WO2020098791A1 - 一种正极极片及电化学装置 - Google Patents

一种正极极片及电化学装置 Download PDF

Info

Publication number
WO2020098791A1
WO2020098791A1 PCT/CN2019/118843 CN2019118843W WO2020098791A1 WO 2020098791 A1 WO2020098791 A1 WO 2020098791A1 CN 2019118843 W CN2019118843 W CN 2019118843W WO 2020098791 A1 WO2020098791 A1 WO 2020098791A1
Authority
WO
WIPO (PCT)
Prior art keywords
adhesive layer
conductive
lithium
battery
pole piece
Prior art date
Application number
PCT/CN2019/118843
Other languages
English (en)
French (fr)
Inventor
李伟
史海浩
刘会会
靳超
徐建宝
李世松
郭超
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Publication of WO2020098791A1 publication Critical patent/WO2020098791A1/zh

Links

Images

Classifications

    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/38—Carbon pastes or blends; Binders or additives therein
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/48—Conductive polymers
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/668—Composites of electroconductive material and synthetic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/50—Methods or arrangements for servicing or maintenance, e.g. for maintaining operating temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • 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
    • Y02E60/13—Energy storage using capacitors

Definitions

  • the present application belongs to the field of electrochemical technology. More specifically, the present application relates to a positive pole piece and an electrochemical device including the positive pole piece.
  • Lithium ion batteries are widely used in electric vehicles and consumer electronic products due to their advantages such as high energy density, high output power, long cycle life, and low environmental pollution.
  • lithium-ion batteries are susceptible to fire and explosion when they are subject to abnormal conditions such as crushing, collision, or puncture, causing serious harm. Therefore, the safety of lithium-ion batteries greatly limits the application and popularization of lithium-ion batteries.
  • An object of the present application is to provide a pole piece and an electrochemical device with improved safety and electrical performance.
  • a further object of the present application is to provide a pole piece and an electrochemical device with good safety (especially the safety of piercing nails) and improved electrical performance (especially cycle performance).
  • the present application provides a positive electrode sheet including a current collector, a positive electrode active material layer, and an adhesive layer disposed between the current collector and the positive electrode active material layer, the adhesive layer containing a polymer material, a conductive material, and an inorganic filler, wherein
  • the polymer material includes an adhesive layer substrate, and the adhesive layer substrate is an oily polymer material whose solubility in NMP at 130 ° C. in 5 minutes is 30% or less of the solubility of PVDF under the same conditions.
  • the present application also provides an electrochemical device, which includes the positive pole piece of the present application, and the electrochemical device is preferably a capacitor, a primary battery, or a secondary battery.
  • FIG. 1 is a schematic structural diagram of a positive electrode sheet according to an embodiment of the present application, where 10—current collector; 14—positive electrode active material layer; 12—adhesive layer.
  • FIG. 2 is a perspective view of an embodiment of a lithium ion battery.
  • FIG. 3 is an exploded view of FIG. 2.
  • FIG. 4 is a perspective view of an embodiment of a battery module.
  • FIG. 5 is a perspective view of an embodiment of a battery pack.
  • Fig. 6 is an exploded view of Fig. 5.
  • FIG. 7 is a schematic diagram of an embodiment of a device using a lithium ion battery as a power source.
  • the present application discloses a positive electrode sheet, which includes a current collector, a positive electrode active material layer, and a glue layer disposed between the current collector and the positive electrode active material layer.
  • the adhesive layer includes a polymer material, a conductive material and an inorganic filler, wherein the polymer material includes an adhesive layer matrix, and the adhesive layer matrix has a solubility in NMP at 130 ° C. for 5 minutes, which is the solubility of PVDF under the same conditions 30% or less (ie, not more than 30%) of oily polymer materials.
  • FIG. 1 shows a schematic structural diagram of a positive electrode sheet according to some embodiments of the present application, in which 10-current collector, 14-positive electrode active material layer, and 12-gel layer.
  • FIG. 1 shows that the glue layer 12 and the positive electrode active material layer 14 are provided only on one side of the positive electrode current collector 10, in other embodiments, the positive electrode current collector 10 may be provided on both sides The glue layer 12 and the positive electrode active material layer 14.
  • the glue layer provided between the current collector and the positive electrode active material layer, it can play the role of wrapping the current collector and the metal burrs generated in the current collector under abnormal conditions such as nail penetration to prevent metal burrs or collection
  • the fluid is in direct contact with the counter electrode, thereby improving the safety performance of the positive pole piece and the electrochemical device for nail penetration.
  • a glue layer composed of a conventional polymer material (such as PVDF) and a conductive material provided between the current collector and the positive electrode active material layer
  • DCR Direct Current Internal Resistance
  • the present application starts from various aspects and adopts a variety of technical means to coordinate processing to improve the performance and stability of the glue layer provided between the current collector and the positive electrode active material layer.
  • the glue layer provided between the current collector and the positive electrode active material layer contains a polymer material, a conductive material, and an inorganic filler.
  • the composition of the adhesive layer of the present application will be separately introduced below.
  • the adhesive layer In order to make the adhesive layer have good ductility, and have good conductivity and stability, relative to the total weight of the adhesive layer (ie, the polymer material, conductive material, inorganic filler and optional other
  • the total weight of the auxiliary agent is regarded as 100%
  • the weight percentage of the polymer material is usually 35wt% -75wt%, preferably 40wt% -75wt%, more preferably 50wt% -75wt%.
  • the choice of polymer materials in the adhesive layer is also very important.
  • the base of the glue layer in the glue layer is an oily polymer material whose solubility in NMP within 130 ° C and 5 minutes is 30% or less of the solubility of PVDF under the same conditions.
  • the organic solvent such as NMP
  • the positive electrode active material layer is coated on top of the glue layer, the organic solvent (such as NMP) in the slurry of the positive electrode active material layer and the electrolyte will dissolve and swell the polymer material in the glue layer. Therefore, if the degree of dissolution and swelling is large, when the coating speed is fast, the positive electrode active material layer is likely to crack due to uneven stress, which will seriously affect production and production efficiency;
  • an oily polymer material with a solubility in NMP at 130 ° C. for 5 minutes of less than 30% of the solubility of PVDF under the same conditions is adopted as the substratum base material, and the substratum base material is regarded as “insoluble "Ingredients” can effectively hinder the dissolution and swelling of organic solvents (such as NMP, etc.) and electrolytes, which can solve the problems of cracking and the deterioration of battery DCR.
  • the substrate of the adhesive layer is at least one selected from polyacrylonitrile, polyacrylic acid, polyacrylate, polyacrylic acid-acrylate, polyacrylonitrile-acrylic acid, and polyacrylonitrile-acrylate.
  • the aqueous polymer material means that the polymer molecular chain is fully extended and dispersed in water
  • the oily polymer material means that the polymer molecular chain is fully extended and dispersed in the oily solvent.
  • the same type of polymer materials can be dispersed in water and oil by using suitable surfactants, that is, the same type of polymer materials can be made into high water Molecular materials and oily polymer materials.
  • a person skilled in the art may appropriately select oily polyacrylonitrile or oily polyacrylate as the base material (insoluble polymer material) of the glue layer according to needs.
  • the adhesive layer may further include a binder (that is, the polymer material in the adhesive layer includes a substrate of the adhesive layer and an optional binder).
  • the weight percentage of the adhesive layer substrate is greater than or equal to 20 wt% relative to the total weight of the adhesive layer.
  • the mechanism of action of the adhesive layer of the present application is to improve the safety performance of the nailing of the positive electrode and the electrochemical device by wrapping the current collector and metal burrs generated in the current collector under abnormal conditions such as nail penetration, the adhesive layer and the current collector
  • the binding force between the two should not be too small, otherwise it may not be possible to guarantee the effective and reliable wrapping of the current collector and metal burrs generated in the current collector under abnormal conditions such as nail penetration.
  • the binder may be fluorinated polyolefin and / or chlorinated polyolefin, preferably polyvinylidene fluoride (PVDF), carboxylic acid modified PVDF, acrylic acid modified PVDF, polyvinylidene chloride (PVDC), carboxyl At least one of acid-modified PVDC, acrylic-modified PVDC, PVDF copolymer, and PVDC copolymer.
  • PVDF polyvinylidene fluoride
  • PVDC polyvinylidene chloride
  • the addition of the above-mentioned binder has a significant improvement effect on improving the safety performance of battery nailing.
  • the weight percentage of the adhesive layer matrix is 30wt% -100wt%
  • the weight percentage of the binder is 0wt% -70wt%.
  • the weight percentage of fluorinated polyolefin and / or chlorinated polyolefin is not less than 15% by weight based on the total weight of the subbing layer. At this amount, the adhesion between the adhesive layer and the current collector is greater, which has a significant improvement effect on improving the safety of nail penetration.
  • the solvent such as NMP, etc.
  • electrolyte in the positive electrode active material layer on the upper layer of the glue layer will adversely affect the dissolution and swelling of the polymer material in the glue layer, thereby The adhesive layer will be destroyed, affecting the stability of the adhesive layer.
  • the inorganic filler is equivalent to a barrier substance, which is conducive to eliminating the above-mentioned adverse effects of dissolution and swelling, and is conducive to stabilizing the adhesive layer.
  • the addition of inorganic fillers also helps to ensure that the adhesive layer is not easily deformed during the compaction of the pole piece. Therefore, the addition of the inorganic filler can ensure that the glue layer is stable between the current collector and the positive electrode active material layer, and prevent the current collector from directly contacting the positive electrode active material layer, thereby improving the safety performance of the battery.
  • the inorganic filler can play the role of stabilizing the glue layer from the following two aspects: (1) hinder the solvent (such as NMP, etc.) in the positive electrode active material layer or the electrolyte from dissolving and swelling the polymer material in the glue layer And other undesirable effects; (2) helps to ensure that the adhesive layer is not easily deformed during the compaction of the pole piece.
  • hinder the solvent such as NMP, etc.
  • the weight percentage of the inorganic filler is usually 10 wt% -60wt%. If the content of the inorganic filler is too small, it is not enough to stabilize the adhesive layer; if the content is too large, the ductility and other properties of the adhesive layer will be affected.
  • the weight percentage of the inorganic filler is preferably 15% to 45% by weight.
  • the average particle diameter D of the inorganic filler in the subbing layer satisfies 100 nm ⁇ D ⁇ 10 ⁇ m, and more preferably 1 ⁇ m ⁇ D ⁇ 6 ⁇ m.
  • the specific surface area (BET) of the inorganic filler in the subbing layer is not greater than 500 m 2 / g.
  • the specific surface area of the inorganic filler increases, side reactions will increase the performance of the battery; and when the specific surface area of the inorganic filler is too large, a higher proportion of binder needs to be consumed, which will cause The bonding force is reduced, and the internal resistance growth rate is higher.
  • the specific surface area (BET) of the inorganic filler is not more than 500 m 2 / g, a better comprehensive effect can be provided.
  • the inorganic filler is selected from at least one of metal oxides, non-metal oxides, metal carbides, non-metal carbides, and inorganic salts, or conductive carbon coating modification, conductive metal coating modification of the above materials or The conductive polymer coats at least one of the modified materials.
  • the inorganic filler may be selected from magnesium oxide, alumina, titania, zirconia, silica, silicon carbide, boron carbide, calcium carbonate, aluminum silicate, calcium silicate, potassium titanate, barium sulfate, cobalt acid Lithium, lithium manganate, lithium nickelate, lithium nickel manganate, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminate, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium iron silicate, silicic acid At least one of lithium vanadium, lithium cobalt silicate, lithium manganese silicate, lithium titanate, or the conductive carbon coating modification, conductive metal coating modification or conductive polymer coating modification of the above materials At least one.
  • the inorganic filler in addition to the above-mentioned role of stabilizing the adhesive layer (which prevents the organic solvent from dissolving and swelling the polymer material and ensuring that the adhesive layer is not easily deformed), the inorganic filler can also play the following two The role of:
  • the electrochemically active material has the characteristics of intercalation and deintercalation of lithium ions, during the overcharge process, the electrochemically active material will be delithiated and it becomes more and more difficult to delithiate, and the impedance continues to increase.
  • the heat generation power increases, and the temperature of the adhesive layer increases faster, which causes the volume of the polymer material in the adhesive layer to increase, and the conductive network composed of the conductive material in the adhesive layer is "destroyed".
  • the resistance in the battery is increased, which can improve the overcharge safety performance of the battery;
  • Contribution of charge and discharge capacity Since the electrochemically active material can contribute a certain charge and discharge capacity at the normal operating temperature of the battery, it can be made at the normal operating temperature The effect of the lower adhesive layer on the battery's capacity and other electrochemical properties is minimized.
  • the positive electrode electrochemically active material or the positive electrode electrochemically active material of the conductive carbon coating modification, the conductive metal coating modification or the conductive polymer coating modified material is used as the Inorganic fillers are the most preferred.
  • the positive electrode electrochemically active material is preferably selected from lithium cobaltate, lithium nickel manganese cobaltate, lithium nickel manganese aluminate, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium iron manganese phosphate, silicic acid Lithium iron, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel lithium manganate, spinel lithium nickel manganate, lithium titanate, or their conductive carbon coating modified materials, At least one of a conductive metal-coated modified material or a conductive polymer-coated modified material.
  • these electrochemically active materials modified by conductive carbon coating such as conductive carbon coated modified lithium cobalt oxide, conductive carbon coated modified nickel manganese lithium cobalt oxide, conductive carbon coated modified nickel manganese Lithium aluminate, conductive carbon coated modified lithium iron phosphate, conductive carbon coated modified lithium vanadium phosphate, conductive carbon coated modified lithium cobalt phosphate, conductive carbon coated modified lithium manganese phosphate, conductive carbon Coated modified lithium iron manganese phosphate, conductive carbon coated modified lithium iron silicate, conductive carbon coated modified lithium vanadium silicate, conductive carbon coated modified lithium cobalt silicate, conductive carbon coated Modified lithium manganese silicate, conductive carbon coated modified spinel lithium manganate, conductive carbon coated modified spinel lithium nickel manganate, conductive carbon coated modified lithium titanate At least one.
  • conductive carbon coated modified lithium cobalt oxide such as conductive carbon coated modified lithium cobalt oxide, conductive carbon coated modified nickel manganese lithium cobalt oxide, conductive carbon coated modified nickel manga
  • electrochemically active materials and conductive carbon-coated modified electrochemically active materials are commonly used materials in the manufacture of lithium batteries, and most of them can be purchased directly through commercial channels.
  • the types of conductive carbon can be graphite, graphene, conductive carbon black, carbon nanotubes, etc.
  • the electrical conductivity of the inorganic filler can be adjusted by adjusting the coating content of the conductive carbon.
  • the first reason is that lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate and other substances have high safety performance and do not release oxygen when overcharged.
  • the second is relative to lithium cobalt oxide, For materials such as lithium nickel manganese cobalt oxide, the resistance of the above materials increases more during overcharging, so that the adhesive layer generates more heat, which can enhance the effect of improving the safety of battery overcharging.
  • the conductivity ⁇ of the inorganic filler when the conductivity ⁇ of the inorganic filler satisfies 10 -3 S / m ⁇ 10 2 S / m, it will bring additional benefits.
  • the inventor has found that the addition of inorganic fillers will affect the conductive properties of the adhesive layer, which in turn may affect the conductivity of the entire pole piece.
  • the conductivity ⁇ of the inorganic filler satisfies 10 -3 S / m ⁇ 10 2 S / m, the conductive performance of the adhesive layer at the normal use temperature of the battery can be improved.
  • the conductivity ⁇ of the inorganic filler is too small, the initial internal resistance and the growth rate of the internal resistance of the adhesive layer will be high; if the ⁇ is too high, the conductive network is not easy to be cut off, which is not conducive to improving the safety of overcharge and nail penetration.
  • the conductivity ⁇ of certain inorganic fillers does not satisfy 10 -3 S / m ⁇ 10 2 S / m, the conductivity can be made by material modification or modification methods commonly used in the art Meet the above requirements.
  • controlling the ratio of the polymer material to the conductive material is beneficial to improve the performance of the adhesive layer.
  • the adhesive layer includes a conductive material in addition to the polymer material and the inorganic filler.
  • the glue layer In order for the electrochemical device to perform electrochemical reactions normally under normal working conditions, the glue layer must contain a certain amount of conductive material. If the content of the conductive material is too low, it is not conducive to the electrochemical reaction of the electrochemical device under normal working conditions, and the internal resistance is too large; if the content of the conductive material is too high, the conductive network is not easily damaged, which is not conducive to the electrochemical device Improvement of overcharge safety performance.
  • the weight percentage of the conductive material is 5 wt% -25wt%, preferably 5wt% -20wt%.
  • the weight ratio of the polymer material to the conductive material in the adhesive layer is greater than or equal to 2, preferably 3 to 8.
  • the conductive material may be selected from at least one of a conductive carbon-based material, a conductive metal material, and a conductive polymer material.
  • the conductive carbon-based material is at least one selected from conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes, and carbon nanofibers;
  • the conductive metal material is selected from at least one of Al powder, Ni powder, and gold powder
  • the conductive polymer material is selected from at least one of conductive polythiophene, conductive polypyrrole, and conductive polyaniline.
  • the conductive material may be used alone or in combination of two or more.
  • the conductive material is usually used in the form of powder or granules. Depending on the specific application environment, its particle size may be 5nm-500nm, such as 10nm-300nm, 15nm-200nm, 15nm-100nm, 20nm-400nm, 20nm-150nm, etc.
  • the adhesive layer of the present application can be formed by conventional methods. For example, by dissolving polymer materials, conductive materials, inorganic fillers and optional other additives in a solvent and stirring to form a slurry, and then coating the slurry on the current collector, heating and drying can get the desired Glue layer.
  • the adhesive layer of the present application may consist essentially of the polymer material (including the adhesive layer matrix and the optional binder), conductive material, and inorganic filler, that is, free of Significant amounts (eg, content ⁇ 3%, ⁇ 1%, or ⁇ 0.5%) of other components.
  • the glue layer directly adheres to the current collector and is disposed between the current collector and the positive electrode active material layer.
  • the thickness H of the adhesive layer can be reasonably determined according to actual needs.
  • the thickness H of the adhesive layer is usually not greater than 40 ⁇ m, preferably not greater than 25 ⁇ m, and more preferably not greater than 20 ⁇ m, 15 ⁇ m or 10 ⁇ m.
  • the coating thickness of the adhesive layer is usually 1 ⁇ m or more, preferably 2 ⁇ m or more, and more preferably 3 ⁇ m or more.
  • the thickness is too small, it is not enough to ensure the effect of the adhesive layer to improve the safety performance of the battery; if it is too large, it will cause the internal resistance of the battery to increase seriously, thereby affecting the electrochemical performance of the battery during normal operation.
  • the bonding force between the adhesive layer and the current collector is preferably equal to or greater than 10 N / m.
  • the glue layer and the positive electrode active material layer are not easy to separate after coating and drying. Therefore, in this application, the glue layer and the positive electrode active material layer are collectively referred to as a membrane layer. Therefore, the bonding force between the membrane layer and the current collector is equivalent to the bonding force between the adhesive layer and the current collector.
  • the large binding force can ensure that the adhesive layer can effectively and reliably wrap the current collector and the metal burrs generated in the current collector under abnormal conditions such as nail penetration.
  • the inventor also found that in the present application, the elongation rate of the membrane layer has a certain influence on the safety performance of the nailing of the pole piece.
  • the elongation rate is generally not more than 1%, and it cannot play the role of wrapping the metal burr, so the exposed metal burr is easy to cause Short circuit in the battery.
  • the elongation rate of the membrane layer has been greatly improved, which can wrap the metal burrs that may be generated in the current collector to prevent the occurrence of short circuits in the battery, thereby greatly improving the battery The safety of nailing.
  • the elongation of the membrane layer is greater than or equal to 30%, preferably greater than or equal to 80%.
  • the advantage of the larger elongation rate is that under abnormal conditions such as nail penetration, the membrane layer with greater elongation rate can wrap the metal burrs that may be generated in the current collector to prevent the occurrence of short circuits in the battery, thereby greatly improving the battery nailing safety Sex.
  • the elongation of the membrane layer can be adjusted by changing the type, relative dosage, molecular weight, degree of crosslinking, etc. of the polymer material in the adhesive layer. If the content of the polymer material in the adhesive layer is increased, it will inevitably contribute to the improvement of the elongation of the membrane layer. However, if the content of the polymer material in the adhesive layer is too large, the content of the conductive material will be relatively low, thereby causing the DCR of the battery to increase greatly during normal operation. Therefore, it is preferable that the elongation of the membrane layer is 80% or more and 300% or less.
  • the current collector materials commonly used in the art may be used, and metal current collectors such as stainless steel, aluminum, copper, titanium and other metal sheets or metal foils are preferred.
  • the current collector is an aluminum-containing porous current collector (for example, porous aluminum foil). Due to the reduction of the aluminum metal content per unit area in the thickness direction of the cell, under abnormal conditions such as nail penetration, the use of porous aluminum foil can reduce the probability of occurrence of metal burrs, and thereby reduce the probability of occurrence of severe aluminothermic reaction, so it can be further Improve the safety of electrochemical devices.
  • porous aluminum foil can also improve the electrolyte infiltration pole piece, and thereby improve the dynamic performance of lithium ion batteries; and the adhesive layer can cover the surface of the porous aluminum foil to prevent the upper active material layer from leaking during the coating Tu phenomenon.
  • the proportion of the pore area of the aluminum-containing porous current collector is preferably 5% to 75%.
  • the elongation at break ⁇ of the current collector is preferably 0.8% ⁇ ⁇ ⁇ 4%. It has been found that if the elongation at break of the current collector is too large, the metal burrs are large when punctured, which is not conducive to improving the safety performance of the battery; otherwise, if the elongation at break of the current collector is too small, it is compacted at the pole piece It is easy to break during processing or when the battery is pressed or collided, which reduces the quality or safety of the battery. Therefore, in order to further improve safety, especially nailing safety, the elongation at break ⁇ of the current collector should be no more than 4% and no less than 0.8%.
  • the elongation at break of the metal current collector can be adjusted by changing the purity, impurity content and additives of the metal current collector, billet production process, rolling speed, heat treatment process, etc.
  • the thickness of the current collector is preferably 4 ⁇ m to 16 ⁇ m.
  • the positive electrode active material layer used in the positive electrode sheet of the present application can be selected from various conventional positive electrode active material layers commonly used in the art, and its composition and preparation method are well known in the art and are not particularly limited.
  • the positive electrode active material layer contains a positive electrode active material, and various positive electrode active materials known to those skilled in the art for preparing a positive electrode of a lithium ion secondary battery can be used.
  • the positive electrode active material is a lithium-containing composite metal oxide, specifically
  • the material is, for example, one or more of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiFePO 4 , lithium nickel cobalt manganese oxide (such as LiNi 0.5 Co 0.2 Mn 0.3 O 2 ) and one of lithium nickel manganese oxide kind or several.
  • the positive electrode electrochemically active material (or its coating modified material) is used as the inorganic filler of the gel layer of the positive electrode sheet, the positive electrode electrochemically active material in the gel layer and the positive electrode activity used in the positive electrode active material layer
  • the substances can be the same or different.
  • the present application also discloses an electrochemical device including the positive pole piece according to the present application.
  • the electrochemical device may be a capacitor, a primary battery, or a secondary battery.
  • it may be a lithium ion capacitor, a lithium ion primary battery, or a lithium ion secondary battery.
  • the construction and preparation methods of these electrochemical devices are known per se.
  • the negative electrode tab may include a negative electrode current collector and a negative electrode active material layer provided on the negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material, a binder, a conductive material, and the like.
  • the negative electrode active material is, for example, a carbonaceous material such as graphite (artificial graphite or natural graphite), conductive carbon black, carbon fiber, etc., for example, metal or semi-metallic materials such as Si, Sn, Ge, Bi, Sn, In or their alloys, containing lithium Nitride or lithium-containing oxide, lithium metal or lithium aluminum alloy, etc.
  • a carbonaceous material such as graphite (artificial graphite or natural graphite), conductive carbon black, carbon fiber, etc.
  • metal or semi-metallic materials such as Si, Sn, Ge, Bi, Sn, In or their alloys, containing lithium Nitride or lithium-containing oxide, lithium metal or lithium aluminum alloy, etc.
  • the electrochemical device may have improved safety (such as nail-penetrating safety) and electrical performance.
  • the positive electrode tab of the present application is easy to process, so the manufacturing cost of the electrochemical device using the positive electrode tab of the present application can be reduced.
  • the electrochemical device is a lithium ion battery.
  • FIG. 2 is a perspective view of an embodiment of a lithium ion battery 5.
  • FIG. 3 is an exploded view of FIG. 2. 2 to 3, the lithium ion battery 5 includes a case 51, an electrode assembly 52, a top cover assembly 53, and an electrolyte (not shown).
  • the electrode assembly 52 is accommodated in the case 51.
  • the number of electrode assemblies 52 is not limited, and may be one or more.
  • the electrode assembly 52 includes a positive pole piece, a negative pole piece, and a separator.
  • the separator separates the positive pole piece from the negative pole piece.
  • the electrolyte is injected into the case 51 and impregnates the electrode assembly 52, which includes, for example, a first pole piece, a second pole piece, and a separator.
  • the lithium-ion battery 5 shown in FIG. 2 is a can-type battery, but it is not limited thereto.
  • the lithium-ion battery 5 may be a pouch-type battery, that is, the case 51 is replaced by a metal plastic film and the top cover assembly 53 is eliminated.
  • FIG. 4 is a perspective view of an embodiment of the battery module 4.
  • the battery module 4 provided by the embodiment of the present application includes the lithium ion battery 5 of the present application.
  • the battery module 4 includes a plurality of batteries 5.
  • a plurality of lithium ion batteries 5 are arranged in the longitudinal direction.
  • the battery module 4 can serve as a power source or an energy storage device.
  • the number of lithium ion batteries 5 in the battery module 4 can be adjusted according to the application and capacity of the battery module 4.
  • FIG. 5 is a perspective view of an embodiment of the battery pack 1.
  • Fig. 6 is an exploded view of Fig. 5.
  • the battery pack 1 provided by the present application includes the battery module 4 according to an embodiment of the present application.
  • the battery pack 1 includes an upper case 2, a lower case 3 and a battery module 4.
  • the upper case 2 and the lower case 3 are assembled together and form a space for accommodating the battery module 4.
  • the battery module 4 is placed in the space of the upper case 2 and the lower case 3 assembled together.
  • the output pole of the battery module 4 passes through one or both of the upper case 2 and the lower case 3 to supply power to or charge from the outside.
  • the number and arrangement of battery modules 4 used in the battery pack 1 can be determined according to actual needs.
  • FIG. 7 is a schematic diagram of an embodiment of a device using a lithium ion battery as a power source.
  • the device provided by the present application includes the lithium ion battery 5 according to an embodiment of the present application, and the lithium ion battery 5 can be used as a power source of the device.
  • the device using the lithium ion battery 5 is an electric car.
  • the device using the lithium-ion battery 5 may be any electric vehicle (for example, electric bus, electric tram, electric bicycle, electric motorcycle, electric scooter, electric golf cart, electric truck) other than electric cars ), Electric ships, electric tools, electronic equipment and energy storage systems.
  • the electric vehicle may be an electric pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • the device provided in this application may include the battery module 4 described in this application.
  • the device provided in this application may also include the battery pack 1 described in this application.
  • Adhesive layer Adopting a certain proportion of adhesive layer substrate, optional binder, conductive material, inorganic filler, using N-methyl-2-pyrrolidone (NMP) as a solvent, evenly mixed and coated on the metal set On both surfaces of the fluid, an adhesive layer was obtained after drying at 85 ° C.
  • NMP N-methyl-2-pyrrolidone
  • Positive electrode active material layer Then, 90wt% positive electrode active material, 5wt% SP and 5wt% PVDF are mixed with NMP as a solvent, and then evenly coated on the adhesive layer of the current collector prepared according to the above method; at 85 After drying at °C, a positive electrode active material layer is obtained.
  • Substrate substrate polyacrylonitrile, polyacrylonitrile-acrylate, polyacrylate;
  • Positive electrode active material NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O 2 );
  • Binder PVDF (manufacturer "Solvay”, model 5130);
  • Conductive material conductive agent: Super-P (Swiss TIMCAL company, referred to as SP);
  • Inorganic fillers alumina, carbon-coated modified lithium iron phosphate (abbreviated as LFP / C), carbon-coated modified lithium titanate (abbreviated as Li 4 Ti 5 O 12 / C).
  • the above materials are common and commonly used materials in the field of lithium battery industry, and can be easily obtained through corresponding suppliers through commercial channels.
  • Negative pole piece Add active material graphite, conductive agent Super-P, thickener CMC, adhesive SBR according to the mass ratio of 96.5: 1.0: 1.0: 1.5 to the solvent deionized water and mix to make anode slurry; The slurry is coated on the surface of the negative electrode metal current collector copper foil and dried at 85 ° C, then trimmed, cut, and slitted, and then dried at 110 ° C for 4 hours under vacuum conditions, and welded to the ear The negative pole piece of the secondary battery that meets the requirements.
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 3: 5: 2 to obtain an EC / EMC / DEC mixed solvent, followed by fully drying the lithium salt LiPF 6 Dissolve in a mixed solvent to obtain a solution with a concentration of 1M, that is, an electrolyte.
  • separator Using a 12 ⁇ m polypropylene film as the separator, stack the positive pole piece, the separator and the negative pole piece in order, so that the separator is in the middle of the positive pole piece and the negative pole piece to play the role of isolation, and then wound into a bare battery core.
  • Vacuum-bake at 75 ° C for 10 hours inject the electrolyte (prepared as described in "Preparation of Electrolyte” above), vacuum encapsulate and let stand for 24 hours, then charge to 4.2V with a constant current of 0.1C, and then Charge at a constant voltage of V until the current drops to 0.05C, then discharge to 3.0V at a constant current of 0.1C, repeat the charge and discharge twice, and finally charge to 3.8V at a constant current of 0.1C, that is, the preparation of the secondary battery is completed.
  • the powder sample of the material is dispersed in a dispersion medium (distilled water), and a Malvern laser particle size analyzer MS2000 is used, and the average value is measured 5 times and the unit is ⁇ m.
  • a dispersion medium distilled water
  • MS2000 Malvern laser particle size analyzer MS2000
  • the specific surface area of the powder sample of the material was tested with a Quadrasorb SI specific surface tester, and the average value was measured 5 times and the unit was m 2 / g.
  • Thickness of adhesive layer, thickness of diaphragm layer measure the thickness of the current collector, measure the total thickness after coating the adhesive layer, and use the difference between the two as the thickness of the adhesive layer.
  • the thickness of the diaphragm layer adopts a similar method.
  • the absence of cracks in the 100 m 2 pole piece is defined as no cracking.
  • the polymer material is made into a 7 ⁇ m thick film, cut into 20mm * 50mm strips, weighed and recorded as M1;
  • NMP N-methylpyrrolidone
  • solubility of PVDF manufactured by manufactureurer "Solvay", model 5130
  • Solvay model 5130
  • the ratio of the solubility of other materials to the solubility of PVDF is recorded.
  • GBT31485-2015 Safety requirements and test methods for power batteries for electric vehicles was used to evaluate the safety of the secondary batteries of the examples and comparative examples, and the test results were recorded.
  • the high temperature resistant steel needle (the cone angle of the needle tip is 45 °), penetrates at a speed of 25mm / s from the direction perpendicular to the battery plate, the penetration position should be close to the geometric center of the puncture surface, the steel needle stays in the battery, Observe whether the battery is burning or exploding.
  • the test conditions for the number of cycles are as follows: at 25 ° C, the secondary battery is subjected to a 1C / 1C cycle test, and the charging and discharging voltage range is 2.8 to 4.2V, and the capacity is reduced to 80% of the first discharge specific capacity to stop the test, and the cycle number is recorded.
  • the secondary battery was adjusted to 50% SOC at a current of 1C, and the voltage U1 was recorded. Then discharge at a current of 4C for 30 seconds, and record the voltage U2.
  • DCR (U1-U2) / 4C.
  • the DCR of a battery cell containing only PVDF as a polymer material is used as a reference and recorded as 100%, and the DCR of other cells and its ratio are calculated and recorded.
  • polyacrylonitrile, polyacrylonitrile-acrylate, and polyacrylate are all oily polymer materials whose solubility in NMP at 130 ° C. within 5 minutes is less than 30% of the solubility of PVDF under the same conditions. It is used as the base material of the adhesive layer in this application.
  • the corresponding adhesive layer, positive electrode sheet, and negative electrode were prepared according to the methods and steps described in "1. Preparation Method” Chips and batteries, and then test in accordance with the method specified in the "3. Battery Performance Test” section. In order to ensure the accuracy of the data, 4 batteries of each type (20 batteries used for acupuncture test or overcharge test) are prepared and tested independently. The final test results are averaged and shown in Table 1-2.
  • the conventional pole piece P is basically prepared according to the method described in "1.1 Preparation of the positive pole piece", but no glue layer is provided, that is, the positive electrode active material layer is directly coated on the current collector, and the conventional pole piece N is prepared according to "1.2 Negative pole Preparation of tablets ".
  • the corresponding adhesive layer and positive electrode were prepared according to the methods and steps described in "1. Preparation Method” And the negative electrode and the battery, and then perform the test according to the method specified in the “3. Battery Performance Test” section. In order to ensure the accuracy of the data, 4 batteries of each type (20 batteries used for acupuncture test or overcharge test) are prepared and tested independently. The final test results are averaged and summarized in Table 2-2.
  • the weight percentage of the polymer material is 35wt% -75wt%
  • the weight percentage of the conductive material is 5wt% -25wt%.
  • the weight percentage of the inorganic filler is 10wt% -60wt%.
  • the content of each component of the adhesive layer is within the above range, the effect of improving the safety and electrical performance (such as cycle performance) of the battery can be achieved.
  • Table 4-1 and Table 4-2 show that when the binder PVDF is added to the adhesive layer, the safety performance of the battery is further improved, especially when the content of PVDF is above 15wt%; PVDF dissolves and swells more in NMP, so it will deteriorate the DCR of the battery and cause coating cracking problems when the content of polyacrylonitrile is too small.
  • pole piece of the present application is only illustrated with a lithium battery as an example, but the pole piece of the present application can also be applied to other types of batteries or electrochemical devices, and the Good technical effect.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Materials Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

一种正极极片及电化学装置。该正极极片包括集流体(10)、正极活性材料层(14)和设置于集流体与正极活性材料层之间的胶层(12)，所述胶层(12)包含高分子材料、导电材料和无机填料，其中所述高分子材料包含胶层基体，所述胶层基体为在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下的油性高分子材料。该正极极片可以改善电化学装置(例如电容器、一次电池或二次电池等)在穿钉等异常情况下的穿钉安全性。

Description

一种正极极片及电化学装置
相关申请的交叉引用
本申请要求享有于2018年11月16日提交的名称为“一种正极极片及电化学装置”的中国专利申请201811366437.1的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请属于电化学技术领域，更具体地说，本申请涉及一种正极极片和包括该正极极片的电化学装置。
背景技术
锂离子电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而被广泛应用于电动汽车以及消费类电子产品中。然而锂离子电池在受到挤压、碰撞或穿刺等异常情况时很容易发生着火、爆炸，从而引起严重危害。因此锂离子电池的安全问题很大程度地限制了锂离子电池的应用和普及。
虽然研究人员提出了很多方法来提高电池的安全性，但是对于电池被穿刺所造成的安全隐患仍然缺乏非常有效的手段。有鉴于此，确有必要提供一种能够改善电池安全性、尤其是穿钉安全性的电池。
发明内容
本申请的一个目的在于：提供一种具有改善的安全性和电性能的极片及电化学装置。
本申请的进一步目的在于：提供一种具有良好的安全性(尤其是穿钉安全性)和改善的电性能(尤其是循环性能)的极片及电化学装置。
本申请提供了一种正极极片，包括集流体、正极活性材料层和设置于集流体与正极活性材料层之间的胶层，所述胶层包含高分子材料、导电材料和无机填料，其中所述高分子材料包含胶层基体，所述胶层基体为在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下的油性高分子材料。
本申请还提供了一种电化学装置，其包括本申请的正极极片，所述电化学装置优选为电容器、一次电池或二次电池。
附图说明
下面结合附图和具体实施方式，对本申请的正极极片、电化学装置及其有益效果进行详细说明。
图1为根据本申请的一个实施方式所描述的正极极片的结构示意图，其中10—集流体；14—正极活性材料层；12—胶层。
图2是锂离子电池的一实施方式的立体图。
图3是图2的分解图。
图4是电池模块的一实施方式的立体图。
图5是电池包的一实施方式的立体图。
图6是图5的分解图。
图7是锂离子电池作为电源的装置的一实施方式的示意图。
其中，附图标记说明如下：
1电池包
2上箱体
3下箱体
4电池模块
5电池
51壳体
52电极组件
53顶盖组件
具体实施方式
本申请公开了一种正极极片，包括集流体、正极活性材料层和设置于集流体与正极活性材料层之间的胶层。该胶层包含高分子材料、导电材料和无机填料，其中所述高分子材料包含胶层基体，所述胶层基体为在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下(即，不大于30％)的油性高分子材料。
图1示出了根据本申请某些实施例的正极极片的结构示意图，其中10—集流体，14—正极活性材料层，12—胶层。
易于理解的是，虽然图1中示出的是仅在正极极集流体10的单面设置胶层12和正极活性材料层14，但在其他实施例中，正极集流体10可以在双面设置胶层12和正极活性材料层14。
由于设置于集流体与正极活性材料层之间的胶层延展性高，因此在穿钉等异常情况下可以起到包裹集流体以及集流体中产生的金属毛刺的作用，以防止金属毛刺或集流体与对电极直接接触，由此改善正极极片和电化学装置的穿钉安全性能。
发明人发现，若采用由常规的高分子材料(例如PVDF)和导电材料组成设置于集流体与正极活性材料层之间的胶层的话，一来可能会存在正极活性材料层的开裂问题，二来可能会恶化电池的DCR(直流内阻)，三来在对正极活性材料层进行压实等处理后，胶层可能易变形，由此无法有效地起到改善安全的作用。
为了克服以上缺陷，本申请从多个方面着手，采用多种技术手段协同处理来改善设置于集流体与正极活性材料层之间的胶层的性能和稳定性。
设置于集流体与正极活性材料层之间的胶层包含高分子材料、导电材料、无 机填料。下面对本申请的胶层的组成成分分别进行介绍。
首先，发明人发现，可以通过对胶层中高分子材料的选择来提高胶层的稳定性和性能。
为了使得胶层具有较好的延展性，并兼具良好的导电性和稳定性，相对于所述胶层的总重量(即，将高分子材料、导电材料、无机填料和任选存在的其他助剂的总重量视为100％)，所述高分子材料的重量百分比通常为35wt％-75wt％，优选为40wt％-75wt％，更优选为50wt％-75wt％。
此外，胶层中高分子材料的种类选择也很重要。
一)、关于本申请中胶层基体的材料的选择
本申请公开的正极极片中，其胶层中的胶层基体为在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下的油性高分子材料。
若不对胶层基体的材料进行选择性采用，即采用常规的高分子材料(例如PVDF)，则易带来如下技术问题：
(1)在胶层的上方涂布正极活性材料层时，由于正极活性材料层的浆料中的有机溶剂(如NMP等)以及电解液会对胶层中的高分子材料产生溶解、溶胀，因此若上述溶解、溶胀程度较大，则在涂布速度较快时，则易于由于应力不均导致正极活性材料层的开裂，由此会严重影响生产和生产效率；
(2)若上述溶解、溶胀程度较大，则由于胶层的引入，会恶化电池DCR，不利于电池的动力学性能改善。
因此，在本申请中，采用在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下的油性高分子材料作为胶层基体材料，该胶层基体材料作为“难溶成分”可有效阻碍有机溶剂(如NMP等)和电解液对其的溶解、溶胀，从而可解决开裂问题和电池DCR恶化的问题。
所述胶层基体选自聚丙烯腈、聚丙烯酸、聚丙烯酸酯、聚丙烯酸-丙烯酸酯、聚丙烯腈-丙烯酸、聚丙烯腈-丙烯酸酯中的至少一种。
在本申请中，水性高分子材料是指高分子分子链完全伸展开分散在水中，油性高分子材料是指高分子分子链完全伸展开分散在油性溶剂中。本领域技术人员理解，通过采用合适的表面活性剂可以将同一类的高分子材料分别分散在水中和油中，即通过采用合适的表面活性剂同一类的高分子材料可以为分别做成水性高分子材料和油性高分子材料。例如，本领域技术人员可以根据需要，适当选用油性聚丙烯腈或油性聚丙烯酸酯作为胶层基体材料(难溶高分子材料)。
为了增强胶层与集流体之间的粘结力，所述胶层还可包含粘结剂(即胶层中的高分子材料包含胶层基体和任选存在的粘结剂)。
为了使得上述胶层基体起到较明显的“阻碍溶解、溶胀”的作用，优选相对于所述胶层的总重量，所述胶层基体的重量百分比为大于等于20wt％。
二)、关于本申请中粘结剂的材料的选择
由于本申请胶层的作用机理是在穿钉等异常情况下通过包裹集流体以及集流体中产生的金属毛刺，来改善正极极片和电化学装置的穿钉安全性能，因此胶层与集流体之间的结合力不能过小，否则可能无法保证有效地、可靠地在穿钉等异常情况下包裹集流体以及集流体中产生的金属毛刺。
为了提高胶层与集流体之间的结合力，发明人发现，可以在胶层中添加粘结剂。所述粘结剂可以是氟化聚烯烃和/或氯化聚烯烃，优选聚偏氟乙烯(PVDF)、羧酸改性的PVDF、丙烯酸改性的PVDF、聚偏氯乙烯(PVDC)、羧酸改性的PVDC、丙烯酸改性的PVDC、PVDF共聚物、PVDC共聚物中的至少一种。
上述粘结剂的添加对于改善电池穿钉安全性能具有明显的改进作用。
当然基于胶层基体材料的选择，也可以选择不添加任何粘结剂。
基于所述高分子材料的重量为100％(即相对于胶层中的高分子材料的总重量)，
所述胶层基体的重量百分比为30wt％-100wt％，
所述粘结剂的重量百分比为0wt％-70wt％。
导电材料和无机填料的含量一定的情况下，粘结剂的含量过大，则作为“难溶成分”的胶层基体的含量会过小，则无法保证可以完全解决涂层开裂和电池DCR恶化的问题。
优选地，基于胶层的总重量为100％，氟化聚烯烃和/或氯化聚烯烃的重量百分含量不小于15wt％。在这种用量下，胶层与集流体之间的粘结力较大，对于改善穿钉安全具有较明显的改善效果。
其次，发明人发现，在胶层中加入无机填料可以起到稳定胶层的作用。
已发现当胶层中不含有无机填料时，处于胶层上层的正极活性材料层中的溶剂(如NMP等)或电解液会对胶层中的高分子材料产生溶解、溶胀等不良影响，从而胶层会遭到破坏，影响胶层的稳定性。在添加了无机填料后，该无机填料相当于一种阻隔物质，从而有利于消除上述溶解、溶胀等不良影响，有利于稳定胶层。此外，还发现无机填料的添加还有利于保证在极片压实过程中，胶层不易变形。因此无机填料的添加可以很好地保证胶层稳定地处于集流体与正极活性材料层之间，防止集流体与正极活性材料层直接接触，从而可以改善电池的安全性能。
概括而言，无机填料可以从如下两方面起到稳定胶层的作用：(1)阻碍正极活性材料层中的溶剂(如NMP等)或电解液对胶层中的高分子材料产生溶解、溶胀等不良影响；(2)有利于保证在极片压实过程中，胶层不易变形。
相对于所述胶层的总重量(即，将高分子材料、导电材料、无机填料和任选存在的其他助剂的总重量视为100％)，所述无机填料的重量百分比通常为10wt％-60wt％。无机填料含量过小，不足以稳定胶层；含量过大，则会影响胶层的延展性等性能。无机填料的重量百分比优选为15wt％-45wt％。
当无机填料的颗粒粒径过小时，比表面积增大，副反应会增多；过大时，会造成胶层的涂布厚度过大且厚度易不均匀。优选地，胶层中的无机填料的平均粒径D满足100nm≤D≤10μm，更优选为1μm≤D≤6μm。
还优选地，胶层中的无机填料的比表面积(BET)为不大于500m 2/g。无机填料比表面积增大时，副反应会增多影响电池性能；而且无机填料比表面积过大时，需消耗更高比例的粘结剂，会造成胶层与集流体、正极活性材料层之间的粘结力降低，内阻增长率较高。当无机填料的比表面积(BET)为不大于500m 2/g时，可以提供更好的综合效果。
所述无机填料选自金属氧化物、非金属氧化物、金属碳化物、非金属碳化物、无机盐中的至少一种，或上述材料的导电碳包覆改性、导电金属包覆改性或导电聚合物包覆改性的材料中的至少一种。
例如，所述无机填料可以选自氧化镁、氧化铝、二氧化钛、氧化锆、二氧化硅、碳化硅、碳化硼、碳酸钙、硅酸铝、硅酸钙、钛酸钾、硫酸钡、钴酸锂、锰酸锂、镍酸锂、镍锰酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、钛酸锂中的至少一种，或上述材料的导电碳包覆改性、导电金属包覆改性或导电聚合物包覆改性的材料中的至少一种。
尤其是，发明人发现，当胶层用于正极极片时，使用正极电化学活性材料或正极电化学活性材料的导电碳包覆改性、导电金属包覆改性或导电聚合物包覆改性的材料作为无机填料具有特别的优势。这种情况下，无机填料除了上面提到的稳定胶层的作用(阻碍有机溶剂对高分子材料产生溶解、溶胀等不良影响和保证胶层不易变形)之外，进一步地，还可以发挥如下两方面的作用：
(1)改善电池的过充性能：由于电化学活性材料具有嵌脱锂离子的特点，在过充过程中，电化学活性材料会脱锂且脱锂难度越来越大，阻抗不断增加，因此当电流通过时，产热功率增大，胶层的温度增加速度更快，从而造成胶层中的高分子材料体积增大，胶层中导电材料组成的导电网络遭到“破坏”，胶层中的电阻增大，从而可以改善电池的过充安全性能；(2)贡献充放电容量：由于电化学活性材料可以在电池正常工作温度下贡献一定的充放电容量，因此可使得在正 常工作温度下胶层对电池的容量等电化学性能的影响降至最低。
因此，对于正极极片而言，使用正极电化学活性材料或正极电化学活性材料的导电碳包覆改性、导电金属包覆改性或导电聚合物包覆改性的材料作为胶层中的无机填料是最优选的。所述正极电化学活性材料优选是选自钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂、钛酸锂、或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。尤其是经导电碳包覆改性的这些电化学活性材料，例如导电碳包覆改性的钴酸锂、导电碳包覆改性的镍锰钴酸锂、导电碳包覆改性的镍锰铝酸锂、导电碳包覆改性的磷酸铁锂、导电碳包覆改性的磷酸钒锂、导电碳包覆改性的磷酸钴锂、导电碳包覆改性的磷酸锰锂、导电碳包覆改性的磷酸锰铁锂、导电碳包覆改性的硅酸铁锂、导电碳包覆改性的硅酸钒锂、导电碳包覆改性的硅酸钴锂、导电碳包覆改性的硅酸锰锂、导电碳包覆改性的尖晶石型锰酸锂、导电碳包覆改性的尖晶石型镍锰酸锂、导电碳包覆改性的钛酸锂中的至少一种。这些电化学活性材料和导电碳包覆改性的电化学活性材料是锂电池制造中的常用材料，大部分可通过商业途径直接购买获得。其中导电碳的种类可以采用石墨、石墨烯、导电炭黑、碳纳米管等。此外，通过调节导电碳的包覆含量可以调节无机填料的电导率。
在上述材料中，优选为磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂或它们的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种。其原因一是由于磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂等物质本身安全性能较高，在过充时不释氧；其二是相对于钴酸锂、镍锰钴酸锂等材料来说，上述材料在过充时电阻增加更大，使胶层产热较多，从而可以加强改善电池过充安全的效果。
作为本申请的一种进一步改进，当无机填料的电导率σ满足10 -3S/m≤σ≤ 10 2S/m时，会带来额外的好处。发明人发现，无机填料的添加会影响胶层的导电性能，进而可能影响整个极片的导电性。当无机填料的电导率σ满足10 -3S/m≤σ≤10 2S/m时，可以使胶层在电池正常使用温度下的导电性能得以改善。若无机填料的电导率σ过小，则胶层的初始内阻和内阻增长率会很高；σ过高，则导电网络不易被切断，不利于改善过充安全和穿钉安全。
本领域技术人员可以理解：如果某些无机填料的电导率σ不满足10 -3S/m≤σ≤10 2S/m，则可以通过本领域常用的材料修饰或改性手段使得其电导率满足上述要求。
再次，发明人发现，控制高分子材料与导电材料的比例有利于改善胶层的性能。
在本申请的实施方式中，胶层除了高分子材料和无机填料之外，还包含导电材料。
为了在正常的工作条件下，电化学装置可正常地进行电化学反应，胶层中必须包含一定含量的导电材料。导电材料的含量过低，则不利于电化学装置在正常的工作条件下的电化学反应，内阻过大；导电材料的含量过高，则导电网络不易被破坏，从而不利于电化学装置的过充安全性能的改善。
相对于所述胶层的总重量(即，将高分子材料、导电材料、无机填料和任选存在的其他助剂的总重量视为100％)，，所述导电材料的重量百分比为5wt％-25wt％，优选为5wt％-20wt％。
优选地，胶层中高分子材料与导电材料的重量比大于等于2，优选为3至8。
所述导电材料可以选自导电碳基材料、导电金属材料和导电聚合物材料中的至少一种。优选地，导电碳基材料选自导电炭黑、乙炔黑、石墨、石墨烯、碳纳米管、碳纳米纤维中的至少一种；导电金属材料选自Al粉、Ni粉、金粉中的至少一种；导电聚合物材料选自导电聚噻吩、导电聚吡咯、导电聚苯胺中的至少一种。导电材料可单独使用一种或组合使用两种以上。
导电材料通常以粉末或颗粒的形式使用。取决于具体应用环境，其粒径可以是5nm-500nm，例如10nm-300nm、15nm-200nm、15nm-100nm、20nm-400nm、20nm-150nm等等。
本申请的胶层
本申请的胶层可以通过常规方法来形成。例如，通过将高分子材料、导电材料、无机填料和可选的其他助剂溶解在溶剂中并搅拌形成浆料，然后将浆料涂覆到集流体之上，加热烘干即可得到所需胶层。
在本申请的一些优选实施方式中，且本申请的胶层可以基本上由所述高分子材料(包括胶层基体和任选存在的粘结剂)、导电材料和无机填料组成，即不含显著量(例如含量≤3％、≤1％、或≤0.5％)的其他组分。
在本申请的正极极片中，胶层直接粘附在集流体之上，设置于集流体和正极活性材料层之间。所述胶层的厚度H可以根据实际需要进行合理确定。所述胶层的厚度H通常为不大于40μm，优选的为不大于25μm，更优选的为不大于20μm、15μm或10μm。胶层的涂布厚度通常为大于或等于1μm，优选的为大于或等于2μm，更优选为大于或等于3μm。厚度过小，不足以保证胶层改善电池安全性能的效果；过大，会造成电池内阻增大严重，从而影响电池正常工作时的电化学性能。优选地1μm≤H≤20μm，更优选地3μm≤H≤10μm。
优选胶层与集流体之间的结合力优选大于等于10N/m。
通常胶层和正极活性材料层在涂布并烘干之后，不易分离，因此在本申请中，将胶层与正极活性材料层统称为膜片层。因此膜片层与集流体之间的结合力与胶层与集流体之间的结合力相当。
较大的结合力可以保证胶层有效地、可靠地在穿钉等异常情况下包裹集流体以及集流体中产生的金属毛刺。
发明人还发现，本申请中，膜片层的延展率对于极片的穿钉安全性能有一定 影响。
对于常规的锂离子电池的正极活性材料层来说(即不含胶层的膜片层)，其延展率一般不超过1％，无法起到包裹金属毛刺的作用，因此裸露的金属毛刺易于导致电池内短路。而根据本申请的正极极片，由于胶层的引入，膜片层的延展率得到了很大的提高，可以包裹集流体中可能产生的金属毛刺，防止电池内短路的发生，从而大大改善电池的穿钉安全性。
作为本申请的一种进一步改进，所述膜片层的延展率为大于等于30％，优选大于等于80％。较大延展率的好处是：在穿钉等异常情况下，延展率较大的膜片层可以包裹集流体中可能产生的金属毛刺，防止电池内短路的发生，从而大大改善电池的穿钉安全性。
膜片层的延展率可通过改变胶层中高分子材料的种类、相对用量、分子量、交联程度等来进行调整。若增大胶层中的高分子材料的含量，则必然会对膜片层的延展率的提高有益。然而若胶层中的高分子材料的含量过大，则会造成导电材料的含量相对较低，由此造成正常工作时电池的DCR增长较大。因此优选膜片层的延展率大于等于80％且小于等于300％。
集流体
对于集流体的材料，可以使用本领域常用的材料，优选金属集流体，例如不锈钢、铝、铜、钛等金属薄片或金属箔。优选地，所述集流体为含铝多孔集流体(例如多孔铝箔)。由于减少了电芯厚度方向上单位面积内的铝金属含量，在穿钉等异常情况下，多孔铝箔的使用可以降低金属毛刺的产生概率，并进而降低发生剧烈铝热反应的概率，因此可以进一步改善电化学装置的安全性。此外，多孔铝箔的使用还可以改善电解液浸润极片，并进而改善锂离子电池的动力学性能；而胶层则可以覆盖在多孔铝箔的表面，防止上层活性材料层在涂布过程中的漏涂现象。含铝多孔集流体的孔面积占比优选为5％至75％。
另外，考虑到穿钉安全性，集流体的断裂伸长率δ优选为0.8％≤δ≤4％。业已发现，如果集流体的断裂伸长率过大，则被穿刺时金属毛刺较大，不利于改善电池的安全性能；反之，如果集流体的断裂伸长率过小，则在极片压实等加工过程中或电池受到挤压或碰撞时容易出现断裂，降低电池质量或安全性。因此，为了进一步改善安全性，尤其是穿钉安全性，集流体的断裂伸长率δ应该不大于4％且不小于0.8％。金属集流体的断裂伸长率可通过改变金属集流体的纯度、杂质含量和添加剂、坯料生产工艺、轧制速度、热处理工艺等进行调整。
集流体的厚度优选为4μm至16μm。
正极活性材料层
用于本申请正极极片的正极活性材料层可以选用本领域常用的各种常规正极活性材料层，其构成和制备方法是本领域公知的，并无特殊限制。所述正极活性材料层中含有正极活性物质，可以使用本领域技术人员公知的各种用于制备锂离子二次电池正极的正极活性物质，例如该正极活性物质为含锂复合金属氧化物，具体材料例如是LiCoO 2、LiNiO 2、LiMn 2O 4、LiFePO 4、锂镍钴锰氧化物中的一种或几种(如LiNi 0.5Co 0.2Mn 0.3O 2)和锂镍锰氧化物中的一种或几种。
当使用正极电化学活性材料(或其包覆改性材料)作为正极极片的胶层的无机填料时，在胶层中的正极电化学活性材料和在正极活性材料层中所使用的正极活性物质可以相同也可以不同。
电化学装置
本申请还公开了一种电化学装置，该电化学装置包含了根据本申请的正极极片。所述电化学装置可以为电容器、一次电池或二次电池。例如可以为锂离子电容器、锂离子一次电池或锂离子二次电池。除了使用了本申请的正极极片外，这些电化学装置的构造和制备方法本身是公知的。
用于与本申请的正极极片配合使用的负极极片可以选用本领域常用的各种常规负极极片，其构成和制备方法是本领域公知的。例如，负极极片可以包括负极集流体和设置于负极集流体上负极活性材料层，所述负极活性材料层可以包括负极活性材料、粘结剂和导电材料等。负极活性材料例如为诸如石墨(人造石墨或天然石墨)、导电炭黑、碳纤维等的碳质材料，例如Si、Sn、Ge、Bi、Sn、In等金属或半金属材料或其合金，含锂氮化物或含锂氧化物，锂金属或锂铝合金等。
由于使用了本申请的正极极片，所述电化学装置可以具有改善的安全性(如穿钉安全性)和电性能。并且本申请的正极极片容易加工，因此可以降低使用了本申请的正极极片的电化学装置的制造成本。
在本申请的一个具体实施方式中，电化学装置为锂离子电池。图2是锂离子电池5的一实施方式的立体图。图3是图2的分解图。参照图2至图3，锂离子电池5包括壳体51、电极组件52、顶盖组件53以及电解液(未示出)。
电极组件52收容于壳体51内。电极组件52的数量不受限制，可以为一个或多个。电极组件52包括正极极片、负极极片、隔离膜。隔离膜将正极极片和负极极片隔开。电解液注入在壳体51内并浸渍电极组件52，所述电极组件包括例如第一极片、第二极片以及隔离膜。
注意的是图2所示的锂离子电池5为罐型电池，但不限于此，锂离子电池5可以是袋型电池，即壳体51由金属塑膜替代且取消顶盖组件53。
接下来说明本申请又一方面的电池模块。
图4是电池模块4的一实施方式的立体图。
本申请的实施方式提供的电池模块4包括本申请的锂离子电池5。
参照图4，电池模块4包括多个电池5。多个锂离子电池5沿纵向排列。电池模块4可以作为电源或储能装置。电池模块4中的锂离子电池5的数量可以 根据电池模块4的应用和容量进行调节。
接下来说明本申请又一方面的电池包。
图5是电池包1的一实施方式的立体图。图6是图5的分解图。
本申请提供的电池包1包括本申请的一实施方式所述的电池模块4。
具体地，参照图5和图6，电池包1包括上箱体2、下箱体3以及电池模块4。上箱体2和下箱体3组装在一起并形成收容电池模块4的空间。电池模块4置于组装在一起的上箱体2和下箱体3的空间内。电池模块4的输出极从上箱体2和下箱体3的其中之一或二者之间穿出，以向外部供电或从外部充电。电池包1采用的电池模块4的数量和排列可以依据实际需要来确定。
接下来说明本申请又一方面的装置。
图7是锂离子电池作为电源的装置的一实施方式的示意图。
本申请提供的装置包括本申请的一实施方式所述的锂离子电池5，所述锂离子电池5可以用作所述装置的电源。在图7中，采用锂离子电池5的装置为电动汽车。当然不限于此，采用锂离子电池5的装置可以为除电动汽车外的任何电动车辆(例如电动大巴、电动有轨电车、电动自行车、电动摩托车、电动踏板车、电动高尔夫球车、电动卡车)、电动船舶、电动工具、电子设备及储能系统。电动汽车可以为电动纯电动车、混合动力电动车、插电式混合动力电动车。当然，依据实际使用形式，本申请提供的装置可包括本申请所述的电池模块4，当然，本申请提供的装置也可包括本申请的所述的电池包1。
本领域技术人员可以理解：以上提到的本申请的不同实施方式中对于胶层 中组分选择、组分含量和材料理化性能参数的各种限定或优选范围可以任意组合，其组合而得到的各种实施方式仍然在本申请范围内，且视为本说明书公开内容的一部分。
实施例
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合实施例进一步详细描述本申请。但是，应当理解的是，本申请的实施例仅仅是为了解释本申请，并非为了限制本申请，且本申请的实施例并不局限于说明书中给出的实施例。实施例中未注明实验条件采用常规条件，或采用材料供应商或设备供应商推荐的条件。
1、制备方法
1.1正极极片的制备
1)胶层：采用一定配比的胶层基体、可选的粘结剂、导电材料、无机填料，以N-甲基-2-吡咯烷酮(NMP)为溶剂，搅拌均匀后涂布在金属集流体的两个表面上，在85℃下烘干后得胶层。
2)正极活性材料层：然后再将90wt％正极活性材料、5wt％SP和5wt％PVDF，以NMP为溶剂，搅拌均匀后涂布在按照上述方法所制备的集流体的胶层上；在85℃下烘干后得到正极活性材料层。
3)后处理：然后对带有胶层和正极活性材料层的集流体进行冷压，然后切边、裁片、分条，再在85℃真空条件下烘干4小时，焊接极耳，制成满足要求的二次电池正极极片。
在各具体实施例的胶层中使用的主要材料如下：
胶层基体：聚丙烯腈、聚丙烯腈-丙烯酸酯、聚丙烯酸酯；
正极活性材料：NCM811(LiNi 0.8Co 0.1Mn 0.1O 2)；
粘结剂：PVDF(厂家“苏威”，型号5130)；
导电材料(导电剂)：Super-P(瑞士TIMCAL公司，简称SP)；
无机填料：氧化铝、碳包覆改性的磷酸铁锂(简写为LFP/C)，碳包覆改性的钛酸锂(简写为Li 4Ti 5O 12/C)。
以上所用材料均为锂电池工业领域常见和常用材料，可以通过相应的供应商通过商业途径方便地得到。
1.2负极极片的制备
负极极片：将活性物质石墨、导电剂Super-P、增稠剂CMC、粘接剂SBR按质量比96.5:1.0:1.0:1.5加入到溶剂去离子水中混合均匀制成阳极浆料；将阳极浆料涂布负极金属集流体铜箔表面上，并在85℃下烘干，然后进行切边、裁片、分条，再在110℃真空条件下烘干4小时，焊接极耳，制成满足要求的二次电池负极极片。
1.3电解液的配制
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照3∶5∶2体积比进行混合得EC/EMC/DEC混合溶剂，接着将充分干燥的锂盐LiPF 6溶解于混合溶剂中得浓度为1M的溶液，即得电解液。
1.4电池的制备
以12μm的聚丙烯薄膜作为隔离膜，将正极极片、隔离膜和负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间起到隔离的作用，然后卷绕成裸电芯。在75℃下真空烘烤10h，注入(按照上面“电解液的配制”所述配制的)电解液，经过真空封装、静置24h，之后用0.1C的恒定电流充电至4.2V，然后 以4.2V恒压充电至电流下降到0.05C，再以0.1C的恒定电流放电至3.0V，重复2次充放电，最后以0.1C的恒定电流充电至3.8V，即完成二次电池的制备。
2、材料性能的测试
在各实施例和对比例中，除非另有指明，对于材料的物理性能参数均采用本领域的常用公知方法进行测量。
一些具体参数采用以下方法进行测试。
2.1粒径
将材料的粉末样品分散于分散介质(蒸馏水)中，使用马尔文激光粒度仪MS2000，测量5次取平均值，单位μm。
2.2 BET(比表面积)
使用Quadrasorb SI比表面测试仪测试材料的粉末样品的比表面积，测量5次取平均值，单位m 2/g。
2.3胶层与集流体之间的结合力
将含集流体的双面具有膜片层的极片裁切为宽度为2cm，长度15cm的待测样品，将待测样品的一面在25℃、常压条件下，使用3M双面胶均匀贴于不锈钢板上，将待测样品的一端固定在高铁拉力机上，使用高铁拉力机将待测样品的膜片层与集流体剥离，根据拉力和位移的数据图，读取最大拉力，将读取的值(单位N)除以样品的宽度(0.02m)，计算得到结合力(N/m)。
2.4集流体断裂伸长率
在集流体上取2个长度为200mm，宽度为15mm的样片，用万分尺量取样品的厚度h(μm)。然后将样片固定于拉力机(型号AI7000)上，以50mm/min速度进行拉伸。2次测试的算数平均值为测试结果。记录初始长度L0，启动拉力机测试，直至样片断裂，从拉力机上读取断裂时样片的位移L1。。断裂伸长率＝(L1-L0)/L0*100％。
2.5集流体厚度、胶层厚度、膜片层厚度
集流体厚度：采用万分尺测量，测量5处取平均值。
胶层厚度、膜片层厚度：先测量集流体厚度，涂覆胶层后再测量总厚度，以两者之差作为胶层厚度。膜片层厚度采用类似的方法。
2.6涂层开裂状况
在烘干并得到正极活性材料层之后，100m 2极片不出现裂纹定义为不开裂。100m 2极片裂纹出现次数≤3，定义为轻度开裂。100m 2极片裂纹出现次数＞3，定义为严重开裂。
2.7 130℃、5min内于NMP中的溶解度
将高分子材料制成7μm厚胶膜，裁剪成20mm*50mm长条，称重并记为M1；
将胶膜置于NMP(N-甲基吡咯烷酮)溶剂中，130℃下放置5min，取出，100℃下真空烘干；真空烘干后称量重量并记为M2；
则溶解度＝(M1-M2)/M1*100％
本申请中，为方便比较，以PVDF(厂家“苏威”，型号5130)的溶解度作为参比，记为100％，记录其它材料溶解度相对于PVDF溶解度的比值。
2.8膜片层的延展率
取极片并去除集流体：将正极极片从电芯中取出，加入电解液，使极片完全浸泡于电解液中，置于90℃下存储48h以上，然后取出极片，正极极片的膜片层即可从集流体上剥落。
将去除集流体后的膜片层，制成宽度20mm、长度50mm的试样，用万分尺量取样品的厚度h(μm)。然后将试样固定于拉力机(型号AI7000)上，记录初始长度L0。启动拉力机测试，以50mm/min速度进行拉伸，直至试样断裂。从拉力机上读取断裂时试样的位移L1。延展率＝(L1-L0)/L0*100％。
3、电池的性能测试
采用GBT31485-2015《电动汽车用动力蓄电池安全要求及试验方法》对各实施例和对比例的二次电池的安全性进行评估，并记录测试结果。
3.1针刺测试：
将二次电池以1C电流满充至充电截止电压，再恒压充电至电流降至0.05C，停止充电。用
Figure PCTCN2019118843-appb-000001
的耐高温钢针(针尖的圆锥角度为45°)，以25mm/s的速度，从垂直于电池极板的方向贯穿，贯穿位置宜靠近所刺面的几何中心，钢针停留在电池中，观察电池是否有燃烧、爆炸现象。
针对20个电池样品进行测试。
3.2过充测试：
将二次电池以1C电流满充至充电截止电压，再恒压充电至电流降至0.05C，停止充电。然后，以1C电流恒流至充电终止电压的1.5倍或充电1h后停止充电。
针对20个电池样品进行测试。
3.3循环性能测试：
循环次数测试条件为：在25℃下，将二次电池进行1C/1C循环测试，充放电电压范围2.8～4.2V，容量衰减至首次放电比容量的80％时停止测试，并记录循环次数。
3.4直流电阻增长率测试
将二次电池以1C电流满充至充电截止电压，再恒压充电至电流降至0.05C，停止充电，测试电芯直流电阻(4C电流放电10s)。然后将电芯放置于130℃下恒温1h，测试直流电阻，计算直流电阻增长率；然后将电芯放置于130℃下恒温2h，测试直流电阻，计算直流电阻增长率。
3.5 DCR测试
在25℃下，以1C电流将二次电池调整至50％SOC，记录电压U1。然后以4C电流放电30秒，记录电压U2。DCR＝(U1-U2)/4C。
本申请中，为方便比较，以仅含PVDF为高分子材料的电芯的DCR作为参比，记为100％，计算和记录其它电芯的DCR和其比值。
4、性能测试结果
4.0胶层基体材料的溶解度
选择不同的胶层基体材料，按照上述“2.7 130℃、5min内于NMP中的溶解度”中所述方法测量溶解度，结果如下：
130℃、5min内于NMP中的溶解度：
材料 溶解度
PVDF 100％
聚丙烯腈 8％
聚丙烯腈-丙烯酸酯 12％
聚丙烯酸酯 15％
上述结果表明，聚丙烯腈、聚丙烯腈-丙烯酸酯、聚丙烯酸酯均为在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下的油性高分子材料，因此适于作为本申请中的胶层基体材料使用。
4.1胶层的防护效果和对电池性能的影响
为了验证胶层的防护效果，以下面表1-1中所列出的具体材料和用量，按照“1、制备方法”所描述的方法和步骤制备出相应的胶层、正极极片、负极极片和电池，然后按照“3、电池的性能测试”部分规定方法进行测试。为了保证数据准确，每种电池制备4个(用于针刺测试或过充测试的电池制备20个)并独立测试，最终测试结果取平均值，示于表1-2。
其中，常规极片P基本按照“1.1正极极片的制备”所述方法进行制备，但是不设置胶层，即正极活性材料层直接涂覆在集流体上，常规极片N按照“1.2 负极极片的制备”所述方法制备。
表1-1：极片组成
Figure PCTCN2019118843-appb-000002
表1-2：锂离子电池的性能测试结果
Figure PCTCN2019118843-appb-000003
表1-1和表1-2的数据表明：
(1)若采用溶解、溶胀比较大的高分子材料(例如PVDF)作为胶层基体材料，则会产生开裂、电池DCR恶化的问题，而采用聚丙烯腈等溶解、溶胀相对较小的高分子材料作为胶层基体材料，则明显改善了上述问题，且由聚丙烯腈等溶解、溶胀相对较小的高分子材料组成的胶层相对于常规正极极片而言，也进一步明显改善了电池的穿钉安全性能；
(2)胶层中不添加无机填料(LFP/C)的极片，由于胶层会发生变形或被破坏，因而抗穿钉改善效果无法保证；而添加了无机填料的胶层则有效改善了电池的穿钉安全性能。
综合考虑穿钉性能、涂层开裂情况和电池电阻DCR等因素，上述电池中以使用了极片1、2、3的电池3、4、5的性能最为均衡，既具有相对较好的穿钉安全性能，在涂布时也不会造成涂层开裂，另外DCR也可以接受。
4.2胶层中组分含量的影响
为了进一步研究胶层中组分含量的影响，以下面表2-1中所列出的具体材料和用量，按照“1、制备方法”所描述的方法和步骤制备出相应的胶层、正极极片、负极极片和电池，然后按照“3、电池的性能测试”部分规定方法进行测试。为了保证数据准确，每种电池制备4个(用于针刺测试或过充测试的电池制备20个)并独立测试，最终测试结果取平均值，总结于表2-2。
表2-1：极片组成
Figure PCTCN2019118843-appb-000004
表2-2：锂离子电池的性能测试结果
电池 正极 负极 针刺测试(20个电池) 循环寿命(cycle)
电池3 极片1 常规极片N 10个通过 1600
电池3-1 对比极片1-1 常规极片N 5个通过 1880
电池3-2 对比极片1-2 常规极片N 15个通过 1170
电池3-3 对比极片1-3 常规极片N 12个通过 1060
电池3-4 极片1-4 常规极片N 13个通过 1300
电池3-5 极片1-5 常规极片N 14个通过 1200
电池3-6 极片1-6 常规极片N 12个通过 1250
电池3-7 极片1-7 常规极片N 10个通过 1900
电池3-8 极片1-8 常规极片N 9个通过 1890
电池3-9 极片1-9 常规极片N 8个通过 1300
         
表2-1和表2-2的数据表明：(1)无机填料含量过低，则胶层易于变形、稳定性不高，因此电池的安全性能不能得到充分改善；无机填料含量过高，则高分子基体含量会过低，则胶层延展性降低，无法保证胶层正常发挥改善穿钉安全的效果；(2)导电材料对电池的内阻、极化的影响较大，因此会影响电池的循环寿命，导电材料含量越高，则电池的内阻、极化越小，则循环寿命越好。
经实验发现胶层的各组分的适当含量范围如下：
高分子材料的重量百分比为35wt％-75wt％；
导电材料的重量百分比为5wt％-25wt％；且
无机填料的重量百分比为10wt％-60wt％。
只要胶层的各组分含量在以上范围内，就可以实现改善电池的安全性和电性能(如循环性能)的效果。
4.3无机填料种类对电池性能的影响
为了进一步研究胶层中材料选择对极片和电池性能的影响，以下面表3-1中所列出的具体材料和用量，按照“1、制备方法”所描述的方法和步骤制备出相应的胶层、正极极片、负极极片和电池，然后按照“3、电池的性能测试”部分规定方法进行测试。为了保证数据准确，每种电池制备4个(用于针刺测试或过充测试的电池制备20个)并独立测试，最终测试结果取平均值，总结于表3-2。
表3-1：极片组成
Figure PCTCN2019118843-appb-000005
表3-2：锂离子电池的性能测试结果
电池 正极 负极 针刺测试 过充测试
电池3 极片1 常规极片N 10个通过 全部通过
电池3-11 极片1-11 常规极片N 9个通过 全部不通过
电池3-12 极片1-12 常规极片N 10个通过 全部通过
表3-1和表3-2的数据表明，(1)以氧化铝作为无机填料的话，也改善了电池的穿钉安全性能；(2)然而相对于其他材料(例如氧化铝)来说，电化学活性材料能够进一步明显改善电池的过充安全性能。
4.4加入粘结剂对电池性能的影响
为了进一步研究胶层中粘结剂的选择对极片和电池性能的影响，以下面表表4-1中所列出的具体材料和用量，按照“1、制备方法”所描述的方法和步骤制备出相应的胶层、正极极片、负极极片和电池，然后按照“3、电池的性能测 试”部分规定方法进行测试。为了保证数据准确，每种电池制备4个(用于针刺测试或过充测试的电池制备20个)并独立测试，最终测试结果取平均值，总结于表4-2。
表4-1和表4-2的数据表明，当胶层中添加了粘结剂PVDF之后，电池的穿钉安全性能得到了进一步改善，尤其是PVDF的含量在15wt％以上的时候；然而由于PVDF在NMP中的溶解溶胀较大，因此会恶化电池DCR并在聚丙烯腈的含量过小时带来涂层开裂问题。
本领域技术人员可以理解：以上仅以锂电池为例示出了本申请极片的应用实例，但是本申请的极片同样可以应用于其它类型的电池或电化学装置，而仍然可以获得本申请的良好技术效果。
根据上述说明书的揭示和教导，本申请所属领域的技术人员还可以对上述实施方式进行适当的变更和修改。因此，本申请并不局限于上面揭示和描述的具体实施方式，对本申请的一些修改和变更也应当落入本申请的权利要求的保护范围内。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本申请构成任何限制。
表4-1：极片组成
Figure PCTCN2019118843-appb-000006
1，2:相对于胶层总重量的重量百分百；3:相对于高分子材料总重量(即胶层基体+粘结剂)的
表4-2：锂离子电池的性能测试结果
Figure PCTCN2019118843-appb-000007

Claims (13)

  1. 一种正极极片，包括集流体、正极活性材料层和设置于所述集流体与所述正极活性材料层之间的胶层，
    所述胶层包含高分子材料、导电材料和无机填料，其中所述高分子材料包含胶层基体，所述胶层基体为在130℃、5min内于NMP中的溶解度为相同条件下PVDF的溶解度的30％以下的油性高分子材料。
  2. 根据权利要求1所述的正极极片，其中在所述胶层中，相对于所述胶层的总重量，
    所述高分子材料的重量百分比为35wt％-75wt％，
    所述导电材料的重量百分比为5wt％-25wt％，且
    所述无机填料的重量百分比为10wt％-60wt％，
    优选地，所述高分子材料还包含粘结剂，相对于所述胶层的总重量，所述胶层基体的重量百分比为大于等于20wt％。
  3. 根据权利要求1所述的正极极片，其中在所述胶层中，所述高分子材料还包含任选存在的粘结剂，且基于所述高分子材料的重量为100％，
    所述胶层基体的重量百分比为30wt％-100wt％，且
    所述粘结剂的重量百分比为0wt％-70wt％。
  4. 根据权利要求1-3任一项所述的正极极片，其中所述胶层基体选自聚丙烯腈、聚丙烯酸、聚丙烯酸酯、聚丙烯酸-丙烯酸酯、聚丙烯腈-丙烯酸、聚丙烯腈-丙烯酸酯中的至少一种。
  5. 根据权利要求1-3任一项所述的正极极片，其中所述粘结剂优选聚偏氟乙烯(PVDF)、羧酸改性的PVDF、丙烯酸改性的PVDF、聚偏氯乙烯(PVDC)、羧酸改性的PVDC、丙烯酸改性的PVDC、PVDF共聚物、PVDC共聚物中的至少一种。
  6. 根据权利要求1-3任一项所述的正极极片，其中所述导电材料选自导电碳基材料、导电金属材料和导电聚合物材料中的至少一种，优选地，
    所述导电碳基材料选自导电炭黑、乙炔黑、石墨、石墨烯、碳纳米管、碳纳米纤维中的至少一种；
    所述导电金属材料选自Al粉、Ni粉、金粉中的至少一种；
    所述导电聚合物材料选自导电聚噻吩、导电聚吡咯、导电聚苯胺中的至少一种。
  7. 根据权利要求1-3任一项所述的正极极片，其中
    所述无机填料选自金属氧化物、非金属氧化物、金属碳化物、非金属碳化物、无机盐中的至少一种，或上述材料的导电碳包覆改性、导电金属包覆改性或导电聚合物包覆改性的材料中的至少一种；
    优选地，所述胶层中的无机填料为氧化镁、氧化铝、二氧化钛、氧化锆、二氧化硅、碳化硅、碳化硼、碳酸钙、硅酸铝、硅酸钙、钛酸钾、硫酸钡、钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂、钛酸锂、或上述材料的导电碳包覆改性材料、导电金属包覆改性材料或导电聚合物包覆改性材料中的至少一种；和/或
    优选地，所述无机填料的平均粒径D为100nm≤D≤10μm；和/或
    优选地，所述无机填料的比表面积(BET)为不大于500m 2/g。
  8. 根据权利要求2或3所述的正极极片，其中在所述胶层中，相对于所述胶层的总重量，
    所述高分子材料的重量百分比为50wt％-75wt％，
    所述导电材料的重量百分比为5wt％-20wt％，且
    所述无机填料的重量百分比为15wt％-45wt％。
  9. 根据权利要求1-8任一项所述的正极极片，其中所述胶层的厚度H为 1μm≤H≤20μm；所述胶层基本上由所述高分子材料、所述导电材料和所述无机填料组成。
  10. 一种电化学装置，包括根据权利要求1至9任一项所述的正极极片，所述电化学装置为电容器、一次电池或二次电池，优选为锂离子电池。
  11. 一种电池模块，其特征在于，包括根据权利要求10所描述的电池。
  12. 一种电池包，其特征在于，包括根据权利要求11所述的电池模块。
  13. 一种装置，其特征在于，包括根据权利要求10所描述的电池，所述电池作为所述装置的电源；优选地，所述装置包括电动车辆、混合动力电动车辆、插电式混合动力电动车辆、电动自行车、电动踏板车、电动高尔夫球车、电动卡车、电动船舶、储能系统。
PCT/CN2019/118843 2018-11-16 2019-11-15 一种正极极片及电化学装置 WO2020098791A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201811366437.1A CN111200101B (zh) 2018-11-16 2018-11-16 一种正极极片及电化学装置
CN201811366437.1 2018-11-16

Publications (1)

Publication Number Publication Date
WO2020098791A1 true WO2020098791A1 (zh) 2020-05-22

Family

ID=66857771

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2019/118843 WO2020098791A1 (zh) 2018-11-16 2019-11-15 一种正极极片及电化学装置

Country Status (4)

Country Link
US (1) US11211610B2 (zh)
EP (1) EP3654427A1 (zh)
CN (1) CN111200101B (zh)
WO (1) WO2020098791A1 (zh)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114512678A (zh) * 2020-11-16 2022-05-17 Oppo广东移动通信有限公司 集流体、电池及电子设备
CN114156450A (zh) * 2021-11-29 2022-03-08 珠海冠宇电池股份有限公司 极片及电化学装置
CN114300649B (zh) * 2021-12-29 2022-12-06 广东国光电子有限公司 一种安全涂层、正极极片与应用
CN114744206A (zh) * 2022-03-29 2022-07-12 佛山市中技烯米新材料有限公司 一种高安全性的三元锂电池集流体、电极、锂电池
CN116799151A (zh) * 2022-03-31 2023-09-22 宁德时代新能源科技股份有限公司 正极极片、二次电池及用电装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101232104A (zh) * 2007-01-22 2008-07-30 万向集团公司 磷酸铁锂动力聚合物锂离子电池的制造方法
US20120225199A1 (en) * 2010-02-05 2012-09-06 International Battery, Inc. Current collector coating for li-ion battery cells using aqueous binder
CN102832392A (zh) * 2012-06-27 2012-12-19 长沙业翔能源科技有限公司 一种集流体覆碳铝箔及其制备方法
CN104157880A (zh) * 2014-08-29 2014-11-19 合肥国轩高科动力能源股份公司 一种导电金属陶瓷修饰锂离子电池集流体的方法
CN106784617A (zh) * 2016-12-15 2017-05-31 宁德时代新能源科技股份有限公司 一种锂离子电池正极极片，其制备方法及使用该极片的电池
CN106935901A (zh) * 2015-12-31 2017-07-07 东莞新能源科技有限公司 锂离子电池及其阴极极片

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102035039A (zh) * 2009-09-29 2011-04-27 上海比亚迪有限公司 一种高安全性能锂离子电池
CN102176360B (zh) * 2011-02-22 2012-10-10 深圳市长园维安电子有限公司 Ptc热敏电阻及其应用的基材及其制造方法
TWI550655B (zh) * 2012-12-24 2016-09-21 財團法人工業技術研究院 鋰離子電池及其電極結構
JP6416237B2 (ja) * 2014-04-04 2018-10-31 エルジー・ケム・リミテッド 寿命性能が向上した二次電池
CN103956499B (zh) * 2014-04-15 2016-02-10 洛阳月星新能源科技有限公司 一种用于锂离子电池中正极集流体的安全涂层制备方法
CN104409681A (zh) * 2014-11-19 2015-03-11 上海航天电源技术有限责任公司 一种含ptc涂层的锂离子电池极片的制备方法
US10944126B2 (en) 2014-12-08 2021-03-09 Showa Denko Materials Co., Ltd. Positive electrode for lithium ion secondary battery, and lithium ion secondary battery using the same
KR20180041683A (ko) * 2015-08-31 2018-04-24 니폰 제온 가부시키가이샤 비수계 이차 전지 기능층용 조성물, 비수계 이차 전지용 기능층, 및 비수계 이차 전지
JP6798505B2 (ja) * 2015-12-28 2020-12-09 日本ゼオン株式会社 リチウムイオン二次電池用感熱層
CN106220779B (zh) * 2016-08-17 2018-08-31 四川茵地乐科技有限公司 丙烯腈共聚物粘合剂及其在锂离子电池中的应用
JP6579386B2 (ja) * 2016-11-24 2019-09-25 トヨタ自動車株式会社 二次電池の製造方法
CN109755463B (zh) 2017-11-08 2020-12-29 宁德时代新能源科技股份有限公司 一种电极极片、电化学装置及安全涂层

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101232104A (zh) * 2007-01-22 2008-07-30 万向集团公司 磷酸铁锂动力聚合物锂离子电池的制造方法
US20120225199A1 (en) * 2010-02-05 2012-09-06 International Battery, Inc. Current collector coating for li-ion battery cells using aqueous binder
CN102832392A (zh) * 2012-06-27 2012-12-19 长沙业翔能源科技有限公司 一种集流体覆碳铝箔及其制备方法
CN104157880A (zh) * 2014-08-29 2014-11-19 合肥国轩高科动力能源股份公司 一种导电金属陶瓷修饰锂离子电池集流体的方法
CN106935901A (zh) * 2015-12-31 2017-07-07 东莞新能源科技有限公司 锂离子电池及其阴极极片
CN106784617A (zh) * 2016-12-15 2017-05-31 宁德时代新能源科技股份有限公司 一种锂离子电池正极极片，其制备方法及使用该极片的电池

Also Published As

Publication number Publication date
EP3654427A1 (en) 2020-05-20
US20200161659A1 (en) 2020-05-21
CN111200101B (zh) 2021-02-09
CN111200101A (zh) 2020-05-26
US11211610B2 (en) 2021-12-28

Similar Documents

Publication Publication Date Title
WO2020098671A1 (zh) 一种正极极片及电化学装置
WO2020098765A1 (zh) 一种正极极片及电化学装置
WO2020098787A1 (zh) 一种正极极片及电化学装置
WO2020098769A1 (zh) 一种正极极片及电化学装置
WO2020098768A1 (zh) 一种电池
CN111200109B (zh) 一种电池
WO2020098792A1 (zh) 一种正极极片及电化学装置
WO2020098791A1 (zh) 一种正极极片及电化学装置
CN111200132B (zh) 一种电池
WO2020098797A1 (zh) 一种正极极片及电化学装置
WO2020098789A1 (zh) 一种电化学装置
WO2020098784A1 (zh) 一种电池
WO2020098788A1 (zh) 一种正极极片及电化学装置
WO2020098742A1 (zh) 一种电池
CN111200104B (zh) 一种电池
CN111200103B (zh) 一种电池
WO2020098770A1 (zh) 一种正极极片及电化学装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19884222

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19884222

Country of ref document: EP

Kind code of ref document: A1