WO2023035762A1 - 一种可吸附气体的金属复合膜及其制备方法、袋装电池 - Google Patents

一种可吸附气体的金属复合膜及其制备方法、袋装电池 Download PDF

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WO2023035762A1
WO2023035762A1 PCT/CN2022/104942 CN2022104942W WO2023035762A1 WO 2023035762 A1 WO2023035762 A1 WO 2023035762A1 CN 2022104942 W CN2022104942 W CN 2022104942W WO 2023035762 A1 WO2023035762 A1 WO 2023035762A1
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activated carbon
adsorption layer
battery
metal composite
gas
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PCT/CN2022/104942
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English (en)
French (fr)
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庄志
郭宏伟
鲍晋珍
袁凯杰
王迎利
虞少波
吴惠康
何方波
马六甲
李恒
程跃
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珠海恩捷新材料科技有限公司
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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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • 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
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/116—Primary casings; Jackets or wrappings characterised by the material
    • H01M50/124—Primary casings; Jackets or wrappings characterised by the material having a layered structure
    • H01M50/1243—Primary casings; Jackets or wrappings characterised by the material having a layered structure characterised by the internal coating on the casing
    • 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 invention relates to the technical field of aluminum-plastic films, in particular to a metal composite film capable of absorbing gas, a preparation method thereof, and a bagged battery.
  • lithium-ion secondary batteries with high energy density have been continuously developed and applied in various fields.
  • the electrolyte is easy to decompose and generate gas.
  • bubbles will form on the contact interface between the electrolyte and the electrode and on the diaphragm.
  • Lithium-ion secondary batteries mainly produce gases such as N 2 , C 2 H 6 , C 2 H 4 , CO 2 , CO, H 2 , etc., with the most content being C 2 H 4 and CO 2 gases, and C 2 H 4 gases are mainly
  • the source is the decomposition of the EC solvent in the electrolyte on the surface of the negative electrode to form an SEI film and the reformation after the SEI film is destroyed; CO2 comes from the oxidative decomposition of alkyl lithium carbonate and the solvent.
  • the existing bagged battery technology does not have any simple and economical solution to the problem of battery gas production.
  • a safety valve is installed on the aluminum-plastic film of the bagged battery, and the safety valve and the aluminum-plastic film are connected by hot-melt adhesive. Since the ultimate pressure of the bagged battery is different from that of the safety valve valve ball/valve plate, when the gas in the bag reaches the pressure value of the safety valve, the safety valve will open to discharge the internal gas to the outside to prevent the lithium battery from being damaged due to excessive internal pressure. The purpose of causing battery safety problems.
  • the present invention starts with the aluminum-plastic film of the soft-pack battery, sprays or brushes a layer of activated carbon material with a high specific surface area and well-developed diameter distribution on the inner side of the aluminum-plastic film corresponding to the bare cell, and absorbs the battery.
  • Excessive C 2 H 4 and CO 2 gases in the chemical system so as to solve the excessive gas production of the battery inside the battery, to control the internal pressure of the battery, and effectively avoid the safety problems caused by the excessive internal pressure of the battery.
  • the attenuation is suppressed, the electrochemical performance of the lithium battery is improved, and the service life of the lithium battery is prolonged.
  • the object of the present invention is to provide a metal composite film capable of adsorbing gas, which is composed of an aluminum-plastic film, an activated carbon adsorption layer and a selective permeable film; On the inner side of the liquid (hereinafter referred to as the inner side of the aluminum-plastic film); the activated carbon adsorption layer is covered with a selective permeable membrane whose area is larger than that of the activated carbon adsorption layer.
  • the activated carbon adsorption layer is formed by coating and drying activated carbon slurry; the activated carbon slurry includes activated carbon material, adhesive, and solvent.
  • the solid content of the activated carbon slurry is 55-65%, wherein the solid content is 92-95 parts by weight of activated carbon material and 5-8 parts of adhesive.
  • the activated carbon material has a three-dimensional hierarchical porous structure with micropores, mesopores and macropores; its particle size distribution is D10: 1.40-2.90 ⁇ m, D50: 4.20-6.40 ⁇ m, D90: 8.20-14.10 ⁇ m.
  • the particle size distribution of the activated carbon material is D10: 1.47-2.82 ⁇ m, D50: 4.23-6.33 ⁇ m, and D90: 8.21-14.05 ⁇ m.
  • the specific surface area of the activated carbon material is 1600m 2 /g-2100m 2 /g.
  • the specific surface area of the activated carbon material is 1689m 2 /g-2100m 2 /g.
  • the adhesive is at least one of polytetrafluoroethylene, vinylidene fluoride, styrene-butadiene rubber, polyvinyl alcohol, polyethylene, and polypropylene.
  • the material of the selectively permeable membrane is selected from one of polytetrafluoroethylene, vinylidene fluoride, and nylon 6.
  • the purpose of the present invention is to also provide a method for preparing a gas-adsorbable metal composite film, comprising the following steps:
  • the solid content of the activated carbon slurry is 55-65%, wherein the solid content is 92-95 parts by weight of activated carbon material, 5-8 Parts of adhesive;
  • the prepared activated carbon slurry is evenly coated on the inner side of the aluminum-plastic film that contacts the electrolyte when the battery is packaged, and an activated carbon adsorption layer is formed after drying;
  • the activated carbon adsorption layer with a selective permeable membrane with an area larger than that of the activated carbon adsorption layer.
  • the selective permeable membrane is fixed on the aluminum-plastic film in a thermoplastic form to contact the electrolyte when packaging the battery. on the inner side.
  • the purpose of the present invention is also to provide a pouch battery, comprising any one of the metal composite films that can absorb gas.
  • the present invention has the following beneficial effects:
  • the present invention absorbs excessive C 2 H 4 in the electrochemical system by coating a layer of activated carbon slurry with a high specific surface area and developed pore size distribution on the inner side of the aluminum-plastic film that contacts the electrolyte when it is used for packaging batteries And CO 2 gas, so as to solve the excessive gas production of the battery inside the battery cell, so as to control the internal pressure of the battery, and effectively avoid the safety problems caused by the excessive internal pressure of the battery;
  • the present invention can also improve the electrochemical performance of the battery, suppress attenuation, prolong the service life of the battery, and be more resistant to use in high temperature environments.
  • Fig. 1 is the cross-sectional structure schematic diagram of the metal composite film of the present invention that can absorb gas
  • Fig. 2 is the structural representation of the metal composite membrane of the adsorbed gas after the flushing process of the present invention
  • Fig. 3 is the scanning electron micrograph of active carbon material of the present invention.
  • Fig. 4 is the transmission electron microscope figure of active carbon material of the present invention.
  • Fig. 5 is the specific surface area adsorption-desorption curve figure of active carbon material of the present invention.
  • Fig. 6 is the pore size distribution curve figure of active carbon material of the present invention.
  • Fig. 7 is the pore size range-pore specific surface area figure of active carbon material of the present invention.
  • Fig. 8 is a graph of battery cycle life curves of Example 3 of the present invention and Comparative Examples 7, 8, and 9 running 1000 laps at 55°C;
  • the aluminum-plastic film is used for the inside of the electrolyte when packaging the battery
  • the specific embodiment of the present invention provides a metal composite film capable of adsorbing gas, which is composed of an aluminum-plastic film, an activated carbon adsorption layer 2 and a selective permeable film 3; the activated carbon adsorption layer 2 is arranged on the aluminum-plastic film for packaging
  • the inner side 1 of the battery contacts the electrolyte; the activated carbon adsorption layer 2 is covered with a selective permeable membrane 3 whose area is larger than that of the activated carbon adsorption layer.
  • the aluminum-plastic film may include an outer substrate resin layer, an intermediate metal layer, an inner adhesive layer, and an inner heat-welding layer; it may also include an anti-corrosion layer, an outer adhesive layer, and a colored layer.
  • the inner heat-welding layer the inner side 1 of the aluminum-plastic film in the present invention that contacts the electrolyte when it is used for packaging batteries refers to the side where the inner heat-welding layer of the aluminum-plastic film contacts the electrolyte.
  • the thickness of the activated carbon adsorption layer 2 is 40-70 ⁇ m.
  • the activated carbon adsorption layer 2 is formed by coating and drying activated carbon slurry; the activated carbon slurry includes activated carbon material, adhesive, and solvent.
  • the solid content of the activated carbon slurry is 55-65%, wherein the solid content is 92-95 parts by weight of activated carbon material and 5-8 parts of adhesive.
  • the activated carbon material has a three-dimensional hierarchical porous structure with micropores, mesopores and macropores; its particle size distribution is D10: 1.40-2.90 ⁇ m, D50: 4.20-6.40 ⁇ m, D90: 8.20-14.10 ⁇ m. Further preferably, the particle size distribution of the activated carbon material is D10: 1.47-2.82 ⁇ m, D50: 4.23-6.33 ⁇ m, and D90: 8.21-14.05 ⁇ m.
  • the specific surface area of the activated carbon material is 1600m 2 /g-2100m 2 /g. More preferably, the specific surface area of the activated carbon material is 1689 m 2 /g to 2100 m 2 /g.
  • this kind of developed hierarchical porous structure realizes the three-dimensional interpenetration of mesopores on the macropores and micropores on the mesopores.
  • the surface area increases the active sites for gas adsorption, which is beneficial to the physical adsorption of gas molecules; and during the pore-forming process, the pore-forming agent will form a large number of oxygen-containing functional groups on the surface of the activated carbon material, which helps the activated carbon material
  • this kind of pore size structure and pore size distribution will not cause a large expansion of the adsorption material after adsorbing gas, and avoid the extrusion of the adsorption layer to the electrode; this kind of particle size distribution is beneficial to the activated carbon slurry.
  • the coating makes the activated carbon surface density of the adsorption layer the highest.
  • the activated carbon material of the adsorption layer 2 has a hierarchical porous structure of micropores, mesopores and macropores, and is a good gas adsorption material.
  • the preparation method of the activated carbon material add the activated carbon precursor to the aqueous solution of the activator, stir at 50°C, the precursor and the activator are cross-linked to form a gel, and then put it in an oven at 80°C for 2 hours.
  • the dried product is placed in a tube furnace for carbonization and activation in an inert gas atmosphere. After the activation process is completed, the temperature of the tube furnace is lowered to room temperature, the activated product is cleaned, and then dried to obtain the activated carbon material with a high specific surface area and a three-dimensional interpenetrating hierarchical porous structure required for the adsorption layer.
  • the activated carbon precursor is one of starch, flour or biomass fiber;
  • the inert gas is nitrogen, one of argon;
  • the activator is KOH, NaOH, ZnCl 2.
  • At least one of NaCl, the ratio of the precursor to the activator is 1-2;
  • the carbonization and activation process the heating rate is 5°C/min, from room temperature to 400°C, and stay at 400°C, stay The time is 1 ⁇ 2h; then the temperature is raised from 400°C to 800°C at a heating rate of 5°C/min, and stay at 800°C for 1h for activation.
  • the activated product is cleaned until the solution is neutral, and then dried to obtain an activated carbon material.
  • the adhesive is at least one of polytetrafluoroethylene, vinylidene fluoride, styrene-butadiene rubber, polyvinyl alcohol, polyethylene, and polypropylene.
  • the solvent is not limited, for example, it may be acetonitrile, ethyl acetate, ethylene carbonate, cyclohexanone, propylene carbonate and the like.
  • the material of the selectively permeable membrane 3 is selected from one of polytetrafluoroethylene, vinylidene fluoride, and nylon 6.
  • the selective permeable membrane 3 is fixed on the inner side of the aluminum-plastic membrane 1 through thermoplastic, so as to prevent the activated carbon adsorption layer 2 from contacting the electrolyte.
  • the four sides of the selectively permeable membrane 3 should not exceed the top-side sealing boundary, because the different softening points of polymer materials may affect the sealing performance of the aluminum-plastic membrane.
  • the selective permeable membrane 3 is gas-permeable and impermeable to the electrolyte, therefore, it can prevent the electrolyte in the battery from being adsorbed by the activated carbon adsorption layer 2, resulting in poor electrochemical performance of the battery and the gas adsorption performance of the activated carbon adsorption layer 2.
  • the specific embodiment of the present invention also provides a method for preparing a gas-adsorbable metal composite film, comprising the following steps:
  • the solid content of the activated carbon slurry is 55-65%, wherein the solid content is 92-95 parts by weight of activated carbon material, 5-8 Parts of adhesive;
  • the prepared activated carbon slurry is evenly coated on the inner side 1 of the aluminum-plastic film that contacts the electrolyte when the battery is packaged, and the activated carbon adsorption layer 2 is formed after drying;
  • the selective permeable membrane 3 is fixed on the aluminum-plastic film in a thermoplastic form for packaging batteries. When in contact with the electrolyte on the inner side 1.
  • the specific embodiment of the present invention also provides a pouch battery, including any one of the metal composite films that can absorb gas.
  • the process of preparing the bagged battery there is no limitation on the selection of materials such as the positive electrode, the negative electrode, the electrolyte, and the winding or stacking process, as long as the bagged battery can be prepared, for example, the positive electrode nickel cobalt manganese 523 ( NCM523), negative electrode graphite, and winding process to prepare pouched batteries.
  • the positive electrode nickel cobalt manganese 523 NCM523
  • negative electrode graphite negative electrode graphite
  • the position of the punching pit 4 should coincide with the position of the activated carbon adsorption layer 2 during the pit punching process, and the activated carbon adsorption layer 2 cannot overlap with the heat sealing area, otherwise the tightness of the top and side seals of the battery will be affected.
  • Battery gas volume test method liquid discharge method test, suspend the battery cell after gas production in the liquid, observe the rising volume of the liquid level, which is the gas production volume.
  • the thickness of the battery cell is tested by a flat plate thickness gauge.
  • the K value test is tested by a voltage detection device (such as a multimeter, a blue battery, and an electrochemical workstation)
  • a voltage detection device such as a multimeter, a blue battery, and an electrochemical workstation
  • the gas-adsorbable aluminum-plastic film pouch battery based on high specific surface area activated carbon material
  • the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film, and an adsorption layer 2 and a bare battery.
  • the selective permeable membrane 3 between the cells; the adsorption layer 2 is 40 ⁇ m, which is made of activated carbon slurry after coating, drying and rolling.
  • the solid content of the activated carbon slurry is 55%, the specific surface area of the activated carbon is 1689m 2 /g, the particle size distribution is D10: 1.47 ⁇ m, D50: 4.23 ⁇ m, D90: 8.21 ⁇ m, and the activated carbon material in the activated carbon slurry is 92 parts by weight;
  • the adhesive is polytetrafluoroethylene, 8 parts; the solvent is ethylene carbonate; the selective permeable membrane 3 is a polytetrafluoroethylene film.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned airless aluminum-plastic film packaging bag containing the adsorption layer 2 and the selective permeable membrane 3.
  • the size of the bare cell is 51*90*3.5mm.
  • the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film; the adsorption layer 2 is 40 ⁇ m, made from activated carbon slurry after coating, drying and rolling.
  • the solid content of the activated carbon slurry is 55%
  • the specific surface area of the activated carbon is 1689m 2 /g
  • the particle size distribution is D10: 1.47 ⁇ m, D50: 4.23 ⁇ m, D90: 8.21 ⁇ m
  • the activated carbon material in the activated carbon slurry is 92 parts by weight
  • the adhesive is polytetrafluoroethylene, 8 parts
  • the solvent is ethylene carbonate.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned air bag aluminum-plastic film packaging bag containing the adsorption layer 2, and the size of the bare cell is 51*90*3.5mm. After the prepared battery cells were formed by hot pressing at 45°C, no double-sealing operation was performed, and the changes in the thickness of the battery cell and the thickness of the battery cell before formation and the gas production inside the bagged battery were observed.
  • An aluminum-plastic film pouch battery based on an air-adsorbable gas-adsorbable non-selective permeable membrane 3 with a high specific surface area activated carbon material the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film ;
  • the adsorption layer 2 is 40 ⁇ m, which is made of activated carbon slurry after coating, drying and rolling.
  • the solid content of the activated carbon slurry is 55%, the specific surface area of the activated carbon is 1689m 2 /g, the particle size distribution is D10: 1.47 ⁇ m, D50: 4.23 ⁇ m, D90: 8.21 ⁇ m, and the activated carbon material in the activated carbon slurry is 92 parts by weight;
  • the adhesive is polytetrafluoroethylene, 8 parts; the solvent is propylene carbonate.
  • the battery is composed of a NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned airless aluminum-plastic film packaging bag containing the adsorption layer 2.
  • the size of the bare cell is 51*90*3.5mm.
  • the battery is composed of a NCM523 positive electrode graphite negative electrode wound bare cell and an aluminum-plastic film packaging bag with an air bag but no adsorption layer.
  • the size of the bare cell is 51*90*3.5mm.
  • Example 1 in terms of gas production and cell thickness, the data of Example 1 is the best compared with Comparative Examples 2, 3 and 4, and compared with the original thickness of the cell, the cell thickness of Example 1 is at There is no significant increase after the formation, indicating that the pouch battery containing the adsorption layer 2 and the permeable selective membrane 3 can ignore the existence of air pockets, and the gas generated during the formation stage can be fully absorbed by the adsorption layer 2 .
  • the gas-adsorbable aluminum-plastic film pouch battery based on high specific surface area activated carbon material
  • the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film, and an adsorption layer 2 and a bare battery.
  • the selective permeable membrane 3 between the cells; the adsorption layer 2 is 70 ⁇ m, which is made of activated carbon slurry after coating, drying and rolling.
  • the solid content of activated carbon slurry is 65%, the specific surface area of activated carbon is 2100m 2 /g, the particle size distribution is D10: 1.55 ⁇ m, D50: 4.84 ⁇ m, D90: 9.34 ⁇ m, 92 parts by weight of activated carbon material in the activated carbon slurry ;
  • the adhesive is tetrafluoroethylene, 5 parts;
  • the solvent is ethyl acetate;
  • the selective permeable membrane 3 is a nylon 6 membrane.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned airless aluminum-plastic film packaging bag containing the adsorption layer 2 and the selective permeable membrane 3.
  • the size of the bare cell is 51*90*3.5mm.
  • the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film; the adsorption layer 2 is 70 ⁇ m, made from activated carbon slurry after coating, drying and rolling.
  • the solid content of the activated carbon slurry is 65%
  • the specific surface area of the activated carbon is 2100m 2 /g
  • the particle size distribution is D10: 1.55 ⁇ m
  • the activated carbon material in the activated carbon slurry is 92 parts by weight
  • the adhesive is vinylidene, 5 parts
  • the solvent is ethylene carbonate.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned air bag aluminum-plastic film packaging bag containing the adsorption layer 2, and the size of the bare cell is 51*90*3.5mm. After the prepared battery was formed at 45°C, the two air bags were cut off, and then placed at a high temperature of 85°C at 100% SOC. The thickness of the battery cell before and after the high temperature storage was observed, the gas production inside the bagged battery, and the K value of the battery voltage drop.
  • An aluminum-plastic film pouch battery based on an air-adsorbable gas-adsorbable non-selective permeable membrane 3 with a high specific surface area activated carbon material the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film ;
  • the adsorption layer 2 is 70 ⁇ m, which is made by coating, drying and rolling the activated carbon slurry.
  • the solid content of the activated carbon slurry is 65%, the specific surface area of the activated carbon is 2100m 2 /g, the particle size distribution is D10: 1.55 ⁇ m, D50: 4.84 ⁇ m, D90: 9.34 ⁇ m, and the activated carbon material in the activated carbon slurry is 92 parts by weight;
  • the adhesive is tetrafluoroethylene, 5 parts; the solvent is propylene carbonate.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned airless aluminum-plastic film packaging bag containing the adsorption layer 2, and the size of the bare cell is 51*90*3.5mm. After the prepared battery was formed at 45°C, it was stored at a high temperature of 85°C under 100% SOC, and the thickness change of the battery cell before and after the high-temperature storage, the gas production inside the bagged battery, and the battery voltage drop K value were observed.
  • the battery is composed of a NCM523 positive electrode graphite negative electrode wound bare cell and an aluminum-plastic film packaging bag with an air bag but no adsorption layer 2.
  • the size of the bare cell is 51*90*3.5mm.
  • the battery was formed at 45°C and cut off the two air bags, and then placed at 85°C at 100% SOC for high-temperature storage. The internal gas production of the bagged battery, the change of cell thickness before and after high-temperature storage, and the battery voltage drop K value were observed.
  • the gas generated by the battery cell is mainly CO2 gas generated by solvent decomposition at high potential.
  • the pouched battery with activated carbon adsorption layer 2 has The thickness of the cell and the total amount of gas in the selective permeable membrane 3 are the best.
  • the activated carbon adsorption layer 2 does not fully act on the gas because part of the electrolyte is adsorbed by the activated carbon adsorption layer 2.
  • the electrolyte K value results show that the embodiment 2 with the selective permeable membrane 3 is the best.
  • Comparative Examples 4 and 5 without the selective permeable membrane 3 increased significantly. This is because the absence of the selective permeable membrane 3 caused the electrolyte to be adsorbed by the active material, resulting in the deterioration of the electrical performance of the battery and making the voltage drop increases. Comparative example 6 has the worst cell thickness and voltage drop due to excessive gas production.
  • the gas-adsorbable aluminum-plastic film pouch battery based on high specific surface area activated carbon material
  • the adsorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film, and an adsorption layer between the adsorption layer and the bare cell.
  • the selective permeation membrane 3 between the cores; the adsorption layer 2 is 70 ⁇ m, which is made of activated carbon slurry after coating, drying and rolling.
  • the solid content of the activated carbon slurry is 63%, the specific surface area of the activated carbon is 1830m 2 /g, the particle size distribution is D10: 2.82 ⁇ m, D50: 6.33 ⁇ m, D90: 14.05 ⁇ m, and the activated carbon material in the activated carbon slurry is 95 parts by weight;
  • the adhesive is polyvinyl alcohol, 5 parts; the solvent is cyclohexanone and propylene carbonate; the selective permeable membrane 3 is vinylidene fluoride membrane.
  • An aluminum-plastic film pouch battery with an air bag that can absorb gas based on a high specific surface area activated carbon material the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film; the adsorption layer 2 is 70 ⁇ m, made from activated carbon slurry after coating, drying and rolling.
  • the solid content of the activated carbon slurry is 63%, the specific surface area of the activated carbon is 1830m 2 /g, the particle size distribution is D10: 2.82 ⁇ m, D50: 6.33 ⁇ m, D90: 14.05 ⁇ m, and the activated carbon material in the activated carbon slurry is 95 parts by weight;
  • the adhesive is polyvinyl alcohol, 5 parts; the solvent is acetonitrile and ethyl acetate.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned air bag aluminum-plastic film packaging bag containing the adsorption layer 2, and the size of the bare cell is 51*90*3.5mm.
  • the prepared batteries were hot-pressed at 45°C and then cut off the two seals of the air bags. Then, a 55°C cycle (1000 cycles) experiment was performed to observe the thickness changes of the cells before and after cycling and the gas production inside the bagged batteries.
  • An aluminum-plastic film pouch battery based on an air-adsorbable gas-adsorbable non-selective permeable membrane 3 with a high specific surface area activated carbon material the absorbable aluminum-plastic film pouch battery includes an adsorption layer 2 coated on the aluminum-plastic film ;
  • the adsorption layer 2 is 70 ⁇ m, which is made by coating, drying and rolling the activated carbon slurry.
  • the solid content of the activated carbon slurry is 63%, the specific surface area of the activated carbon is 1830m 2 /g, the particle size distribution is D10: 2.82 ⁇ m, D50: 6.33 ⁇ m, D90: 14.05 ⁇ m, and the activated carbon material in the activated carbon slurry is 95 parts by weight;
  • the adhesive is polyvinyl alcohol, 5 parts; the solvent is propylene carbonate.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and the above-mentioned airless aluminum-plastic film packaging bag containing the adsorption layer 2, and the size of the bare cell is 51*90*3.5mm.
  • a 55°C cycle (1000 cycles) experiment was performed to observe the thickness change of the cells before and after cycling and the gas production inside the pouched batteries.
  • the battery is composed of NCM523 positive electrode graphite negative electrode wound bare cell and an aluminum-plastic film packaging bag without adsorption layer 2, and the size of the bare cell is 51*90*3.5mm. After the battery is formed, vacuumize the second seal and cut off the air bag to cycle at 55°C (1000 cycles), observe the thickness change of the cell before and after the cycle and the gas production inside the bagged battery.

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Abstract

一种可吸附气体的金属复合膜，其由铝塑膜、活性炭吸附层（2）及选择性透过膜（3）组成；活性炭吸附层（2）设置于铝塑膜用于包装电池时接触电解液的内侧（1）上；活性炭吸附层（2）上覆盖一层面积大于活性炭吸附层（2）的选择性透过膜（3）。通过在铝塑膜用于包装电池时接触电解液的内侧（1）上涂覆一层具有高比表面积且孔径分布发达的活性炭浆料，吸附电化学体系中的过多C2H4与CO2气体。

Description

一种可吸附气体的金属复合膜及其制备方法、袋装电池 技术领域
本发明涉及铝塑膜技术领域，具体涉及一种可吸附气体的金属复合膜及其制备方法、袋装电池。
背景技术
随着人们对新能源汽车以及各种3C数码产品需求的日益旺盛，高能量密度的锂离子二次电池被不断的开发并应用于各个领域。然而，锂离子二次电池在高温环境下存储、循环以及过充过放等异常使用条件下，电解液易分解产生气体，气体在电芯内部集聚会导致电芯内部内压升高，并带来一系列问题。首先，电解液与电极接触界面以及隔膜上会形成气泡，这些气泡会影响到锂离子的扩散与传输，造成电芯内阻增加，影响电芯电化学性能；其次，内部压力过高可能会导致电极变形，增加电芯内短路风险；高压气体还会使得电芯壳体变形，严重的还会导致着火或者爆炸。
锂离子二次电池主要产生为N 2，C 2H 6，C 2H 4，CO 2，CO，H 2等气体，含量最多的为C 2H 4与CO 2气体，C 2H 4气体主要来源为电解液中的EC溶剂在负极表面的分解形成SEI膜以及SEI膜破坏后的重整导致；CO 2则源自烷基碳酸锂及溶剂的氧化分解。
现有的袋装电池技术并没有什么即简单又经济的办法来解决电池产气的问题，通常是在袋装电池铝塑膜上安装安全阀，安全阀与铝 塑膜通过热熔胶相连。由于袋装电池与安全阀阀球/阀片所承受极限压力不同，当袋内气体达到安全阀压力值时，安全阀打开，将内部气体排出到外部，达到防止锂电池由于内部气压过大而造成电池安全性问题的目的。然而这种安全阀多半是由压紧弹簧与金属球或金属片以及阀壳构成，存在结构复杂且不易安装等问题；或是由不同形变量的弹性金属合金与阀壳构成，虽然结构上要优于压紧弹簧安全阀，但是金属合金制造成本高，同样也需要采用热熔胶与铝塑膜相连，存在着不易安装的问题。并且，安全阀一旦打开，内部环境与外部环境相连，不仅电池即判定失效，同时电池内部的烷类，醚类，烯烃类可燃性气体直接排出到环境，造成环境污染与安全隐患。
目前另外一种方法是从电池内部解决产气问题，在制作电极时添加MH合金类物质制成可吸附气体的电极，在电池运行中将产生的气体被电极中混合的合金材料吸附于晶格当中，起到抑制电池产气膨胀的目的。然而MH金属制造成本高，且只能吸附氢气，同时对工艺要求较高，存在大规模推广的困难。
发明内容
为了克服现有技术的不足，本发明从软包电池铝塑膜入手，在铝塑膜内侧对应裸电芯位置喷涂或刷涂一层孔具有高比表面积且径分布发达的活性炭材料，吸附电化学体系中的过多C 2H 4与CO 2气体，从而在电芯内部解决电池产气过多，以控制电池内部压力，有效避免电池内部压力过高而带来的安全性问题。同时，抑制衰减，提高锂电池的电化学性能，延长锂电池的使用寿命。
为达到上述目的，本发明的技术方案是这样实现的：
本发明目的在于提供一种可吸附气体的金属复合膜，由铝塑膜、活性炭吸附层及选择性透过膜组成；所述活性炭吸附层设置于所述铝塑膜用于包装电池时接触电解液的内侧(下面可简述为铝塑膜内侧)上；所述活性炭吸附层上覆盖一层面积大于活性炭吸附层的选择性透过膜。
进一步地，所述活性炭吸附层由活性炭浆料经涂覆、干燥后形成；所述活性炭浆料包括活性炭材料、胶粘剂、溶剂。
更进一步地，所述活性炭浆料固含量为55～65％，其中固体份按重量计为92～95份的活性炭材料，5～8份的胶粘剂。
具体地，所述活性炭材料具有微孔、介孔与大孔兼具的三维分级多孔结构；其粒径分布为D10:1.40～2.90μm，D50:4.20～6.40μm，D90:8.20～14.10μm。
优选的，所述活性炭材料粒径分布为D10:1.47～2.82μm，D50:4.23～6.33μm，D90:8.21～14.05μm。
具体地，所述活性炭材料的比表面积为1600m 2/g～2100m 2/g。
优选的，所述活性炭材料的比表面积为1689m 2/g～2100m 2/g。
具体地，所述胶粘剂为聚四氟乙烯、偏四氟乙烯、丁苯橡胶、聚乙烯醇、聚乙烯、聚丙烯中的至少一种。
进一步地，所述选择性透过膜的材料选自聚四氟乙烯，偏四氟乙烯，尼龙6中的一种。
本发明目的在于还提供一种可吸附气体金属复合膜的制备方法，包括以下步骤：
(1)活性炭浆料的制备：
将活性炭材料、胶粘剂和溶剂混合，搅拌均匀即得所述活性炭浆 料；所述活性炭浆料固含量为55～65％，其中固体份按重量计为92～95份的活性炭材料，5～8份的胶粘剂；
(2)活性炭吸附层的形成：
将制得的活性炭浆料均匀涂覆在所述铝塑膜用于包装电池时接触电解液的内侧上，经干燥后形成活性炭吸附层；
(3)可吸附气体金属复合膜的制备：
再在所述活性炭吸附层上覆盖一层面积大于活性炭吸附层的选择性透过膜，所述选择性透过膜是通过热塑形式固定在所述铝塑膜用于包装电池时接触电解液的内侧上。
本发明目的在于还提供一种袋装电池，包括上述任一种可吸附气体的金属复合膜。
与现有技术相比，本发明具有如下有益效果：
(1)本发明通过在铝塑膜用于包装电池时接触电解液的内侧上涂覆一层具有高比表面积且孔径分布发达的活性炭浆料，吸附电化学体系中的过多C 2H 4与CO 2气体，从而在电芯内部解决电池产气过多，以控制电池内部压力，有效避免电池内部压力过高而带来的安全性问题；
(2)发达的孔径分布使得吸附层在吸附气体后袋装电池体积膨胀较小，使其在电池化成时期就可以吸附大量的化成气体，省略了气袋，免去了电池二封的步骤，大大降低了铝塑膜的材料成本及人工成本，此外，电池体积膨胀较小将给电池电化学设计提供了大大的空间，这在特别追求高比能量、低成本的动力电池领域中将是巨大的进步；
(3)本发明还能提高电池的电化学性能，抑制衰减，延长电池的使用寿命，且更耐高温环境下使用。
附图说明
图1为本发明可吸附气体的金属复合膜的截面结构示意图；
图2为本发明冲坑工艺后的吸附气体的金属复合膜的结构示意图；
图3为本发明活性炭材料的扫描电镜图；
图4为本发明活性炭材料的透射电镜图；
图5为本发明活性炭材料的比表面积吸脱附曲线图；
图6为本发明活性炭材料的孔径分布曲线图；
图7为本发明活性炭材料的孔径范围-孔比表面积图；
图8为本发明实施例3与对比例7、8、9在55℃下跑1000圈的电池循环寿命曲线图；
元件标号说明
1、铝塑膜用于包装电池时接触电解液的内侧
2、活性炭吸附层
3、选择性透过膜
4、冲坑
具体实施方式
以下对本发明的具体实施方式结合附图进行详细说明。应当理解的是，此处所描述的具体实施方式仅用于说明和解释本发明，并不用于限制本发明。
本发明具体实施方式提供一种可吸附气体的金属复合膜，由铝塑膜、活性炭吸附层2及选择性透过膜3组成；所述活性炭吸附层2设置于所述铝塑膜用于包装电池时接触电解液的内侧1上；所述活性炭吸附层2上覆盖一层面积大于活性炭吸附层的选择性透过膜3。
这里，有关铝塑膜自身的结构不作任何限定，只要本领域技术人员可以制备出袋装电池的铝塑膜均可以。譬如该铝塑膜可以包括外基材树脂层、中间金属层、内胶粘剂层、内热熔接层；还可以包括防腐蚀层、外胶粘剂层、着色层。当定义为内热熔接层时，此时本发明所述铝塑膜用于包装电池时接触电解液的内侧1即指为铝塑膜内热熔接层接触电解液的该侧。
进一步地，所述活性炭吸附层2的厚度为40～70μm。
进一步地，所述活性炭吸附层2由活性炭浆料经涂覆、干燥后形成；所述活性炭浆料包括活性炭材料、胶粘剂、溶剂。
更进一步地，所述活性炭浆料固含量为55～65％，其中固体份按重量计为92～95份的活性炭材料，5～8份的胶粘剂。
优选所述活性炭材料具有微孔、介孔与大孔兼具的三维分级多孔结构；其粒径分布为D10:1.40～2.90μm，D50:4.20～6.40μm，D90:8.20～14.10μm。进一步优选活性炭材料粒径分布为D10:1.47～2.82μm，D50:4.23～6.33μm，D90:8.21～14.05μm。
优选所述活性炭材料的比表面积为1600m 2/g～2100m 2/g。进一步优选活性炭材料的比表面积为1689m 2/g～2100m 2/g。
这里，该种发达的分级多孔结构，实现了大孔上有介孔，介孔上有微孔的三维互穿，孔上造孔，孔中有孔的发达孔径分布，提高了活性材料的比表面积，增加了气体可吸附的活性位点，有利于对气体分子的物理吸附；并且在造孔过程中，造孔剂会在活性炭材料表面形成的大量的含氧官能团，这有助于活性炭材料对气体分子的化学吸附，该种孔径结构及孔径分布在吸附气体后不会引起吸附材料体积较大的膨胀，避免了吸附层对电极的挤压；该种粒径分布下有利于活性炭浆料的涂布，使得吸附层活性炭面密度最高。
如图3，从活性炭材料扫描电镜图可以看出，表面具有发达的孔径，主要显示为大孔；如图4，从透射电镜图可以看出，所制备活性炭是具有三维互穿结构，并且在5nm尺度上可以观察到大量的微孔存在；如图5～7所示，显示该种材料2nm以下微孔居多，其中0.5～1nm范围内的微孔最多。因此结合扫描电镜与透射电镜可以确定，吸附层2的活性炭材料具有微孔介孔大孔的分级多孔结构的活性炭材料，是良好的气体吸附材料。
这里，所述活性炭材料的制备方法：将活性炭前驱体加入到活化剂水溶液中，在50℃下搅拌，前驱体与活化剂交联呈凝胶状，随后放入80℃烘箱中烘干2h，将烘干后的产物置于管式炉中，在惰性气体氛围中，进行炭化与活化。活化过程结束后待管式炉温度降低为室温，将活化产物进行清洗，随后烘干得到吸附层所需的具有高比表面积三维互穿分级多孔结构的活性炭材料。
活上述性炭制备方法中，所述活性炭前驱体为淀粉、面粉或生物质纤维中的一种；所述惰性气体为氮气，氩气中的一种；所述活化剂为KOH，NaOH，ZnCl 2，NaCl中的至少一种，前驱体与活化剂比例为1～2；所述炭化与活化过程，升温速率为5℃/min，从室温升至400℃，并在400℃停留，停留时间为1～2h；随后从400℃以5℃/min升温速率升温至800℃，并在800℃下停留1h进行活化。待管式炉温度降至室温，对活化产物进行清洗至溶液呈中性，随后烘干得到活性炭材料。
具体地，所述胶粘剂为聚四氟乙烯、偏四氟乙烯、丁苯橡胶、聚乙烯醇、聚乙烯、聚丙烯中的至少一种。
具体地，所述溶剂不作限定，例如可以为乙腈，乙酸乙酯，碳酸乙烯酯，环己酮，碳酸丙烯酯等。
进一步地，所述选择性透过膜3的材料选自聚四氟乙烯，偏四氟乙烯，尼龙6中的一种。
更进一步地，所述选择性透过膜3是通过热塑形式固定在铝塑膜内侧1，防止活性炭吸附层2与电解液接触。
这里，选择性透过膜3四边不要超过顶侧封边界，因为高分子材料软化点不一样可能会影响铝塑膜的密封性。
这里，所述选择性透过膜3透气体不透电解液，因此，可以防止电池内电解液被活性炭吸附层2吸附，从而导致电池电化学性能以及活性炭吸附层2吸附气体性能不佳。
本发明具体实施方式还提供一种可吸附气体金属复合膜的制备方法，包括以下步骤：
(1)活性炭浆料的制备：
将活性炭材料、胶粘剂和溶剂混合，搅拌均匀即得所述活性炭浆料；所述活性炭浆料固含量为55～65％，其中固体份按重量计为92～95份的活性炭材料，5～8份的胶粘剂；
(2)活性炭吸附层2的形成：
将制得的活性炭浆料均匀涂覆在所述铝塑膜用于包装电池时接触电解液的内侧1上，经干燥后形成活性炭吸附层2；
(3)可吸附气体金属复合膜的制备：
再在所述活性炭吸附层2上覆盖一层面积大于活性炭吸附层2的选择性透过膜3，所述选择性透过膜3是通过热塑形式固定在所述铝塑膜用于包装电池时接触电解液的内侧1上。
本发明具体实施方式还提供一种袋装电池，包括上述任一种可吸附气体的金属复合膜。
这里，制备袋装电池的过程中，对正极、负极、电解液等材料 以及卷绕或叠片工艺的选择不作限定，只要能制备出袋装电池即可，譬如可以选择正极镍钴锰523(NCM523)、负极石墨、卷绕工艺来制备袋装电池。
这里，如图2，冲坑工艺时冲坑4位置应与活性炭吸附层2位置重合，活性炭吸附层2不能与热封区域重合，否则会影响电池顶侧封的严密性。
以下将通过实施例对本发明进行详细描述。
在以下实施例和对比例中，相关数据按照如下方法测定：
1、电池气体体积测试方法：排液法测试，将产气后电芯悬置于液体内，观察液面上升体积，即为产气体积。
2、通过气相色谱法来分析气体组分及占比。
3、电芯厚度采用平板测厚仪测试。
4、K值测试采用电压检测装置测试(如万用表，蓝电，电化学工作站均可)
5、活性炭材料比表面积与孔径分布采用麦克默瑞提克ASAP2020比表面积仪测试。
实施例1
基于高比表面积活性炭材料的可吸附气体的无气袋铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2，以及位于吸附层2与裸电芯之间的选择性透过膜3；所述吸附层2为40μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为55％，其中活性炭比表面积为1689m 2/g，粒径分布为D10：1.47μm，D50：4.23μm，D90：8.21μm，按重量计活性炭浆料中活性炭材料92份；所述胶粘剂为聚四氟乙烯，为8份；所述溶剂为碳酸乙烯酯；所述选择性透过膜3为聚四氟乙烯膜。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2及选择性透过膜3的无气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电芯经45℃热压化成后，观察电芯厚度与化成前电芯厚度的变化以及袋装电池内部产气量。
比较例1
基于高比表面积活性炭材料的可吸附气体的具有气袋的铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2；所述吸附层2为40μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为55％，其中活性炭比表面积为1689m 2/g，粒径分布为D10：1.47μm，D50：4.23μm，D90：8.21μm，按重量计活性炭浆料中活性炭材料92份；所述胶粘剂为聚四氟乙烯，为8份；所述溶剂为碳酸乙烯酯。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2的有气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电芯经45℃热压化成后，不进行二封操作，观察电芯厚度与化成前电芯厚度的变化以及袋装电池内部产气量。
比较例2
基于高比表面积活性炭材料的可吸附气体的无气袋无选择性透过膜3的铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2；所述吸附层2为40μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为55％，其中活性炭比表面积为1689m 2/g，粒径分布为D10：1.47μm，D50：4.23μm，D90：8.21μm，按重量计活性炭浆料中活性炭材料92份；所述胶粘剂为聚四氟乙烯，为8份；所述溶剂为碳酸丙烯酯。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸 附层2的无气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电芯经45℃热压化成后，观察电芯厚度与化成前电芯厚度的变化以及袋装电池内部产气量。
比较例3
所述电池由NCM523正极石墨负极的卷绕裸电芯与具有气袋但不含有吸附层2铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电芯经45℃热压化成后，观察电芯厚度与化成前电芯厚度的变化以及袋装电池内部产气量。
表1化成后产气量及电芯厚度变化
Figure PCTCN2022104942-appb-000001
Figure PCTCN2022104942-appb-000002
由表1可以看出，在产气与电芯厚度方面，实施例1的数据与比较例2，3与4相比最佳，同时与电芯原始厚度比较，实施例1的电芯厚度在经过化成后没有明显增加，说明含有吸附层2及选择性透过膜3的袋装电池可以忽略气袋的存在，在化成阶段产生的气体可以被吸附层2充分的吸收。
实施例2
基于高比表面积活性炭材料的可吸附气体的无气袋铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2，以及位于吸附层2与裸电芯之间的选择性透过膜3；所述吸附层2为70μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为65％，其中活性炭比表面积为2100m 2/g，粒径分布为D10：1.55μm，D50：4.84μm，D90：9.34μm，，按重量计活性炭浆料中活性炭材料92份；所述胶粘剂为偏四氟乙烯，为5份；所述溶剂为乙酸乙酯；所述选择性透过膜3为尼龙6膜。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2及选择性透过膜3的无气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电池经过45℃化成后在100％SOC下进行85℃高温搁置，观察高温搁置前后电芯厚度变化，袋装电池内部产气量以及电池电压降K值。
比较例4
基于高比表面积活性炭材料的可吸附气体的具有气袋的铝塑膜 袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2；所述吸附层2为70μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为65％，其中活性炭比表面积为2100m 2/g，粒径分布为D10：1.55μm，D50：4.84μm，D90：9.34μm，按重量计活性炭浆料中活性炭材料92份；所述胶粘剂为偏四氟乙烯，为5份；所述溶剂为碳酸乙烯酯。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2的有气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电池经过45℃化成后剪去气袋二封，后在100％SOC下进行85℃高温搁置，观察高温搁置前后电芯厚度变化，袋装电池内部产气量以及电池电压降K值。
比较例5
基于高比表面积活性炭材料的可吸附气体的无气袋无选择性透过膜3的铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2；所述吸附层2为70μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为65％，其中活性炭比表面积为2100m 2/g，粒径分布为D10：1.55μm，D50：4.84μm，D90：9.34μm，按重量计活性炭浆料中活性炭材料92份；所述胶粘剂为偏四氟乙烯，为5份；所述溶剂为碳酸丙烯酯。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2的无气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电池经过45℃化成后在100％SOC下进行85℃高温搁置，观察高温搁置前后电芯厚度变化，袋装电池内部产气量以及电池电压降K值。
比较例6
所述电池由NCM523正极石墨负极的卷绕裸电芯与具有气袋但不含有吸附层2的铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所述电池经45℃化成剪去气袋二封，后在100％SOC下进行85℃高温搁置，观察袋装电池内部产气量、高温搁置前后电芯厚度变化以及电池电压降K值。
表2 100％SOC下85℃高温搁置后产气量及电芯厚度变化
Figure PCTCN2022104942-appb-000003
Figure PCTCN2022104942-appb-000004
由表2可以看出，在高温存储过程中，电芯产生的气体主要为高电位下溶剂分解产生的CO 2气体，由上表可以看出，添加了活性炭吸附层2的袋装电池，具有选择性透过膜3的电芯厚度与气体总量表现最好。不含有选择性透过膜3的比较例4与5，由于部分电解液被活性炭吸附层2吸附，使得活性炭吸附层2未完全对气体产生作用。同时电解液K值结果显示具有选择性透过膜3的实施例2最好。无选择性透过膜3的比较例4与5的K值明显增大，这是由于选择性透过膜3的缺失使得电解液被活性材料吸附，导致了电池的电性能变差，使得电压降增加。比较例6由于产气过多的缘故，导致了其电芯厚度以及电压降最差。
实施例3
基于高比表面积活性炭材料的可吸附气体的无气袋铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2，以及位于吸附层与裸电芯之间的选择性透过膜3；所述吸附层2为70μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为63％，其中活性炭比表面积为1830m 2/g，粒径分布为D10：2.82μm，D50：6.33μm，D90：14.05μm，按重量计活性炭浆料中活性炭材料95份；所述胶粘剂为聚乙烯醇，为5份；所述溶剂为环己酮与碳酸丙烯酯；所述选择性透过膜3为偏四氟乙烯膜。电池化成后进行55℃循环(1000圈)实验，观察电芯循环前后厚度变化以及袋装电池内部产气量。
比较例7
基于高比表面积活性炭材料的可吸附气体的具有气袋的铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层 2；所述吸附层2为70μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为63％，其中活性炭比表面积为1830m 2/g，粒径分布为D10：2.82μm，D50：6.33μm，D90：14.05μm，按重量计活性炭浆料中活性炭材料95份；所述胶粘剂为聚乙烯醇，为5份；所述溶剂为乙腈与乙酸乙酯。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2的有气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电芯经45℃热压化成后剪去气袋二封，进行55℃循环(1000圈)实验，观察电芯循环前后厚度变化以及袋装电池内部产气量。
比较例8
基于高比表面积活性炭材料的可吸附气体的无气袋无选择性透过膜3的铝塑膜袋装电池，可吸附铝塑膜袋装电池包括含有涂覆在铝塑膜上的吸附层2；所述吸附层2为70μm，是由活性炭浆料经涂覆烘干辊压后制得。活性炭浆料固含量为63％，其中活性炭比表面积为1830m 2/g，粒径分布为D10：2.82μm，D50：6.33μm，D90：14.05μm，按重量计活性炭浆料中活性炭材料95份；所述胶粘剂为聚乙烯醇，为5份；所述溶剂为碳酸丙烯酯。
所述电池由NCM523正极石墨负极的卷绕裸电芯与上述含有吸附层2的无气袋铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。所制备电芯经45℃热压化成后，进行55℃循环(1000圈)实验，观察电芯循环前后厚度变化以及袋装电池内部产气量。
比较例9
所述电池由NCM523正极石墨负极的卷绕裸电芯与不含有吸附层2的铝塑膜封装袋构成，裸电芯尺寸为51*90*3.5mm。电池化成后抽真空二封剪去气袋进行55℃循环(1000圈)，观察电芯循环前后 厚度变化以及袋装电池内部产气量。
表3 55℃循环(1000圈)后产气量及电芯厚度变化
Figure PCTCN2022104942-appb-000005
由表3及图6可知，实施例3电池的容量保持率最佳，且在循环中容量衰减趋势更加线性，没有出现跳水现象，这是由于吸附层2吸 附了大量的气体，抑制了气体对电池的电化学性能影响。比较例7与比较例8，虽然具有吸附层2，然而没有选择性透过膜3，部分电解液被吸附层2吸附，从而使得电极浸润不充分，影响了电芯的初始性能，导致初始容量低。比较例9循环性能最差。
以上涉及到公知常识的内容不作详细描述，本领域的技术人员能够理解。
以上所述仅为本发明的一些具体实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。本项发明的技术性范围并不局限于说明书上的内容，必须要根据权利要求范围来确定其技术性范围。

Claims (12)

  1. 一种可吸附气体的金属复合膜，其特征在于：由铝塑膜、活性炭吸附层及选择性透过膜组成；所述活性炭吸附层设置于所述铝塑膜用于包装电池时接触电解液的内侧上；所述活性炭吸附层上覆盖一层面积大于活性炭吸附层的选择性透过膜。
  2. 根据权利要求1所述的可吸附气体的金属复合膜，其特征在于：所述活性炭吸附层由活性炭浆料经涂覆、干燥后形成；所述活性炭浆料包括活性炭材料、胶粘剂、溶剂。
  3. 根据权利要求2所述的可吸附气体的金属复合膜，其特征在于：所述活性炭浆料固含量为55～65％，其中固体份按重量计为92～95份的活性炭材料，5～8份的胶粘剂。
  4. 根据权利要求2所述的可吸附气体的金属复合膜，其特征在于：所述活性炭材料具有微孔、介孔与大孔兼具的三维分级多孔结构；其粒径分布为D10:1.40～2.90μm，D50:4.20～6.40μm，D90:8.20～14.10μm。
  5. 根据权利要求2所述的可吸附气体的金属复合膜，其特征在于：所述活性炭材料的比表面积为1600m 2/g～2100m 2/g。
  6. 根据权利要求2所述的可吸附气体的金属复合膜，其特征在于：所述胶粘剂为聚四氟乙烯、偏四氟乙烯、丁苯橡胶、聚乙烯醇、聚乙烯、聚丙烯中的至少一种。
  7. 根据权利要求1所述的可吸附气体的金属复合膜，其特征在于：所述选择性透过膜的材料选自聚四氟乙烯，偏四氟乙烯，尼龙6中的一种。
  8. 根据权利要求4所述的可吸附气体的金属复合膜，其特征在 于：所述活性炭材料粒径分布为D10:1.47～2.82μm，D50:4.23～6.33μm，D90:8.21～14.05μm；所述活性炭材料的比表面积为1689m 2/g～2100m 2/g。
  9. 根据权利要求5所述的可吸附气体的金属复合膜，其特征在于：所述活性炭材料的比表面积为1689m 2/g～2100m 2/g。
  10. 根据权利要求1所述的可吸附气体的金属复合膜，其特征在于：所述活性炭吸附层厚度40～70μm。
  11. 一种可吸附气体金属复合膜的制备方法，其特征在于，包括以下步骤：
    (1)活性炭浆料的制备：
    将活性炭材料、胶粘剂和溶剂混合，搅拌均匀即得所述活性炭浆料；所述活性炭浆料固含量为55～65％，其中固体份按重量计为92～95份的活性炭材料，5～8份的胶粘剂；
    (2)活性炭吸附层的形成：
    将制得的活性炭浆料均匀涂覆在所述铝塑膜用于包装电池时接触电解液的内侧上，经干燥后形成活性炭吸附层；
    (3)可吸附气体金属复合膜的制备：
    再在所述活性炭吸附层上覆盖一层面积大于活性炭吸附层的选择性透过膜，所述选择性透过膜是通过热塑形式固定在所述铝塑膜用于包装电池时接触电解液的内侧上。
  12. 一种袋装电池，其特征在于，包括如权利要求1～10中任一项所述的可吸附气体的金属复合膜。
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