WO2024040572A1 - 用于正极极片的水性粘接剂以及由其制备的正极极片 - Google Patents

用于正极极片的水性粘接剂以及由其制备的正极极片 Download PDF

Info

Publication number
WO2024040572A1
WO2024040572A1 PCT/CN2022/115119 CN2022115119W WO2024040572A1 WO 2024040572 A1 WO2024040572 A1 WO 2024040572A1 CN 2022115119 W CN2022115119 W CN 2022115119W WO 2024040572 A1 WO2024040572 A1 WO 2024040572A1
Authority
WO
WIPO (PCT)
Prior art keywords
meth
optionally
weight
lithium
positive electrode
Prior art date
Application number
PCT/CN2022/115119
Other languages
English (en)
French (fr)
Inventor
李�诚
刘会会
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
Priority to PCT/CN2022/115119 priority Critical patent/WO2024040572A1/zh
Publication of WO2024040572A1 publication Critical patent/WO2024040572A1/zh

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/04—Acids; Metal salts or ammonium salts thereof
    • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
    • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/42—Nitriles
    • C08F220/44—Acrylonitrile
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/52—Amides or imides
    • C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
    • C08F220/56—Acrylamide; Methacrylamide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to a water-based adhesive used for positive electrode sheets, and also relates to a water-based slurry for preparing positive electrode sheets containing the water-based adhesive, a positive electrode sheet prepared from the water-based slurry, A secondary battery including the positive electrode plate, a battery pack including the secondary battery, and an electrical device.
  • Secondary batteries have become the most popular energy storage system due to their low cost, long life, and good safety. They are now widely used in pure electric vehicles, hybrid electric vehicles, smart grids and other fields. Secondary batteries are mainly composed of positive electrode sheets, negative electrode sheets, isolation films and electrolytes.
  • the preparation of battery electrode sheets (such as positive electrode sheets) requires the use of adhesive materials to firmly bind the active materials of the electrode sheets to conductive agents and other additives. Glued together. Since the traditionally used oil-based adhesives are becoming less and less popular due to factors such as environmental protection and safety, water-based adhesives are being continuously developed in the field for the preparation of electrode pole pieces.
  • the most commonly used water-based adhesive at present is polyacrylic acid (PAA) adhesive.
  • PAA polyacrylic acid
  • This application was made in view of the above problems, and its purpose is to provide an aqueous adhesive used in preparing secondary battery positive electrode sheets and an aqueous slurry containing the same, so as to solve the problem of easy gelation in the process of preparing secondary batteries. , technical problems that the pole piece is easy to crack and has poor brittleness.
  • the first aspect of the present application provides a water-based adhesive, which contains at least one terpolymer, the terpolymer is derived from (meth)acrylic acid, (meth)acrylic acid C 1 - C 20 alkyl esters and (meth)acrylamide, or derived from (meth)acrylonitrile, C 1 -C 20 alkyl (meth)acrylate and (meth)acrylamide, wherein the terpolymer
  • the glass transition temperature Tg of the material is -20°C to 40°C, optionally 0°C to 20°C.
  • the water-based adhesive of the present application can solve the problem that the cathode aqueous slurry prepared therefrom is prone to gelling, so that the aqueous slurry can still have good properties after being left standing for a long time.
  • the fluidity of the aqueous slurry significantly extends the processing time and reduces the difficulty of use.
  • the inventor believes that the terpolymer contained in the water-based adhesive of the present application has copolymerized part of the ester groups in the main chain, so that it has a lower glass transition temperature and is therefore less brittle. chemical while maintaining the strong bonding properties of acrylic adhesives.
  • Nitrile/carboxyl groups have abundant polar groups in the copolymer.
  • -CN is located in the main chain segment of the molecular chain. Due to the dipolar interaction between the -CN group and the electronegativity of the matrix, it has strong adhesion. Attachment.
  • the -COOH group can form a strong hydrogen bond with the -OH group in the oxide layer on the surface of the Al foil to ensure that the active material is firmly attached to the current collector, thereby improving the adhesion of the pole piece and avoiding the pole piece from being Processing abnormalities such as peeling and powder loss may occur during coating or cold pressing.
  • Amide groups can increase adhesion.
  • the weight average molecular weight Mw of the terpolymer is 40,0000-110,0000g/mol, optionally 40,0000-80,0000g/mol, further optionally 45,0000 -60,0000g/mol.
  • the weight ratio of each monomer unit is: (meth)acrylic acid or (meth)acrylonitrile is 50-70%, (meth)acrylic acid C 1 - C 20 alkyl ester is 15-35%, and (meth)acrylamide is 15-35%; optionally, the weight ratio of each monomer unit is: (meth)acrylic acid or (meth)acrylonitrile is 50-60%, C 1 -C 20 alkyl (meth)acrylate 20-30%, and (meth)acrylamide 20-30%.
  • the terpolymer may have the structure of the following general formula (I) or (II):
  • R 1 are the same as or different from each other and are independently H or methyl
  • R 2 is C 1 -C 20 alkyl, optionally C 1 -C 8 alkyl, further optionally methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-octyl, isooctyl,
  • x, y and z are independently integers selected from 100-10000, optionally 500-5000.
  • the C 1 -C 20 alkyl (meth)acrylate is selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate ester, butyl methacrylate, isooctyl methacrylate or combinations thereof.
  • the second aspect of the present application provides an aqueous slurry for preparing positive electrode sheets.
  • the aqueous slurry includes a positive active material, a conductive agent and the aqueous binder described above, and optionally water and a dispersant. , wherein the proportion of the aqueous binder is 0.4-3% by weight, optionally 1.5-2.5% by weight, further optionally 2-2.3% by weight, based on the positive electrode active material, conductive agent and aqueous binder The total weight of the adhesive.
  • the aqueous slurry used to prepare the positive electrode sheet of the present application can effectively suppress the tendency of gelation, improve the adhesive force, and improve the brittleness and electrical performance of the positive electrode sheet prepared by containing the aqueous binder as defined above. , such as cyclic DC resistance (DCR). It has been found that the fluidity (ie, gel resistance) of the aqueous slurry is optimized by including the aqueous binder within a specific proportion range.
  • DCR cyclic DC resistance
  • the weight ratio of the positive active material, conductive agent and aqueous binder is 92-96:1-5:0.5-3, optionally 93-95:3-5:1.5-2.5 , based on the total weight of the cathode active material, conductive agent and aqueous binder.
  • the positive active material is selected from the group consisting of lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and lithium nickel manganese oxide. , one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, optionally lithium iron phosphate.
  • the conductive agent is selected from one or more types of conductive carbon black, superconducting carbon black, conductive graphite, acetylene black, Ketjen black, graphene, and carbon nanotubes.
  • the aqueous slurry further contains 0.4-3 wt% plasticizer, optionally 0.8-2 wt%, further optionally 1.5-1.8 wt%, based on the cathode active material , the total weight of conductive agent and water-based adhesive.
  • the plasticizer is selected from one or more types of polyethylene glycol (PEG), ethylene carbonate (EC), glycerol, etc., optionally ethylene carbonate. It has been found that by adding a specific content of small molecule plasticizer, the brittleness of the positive electrode piece prepared therefrom can be significantly reduced and the appearance of the electrode piece can be improved.
  • the aqueous slurry further contains 0.5-3% by weight of an alkaline additive, optionally 1.2-2.5% by weight, further optionally 1.8-2.3% by weight, based on the cathode active material , the total weight of conductive agent and water-based adhesive.
  • the alkaline additive is selected from alkali metal hydroxides, alkali metal carbonates, alkali metal phosphates and alkali metal carboxylates, optionally lithium hydroxides, carbonates, phosphates and carboxylates , further optionally LiOH and Li 2 CO 3 . It has been found that by adding specific levels of alkaline additives, in particular LiOH and Li2CO3 , the gram capacity of the prepared secondary battery can be significantly increased.
  • the aqueous slurry has a solids content of 30-75% by weight, optionally 45-65% by weight.
  • the dispersant is selected from the group consisting of polyamide dispersants, poly(meth)acrylate dispersants, polycarboxylate dispersants, sulfonate dispersants, and silicate dispersants. , phosphate dispersants, polyethylene imine dispersants, amino-containing polymers and their amine salt dispersants.
  • the aqueous slurry exists in the form of an aqueous dispersion, or in the form of a product obtained by drying the aqueous dispersion.
  • a third aspect of the present application provides a positive electrode sheet prepared by using an aqueous slurry selected from the second aspect of the present application.
  • a fourth aspect of the present application provides a secondary battery including a positive electrode plate selected from the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack including the secondary battery selected from the fourth aspect of the present application.
  • a sixth aspect of the present application provides an electrical device, which includes a secondary battery selected from the fourth aspect of the present application or a battery pack of the fifth aspect of the present application.
  • Figure 1 is a schematic diagram of a lithium ion secondary battery in one embodiment of the present application.
  • FIG. 2 is an exploded view of the lithium ion secondary battery in one embodiment of the present application shown in FIG. 1 .
  • Figure 3 is a schematic diagram of a battery pack in an embodiment of the present application.
  • FIG. 4 is an exploded view of the battery pack in one embodiment of the present application shown in FIG. 3 .
  • Figure 5 is a schematic diagram of a device in which a battery pack is used as a power source in an embodiment of the present application.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range.
  • each individually disclosed point or single value may itself serve as a lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • the acid and ferrous iron ions will combine with each other (the ferrous ions are not actually released, and there will be a certain amount of ferrous ions on the surface of the crystal lattice). ).
  • One ferrous ion forms an ionic bond with two carboxylate groups, forming a cross-link.
  • the high density of ionic bonds causes the water-based slurry to have no fluidity and form a gel, which in turn leads to a series of problems such as gelation, coating cracking, and hard and brittle pole pieces during processing. And in aqueous slurries, this combination will affect the concentration of ferrous iron ions and lithium ions, resulting in a lower gram capacity than in oil-based systems.
  • the first aspect of the application provides a water-based adhesive, which includes at least one terpolymer, the terpolymer is derived from (meth)acrylic acid, (meth)acrylic acid C 1 -C 20 Alkyl esters and (meth)acrylamide, or derived from (meth)acrylonitrile, C 1 -C 20 alkyl (meth)acrylate and (meth)acrylamide, wherein the terpolymer
  • the glass transition temperature Tg is -20°C to 40°C, optionally 0°C to 20°C.
  • the terpolymer can be obtained by free radical polymerization of three monomers, for example, by first adding a part of the initiator into the organic solvent; then adding the corresponding three monomers and possible chain transfer agents in sequence; and then adding Polymerize at an elevated temperature (such as 60-100°C) for 2-24 hours, during which the remaining initiator can be added to the solution; after the polymerization is completed, the terpolymer can be obtained by precipitation, centrifugation and vacuum drying. .
  • the terpolymer can also be end-capped by specific groups, and the final terpolymer can additionally contain a small amount of end-capping groups and a small amount of chain transfer agent residual groups; however, since its content is very Low, it has no substantial impact on the terpolymer, so it is not specifically limited in this article.
  • the terpolymer may have the structure of the following general formula (I) or (II):
  • R 1 are the same as or different from each other and are independently H or methyl
  • R 2 is C 1 -C 20 alkyl, optionally C 1 -C 8 alkyl, further optionally methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-octyl, isooctyl,
  • x, y and z are independently integers selected from 100-10000, optionally 500-5000. In some embodiments, x is an integer selected from 3000-5000, y is an integer selected from 800-1500, and z is an integer selected from 800-1500.
  • the structure of the above general formula (I) or (II) is not intended to limit the terpolymer of this application to (meth)acrylic acid, (meth)acrylic acid C 1 -C 20 alkyl ester and (meth)acrylamide, or alternating block copolymers of (meth)acrylonitrile, C 1 -C 20 alkyl (meth)acrylate, and (meth)acrylamide, indicating instead that each Type and quantity of single units. It is understood that the above structure also includes other possible block copolymers and random copolymers of the above-mentioned monomer units.
  • the water-based adhesive of the present application may also contain a mixture of terpolymers having the structure of the above general formula (I) or (II).
  • x, y and z are selected such that the molecular weight of the final copolymer satisfies the defined ranges stated above.
  • the * sign corresponds to the end group of the terpolymer. As mentioned above, its content is very low and has no substantial effect on the terpolymer.
  • the weight ratio of each monomer unit is: (meth)acrylic acid or (meth)acrylonitrile is 50-70%, (meth)acrylic acid C 1 - C 20 alkyl ester is 15-35%, and (meth)acrylamide is 15-35%; optionally, the weight ratio of each monomer unit is: (meth)acrylic acid or (meth)acrylonitrile is 50-60%, C 1 -C 20 alkyl (meth)acrylate 20-30%, and (meth)acrylamide 20-30%.
  • the corresponding proportions in the terpolymer can be adjusted by adjusting the addition amounts of the three monomers.
  • the C 1 -C 20 alkyl (meth)acrylate is selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate ester, butyl methacrylate, isooctyl methacrylate or combinations thereof.
  • the terpolymer can be a block copolymer or a random copolymer, and its weight average molecular weight Mw can be 40,0000-110,0000g/mol, optionally 40,0000-80,0000g/mol, further Optionally 45,0000-60,0000g/mol.
  • Mw weight average molecular weight
  • the terpolymer has a glass transition temperature Tg of -20°C to 40°C, optionally 0°C to 20°C.
  • Tg glass transition temperature
  • the lower Tg makes the terpolymer have lower viscosity, which helps it to still have higher fluidity after standing for a certain period of time.
  • the Tg can be obtained through the following test methods: 1.
  • Sample preparation Punch the film-like sample into a small disc with a diameter of 6mm, weigh 1 to 3 mg, put it into an Al crucible and flatten it, turn the crucible lid upside down, and obtain a solid sample. Weigh 1 ⁇ 3mg and cover the crucible; 2. Parameter settings: nitrogen atmosphere, purge gas 50mL/min, protective gas 100mL/min; 3. Temperature rise program: 10°C/min, 35°C ⁇ 300°C, 300 Keep at °C for 3 minutes; 10°C/min, 300°C ⁇ 35°C, keep at 35°C for 3min; 10°C/min, 35°C ⁇ 300°C, end. The instrument used was a Discovery 250 differential scanning calorimeter.
  • the water-based adhesive of the present application may optionally contain other additives, such as solvents, dispersants, film-forming aids, etc.
  • the aqueous adhesive is simply the terpolymer described above.
  • a second aspect of the present application provides an aqueous slurry for preparing a positive electrode sheet, which includes a positive active material, a conductive agent and the aqueous binder described above, and optionally water and a dispersant, wherein the The proportion of the aqueous binder is 0.4-3% by weight, optionally 1.5-2.5% by weight, further optionally 2-2.3% by weight, based on the positive electrode active material, conductive agent and aqueous binder Total weight.
  • the aqueous slurry used in the present application for preparing positive electrode sheets can effectively suppress the tendency to gel, improve the adhesive force, and improve the brittleness of the positive electrode sheets prepared therefrom. and electrical properties such as DC Cycling Resistance (DCR). It has been found that by further selecting the aqueous binder within a specific proportion range, the fluidity (ie, anti-gel ability) of the aqueous slurry can be optimized. When the content of the water-based binder in the pole piece is too low, sufficient bonding effect cannot be achieved, and a sufficient amount of conductive agent and positive active material cannot be bonded together.
  • DCR DC Cycling Resistance
  • the adhesive force of the pole piece is small, resulting in extremely The tablets may be demoulded during processing or the active material particles may run into the negative electrode during the long cycle of the battery, causing great safety hazards.
  • the active material coating will be too thick, hindering the transmission of lithium ions in the active material, making it difficult for lithium ions to be released or embedded, resulting in the diaphragm resistance of the pole piece. large, causing the battery impedance to increase.
  • too much binder will not only occupy the load capacity of the main material, reducing the energy density of the battery, but also cause the pole pieces to absorb liquid and expand, causing the DC impedance of the battery to increase.
  • the rebound of the pole piece during the circulation process can be effectively maintained, the appropriate liquid absorption capacity can be maintained, and the growth of DC impedance during long-term circulation can be suppressed.
  • the weight ratio of the positive active material, the conductive agent and the aqueous binder is 92-96:1-5:0.5-3, optionally 93-95:3 -5: 1.5-2.5.
  • the weight ratio of the positive electrode active material, the conductive agent and the aqueous binder can be adjusted by changing the addition amount of the starting materials.
  • the positive active material is selected from lithium iron phosphate, lithium manganese phosphate, lithium cobalt phosphate, lithium iron manganese phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide , one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, optionally lithium iron phosphate.
  • the conductive agent is selected from one or more types of conductive carbon black, superconducting carbon black, conductive graphite, acetylene black, Ketjen black, graphene, and carbon nanotubes.
  • the aqueous slurry further contains 0.4-3 wt% plasticizer, optionally 0.8-2 wt%, further optionally 1.5-1.8 wt%, based on the cathode active material , the total weight of conductive agent and water-based adhesive.
  • the plasticizer may be selected from one or more types of polyethylene glycol (PEG), ethylene carbonate (EC), glycerol, etc., optionally ethylene carbonate. It has been found that by adding a specific content of small molecule plasticizer, the brittleness of the positive electrode piece prepared therefrom can be significantly reduced and the appearance of the electrode piece can be improved.
  • Acrylonitrile or acrylic copolymers naturally have hard and brittle weaknesses, which causes the inner ring of the bare battery core to break and leak metal during hot pressing, and causes the electrolyte to continuously corrode the aluminum foil, thereby affecting the electrical performance.
  • a common method is to copolymerize some esters or ethers in the copolymer, but this method is not effective in solving the flexibility of the copolymer.
  • the grafting of esters will also cause the copolymer to swell too much, causing the battery core to absorb liquid and expand, worsening the DCR of the battery core, and thus affecting the electrical performance.
  • the inventor found that by adding small molecule plasticizers such as polyethylene glycol (PEG), ethylene carbonate (EC), glycerol, etc., the strong intermolecular force (hydrogen key), which can effectively improve the brittleness of the pole pieces obtained therefrom.
  • PEG polyethylene glycol
  • EC ethylene carbonate
  • glycerol glycerol
  • the strong intermolecular force hydrogen key
  • the small molecule plasticizer is added in too much amount, unreacted molecules (such as EC) will easily crystallize during the pole piece manufacturing process, thereby affecting the performance of the battery core. Therefore, the content of the small molecule plasticizer in the aqueous slurry should be controlled within the appropriate range as mentioned above.
  • the aqueous slurry further contains 0.5-3% by weight of an alkaline additive, optionally 1.2-2.5% by weight, further optionally 1.8-2.3% by weight, based on the cathode active material , the total weight of conductive agent and water-based adhesive.
  • the alkaline additive is selected from alkali metal hydroxides, alkali metal carbonates, alkali metal phosphates and alkali metal carboxylates, optionally lithium hydroxides, carbonates, phosphates and carboxylates , further optionally LiOH and Li 2 CO 3 . It has been found that by adding specific levels of alkaline additives, in particular LiOH and Li2CO3 , the gram capacity of the prepared secondary battery can be significantly increased.
  • the pole piece composition of the aqueous system will affect the gram capacity of the positive electrode active material such as lithium iron phosphate.
  • the main reason is that lithium iron phosphate materials will dissociate into divalent ferrous ions and lithium ions in water. , causing part of the gram capacity to be unable to be exerted due to the deactivation of lithium ions.
  • alkaline additives such as LiOH and Li 2 CO 3
  • the pH of the aqueous slurry can be adjusted to inhibit the hydrolysis and dissolution of iron ions, which can effectively reduce the deactivation of lithium ions.
  • the aqueous slurry has a solids content of 30-75% by weight, optionally 45-65% by weight.
  • the composition may also contain a small amount of organic solvents, such as ethanol, acetone, N,N-dimethylpyrrolidone, etc., but the content should be no more than 5%, optionally less than 1%.
  • the aqueous slurry may also include a certain amount of dispersant, such as 0.5-5% by weight, optionally 1-3% by weight, based on the cathode active material, conductive agent and aqueous binder of total weight.
  • the dispersant is selected from polyamide dispersants, poly(meth)acrylate dispersants, polycarboxylate dispersants, sulfonate dispersants, silicate dispersants, and phosphate dispersants. , polyethylene imine dispersants, amino-containing polymers and their amine salt dispersants.
  • the aqueous slurry may exist in the form of an aqueous dispersion, or in the form of a product obtained by drying the aqueous dispersion.
  • the aqueous slurry can be formed by adding the positive electrode active material, conductive agent and aqueous binder to deionized water in a specific weight ratio to form a slurry, optionally adding a certain amount of dispersant and stirring evenly, and then passing it through Ionized water adjusts its solid content to a predetermined range.
  • the resulting aqueous slurry can be coated on the positive electrode current collector by blade coating, roller coating or spraying, and then dried in an oven at elevated temperatures to remove water and optionally organic solvents to obtain a dry form.
  • Positive active material layer The aqueous slurry of the present invention also contains this layered composition in dry form, which may contain a certain amount of residual water.
  • a third aspect of the present application provides a positive electrode sheet prepared by using an aqueous slurry selected from the second aspect of the present application.
  • a fourth aspect of the present application provides a secondary battery including a positive electrode plate selected from the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack including the secondary battery selected from the fourth aspect of the present application.
  • a sixth aspect of the present application provides an electrical device, which includes a secondary battery selected from the fourth aspect of the present application or a battery pack of the fifth aspect of the present application.
  • each component of the secondary battery of the present application can be selected from a wide range.
  • the secondary battery is specifically a lithium ion secondary battery.
  • the battery cells of the lithium ion secondary battery will be described in detail below.
  • a lithium-ion secondary battery typically includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the electrolyte includes electrolyte salts and solvents.
  • the electrolyte salt can be a commonly used electrolyte salt in lithium ion secondary batteries, such as lithium salt, including the above-mentioned lithium salt as a high thermal stability salt, a lithium salt as a low resistance additive, or lithium that inhibits aluminum foil corrosion. Salt.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide (LiFSI), bistrifluoromethanesulfonyl Lithium imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorodioxalate phosphate (LiDFOP), fluorosulfonic acid Lithium (LiSO 3 F), difluorodioxalate (NDFOP), Li 2 F(SO 2 N) 2 SO 2 F, KFSI, CsFSI, Ba(FSI) 2 and LiFSO 2 NSO 2 CH 2 CH 2 CH 2 CH 2
  • the solvent is a non-aqueous solvent.
  • the solvent may include one or more of chain carbonate, cyclic carbonate, and carboxylic acid ester.
  • the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), Dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate Ester (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB) , one of ethyl
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and battery low-temperature performance. additives, etc.
  • the additive is selected from the group consisting of unsaturated bond-containing cyclic carbonate compounds, halogen-substituted cyclic carbonate compounds, sulfate compounds, sulfite compounds, sultone compounds, disulfonic acid compounds, nitrile compounds, aromatic compounds At least one of a compound, an isocyanate compound, a phosphazene compound, a cyclic acid anhydride compound, a phosphite compound, a phosphate compound, a borate compound, and a carboxylate compound.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode active material layer includes a positive electrode active material and a conductive agent.
  • the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (such as aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalene). Formed on substrates such as ethylene formate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the positive active material layer disposed on the surface of the positive current collector includes a positive active material.
  • the positive active material used in the present application may have any conventional positive active material used in secondary batteries.
  • the cathode active material may include one or more selected from the group consisting of lithium transition metal oxides, lithium-containing phosphates with an olivine structure, and their respective modified compounds.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide One or more of lithium nickel cobalt aluminum oxide and its modified compounds.
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate, composites of lithium iron phosphate and carbon, lithium manganese phosphate, composites of lithium manganese phosphate and carbon, lithium iron manganese phosphate, lithium iron manganese phosphate
  • the positive active material may be coated with carbon on its surface.
  • the positive active material layer optionally includes a conductive agent.
  • a conductive agent used for the cathode material may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive active material layer also includes a water-based binder.
  • Water-based adhesives are as described above.
  • the positive active material layer may additionally include other types of binders different from the water-based binder of the present invention, such as, but not limited to, styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF). ), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethylcellulose (CMC), polyvinyl alcohol (PVA) and polyvinyl butyral ( PVB) one or more.
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PAA polyacrylic acid
  • CMC carboxymethylcellulose
  • PVA polyviny
  • the positive electrode piece can be prepared according to methods known in the art.
  • the carbon-coated cathode active material, conductive agent and aqueous binder can be dispersed in a solvent (such as water) to form a uniform cathode composition; the cathode composition is coated on the cathode current collector and baked After drying, cold pressing and other processes, the positive electrode piece is obtained.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, where the negative electrode material layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite in its own thickness direction, and the negative electrode material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector can be a metal foil or a composite current collector.
  • the metal foil copper foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalene). Formed on substrates such as ethylene formate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode material layer usually contains a negative electrode active material and an optional binder, an optional conductive agent and other optional auxiliaries, and is usually formed by coating and drying the negative electrode composition.
  • the negative electrode composition coating is usually formed by dispersing the negative electrode active material and optional conductive agent and binder in a solvent and stirring evenly.
  • the solvent can be N-methylpyrrolidone (NMP) or deionized water.
  • the specific type of negative electrode active material is not limited. Active materials known in the art that can be used in the negative electrode of lithium ion secondary batteries can be used, and those skilled in the art can select according to actual needs.
  • the negative active material may be selected from one or more of graphite, soft carbon, hard carbon, mesocarbon microspheres, carbon fibers, carbon nanotubes, elemental silicon, silicon oxide compounds, silicon carbon composites, and lithium titanate. kind.
  • the conductive agent may be selected from one or more types of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the binder may be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), One or more of polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • auxiliaries are, for example, thickeners (such as sodium carboxymethyl cellulose (CMC-Na)).
  • Lithium-ion secondary batteries using an electrolyte also include a separator.
  • the isolation film is arranged between the positive electrode piece and the negative electrode piece to play the role of isolation.
  • the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one type selected from the group consisting of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic. Examples of plastics include polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • FIG. 1 shows a square-structured lithium ion secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the lithium ion secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • lithium-ion secondary batteries can be assembled into the battery module 4.
  • the number of lithium-ion secondary batteries contained in the battery module 4 can be one or more. Those skilled in the art can determine the specific number according to the application of the battery module 4. and capacity to choose.
  • a plurality of lithium ion secondary batteries 5 may be arranged in sequence along the length direction of the battery module. Of course, it can also be arranged in any other way. Furthermore, the plurality of lithium ion secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space in which a plurality of lithium ion secondary batteries 5 are accommodated.
  • the above-mentioned lithium ion secondary batteries 5 or battery modules 4 can be assembled into a battery pack 1 .
  • the number of lithium ion secondary batteries 5 or battery modules 4 contained in the battery pack 1 can be determined by those skilled in the art according to the battery pack 1 Choose your application and capacity.
  • the battery pack 1 may include a battery box and a plurality of battery cells arranged in the battery box.
  • the battery box includes an upper box 2 and a lower box 3.
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating battery cells.
  • this application also provides a device, which includes the battery pack provided by this application.
  • the battery pack can be used as a power source for the device or as an energy storage unit for the device.
  • the device may be, but is not limited to, a mobile device (such as a mobile phone, a laptop, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, or an electric golf ball). vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • a battery pack can be selected according to its usage requirements.
  • Figure 5 is an example device.
  • the device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • battery packs or battery modules can be used.
  • Adhesive used in the examples are Adhesive used in the examples:
  • Polyacrylic acid-acrylate-acrylamide binder 1 a terpolymer formed by free radical polymerization of acrylic acid, methyl acrylate and acrylamide.
  • the weight average molecular weight Mw is about 50,0000g/mol, and the T g is about 13°C. , in which the acrylic acid content is about 60wt%, the methyl acrylate content is about 20wt%, and the acrylamide content is about 20wt%.
  • Polyacrylic acid binder 2 acrylic acid homopolymer, weight average molecular weight Mw is about 20,0000g/mol, T g is about 106°C.
  • the purpose of dry powder mixing is to disperse and break large agglomerates in the powder under the action of high shear force dispersion, and at the same time achieve micro-uniform mixing of the powder, and deposit and disperse the particles on the surface of the large main material particles.
  • fine conductive carbon black SP
  • the deposited SP can form a good conductive network, making the resistance smaller and the consistency better.
  • the purpose of wetting and kneading the powder is to enable the solvent to disperse evenly and quickly infiltrate the powder, so as to prevent the powder from being kneaded directly without pre-wetting, resulting in excessive kneading in one part and insufficient kneading in another part, resulting in poor consistency of the slurry.
  • the stirring parameters for soaking the powder are set to: revolution 15-30rmp, rotation 600-1000rmp, time 1-5min; kneading is to separate the agglomerates and ensure good uniformity of the slurry. Parameter settings when kneading: revolution 15-30rmp, time 60-120min.
  • high-speed dispersion is to further disperse the small agglomerates in the slurry under high-speed shear conditions and evenly disperse them in the solvent.
  • Parameter settings revolution 15-30rmp, rotation 800-1500rmp, time 180-300min.
  • the positive electrode slurry is evenly coated on the positive electrode current collector, and then dried for 30 minutes under a nitrogen atmosphere, cold pressed, and cut to obtain a positive electrode sheet with a single-sided positive electrode sheet film weight of 350 mg/1540.25 mm 2 .
  • SBR binder styrene-butadiene rubber
  • CMC thickener sodium carboxymethylcellulose
  • An 8 ⁇ m polypropylene film is used as the base, and a 2 ⁇ m ceramic coating is coated on both sides as an isolation film.
  • Example 17 Based on the total weight of 100 parts by weight of dry matter, add 93.8 parts by weight of lithium iron phosphate and 4 parts by weight of conductive carbon black into a mixer for dry mixing and dispersion.
  • the dry mixing and dispersing conditions are: revolution 15-30rmp, rotation 600- 1000rmp, time 30-60min; 2) Add one-fifth to one-fourth of the formula amount of deionized water, an aqueous solution containing 2.2 parts by weight of binder 1, and 1.7 parts by weight of plasticizer EC to make powder Wet, and then knead; 3) Add the remaining formula amount of deionized water, and at the same time add an aqueous solution containing 0.5 parts by weight of LiOH, and perform high-speed dispersion to obtain a uniform solution with a solid content of approximately 60wt%; further, prepare the lithium iron phosphate
  • the equipment model used for the water-based cathode slurry is ROSS 100L double planetary dispersion mixing machine. Other steps of Example
  • Example 1 Stack the positive electrode piece, isolation film, and negative electrode piece in order in Example 1 so that the isolation film plays an isolation role between the positive and negative electrode pieces, then wind it to obtain a bare battery core, and weld the tabs to the bare battery core. , put the bare battery core into an aluminum case, bake it at 80°C to remove water, then inject electrolyte and seal it to obtain an uncharged battery. The uncharged battery then undergoes processes such as standing, hot and cold pressing, formation, shaping, and capacity testing to obtain the lithium-ion battery product of Example 1.
  • Adjust At the angle of the sample ensure that the upper and lower ends are in a vertical position, and then stretch the sample at a speed of 50mm/min until the sample is completely peeled off from the substrate. Record the displacement and force during the process. It is generally considered that the force when the force is balanced is the maximum. sheet adhesion.
  • Coat the positive electrode slurry on the surface of the current collector e.g.
  • a pole piece density 2.3g/cc
  • Bend the pole piece in half and fix it. Use a 2kg rolling roller to roll it once. Check whether there is light transmission and metal leakage in the folded part of the pole piece. If there is no light transmission and metal leakage, fold the pole piece in reverse and fix it. Use a 2kg rolling roller to roll it once and check whether the folded part of the pole piece is transparent and metal is leaking. Repeat the above steps until the folded part of the pole piece is transparent and metal is leaking.
  • Gram capacity test First, weigh the weight of 12mm light aluminum foil as m1, cut the positive electrode into 12mm small discs, weigh it as m2, press the negative electrode shell-shrapnel-gasket-lithium sheet-electrolyte-separator-electrolyte Assemble the 2032 button battery in the order of liquid - positive electrode - positive electrode shell, and use a pipette to remove 20ul of the electrolyte. And put the battery in the button battery sealing machine for hydraulic pressure. The test was conducted using a blue battery test system.
  • Example 1 the battery DC impedance test process is as follows: at 25°C, charge the battery corresponding to Example 1 with a constant current of 1/3C to 3.65V, and then charge with a constant voltage of 3.65V until the current is 0.05C. , after leaving it for 5 minutes, record the voltage V1. Then discharge at 1/3C for 30 seconds and record the voltage V2, then (V2-V1)/1/3C, we get the internal resistance DCR1 of the battery after the first cycle.
  • the internal resistance increase ratio of the battery in Example 1 in Table 1 is (DCRn-DCR1)/DCR1*100%.
  • the test process of Comparative Example 1 and other examples is the same as above.
  • the data in Table 1 are measured after 500 cycles under the above test conditions.
  • Example 5 of the present invention By comparing Example 5 of the present invention with Comparative Example 1, it can be seen that compared with the currently commonly used PAA adhesives, by including the terpolymer of the present invention in the water-based slurry, the deterioration of the water-based slurry can be significantly suppressed. It has a tendency to gel, giving it satisfactory fluidity after standing for 24 hours. At the same time, it can be seen from the results of Examples 1-7 that by adjusting the proportion of the terpolymer in the main components of the slurry (i.e., cathode active material, conductive agent and binder), cyclic DCR can be achieved Optimization to minimize the increase in DC impedance (Embodiment 5).
  • the proportion of the terpolymer in the main components of the slurry i.e., cathode active material, conductive agent and binder
  • Example 8-16 different proportions of the small molecule plasticizer ethylene carbonate (EC) are added on the basis of Example 5, which significantly improves the brittleness of the positive electrode sheet prepared therefrom and eliminates the brittleness on the surface of the electrode sheet. slight cracks, giving the pole piece a satisfactory appearance.
  • EC small molecule plasticizer ethylene carbonate
  • Examples 17-25 are based on Example 12 and additionally add alkaline additive LiOH in different proportions, which significantly increases the gram capacity of the secondary battery prepared thereby. By adjusting the amount of LiOH added, the increase in capacity can be maximized.
  • Example 22 by adding 2.0 parts by weight of LiOH, the gram capacity was increased to 155.8 mAh/g, which was significantly improved compared to the capacity of 151.3 mAh/g in Example 12.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

本申请涉及一种用于正极极片水系浆料的水性粘接剂，其含有至少一种三元共聚物，所述三元共聚物衍生自(甲基)丙烯酸、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺，或者衍生自(甲基)丙烯腈、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺。本申请还涉及包含所述水性粘接剂的用于制备正极极片的水系浆料、由所述水系浆料所制备的正极极片、包含所述正极极片的二次电池以及包含该二次电池的电池包以及用电装置。

Description

用于正极极片的水性粘接剂以及由其制备的正极极片 技术领域
本申请涉及一种用于正极极片的水性粘接剂，还涉及包含所述水性粘接剂的用于制备正极极片的水系浆料、由所述水系浆料所制备的正极极片、包含所述正极极片的二次电池以及包含该二次电池的电池包以及用电装置。
背景技术
二次电池因其成本低、寿命长、安全性好等特点成为最受欢迎的能量存储系统，现已被广泛应用于纯电动汽车、混合电动汽车以及智能电网等领域。二次电池主要由正极极片、负极极片、隔离膜及电解质组成，其中电池极片(例如正极极片)的制备需要使用粘接剂材料将极片活性物质与导电剂以及其他添加剂牢固地粘合在一起。由于传统使用的油系粘接剂基于环保以及安全性等因素越来越不受青睐，本领域正在不断开发水性粘接剂用于电极极片的制备。目前较常规使用的水性粘接剂为聚丙烯酸(PAA)系粘接剂。但是，此类粘接剂在使用时比较容易凝胶，使得正极组合物涂布之后容易开裂甚至脱模，脆性较差。
因此，目前仍然需要提供一种制备二次电池正极极片所用的水性粘接剂以及包含其的水系浆料，其可制备具有改善特性的正极极片，使得由所述正极极片构建的二次电池具有改善的力学性能和电学性能。
发明内容
本申请是鉴于上述课题而进行的，其目的在于提供一种制备二次电池 正极极片所用的水性粘接剂以及包含其的水系浆料，以解决由其制备二次电池过程中容易凝胶、极片容易开裂以及脆性较差的技术问题。
为了达到上述目的，本申请第一方面提供一种水性粘接剂，其中包含至少一种三元共聚物，所述三元共聚物衍生自(甲基)丙烯酸、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺，或者衍生自(甲基)丙烯腈、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺，其中所述三元共聚物的玻璃化转变温度Tg为-20℃至40℃，可选地为0℃至20℃。
本申请的水性粘接剂通过包含如上所定义的三元共聚物，可解决由其制备的正极水系浆料容易发生凝胶现象的问题，使得水系浆料在长时间静置后仍可具备良好的流动性，由此显著延长了水系浆料的加工时间以及降低了使用难度。不囿于任何理论，本发明人认为本申请的水性粘接剂所包含的三元共聚物在主链中共聚了部分的酯基，使其具有较低的玻璃化转变温度，因此不容易脆化，同时还能够保持丙烯酸类粘接剂的较强的粘接性能。腈基/羧基在共聚物中具有丰富的极性基团，如-CN位于分子链的主链段，由于-CN基团和基质电负性之间的偶极相互作用，具有很强的粘附性。-COOH基团能够与Al箔表面氧化层中-OH基团形成较强的氢键，以确保活性材料牢固附着在集流体上，从而提搞了极片的粘结力，避免了极片在涂布或冷压过程中出现脱膜、掉粉等加工异常。酰胺基团可以增加粘结力。
在任意实施方式中，所述三元共聚物的重均分子量Mw为40,0000-110,0000g/mol，可选地为40,0000-80,0000g/mol，进一步可选地为45,0000-60,0000g/mol。在任意实施方式中，在所述三元共聚物中，各单体单元的重量比例为：(甲基)丙烯酸或(甲基)丙烯腈为50-70％，(甲基)丙烯酸C 1-C 20烷基酯为15-35％，以及(甲基)丙烯酰胺为15-35％；可选地，各单体单元的重量比例为：(甲基)丙烯酸或(甲基)丙烯腈为50- 60％，(甲基)丙烯酸C 1-C 20烷基酯为20-30％，以及(甲基)丙烯酰胺为20-30％。
在任意实施方式中，所述三元共聚物可具有以下通式(I)或(II)的结构：
Figure PCTCN2022115119-appb-000001
其中，R 1彼此相同或不同地独立地为H或者甲基，
R 2为C 1-C 20烷基，可选地为C 1-C 8烷基，进一步可选地为甲基、乙基、正丙基、异丙基、正丁基、仲丁基、叔丁基、正戊基、正辛基、异辛基，
x、y和z独立地为选自100-10000，可选地为选自500-5000的整数。
在一些实施方式中，所述(甲基)丙烯酸C 1-C 20烷基酯选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸丁酯、甲基丙烯酸异辛酯或其组合。
本申请的第二方面提供一种用于制备正极极片的水系浆料水系浆料，其包含正极活性材料、导电剂和上文所述的水性粘接剂，以及任选地水和分散剂，其中所述水性粘接剂的比例为0.4-3重量％，可选地为1.5-2.5重量％，进一步可选地为2-2.3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。
本申请的用于制备正极极片的水系浆料通过包含如上所限定的水性粘接剂，可以有效抑制凝胶倾向，提高粘接力，改善由其制备的正极极片的 脆性，以及电学性能，例如循环直流阻抗(DCR)。已发现，通过包含特定比例范围内的水性粘接剂，所述水系浆料的流动性(即，抗凝胶能力)可实现最优效果。
在任意实施方式中，所述正极活性材料、导电剂和水性粘接剂的重量比为92-96：1-5：0.5-3，可选地为93-95：3-5：1.5-2.5，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。
在任意实施方式中，所述正极活性材料选自磷酸铁锂、磷酸锰锂、磷酸钴锂、磷酸铁锰锂、锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物中的一种或多种，可选地为磷酸铁锂。所述导电剂选自导电炭黑、超导炭黑、导电石墨、乙炔黑、科琴黑、石墨烯、碳纳米管中的一种或多种。
在任意实施方式中，所述水系浆料还包含0.4-3重量％的增塑剂，可选地为0.8-2重量％，进一步可选地为1.5-1.8重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。所述增塑剂选自聚乙二醇(PEG)、碳酸亚乙酯(EC)、丙三醇等的一种或多种，可选地为碳酸亚乙酯。已发现，通过添加特定含量的小分子增塑剂，可显著降低由其制备的正极极片的脆性，改善极片外观。
在任意实施方式中，所述水系浆料还包含0.5-3重量％的碱性添加剂，可选地为1.2-2.5重量％，进一步可选地为1.8-2.3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。所述碱性添加剂选自碱金属氢氧化物、碱金属碳酸盐、碱金属磷酸盐以及碱金属羧酸盐，可选地为锂的氢氧化物、碳酸盐、磷酸盐以及羧酸盐，进一步可选地为LiOH和Li 2CO 3。已发现，通过添加特定含量的碱性添加剂，特别是LiOH和Li 2CO 3，可显著增加所制备的二次电池的克容量。
在任意实施方式中，所述水系浆料的固含量为30-75重量％，可选地 为45-65重量％。在任意实施方式中，所述分散剂选自聚酰胺类分散剂、聚(甲基)丙烯酸酯类分散剂、聚羧酸盐类分散剂、磺酸盐类分散剂、硅酸盐类分散剂、磷酸盐类分散剂、聚乙烯亚胺分散剂、含氨基聚合物及其胺盐类分散剂。
在任意实施方式中，所述水系浆料以水性分散体的形式存在，或者以所述水性分散体经过干燥而得到的产物形式而存在。
本申请的第三方面提供一种正极极片，其通过使用选自本申请的第二方面的水系浆料而制备。
本申请的第四方面提供一种二次电池，其包括选自本申请的第三方面的正极极片。
本申请的第五方面提供一种电池包，其包括选自本申请的第四方面的二次电池。
本申请的第六方面提供一种用电装置，其包括选自本申请的第四方面的二次电池或者本申请的第五方面的电池包。
附图说明
为了更清楚地说明本申请的技术方案，下面将对本申请实施例中所需要使用的附图作简单的介绍。显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请一个实施方式中的锂离子二次电池的示意图。
图2是图1所示的本申请一个实施方式中的锂离子二次电池的分解图。
图3是本申请一个实施方式中的电池包的示意图。
图4是图3所示的本申请一个实施方式中的电池包的分解图。
图5是本申请一个实施方式中的电池包用作电源的装置的示意图。
附图标记说明
1电池包
2上箱体
3下箱体
4电池模块
5锂离子二次电池
51壳体
52电极组件
53盖板
具体实施方式
为了简明，本申请具体地公开了一些数值范围。然而，任意下限可以与任意上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
目前的二次电池中，由于具有成本低廉且环境友好的特点，采用水作为溶剂的水系正极极片组合物来制备正极极片越来越受到关注。然而，目前常规使用的水性粘接剂，如PAA体系的粘接剂，存在诸多问题。例如，在水系磷酸铁锂(LFP)正极浆料中，LFP里含有亚铁离子，极不稳定，具有很强的还原性，容易失去电子。并且，亚铁离子在LFP中含量较高，PAA中具有较多的羧酸根离子，酸与二价铁离子会互相结合(亚铁离子实际没有游离出来，晶格表面会有一定的亚铁离子)。一个二价亚铁离子与 两个羧酸根形成一个离子键，形成交联。高密度的离子键导致导致水性浆料没有流动性，形成凝胶，进而导致极片在加工中出现凝胶、涂布开裂、极片硬脆等一系列问题。并且在水性浆料中，这种结合会影响二价铁离子和锂离子的浓度，导致克容量低于油性体系。
因此，本领域需要提供一种水性粘接剂，其可以特定含量加入水系浆料中，用于制备具有改善的性能的正极极片以及二次电池。
具体的，本申请第一方面提供一种水性粘接剂，其包含至少一种三元共聚物，所述三元共聚物衍生自(甲基)丙烯酸、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺，或者衍生自(甲基)丙烯腈、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺，其中所述三元共聚物的玻璃化转变温度Tg为-20℃至40℃，可选地为0℃至20℃。
本发明人发现，本申请的水性粘接剂所包含的三元共聚物在主链中共聚了部分的酯基，使其具有较低的玻璃化转变温度，因此不容易脆化，同时还能够保持丙烯酸类粘接剂的较强的粘接性能。所述三元共聚物可通过三种单体的自由基聚合得到，例如，通过首先将一部分引发剂加入有机溶剂中；然后依次加入相应的三种单体，以及可能的链转移剂；随后在升高的温度下(如60-100℃)聚合2-24小时，期间可将剩余的引发剂加入溶液中；聚合完成后，通过沉淀、离心和真空干燥，即可得到所述三元共聚物。还可通过特定的基团对所述三元共聚物进行封端，最终得到的三元共聚物可以另外包含少量的封端基团，以及少量的链转移剂残留基团；但是由于其含量非常低，对于所述三元共聚物没有实质影响，因此在本文中不作特别限定。
在一些实施方式中，所述三元共聚物可具有以下通式(I)或(II)的结构：
Figure PCTCN2022115119-appb-000002
其中，R 1彼此相同或不同地独立地为H或者甲基，
R 2为C 1-C 20烷基，可选地为C 1-C 8烷基，进一步可选地为甲基、乙基、正丙基、异丙基、正丁基、仲丁基、叔丁基、正戊基、正辛基、异辛基，
x、y和z独立地为选自100-10000，可选地为选自500-5000的整数。在一些实施方式中，x为选自3000-5000的整数，y为选自800-1500的整数，z为选自800-1500的整数。
在本申请中，上述通式(I)或(II)的结构并不旨在将本申请的三元共聚物限定为(甲基)丙烯酸、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺，或者(甲基)丙烯腈、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺的交替的嵌段共聚物形式，而是表明其中各单体单元的类型及数量。可以理解的是，以上结构还包括上述单体单元的其他可能的嵌段共聚物以及无规共聚物。本申请的水性粘接剂也可包含具有上述通式(I)或(II)的结构的三元共聚物的混合物。x、y和z的选择应使得最终得到的共聚物的分子量满足上文所述的限定范围。另外， *号对应的是所述三元共聚物的端基。如上文所述，其含量非常低，对于所述三元共聚物没有实质影响。
在一些实施方式中，在所述三元共聚物中，各单体单元的重量比例为：(甲基)丙烯酸或(甲基)丙烯腈为50-70％，(甲基)丙烯酸C 1-C 20烷基酯为15-35％，以及(甲基)丙烯酰胺为15-35％；可选地，各单体单 元的重量比例为：(甲基)丙烯酸或(甲基)丙烯腈为50-60％，(甲基)丙烯酸C 1-C 20烷基酯为20-30％，以及(甲基)丙烯酰胺为20-30％。通过进一步选择三种单体单元的重量比例，可进一步优化所得三元共聚物的粘接力以及脆性。可通过调节三种单体的加入量来调节其在三元共聚物中的相应比例。在一些实施方式中，所述(甲基)丙烯酸C 1-C 20烷基酯选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸丁酯、甲基丙烯酸异辛酯或其组合。所述三元共聚物可为嵌段共聚物或者无规共聚物，其重均分子量Mw可为40,0000-110,0000g/mol，可选地为40,0000-80,0000g/mol，进一步可选地为45,0000-60,0000g/mol。通过特定的分子量选择，可进一步调节所述三元共聚物的粘度以及因此调节其流动性。所述三元共聚物的玻璃化转变温度Tg为-20℃至40℃，可选地为0℃至20℃。较低的Tg使得该三元共聚物具有较低的粘度，有助于使其在静置一定时间后仍可具有较高的流动性。所述Tg可通过以下测试方法得到：1.制样：将薄膜状样品冲成直径6mm的小圆片，称取1～3mg，放入Al坩埚压平，坩埚盖子倒扣，固体状样品，称取1～3mg，盖上坩埚盖；2.参数设置：氮气气氛，吹扫气50mL/min，保护气100mL/min；3.温升程序：10℃/min，35℃～300℃，300℃保温3min；10℃/min，300℃～35℃，35℃保温3min；10℃/min，35℃～300℃，结束。所用仪器为型号为Discovery 250的差示扫描量热仪。
本申请的水性粘接剂除了所述三元共聚物以外，还可任选地包含其他添加剂，如溶剂、分散剂、成膜助剂等。在一些实施方式中，所述水性粘接剂仅为上文所述的三元共聚物。
本申请的第二方面提供一种用于制备正极极片的水系浆料，其包含正极活性材料、导电剂和上文所述的水性粘接剂，以及任选地水和分散剂，其中所述水性粘接剂的比例为0.4-3重量％，可选地为1.5-2.5重量％，进 一步可选地为2-2.3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。
本申请的用于制备正极极片的水系浆料通过包含特定含量的如上所限定的水性粘接剂，可以有效抑制凝胶倾向，提高粘接力，改善由其制备的正极极片的脆性，以及电学性能，例如循环直流阻抗(DCR)。已发现，通过进一步选择特定比例范围内的水性粘接剂，所述水系浆料的流动性(即，抗凝胶能力)可实现最优效果。当所述水性粘结剂在极片中含量过低时，达不到足够粘结效果，无法将足量的导电剂和正极活性材料粘结到一起，极片的粘结力小，导致极片在加工过程中出现脱模现象或者电池在长循环过程中活性材料粒子跑到负极，造成极大的安全隐患。相反，当极片中所述水性粘结剂含量过高时，会导致活性材料包覆太厚，阻碍锂离子在活性材料中的传输，使得锂离子不易放出或嵌入，造成极片膜片电阻大，从而造成电池阻抗增大。同时，过多的粘结剂不仅会占据主材的载量，导致电池的能量密度降低，还会使极片吸液膨胀，导致电池的直流阻抗增大。通过加入合适量的粘结剂能够有效维持极片在循环过程中的反弹，保持合适的吸液能力，抑制长期循环过程中直流阻抗的增长。
在一些实施方式中，在所述水系浆料中，正极活性材料、导电剂和水性粘接剂的重量比为92-96：1-5：0.5-3，可选地为93-95：3-5：1.5-2.5。在所述水系浆料中，正极活性材料、导电剂和水性粘接剂的重量比可通过改变起始材料的加入量来进行调节。
在一些实施方式中，所述正极活性材料选自磷酸铁锂、磷酸锰锂、磷酸钴锂、磷酸铁锰锂、锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物中的一种或多种，可选地为磷酸铁锂。所述导电剂选自导电炭黑、超导炭黑、导电石墨、乙炔黑、科琴黑、石墨烯、碳纳米管中的一种或多种。
在一些实施方式中，所述水系浆料还包含0.4-3重量％的增塑剂，可选地为0.8-2重量％，进一步可选地为1.5-1.8重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。所述增塑剂可选自聚乙二醇(PEG)、碳酸亚乙酯(EC)、丙三醇等的一种或多种，可选地为碳酸亚乙酯。已发现，通过添加特定含量的小分子增塑剂，可显著降低由其制备的正极极片的脆性，改善极片外观。对于丙烯腈或丙烯酸类共聚物，其天然具有硬脆的弱点，导致裸电芯在热压时，出现内圈断裂，漏金属等，并导致电解液不断的腐蚀铝箔，进而影响电性能。常见的方法时在共聚物中共聚部分酯类或者醚类，但是这种方法对于解决共聚物的柔性的效果并不显著。酯类的接枝，还会造成共聚物的溶胀过大，导致电芯吸液膨胀，恶化电芯的DCR，进而影响电性能。在本申请中，发明人发现，通过加入小分子增塑剂如聚乙二醇(PEG)、碳酸乙烯酯(EC)、丙三醇等来破坏丙烯酸-丙烯酸酯的强分子间作用力(氢键)，可有效改善由其所得极片的脆性。然而，如果所述小分子增塑剂的加入量过多，未参加反应的分子(如EC)在极片制造过程容易结晶，进而影响电芯性能。因此，所述小分子增塑剂在水系浆料中的含量应控制在如上所述的适宜的范围内。
在一些实施方式中，所述水系浆料还包含0.5-3重量％的碱性添加剂，可选地为1.2-2.5重量％，进一步可选地为1.8-2.3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。所述碱性添加剂选自碱金属氢氧化物、碱金属碳酸盐、碱金属磷酸盐以及碱金属羧酸盐，可选地为锂的氢氧化物、碳酸盐、磷酸盐以及羧酸盐，进一步可选地为LiOH和Li 2CO 3。已发现，通过添加特定含量的碱性添加剂，特别是LiOH和Li 2CO 3，可显著增加所制备的二次电池的克容量。本发明人发现，水性体系的极片组合物会影响正极活性材料例如磷酸铁锂的克容量发挥，其原因主要是磷酸铁锂类物质在水中会解离出二价的亚铁离子以及锂离子，导致 部分克容量由于锂离子的失活无法发挥。通过在水性浆料的制备过程加入一定量的碱性添加剂，如LiOH和Li 2CO 3，调节水性浆料的pH，抑制铁离子的水解和溶出，可有效减少锂离子的失活。
在一些实施方式中，所述水系浆料的固含量为30-75重量％，可选地为45-65重量％。当然，所述组合物也可以包含少量的有机溶剂，例如乙醇、丙酮、N,N-二甲基吡咯烷酮等，但是其含量应不多于5％，可选地低于1％。在一些实施方式中，所述水系浆料还可包含一定量的分散剂，例如0.5-5重量％，可选地1-3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。所述分散剂选自聚酰胺类分散剂、聚(甲基)丙烯酸酯类分散剂、聚羧酸盐类分散剂、磺酸盐类分散剂、硅酸盐类分散剂、磷酸盐类分散剂、聚乙烯亚胺分散剂、含氨基聚合物及其胺盐类分散剂。
在一些实施方式中，所述水性浆料可以以水性分散体的形式存在，或者以所述水性分散体经过干燥而得到的产物形式而存在。所述水性浆料可通过将正极活性材料、导电剂和水性粘接剂以特定的重量比例加入到去离子水中形成浆料，任选地加入一定量的分散剂并搅拌均匀，然后再通过去离子水将其固含量调节到预定范围。所得水性浆料可通过刮涂、辊涂或喷涂的方式涂覆在正极集流体上，然后在烘箱中在升高的温度下进行干燥，去除水和任选地有机溶剂，从而得到干形式的正极活性物质层。本发明的水性浆料也包含这种干形式的层状组合物，其中可含有一定量的残留水。
本申请的第三方面提供一种正极极片，其通过使用选自本申请的第二方面的水系浆料而制备。
本申请的第四方面提供一种二次电池，其包括选自本申请的第三方面的正极极片。
本申请的第五方面提供一种电池包，其包括选自本申请的第四方面的二次电池。
本申请的第六方面提供一种用电装置，其包括选自本申请的第四方面的二次电池或者本申请的第五方面的电池包。
本申请的二次电池的各组件的材料可在宽范围内进行选择。在一些实施方案中，所述二次电池特别地为锂离子二次电池。下文对所述锂离子二次电池的电池单体进行详细阐述。
通常情况下，锂离子二次电池包括正极极片、负极极片、隔离膜及电解质。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。隔离膜设置在正极极片和负极极片之间，起到隔离的作用。电解质在正极极片和负极极片之间起到传导离子的作用。
[电解液]
电解液在正极极片和负极极片之间起到传导离子的作用。电解液包括电解质盐和溶剂。
在本申请中，电解质盐可为锂离子二次电池中的常用电解质盐，例如锂盐，包括可为上述作为高热稳定性盐的锂盐、作为低阻抗添加剂的锂盐或抑制铝箔腐蚀的锂盐。作为实例，电解质盐可选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)、氟磺酸锂(LiSO 3F)、二氟二草酸盐(NDFOP)、Li 2F(SO 2N) 2SO 2F、KFSI、CsFSI、Ba(FSI) 2及LiFSO 2NSO 2CH 2CH 2CF 3中的一种以上。
溶剂的种类没有特别的限制，可根据实际需求进行选择。在一些实施方式中，溶剂为非水性溶剂。可选地，溶剂可包括链状碳酸酯、环状碳酸酯、羧酸酯中的一种或几种。在一些实施方式中，溶剂可选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯 (DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、四氢呋喃、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种以上。
在一些实施方式中，电解液中还可选地包括其他添加剂。例如添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、以及改善电池低温性能的添加剂等。作为示例，添加剂选自含有不饱和键的环状碳酸酯化合物、卤素取代的环状碳酸酯化合物、硫酸酯化合物、亚硫酸酯化合物、磺酸内酯化合物、二磺酸化合物、腈化合物、芳香化合物、异氰酸酯化合物、磷腈化合物、环状酸酐化合物、亚磷酸酯化合物、磷酸酯化合物、硼酸酯化合物、羧酸酯化合物中的至少一种。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极活性物质层，正极活性物质层包括正极活性材料和导电剂。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极活性物质层设置在正极集流体相对的两个表面的其中任意一者或两者上。
本申请的锂离子二次电池中，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(例如铝、铝合金、镍、镍合金、钛、钛合金、银及银合金 等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
设置于正极集流体的表面上的正极活性物质层包括正极活性材料。本申请中所用的正极活性材料可具有二次电池中使用的任意常规正极活性材料。在一些实施方式中，正极活性材料可包含选自锂过渡金属氧化物、橄榄石结构的含锂磷酸盐及其各自的改性化合物中的一种或几种。锂过渡金属氧化物的示例可包括但不限于锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其改性化合物中的一种或几种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料及其改性化合物中的一种或几种。这些材料均可以通过商业途径获得。正极活性材料表面上可包覆有碳。
正极活性物质层可选地包括导电剂。但对导电剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。作为示例，用于正极材料的导电剂可以选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种以上。
正极活性物质层还包括水性粘结剂。水性粘接剂如上文所述。然而，正极活性物质层还可另外包括不同于本发明的水性粘接剂的其他类型的粘接剂，例如，但不限于丁苯橡胶(SBR)、水性丙烯酸树脂、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚丙烯酸(PAA)、羧甲基纤维素(CMC)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或几种。
本申请中可按照本领域已知的方法制备正极极片。作为示例，可以将包覆碳的正极活性材料、导电剂和水性粘结剂分散于溶剂(例如水)中，形成均匀的正极组合物；将正极组合物涂覆在正极集流体上，经烘干、冷压等工序后，得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极材料层，所述负极材料层包括负极活性物质。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极材料层设置在负极集流体相对的两个表面中的任意一者或两者上。
本申请的锂离子二次电池中，负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(例如铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
本申请的锂离子二次电池中，负极材料层通常包含负极活性物质以及可选的粘结剂、可选的导电剂和其他可选助剂，通常是由负极组合物涂布干燥而成的。负极组合物涂通常是将负极活性物质以及可选的导电剂和粘结剂等分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水。
负极活性物质的具体种类不做限制，可以采用本领域已知的能够用于锂离子二次电池负极的活性物质，本领域技术人员可以根据实际需求进行选择。作为示例，负极活性物质可选自石墨、软碳、硬碳、中间相碳微 球、碳纤维、碳纳米管、单质硅、硅氧化合物、硅碳复合物、钛酸锂中的一种或几种。
作为示例，导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种以上。
作为示例，粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种以上。
其他可选助剂例如是增稠剂(如羧甲基纤维素钠(CMC-Na))等。
[隔离膜]
采用电解液的锂离子二次电池中还包括隔离膜。隔离膜设置在正极极片和负极极片之间，起到隔离的作用。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种以上。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，所述二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，所述二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。所述二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)以及聚丁二酸丁二醇酯(PBS)等。
本申请对所述二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的锂离子二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。锂离子二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，锂离子二次电池可以组装成电池模块4，电池模块4所含锂离子二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块4的应用和容量进行选择。在电池模块4中，多个锂离子二次电池5可以是沿电池模块的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个锂离子二次电池5进行固定。可选地，电池模块4还可以包括具有容纳空间的外壳，多个锂离子二次电池5容纳于该容纳空间。
在一些实施方式中，上述锂离子二次电池5或者电池模块4可以组装成电池包1，电池包1所含锂离子二次电池5或者电池模块4的数量可由本领域技术人员根据电池包1的应用和容量进行选择。
图3和图4是作为一个示例的电池包1。参照图3和图4，在电池包1中可以包括电池箱和设置于电池箱中的多个电池单体。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池单体的封闭空间。
另外，本申请还提供一种装置，所述装置包括本申请提供的电池包。所述电池包可以用作所述装置的电源，也可以用作所述装置的能量存储单元。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。作为所述装置，可以根据其使用需求来选择电池包。
图5是作为一个示例的装置。该装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对锂离子二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。如果无特殊标明，所有含量比例均为重量比，并且所有实验均在常温(25℃)和常压下进行。
实施例中所用的粘接剂：
聚丙烯酸-丙烯酸酯-丙烯酰胺粘结剂1：丙烯酸、丙烯酸甲酯和丙烯酰胺通过自由基聚合形成的三元共聚物，重均分子量Mw约为50,0000g/mol，T g约为13℃，其中丙烯酸含量约为60wt％，丙烯酸甲酯含量约为20wt％，并且丙烯酰胺含量约为20wt％。
聚丙烯酸类粘结剂2：丙烯酸均聚物，重均分子量Mw约为 20,0000g/mol，T g约为106℃。
实施例1
【正极极片的制备】
实施例1：
1)基于100重量份干物质的总重量计，将94.6重量份的磷酸铁锂和4重量份的导电炭黑加入搅拌器中进行干混分散，干混分散条件为：公转15-30rmp，自转600-1000rmp，时间30-60min；2)再加入配方量五分之一到四分之一的去离子水、包含0.6重量份的聚丙烯酸-丙烯酸酯-丙烯酰胺粘结剂1的水溶液进行粉料浸湿，再捏合；3)再加入剩余配方量的去离子水，进行高速分散，获得固含量约为60wt％的均一溶液；进一步的，制备该磷酸铁锂水性正极浆料所采用的设备型号为ROSS 100L双行星分散式搅拌机器。
干粉混合的目的是，在高剪切力分散的作用下，能够使得粉料中大的团聚体得到分散破裂并同时实现了粉料的微观均匀混合，在大的主材颗粒表面沉积了分散开的细小的导电炭黑(SP)。沉积的SP能够形成良好的导电网络，使得电阻变小、一致性变好。
粉料浸湿、捏合的目的是，使得溶剂能够均匀分散并快速浸润粉料，避免粉料由于没有进行预浸润而直接进行捏合，使得局部捏合过度而另一部分捏合不足，导致浆料一致性差、沉降等异常情况的出现。粉料浸湿的搅拌参数设置为：公转15-30rmp，自转600-1000rmp，时间1-5min；捏合，是为了将团聚体分开，保证浆料的良好均一性状态。捏合时参数设置：公转15-30rmp，时间60-120min。
高速分散的目的，使得浆料中的小团聚体在高速剪切的条件下进一步分散，并均匀的分散在溶剂中，参数设置：公转15-30rmp，自转800- 1500rmp，时间180-300min。
之后将正极浆料均匀涂覆于正极集流体上，之后经过在氮气气氛条件下烘干30min、冷压、分切，得到单侧正极极片膜层重量为350mg/1540.25mm 2的正极极片。
【负极极片的制备】
将活性物质人造石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)按照重量比为96.2：0.8：0.8：1.2溶于溶剂去离子水中，混合均匀后制备成负极浆料；将负极浆料一次或多次均匀涂覆在负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。
【电解液的制备】
在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将有机溶剂碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)按照体积比3/7混合均匀，加入12.5％LiPF6锂盐溶解于有机溶剂中，搅拌均匀，得到实施例1的电解液。
【隔离膜】
以8μm聚丙烯膜为基底，双面涂布2μm后的陶瓷涂层后作为隔离膜。
实施例2-7
除将粘结剂的重量份改为1.0、1.4、1.8、2.2、2.6、3.0外，实施例2-7的其他步骤与实施例1相同。
实施例8
基于100重量份干物质的总重量计，将93.8重量份的磷酸铁锂和4重 量份的导电炭黑加入搅拌器中进行干混分散，干混分散条件为：公转15-30rmp，自转600-1000rmp，时间30-60min；2)再加入配方量五分之一到四分之一的去离子水、包含2.2重量份的粘结剂1的水溶液、0.5重量份的增塑剂EC进行粉料浸湿，再捏合；3)再加入剩余配方量去离子水，进行高速分散，获得固含量约为60wt％的均一溶液；进一步的，制备该磷酸铁锂水性正极浆料所采用的设备型号为ROSS 100L双行星分散式搅拌机器。实施例8的其他步骤与实施例1相同
实施例9-16
除将增塑剂EC的重量份改为0.8、1.1、1.4、1.7、2.0、2.3、2.6、2.9外，实施例9-16的其他步骤与实施例8相同。
实施例17
基于100重量份干物质的总重量计，将93.8重量份的磷酸铁锂和4重量份的导电炭黑加入搅拌器中进行干混分散，干混分散条件为：公转15-30rmp，自转600-1000rmp，时间30-60min；2)再加入配方量五分之一到四分之一的去离子水、包含2.2重量份的粘结剂1的水溶液、1.7重量份的增塑剂EC进行粉料浸湿，再捏合；3)再加入剩余配方量去离子水，同时加入包含0.5重量份LiOH的水溶液，进行高速分散，获得固含量约为60wt％的均一溶液；进一步的，制备该磷酸铁锂水性正极浆料所采用的设备型号为ROSS 100L双行星分散式搅拌机器。实施例17的其他步骤与实施例1相同。
实施例18-25
除将LiOH的重量份改为0.8、1.1、1.4、1.7、2.0、2.3、2.6、2.9外，
实施例18-25的其他步骤与实施例17相同。
对比例1
1)基于100重量份干物质的总重量计，将93.8重量份的磷酸铁锂和4重量份的导电炭黑加入搅拌器中进行干混分散，干混分散条件为：公转15-30rmp，自转600-1000rmp，时间30-60min；2)再加入配方量五分之一到四分之一的去离子水、包含2.2重量份的聚丙烯酸类粘结剂2的水溶液进行粉料浸湿，再捏合；3)再加入剩余配方量去离子水，进行高速分散，获得固含量约为60wt％的均一溶液；进一步的，制备该磷酸铁锂水性正极浆料所采用的设备型号为ROSS 100L双行星分散式搅拌机器。对比例1的其他步骤与实施例1相同。
【锂离子电池的制备】
将实施例1正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到裸电芯，给裸电芯焊接极耳，并将裸电芯装入铝壳中，并在80℃下烘烤除水，随即注入电解液并封口，得到不带电的电池。不带电的电池再依次经过静置、热冷压、化成、整形、容量测试等工序，获得实施例1的锂离子电池产品。
对比例1和实施例2-25的锂离子电池产品同样按照上述步骤制备。
【极片性能测试】
1、正极极片的粘结力测试
将正极极片裁剪为20*100mm尺寸的测试试样，备用；极片用双面胶粘接需要测试的那一面，并用压辊压实，使之与极片完全贴合；试样的双面胶的另外一面粘贴于不锈钢表面，将试样一端反向弯曲，弯曲角度为 180°；采用高铁拉力机测试，将不锈钢一端固定于拉力机下方夹具，试样弯曲末端固定于上方夹具，调整试样角度，保证上下端位于垂直位置，然后以50mm/min的速度拉伸试样，直到试样全部从基板剥离，记录过程中的位移和作用力，一般认为受力平衡时的力为极片的粘结力。
2、极片脆性测试
将正极浆料涂覆于集流体(如)表面，经过干燥、冷压制成极片(压密2.3g/cc)，将制备完成的极片裁剪为20*100mm尺寸的测试试样，备用；1.将极片弯曲对折固定好，使用2kg重的碾压辊碾压一次，查看极片对折处是否透光漏金属；若无透光漏金属，.再将极片反过来对折固定住，使用2kg的碾压辊碾压一次，查看极片对折处是否透光漏金属，重复以上步骤，直至极片对折处透光漏金属为止。
3、浆料粘度测试
选取合适的转子，固定好粘度计，将正极浆料置于粘度计下方，浆料恰好淹没转子的刻度线，仪器型号：上海方瑞NDJ-5S，转子：63#(2000-10000mPa.s)、64#(10000-50000mPa.s)，转速：12r/min，测试温度：25℃，测试时间为5min，待示数稳定读取数据。
4、极片外观测试:
正极极片制备完成后观察正极极片的表面状态，包括是否平整、是否有裂痕以及是否有颗粒团聚等，若均无上述现象，记录为OK，若存在其中一种现象，予以记录。
5、浆料流动性测试：
用药匙取适量正极浆料，观察正极浆料的自然下流是否流畅。若自然下流顺畅判定为OK；若流动性不好，浆料出现果冻状，成块，表明出现凝胶，判定为NG。
【电池性能测试】
1、克容量发挥测试
克容量发挥测试：首先称取12mm光铝箔重量为m1,将极片正极切成12mm的小圆片，称重为m2,按负极壳-弹片-垫片-锂片-电解液-隔膜-电解液-正极-正极壳的顺序，组装2032型扣式电池，电解液使用移液枪移取20ul。并将电池在纽扣电池封装机进行液压。测试采用蓝电电池测试系统进行测试。
2、电池直流阻抗测试
以实施例1为例，电池直流阻抗测试过程如下：在25℃下，将实施例1对应的电池，以1/3C恒流充电至3.65V，再以3.65V恒定电压充电至电流为0.05C，搁置5min后，记录电压V1。然后再以1/3C放电30s，记录电压V2，则(V2-V1)/1/3C，得到第一次循环后电池的内阻DCR1。对上述同一个电池重复以上步骤，并同时记录循环第n次后电池的内阻DCRn(n＝1、2、3……100)，将上述DCR1、DCR2、DCR3……DCR100这100个点值为纵坐标，以对应的循环次数为横坐标，得到如附图5所示的实施例1的磷酸铁锂正极活性材料对应的电池放电DCR与循环次数的曲线图。
该测试过程中，第一次循环对应n＝1、第二次循环对应n＝2、……第100次循环对应n＝100。表1中实施例1的电池内阻增大比率＝(DCRn-DCR1)/DCR1*100％，对比例1以及其他实施例的测试过程同上。表1中的数据是在上述测试条件下循环500次之后测得的数据。
对比例1和实施例2-25的锂离子电池产品同样按照上述步骤测试，测试结果总结于下表1中。
表1：对比例1和实施例1-25的二次电池的性能测试结果
Figure PCTCN2022115119-appb-000003
Figure PCTCN2022115119-appb-000004
Figure PCTCN2022115119-appb-000005
通过比较本发明实施例5与对比例1可以看出，与目前常规使用的PAA类粘接剂相比，通过在水系浆料中包含本发明的三元共聚物，可以显著抑制水系浆料的凝胶倾向，使其在静置24小时后仍具有令人满意的流动性。同时，从实施例1-7的结果可以看出，通过调节所述三元共聚物在浆料的主要成分(即正极活性物质、导电剂和粘接剂)中的比例，可以实现对于循环DCR的最优化，使得直流阻抗的增加最小化(实施例5)。
实施例8-16在实施例5的基础上另外添加了不同比例的小分子增塑剂碳酸亚乙酯(EC)，明显改善了由其制得的正极极片的脆性，消除了极片表面的轻微裂纹，使得极片具有令人满意的外观。同样，通过调节小分子增 塑剂添加的比例，可以实现对于循环DCR的最优化，使得直流阻抗的增加最小化(实施例12)。
实施例17-25在实施例12的基础上又另外添加了不同比例的碱性添加剂LiOH，明显提高了由其所制得的二次电池的克容量。通过调节LiOH的添加量，可使得可容量的增加最大化。实施例22通过加入2.0重量份的LiOH，使得克容量增加到155.8mAh/g，相比于实施例12的151.3mAh/g的可容量，取得了显著提升。
虽然已经参考实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (20)

  1. 一种水性粘接剂，其中包含至少一种三元共聚物，所述三元共聚物衍生自包括(甲基)丙烯酸、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺在内的单体，或者衍生自包括(甲基)丙烯腈、(甲基)丙烯酸C 1-C 20烷基酯以及(甲基)丙烯酰胺在内的单体，其中所述三元共聚物的玻璃化转变温度Tg为-20℃至40℃，可选地为0℃至20℃。
  2. 根据权利要求1所述的水性粘接剂，其中所述三元共聚物的重均分子量Mw为40,0000-110,0000g/mol，可选地为40,0000-80,0000g/mol，进一步可选地为45,0000-60,0000g/mol。
  3. 根据权利要求1或2所述的水性粘接剂，其中在所述三元共聚物中，各单体单元的重量比例为：(甲基)丙烯酸或(甲基)丙烯腈为50-70％，(甲基)丙烯酸C 1-C 20烷基酯为15-35％，以及(甲基)丙烯酰胺为15-35％；可选地，各单体单元的重量比例为：(甲基)丙烯酸或(甲基)丙烯腈为50-60％，(甲基)丙烯酸C 1-C 20烷基酯为20-30％，以及(甲基)丙烯酰胺为20-30％。
  4. 根据权利要求1所述的水性粘接剂，其中所述三元共聚物具有以下通式(I)或(II)的结构：
    Figure PCTCN2022115119-appb-100001
    其中，R 1彼此相同或不同地独立地为H或者甲基，
    R 2为C 1-C 20烷基，可选地为C 1-C 8烷基，进一步可选地为甲基、乙 基、正丙基、异丙基、正丁基、仲丁基、叔丁基、正戊基、正辛基、异辛基，
    x、y和z独立地为选自100-10000的整数，可选地为选自500-5000的整数。
  5. 根据权利要求1至4中任一项所述的水性粘接剂，其中所述(甲基)丙烯酸C 1-C 20烷基酯选自丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸丁酯、甲基丙烯酸异辛酯或其组合。
  6. 一种用于制备正极极片的水系浆料，其包含正极活性材料、导电剂和权利要求1至5中任一项所述的水性粘接剂，以及任选地水和分散剂，其中所述水性粘接剂的比例为0.4-3重量％，可选地为1.5-2.5重量％，进一步可选地为2-2.3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。
  7. 根据权利要求6所述的水系浆料，其中所述正极活性材料、导电剂和水性粘接剂的重量比为92-96：1-5：0.5-3，可选地为93-95：3-5：1.5-2.5，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。
  8. 根据权利要求6或7所述的水系浆料，其中所述正极活性材料选自磷酸铁锂、磷酸锰锂、磷酸钴锂、磷酸铁锰锂、锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物中的一种或多种，可选地为磷酸铁锂。
  9. 根据权利要求6至8中任一项所述的水系浆料，其中所述导电剂选自导电炭黑、超导炭黑、导电石墨、乙炔黑、科琴黑、石墨烯、碳纳米管中的一种或多种。
  10. 根据权利要求6至9中任一项所述的水系浆料，其还包含0.4-3重量％的增塑剂，可选地为0.8-2重量％，进一步可选地为1.5-1.8重量％，基 于所述正极活性材料、导电剂和水性粘接剂的总重量计。
  11. 根据权利要求10所述的水系浆料，其中所述增塑剂选自聚乙二醇(PEG)、碳酸亚乙酯(EC)、丙三醇等的一种或多种，可选地为碳酸亚乙酯。
  12. 根据权利要求6至11中任一项所述的水系浆料，其还包含0.5-3重量％的碱性添加剂，可选地为1.2-2.5重量％，进一步可选地为1.8-2.3重量％，基于所述正极活性材料、导电剂和水性粘接剂的总重量计。
  13. 根据权利要求12所述的水系浆料，其中所述碱性添加剂选自碱金属氢氧化物、碱金属碳酸盐、碱金属磷酸盐以及碱金属羧酸盐中的至少一种，可选地为锂的氢氧化物、碳酸盐、磷酸盐以及羧酸盐，进一步可选地为LiOH和Li 2CO 3。
  14. 根据权利要求6至13中任一项所述的水系浆料，其中所述分散剂选自聚酰胺类分散剂、聚(甲基)丙烯酸酯类分散剂、聚羧酸盐类分散剂、磺酸盐类分散剂、硅酸盐类分散剂、磷酸盐类分散剂、聚乙烯亚胺分散剂、含氨基聚合物及其胺盐类分散剂中的至少一种。
  15. 根据权利要求6至14中任一项所述的水系浆料，其以水性分散体的形式存在，或者以所述水性分散体经过干燥而得到的产物形式而存在。
  16. 根据权利要求6至15中任一项所述的水系浆料，其中所述水系浆料的固含量为30-75重量％，可选地为45-65重量％。
  17. 一种正极极片，其通过使用根据权利要求6至16中任一项所述的水系浆料而制备。
  18. 一种二次电池，其包含根据权利要求17所述的正极极片。
  19. 一种电池包，其包含根据权利要求18所述的二次电池。
  20. 一种用电装置，其包含根据权利要求18所述的二次电池或者根据权利要求19所述的电池包。
PCT/CN2022/115119 2022-08-26 2022-08-26 用于正极极片的水性粘接剂以及由其制备的正极极片 WO2024040572A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/115119 WO2024040572A1 (zh) 2022-08-26 2022-08-26 用于正极极片的水性粘接剂以及由其制备的正极极片

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/115119 WO2024040572A1 (zh) 2022-08-26 2022-08-26 用于正极极片的水性粘接剂以及由其制备的正极极片

Publications (1)

Publication Number Publication Date
WO2024040572A1 true WO2024040572A1 (zh) 2024-02-29

Family

ID=90012163

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/115119 WO2024040572A1 (zh) 2022-08-26 2022-08-26 用于正极极片的水性粘接剂以及由其制备的正极极片

Country Status (1)

Country Link
WO (1) WO2024040572A1 (zh)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030225183A1 (en) * 2000-07-07 2003-12-04 Universiteit Utrecht Adhesive for removable prosthesis
CN104247112A (zh) * 2012-04-13 2014-12-24 株式会社Uacj 集电体、电极结构体、非水电解质电池及蓄电零部件
CN105531854A (zh) * 2013-09-24 2016-04-27 东洋油墨Sc控股株式会社 非水二次电池用粘合剂、非水二次电池用树脂组合物、非水二次电池隔膜、非水二次电池电极以及非水二次电池
CN106220779A (zh) * 2016-08-17 2016-12-14 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
CN108352575A (zh) * 2015-11-30 2018-07-31 日本瑞翁株式会社 非水系二次电池粘接层用组合物、非水系二次电池用粘接层、层叠体以及非水系二次电池
CN112625197A (zh) * 2020-12-02 2021-04-09 惠州亿纬锂能股份有限公司 一种多嵌段粘结剂及其制备方法和用途

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030225183A1 (en) * 2000-07-07 2003-12-04 Universiteit Utrecht Adhesive for removable prosthesis
CN104247112A (zh) * 2012-04-13 2014-12-24 株式会社Uacj 集电体、电极结构体、非水电解质电池及蓄电零部件
CN105531854A (zh) * 2013-09-24 2016-04-27 东洋油墨Sc控股株式会社 非水二次电池用粘合剂、非水二次电池用树脂组合物、非水二次电池隔膜、非水二次电池电极以及非水二次电池
CN108352575A (zh) * 2015-11-30 2018-07-31 日本瑞翁株式会社 非水系二次电池粘接层用组合物、非水系二次电池用粘接层、层叠体以及非水系二次电池
CN106220779A (zh) * 2016-08-17 2016-12-14 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
CN112625197A (zh) * 2020-12-02 2021-04-09 惠州亿纬锂能股份有限公司 一种多嵌段粘结剂及其制备方法和用途

Similar Documents

Publication Publication Date Title
US11978905B2 (en) Secondary battery, apparatus containing the secondary battery, method for the preparation of the secondary battery, and binder composition
WO2023083148A1 (zh) 一种锂离子电池
CN114039097B (zh) 一种锂离子电池
WO2023087213A1 (zh) 一种电池包及其用电装置
WO2024045554A1 (zh) 粘结剂、制备方法、正极极片、二次电池及用电装置
WO2024045472A1 (zh) 分散剂、粘结剂组合物、正极浆料、二次电池、电池模块、电池包及用电装置
TWI795390B (zh) 非水電解質電池用黏合劑組成物、以及使用其之非水電解質電池用黏合劑水溶液、非水電解質電池用漿體組成物、非水電解質電池用電極、及非水電解質電池
WO2021108990A1 (zh) 二次电池及其制备方法和共聚物和装置
WO2023123087A1 (zh) 一种水系正极极片及包含该极片的二次电池及用电装置
CN113795952B (zh) 粘结剂、使用该粘结剂的电化学装置和电子设备
WO2023197807A1 (zh) 正极材料及其制备方法、复合正极材料、正极极片及二次电池
CN116666732A (zh) 一种二次电池及电子装置
WO2023141953A1 (zh) 正极浆料组合物及由其制备的正极极片、二次电池、电池模块、电池包和用电装置
WO2023283960A1 (zh) 正极极片、二次电池及其制备方法与包含该二次电池的电池模块、电池包和用电装置
KR20230170731A (ko) 양극 슬러리, 이차 전지, 전지 모듈, 전지 팩 및 전기 장치
WO2023004633A1 (zh) 一种电池、电池模块、电池包和用电装置
WO2024040572A1 (zh) 用于正极极片的水性粘接剂以及由其制备的正极极片
WO2022001429A1 (zh) 一种正极极片及含该正极极片的二次电池
CN113937250A (zh) 一种正极极片及含该正极极片的固态电池
WO2024040489A1 (zh) 功能聚合物、电极浆料、电极极片、电池及用电装置
WO2024077507A1 (zh) 粘结组合物、电极浆料、电极极片、二次电池及用电装置
CN117143545B (zh) 粘结剂及其制备方法、负极极片、电池和用电装置
WO2024113081A1 (zh) 粘结剂、极片、二次电池和用电装置
WO2024050810A1 (zh) 一种粘结剂组合物及由其制备的电极极片
WO2023245491A1 (zh) 粘结剂及其制备方法、正极浆料、正极极片、二次电池、电池模块、电池包和用电装置

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: 22956118

Country of ref document: EP

Kind code of ref document: A1