WO2022198472A1 - 粘结剂及包括该粘结剂的电化学装置 - Google Patents

粘结剂及包括该粘结剂的电化学装置 Download PDF

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WO2022198472A1
WO2022198472A1 PCT/CN2021/082559 CN2021082559W WO2022198472A1 WO 2022198472 A1 WO2022198472 A1 WO 2022198472A1 CN 2021082559 W CN2021082559 W CN 2021082559W WO 2022198472 A1 WO2022198472 A1 WO 2022198472A1
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binder
unsubstituted
substituted
mol
formula
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PCT/CN2021/082559
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English (en)
French (fr)
Inventor
胡城鑫
李娅洁
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宁德新能源科技有限公司
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Priority to PCT/CN2021/082559 priority Critical patent/WO2022198472A1/zh
Priority to EP21932101.5A priority patent/EP4310958A1/en
Priority to CN202180003987.0A priority patent/CN114207883A/zh
Publication of WO2022198472A1 publication Critical patent/WO2022198472A1/zh
Priority to US18/472,544 priority patent/US20240021829A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/30—Introducing nitrogen atoms or nitrogen-containing groups
    • C08F8/32—Introducing nitrogen atoms or nitrogen-containing groups by reaction with amines
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of secondary batteries, and in particular, to a binder and an electrochemical device including the binder.
  • the lithium-ion battery binder provides a bonding effect in the pole piece, and because it does not participate in the de-intercalation of lithium from the main material, the less the amount, the better.
  • the decrease in the dosage will inevitably lead to a decrease in the bonding effect, resulting in the release of the active main material from the current collector.
  • some alloy-type main material particles such as silicon
  • undergo a huge volume change when lithium is deintercalated and the binder with low binding effect cannot withstand the stress caused by the huge volume deformation, resulting in the failure of the inter-particle bonding and the occurrence of particles.
  • the unrestricted slip between the cells reduces the cycle life of the cell and the cycle thickness continues to increase.
  • the conventional binder completely coats the particle surface, which hinders the intercalation of lithium ions, resulting in poor charging and discharging kinetics of lithium batteries.
  • the present application proposes a binder and an electrochemical device including the binder.
  • the binder has high binding force, is helpful for desolvation of lithium ions, alleviates the hindered intercalation of lithium ions, and improves the Kinetic performance of electrochemical devices.
  • the application provides a binder, the binder is a polymer containing structural units as shown in formula I, formula II and formula III:
  • R 1 is independently selected from substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, substituted or unsubstituted C6-C20 aryl any of the bases;
  • R 2 is selected from phenolic hydroxyl groups, and the number of said phenolic hydroxyl groups is 2 to 5;
  • R is selected from any one of C, S, N, and P;
  • X is selected from any one of Li, Na, and K;
  • R 4 and R 5 are each independently selected from hydrogen atom, substituted or unsubstituted C1-C10 alkyl group, substituted or unsubstituted C2-C10 alkenyl group, substituted or unsubstituted C2-C10 alkynyl group, substituted or unsubstituted C2-C10 alkynyl group, substituted or unsubstituted C1-C10 alkyl group any one of the C6-C20 aryl groups;
  • n1, n2, and n3 are each independently an integer greater than zero.
  • R in the structural unit shown in the formula I 2 is selected from
  • the molar proportion of the structural unit represented by formula I in the binder is 5 mol % to 30 mol %;
  • the molar proportion of the structural unit represented by formula II in the binder is 10 mol % to 60 mol %;
  • the molar proportion of the structural unit represented by the formula III in the binder is 35 mol % to 55 mol %.
  • the binder further includes a functional monomer in an amount of 0wt% to 1wt%, and the functional monomer includes acrylamide derivative monomers , at least one of acrylic derivative monomers.
  • the acrylamide derivative monomers include acrylamide, N-methacrylamide, N-ethylacrylamide, N-butylacrylamide or NN- At least one of methylenebisacryloyl.
  • the acrylic derivative monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, acrylic acid Cyclohexyl ester, isobornyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, vinyl acetate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate At least one of ester, cyclohexyl methacrylate, isobornyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate or polyoxyethylene diacrylate .
  • the pH value of the binder is 3 to 12.
  • the binder satisfies at least one of the following characteristics a to c:
  • the glass transition temperature of the binder is 80°C to 200°C;
  • the viscosity of the binder is 1000mPa ⁇ s to 20000mPa ⁇ s;
  • the molecular weight of the binder is between 1,000 and 5,000,000.
  • the binder further includes a solvent, and the solvent is an organic solvent or water.
  • the binder further includes an additive, and the additive includes at least one of a dispersing agent, a leveling agent, a wetting agent, a defoaming agent, and a softening agent .
  • the binder is applied to the negative electrode and/or the positive electrode of a lithium ion battery.
  • the embodiments of the present application provide an electrochemical device, including a positive pole piece, a negative pole piece, a separator, and an electrolyte, at least one of the positive pole piece, the negative pole piece, and the separator Contains the binder described in the first aspect.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the mass ratio of the binder to the negative electrode active material layer is 3.0 wt % to 6.0 wt%.
  • the present application at least has the following beneficial effects:
  • the benzene ring structure can form a ⁇ conjugated force with graphite
  • the phenolic hydroxyl group and the cyano group can have a strong polar interaction force with the metal current collector
  • the salted anion group can provide more
  • the migration of lithium ions can also compete with the solvent around the lithium ions, help the desolvation of lithium ions, alleviate the hindered intercalation of lithium ions, and improve the kinetic performance of the electrochemical device.
  • FIG. 1a is a schematic diagram of the adhesion test of the adhesive of Example 3 of the application.
  • Figure 1b is a schematic diagram of the adhesive force test of the adhesive of Comparative Example 1 of the application.
  • FIG. 2 is a schematic diagram of the battery charging and discharging test results of Example 3 and Comparative Example 1 of the present application.
  • any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with any other lower limit to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range.
  • every point or single value between the endpoints of a range is included within the range, even if not expressly recited.
  • each point or single value may serve as its own 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 embodiments of the present application provide a binder whose structure is shown in formula A:
  • the binder is a polymer containing structural units as shown in formula I, formula II and formula III:
  • R 1 is independently selected from substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, substituted or unsubstituted C6-C20 aryl any of the bases;
  • R 2 is selected from phenolic hydroxyl groups, and the number of said phenolic hydroxyl groups is 2 to 5;
  • R is selected from any one of C, S, N, and P;
  • X is selected from any one of Li, Na, and K;
  • R 4 and R 5 are each independently selected from hydrogen atom, substituted or unsubstituted C1-C10 alkyl group, substituted or unsubstituted C2-C10 alkenyl group, substituted or unsubstituted C2-C10 alkynyl group, substituted or unsubstituted C2-C10 alkynyl group, substituted or unsubstituted C1-C10 alkyl group any one of the C6-C20 aryl groups;
  • n1, n2, and n3 are each independently an integer greater than zero.
  • the benzene ring structure can form a ⁇ conjugated force with graphite
  • the phenolic hydroxyl group and the cyano group can have a strong polar interaction force with the metal current collector
  • the salted anion group can provide more
  • the migration of lithium ions can also compete with the solvent around the lithium ions, help the desolvation of lithium ions, alleviate the hindered intercalation of lithium ions, and improve the kinetic performance of the electrochemical device.
  • the C1-C10 alkyl group may be a chain alkyl group or a cyclic alkyl group, and the chain alkyl group may be a straight chain alkyl group or a branched chain alkyl group.
  • Hydrogen can be further substituted by alkyl.
  • the preferable lower limit of the number of carbon atoms in the C1-C10 alkyl group is 1, 2, 3, and 4, and the preferable upper limit is 5, 6, 8, and 10.
  • C1-C10 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl yl, neopentyl, hexyl, 2-methyl-pentyl, 3-methyl-pentyl, 1,1,2-trimethyl-propyl, 3,3-dimethyl-butyl, heptyl , 2-heptyl, 3-heptyl, 2-methylhexyl, 3-methylhexyl, isoheptyl, octyl, nonyl, decyl.
  • C1-C10 alkyl group contains an oxygen atom
  • it can be a C1-C10 alkoxy group.
  • C1-C6 alkoxy is selected; further preferably, C1-C4 alkoxy is selected.
  • Specific examples of C1-C10 alkoxy include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, n-pentoxy Oxy, isopentyloxy, cyclopentyloxy, cyclohexyloxy.
  • the C2-C10 alkenyl group can be a cyclic alkenyl group or a chain alkenyl group, and the chain alkenyl group can also be a straight chain alkenyl group or a branched chain alkenyl group.
  • the number of double bonds in the C2-C10 alkenyl group is preferably one.
  • the preferred lower limit of the number of carbon atoms in the C2-C10 alkenyl group is 2, 3, 4, and 5, and the preferred upper limit is 3, 4, 5, 6, 8, and 10.
  • C2-C6 alkenyl is selected; further preferably, C2-C5 alkenyl is selected.
  • C2-C10 alkenyl group examples include a vinyl group, an allyl group, an isopropenyl group, a pentenyl group, a cyclohexenyl group, a cycloheptenyl group, and a cyclooctenyl group.
  • the C2-C10 alkynyl group can be a cyclic alkynyl group or a chain alkynyl group, and the chain alkynyl group can also be a straight-chain alkynyl group or a branched-chain alkynyl group.
  • the number of triple bonds in the C2-C10 alkynyl group is preferably one.
  • the preferred lower limit of the number of carbon atoms in the C2-C10 alkynyl group is 2, 3, 4, and 5, and the preferred upper limit is 3, 4, 5, 6, 8, and 10.
  • C2-C10 alkynyl group examples include ethynyl, propargyl, isopropynyl, pentynyl, cyclohexynyl, and cycloheptynyl.
  • the C6-C20 aryl group can be phenyl, phenylalkyl, biphenyl, fused-ring aromatic hydrocarbon groups (such as naphthyl, anthracenyl, phenanthrenyl), and biphenyl and fused-ring aromatic hydrocarbon groups can be further alkyl or alkene base substitution.
  • Specific examples of the C6-C20 aryl group include a phenyl group, a benzyl group, a biphenyl group, a p-tolyl group, an o-tolyl group, a m-tolyl group, and a naphthyl group.
  • the substituent is selected from one or more of halogen atoms, preferably, the substituent is selected from fluorine atom, chlorine atom and bromine atom.
  • the structural unit represented by formula I is a phenolic hydroxyl group-containing structure, wherein R 2 is selected from phenolic hydroxyl groups and the number of the phenolic hydroxyl groups is 2 to 5.
  • R 2 is selected from any of the following groups:
  • the molar proportion of the structural unit represented by formula I in the binder is 5 mol % to 30 mol %, specifically 5 mol %, 7 mol %, 9 mol %, 10 mol %, 12 mol % %, 15 mol %, 18 mol %, 20 mol %, 25 mol %, 28 mol % or 30 mol %, etc., of course, other values within the above range can also be used, which are not limited here.
  • the molar proportion of the structural unit represented by formula I when the molar proportion of the structural unit represented by formula I is lower than 5 mol% or higher than 30 mol%, the viscosity of the binder decreases, and the negative electrode active material or the positive electrode active material is easily removed from the battery during the cycle of the battery. The current collector falls off, and the capacity retention rate of the battery decreases.
  • the molar ratio of the structural unit represented by formula I in the binder is 10 mol % to 25 mol %, and further preferably, the molar ratio of the structural unit represented by formula I in the binder is 15 mol% to 20 mol%.
  • the structural unit represented by formula II is an anion-containing group XO m R 3 structure, wherein R 3 can be any one of C, S, N, and P elements; the oxygen number m can be 1, 2, 3 or 4, X can be Li, Na, K and other elements.
  • the anionic group may be lithium carboxylate, lithium sulfonate, lithium phosphate and the like. Understandably, the anionic group can not only carry more lithium ions, increase the number of lithium ions, but also compete with the surrounding solvent of lithium ions, help lithium ions desolvate, alleviate the hindered intercalation of lithium ions, and improve the power of electrochemical devices. academic performance.
  • the molar proportion of the structural unit represented by formula II in the binder is 10 mol % to 60 mol %, specifically 10 mol %, 15 mol %, 20 mol %, 25 mol %, 30 mol % %, 35 mol %, 40 mol %, 45 mol %, 50 mol %, 55 mol % or 60 mol %, etc., of course, other values within the above range can also be used, which are not limited herein.
  • the binder can provide more lithium ions during the battery cycle, It can also compete with the solvent around the lithium ion, help the desolvation of the lithium ion, relieve the hindered intercalation of the lithium ion, and improve the kinetic performance of the electrochemical device.
  • the molar ratio of the structural unit represented by formula II in the binder is 15 mol % to 45 mol %, and further preferably, the molar ratio of the structural unit represented by formula II in the binder is 20 mol% to 30 mol%.
  • the structural unit shown in the formula III is a cyano group-containing structure, and the structure shown in the formula III
  • the molar proportion of the structural unit represented by formula III in the binder is 35mol% to 55mol%, specifically 35mol%, 40mol%, 45mol%, 50mol% or 55mol% %, etc., of course, can also be other values within the above range, which are not limited here. It can be understood that with the increase of the structural unit represented by the formula III in the binder, that is, the increase of the cyano group in the binder, the viscosity of the binder gradually increases, and the structure of the active material layer on the current collector is stable. It can improve the capacity retention rate of the battery.
  • the molar ratio of the structural unit represented by formula III in the binder is greater than 60%, the viscosity of the binder is too large to be water-soluble, which reduces the convenience of use.
  • the molar ratio of the structural unit represented by formula III in the binder is 40 mol% to 55 mol%, and further preferably, the molar ratio of the structural unit represented by formula III in the binder is 50 mol% to 55 mol%.
  • the binder further includes functional monomers with a mass ratio of 0wt% to 1wt%, and the functional monomers include acrylamide derivative monomers, acrylic acid derivatives at least one of the monomers.
  • Functional monomers can improve the mechanical properties of the binder, improve the solvent resistance, water resistance, gloss and color retention, and acid and alkali resistance of the binder.
  • the acrylamide derivative monomers include acrylamide, N-methacrylamide, N-ethylacrylamide, N-butylacrylamide or NN-methylenebisacrylamide at least one of acyl.
  • the acrylic derivative monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, acrylic acid Isobornyl, hydroxyethyl acrylate, hydroxypropyl acrylate, vinyl acetate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid At least one of cyclohexyl ester, isobornyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate or polyoxyethylene diacrylate.
  • the pH value of the binder is 3 to 12, specifically 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, etc., of course, it can also be Other values within the above range are not limited here.
  • the pH of the binder is 6 to 10.
  • the glass transition temperature of the binder is 80°C to 200°C, specifically 80°C, 90°C, 100°C, 110°C, 120°C, 140°C, 150°C, 160°C, 180°C, or 200°C, etc., of course, other values within the above-mentioned range are also possible, which are not limited here.
  • the glass transition temperature of the binder is too high, the binder is hard and brittle, and the pole piece is cold-pressed and released; the glass transition temperature of the binder is too low, and it is in a rubbery state at room temperature, which is difficult to maintain the bonding of the material particles in the pole piece. Effect.
  • the viscosity of the binder is 1000mPa ⁇ s to 20000mPa ⁇ s, specifically 1000mPa ⁇ s, 3000mPa ⁇ s, 5000mPa ⁇ s, 8000 mPa ⁇ s, 10000 mPa ⁇ s, 13000 mPa ⁇ s, 15000 mPa ⁇ s, 18000 mPa ⁇ s, or 20000 mPa ⁇ s, etc., of course, other values within the above range are also possible, which are not limited here.
  • Monomer composition adjustment affects the viscosity of the binder, which affects the slurry stirring and coating process.
  • the molecular weight of the binder is between 1,000 and 5,000,000, specifically 1,000, 5,000, 10,000, 100,000, 500,000, 1 million, 3 million, or 5 million, etc. , and of course other values within the above range, which are not limited here.
  • the molecular weight of the binder affects the viscosity of the binder, which affects the slurry stirring and coating process. If the viscosity is too large, the stirring power consumption is large, and the slurry is difficult to level during the coating process; if the viscosity is too small, the fluidity of the coating slurry is good. Difficulty in leveling and too good fluidity will lead to differences in coating, serious fluctuations in coating weight, and abnormal use of the pole piece.
  • the binder further includes a solvent
  • the solvent is an organic solvent or water.
  • the present invention also relates to a preparation method of the binder: the binder is prepared by the method of emulsion polymerization of the structural monomer of formula I, the structural monomer of formula II, and the structural monomer of formula III.
  • the binder further includes an additive, and the additive includes at least one of a dispersing agent, a leveling agent, a wetting agent, a defoaming agent, and a softening agent.
  • the binder is applied to the negative electrode and/or the positive electrode of the lithium ion battery.
  • the embodiments of the present application further provide an electrochemical device, comprising a positive electrode piece, a negative electrode piece, a separator, and an electrolyte, at least one of the positive electrode piece, the negative electrode piece, and the separator One containing the binder described in the first aspect above.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the mass ratio of the binder to the negative electrode active material layer is 3.0wt% to 6.0wt%, preferably 4.5 wt % to 5.5 wt %, more preferably 5 wt %.
  • the above-mentioned positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector.
  • the positive electrode active material includes at least one of lithium cobalt oxide (LiCoO 2 ), lithium nickel manganese cobalt ternary material, lithium iron phosphate, lithium manganese iron phosphate, and lithium manganate.
  • LiCoO 2 lithium cobalt oxide
  • nickel manganese cobalt ternary material lithium nickel manganese cobalt ternary material
  • lithium iron phosphate lithium manganese iron phosphate
  • lithium manganate lithium manganate
  • the positive electrode current collector includes, but is not limited to, aluminum foil.
  • the above-mentioned negative electrode pole piece includes a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.
  • the negative electrode active material includes at least one of silicon negative electrode material, silicon oxygen negative electrode material, silicon carbon negative electrode material, and graphite negative electrode material.
  • the negative electrode current collector includes, but is not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, foamed copper or a polymer substrate coated with conductive metal.
  • the electrochemical device further includes an electrolyte, and the electrolyte includes an organic solvent, a lithium salt and an additive.
  • the organic solvent of the electrolytic solution according to the present application may be any organic solvent known in the prior art that can be used as a solvent of the electrolytic solution.
  • the electrolyte used in the electrolyte solution according to the present application is not limited, and it may be any electrolyte known in the prior art.
  • the additive for the electrolyte according to the present application may be any additive known in the art as an additive for the electrolyte.
  • the organic solvent includes, but is not limited to: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate.
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • the lithium salts include, but are not limited to: lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2 (LiTFSI), Lithium Bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), Lithium Bisoxalate Borate LiB(C 2 O 4 ) 2 (LiBOB) ) or lithium difluorooxalate borate LiBF 2 (C 2 O 4 ) (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiPFSI bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO
  • the electrochemical device of the present application includes, but is not limited to: all kinds of primary batteries, secondary batteries, fuel cells, solar cells or capacitors.
  • the electrochemical device is a lithium secondary battery, wherein the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion secondary battery polymer secondary battery.
  • lithium ion batteries The preparation of lithium ion batteries is described below by taking lithium ion batteries as an example and in conjunction with specific embodiments. Those skilled in the art will understand that the preparation methods described in this application are only examples, and any other suitable preparation methods are included in the scope of this application. within the range.
  • solution A 1.5 parts of ammonium persulfate, 15 parts of deionized water, and 15 parts of acrylonitrile are fully stirred to obtain solution A, which is stored at 2°C to 8°C until use.
  • the negative electrode active material, conductive carbon black and polymer are added with deionized water according to the mass ratio of 80:10:10, stirred into a slurry, coated with a scraper to form a coating with a thickness of 100um, and dried in a vacuum drying oven at 85°C for 12 hours.
  • using a punching machine in a dry environment to cut into 1cm diameter discs, in a glove box with a metal lithium sheet as the counter electrode select the ceglard composite membrane for the separator, and add electrolyte to assemble a button battery.
  • Use the LAND series battery test to test the charge and discharge of the battery to test its charge and discharge performance.
  • the negative electrode active material, conductive carbon black and polymer were added with deionized water according to the mass ratio of 80:10:10, stirred into a slurry, coated with a scraper to form a coating with a thickness of 50um, and dried in a vacuum drying oven at 85°C for 12 hours. . Cut out a spline with a size of 2cm ⁇ 10cm, align the coated surface of the spline on a double-sided tape (3M VBH4920) with a width of 2cm, and roll it back and forth with a 2kg roller for 3 to 4 times.
  • the splines were obtained by calculating the average tensile force after stretching 50mm through a universal material testing machine, a 180° uniaxial tensile mode, a clamp speed of 50mm/min.
  • the adhesive glue solution was dried at 70 °C for 24 hours to obtain a film, which was taken for testing.
  • the test method refers to the national standard GB/T 13464-2008. Test temperature range: -50 ⁇ 200°C, heating rate 10°C/min.
  • the solid content of the configured binder glue is 4%, and the binder glue solution is taken for testing.
  • the test method refers to the national standard GB/T 10247-2008 vertebral-plate type rotational viscometer, the constant test temperature is 25°C, and the constant shear rate is 0.1 1/s.
  • the molar ratio of the structural unit represented by formula III in the binder is 40 mol% to 55 mol%, and further preferably, the molar ratio of the structural unit represented by formula III in the binder is 50 mol% to 55 mol%.
  • the molar ratio of the structural unit represented by formula II in the binder is 15 mol % to 45 mol %, and further preferably, the molar ratio of the structural unit represented by formula II in the binder is 20 mol% to 30 mol%.
  • the negative active materials in the negative pole pieces are different, but have little effect on the adhesion of the pole pieces.
  • the binder is suitable for silicon-oxygen negative electrode materials and silicon carbon negative electrode materials. , silicon anode material or graphite anode material.

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Abstract

一种粘结剂及包括该粘结剂的电化学装置，粘结剂为含有如式I、式II及式III所示的结构单元的聚合物，其中，R 1独立地选自取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；R 2选自酚羟基，且酚羟基的数量为2至5；R 3选自C、S、N、P中的任意一种；X选自Li、Na、K中的任意一种；R 4、R 5各自独立地选自氢原子、取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；n1、n2、n3各自独立的为大于零的整数。该粘结剂具有较高粘结力，有助于锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。

Description

粘结剂及包括该粘结剂的电化学装置 技术领域
本申请涉及二次电池领域，具体讲，涉及一种粘结剂及包括该粘结剂的电化学装置。
背景技术
目前，锂离子电池粘结剂在极片中提供粘结效果，因不参与主材脱嵌锂，所以用量越少越好。但用量下降必然导致粘结效果下降，导致活性主材从集流体上脱膜。此外，一些合金型主材颗粒(如硅)，在脱嵌锂时发生巨大体积变化，低粘结效果的粘结剂无法承受巨大体积形变带来的应力，导致颗粒间粘结失效，发生颗粒间无限制滑移，使得电芯循环寿命下降，循环厚度持续增加。
常规粘结剂因完全包覆颗粒表面导致锂离子嵌入受阻，导致锂电池充放电动力学变差。
申请内容
鉴于此，本申请提出了一种粘结剂及包括该粘结剂的电化学装置，该粘结剂具有较高粘结力，有助于锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。
第一方面，本申请提供一种粘结剂，所述粘结剂为含有如式I、式II及式III所示的结构单元的聚合物：
Figure PCTCN2021082559-appb-000001
其中，R 1独立地选自取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；
R 2选自酚羟基，且所述酚羟基的数量为2至5；
R 3选自C、S、N、P中的任意一种；X选自Li、Na、K中的任意一种；
R 4、R 5各自独立地选自氢原子、取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；
n1、n2、n3各自独立的为大于零的整数。
结合第一方面，在一种可行的实施方式中，所述式I所示的结构单元中的R 2选自
Figure PCTCN2021082559-appb-000002
其中，
Figure PCTCN2021082559-appb-000003
表示与相邻原子的结合位点。
结合第一方面，在一种可行的实施方式中，
式I所示的结构单元在所述粘结剂中的摩尔占比为5mol％至30mol％；
式II所示的结构单元在所述粘结剂中的摩尔占比为10mol％至60mol％；
式III所示的结构单元在所述粘结剂中的摩尔占比为35mol％至55mol％。
结合第一方面，在一种可行的实施方式中，所述粘结剂还包括质量占比为0wt％至1wt％的功能性单体，所述功能性单体包括丙烯酰胺类衍生物单体、丙烯酸类衍生物单体中的至少一种。
结合第一方面，在一种可行的实施方式中，所述丙烯酰胺类衍生物单体包括丙烯酰胺，N-甲基丙烯酰胺、N-乙基丙烯酰胺、N-丁基丙烯酰胺或NN-亚甲基双丙烯酰中的至少一种。
结合第一方面，在一种可行的实施方式中，所述丙烯酸类衍生物单体包括丙烯酸甲酯、丙烯酸乙酯、丙烯酸正丁酯、丙烯酸叔丁酯、丙烯酸2-乙基己酯、丙烯酸环己基酯、丙烯酸异冰片酯、丙烯酸羟乙酯、丙烯酸羟丙酯、乙酸乙烯酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸正丁酯、甲基丙烯酸2-乙基己酯、甲基丙烯酸环己基酯、甲基丙烯酸异冰片酯、甲基丙烯酸-羟乙酯、甲基丙烯酸羟丙酯、甲基丙烯酸环氧丙酯或聚氧乙烯二丙烯酸酯中的至少一种。
结合第一方面，在一种可行的实施方式中，所述粘结剂的pH值为3至12。
结合第一方面，在一种可行的实施方式中，所述粘结剂满足以下特征a至c中的至少一种：
a.所述粘结剂的玻璃化转变温度为80℃至200℃；
b.所述粘结剂的固体含量为4％时，所述粘结剂的粘度为1000mPa·s至20000mPa·s；
c.所述粘结剂的分子量在1000至500万之间。
结合第一方面，在一种可行的实施方式中，所述粘结剂还包括溶剂，所述溶剂为有机溶剂或水。
结合第一方面，在一种可行的实施方式中，所述粘结剂还包括添加剂，所述添加 剂包括分散剂、流平剂、润湿剂、消泡剂、增柔剂中的至少一种。
结合第一方面，在一种可行的实施方式中，所述粘结剂应用于锂离子电池的负极和/或正极。
第二方面，本申请实施例提供一种电化学装置，包括正极极片、负极极片、隔离膜和电解液，所述正极极片、所述负极极片、所述隔离膜中至少之一含有上述第一方面所述的粘结剂。
结合第二方面，在一种可行的实施方式中，所述负极极片包括负极集流体和负极活性物质层，所述粘结剂占所述负极活性物质层的质量占比为3.0wt％至6.0wt％。
相对于现有技术，本申请至少具有以下有益效果：
本申请提供的粘结剂，其中的苯环结构可与石墨形成ππ共轭作用力，酚羟基、氰基可与金属集流体具有强极性作用力，盐化的阴离子基团能提供更多锂离子迁移，又能与锂离子周围溶剂竞争，帮助锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。
附图说明
图1a为本申请实施例3的粘结剂的粘结力测试示意图；
图1b为本申请对比例1的粘结剂的粘结力测试示意图；
图2为本申请实施例3与对比例1的电池充放电测试结果示意图。
具体实施方式
以下所述是本申请实施例的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请实施例原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本申请实施例的保护范围。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何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，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的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。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或多种”中“多种”的含义是两个以上。
本申请的上述申请内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
第一方面，本申请实施例提供了一种粘结剂，其结构如式A所示：
Figure PCTCN2021082559-appb-000004
具体地，所述粘结剂为含有如式I、式II及式III所示的结构单元的聚合物：
Figure PCTCN2021082559-appb-000005
其中，R 1独立地选自取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；
R 2选自酚羟基，且所述酚羟基的数量为2至5；
R 3选自C、S、N、P中的任意一种；X选自Li、Na、K中的任意一种；
R 4、R 5各自独立地选自氢原子、取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；
n1、n2、n3各自独立的为大于零的整数。
本申请提供的粘结剂，其中的苯环结构可与石墨形成ππ共轭作用力，酚羟基、氰基可与金属集流体具有强极性作用力，盐化的阴离子基团能提供更多锂离子迁移，又能与锂离子周围溶剂竞争，帮助锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。
可选地，C1-C10烷基可为链状烷基，也可为环状烷基，链状烷基又可为直链烷基或支链烷基，位于环状烷基的环上的氢还可进一步被烷基取代。C1-C10烷基中碳原子数优选的下限值为1、2、3、4，优选的上限值为5、6、8、10。作为C1-C10烷基 的实例，具体可以举出：甲基、乙基、正丙基、异丙基、正丁基、异丁基、仲丁基、叔丁基、正戊基、异戊基、新戊基、己基、2-甲基-戊基、3-甲基-戊基、1,1,2-三甲基-丙基、3,3-二甲基-丁基、庚基、2-庚基、3-庚基、2-甲基己基、3-甲基己基、异庚基、辛基、壬基、癸基。
当前述所提到的C1-C10烷基中含有氧原子时，可为C1-C10烷氧基。优选地，选择C1-C6烷氧基；进一步优选地，选择C1-C4烷氧基。作为C1-C10烷氧基的实例，具体可以举出：甲氧基、乙氧基、正丙氧基、异丙氧基、正丁氧基、仲丁氧基、叔丁氧基、正戊氧基、异戊氧基、环戊氧基、环己氧基。
C2-C10烯基可为环状烯基，也可为链状烯基，链状烯基又可为直链烯基或支链烯基。另外，C2-C10烯基中双键的个数优选为1个。C2-C10烯基中碳原子数优选的下限值为2、3、4、5，优选的上限值为3、4、5、6、8、10。优选地，选择C2-C6烯基；进一步优选地，选择C2-C5烯基。作为C2-C10烯基的实例，具体可以举出：乙烯基、烯丙基、异丙烯基、戊烯基、环己烯基、环庚烯基、环辛烯基。
C2-C10炔基可为环状炔基，也可为链状炔基，链状炔基又可为直链炔基或支链炔基。另外，C2-C10炔基中三键的个数优选为1个。C2-C10炔基中碳原子数优选的下限值为2、3、4、5，优选的上限值为3、4、5、6、8、10。作为C2-C10炔基的实例，具体可以举出：乙炔基、炔丙基、异丙炔基、戊炔基、环己炔基、环庚炔基。
C6-C20芳基可为苯基、苯烷基、联苯基、稠环芳烃基(例如萘基、蒽基、菲基)，联苯基和稠环芳烃基还可进一步被烷基或烯基取代。作为C6-C20芳基的实例，具体可以举出：苯基、苄基、联苯基、对甲苯基、邻甲苯基、间甲苯基、萘基。
其中，取代基选自卤素原子中的一种或几种，优选地，取代基选自氟原子、氯原子及溴原子。
作为本申请可选的技术方案，式I所示结构单元为含酚羟基结构，其中，R 2选自酚羟基且所述酚羟基的数量为2至5。可选地R 2选自以下基团中的任意一种：
Figure PCTCN2021082559-appb-000006
其中，
Figure PCTCN2021082559-appb-000007
表示与相邻原子的结合位点。
作为本申请可选的技术方案，式I所示的结构单元在所述粘结剂中的摩尔占比为5mol％至30mol％，具体可以是5mol％、7mol％、9mol％、10mol％、12mol％、15mol％、18mol％、20mol％、25mol％、28mol％或30mol％等等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，当式I所示的结构单元的摩尔占比低于5mol％或高于30mol％时，粘结剂的粘力下降，电池在循环过程中，负极活性材料或正极活性材料容易从集流体上脱落，电池的容量保持率下降。优选地，式I所示的结构单元在所述粘结剂中的摩尔占比为10mol％至25mol％，进一步优选地，式I所示的结构单元在所述粘结剂中的摩尔占比为15mol％至20mol％。
作为本申请可选的技术方案，式II所示结构单元为含阴离子基团XO mR 3结构，其中R 3可以是C、S、N、P元素中的任意一种；氧数量m可以是1、2、3或4，X可以 是Li、Na、K等元素。优选地，阴离子基团可以是羧酸锂、磺酸锂、磷酸锂等。可以理解地，阴离子基团既能携带更多的锂离子，提高锂离子迁移数，又能与锂离子周围溶剂竞争，帮助锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。
作为本申请可选的技术方案，式II所示的结构单元在所述粘结剂中的摩尔占比为10mol％至60mol％，具体可以是10mol％、15mol％、20mol％、25mol％、30mol％、35mol％、40mol％、45mol％、50mol％、55mol％或60mol％等等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，随着粘结剂中的式II所示的结构单元的增多，即粘结剂中的盐化的阴离子基团增加，粘结剂在电池循环过程中能提供更多锂离子，又能与锂离子周围溶剂竞争，帮助锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。优选地，式II所示的结构单元在所述粘结剂中的摩尔占比为15mol％至45mol％，进一步优选地，式II所示的结构单元在所述粘结剂中的摩尔占比为20mol％至30mol％。
作为本申请可选的技术方案，式III所示结构单元为含氰基结构，所述式III所示
Figure PCTCN2021082559-appb-000008
作为本申请可选的技术方案，式III所示的结构单元在所述粘结剂中的摩尔占比为35mol％至55mol％，具体可以是35mol％、40mol％、45mol％、50mol％或55mol％等等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，随着粘结剂中的式III所示的结构单元的增多，即粘结剂中的氰基增加，粘结剂的粘度逐渐增大，集流体上的活性材料层的结构稳定性增大，可以提高电池的容量保持率。但是当式III所示的结构单元在所述粘结剂中的摩尔占比大于60％时，粘结剂的粘度过大，无法水溶，降低其的使用便捷性。优选地，式III所示的结构单元在所述粘结剂中的摩尔占比为40mol％至55mol％，进一步优选地，式III所示的结构单元在所述粘结剂中的摩尔占比为50mol％至55mol％。
作为本申请可选的技术方案，所述粘结剂还包括质量占比为0wt％至1wt％的功能性单体，所述功能性单体包括丙烯酰胺类衍生物单体、丙烯酸类衍生物单体中的至少一种。功能性单体能够改善粘结剂力学性能，改善粘结剂耐溶剂性、耐水性、保光保色性及耐酸碱性。
作为本申请可选的技术方案，所述丙烯酰胺类衍生物单体包括丙烯酰胺，N-甲基丙烯酰胺、N-乙基丙烯酰胺、N-丁基丙烯酰胺或NN-亚甲基双丙烯酰中的至少一种。
作为本申请可选的技术方案，所述丙烯酸类衍生物单体包括丙烯酸甲酯、丙烯酸乙酯、丙烯酸正丁酯、丙烯酸叔丁酯、丙烯酸2-乙基己酯、丙烯酸环己基酯、丙烯酸异冰片酯、丙烯酸羟乙酯、丙烯酸羟丙酯、乙酸乙烯酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸正丁酯、甲基丙烯酸2-乙基己酯、甲基丙烯酸环己基酯、甲基丙烯酸异冰片酯、甲基丙烯酸-羟乙酯、甲基丙烯酸羟丙酯、甲基丙烯酸环氧丙酯或聚氧乙烯二丙烯酸酯中的至少一种。
作为本申请可选的技术方案，所述粘结剂的pH值为3至12，具体可以是3、4、5、6、7、8、9、10、11或12等，当然也可以是上述范围内的其他值，在此不做限定。优选地，所述粘结剂的pH值为6至10。
作为本申请可选的技术方案，所述粘结剂的玻璃化转变温度为80℃至200℃，具体可以是80℃、90℃、100℃、110℃、120℃、140℃、150℃、160℃、180℃或200℃等，当然也可以是上述范围内的其他值，在此不做限定。粘结剂的玻璃化温度过高，粘结剂硬而脆，极片冷压脱膜；粘结剂的玻璃化温度过低，室温下呈橡胶态，难以维持极片中材料颗粒的粘结效果。
作为本申请可选的技术方案，所述粘结剂的固体含量为4％时，所述粘结剂的粘度为1000mPa·s至20000mPa·s，具体可以是1000mPa·s、3000mPa·s、5000mPa·s、8000mPa·s、10000mPa·s、13000mPa·s、15000mPa·s、18000mPa·s或20000mPa·s等，当然也可以是上述范围内的其他值，在此不做限定。单体组分调节会影响粘结剂的粘度，粘度会影响浆料搅拌和涂布过程。粘度过大，搅拌消耗功率大，涂布过程浆料难以流平；粘度过小，涂布浆料流动性好。难以流平及流动性过好均会导致涂布差异化，涂布重量波动严重，极片无法正常使用。
作为本申请可选的技术方案，所述粘结剂的分子量在1000至500万之间，具体可以是1000、5000、1万、10万、50万、100万、300万或500万等等，当然也可以是上述范围内的其他值，在此不做限定。粘结剂分子量会影响粘结剂的粘度，粘度会影响浆料搅拌和涂布过程。粘度过大，搅拌消耗功率大，涂布过程浆料难以流平；粘度过小，涂布浆料流动性好。难以流平及流动性过好均会导致涂布差异化，涂布重量波动严重，极片无法正常使用。
作为本申请可选的技术方案，所述粘结剂还包括溶剂，所述溶剂为有机溶剂或水。
本发明还涉及该粘结剂的制备方法：将式I结构单体、式II结构单体、式III结构单体通过乳液聚合的方法，制备得到所述粘结剂。
作为本申请可选的技术方案，所述粘结剂还包括添加剂，所述添加剂包括分散剂、流平剂、润湿剂、消泡剂、增柔剂中的至少一种。
作为本申请可选的技术方案，所述粘结剂应用于锂离子电池的负极和/或正极。
第二方面，本申请实施例还提供一种电化学装置，包括正极极片、负极极片、隔离膜和电解液，所述正极极片、所述负极极片、所述隔离膜中至少之一含有上述第一方面所述的粘结剂。
作为本申请可选的技术方案，所述负极极片包括负极集流体和负极活性物质层，所述粘结剂占所述负极活性物质层的质量占比为3.0wt％至6.0wt％，优选为4.5wt％至5.5wt％，更优选为5wt％。
作为本申请可选的技术方案，上述正极极片包括正极集流体和位于正极集流体上的正极活性材料层。
作为本申请可选的技术方案，正极活性材料包括钴酸锂(LiCoO 2)、锂镍锰钴三元材料、磷酸铁锂、磷酸锰铁锂、锰酸锂中的至少一种。
作为本申请可选的技术方案，正极集流体包括，但不限于：铝箔。
作为本申请可选的技术方案，上述负极极片包括负极集流体和位于负极集流体上 的负极活性材料层。
作为本申请可选的技术方案，负极活性材料包括硅负极材料、硅氧负极材料、硅碳负极材料、石墨负极材料中的至少一种。
作为本申请可选的技术方案，负极集流体包括，但不限于：铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或覆有导电金属的聚合物基底。
作为本申请可选的技术方案，电化学装置还包括电解液，所述电解液包括有机溶剂、锂盐和添加剂。
根据本申请的电解液的有机溶剂可为现有技术中已知的任何可作为电解液的溶剂的有机溶剂。根据本申请的电解液中使用的电解质没有限制，其可为现有技术中已知的任何电解质。根据本申请的电解液的添加剂可为现有技术中已知的任何可作为电解液添加剂的添加剂。
在具体实施例中，所述有机溶剂包括，但不限于：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚丙酯或丙酸乙酯。
在具体实施例中，所述锂盐包括有机锂盐或无机锂盐中的至少一种。
在具体实施例中，所述锂盐包括，但不限于：六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)。
作为本申请可选的技术方案，本申请的电化学装置包括，但不限于：所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容。
在具体实施例中，所述电化学装置是锂二次电池，其中，锂二次电池包括，但不限于：锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
下面以锂离子电池为例并且结合具体的实施例说明锂离子电池的制备，本领域的技术人员将理解，本申请中描述的制备方法仅是实例，其他任何合适的制备方法均在本申请的范围内。
一、粘结剂的制备
将1.5份过硫酸铵、15份去离子水、15份丙烯腈，充分搅拌均匀，得到溶液A，并置于2℃～8℃下保存待使用。
在三口瓶中加入30份丙烯酸锂、40份丙烯腈、15份甲基丙烯酸缩水甘油酯、235份去离子水，搅拌均匀；水浴锅升温至70℃，往三口瓶中持续通入氩气以排尽空气，待三口瓶中温度升至70℃后，以0.125ml/min速度滴加溶液A，搅拌速度400rpm反应6h，得到无色透明溶液；
最后将15份盐酸多巴胺加入到上述无色透明溶液中，惰性气体保护，在80℃下，100rpm搅拌5h，反应得到粘结剂，所述粘结剂的分子量为1000至500万。
根据上述方法制得的实施例1至33(即表中的S1至S33)的粘结剂及对比例1至3(即表中的D1至D3)的粘结剂，配比参数见表1所示。
表1
Figure PCTCN2021082559-appb-000009
Figure PCTCN2021082559-appb-000010
Figure PCTCN2021082559-appb-000011
表中“/”表示未添加。
二、扣电测试：
将负极活性材料、导电炭黑与聚合物按照质量比80：10：10加去离子水经过搅成浆料，利用刮刀涂成100um厚度的涂层，85℃经过12小时真空干燥箱烘干后，利用在干燥环境中用冲压机切成直径为1cm的圆片，在手套箱中以金属锂片作为对电极，隔离膜选择ceglard复合膜，加入电解液组装成扣式电池。运用蓝电(LAND)系列电池测试对电池进行充放电测试，测试其充放电性能。
三、锂离子电池的性能测试：
(1)极片粘结力测试方法：
将负极活性材料、导电炭黑与聚合物按照质量比80：10：10加去离子水经过搅成浆料，利用刮刀涂成50um厚度的涂层，85℃经过12小时真空干燥箱烘干后。裁剪成尺寸为2cm×10cm样条，将样条涂层面在宽为2cm的双面胶(3M VBH4920)上对齐贴合，用2kg压辊来回辊3～4次。样条通过万能材料试验机，180°单轴拉伸模式，夹具速度50mm/min，拉伸50mm后计算拉力平均值得到。
(2)0.1C充电克容量测试方法：
采用如上制作的扣电，通过蓝电测试系统测试。流程如下：静置2h，0.05C至0.05V,静置1h，100uA恒流至0.05V,静置10min,0.5C恒流至2V。计算克容量.
(3)50圈容量保持率测试方法：
采用如上制作的扣电，通过蓝电测试系统测试。流程如下：静置30min，0.05C至2V，静置10min，0.05C放电至0.005V，循环上述流程3次。静置10min，0.2C至2V静置10min，0.2C至0.005V，循环该步骤50次后，计算最后容量比初始容量比值。四、粘结剂性能测试：
(1)粘结剂玻璃化温度的测试方法：
粘结剂胶液在70℃下烘干24h，得到胶膜，取胶膜测试。测试方法参考国家标准GB/T 13464-2008。测试温度范围：-50～200℃，升温速率10℃/min。
(2)粘结剂粘度的测试方法：
配置的粘结剂胶液中固体含量为4％，取粘结剂胶液测试。测试方法参考国家标准GB/T 10247-2008中椎-板型旋转粘度计，恒定测试温度25℃，恒定剪切速率0.1 1/s。
将制备得到的实施例1至33(即表中的S1至S33)以及对比例1至3(即表中的D1至D3)进行性能测试，测试结果如表2所示。
表2
Figure PCTCN2021082559-appb-000012
Figure PCTCN2021082559-appb-000013
根据上表1及表2中的实施例1至6的测试数据可知，当粘结剂中的式III所示含氰基基团的结构单元摩尔占比、式II所示的含阴离子基团的结构单元的摩尔占比、式II中的阴离子基团保持不变时，随着式I所示的结构单元的摩尔占比的增大，即酚羟基基团比例增多，粘结剂的粘度先增大，后减小。
如图1a、图1b及图2所示，对比例1的粘结剂中不添加式I结构单元时，粘结剂的粘结力低，极片有脱膜风险，50周循环容量保持率低。实施例3的循环容量保持率高于对比例1。
根据实施例7至10、实施例3的测试数据可知，当粘结剂中的式I所示的结构单元摩尔占比、式II所示的含阴离子基团的结构单元的摩尔占比、式II中的阴离子基团保持不变时，随着式III所示的结构单元的摩尔占比的增大，即氰基比例增多，粘结剂的粘度增大；但是当式III所示的结构单元的摩尔占比大于55mol％时，粘结剂的粘度过大，无法水溶，降低其的使用便捷性。优选地，式III所示的结构单元在所述粘结剂中的摩尔占比为40mol％至55mol％，进一步优选地，式III所示的结构单元在所述粘结剂中的摩尔占比为50mol％至55mol％。
进一步结合对比例2的测试数据可知，当粘结剂中不添加式III的结构单元时，粘结剂的粘结力低，极片有脱膜风险，50周循环容量保持率低。根据实施例11至16、实施例3的测试数据可知，当粘结剂中的式I所示的结构单元的摩尔占比、式III所示的结构单元摩尔占比、式II中的阴离子基团保持不变时，随着式II所示的结构单元的摩尔占比的增大，即粘结剂中的盐化的阴离子基团增加，粘结剂在电池循环过程中能 提供更多锂离子，又能与锂离子周围溶剂竞争，帮助锂离子脱溶剂化，缓解锂离子嵌入受阻，提升电化学装置的动力学性能。优选地，式II所示的结构单元在所述粘结剂中的摩尔占比为15mol％至45mol％，进一步优选地，式II所示的结构单元在所述粘结剂中的摩尔占比为20mol％至30mol％。
进一步结合对比例3的测试数据可知，当粘结剂中不添加式II的结构单元时，电化学装置动力学差，高倍率下表现出来的克容量低。
根据实施例3、17至18的测试数据可知，粘结剂中的式II中的阴离子基团不同时，对粘结剂的粘度、电池容量保持率影响不大。
根据实施例3、19至21的测试数据可知，负极极片中的粘结剂含量增大，极片粘结力增加，电池容量保持率增加。
根据实施例3、22至24的测试数据可知，负极极片中的负极活性材料不同，但是对极片粘结力影响很小，可见该粘结剂适用于硅氧负极材料、硅碳负极材料、硅负极材料或石墨负极材料。
根据实施例3、25、26的测试数据可知，粘结剂中加入不同的式I所示的结构单元，分别为甲基丙烯酸改性邻苯二酚结构、丙烯酸改性邻苯二酚结构、甲基丙烯酸改性苯三酚结构，不同结构的式I所示结构单元对极片粘结力影响很小，相对于对比例1，均能够有效改善极片粘结力，提高电池容量保持率。
根据实施例3、27、28、29的测试数据可知，粘结剂中加入不同的式III所示的结构单元，分别为丙烯腈、甲基丙烯腈、5-己烯腈、烯丙基腈，不同结构的式III所示的结构单元对极片粘结力影响很小，相对于对比例2，均能够有效改善极片粘结力，提高电池容量保持率。
根据实施例3、实施例30至32的测试数据可知，粘结剂中加入不同的式II所示的结构单元，分别为丙烯酸锂、甲基丙烯酸锂、2-丙烯酰胺-2-甲基丙磺酸、对苯乙烯磺酸，不同结构的式II所示的结构单元对极片粘结力影响很小，相对于对比例3，均能够有效改善极片粘结力，提高电池容量保持率。
根据实施例3、实施例33的测试数据可知，粘结剂中加入不同的功能性单体，分别为NN亚甲基双丙烯酰胺、聚乙二醇双丙烯酸酯，不同的功能性单体对极片粘结力影响很小，能够有效改善极片粘结力，提高电池容量保持率。
本申请虽然以较佳实施例公开如上，但并不是用来限定权利要求，任何本领域技术人员在不脱离本申请构思的前提下，都可以做出若干可能的变动和修改，因此本申请的保护范围应当以本申请权利要求所界定的范围为准。

Claims (13)

  1. 一种粘结剂，其特征在于，所述粘结剂为含有如式I、式II及式III所示的结构单元的聚合物：
    Figure PCTCN2021082559-appb-100001
    其中，R 1独立地选自取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；
    R 2选自酚羟基，且所述酚羟基的数量为2至5；
    R 3选自C、S、N、P中的任意一种；X选自Li、Na、K中的任意一种；
    R 4、R 5各自独立地选自氢原子、取代或未取代的C1-C10烷基、取代或未取代的C2-C10烯基、取代或未取代的C2-C10炔基、取代或未取代的C6-C20芳基中的任意一种；
    n1、n2、n3各自独立的为大于零的整数。
  2. 根据权利要求1所述的粘结剂，其特征在于，所述式I所示的结构单元中的R 2
    Figure PCTCN2021082559-appb-100002
    其中，
    Figure PCTCN2021082559-appb-100003
    表示与相邻原子的结合位点。
  3. 根据权利要求1所述的粘结剂，其特征在于，
    式I所示的结构单元在所述粘结剂中的摩尔占比为5mol％至30mol％；
    式II所示的结构单元在所述粘结剂中的摩尔占比为10mol％至60mol％；
    式III所示的结构单元在所述粘结剂中的摩尔占比为35mol％至55mol％。
  4. 根据权利要求1所述的粘结剂，其特征在于，所述粘结剂还包括质量占比为0wt％至1wt％的功能性单体，所述功能性单体包括丙烯酰胺类衍生物单体、丙烯酸类 衍生物单体中的至少一种。
  5. 根据权利要求4所述的粘结剂，其特征在于，所述丙烯酰胺类衍生物单体包括丙烯酰胺，N-甲基丙烯酰胺、N-乙基丙烯酰胺、N-丁基丙烯酰胺或NN-亚甲基双丙烯酰中的至少一种。
  6. 根据权利要求4所述的粘结剂，其特征在于，所述丙烯酸类衍生物单体包括丙烯酸甲酯、丙烯酸乙酯、丙烯酸正丁酯、丙烯酸叔丁酯、丙烯酸2-乙基己酯、丙烯酸环己基酯、丙烯酸异冰片酯、丙烯酸羟乙酯、丙烯酸羟丙酯、乙酸乙烯酯、甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸正丁酯、甲基丙烯酸2-乙基己酯、甲基丙烯酸环己基酯、甲基丙烯酸异冰片酯、甲基丙烯酸-羟乙酯、甲基丙烯酸羟丙酯、甲基丙烯酸环氧丙酯或聚氧乙烯二丙烯酸酯中的至少一种。
  7. 根据权利要求1所述的粘结剂，其特征在于，所述粘结剂的pH值为3至12。
  8. 根据权利要求1至7任一项所述的粘结剂，其特征在于，所述粘结剂满足以下特征a至c中的至少一种：
    a.所述粘结剂的玻璃化转变温度为80℃至200℃；
    b.所述粘结剂的固体含量为4％时，所述粘结剂的粘度为1000mPa·s至20000mPa·s；
    c.所述粘结剂的分子量在1000至500万之间。
  9. 根据权利要求1所述的粘结剂，其特征在于，所述粘结剂还包括溶剂，所述溶剂为有机溶剂或水。
  10. 根据权利要求1所述的粘结剂，其特征在于，所述粘结剂还包括添加剂，所述添加剂包括分散剂、流平剂、润湿剂、消泡剂、增柔剂中的至少一种。
  11. 根据权利要求1所述的粘结剂，其特征在于，所述粘结剂应用于锂离子电池的负极和/或正极。
  12. 一种电化学装置，包括正极极片、负极极片、隔离膜和电解液，其特征在于，所述正极极片、所述负极极片、所述隔离膜中至少之一含有权利要求1至11任一项所述的粘结剂。
  13. 根据权利要求12所述的电化学装置，其特征在于，所述负极极片包括负极集流体和负极活性物质层，所述粘结剂占所述负极活性物质层的质量占比为3.0wt％至6.0wt％。
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