battery, the preparation process, etc. restrict the width and thickness of the first hardened zone.
  • the size of the diaphragm exceeding the edge of the positive electrode and the size of the negative electrode pole piece exceeding the edge of the positive electrode pole piece will affect the size of the width of the first hardened zone.
  • the performance of the battery, energy density, etc. will be comprehensively considered to control various design parameters. Therefore, the size of the diaphragm exceeding the edge of the positive electrode and the size of the negative electrode pole piece exceeding the edge of the positive electrode pole piece are generally within the above range.
  • the first hardened areas of at least two layers of isolation films converge toward the middle or slope in the same direction.
  • the isolation film in the width direction of the isolation film, has a second area beyond the positive electrode piece, the first area and the second area are respectively located on both sides of the isolation film in the width direction, and the second area includes A second non-hardened area that overlaps with the negative electrode sheet in the thickness direction of the separator, and a second hardened area that extends beyond the edge of the negative electrode sheet along the width direction and is provided with a second hardener.
  • the hardness of the second hardened area is greater than The hardness of the second non-hardened zone. In some embodiments, the hardness of the second hardened zone is 1.5H-2.0H.
  • one or both sides of the second region of the isolation film include a second hardened zone, the width of the second hardened zone in the width direction is 0.2 mm to 2.5 mm, and the thickness of the second hardener on each side is 2 ⁇ m to 15 ⁇ m.
  • the first hardener and the second hardener each independently include at least one of UV glue, a mixture of SiO 2 and glue, or a mixture of Al 2 O 3 and glue.
  • An embodiment of the present application also provides an electronic device, including the above electrochemical device.
  • the isolation film in the width direction of the isolation film, has a first area beyond the positive electrode piece.
  • the first area includes a first non-hardened area that overlaps with the negative electrode piece in the thickness direction of the isolation film, and along the width direction The direction exceeds the edge of the negative electrode piece and is provided with a first hardened area of the first hardening agent, so that the hardness of the first hardened area is greater than 1.0H and the hardness of the first non-hardened area is less than 1.0H, which strengthens the resistance of the isolation film itself.
  • Impact force can resist the impact of electrolyte and ensure the safety performance of electrochemical devices when they fall.
  • Figures 1 to 5 show schematic cross-sectional views of portions of an electrochemical device according to some embodiments of the present application.
  • a glue wrapping solution or a low liquid retention solution is usually adopted.
  • U-shaped tape is applied to the head and tail of the electrode assembly.
  • the width of the tape is 5mm to 30mm.
  • the glue wrapping scheme takes into account the limited requirements of electrolyte infiltration and glue application.
  • the glue area of the head and tail end faces of the electrode assembly is ⁇ 60%.
  • the free electrolyte content in the electrode assembly is reduced, and the impact of the free electrolyte on the isolation membrane is reduced, thereby improving the shrinkage of the isolation membrane.
  • too low liquid retention volume will deteriorate the cycle performance of the electrochemical device.
  • the embodiment of the present application provides an electrochemical device, as shown in FIG. 1 .
  • the electrochemical device includes a positive electrode piece 10 , a negative electrode piece 11 and a separation film 12 .
  • the isolation film 12 is disposed between the positive electrode piece 10 and the negative electrode piece 11 . It should be understood that for simplicity purposes, only parts of the positive electrode plate 10 , the negative electrode plate 11 and the isolation film 12 are labeled in FIG. 1 .
  • the isolation film 12 in the width direction of the isolation film 12 , has a first region 121 beyond the positive electrode piece 11 , and the first area 121 includes a projection overlap with the negative electrode piece 11 in the thickness direction of the isolation film 12
  • the first non-hardened area 1211 and the first hardened area 1212 extending beyond the edge of the negative electrode piece 11 in the width direction and provided with the first hardening agent 13 .
  • the hardness of the first hardened area 1212 is greater than 1.0H, and the hardness of the first non-hardened area 1211 is less than 1.0H.
  • the area where the projection of the isolation film 12 overlaps with the negative electrode sheet 11 refers to the area of the isolation film 12 covered with the negative electrode sheet 11 or the area where the positive projection of the negative electrode sheet 11 on the isolation film 12 is located.
  • the hardener eg, the first hardener 13
  • the hardener can be sprayed out using an electric spray gun or a watering can, or the hardener can be applied using a glue coater, a brush, a scraper, or spraying. Then, the hardener can be dried in the range of 30°C to 130°C, or combined with ultraviolet light curing to harden the isolation film coated with the hardener.
  • a film hardness tester is used to measure the hardness of the isolation film 12 .
  • the performance of the electrochemical device can be improved.
  • the shrinkage of the isolation film 12 when dropped improves the safety performance of the electrochemical device.
  • the hardness of the first hardened zone 1212 is 1.5H ⁇ 2.0H.
  • one or both sides of the first region 121 of the isolation film 12 includes a first hardened area 1212 .
  • FIG. 3 shows a situation where both sides of the first area 121 include first hardened areas 1212 .
  • the width w1 of the first hardened zone 1212 in the width direction is 0.2 mm to 2.5 mm. If the width w1 is too small, the effect of the first hardened region 1212 on improving the shrinkage of the isolation film is relatively limited; if the width w1 is too large, the energy density of the electrochemical device will be adversely affected. In some embodiments, the width w1 of the first hardened zone 1212 in the width direction is 0.2 mm to 2 mm.
  • the width w1 of the first hardened zone 1212 in the width direction is 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm or other suitable values.
  • the thickness h1 of the first hardener 13 on each side is 2 ⁇ m to 15 ⁇ m. If the thickness h1 is too small, the effect of the first hardener 13 on improving the shrinkage of the isolation film is relatively limited; if the thickness h1 is too large, the energy density of the electrochemical device will be adversely affected. In some embodiments, the thickness h1 of the first hardener 13 on each side is 2 ⁇ m to 10 ⁇ m.
  • thickness h1 is 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, or other suitable values.
  • the width of the first hardening zone 1212 can be measured by an electron microscope, and the thickness of the first hardening agent 13 can be measured by a micrometer.
  • the thickness of the first hardening agent 13 total thickness - the thickness of the isolation film, if If both sides of the isolation film are coated with the first hardener 13, it needs to be divided by 2. It should be understood that when measuring the thickness of the first hardener 13, multiple points can be measured and then averaged.
  • the first hardened areas 1212 of the at least two layers of isolation film 12 are gathered toward the middle or inclined toward the same direction.
  • FIG. 4 shows a situation in which the first hardened areas 1212 of at least two layers of isolation films 12 are inclined in the same direction.
  • FIG. 5 shows a situation in which the first hardened areas 1212 of the at least two layers of isolation film 12 are gathered toward the middle.
  • a shaping block is used to shape the isolation film 12 in the first area 121 so that the isolation film 12 in this area is oriented and regularly moves from the outer ring to the inner ring. Come together to form a "V" cross state, or all face the same direction.
  • shaping may be performed before or after drying of the corresponding hardener.
  • the isolation film 12 in the width direction of the isolation film 12 , has a second area 122 beyond the positive electrode plate 10 , and the first area 121 and the second area 122 are respectively located in the isolation film 12 on both sides in the width direction. It should be understood that for simplicity purposes, only parts of the first area 121 and the second area 122 are labeled in FIG. 2 . In some embodiments, the first region 121 and the second region 122 are edge regions of the isolation film 12 in the width direction.
  • the second region 122 includes a second non-hardened region 1221 that overlaps with the negative electrode piece 11 in the thickness direction of the isolation film 12 , and extends beyond the edge of the negative electrode piece 11 along the width direction and is provided with a second non-hardened region 1221 .
  • the electrode assembly can be disassembled, and after peeling off the positive electrode piece 10 and the negative electrode piece 11, the corresponding area of the isolation film 12 (for example, the first Hardened area 1212, first non-hardened area 1211, second hardened area 1222, second non-hardened area 1221) are measured.
  • the hardness of the second hardened zone 1222 is greater than the hardness of the second non-hardened zone 1221 .
  • the shrinkage of the isolation film 12 when the electrochemical device is dropped can be improved, and the safety performance of the electrochemical device can be improved.
  • the hardness of the second hardened region 1222 is greater than 1.0H, and the hardness of the second non-hardened region 1221 is less than 1.0H.
  • the hardness of the second hardened zone 1222 is 1.5H to 2.0H.
  • one or both sides of the second region 122 of the isolation film 12 includes a second hardened region 1222 .
  • FIG. 3 shows a situation where both sides of the second area 122 include second hardened areas 1222 .
  • the width w2 of the second hardened zone 1222 in the width direction is 0.2 mm to 2.5 mm. If the width w2 is too small, the effect of the second hardened area 1222 on improving the shrinkage of the isolation film is relatively limited; if the width w2 is too large, the energy density of the electrochemical device will be adversely affected. In some embodiments, the width w2 of the second hardened zone 1222 in the width direction is 0.2 mm to 2 mm. In some embodiments, the width w2 of the second hardened zone 1222 in the width direction is 0.2 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm or other suitable values.
  • the thickness h2 of the second hardener 14 on each side is 2 ⁇ m to 15 ⁇ m. If the thickness h2 is too small, the effect of the second hardener 14 on improving the shrinkage of the isolation film is relatively limited; if the thickness h2 is too large, the energy density of the electrochemical device will be adversely affected. In some embodiments, the thickness h2 of the second hardener 114 on each side is 2 ⁇ m to 10 ⁇ m. In some embodiments, thickness h2 is 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, or other suitable values. The width of the second hardened zone 1222 and the thickness of the second hardener 14 can be measured using the same method as the first hardened zone 1212 and the first hardener 13 , which will not be described again.
  • both the first hardener 13 and the second hardener 14 are non-ester reagents.
  • non-ester reagents are more resistant to the electrolyte, thereby ensuring the stability of the first hardener 13 and the second hardener 14 and avoiding dissolution in the electrolyte.
  • the first hardener 13 and the second hardener 14 do not contain unsaturated functional groups and have a high oxidation potential, thereby further improving the performance of the first hardener 13 and the second hardener 14 in the electrolyte. Structural stability.
  • both the first hardener 13 and the second hardener 14 are resistant to electrolyte corrosion and are insoluble in the electrolyte, resistant to 4.8V high voltage and 110°C high temperature oxidative decomposition and aging, and do not undergo swelling, thus enabling Maintain hardness and bonding effect.
  • the first hardener 13 and the second hardener 14 each independently include at least one of UV glue, a mixture of SiO 2 and glue, or a mixture of Al 2 O 3 and glue.
  • the first hardener 13 and the second hardener 14 can adopt any suitable hardener available on the market, for example, a commercially available UV glue, a commercially available glue containing SiO 2 or a commercially available glue containing Al. 2 O 3 glue, these glues can be used as hardeners to improve the hardness of the corresponding areas of the isolation film 12 .
  • the corresponding hardener may be coated before or before winding.
  • the positive electrode sheet 10 includes a positive current collector and a positive active material layer disposed on the positive current collector.
  • the cathode active material layer is provided on one side or both sides of the cathode current collector.
  • the positive active material layer includes a positive active material.
  • the positive active material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, or lithium manganate.
  • the cathode active material layer may further include a conductive agent.
  • the conductive agent in the cathode active material layer may include at least one of conductive carbon black, Ketjen black, flake graphite, graphene, carbon nanotubes or carbon fibers.
  • the positive active material layer may further include a binder, and the binder in the positive active material layer may include carboxymethyl cellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyamide At least one of imide, polyamideimide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin or polyfluorene.
  • CMC carboxymethyl cellulose
  • the mass ratio of the cathode active material, conductive agent and binder in the cathode active material layer may be (80 ⁇ 99): (0.1 ⁇ 10): (0.1 ⁇ 10).
  • the thickness of the cathode active material layer may be 10 ⁇ m to 200 ⁇ m. It should be understood that the above is only an example, and the positive active material layer of the positive electrode may adopt any other suitable materials, thicknesses and mass ratios.
  • Al foil can be used as the positive electrode current collector.
  • the thickness of the cathode current collector may be 1 ⁇ m to 100 ⁇ m.
  • the positive active material layer may be coated on only a partial area of the current collector of the positive electrode.
  • the negative electrode sheet 11 includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.
  • the negative active material layer is provided on one or both sides of the negative current collector.
  • the negative active material layer includes a negative active material, and the negative active material may include at least one of graphite, hard carbon, silicon, silicon oxide, or organic silicon.
  • a conductive agent and a binder may also be included in the negative active material layer.
  • the conductive agent in the negative active material layer may include at least one of conductive carbon black, Ketjen black, flake graphite, graphene, carbon nanotubes or carbon fibers.
  • the binder in the negative active material layer may include carboxymethylcellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyimide, polyamideimide, polysilica At least one of oxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin or polyfluorene.
  • the mass ratio of the negative active material, the conductive agent and the binder in the negative active material layer may be (80 ⁇ 98): (0.1 ⁇ 10): (0.1 ⁇ 10). It should be understood that the above are only examples and any other suitable materials and mass ratios may be used.
  • the negative electrode current collector may be at least one of copper foil, nickel foil, or carbon-based current collector.
  • the isolation membrane 12 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid.
  • polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene.
  • polyethylene and polypropylene they have a good effect on preventing short circuits and can improve the stability of the battery through the shutdown effect.
  • the thickness of the isolation film ranges from about 5 ⁇ m to 50 ⁇ m.
  • the surface of the isolation membrane may further include a porous layer.
  • the porous layer is disposed on at least one surface of the base material of the isolation membrane.
  • the porous layer includes inorganic particles and a binder.
  • the inorganic particles are selected from aluminum oxide (Al 2 O 3 ), silicon oxide (SiO 2 ), magnesium oxide (MgO), titanium oxide (TiO 2 ), hafnium dioxide (HfO 2 ), tin oxide (SnO 2 ), ceria (CeO 2 ), nickel oxide (NiO) ), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, hydroxide At least one of calcium or barium sulfate.
  • the pores of the isolation film have a diameter in the range of about 0.01 ⁇ m to 1 ⁇ m.
  • the binder of the porous layer is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethylcellulose, poly At least one of vinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the porous layer on the surface of the isolation membrane can improve the heat resistance, oxidation resistance and electrolyte wetting performance of the isolation membrane, and enhance the adhesion between the isolation membrane and the pole piece.
  • the electrode assembly of the electrochemical device is a rolled electrode assembly, a stacked electrode assembly, or a folded electrode assembly.
  • the positive electrode sheet and/or the negative electrode sheet of the electrochemical device may be a multi-layer structure formed by rolling or stacking, or may be a single layer of positive electrode sheet, isolation film, or a single layer of negative electrode sheet stacked single layer structure.
  • the electrochemical device includes a lithium-ion battery, although the application is not limited thereto.
  • the electrochemical device may also include an electrolyte.
  • the electrolyte may be one or more of a gel electrolyte, a solid electrolyte, and an electrolyte solution, and the electrolyte solution includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , one or more of LiSiF 6 , LiBOB or lithium difluoroborate.
  • LiPF 6 was chosen for the lithium salt because it has high ionic conductivity and improves cycling characteristics.
  • the non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or a combination thereof.
  • the carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound, or a combination thereof.
  • chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl carbonate Ethyl ester (MEC) and its combinations.
  • chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl carbonate Ethyl ester (MEC) and its combinations.
  • Examples of the cyclic carbonate compound are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC) or combinations thereof.
  • fluorocarbonate compound are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate.
  • carboxylate compounds are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decanolactone, Valerolactone, mevalonolactone, caprolactone, methyl formate or combinations thereof.
  • ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxy ethane, 2-methyltetrahydrofuran, tetrahydrofuran or combinations thereof.
  • organic solvents examples include dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, methane Amides, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters or combinations thereof.
  • the positive electrode, separator, and negative electrode are wound or stacked in order to form an electrode piece, and then put into, for example, an aluminum-plastic film for packaging, and the electrolyte is injected to form, Encapsulated to make a lithium-ion battery. Then, the prepared lithium-ion battery was tested for performance.
  • electrochemical devices eg, lithium-ion batteries
  • electrochemical devices eg, lithium-ion batteries
  • Other methods commonly used in the art can be used without departing from the content disclosed in this application.
  • Embodiments of the present application also provide an electronic device including the above electrochemical device.
  • the electronic device in the embodiment of the present application is not particularly limited and may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, laptop computers, pen computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headsets, Video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Lighting appliances, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • Preparation of the positive electrode sheet Use the aluminum layer as the positive electrode current collector, dissolve the positive active material lithium cobalt oxide, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride in N-methyl in a weight ratio of 96:2.2:1.2 In a pyrrolidone (NMP) solution, a positive electrode active material layer slurry is formed, and the positive electrode active material layer slurry is coated on the positive electrode current collector with a coating thickness of 80 ⁇ m to obtain a positive electrode active material layer. Then after drying, cold pressing, and cutting, the positive electrode is obtained.
  • NMP pyrrolidone
  • Preparation of negative electrode sheets Dissolve artificial graphite, acetylene black, sodium carboxymethyl cellulose (CMC) and binder styrene-butadiene rubber in deionized water in a weight ratio of 96:1:1.5:1.5 to form negative electrode slurry material.
  • a copper foil with a thickness of 10 ⁇ m is used as the negative electrode current collector.
  • the negative electrode slurry is coated on the negative electrode current collector to a thickness of 120 ⁇ m, dried, and cut to obtain a negative electrode piece.
  • the isolation film base material is 8 ⁇ m thick polyethylene (PE), and a 2 ⁇ m alumina ceramic layer is coated on both sides of the isolation film base material. Finally, 2.5 ⁇ m alumina ceramic layer is coated on both sides of the isolation film base material. mg/cm 2 binder polyvinylidene fluoride (PVDF), dried.
  • PE polyethylene
  • PVDF polyvinylidene fluoride
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • V vinylene carbonate
  • Preparation of lithium-ion battery Stack the positive electrode sheet, isolation film, and negative electrode sheet in order, so that the isolation film is between the positive electrode sheet and the negative electrode sheet for isolation, and wind it to obtain the electrode assembly.
  • Coat a hardener Shin-Etsu Co., Ltd., Japan
  • the hardener is composed of SiO 2 and glue.
  • the width of the first hardened zone and the second hard zone are 0.5mm, the thickness is 5 ⁇ m, and the hardness of the hardened zone is 1.0H. Shape the isolation film coated with hardener into a V shape (that is, gather toward the center).
  • the electrode assembly is placed in an aluminum-plastic film, and after the moisture is removed at 80°C, the above-mentioned electrolyte is injected and packaged. After formation, degassing, trimming and other processes, a lithium-ion battery is obtained. Among them, the length of the electrode assembly is 91mm, the width is 66mm, and the thickness is 61mm.
  • the difference is that the hardener is not applied, but a conventional tape winding scheme is used, that is, after the electrode assembly is wound, a 10mm tape is attached to the head of the connecting tab, and two tapes are attached to the tail of the other side. A piece of 10mm tape and then encapsulated in aluminum plastic film.
  • the difference is that the hardener is applied to the first area and the second area of the separator on one side to form a first hardened area and a second hardened area beyond the negative electrode sheet.
  • the width of the first hardened zone and the second hard zone are 1.5mm, the thickness is 10 ⁇ m, and the hardness of the hardened zone is 1.4H.
  • the length of the electrode assembly is 85mm, the width is 63mm, and the thickness is 49mm.
  • the difference is that the width of the first hardened zone and the second hard zone are 2.5 mm, the thickness is 15 ⁇ m, and the hardness of the hardened zone is 1.58H.
  • the length of the electrode assembly is 90mm, the width is 63mm, and the thickness is 48mm.
  • the difference is that the first hardened zone and the second hardened zone have different hardnesses.
  • the lithium-ion battery leaks or catches fire and stops falling; measure and record the voltage before the drop and 24H after the drop; the voltage drop passing standard is: 24H voltage after the drop - voltage before the drop ⁇ 30mV;
  • the lithium-ion battery Disassemble the lithium-ion battery and calculate the shrinkage ratio of the isolation film.
  • the width of the isolation film > the width of the negative electrode piece > the width of the positive electrode piece. If the lithium ion battery is disassembled, the isolation film in the width direction If it shrinks to within the positive electrode piece, that is, when the width of the separator film is less than or equal to the width of the positive electrode piece, the lithium-ion battery is considered to be a lithium-ion battery with a shrinkage of the separator film.
  • Table 1 shows various parameters and evaluation results of Examples 1 to 7 and Comparative Example 1.
  • Example 1 By comparing Example 1 and Comparative Example 1, it can be seen that compared with the conventional glue wrapping scheme, by applying a hardener to harden the isolation film, the shrinkage of the isolation film can be basically completely suppressed, and the voltage drop failure and battery separator shrinkage during the drop process are improved.
  • the hardness of the isolation film is improved, which significantly improves the safety performance of lithium-ion batteries.
  • the hardness of the separator is too high, it will also affect the performance of the battery. If it is greater than 2.0H, the flexibility of the separator will be relatively poor. When assembling the battery, the separator will deform greatly and the edges will be irregular, resulting in wavy edges, poor electrolyte filling, and lithium ion diffusion channels. It is easy to disconnect, leading to lithium deposition and cycle deterioration, and the drop test is of little significance.
  • the glue wrapping in the existing glue wrapping scheme can also be omitted, effectively reducing the cost. After the glue wrapping is saved, the lithium-ion battery can be further improved. energy density.

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Abstract

本申请提供了电化学装置和电子装置。该电化学装置包括正极极片、负极极片和隔离膜。隔离膜设置于正极极片和负极极片之间。在隔离膜的宽度方向上，隔离膜具有超出正极极片的第一区域，第一区域包括在隔离膜的厚度方向上与负极极片投影重叠的第一非硬化区，及沿宽度方向超出负极极片的边缘且设置有第一硬化剂的第一硬化区，第一硬化区的硬度大于1.0H，第一非硬化区的硬度小于1.0H。如此，加强了隔离膜自身的抗冲击力，能够抵抗电解液冲击，保障电化学装置跌落时的安全性能。

Description

电化学装置和电子装置 技术领域
本申请涉及电化学储能领域，具体地，涉及电化学装置和电子装置。
背景技术
随着电化学装置(例如，锂离子电池)的在各类电子产品中的广泛应用，用户对于电化学装置的安全性能也提出了越来越高的要求，例如有时可能发生多次跌落后起火爆炸的情况。研究发现，跌落中电压降低或起火爆炸的原因主要是锂离子电池内部的隔离膜收缩而造成内短路。在锂离子电池的多次跌落中，游离电解液会反复冲击隔离膜。当电解液冲击力大于隔离膜束缚力时，锂离子电池内部隔离膜收缩，正极极片和负极极片会相互直接接触，造成内部短路，从而电压大幅降低失效或直接冒烟着火。因而隔离膜收缩会对锂离子电池安全存在严重威胁，需要迫切解决。
发明内容
本申请的实施例提供了一种电化学装置，该电化学装置包括正极极片、负极极片和隔离膜。隔离膜设置于正极极片和负极极片之间。在隔离膜的宽度方向上，隔离膜具有超出正极极片的第一区域，第一区域包括在隔离膜的厚度方向上与负极极片投影重叠的第一非硬化区，及沿宽度方向超出负极极片的边缘且设置有第一硬化剂的第一硬化区，第一硬化区的硬度大于1.0H，第一非硬化区的硬度小于1.0H。
在一些实施例中，第一硬化区的硬度为1.5H～2.0H。在此范围内，在跌落测试中，每个电池中隔膜的几乎很少收缩，如果低于下限值，单个电池的隔膜难免有几处发生收缩，如果隔膜硬度过高，硬度太高，大于2.0H，隔膜柔韧性比较差，形变比较大，边缘不整齐，导致波浪边，电解液填充不良，锂离子扩散通道容易断开，导致析锂从而循环恶化。
在一些实施例中，第一区域的单面或双面包括第一硬化区，第一硬化区在宽度方向上的宽度为0.2mm至2.5mm，每一面的第一硬化剂的厚度为2μm至15μm。在一些实施例中，第一硬化区在宽度方向上的宽度为0.2mm至2mm，每一面的第一硬化剂的厚度为2μm至10μm。电池的实际尺寸，制备工艺等制约了第一硬化区的宽度和厚度。特别是在宽度方向上，隔膜超过正极边缘的尺寸以及负极极片超过正极极片边缘的尺寸会影响第一硬化区宽度的大小，在实际生产制备电池过程中，会综合电池的性能，能量密度等，控制各项设计参数，因此如隔膜超过正极边缘的尺寸以及负极极片超过正极极片边缘的尺寸一般在上述范围内。
在一些实施例中，至少两层隔离膜的第一硬化区朝向中间聚拢或朝向相同的方向倾斜。
在一些实施例中，在隔离膜的宽度方向上，隔离膜具有超出正极极片的第二区域，第一区域和第二区域分别位于隔离膜的在宽度方向上的两侧，第二区域包括在隔离膜的厚度方向上与负极极片投影重叠的第二非硬化区，及沿宽度方向超出负极极片的边缘且设置有第二硬化剂的第二硬化区，第二硬化区的硬度大于第二非硬化区的硬度。在一些实施例中，第二硬化区的硬度为1.5H～2.0H。在一些实施例中，隔离膜的第二区域的单面或两面包括第二硬化区，第二硬化区在宽度方向上的宽度为0.2mm至2.5mm，每一面的第二硬化剂的厚度为2μm至15μm。在一些实施例中，第一硬化剂和第二硬化剂各自独立地包括UV胶、SiO 2与胶水的混合物或者Al 2O 3与胶水的混合物中的至少一种。
本申请的实施例还提供了一种电子装置，包括上述电化学装置。
本申请通过在隔离膜的宽度方向上，隔离膜具有超出正极极片的第一区域，第一区域包括在隔离膜的厚度方向上与负极极片投影重叠的第一非硬化区，及沿宽度方向超出负极极片的边缘且设置有第一硬化剂的第一硬化区，且使得第一硬化区的硬度大于1.0H，第一非硬化区的硬度小于1.0H，加强了隔离膜自身的抗冲击力，能够抵抗电解液冲击，保障电化学装置跌落时的安全性能。
附图说明
图1至图5示出了本申请的一些实施例的电化学装置的部分的示意截面图。
具体实施方式
下面的实施例可以使本领域技术人员更全面地理解本申请，但不以任何方式限制本申请。
为了改善隔离膜收缩的问题，通常采用绕胶方案或采用低保液方案。在绕胶方案中，在电极组件头尾贴U型胶纸，胶纸宽度为5mm至30mm，通过将部分隔离膜进行粘结，避免电解液直接冲击隔离膜，进而改善隔离膜收缩。然而，绕胶方案考虑到电解液浸润、贴胶能力受限要求，电极组件的头尾端面贴胶面积≤60％，还存在较大区域的端面无贴胶保护，易受到电解液直接冲击而成为薄弱点。在高保液下，隔离膜收缩更为严重。在低保液方案中，降低电极组件中的游离电解液含量，减小游离电解液对隔离膜的冲击，从而改善隔离膜收缩。然而，过低的保液量会恶化电化学装置的循环性能。
本申请的实施例提供了一种电化学装置，如图1所示，该电化学装置包括正极极片10、负极极片11和隔离膜12。在一些实施例中，隔离膜12设置于正极极片10和负极极片11之间。应该理解，为了简单的目的，图1中仅标示出部分正极极片10、负极极片11和隔离膜12。在一些实施例中，在隔离膜12的宽度方向上，隔离膜12具有超出正极极片11的第一区域121，第一区域121包括在隔离膜12的厚度方向上与负极极片11投影重叠的第一非硬化区1211，及沿宽度方向超出负极极片11的边缘且设置有第一硬化剂13的第一硬化区1212。在一些实施例中，第一硬化区1212的硬度大于1.0H，第一非硬化区1211的硬度小于1.0H。
在实施例中，隔离膜12的与负极极片11投影重叠的区域是指隔离膜12的覆盖有负极极片11的区域或负极极片11在隔离膜12上的正投影所在的区域。在一些实施例中，可以使用电动喷枪或者喷壶等将硬化剂(例如，第一硬化剂13)喷出，或者用涂胶机、刷板、刮板刮涂或喷涂等方式涂覆硬化剂。然后，可以在30℃至130℃范围内将硬化剂烘干，或者联用紫外光固化，使得涂有硬化剂的隔离膜变硬。在一些实施例中，采用薄膜硬度计来测量隔离膜12的硬度。
通过使得第一硬化区1212的硬度大于第一非硬化区1211的硬度，具体地第一硬化区1212的硬度大于1.0H，第一非硬化区1211的硬度小于1.0H，能够改善电化学装置在跌落时的隔离膜12的收缩，提升电化学装置的安全性能。
在一些实施例中，第一硬化区1212的硬度为1.5H～2.0H。通过提升隔离膜12的第一硬化区1212的硬度，可以改善在电化学装置跌落时隔离膜的收缩。
在一些实施例中，隔离膜12的第一区域121的单面或两面包括第一硬化区1212。图3示出了第一区域121的两面包括第一硬化区1212的情况。在一些实施例中，第一硬化区1212在宽度方向上的宽度w1为0.2mm至2.5mm。如果宽度w1太小，则第一硬化区1212改善隔离膜收缩的作用相对有限；如果宽度w1太大，则会不利地影响电化学装置的能量密度。在一些实施例中，第一硬化区1212在宽度方向上的宽度w1为0.2mm至2mm。在一些实施例中，第一硬化区1212在宽度方向上的宽度w1为0.2mm、0.5mm、1mm、1.5mm、2mm、2.5mm或其他合适的值。在一些实施例中，每一面的第一硬化剂13的厚度h1为2μm至15μm。如果厚度h1太小，则第一硬化剂13改善隔离膜收缩的作用相对有限；如果厚度h1太大，则会不利地影响电化学装置的能量密度。在一些实施例中，每一面的第一硬化剂13的厚度h1为2μm至10μm。在一些实施例中，厚度h1为2μm、4μm、6μm、8μm、10μm、12μm、15μm或其他合适的值。在一些实施例中，第一硬化区1212的宽度可以通过电子显微镜进行测量，第一硬化剂13的厚度可以通过万分尺测量，第一硬化剂13的厚度＝总厚度-隔离膜的厚度，如果隔离膜两侧均涂覆有第一硬化剂13，则需要除以2。应该理解，在测量第一硬化剂13的厚度时，可以取多个点进行测量，然后取平均值。
在一些实施例中，至少两层的隔离膜12的第一硬化区1212朝向中间聚拢或朝向相同的方向倾斜。图4示出了至少两层的隔离膜12的第一硬化区1212朝向相同的方向倾斜的情况。图5示出了至少两层的隔离膜12的第一硬化区1212朝向中间聚拢的情况。经过这种整形，一方面便利了电化学装置的封装，另一方面，在整形之后，不同层的一些硬化剂相互接触粘结，可以进一步改善跌落时隔离膜的收缩。在一些实施例中，在涂覆第一硬化剂的同 时，用整形块对第一区域121处的隔离膜12进行整形，使该区域的隔离膜12定向、有规律地由外圈向内圈聚拢，形成一个“V”字型交叉状态，或者均朝向同一个方向。在一些实施例中，可以在相应的硬化剂烘干之前或之后进行整形。
在一些实施例中，如图2所示，在隔离膜12的宽度方向上，隔离膜12具有超出正极极片10的第二区域122，第一区域121和第二区域122分别位于隔离膜12的在宽度方向上的两侧。应该理解，为了简单的目的，图2中仅标示了第一区域121和第二区域122的部分。在一些实施例中，第一区域121和第二区域122为隔离膜12在宽度方向上的边缘区域。在一些实施例中，第二区域122包括在隔离膜12的厚度方向上与负极极片11投影重叠的第二非硬化区1221，及沿宽度方向超出负极极片11的边缘且设置有第二硬化剂14的第二硬化区1222。在一些实施例中，在对隔离膜12的硬度进行测试时，可以将电极组件拆解开，将正极极片10和负极极片11剥离后，对隔离膜12的相应区域(例如，第一硬化区1212、第一非硬化区1211、第二硬化区1222、第二非硬化区1221)进行测量。在一些实施例中，第二硬化区1222的硬度大于第二非硬化区1221的硬度。同样地，通过使得第二硬化区1222的硬度大于第二非硬化区1221的硬度，能够改善电化学装置在跌落时的隔离膜12的收缩，提升电化学装置的安全性能。
在一些实施例中，第二硬化区1222的硬度大于1.0H，而第二非硬化区1221的硬度小于1.0H。第二硬化区1222的硬度为1.5H至2.0H。在一些实施例中，隔离膜12的第二区域122的单面或两面包括第二硬化区1222。图3示出了第二区域122的两面包括第二硬化区1222的情况。
在一些实施例中，第二硬化区1222在宽度方向上的宽度w2为0.2mm至2.5mm。如果宽度w2太小，则第二硬化区1222改善隔离膜收缩的作用相对有限；如果宽度w2太大，则会不利地影响电化学装置的能量密度。在一些实施例中，第二硬化区1222在宽度方向上的宽度w2为0.2mm至2mm。在一些实施例中，第二硬化区1222在宽度方向上的宽度w2为0.2mm、0.5mm、1mm、1.5mm、2mm、2.5mm或其他合适的值。在一些实施例中，每一面的第二硬化剂14的厚度h2为2μm至15μm。如果厚度h2太小，则第二硬化剂14改善隔离膜收缩的作用相对有限；如果厚度h2太大，则会不利地影响 电化学装置的能量密度。在一些实施例中，每一面的第二硬化剂114的厚度h2为2μm至10μm。在一些实施例中，厚度h2为2μm、4μm、6μm、8μm、10μm、12μm、15μm或其他合适的值。关于第二硬化区1222的宽度和第二硬化剂14的厚度的测量可以采用与第一硬化区1212和第一硬化剂13同样的方法进行测量，在此不再赘述。
在一些实施例中，第一硬化剂13和第二硬化剂14均为非酯类试剂。通常地，非酯类试剂能够更加耐受电解液，从而确保第一硬化剂13和第二硬化剂14的稳定性，避免溶解于电解液中。在一些实施例中，第一硬化剂13和第二硬化剂14不含有不饱和官能团，氧化电位较高，由此，能够进一步提升第一硬化剂13和第二硬化剂14在电解液中的结构稳定性。在一些实施例中，第一硬化剂13和第二硬化剂14均耐电解液腐蚀并且不溶于电解液、耐4.8V高电压和110℃高温氧化分解及老化，并且不发生溶胀现象，进而能够保持硬度和粘结效果。在一些实施例中，第一硬化剂13和第二硬化剂14各自独立地包括UV胶、SiO 2与胶水的混合物或者Al 2O 3与胶水的混合物中的至少一种。在一些实施例中，第一硬化剂13和第二硬化剂14可以采用市售的任何合适的硬化剂，例如，市售的UV胶、市售的含有SiO 2的胶水或市售的含有Al 2O 3的胶水，这些胶均可以用作硬化剂来提升隔离膜12的相应区域的硬度。在一些实施例中，针对卷绕型电极组件，可以在卷绕之前或之前进行相应的硬化剂的涂覆。
在一些实施例中，正极极片10包括正极集流体和设于正极集流体上的正极活性材料层。在一些实施例中，正极活性材料层设于正极集流体的一侧或两侧。在一些实施例中，正极活性材料层包括正极活性材料。在一些实施例中，正极活性材料包括钴酸锂、镍钴锰酸锂、镍钴铝酸锂或锰酸锂中的至少一种。在一些实施例中，正极活性材料层还可以包括导电剂。在一些实施例中，正极活性材料层中的导电剂可以包括导电炭黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，正极活性材料层还可以包括粘结剂，正极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。在一些实施例中，正极活性材料层中的正极活性材料、导电剂和 粘结剂的质量比可以为(80～99)：(0.1～10)：(0.1～10)。在一些实施例中，正极活性材料层的厚度可以为10μm至200μm。应该理解，以上所述仅是示例，正极的正极活性材料层可以采用任何其他合适的材料、厚度和质量比。
在一些实施例中，正极集流体可以采用Al箔，当然，也可以采用本领域常用的其他集流体。在一些实施例中，正极集流体的厚度可以为1μm至100μm。在一些实施例中，正极活性材料层可以仅涂覆在正极的集流体的部分区域上。
在一些实施例中，负极极片11包括负极集流体和设于负极集流体上的负极活性材料层。在一些实施例中，负极活性材料层设于负极集流体的一侧或两侧上。在一些实施例中，负极活性材料层包括负极活性材料，负极活性材料可以包括石墨、硬碳、硅、氧化亚硅或有机硅中的至少一种。在一些实施例中，负极活性材料层中还可以包括导电剂和粘结剂。在一些实施例中，负极活性材料层中的导电剂可以包括导电炭黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，负极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。在一些实施例中，负极活性材料层中的负极活性材料、导电剂和粘结剂的质量比可以为(80～98)：(0.1～10)：(0.1～10)。应该理解，以上所述仅是示例，可以采用任何其他合适的材料和质量比。在一些实施例中，负极集流体可以采用铜箔、镍箔或碳基集流体中的至少一种。
在一些实施例中，隔离膜12包括聚乙烯、聚丙烯、聚偏氟乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺或芳纶中的至少一种。例如，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯或超高分子量聚乙烯中的至少一种。尤其是聚乙烯和聚丙烯，它们对防止短路具有良好的作用，并可以通过关断效应改善电池的稳定性。在一些实施例中，隔离膜的厚度在约5μm至50μm的范围内。
在一些实施例中，隔离膜表面还可以包括多孔层，多孔层设置在隔离膜的基材的至少一个表面上，多孔层包括无机颗粒和粘结剂，无机颗粒选 自氧化铝(Al 2O 3)、氧化硅(SiO 2)、氧化镁(MgO)、氧化钛(TiO 2)、二氧化铪(HfO 2)、氧化锡(SnO 2)、二氧化铈(CeO 2)、氧化镍(NiO)、氧化锌(ZnO)、氧化钙(CaO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、碳化硅(SiC)、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。在一些实施例中，隔离膜的孔具有在约0.01μm至1μm的范围的直径。多孔层的粘结剂选自聚偏氟乙烯、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、羧甲基纤维素钠、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。隔离膜表面的多孔层可以提升隔离膜的耐热性能、抗氧化性能和电解质浸润性能，增强隔离膜与极片之间的粘结性。
在本申请的一些实施例中，电化学装置的电极组件为卷绕式电极组件、堆叠式电极组件或折叠式电极组件。在一些实施例中，电化学装置的正极极片和/或负极极片可以是卷绕或堆叠式形成的多层结构，也可以是单层正极极片、隔离膜、单层负极极片叠加的单层结构。
在一些实施例中，电化学装置包括锂离子电池，但是本申请不限于此。在一些实施例中，电化学装置还可以包括电解质。电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。锂盐选自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或者二氟硼酸锂中的一种或多种。例如，锂盐选用LiPF 6，因为它具有高的离子导电率并可以改善循环特性。
非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。
碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。
链状碳酸酯化合物的实例为碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)及其组合。所述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)、碳酸乙烯基亚乙酯(VEC)或者其组合。所述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、碳酸三氟甲基亚乙酯或者其组合。
羧酸酯化合物的实例为乙酸甲酯、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、己内酯、甲酸甲酯或者其组合。
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、四氢呋喃或者其组合。
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、和磷酸酯或者其组合。
在本申请的一些实施例中，以锂离子电池为例，将正极、隔离膜、负极按顺序卷绕或堆叠成电极件，之后装入例如铝塑膜中进行封装，注入电解液，化成、封装，即制成锂离子电池。然后，对制备的锂离子电池进行性能测试。
本领域的技术人员将理解，以上描述的电化学装置(例如，锂离子电池)的制备方法仅是实施例。在不背离本申请公开的内容的基础上，可以采用本领域常用的其他方法。
本申请的实施例还提供了包括上述电化学装置的电子装置。本申请实施例的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
下面列举了一些具体实施例和对比例以更好地对本申请进行说明，其中，采用锂离子电池作为示例。
实施例1
正极极片的制备：采用铝层作为正极集流体，将正极活性材料钴酸锂、导电剂导电炭黑、粘结剂聚偏氟乙烯按重量比96：2.2：1.2的比例溶于N-甲基吡咯烷酮(NMP)溶液中，形成正极活性材料层浆料，将正极活性材料层浆料涂覆于正极集流体上，涂覆厚度为80μm，得到正极活性材料层。然后经过干燥、冷压、裁切后得到正极。
负极极片的制备：将人造石墨、乙炔黑、羧甲基纤维素钠(CMC)和粘结剂丁苯橡胶按重量比96：1：1.5：1.5的比例溶于去离子水中，形成负极浆料。采用10μm厚度铜箔作为负极集流体，将负极浆料涂覆于负极集流体上，涂覆厚度为120μm，干燥，裁切后得到负极极片。
隔离膜的制备：隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg/cm 2的粘结剂聚偏氟乙烯(PVDF)，烘干。
电解液的制备：在含水量小于10ppm的环境下，将LiPF 6加入非水有机溶剂(碳酸乙烯酯(EC)：碳酸二乙酯(DEC)：碳酸亚丙酯(PC)：丙酸丙酯(PP)：碳酸亚乙烯酯(VC)＝20；30；20；28；2，重量比)，LiPF 6的浓度为1.15mol/L，混合均匀，得到电解液。
锂离子电池的制备：将正极极片、隔离膜、负极极片按顺序依次叠好，使隔离膜处于正极极片和负极极片中间起到隔离的作用，并卷绕得到电极组件。在隔离膜第一区域和第二区域双面涂布硬化剂(日本信越公司)，形成超出负极极片的第一硬化区和第二硬化区，硬化剂的成分为SiO 2和胶水。第一硬化区和第二硬区的宽度分别为0.5mm，厚度为5μm，硬化区硬度为1.0H。对涂布硬化剂的隔离膜进行V形(即朝向中间聚拢)整形。将电极组件置于铝塑膜中，在80℃下脱去水分后，注入上述电解液并封装，经过化成，脱气，切边等工艺流程得到锂离子电池。其中，电极组件的长度为91mm，宽度为66mm，厚度为61mm。
对比例1
依照实施例1，差别在于：不涂布硬化剂，而是采用常规的绕胶方案，即在电极组件卷绕之后，在连接极耳的头部贴10mm胶带，在另一侧的尾部贴两块10mm胶带，然后封装于铝塑膜中。
实施例2
依照实施例1，差别在于：在隔离膜的第一区域和第二区域单面涂布硬化剂，形成超出负极极片的第一硬化区和第二硬化区。第一硬化区和第二硬区的宽度分别为1.5mm，厚度为10μm，硬化区硬度为1.4H。电极组件的长度为85mm，宽度为63mm，厚度为49mm。
实施例3
依照实施例1，差别在于：第一硬化区和第二硬区的宽度分别为2.5mm，厚度为15μm，硬化区硬度为1.58H。电极组件的长度为90mm，宽度为63mm，厚度为48mm。
实施例4～7
依照实施例2，差别在于：第一硬化区和第二硬化区硬度不同。
下面描述本申请的各个参数的测试方法。
跌落测试方法：
1)将锂离子电池放入相应型号的跌落夹具；
2)1.5m 8轮跌落，每轮跌落10次；
3)锂离子电池出现漏液、着火停止跌落；测量记录跌落前，跌落后24H电压；电压降通过标准是：跌落后24H电压-跌落前电压＜30mV；
4)拆解锂离子电池，统计隔离膜收缩比例。在本申请的实施例中，通常地，在隔离膜的宽度方向上，隔离膜的宽度＞负极极片的宽度＞正极极片的宽度，如果锂离子电池拆解后，隔离膜在宽度方向上收缩至正极极片以内，即此时隔离膜的宽度小于等于正极极片的宽度，则认为该锂离子电池为隔离膜收缩锂离子电池。
5)隔膜收缩的处数统计：完成跌落实验后，统计所有电池隔膜发生收缩的部位有几处，每处是独立的，不连续的。以上测试取20个样品进行跌落测试，然后进行统计。
表1示出了实施例1至7以及对比例1的各个参数和评估结果。
表1
Figure PCTCN2022120504-appb-000001
通过比较实施例1与对比例1可知，相对于常规的绕胶方案，通过涂布硬化剂使隔离膜硬化，基本可以彻底抑制隔离膜收缩，改善了跌落过程中电压降失效、电池隔膜收缩，提升了隔离膜的硬度，显著提升了锂离子电池的安全性能。但是隔膜的硬度太大，也会影响电池的性能，若大于2.0H，隔膜柔韧性比较差，组装电池时隔膜形变比较大，边缘不整齐，导致波浪边，电解液填充不良，锂离子扩散通道容易断开，导致析锂从而循环恶化，跌落测试意义不大。
另外，相对于常规的绕胶方案，通过涂布硬化剂使隔离膜硬化，也可以省去现有绕胶方案中的绕胶，有效降低成本，绕胶节省后，还可以进一步提升锂离子电池的能量密度。
以上描述仅为本申请的较佳实施例以及对所运用技术原理的说明。本领域技术人员应当理解，本申请中所涉及的公开范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖由上述技术特征或其等同特征进行任意组合而形成的其它技术方案。例如上述特征与本申请中公开的具有类似功能的技术特征进行互相替换而形成的技术方案。

Claims (10)

  1. 一种电化学装置，其特征在于，包括：
    正极极片；
    负极极片；
    隔离膜，设置于所述正极极片和所述负极极片之间；
    其中，在所述隔离膜的宽度方向上，所述隔离膜具有超出所述正极极片的第一区域，所述第一区域包括在所述隔离膜的厚度方向上与所述负极极片投影重叠的第一非硬化区，及沿所述宽度方向超出所述负极极片的边缘且设置有第一硬化剂的第一硬化区，所述第一硬化区的硬度大于1.0H，所述第一非硬化区的硬度小于1.0H。
  2. 根据权利要求1所述的电化学装置，其特征在于，所述第一硬化区的硬度为1.5H～2.0H。
  3. 根据权利要求1所述的电化学装置，其特征在于，所述第一区域的单面或双面包括所述第一硬化区，在所述宽度方向上，所述第一硬化区的宽度为0.2mm至2.5mm，每一面的所述第一硬化剂的厚度为2μm至15μm。
  4. 根据权利要求3所述的电化学装置，其特征在于，所述第一硬化区在所述宽度方向上的宽度为0.2mm至2mm，每一面的所述第一硬化剂的厚度为2μm至10μm。
  5. 根据权利要求1所述的电化学装置，其特征在于，至少两层所述隔离膜的所述第一硬化区朝向中间聚拢或朝向相同的方向倾斜。
  6. 根据权利要求1所述的电化学装置，其特征在于，在所述隔离膜的宽度方向上，所述隔离膜具有超出所述正极极片的第二区域，所述第一区域和所述第二区域分别位于所述隔离膜的在所述宽度方向上的两侧，所述第二区域包括在所述隔离膜的厚度方向上与所述负极极片投影重叠的第二非硬化区，及沿所述宽度方向超出所述负极极片的边缘且设置有第二硬化剂的第二硬化区，第二硬化区的硬度大于第二非硬化区的硬度。
  7. 根据权利要求6所述的电化学装置，其特征在于，所述第二硬化区的硬度为1.5H～2.0H。
  8. 根据权利要求6所述的电化学装置，其特征在于，所述第二区域的单面或两面包括所述第二硬化区，所述第二硬化区在所述宽度方向上的宽度为0.2mm至2.5mm，每一面的所述第二硬化剂的厚度为2μm至15μm。
  9. 根据权利要求8所述的电化学装置，其特征在于，所述第一硬化剂和所述第二硬化剂各自独立地包括UV胶、SiO 2与胶水的混合物或者Al 2O 3与胶水的混合物中的至少一种。
  10. 一种电子装置，其特征在于，包括根据权利要求1至9中任一项所述的电化学装置。
PCT/CN2022/120504 2022-09-22 2022-09-22 电化学装置和电子装置 WO2024060128A1 (zh)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN203690386U (zh) * 2014-01-17 2014-07-02 东莞新能源科技有限公司 电芯及电化学装置
JP6054640B2 (ja) * 2012-05-30 2016-12-27 国立大学法人信州大学 セパレーターの製造方法、セパレーター製造装置及びセパレーター
CN109913161A (zh) * 2018-08-30 2019-06-21 拓迪化学(上海)有限公司 一种胶水及其制备方法以及胶水在电池电芯中的应用

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6054640B2 (ja) * 2012-05-30 2016-12-27 国立大学法人信州大学 セパレーターの製造方法、セパレーター製造装置及びセパレーター
CN203690386U (zh) * 2014-01-17 2014-07-02 东莞新能源科技有限公司 电芯及电化学装置
CN109913161A (zh) * 2018-08-30 2019-06-21 拓迪化学(上海)有限公司 一种胶水及其制备方法以及胶水在电池电芯中的应用

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