WO2025007715A1 - 电极组件、制备单面极片的方法、二次电池和电子设备 - Google Patents

电极组件、制备单面极片的方法、二次电池和电子设备 Download PDF

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WO2025007715A1
WO2025007715A1 PCT/CN2024/098628 CN2024098628W WO2025007715A1 WO 2025007715 A1 WO2025007715 A1 WO 2025007715A1 CN 2024098628 W CN2024098628 W CN 2024098628W WO 2025007715 A1 WO2025007715 A1 WO 2025007715A1
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sided
active material
material layer
electrode assembly
porous polymer
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English (en)
French (fr)
Inventor
周常通
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the field of battery technology, and in particular to an electrode assembly, a method for preparing a single-sided electrode sheet, a secondary battery and an electronic device.
  • Secondary batteries represented by lithium-ion batteries are widely used in digital electronic products, energy storage, drones, power tools, electric vehicles and other products due to their high energy density, long cycle life, high safety, fast charging capabilities and other characteristics.
  • laminated batteries can fully utilize battery space and have higher energy density.
  • the pole pieces need to be cold pressed and cut before stacking. After cold pressing, single-sided pole pieces (only one side of the current collector is coated with an active material layer) will bend and curl, resulting in the inability to proceed smoothly with subsequent processes. Therefore, it is necessary to improve the above problems.
  • the present application provides an electrode assembly, a method for preparing a single-sided electrode sheet, a secondary battery and an electronic device, aiming to improve the problem of bending and curling of the single-sided electrode sheet by combining a porous polymer layer on the surface of the active material layer of the single-sided electrode sheet.
  • the multiple first pole pieces in the electrode assembly include at least one single-sided first pole piece, and the single-sided first pole piece includes an active material layer arranged on one side of the current collector.
  • the first porous polymer layer restrains the extension of the active material layer and controls the release of internal stress in the active material layer, thereby improving the bending and curling problems of the single-sided first pole piece, thereby ensuring the smooth production of the single-sided first pole piece and improving the production efficiency of the electrode assembly.
  • the thickness d1 of the first porous polymer layer is substantially equal to the thickness d2 of the active material layer. In some embodiments, the thickness d1 of the first porous polymer layer and the thickness d2 of the active material layer satisfy: 25 ⁇ d2 / d1 ⁇ 40 .
  • the area S1 of the first porous polymer layer and the area S2 of the active material layer satisfy: 1.05 ⁇ S1 / S2 ⁇ 1.1 . In some embodiments, the area S1 of the first porous polymer layer and the area S2 of the active material layer satisfy: 1.05 ⁇ S1 / S2 ⁇ 1.09 .
  • the first porous polymer layer includes at least one of a polyethylene film, a polypropylene film, a polyethylene/polypropylene double-layer film, and a polypropylene/polyethylene/polypropylene three-layer film.
  • the pore size of the first porous polymer layer is 1 ⁇ m to 10 ⁇ m, and the porosity is 30% to 70%. In some embodiments, the pore size of the first porous polymer layer is 3 ⁇ m to 7 ⁇ m, and the porosity is 40% to 60%.
  • the first pole piece is a negative pole piece
  • the second pole piece is a positive pole piece
  • the single-sided first pole piece satisfies at least one of the following conditions:
  • the thickness of the current collector is 8 ⁇ m to 10 ⁇ m;
  • the active material layer has a thickness of 50 ⁇ m to 80 ⁇ m.
  • S10 providing a pole piece having an active material layer disposed on one side of a current collector
  • the step S20 specifically includes:
  • the first porous polymer layer is combined with the active material layer by cold pressing to obtain the single-sided electrode.
  • the present application provides a secondary battery, comprising: an electrolyte, and an electrode assembly according to any embodiment of the first aspect.
  • the present application provides a secondary battery, comprising: a separator, an electrolyte, and a single-sided electrode prepared by the method described in any embodiment of the second aspect.
  • a fifth aspect is an electronic device, comprising: a secondary device according to any one of the embodiments of the third aspect or the fourth aspect; Battery.
  • FIG. 2 is a schematic diagram of the structure of a single-sided first electrode sheet in an electrode assembly according to an embodiment of the present application.
  • first and second are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality” is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
  • the battery may include a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery or a magnesium-ion battery, etc., and the embodiments of the present application do not limit this.
  • the battery may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this.
  • a single-sided pole piece refers to a pole piece having an active material layer only on one side of a current collector
  • a corresponding double-sided pole piece refers to a pole piece having an active material layer on both sides of a current collector.
  • the pole pieces need to be cold pressed and cut before stacking. After cold pressing, the single-sided pole pieces are prone to bending and curling.
  • the specific schematic diagram is shown in Figure 1. Due to the different elongation rates of the active material layer 2 and the current collector 1, as the internal stress in the active material layer 2 is released, the active material layer 2 will bend and curl toward the current collector 1, resulting in the subsequent pole piece cutting process cannot be carried out smoothly, thereby affecting the production of the battery. Efficiency, reduced production capacity, will also reduce including.
  • the binder content on the surface of the active material layer will be significantly reduced, and the roughness will increase, resulting in a decrease in the bonding force between the active material layer of the single-sided pole piece and the isolation membrane during the subsequent hot pressing process, and then the distance between the active material layer and the other side of the isolation membrane becomes larger, resulting in a longer ion transmission path during the battery charging and discharging process. Long-term cycling may cause problems such as lithium precipitation and abnormal expansion, and the reliability of the battery is reduced.
  • the present application provides an electrode assembly, a method for preparing a single-sided pole piece, a secondary battery and an electronic device, wherein the electrode assembly provided by the present application includes a single-sided first pole piece, and a first porous polymer layer is provided on the side of the active material layer in the single-sided first pole piece opposite to the current collector, so as to improve the problem of bending and curling of the single-sided pole piece.
  • the electrode assembly provided by the present application includes a single-sided first pole piece, and a first porous polymer layer is provided on the side of the active material layer in the single-sided first pole piece opposite to the current collector, so as to improve the problem of bending and curling of the single-sided pole piece.
  • the present application provides an electrode assembly, comprising: a plurality of first electrode sheets, the plurality of first electrode sheets comprising at least one single-sided first electrode sheet, the single-sided first electrode sheet comprising a current collector and an active material layer, the active material layer being arranged on one side of the current collector, and a first porous polymer layer being arranged on the side of the active material layer opposite to the current collector; and a plurality of second electrode sheets, the second electrode sheets having opposite polarity to the first electrode sheets; and an isolation membrane, the isolation membrane comprising a second porous polymer layer; wherein the first electrode sheets and the second electrode sheets are alternately stacked, and the isolation membrane is arranged between the first electrode sheets and the second electrode sheets.
  • the single-sided electrode After the single-sided electrode is cold pressed, due to the large difference in elongation between the active material layer and the current collector, as the internal stress in the active material layer is released, the single-sided electrode will bend and curl.
  • the main reason for this phenomenon is that the active material layer has a certain thickness. Under the action of the bonding force, the current collector with a smaller elongation will restrain the extension of the active material layer close to the current collector, while the side of the active material layer opposite to the current collector is not restrained, so bending and curling will occur as the stress is released.
  • the first porous polymer layer In the single-sided first electrode of the present application, after the first porous polymer layer is arranged on the side of the active material layer opposite to the current collector, since the elongation of the first porous polymer layer is smaller than that of the active material layer, the first porous polymer layer will restrain the extension of the side of the active material layer opposite to the current collector. Therefore, under the joint action of the first porous polymer layer and the current collector, the problem of bending and curling of the single-sided first electrode can be effectively improved, which is beneficial to improving the production efficiency of the electrode assembly. It should also be noted that due to the porous structure of the first porous polymer layer, while exerting the above-mentioned effects, it has little effect on ion transport and will not significantly reduce the electrical performance of the battery.
  • the structural schematic diagram of the single-sided first pole piece is shown in FIG2 , where an active material layer 2 is bonded to one side of the current collector 1, and a first porous polymer layer 3 is bonded to the surface of the active material layer.
  • the single-sided first pole piece is merely exemplary, and the single-sided first pole piece in the present application may also include other functional film layers, for example, in some embodiments, a conductive coating (e.g., composed of an adhesive and a conductive agent) may also be provided between the current collector 1 and the active material layer 2.
  • a conductive coating e.g., composed of an adhesive and a conductive agent
  • the thickness d1 of the first porous polymer layer and the thickness d2 of the active material layer satisfy: 20 ⁇ d2 / d1 ⁇ 50 .
  • the relationship between the thickness d1 of the first porous polymer layer and the thickness d2 of the active material layer is further optimized. It can be understood that the greater the relative thickness of the first porous polymer layer, the greater the binding effect on the side of the active material layer opposite to the current collector, and at the same time, it will also lead to a decrease in energy density and electrical performance. Therefore, when the thickness d1 of the first porous polymer layer and the thickness d2 of the active material layer satisfy: 20 ⁇ d2 / d1 ⁇ 50 , the shape of the single-sided first pole piece in the electrode assembly is more stable, further improving the production efficiency of the electrode assembly. In addition, the electrical performance of the battery containing the electrode assembly is better at this time.
  • d2 / d1 can be 25, 27, 29, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, or within the range of any of the above values, preferably, 25 ⁇ d2 / d1 ⁇ 40 .
  • the area S 1 of the first porous polymer layer and the area S 2 of the active material layer satisfy: 1.05 ⁇ S 1 /S 2 ⁇ 1.1.
  • the relationship between the area S1 of the first porous polymer layer and the area S2 of the active material layer is further optimized.
  • the area of the first porous polymer layer By controlling the area of the first porous polymer layer to be appropriately higher than the area of the active material layer, the extension of the active material layer on the opposite side of the current collector can be more effectively restrained, the stability of the shape of the single-sided first electrode sheet can be improved, and the In addition, during the battery cycle, even if the first porous polymer layer shrinks, the shape of the single-sided first electrode sheet can still be kept stable, thereby improving the electrical performance of the secondary battery.
  • S 1 /S 2 can be 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, or any of the above values.
  • 1.05 ⁇ S 1 /S 2 ⁇ 1.09.
  • the first porous polymer layer includes at least one of a polyethylene film, a polypropylene film, a polyethylene/polypropylene double-layer film, and a polypropylene/polyethylene/polypropylene triple-layer film.
  • the first porous polymer layer can include a polymer film having a smaller elongation than the active material layer and a porous structure, and those skilled in the art can select any porous polymer film in the prior art that meets the above requirements as the first porous polymer layer according to actual needs.
  • the first porous polymer layer has a pore size of 1 ⁇ m to 10 ⁇ m and a porosity of 30% to 70%.
  • the pore size and porosity of the first porous polymer layer are further defined. Since the first porous polymer layer is arranged on the opposite side of the active material layer to the current collector, ions need to pass through the first porous polymer layer to enter the active material layer during the charge and discharge process of the battery. Therefore, the pore size and porosity of the first porous polymer layer have a certain influence on the electrical properties of the battery containing the electrode assembly. When the pore size of the first porous polymer layer is 1 ⁇ m to 10 ⁇ m and the porosity is 30% to 70%, the electrical properties of the battery containing the electrode assembly are better.
  • the pore size of the first porous polymer layer can be 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, or within the range of any of the above values; the porosity can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or within the range of any of the above values.
  • the pore size of the first porous polymer layer may be 3 ⁇ m to 7 ⁇ m, and the porosity may be 40% to 60%.
  • the topmost and bottommost layers of the electrode assembly are configured as single-sided first pole sheets, and the plurality of first pole sheets further include double-sided first pole sheets, which are stacked in the middle layer of the electrode assembly.
  • the plurality of first pole pieces also include a double-sided first pole piece, and the double-sided first pole piece is stacked in the middle layer of the electrode assembly.
  • the double-sided first pole piece can reduce the number of layers of the current collector under certain conditions of the active material layer, thereby improving the energy density of the battery;
  • the top and bottom layers of the electrode assembly are set as single-sided first pole pieces. This is because if the double-sided first pole piece is set at the top or bottom layer, there will always be one side of the active material layer that cannot participate in the charge and discharge cycle, which will increase the cost and reduce the battery energy density. Therefore, the energy density of the battery can be effectively improved by the electrode assembly set as above.
  • the plurality of second pole pieces may all be double-sided second pole pieces, and the resulting battery has a higher Energy density.
  • the polarity of the first pole piece and the second pole piece in the present application may not be further limited, that is, whether the single-sided first pole piece is a negative pole piece or a positive pole piece, the beneficial effects of the single-sided first pole piece mentioned above can be achieved.
  • the first electrode piece is a negative electrode piece
  • the second electrode piece is a positive electrode piece
  • the polarities of the first pole piece and the second pole piece are respectively limited.
  • the first pole piece is a negative pole piece.
  • the energy density is lower than when the first pole piece is a positive pole piece, relatively speaking, the battery has higher reliability and can be applied to different usage environments.
  • the first pole piece is a positive pole piece
  • the second pole piece is a negative pole piece
  • the polarities of the first pole piece and the second pole piece are also limited respectively. It can be understood that when the topmost layer and the bottommost layer of the electrode assembly are respectively single-sided first pole pieces, the energy density of the battery can be more effectively improved.
  • the single-sided first pole piece satisfies at least one of the following conditions:
  • the thickness of the current collector is 8 ⁇ m to 10 ⁇ m;
  • the thickness of the active material layer is 50 ⁇ m to 80 ⁇ m.
  • the thickness of the current collector and the thickness of the active material layer are further limited.
  • a current collector that is too thick will reduce the energy density of the battery, while a current collector that is too thin has low strength.
  • the current collector thickness is 8 ⁇ m to 10 ⁇ m, the stability of the single-sided first pole piece in the electrode assembly is better, the production efficiency of the electrode assembly is higher, and the battery containing the electrode assembly has a better energy density.
  • An overly thick active material layer has greater ductility, which may reduce the stability of the first single-sided pole piece.
  • An overly thin active material layer is not conducive to the improvement of energy density.
  • the thickness of the active material layer is 50 ⁇ m to 80 ⁇ m, the stability of the first single-sided pole piece and the energy density of the battery containing the electrode assembly can be better taken into account.
  • the thickness of the active material layer increases, the thickness of the first porous polymer layer can be appropriately increased to improve the stability of the first single-sided pole piece. Since the thickness of the first porous polymer layer is too high, it will obviously affect ion transmission, so the thickness of the active material layer should not be too high.
  • the thickness of the current collector can be 8 ⁇ m, 8.5 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m, or within the range of any of the above values;
  • the thickness of the active material layer can be 50 ⁇ m, 52 ⁇ m, 55 ⁇ m, 58 ⁇ m, 60 ⁇ m, 65 ⁇ m, 70 ⁇ m, 72 ⁇ m, 75 ⁇ m, 78 ⁇ m, 80 ⁇ m, or within the range of any of the above values.
  • the isolation film has a continuously bent structure.
  • the isolation film can have a continuous bending structure. More specifically, the isolation film The membrane includes a plurality of straight sections arranged along the stacking direction and a bent section connecting two adjacent straight sections, and the first pole piece and the second pole piece are stacked in sequence in a manner of being isolated from each other by the straight sections of the isolation membrane.
  • the electrode assembly includes an isolation membrane, and the isolation membrane has a continuous bending structure, including a plurality of straight sections arranged along the stacking direction and a bent section connecting two adjacent straight sections, and the first pole piece and the second pole piece are isolated from each other by the straight sections of the isolation membrane, and are alternately stacked.
  • the electrode assembly includes a plurality of isolation membranes, and the isolation membranes may have a straight structure.
  • the first pole piece and the second pole piece are isolated from each other by the isolation membranes and are alternately stacked.
  • the second porous polymer layer in the isolation membrane is not limited in the present application.
  • the material of the second porous polymer layer can be selected from one or more of polyethylene, polypropylene, and polyvinylidene fluoride, but is not limited to these.
  • the second porous polymer layer can be a single-layer film or a multi-layer composite film. When the isolation membrane is a multi-layer composite film, the materials of each layer are the same or different. In some embodiments, a ceramic coating or a metal oxide coating can also be provided on the isolation membrane.
  • the present application does not limit the current collector, and a metal foil, a porous metal plate or a composite current collector can be used.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the current collector is aluminum foil.
  • the materials, processes and preparation methods of the active material layer in the single-sided first pole piece in the present application may include any technology known in the prior art.
  • the active material layer includes active material, conductive agent, and binder.
  • the active material, conductive agent, and binder may be those commonly used in the art, and there is no specific limitation on the specific type.
  • the active material may be a positive electrode active material
  • the positive electrode active material may use one or more of lithium transition metal oxides, lithium-containing phosphates with olivine structures, and their respective modified compounds.
  • the modified compounds of the above-mentioned positive electrode active materials may be doping modification, surface coating modification, or doping and simultaneous surface coating modification of the positive electrode active material.
  • the lithium transition metal oxide may include one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds.
  • the lithium-containing phosphate with olivine structure may include one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and modified compounds thereof.
  • These positive electrode active materials may be used alone or in combination of two or more.
  • the active material may also be a negative electrode active material, and may include one or more of a carbonaceous material, a metal compound that can be alloyed with lithium, a metal oxide that can be doped with or not doped with lithium, and a composite material including a metal compound and a carbonaceous material.
  • the binder can use one or more of polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, polyacrylonitrile, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, carboxymethyl cellulose, styrene-butadiene rubber, fluororubber, or various copolymers thereof.
  • EPDM ethylene-propylene-diene polymer
  • sulfonated EPDM carboxymethyl cellulose
  • styrene-butadiene rubber fluororubber, or various copolymers thereof.
  • binders can be used alone or in combination of two or more.
  • the conductive agent may include one or more of graphene, mesh graphite fiber, carbon nanotube, Ketjen black, graphite fiber or nano-particle conductive carbon.
  • the electrode assembly in the present application can be prepared according to conventional methods in the art. For example, in some embodiments, a plurality of first pole pieces, a plurality of second pole pieces and a separator are stacked in a zigzag shape to obtain an electrode assembly. In some embodiments, a plurality of first pole pieces, a plurality of second pole pieces and a plurality of separators are stacked in sequence to obtain an electrode assembly.
  • the present application provides a method for preparing a single-sided pole piece, comprising the following steps:
  • S10 providing a pole piece having an active material layer disposed on one side of a current collector
  • a first porous polymer layer is combined on the active material layer, and the resulting single-sided pole piece is not prone to bending or curling problems, thereby ensuring smooth production of the single-sided pole piece.
  • the single-sided electrode sheet can be a positive electrode sheet or a negative electrode sheet.
  • the first porous polymer layer, the current collector and the active material layer can be selected with reference to any embodiment of the first aspect, and will not be described in detail here.
  • the pole piece with an active material layer disposed on one side of the current collector can be prepared according to conventional methods in the art.
  • the active material, the conductive agent and the binder are dispersed in a solvent to obtain an active slurry, the active slurry is coated on one side of the current collector, and the active material layer is obtained after drying, that is, the pole piece with an active material layer disposed on one side of the current collector is obtained.
  • the solvent may be water, dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec-butanol), 1-methyl-2-propanol (tert-butanol), pentanol, hexanol, heptanol or octanol; a glycol such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propylene glycol, 1,3- One or more of butanediol, 1,5-pentanediol, hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorb
  • the pole piece having the active material layer disposed on one side of the current collector further includes a conductive coating sandwiched between the current collector and the active material layer and disposed on one side of the current collector.
  • step S20 specifically includes:
  • the first porous polymer layer is combined with the active material layer by cold pressing to obtain a single-sided electrode.
  • the bonding method of the first porous polymer layer and the active material layer is specifically defined. Since the active material layer contains a binder, the first porous polymer layer and the active material layer can be stably bonded by cold pressing. Better bonding force can better restrain the extension of the active material layer and improve the stability of the single-sided electrode.
  • cold pressing is a commonly used process in the preparation of pole pieces in order to obtain an active material layer with a suitable compaction density. Therefore, the process of combining the first porous polymer layer with the active material layer can be carried out simultaneously with cold pressing.
  • no additional steps need to be added, thereby improving production efficiency.
  • carrying out the processes simultaneously can significantly improve the stability of the single-sided pole pieces and ensure the smooth progress of the process.
  • FIG3 a schematic diagram of a method for preparing a single-sided electrode sheet is shown in FIG3 , in which a electrode sheet having an active material layer disposed on one side of the current collector (the single-sided coated electrode sheet in the figure) and a first porous polymer film are unwound simultaneously, and rolled between an upper roller and a lower roller, and the active material layer in the electrode sheet and the first porous polymer film are combined by cold pressing, and finally rolled up to obtain a single-sided electrode sheet.
  • the single-sided pole piece can be cut and used as the single-sided first pole piece in any embodiment of the first aspect.
  • the present application provides a secondary battery, comprising: an electrolyte, and an electrode assembly according to any embodiment of the first aspect.
  • the secondary battery includes the electrode assembly of any embodiment of the first aspect, thereby having the beneficial effects of any embodiment of the first aspect.
  • the electrolyte plays a role in conducting active ions between the first electrode piece and the second electrode piece.
  • the electrolyte that can be used in the secondary of the present application can be an electrolyte known in the prior art.
  • the electrolyte may include an organic solvent, an electrolyte salt, and optional additives.
  • the types of the organic solvent, the lithium salt, and the additives are not particularly limited and may be selected according to requirements.
  • the secondary battery is a lithium ion battery
  • the electrolyte salt may include a lithium salt.
  • the lithium salt includes, but is not limited to, at least one of LiPF 6 (lithium hexafluorophosphate), LiBF 6 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiFSI (lithium bisfluorosulfonyl imide), LiTFSI (lithium bistrifluoromethanesulfonyl imide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate borate), LiBOB (lithium dioxalate borate), LiPO 2 F 2 (lithium difluorophosphate), LiDFOP (lithium difluorooxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate).
  • the above lithium salts may be used alone or in combination of two or more
  • the secondary battery is a sodium ion battery
  • the electrolyte salt may include a sodium salt.
  • the sodium salt may be selected from at least one of NaPF 6 , NaClO 4 , NaBCl 4 , NaSO 3 CF 3 and Na(CH 3 )C 6 H 4 SO 3 .
  • the organic solvent includes but is not limited to ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), cyclopentane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sul
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the additives include but are not limited to fluoroethylene carbonate (FEC), vinylene carbonate (VC), At least one of vinyl carbonate (VEC), vinyl sulfate (DTD), propylene sulfate, vinyl sulfite (ES), 1,3-propane sultone (PS), 1,3-propylene sultone (PST), sulfonate cyclic quaternary ammonium salt, succinic anhydride, succinonitrile (SN), adiponitrile (AND), tris(trimethylsilyl) phosphate (TMSP), and tris(trimethylsilyl) borate (TMSB).
  • FEC fluoroethylene carbonate
  • VEC vinylene carbonate
  • DTD vinyl sulfate
  • ES vinyl sulfite
  • PS 1,3-propane sultone
  • PST 1,3-propylene sultone
  • succinic anhydride succinonitrile
  • SN succinon
  • the electrolyte can be prepared according to conventional methods in the art.
  • an organic solvent, an electrolyte salt, and an optional additive can be mixed uniformly to obtain an electrolyte.
  • the electrolyte salt and the optional additive are added to the organic solvent and mixed uniformly to obtain the electrolyte; or, the electrolyte salt is first added to the organic solvent, and then the optional additive is added to the organic solvent and mixed uniformly to obtain the electrolyte.
  • the present application provides a secondary battery, comprising: a separator, an electrolyte, and a single-sided electrode prepared according to the method of any embodiment of the second aspect.
  • the secondary battery includes the single-sided pole piece of any embodiment of the second aspect, thereby having the beneficial effects of any embodiment of the second aspect.
  • the single-sided electrode sheet prepared by the method of any embodiment of the second aspect is used as the positive electrode sheet.
  • the embodiment of the single-sided electrode sheet as the positive electrode sheet has been described in detail above and will not be repeated here.
  • the single-sided electrode sheet prepared by the method of any embodiment of the second aspect is used as the negative electrode sheet.
  • the embodiment of the single-sided electrode sheet as the negative electrode sheet has been described in detail above and will not be repeated here.
  • an electronic device includes: a secondary battery according to any one embodiment of the third aspect or the fourth aspect.
  • the electronic device since the electronic device includes the secondary battery of any one embodiment of the third aspect or the fourth aspect, the electronic device has the beneficial effects of the third aspect or the fourth aspect.
  • the electronic device of the present application is not particularly limited, and it can be any electronic device known in the prior art.
  • the electronic device can include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.
  • the cycle performance is evaluated by the capacity retention rate of the laminated battery.
  • the laminated battery after formation is placed in a constant temperature environment of 25°C, charged to 4.5V at a constant current of 0.6C, and then charged to a cut-off current of 0.05C at a constant voltage. After being fully charged and left for 3 minutes, it is discharged to 3.0V at 0.5C, and the discharge capacity is recorded as D 0 .
  • the cycle test is carried out with a 0.6C charge/0.5C discharge process, and the cycle is repeated for 500 times.
  • the discharge capacity after the 500th cycle is recorded as D 1 .
  • the capacity retention rate (%) of the laminated battery after 500 cycles at room temperature (25°C) D 1 /D 0 ⁇ 100%.
  • the laminated battery was placed in a constant temperature environment at 25°C, charged to 4.5V at a constant current of 0.6C, and then charged to a cut-off current of 0.05C at a constant voltage.
  • the initial thickness L 1 of the battery was measured.
  • the battery was then stored at 85°C for 24 hours to measure the thickness L 2 of the battery.
  • the formed laminated battery was placed in a constant temperature environment of 25°C, charged to 4.5V at a constant current of 0.6C, and then charged to a cut-off current of 0.05C at a constant voltage. After being fully charged and left for 3 minutes, it was discharged to 3.0V at 0.5C, and the discharge capacity was recorded as D 0 .
  • the cycle test was carried out with a 0.6C charge/0.5C discharge process. After 500 cycles, the battery cell was disassembled and photographed to observe the lithium deposition of the active material layer of the top and bottom single-sided positive electrode sheet of the laminated battery and the negative electrode sheet on the other side of the isolation membrane.
  • Lithium cobalt oxide, carbon nanotubes, conductive carbon black (Super P), and polyvinylidene fluoride in a mass ratio of 97.4:0.6:0.5:1.5 are mixed in NMP to obtain a positive electrode active slurry, wherein the solid content of the positive electrode active slurry is 75wt%; the positive electrode active slurry is coated on one side of an aluminum foil with a thickness of 9 ⁇ m, and the aluminum foil is dried at 95°C to obtain a positive electrode active material layer with a thickness of 60 ⁇ m, and the single-sided coated positive electrode sheet and the polypropylene film are passed between the upper roller and the lower roller, and the upper roller and the lower roller are in direct contact with the polypropylene film and the single-sided coated positive electrode sheet for rolling, and after rolling, they are rolled onto the sheet winding roller, and after cutting and slitting, they are dried under vacuum conditions at 85°C for 4h to obtain a single-sided positive electrode sheet.
  • the thickness of the polypropylene film is 1 ⁇ m, The pore diameter was 5 ⁇ m, the porosity was 50%, and the ratio S 1 /S 2 of the area S 1 of the polypropylene film to the area S 2 of the positive electrode active material layer was 1.06.
  • Lithium cobalt oxide, carbon nanotubes, conductive carbon black (Super P) and polyvinylidene fluoride in a mass ratio of 97.4:0.6:0.5:1.5 are mixed in NMP to obtain a positive electrode active slurry, wherein the solid content of the positive electrode active slurry is 75wt%; the positive electrode active slurry is coated on both sides of an aluminum foil, and the aluminum foil is dried at 95°C, and after cold pressing, cutting and slitting, it is dried under vacuum conditions at 85°C for 4 hours to obtain a double-sided positive electrode sheet.
  • Artificial graphite negative electrode active material, conductive agent Super P, thickener sodium carboxymethyl cellulose (CMC), and binder styrene butadiene rubber (SBR) in a mass ratio of 96.4:1.5:0.5:1.6 are mixed in deionized water to obtain a negative electrode active slurry, wherein the solid content of the negative electrode active slurry is 54wt%; the negative electrode active slurry is coated on both sides of a copper foil, and the copper foil is dried at 85°C, and then after cold pressing, cutting, and slitting, it is dried under vacuum conditions at 80°C for 12 hours to obtain a double-sided negative electrode sheet.
  • isolation film A 7 ⁇ m thick polyethylene (PE) isolation film substrate was coated with a 3 ⁇ m ceramic coating.
  • PE polyethylene
  • Preparation of laminated batteries The double-sided positive electrode sheets, double-sided negative electrode sheets and isolation films that have been cut after cold pressing are stacked in a Z shape in sequence, and finally finished with single-sided positive electrode sheets as the top and bottom layers. After laser cutting of the isolation film and ear transfer welding, the electrode assembly is placed in an aluminum-plastic film packaging shell, placed in a vacuum oven at 80°C and dried for 12 hours to remove moisture, and the prepared electrolyte is injected. After vacuum packaging, standing, formation, capacity, shaping and other processes, a laminated battery is obtained.
  • the obtained laminated battery was subjected to cycle performance test, thickness deviation rate test and lithium plating test, and the results are shown in Table 1.
  • the preparation process is substantially the same as that of Example 1, except that some parameters are different. The specific differences are shown in Table 1.
  • the obtained laminated battery was subjected to cycle performance test, thickness deviation rate test and lithium plating test, and the results are shown in Table 1.
  • Lithium cobalt oxide, carbon nanotubes, conductive carbon black (Super P), and polyvinylidene fluoride in a mass ratio of 97.4:0.6:0.5:1.5 were mixed in NMP to obtain a positive electrode active slurry, wherein the solid content of the positive electrode active slurry was 75wt%;
  • the slurry was coated on one side of an 8 ⁇ m thick aluminum foil, and the aluminum foil was dried at 95°C to obtain a 50 ⁇ m thick positive electrode active material layer.
  • the single-sided positive electrode sheet obtained after cold pressing was severely bent and curled, resulting in the inability to proceed normally in subsequent processes.
  • Lithium cobalt oxide, carbon nanotubes, conductive carbon black (Super P) and polyvinylidene fluoride in a mass ratio of 97.4:0.6:0.5:1.5 are mixed in NMP to obtain a positive electrode active slurry, wherein the solid content of the positive electrode active slurry is 75wt%; the positive electrode active slurry is coated on one side of an aluminum foil with a thickness of 8 ⁇ m, and the aluminum foil is dried at 95°C to obtain a positive electrode active material layer with a thickness of 50 ⁇ m, and the single-sided coated electrode is cold-pressed, sprayed with NMP, dried, cut and slit, and then dried under vacuum conditions at 85°C for 4h to obtain a single-sided positive electrode sheet.
  • the obtained laminated battery was subjected to cycle performance test, thickness deviation rate test and lithium plating test, and the results are shown in Table 1.
  • the thickness deviation rate, lithium precipitation and capacity retention rate of the laminated battery obtained in each embodiment are better than those of the comparative examples, indicating that the use of the single-sided positive electrode sheet provided in this application can not only improve production efficiency, but also effectively improve the electrical performance of the battery.
  • the single-sided positive electrode sheet was not further processed, and severe bending and curling occurred, resulting in the inability to proceed smoothly in subsequent processes.
  • the single-sided positive electrode sheet was processed using a conventional NMP spraying process. Although it can effectively improve the problems of bending and curling, additional processes such as spraying and drying are added, resulting in reduced costs and production efficiency.
  • NMP will cause the binder content on the surface of the active material layer to decrease, resulting in reduced adhesion between the single-sided positive electrode sheet and the isolation membrane, resulting in reduced electrical performance of the battery.
  • d 2 /d 1 has a certain influence on the electrical properties of the battery.
  • the battery has better electrical properties.
  • the thickness of the active material layer and the thickness of the first porous polymer layer can be appropriately selected on this basis.
  • the pore size and porosity of the first porous polymer membrane have a certain influence on the electrical properties of the battery.
  • the battery has good electrical properties.
  • the pore size of the first porous polymer layer is 3 ⁇ m to 7 ⁇ m and the porosity is 40% to 60%, the battery has better electrical properties.
  • Example 3 By comparing Example 3 and Examples 25 to 27, it can be seen that the thickness of the aluminum foil also has a certain influence on the electrical properties of the battery, which is reflected in that the greater the thickness, the better the electrical performance of the battery. However, considering the energy density, when the thickness of the aluminum foil is 8 ⁇ m to 10 ⁇ m, the energy density and electrical performance of the battery are better.
  • Example 3 By comparing Example 3 with Examples 28 to 30, it can be seen that the type of the first porous polymer membrane has little effect on the electrical performance of the battery, and the batteries obtained using commonly used porous polymer membranes all have good electrical performance.

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Abstract

一种电极组件、制备单面极片的方法、二次电池和电子设备，该电极组件，包括：多个第一极片，所述多个第一极片包括至少一个单面第一极片，所述单面第一极片包括集流体和活性材料层，所述活性材料层设置在所述集流体的一侧，和设置在所述活性材料层的与所述集流体相反一侧上的第一多孔聚合物层。通过在电极组件中单面第一极片的活性材料层表面结合多孔聚合物层，以改善单面极片弯曲、打卷的问题，由此保证单面第一极片生产的顺利进行，提高该电极组件的生产效率。

Description

电极组件、制备单面极片的方法、二次电池和电子设备
本申请要求于2023年7月6日提交中国专利局、申请号为202310823879.9、发明名称为“电极组件、制备单面极片的方法、二次电池和电子设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池技术领域，具体涉及一种电极组件、制备单面极片的方法、二次电池和电子设备。
背景技术
以锂离子电池为代表的二次电池由于具备高能量密度，长循环寿命，高安全性，快速充电能力等特性而被广泛应用于数码电子产品，储能，无人机，电动工具，电动车等产品上。相较于卷绕电池，叠片电池能够分利用电池空间，具有更高的能量密度。但是在叠片电池中，极片需要冷压、裁切后进行堆叠，其中单面极片(仅集流体的一侧涂布有活性材料层)冷压后，会出现弯曲、打卷的问题，导致后续工艺无法顺利进行。因此，需要改善上述问题。
发明内容
本申请提供了一种电极组件、制备单面极片的方法、二次电池和电子设备，旨在通过在单面极片的活性材料层表面结合多孔聚合物层，以改善单面极片弯曲、打卷的问题。
第一方面，本申请提供了一种电极组件，包括：多个第一极片，所述多个第一极片包括至少一个单面第一极片，所述单面第一极片包括集流体和活性材料层，所述活性材料层设置在所述集流体的一侧，所述单面第一极片还包括设置在所述活性材料层的与所述集流体相反一侧上的第一多孔聚合物层；和多个第二极片，所述第二极片与所述第一极片极性相反；和隔离膜，所述隔离膜包括第二多孔聚合物层；其中，所述第一极片和所述第二极片交替层叠设置，所述隔离膜设置于所述第一极片和所述第二极片之间。
根据本申请，电极组件中多个第一极片中包括至少一个单面第一极片，在该单面第一极片包括设置在集流体一侧的活性材料层，通过在活性材料层的与集流体相反一侧上设置第一多孔聚合物层，第一多孔聚合物层束缚活性材料层的延展，控制活性材料层中内应力的释放，从而改善单面第一极片弯曲、打卷的问题，由此保证单面第一极片生产的顺利进行，提高该电极组件的生产效率。
在一些实施方式中，所述第一多孔聚合物层的厚度d1与所述活性材料层的厚度d2满 足：20≤d2/d1≤50。在一些实施方式中，所述第一多孔聚合物层的厚度d1与所述活性材料层的厚度d2满足：25≤d2/d1≤40。
在一些实施方式中，所述第一多孔聚合物层的面积S1与所述活性材料层的面积S2满足：1.05≤S1/S2≤1.1。在一些实施方式中，所述第一多孔聚合物层的面积S1与所述活性材料层的面积S2满足：1.05≤S1/S2≤1.09。
在一些实施方式中，所述第一多孔聚合物层包括聚乙烯膜、聚丙烯膜、聚乙烯/聚丙烯双层膜、聚丙烯/聚乙烯/聚丙烯三层膜中的至少一种。
在一些实施方式中，所述第一多孔聚合物层的孔径为1μm至10μm，孔隙率为30％至70％。在一些实施方式中，所述第一多孔聚合物层的孔径为3μm至7μm，孔隙率为40％至60％。
在一些实施方式中，所述电极组件的最上层和最下层设置为所述单面第一极片，所述多个第一极片还包括双面第一极片，所述双面第一极片层叠设置在所述电极组件的中间层。
在一些实施方式中，所述第一极片为负极极片，所述第二极片为正极极片。
在一些实施方式中，所述第一极片为正极极片，所述第二极片为负极极片。
在一些实施方式中，所述单面第一极片至少满足以下条件中的一者：
1)所述集流体厚度为8μm至10μm；
2)所述活性材料层的厚度为50μm至80μm。
在一些实施方式中，所述隔离膜具有连续折弯结构。
第二方面，本申请提供了一种制备单面极片的方法，包括以下步骤：
S10：提供在集流体一面设置有活性材料层的极片；
S20：将第一多孔聚合物层结合在所述活性材料层的与所述集流体相反一侧上，以得到所述单面极片。
在一些实施方式中，所述步骤S20具体包括：
将第一多孔聚合物层通过冷压的方式与所述活性材料层结合，以得到所述单面极片。
第三方面，本申请提供了一种二次电池，包括：电解液，和根据第一方面任一实施方式所述的电极组件。
第四方面，本申请提供了一种二次电池，包括：隔离膜、电解液，和根据第二方面任一实施方式所述的方法制备得到的单面极片。
第五方面，一种电子设备，包括：根据第三方面或第四方面任一实施方式所述的二次 电池。
附图说明
此处的附图被并入说明书中并构成本说明书的一部分，示出了符合本申请的实施例，并与说明书一起用于解释本申请的原理。
图1为单面极片出现弯曲、打卷的示意图。
图2为本申请一实施例的电极组件中单面第一极片的结构示意图。
图3为本申请一实施例中制备单面极片的示意图。
其中，1-集流体，2-活性材料层，3-第一多孔聚合物层。
具体实施方式
本说明书中各实施例或实施方案采用递进的方案描述，每个实施例重点说明的都是与其他实施例的不同之处。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示意性实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合实施方式或示例描述的具体特征、结构、材料或者特点包含于本申请的至少一个实施方式或示例中。在本说明书中，对上述术语的示意性表述不一定指的是相同的实施方式或示例。而且，描述的具体特征、结构、材料或者特点可以在任何的一个或多个实施方式或示例中以合适的方案结合。
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本申请的描述中，“多个”的含义是至少两个，例如两个，三个等，除非另有明确具体的限定。
本申请中，电池可以包括锂离子二次电池、锂离子一次电池、锂硫电池、钠锂离子、钠离子电池或镁离子电池等，本申请实施例对此并不限定。电池可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。
在本申请的上下文中，除特殊说明外，单面极片指仅在集流体一侧设置有活性材料层的极片，相应的双面极片指同时在集流体两侧设置有活性材料层的极片。
如上文背景技术所述，在叠片电池中，极片需要冷压、裁切后进行堆叠，单面极片经过冷压后容易出现弯曲、打卷的现象，其具体示意图如图1，由于活性材料层2与集流体1的延展率不同，随着活性材料层2中内应力的释放，会导致活性材料层2向集流体1一面发生弯曲、打卷的现象，导致后续极片的裁切工艺无法顺利进行，进而影响电池的生产 效率，降低产能，也会降低包括。
针对于上述问题，相关技术中有对冷压后单面极片的活性材料层表面喷涂相应的溶剂(如N-甲基吡咯烷酮，NMP)，由于溶剂可以部分溶解活性材料层中的粘结剂，由此可以通过降低活性材料层粘结强度的方式，释放活性材料层中的内应力，进而改善单面极片冷压后弯曲、打卷的问题。但是该方法的问题在于，对冷压后单面极片的活性材料层表面喷涂溶剂后，还需要进一步对其高温干燥，一方面，喷涂溶剂和高温干燥过程增加了生产工艺步骤，导致生产成本增加，另一方面，喷涂溶剂和高温干燥处理后，活性材料层表面的粘结剂含量会显著降低，粗糙度变大，导致在后续的热压过程中，单面极片的活性材料层与隔离膜之间的粘结力降低，进而与隔离膜另一侧的活性材料层之间的距离变大，导致电池充放电过程中离子传输路径变长，长时间循环可能存在析锂以及异常膨胀等问题，电池的可靠性降低。
另外，其他相关技术中有对冷压后单面极片进行多次高温热压，通过使活性材料层中粘结剂软化，从而释放活性材料层中的内应力，进而改善单面极片冷压后弯曲、打卷的问题。但是该方法的问题在于，一方面多次高温热压需要大量能耗，导致成本增加，另一方面，热压容易出现沾辊的问题，同样会降低产能，成本增加。
有鉴于此，本申请提供了一种电极组件、制备单面极片的方法、二次电池和电子设备，使用本申请提供的电极组件中包括单面第一极片，通过在单面第一极片中活性材料层的与集流体相反一侧上设置第一多孔聚合物层，以改善单面极片发生弯曲、打卷的问题。以下对本申请的实施方式进行详细说明。
电极组件
第一方面，本申请提供了一种电极组件，包括：多个第一极片，多个第一极片包括至少一个单面第一极片，单面第一极片包括集流体和活性材料层，活性材料层设置在集流体的一侧，和设置在活性材料层的与集流体相反一侧上的第一多孔聚合物层；和多个第二极片，第二极片与第一极片极性相反；和隔离膜，隔离膜包括第二多孔聚合物层；其中，第一极片和第二极片交替层叠设置，隔离膜设置于第一极片和第二极片之间。
根据本申请，电极组件中包括多个第一极片、多个第二极片和隔离膜，其中，第一极片和所述第二极片交替层叠设置，隔离膜设置于第一极片和第二极片之间。多个第一极片包括至少一个单面第一极片，单面第一极片中仅集流体的一侧设置有活性材料层，通过在单面第一极片上活性材料层的与集流体相反一侧上设置第一多孔聚合物层。可以理解的是， 单面极片经过冷压后，由于活性材料层与集流体的延展率差别较大，由此随着活性材料层中内应力的释放，单面极片会出现弯曲、打卷的现象，出现该现象的原因主要在于，活性材料层具有一定的厚度，在粘结力的作用下，延展率较小的集流体会束缚活性材料层靠近集流体一侧的延展，而活性材料层的与集流体相反一侧不受束缚，由此随着应力的释放出现弯曲、打卷。而本申请的单面第一极片中，通过在活性材料层的与集流体相反一侧上设置第一多孔聚合物层后，由于第一多孔聚合物层的延展率相较于活性材料层更小，从而第一多孔聚合物层会束缚活性材料层与集流体相反一侧的延展，因此在第一多孔聚合物层和集流体的共同作用下，可以有效改善单面第一极片发生弯曲、打卷的问题，有利于提高电极组件的生产效率。另外需要说明的是，由于第一多孔聚合物层的多孔结构，在发挥上述效果的同时，对离子传输的影响不大，并不会使电池的电性能出现显著降低。
作为一个示例的，单面第一极片的结构示意图如图2所示，在集流体1的一侧结合有活性材料层2，在活性材料层的表面结合有第一多孔聚合物层3。需要说明的是，该单面第一极片仅仅是示例性的，本申请中单面第一极片还可以包括其他功能膜层，例如，在一些实施方式中，在集流体1与活性材料层2之间还可以设置有导电涂层(例如由粘接剂和导电剂组成)。
在一些实施方式中，第一多孔聚合物层的厚度d1与活性材料层的厚度d2满足：20≤d2/d1≤50。
在上述一些实施方式中，进一步优化了第一多孔聚合物层的厚度d1与活性材料层的厚度d2满足的关系，可以理解的是，第一多孔聚合物层相对厚度越大，对活性材料层的与集流体相反一侧的束缚作用越大，而同时也会导致能量密度以及电性能降低。由此，在第一多孔聚合物层的厚度d1与活性材料层的厚度d2满足：20≤d2/d1≤50的情况下，电极组件中单面第一极片的形状更稳定，进一步提高电极组件的生产效率，另外，此时包含该电极组件的电池的电性能更好。例如，d2/d1可以为25，27，29，30，32，34，36，38，40，42，44，46，48，50，或上述任意数值所组成的范围内，优选的，25≤d2/d1≤40。
在一些实施方式中，第一多孔聚合物层的面积S1与活性材料层的面积S2满足：1.05≤S1/S2≤1.1。
在上述一些实施方式中，进一步优化的第一多孔聚合物层的面积S1与活性材料层的面积S2的关系，通过控制第一多孔聚合物层的面积适当高于活性材料层的面积，可以更有效束缚活性材料层与集流体相反一侧的延展，提高单面第一极片形状的稳定性，进一步提高 电极组件的生产效率；另外，在电池循环过程中，即使第一多孔聚合物层出现收缩，依然能够保证单面第一极片的形状的稳定，提高二次电池的电性能。例如，S1/S2可以为1.05，1.06，1.07，1.08，1.09，1.1，或上述任意数值所组成的范围内，优选的，1.05≤S1/S2≤1.09。
在一些实施方式中，第一多孔聚合物层包括聚乙烯膜、聚丙烯膜、聚乙烯/聚丙烯双层膜、聚丙烯/聚乙烯/聚丙烯三层膜中的至少一种。
在上述一些实施方式中，具体列举了几种第一多孔聚合物层的具体材料，本领域技术人员可以根据实际需要进行选择其中一种或几种。另外可以理解的是，上述聚合物膜只是示例性的，一般而言，第一多孔聚合物层可以包括延展率小于活性材料层，且具有多孔结构的聚合物膜即可，本领域技术人员可以根据实际需要选择现有技术中任意满足上述要求的多孔聚合物膜作为第一多孔聚合物层。
在一些实施方式中，第一多孔聚合物层的孔径为1μm至10μm，孔隙率为30％至70％。
在上述一些实施方式中，进一步限定了第一多孔聚合物层的孔径和孔隙率，由于第一多孔聚合物层设置在活性材料层的与集流体相反一侧，在电池的充放电过程中离子需要穿过第一多孔聚合物层进入活性材料层，因此第一多孔聚合物层的孔径和孔隙率对包含该电极组件的电池的电性能具有一定影响。在第一多孔聚合物层的孔径为1μm至10μm，孔隙率为30％至70％的情况下，包含该电极组件的电池的电性能更好。例如，第一多孔聚合物层的孔径可以为1μm，2μm，3μm，4μm，5μm，6μm，7μm，8μm，9μm，10μm，或上述任意数值所组成的范围内；孔隙率可以为30％，35％，40％，45％，50％，55％，60％，65％，70％，或上述任意数值所组成的范围内。优选的，第一多孔聚合物层的孔径可以为3μm至7μm，孔隙率可以为40％至60％。
在一些实施方式中，电极组件的最上层和最下层设置为单面第一极片，多个第一极片还包括双面第一极片，双面第一极片层叠设置在电极组件的中间层。
在上述一些实施方式中，为了提高包含该电极组件的电池的能量密度，多个第一极片中还包括双面第一极片，且该双面第一极片层叠设置在电极组件的中间层。这是由于双面第一极片可以在活性材料层一定的条件下，降低集流体的层数，因此可以提高电池的能量密度；另外，电极组件的最上层和最下层设置为单面第一极片，这是由于如果双面第一极片设置在最上层或最下层，总会有一侧的活性材料层无法参与充放电循环，会增加成本且降低电池能量密度。由此，通过上述设置的电极组件，可有效提高电池的能量密度。
作为一个示例的，多个第二极片可以均为双面第二极片，此时得到的电池具有更高的 能量密度。
可以理解的是，本申请中第一极片和第二极片的极性可以不做进一步限定，即无论单面第一极片为负极极片还是为正极极片，均可以实现上文中单面第一极片的有益效果。
在一些实施方式中，第一极片为负极极片，第二极片为正极极片。
在上述一些实施方式中，分别对第一极片和第二极片的极性进行限定，在电极组件的最上层和最下层分别为单面第一极片的情况下，此时第一极片为负极极片，虽然相较于第一极片为正极极片时的能量密度有所降低，但是相对而言，电池的可靠性更高，可以适用于不同的使用环境。
在一些实施方式中，第一极片为正极极片，第二极片为负极极片。
在上述一些实施例中，同样分别对第一极片和第二极片的极性进行限定，可以理解的是，在电极组件的最上层和最下层分别为单面第一极片的情况下，可以更加有效提高电池的能量密度。
在一些实施方式中，单面第一极片至少满足以下条件中的一者：
1)集流体厚度为8μm至10μm；
2)活性材料层的厚度为50μm至80μm。
在上述一些实施方式中，在单面第一极片为正极极片的情况下，进一步限定了集流体厚度以及活性材料层厚度，过厚的集流体会降低电池的能量密度，而过薄的集流体的强度较低，在集流体厚度为8μm至10μm的情况下，电极组件中单面第一极片的稳定性更好，电极组件的生产效率更高，且包含该电极组件的电池具有较好的能量密度。过厚的活性材料层的延展性更大，可能降低第一单面极片的稳定性，过薄的活性材料层不利于能量密度的提高，在活性材料层的厚度为50μm至80μm的情况下，能够较好兼顾第一单面极片的稳定性以及包含该电极组件的电池的能量密度，另外可以理解的是，活性材料层厚度增加时，可以适当增加第一多孔聚合物层的厚度，来提高第一单面极片的稳定性，而由于第一多孔聚合物层的厚度过高显然也会影响离子传输，因此活性材料层的厚度不宜过高。
例如，集流体厚度可以为8μm，8.5μm，9μm，9.5μm，10μm，或上述任意数值所组成的范围内；活性材料层的厚度可以为50μm，52μm，55μm，58μm，60μm，65μm，70μm，72μm，75μm，78μm，80μm，或上述任意数值所组成的范围内。
在一些实施方式中，隔离膜具有连续折弯结构。
在上述一些实施方式中，具体限定了隔离膜可以具有连续折弯结构，更具体的，隔离 膜包括沿层叠方向设置的多片平直段和连接相邻两片平直段的折弯段，第一极片和第二极片之间由隔离膜的平直段彼此隔离的方式依次层叠设置。作为一个示例的，电极组件包括一个隔离膜，隔离膜具有连续折弯结构，包括沿层叠方向设置的多片平直段和连接相邻两片平直段的折弯段，第一极片和第二极片之间由隔离膜的平直段彼此隔离，并交替层叠设置。
在一些实施方式中，电极组件包括多个隔离膜，隔离膜可以具有平直结构，第一极片和第二极片之间由隔离膜彼此隔离，并交替层叠设置。
本申请中对隔离膜中第二多孔聚合物层不做限定，第二多孔聚合物层的材质可以选择聚乙烯、聚丙烯、聚偏氟乙烯中的一种或几种，但是不仅限于这些。第二多孔聚合物层可以是单层薄膜，也可以是多层复合薄膜。隔离膜为多层复合薄膜时，各层的材料相同或不同。在一些实施方式中，隔离膜上还可以设置陶瓷涂层、金属氧化物涂层。
本申请对集流体不做限定，可以使用金属箔材、多孔金属板或复合集流体。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。作为一个示例，集流体为铝箔。
本申请中单面第一极片中活性材料层中材料、过程和制备方法可包括任何现有技术中公知的技术。例如，活性材料层包括活性材料、导电剂、粘结剂。活性材料、导电剂、粘结剂可以是本领域通常使用的，且对具体类型没有具体限定。
例如，活性材料可以为正极活性材料，正极活性材料可以使用包括锂过渡金属氧化物、橄榄石结构的含锂磷酸盐及其各自的改性化合物中的一种或几种。上述各正极活性材料的改性化合物可以是对正极活性材料进行掺杂改性、表面包覆改性、或掺杂同时表面包覆改性。作为示例，锂过渡金属氧化物可以包括锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其改性化合物中的一种或几种。作为示例，橄榄石结构的含锂磷酸盐可以包括磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料及其改性化合物中的一种或几种。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
活性材料也可以为负极活性材料，可以使用包括碳质材料、可与锂合金化的金属化合物、可以掺杂和不掺杂锂的金属氧化物以及包括金属化合物和碳质材料的复合物中一种或几种。作为示例，碳质材料可以包括人造石墨、天然石墨、石墨化碳纤维和无定形碳中一种或几种；可与锂合金化的金属化合物可以包括硅(Si)、铝(Al)、锡(Sn)、铅(Pb)、锌(Zn)、铋(Bi)、铟(In)、镁(Mg)、镓(Ga)、镉(Cd)、Si合金、Sn合金或Al合金中一种或几种；可以掺杂和不掺杂锂的金属氧化物可以包括SiOv(0<v<2)、SnO2、钒氧化物和锂钒氧化物中一种或几种；包括金属化合物和碳质材料的复合物可以包括Si-C复合物和/或Sn-C复合物。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
例如，粘结剂可以使用包括聚偏二氟乙烯-六氟丙烯共聚物、聚乙烯醇、聚丙烯腈、淀粉、羟丙基纤维素、再生纤维素、聚乙烯吡咯烷酮、四氟乙烯、聚乙烯、聚丙烯、乙烯-丙烯-二烯聚合物(EPDM)、磺化的EPDM、羧甲基纤维素、丁苯橡胶、氟橡胶、或它们的各种共聚物中一种或几种。这些粘结剂可以仅单独使用一种，也可以将两种以上组合使用。
例如，导电剂可以使用包括石墨烯、网状石墨纤维、碳纳米管、科琴黑、石墨纤维或纳米颗粒导电碳中的一种或几种。
本申请中的电极组件可以按照本领域常规方法制备。例如，在一些实施方式中，将多个第一极片、多个第二极片和一个隔离膜依次进行Z字形堆叠以得到电极组件。在一些实施方式中，将多个第一极片、多个第二极片和多个隔离膜依次堆叠以得到电极组件。
单面极片
第二方面，本申请提供了一种制备单面极片的方法，包括以下步骤：
S10：提供在集流体一面设置有活性材料层的极片；
S20：将第一多孔聚合物层结合在活性材料层的与集流体相反一侧上，以得到单面极片。
根据本申请，在集流体一面设置有活性材料层的极片中活性材料层上结合第一多孔聚合物层，得到的单面极片不易发生弯曲、打卷的问题，从而保证单面极片生产的顺利进行。
本申请中单面极片可以是正极极片，也可以是负极极片。且第一多孔聚合物层、集流体以及活性材料层可以参照第一方面任一实施方式进行选择，在此不再进行赘述。
本申请中在集流体一面设置有活性材料层的极片可以按照本领域常规方法制备。例如，将活性材料、导电剂和粘结剂分散于溶剂中得到活性浆料，将活性浆料涂覆在集流体一面上，经烘干得到活性材料层，即得到在集流体一面设置有活性材料层的极片。
溶剂可以是水、二甲基甲酰胺(DMF)、二乙基甲酰胺、二甲基乙酰胺(DMAc)、N-甲基吡咯烷酮(NMP)、甲醇、乙醇、1-丙醇、2-丙醇(异丙醇)、1-丁醇(正丁醇)、2-甲基-1-丙醇(异丁醇)、2-丁醇(仲丁醇)、1-甲基-2-丙醇(叔丁醇)、戊醇、己醇、庚醇或辛醇；二醇，诸如乙二醇、二乙二醇、三乙二醇、丙二醇、1,3-丙二醇、1,3-丁二醇、1,5-戊二醇、己二醇、甘油、三羟甲基丙烷、季戊四醇、山梨糖醇、乙二醇单甲醚、二乙二醇单甲醚、三乙二醇单甲醚、四乙二醇单甲醚、乙二醇单乙醚、二乙二醇单乙醚、三乙二醇单乙醚、四乙二醇单乙醚、乙二醇单丁醚、二乙二醇单丁醚、三乙二醇单丁醚、四乙二醇单丁醚、丙酮、甲基乙基酮、甲基丙基酮、环戊酮、乙酸乙酯、γ-丁内酯和ε-丙内酯中一种或几种。这些分散介质可以仅单独使用一种，也可以将两种以上组合使用。
本申请并不排除，集流体和活性材料层之间含有其他附加功能层。例如，在一些实施方式中，在集流体一面设置有活性材料层的极片还包括夹在集流体和活性材料层之间、设置于集流体一面的导电涂层。
在一些实施方式中，步骤S20具体包括：
将第一多孔聚合物层通过冷压的方式与活性材料层结合，以得到单面极片。
在上述一些实施方式中，具体限定了第一多孔聚合物层与活性材料层的结合方式，由于活性材料层中含有粘结剂，通过冷压的方式可以使第一多孔聚合物层与活性材料层稳定粘结，更好的粘结力可以更好束缚活性材料层的延伸，提高单面极片的稳定性。
另外，由于一般为了得到具有合适压实密度的活性材料层，冷压是极片制备过程中常用的工艺，由此可以将第一多孔聚合物层结合在活性材料层这一过程与冷压同时进行，一方面相较于一般极片生产无需添加额外的工序，提高生产效率，另一方面，由于单面极片的弯曲、打卷现象是由于冷压导致的，因此同时进行可以显著提高单面极片的稳定性，保证工艺的顺利进行。
作为一个示例的，制备单面极片的方法的示意图如图3所示，集流体一面设置有活性材料层的极片(图中的单面涂布极片)和第一多孔聚合物膜同时放卷，经过上轧辊和下轧辊之间进行轧制，极片中活性材料层与第一多孔聚合物膜通过冷压结合，最后收卷得到单面极片。
在一些实施方式中，将单面极片经过裁剪后可作为第一方面任一实施方式中单面第一极片。
二次电池
第三方面，本申请提供了一种二次电池，包括：电解液，和根据第一方面任一实施方式的电极组件。
根据本申请，该二次电池包括第一方面任一实施方式的电极组件，由此具有第一方面任一实施方式中有益效果。
【电解液】
电解液在第一极片和第二极片之间起到传导活性离子的作用。可用于本申请二次的电解液可以为现有技术已知的电解液。
在一些实施方式中，所述电解液可包括有机溶剂、电解质盐和可选的添加剂，有机溶剂、锂盐和添加剂的种类均不受到具体的限制，可根据需求进行选择。
在一些实施方式中，二次电池为锂离子电池，所述电解质盐可以包括锂盐。作为示例，所述锂盐包括但不限于LiPF6(六氟磷酸锂)、LiBF6(四氟硼酸锂)、LiClO4(高氯酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO2F2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的至少一种。上述锂盐可以单独使用一种，也可以同时使用两种或两种以上。
在一些实施方式中，二次电池为钠离子电池，所述电解质盐可以包括钠盐。作为示例，钠盐可选自NaPF6、NaClO4、NaBCl4、NaSO3CF3及Na(CH3)C6H4SO3中的至少一种。
在一些实施方式中，作为示例，所述有机溶剂包括但不限于碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、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)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的至少一种。上述有机溶剂可以单独使用一种，也可以同时使用两种或两种以上。可选地，上述有机溶剂同时使用两种或两种以上。
在一些实施方式中，所述添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
作为示例，所述添加剂包括但不限于氟代碳酸乙烯酯(FEC)、碳酸亚乙烯酯(VC)、 乙烯基碳酸乙烯酯(VEC)、硫酸乙烯酯(DTD)、硫酸丙烯酯、亚硫酸乙烯酯(ES)、1,3-丙磺酸内酯(PS)、1,3-丙烯磺酸内酯(PST)、磺酸酯环状季铵盐、丁二酸酐、丁二腈(SN)、己二腈(AND)、三(三甲基硅烷)磷酸酯(TMSP)、三(三甲基硅烷)硼酸酯(TMSB)中的至少一种。
电解液可以按照本领域常规的方法制备。例如，可以将有机溶剂、电解质盐、可选的添加剂混合均匀，得到电解液。各物料的添加顺序并没有特别的限制，例如，将电解质盐、可选的添加剂加入到有机溶剂中混合均匀，得到电解液；或者，先将电解质盐加入有机溶剂中，然后再将可选的添加剂加入有机溶剂中混合均匀，得到电解液。
第四方面，本申请提供了一种二次电池，包括：隔离膜、电解液，和根据第二方面任一实施方式的方法制备得到的单面极片。
根据本申请，该二次电池包括第二方面任一实施方式的单面极片，由此具有第二方面任一实施方式中有益效果。
在一些实施方式中，根据第二方面任一实施方式的方法制备得到的单面极片作为正极极片。上文已对单面极片作为正极极片的实施方式进行详细说明，在此不再重复。
在一些实施方式中，根据第二方面任一实施方式的方法制备得到的单面极片作为负极极片。上文已对单面极片作为负极极片的实施方式进行详细说明，在此不再重复。
【电解液】
上文已对电解液的实施方式进行详细说明，在此不再重复。
电子设备
第五方面，一种电子设备，包括：根据第三方面或第四方面任一实施方式的二次电池。
根据本申请，由于电子设备包括第三方面或第四方面任一实施例的二次电池，因此该电子设备具有第三方面或第四方面的有益效果。
本申请的电子设备没有特别限定，其可以是用于现有技术中已知的任何电子设备。在一些实施例中，电子设备可以包括但不限于，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。
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
测试部分：
1.循环性能测试
通过叠片电池的容量保持率对循环性能进行评价。将化成后的叠片电池置于25℃恒温环境条件中，以0.6C恒流充电到4.5V，然后再恒压充电至截止电流0.05C，满充搁置3min后再以0.5C放电到3.0V，记录放电容量为D0。以0.6C充电/0.5C放电流程进行循环测试，循环500圈，记录第500次循环后的放电容量为D1，叠片电池在常温(25℃)循环500圈后的容量保持率(％)＝D1/D0×100％。
2.厚度偏移率测试
将叠片电池置于25℃恒温环境条件中，以0.6C恒流充电到4.5V，然后再恒压充电至截止电流0.05C，测量电芯初始厚度L1，随后将其置于85℃下存储24H后测得电芯厚度L2，
电芯厚度偏移率(％)＝(L2-L1)/L1×100％。
3.析锂测试
将化成后的叠片电池置于25℃恒温环境条件中，以0.6C恒流充电到4.5V，然后再恒压充电至截止电流0.05C，满充搁置3min后再以0.5C放电到3.0V，记录放电容量为D0。以0.6C充电/0.5C放电流程进行循环测试，循环500圈后对电芯拆解拍照，观察叠片电池最顶层和最底层单面正极极片活性物质层与隔离膜相对另一侧负极极片析锂情况。
实施例1
单面正极极片的制备：
将质量比为97.4:0.6:0.5:1.5的钴酸锂、碳纳米管、导电炭黑(Super P)、聚偏二氟乙烯混合在NMP中得到正极活性浆料，其中，正极活性浆料的固含量为75wt％；将正极活性浆料涂覆在厚度为9μm铝箔的一面上，将铝箔在95℃烘干得到厚度为60μm的正极活性材料层，将单面涂布正极极片和聚丙烯膜从上轧辊和下轧辊之间穿过，上轧辊及下轧辊和聚丙烯膜及单面涂布正极极片直接接触进行碾压，碾压后收卷到极片收卷辊上，经过裁片、分切后，在85℃的真空条件下干燥4h，得到的单面正极极片。其中，聚丙烯膜的厚度为1μm、 孔径为5μm、孔隙率为50％，聚丙烯膜的面积S1正极活性材料层的面积S2之比S1/S2为1.06。
双面正极极片的制备：
将质量比为97.4:0.6:0.5:1.5的钴酸锂、碳纳米管、导电炭黑(Super P)、聚偏二氟乙烯混合在NMP中得到正极活性浆料，其中，正极活性浆料的固含量为75wt％；将正极活性浆料涂覆在铝箔的两面上，将铝箔在95℃烘干，经过冷压、裁片、分切后，在85℃的真空条件下干燥4h，得到的双面正极极片。
双面负极极片的制备：
将质量比为96.4:1.5:0.5:1.6的人造石墨负极活性材料、导电剂Super P、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)混合在去离子水中得到负极活性浆料，其中负极活性浆料的固含量为54wt％；将负极活性浆料涂覆在铜箔的两面上，将铜箔在85℃下烘干，然后经过冷压、裁片、分切后，在80℃的真空条件下干燥12h，得到双面负极极片。
电解液的制备：在充有干燥氩气气氛的手套箱中，将有机溶剂碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸乙烯酯(EC)以质量比1:1:1混合，然后向上述有机溶剂中加入六氟磷酸锂(LiPF6)锂盐溶解并混合均匀，得到浓度为1.5mol/L六氟磷酸锂电解液。
隔离膜的制备：选用7μm厚的聚乙烯(PE)隔离膜基材涂覆3μm陶瓷涂层。
叠片电池的制备：将冷压后裁切好的双面正极极片、双面负极极片和隔离膜依次进行Z字形堆叠，最后以单面正极极片作为最顶层和最底层收尾，激光裁切隔离膜、极耳转接焊后将电极组件装入铝塑膜包装壳中，放置在80℃真空烘箱中干燥12小时脱去水分，注入配好的电解液，经过真空封装、静置、化成、容量、整形等工序得到叠片电池。
将得到的叠片电池进行循环性能测试、厚度偏移率测试和析锂测试，结果如表1。
实施例2至实施例30
制备过程与实施例1大致相同，区别仅在于部分参数不同，具体区别如表1所示。
将得到的叠片电池进行循环性能测试、厚度偏移率测试和析锂测试，结果如表1。
对比例1
区别仅在于单面正极极片的制备方法不同，具体为：
单面正极极片的制备：
将质量比为97.4:0.6:0.5:1.5的钴酸锂、碳纳米管、导电炭黑(Super P)、聚偏二氟乙烯混合在NMP中得到正极活性浆料，其中，正极活性浆料的固含量为75wt％；将正极活 性浆料涂覆在厚度为8μm铝箔的一面上，将铝箔在95℃烘干得到厚度为50μm的正极活性材料层，进行冷压后得到的单面正极极片出现严重的弯曲、打卷，导致后续工序无法正常进行。
对比例2
区别仅在于单面正极极片的制备方法不同，具体为：
单面正极极片的制备：
将质量比为97.4:0.6:0.5:1.5的钴酸锂、碳纳米管、导电炭黑(Super P)、聚偏二氟乙烯混合在NMP中得到正极活性浆料，其中，正极活性浆料的固含量为75wt％；将正极活性浆料涂覆在厚度为8μm铝箔的一面上，将铝箔在95℃烘干得到厚度为50μm的正极活性材料层，将单面涂布的极片进行冷压后，使用NMP进行喷涂处理，再经过干燥处理经过裁片、分切后，在85℃的真空条件下干燥4h，得到的单面正极极片。
将得到的叠片电池进行循环性能测试、厚度偏移率测试和析锂测试，结果如表1。

根据表1，各实施例得到的叠片电池的厚度偏移率、析锂情况以及循环500圈容量保持率均优于各对比例，说明使用本申请提供的单面正极极片，不仅能够提高生产效率，还能有效改善电池的电性能。对比例1中单面正极极片不经过进一步处理，发生严重弯曲、打卷，导致后续工序无法顺利进行。对比例2中单面正极极片使用常规喷涂NMP的工艺进行处理，虽然能够有效改善弯曲、打卷的问题，但是额外增加了喷涂、烘干等工艺，导致成本和生产效率降低，另外由于NMP会导致活性材料层表面的粘结剂含量降低，导致单面正极极片和隔离膜之间粘接性降低，导致电池的电性能降低。
进一步的，对比实施例1至实施例5、实施例21至实施例24可知，d2/d1对电池的电性能具有一定影响，在20≤d2/d1≤50的情况下，电池具有较好的电性能，优选的，在25≤d2/d1≤40的情况下，电池的电性能更好。由此，活性材料层的厚度和第一多孔聚合物层的厚度可以在此基础上进行适当选择。
对比实施例3和实施例6至实施例12可知，S1/S2对电池的电性能具有一定影响，在1.05≤S1/S2≤1.1的情况下，电池具有较好的电性能，优选的，在1.05≤S1/S2≤1.09的情况下，电池的电性能更好。
对比实施例3和实施例13至实施例20可知，第一多孔聚合物膜的孔径以及孔隙率对电池的电性能具有一定影响，在第一多孔聚合物层的孔径为1μm至10μm，孔隙率为30％至70％的情况下，电池具有较好的电性能，优选的，在第一多孔聚合物层的孔径为3μm至7μm，孔隙率为40％至60％的情况下，电池的电性能更好。
对比实施例3和实施例25至实施例27可知，铝箔的厚度对电池的电性能也有一定影响，体现在厚度越大，电池的电性能越好，但是处于对能量密度的考虑，在铝箔的厚度为8μm至10μm的情况下，电池的能量密度和电性能较好。
对比实施例3和实施例28至实施例30可知，第一多孔聚合物膜的种类对电池的电性能影响不大，使用常用的多孔聚合物膜得到的电池均具有较好的电性能。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (15)

  1. 一种电极组件，其特征在于，包括：
    多个第一极片，所述多个第一极片包括至少一个单面第一极片，所述单面第一极片包括集流体和活性材料层，所述活性材料层设置在所述集流体的一侧，所述单面第一极片还包括设置在所述活性材料层的与所述集流体相反一侧上的第一多孔聚合物层；
    多个第二极片，所述第二极片与所述第一极片极性相反；和
    隔离膜，所述隔离膜包括第二多孔聚合物层；
    其中，所述第一极片和所述第二极片交替层叠设置，所述隔离膜设置于所述第一极片和所述第二极片之间。
  2. 根据权利要求1所述的电极组件，其特征在于，所述第一多孔聚合物层的厚度d1与所述活性材料层的厚度d2满足：20≤d2/d1≤50。
  3. 根据权利要求1所述的电极组件，其特征在于，所述第一多孔聚合物层的面积S1与所述活性材料层的面积S2满足：1.05≤S1/S2≤1.1。
  4. 根据权利要求1所述的电极组件，其特征在于，至少满足以下条件中的一者：
    1)所述第一多孔聚合物层的厚度d1与所述活性材料层的厚度d2，满足25≤d2/d1≤40；
    2)所述第一多孔聚合物层的面积S1与所述活性材料层的面积S2满足：1.05≤S1/S2≤1.09。
  5. 根据权利要求1所述的电极组件，其特征在于，所述第一多孔聚合物层包括聚乙烯膜、聚丙烯膜、聚乙烯/聚丙烯双层膜、聚丙烯/聚乙烯/聚丙烯三层膜中的至少一种。
  6. 根据权利要求1所述的电极组件，其特征在于，所述第一多孔聚合物层的孔径为1μm至10μm，孔隙率为30％至70％。
  7. 根据权利要求1所述的电极组件，其特征在于，所述第一多孔聚合物层的孔径为3μm至7μm，孔隙率为40％至60％。
  8. 根据权利要求1至7任一项所述的电极组件，其特征在于，所述电极组件的最上层和最下层设置为所述单面第一极片，所述多个第一极片还包括双面第一极片，所述双面第一极片层叠设置在所述电极组件的中间层。
  9. 根据权利要求8所述的电极组件，其特征在于，所述单面第一极片至少满足以下条件中的一者：
    1)所述集流体厚度为8μm至10μm；
    2)所述活性材料层的厚度为50μm至80μm。
  10. 根据权利要求1至7任一项所述的电极组件，其特征在于，所述隔离膜具有连续折弯结构。
  11. 一种制备单面极片的方法，其特征在于，包括以下步骤：
    S10：提供在集流体一面设置有活性材料层的极片；
    S20：将第一多孔聚合物层结合在所述活性材料层的与所述集流体相反一侧上，以得到所述单面极片。
  12. 根据权利要求11所述的方法，其特征在于，所述步骤S20具体包括：
    将第一多孔聚合物层通过冷压的方式与所述活性材料层结合，以得到所述单面极片。
  13. 一种二次电池，其特征在于，包括：电解液，和根据权利要求1至10任一项所述的电极组件。
  14. 一种二次电池，其特征在于，包括：隔离膜、电解液，和根据权利要求11或12所述方法制备得到的单面极片。
  15. 一种电子设备，其特征在于，包括：根据权利要求13或14所述的二次电池。
PCT/CN2024/098628 2023-07-06 2024-06-12 电极组件、制备单面极片的方法、二次电池和电子设备 Ceased WO2025007715A1 (zh)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090042100A1 (en) * 2007-08-10 2009-02-12 Sanyo Electric Co., Ltd. Non-aqueous electrolyte battery and negative electrode used therein
JP2013109866A (ja) * 2011-11-17 2013-06-06 Toyota Motor Corp リチウム二次電池
CN103855360A (zh) * 2014-02-27 2014-06-11 宁德新能源科技有限公司 锂离子电池及其负极极片及制备方法
CN106471646A (zh) * 2014-10-31 2017-03-01 株式会社Lg 化学 二次电池用电极、其制造方法、包含其的二次电池及线缆型二次电池
CN110635162A (zh) * 2019-09-23 2019-12-31 深圳市泽塔电源系统有限公司 电化学储能装置及制造方法
CN112259796A (zh) * 2020-10-21 2021-01-22 珠海冠宇动力电池有限公司 一种叠片电芯和锂离子电池
CN113097568A (zh) * 2021-03-30 2021-07-09 宁德新能源科技有限公司 电化学装置及应用其的电子装置

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011014238A (ja) * 2009-06-30 2011-01-20 Panasonic Corp 非水電解質二次電池用電極群及び非水電解質二次電池
KR102580239B1 (ko) * 2020-03-09 2023-09-19 삼성에스디아이 주식회사 복합 세퍼레이터 제조 방법, 복합세퍼레이터 및 이를 채용한 리튬 전지
CN116130651A (zh) * 2021-11-12 2023-05-16 宁德时代新能源科技股份有限公司 极片、锂离子电池、电池模块、电池包及用电装置
CN115842094B (zh) * 2022-05-19 2024-03-22 宁德时代新能源科技股份有限公司 负极极片及其制备方法、二次电池、电池模块、电池包及用电装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090042100A1 (en) * 2007-08-10 2009-02-12 Sanyo Electric Co., Ltd. Non-aqueous electrolyte battery and negative electrode used therein
JP2013109866A (ja) * 2011-11-17 2013-06-06 Toyota Motor Corp リチウム二次電池
CN103855360A (zh) * 2014-02-27 2014-06-11 宁德新能源科技有限公司 锂离子电池及其负极极片及制备方法
CN106471646A (zh) * 2014-10-31 2017-03-01 株式会社Lg 化学 二次电池用电极、其制造方法、包含其的二次电池及线缆型二次电池
CN110635162A (zh) * 2019-09-23 2019-12-31 深圳市泽塔电源系统有限公司 电化学储能装置及制造方法
CN112259796A (zh) * 2020-10-21 2021-01-22 珠海冠宇动力电池有限公司 一种叠片电芯和锂离子电池
CN113097568A (zh) * 2021-03-30 2021-07-09 宁德新能源科技有限公司 电化学装置及应用其的电子装置

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