WO2013163862A1 - 电极活性材料组成物、电极和锂离子二次电池 - Google Patents

电极活性材料组成物、电极和锂离子二次电池 Download PDF

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WO2013163862A1
WO2013163862A1 PCT/CN2012/082581 CN2012082581W WO2013163862A1 WO 2013163862 A1 WO2013163862 A1 WO 2013163862A1 CN 2012082581 W CN2012082581 W CN 2012082581W WO 2013163862 A1 WO2013163862 A1 WO 2013163862A1
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active material
electrode active
electrode
lithium
compound
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PCT/CN2012/082581
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English (en)
French (fr)
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马紫峰
赵正威
苗振国
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上海中聚佳华电池科技有限公司
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Priority to US14/398,065 priority Critical patent/US20150140424A1/en
Publication of WO2013163862A1 publication Critical patent/WO2013163862A1/zh

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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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • 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 invention relates to an electrode active material composition of a lithium ion secondary battery, an aqueous slurry and an electrode for a lithium ion secondary battery, and a lithium ion secondary battery including the same.
  • lithium ion secondary batteries have gradually replaced traditional products such as lead acid, nickel cadmium and nickel hydrogen in recent years due to their high discharge voltage, high energy density and long cycle life.
  • the secondary battery is responsible for the main role of small secondary batteries for electronic equipment, and is expected to be applied to applications such as electric vehicles and energy storage power stations.
  • an electrode of a lithium ion secondary battery is generally obtained by dispersing and mixing an electrode active material and a binder in an organic solvent or water, and an auxiliary material such as a conductive agent, a thickener, and a dispersant added as needed.
  • a coatable electrode slurry was obtained, which was then coated on a current collector, dried and further compacted to obtain an electrode.
  • a positive electrode preparation technique for a lithium ion secondary battery typically using a water-insoluble polyvinylidene fluoride (PVdF) as a binder, using an organic solvent N-methylpyrrolidone (Li P) to dissolve PVdF and using Li P as a slurry
  • PVdF water-insoluble polyvinylidene fluoride
  • Li P organic solvent N-methylpyrrolidone
  • the dispersion medium was prepared, and the electrode slurry was prepared under anhydrous conditions. After the slurry was pulled, the solvent was evaporated to obtain a dried electrode.
  • the volatilization of the organic solvent not only pollutes the environment but also the health of the operator, and the solvent evaporated in the drying process must be recycled. This results in high cost of the organic solvent, energy consumption of the evaporated and recovered organic solvent, and environmental pollution problems.
  • the PVdF binder is unstable at high temperatures, easily decomposes under high temperature conditions, and undergoes an exothermic reaction with the positive active
  • lithium-ion secondary battery water-based adhesives such as Chengdu Yindile Power Technology Co., Ltd., invented a water-dispersible latex of acrylonitrile multi-copolymer (Chinese patent) CN101457131 )
  • the related product is sold, but the electrode using the binder is too hard and brittle, and the flexibility is insufficient to be processed and wound.
  • SBR styrene-butadiene rubber
  • the present patent JP 2002-260637 discloses a solution for achieving high current collection in a negative electrode, which comprises an active material layer comprising an active material composed of a silicon-containing material and a polyimide binder under a non-oxidizing atmosphere.
  • a negative electrode which comprises an active material layer comprising an active material composed of a silicon-containing material and a polyimide binder under a non-oxidizing atmosphere.
  • the high temperature curing treatment, the negative electrode thus obtained exhibited good charge and discharge cycle characteristics.
  • U.S. Patent No. 20060099506A1 uses an aliphatic polyimide as a binder for a silicon alloy negative electrode, which reduces the carbonyl content of the polymer and reduces the battery involved in the electrochemical reaction compared to the use of an aromatic polyimide binder. Irreversible capacity consumption.
  • Polyimide has good adhesion characteristics, excellent mechanical strength and chemical stability, and its problem as an electrode binder is not in the polyimide itself but in the process.
  • Most polyimides are insoluble or poorly soluble, usually in the organic solvent such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide or dimethyl sulfoxide solution to synthesize their precursor polyamide.
  • Acid (PAA) and organically dissolved in polyamic acid The solution is used in the form of a solution, and finally the polyamic acid is dehydrated and cyclized under high temperature to form a polyimide solid.
  • the polyamic acid solution has poor stability, is easily precipitated, precipitates, and is difficult to store. Therefore, the use of a polyimide binder has inconvenient use, high cost of an organic solvent, energy consumption of evaporation and recovery of an organic solvent, and environmental hazard of an organic solvent.
  • the main object of the present invention is to solve the high cost of the organic solvent caused by the positive electrode preparation process using the PVdF binder and the Li P solvent system, the energy consumption of the organic solvent to be evaporated and recovered, and the environmental pollution problem, and the high temperature instability of the PVdF binder. It is easy to decompose under high temperature conditions and has an exothermic reaction with the positive active material to improve battery life and safety.
  • the object of the present invention is to adapt to the development trend of high energy density of lithium ion secondary batteries and to develop a new type of alloy negative electrode such as Si, Sn and the like having a high specific capacity, and to provide a solution for the micronization of the alloy negative electrode from the current collector.
  • the present invention provides an electrode active material composition for a lithium ion secondary battery, the composition comprising: an electrode active material and a binder component polyamideimide compound.
  • the electrode active material is one of a positive electrode active material and a negative electrode active material.
  • the polyamideimide compound as an electrode binder is present in the electrode slurry in the form of its precursor polyamide-amic acid compound.
  • the electrode slurry contains the above electrode active material and a polyamide-amic acid compound, and water is used as a dispersion medium.
  • the polyamide-amic acid compound comprises 1 represents the repeating unit of the structure:
  • the two amide groups linked to the aromatic ring represented by Formula 1 represent the characteristic structures of the 1, 3 and 1, 4 polyamide-amic acid compounds.
  • ⁇ is an organic or inorganic basic compound which reacts with a carboxyl group to form a moiety.
  • the positive electrode active material is a powder material capable of lithiation and delithiation, and is selected from the group consisting of: lithium metal oxides containing cobalt, nickel, manganese, and vanadium; lithium metal containing iron, cobalt, nickel, manganese, and vanadium. Phosphate; lithium metal silicate comprising iron, cobalt, nickel, manganese, vanadium; lithium titanate; and combinations thereof.
  • the negative electrode active material is selected from a material capable of reversibly intercalating/deintercalating lithium ions, and a material capable of reacting with lithium to form a lithium-containing compound.
  • a material capable of reversibly intercalating/deintercalating lithium ions is a carbon-based material
  • a material capable of reacting with lithium to form a lithium-containing compound is selected from the group consisting of tin and tin in the electrode active material composition of the present invention, as an electrode paste
  • the polyamideimide compound of the binder comprises a repeating unit of the amide-imide structure represented by Formula 2 and an amide-amic acid structural repeating unit represented by Formula 3:
  • the two amide groups on the central aromatic ring shown in Formula 3 represent two characteristic structures of 1, 3 and 1, 4 polyamide-amic acid.
  • R is a divalent subaromatic group
  • the molar ratio of the amide-imide structural unit accounts for 80% or more of the total number of moles of the amide-imide structural unit and the amide-amic acid structural unit.
  • the polyamideimide compound as an electrode binder has a weight average molecular weight ranging from about 1,000 to about 100,000.
  • the content of the polyamide-imide compound is 0. 2-20% by weight, the electrode activity is based on the total weight of the electrode active material, the polyamide-imide compound. 8 ⁇ The content of the substance is 80-99. 8 wt%.
  • the present invention provides an electrode comprising a current collector and an electrode active material composition supported on a current collector, the electrode active material composition being characterized as described above.
  • the present invention also provides a lithium ion secondary battery comprising a positive electrode and a negative electrode and a nonaqueous electrolyte, wherein the positive electrode and/or the negative electrode are the electrodes described above.
  • the electrode binder contains a polyamideimide compound. Since a large amount of imide groups are present in the molecular structure of the polyamideimide, high adhesion can be exhibited. Since the imide group has high polarity, it has high adhesion to the electrode active material particles and the metal foil as the electrode current collector such as aluminum foil or copper foil. Further, a large amount of an amide group (-Li-co-) is present in the molecular structure of the polyamideimide to lower the rigidity of the molecular chain. Using polyamideimide as an electrode binder, excellent adhesion can be obtained, Mechanical strength and stability improve electrode flexibility compared to polyimide binders.
  • the polyamideimide binder is particularly suitable for a novel Si, Sn-based alloy anode having high expansion characteristics, which can suppress the conduction path failure between active material particles and the active material particles from the current collector during charge and discharge of the electrode.
  • the detachment improves the current collecting property in the electrode, improves the charge and discharge cycle characteristics of the electrode, and obtains an improved processability than an electrode using a polyimide binder.
  • the electrode binder polyamideimide is present in the aqueous electrode slurry in the form of its precursor polyamide-amic acid compound, which is completely dissolved or mostly dissolved in water.
  • Water-based batching and pulping is realized in the electrode manufacturing process, which avoids the use of high-boiling, toxic organic solvents such as Li P, which not only saves the cost of organic solvents but also avoids environmental pollution.
  • Li P toxic organic solvents
  • due to the high adhesion of polyamideimide and excellent chemical and electrochemical stability it can replace the existing PVdF binder with the positive electrode preparation process of Li P solvent system, and solve the high temperature instability of PVdF binder.
  • water-soluble binder precursor polyamide-amic acid compound and water-soluble binder products such as carboxymethyl cellulose CMC, polyvinylpyrrolidone PVP, and water-dispersed latex binder products such as styrene-butadiene rubber SBR, PTFE, acrylonitrile copolymers are used together as electrode binders to meet pulping process requirements and product performance requirements.
  • the polyamideimide compound as an electrode binder is present in the electrode slurry in the form of its precursor polyamide-amic acid compound containing the structure represented by Formula 1.
  • R is derived from an aromatic divalent subaromatic group, Wherein A is a divalent group, and by way of non-limiting example, may be selected from the group consisting of: S0 2 -, a CO-, -C(CH 3 )-O-, -S-, and a chemical bond.
  • the organic or inorganic basic compound is neutralized with a carboxyl group to form a moiety.
  • the organic or inorganic basic compound is preferably an amine compound, and a non-limiting example is a tertiary amine. More preferably, the low boiling point, volatile tertiary amine, and by way of limitation, triethylamine, is such that -CO-Ri is easily decomposed and volatilized during heating, and the polyamide-amic acid is cyclized and cured.
  • the polyamide-amic acid compound may be composed of repeating units of the formulae 1 and 3, and it is inevitable to form a repeating unit of the formula 2 in the polyamide-amic acid synthesis process.
  • the content of the repeating unit of the formula 1 is 60% or more based on the total number of moles of the repeating unit represented by Formula 1 and Formula 2 and Formula 3. Preferably, it is 80% or more.
  • the polyamide-amic acid compound may be added in the form of an aqueous solution of a polyamide-amic acid compound, or may be added as a solid of a polyamic acid and then subjected to an acid in the slurry.
  • the base is neutralized to dissolve and disperse.
  • aqueous solutions of polyamide-amic acid compounds can be selected Solvay
  • the positive electrode provided by the present invention comprises a positive electrode current collector and a positive electrode active material supported on the current collector.
  • the positive electrode active material composition comprises a positive electrode active material and a binder component polyamideimide compound.
  • the content of the polyamideimide compound is from 0.2 to 20% by weight, preferably from 1 to 12% by weight, more preferably from 3 to 8% by weight, based on the total weight of the positive electrode active material and the polyamideimide compound. .
  • the positive active material is a powder material capable of undergoing lithiation and delithiation, and is selected from the group consisting of: lithium metal oxides containing cobalt, nickel, manganese, and vanadium; lithium metal phosphates containing iron, cobalt, nickel, manganese, and vanadium; a lithium metal silicate of cobalt, nickel, manganese, vanadium; lithium titanate; and combinations thereof.
  • the positive active material may be LiCo0 2 , LiNi0 2 , LiMn0 2 , LiMn 2 0 4 , NCA, H3, Li 3 V 2 (P0 4 ) 3 , LiVP0 4 F, LiMnP0 4 or LiFeP0 4 /C One or several of them.
  • the positive electrode active material composition may further contain a conductive agent to improve electron conduction between the active material particles and between the active material particles and the current collector.
  • the conductive agent may be any conductive agent known in the art, and non-limiting examples include natural graphite, artificial graphite, black block black, ketjen black, carbon fiber, carbon nanotube, conductive carbon black, conductive polymer, and Metal powder or metal fiber of copper, nickel, aluminum, silver, etc.
  • the weight ratio of the conductive agent to the positive electrode active material may be (1 to 15): 100, preferably (2 to 10): 100, more preferably (3 to 8): 100.
  • the positive electrode active material composition may further contain other binder components, and the specific gravity in the positive electrode active material composition is preferably 8% or less, more preferably 5% or less.
  • Non-limiting examples include polyvinyl alcohol, carboxymethyl cellulose, hydroxy propylene cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, and acrylonitrile based polymers.
  • a high polymer containing an unsaturated olefin double bond, such as styrene-butadiene rubber, is susceptible to degradation in an electrochemical reaction at a positive electrode potential, and thus does not act as a positive electrode binder. I want to choose.
  • the cathode current collector is not particularly limited and may be a cathode current collector commonly used in lithium ion batteries, such as aluminum foil, nickel mesh, and nickel foam.
  • the preparation method of the positive electrode can be carried out according to the following method, and the positive electrode active material, the binder and the conductive agent are prepared into a slurry by using deionized water, and the amount of deionized water can be flexibly adjusted according to the viscosity requirement and the operability requirement of the slurry. Adjustments are well known to those skilled in the art. An appropriate amount of an organic solvent or alcohol which can be blended with water may be added during the batching process to promote dissolution and dispersion of the binder.
  • the obtained positive electrode slurry is coated on a positive electrode current collector and dried, and then heated to cure the polyamide amic acid compound at a curing temperature of 150 ° C to 450 ° C, preferably 200 ° C to 350 ° C, more preferably 250 ° C to 300 ° C.
  • the curing heating time is preferably 0.5 to 12 hours, and is adjusted according to the curing temperature so that the molar ratio of the amide-imide structural unit in the polyamideimide binder accounts for the amide-imide structural unit and the amide-
  • the total number of moles of the amic acid structural unit is 80% or more, preferably 90% or more, and more preferably 95% or more.
  • the negative electrode provided by the present invention comprises a negative electrode current collector and a negative electrode active material composition supported on the current collector.
  • the negative electrode active material composition contains a negative electrode active material and a binder component polyamideimide compound.
  • the content of the polyamideimide compound is from 0.2 to 20% by weight, preferably from 1 to 12% by weight, more preferably from 3 to 8% by weight, based on the total weight of the negative electrode active material and the polyamideimide compound. .
  • the negative electrode active material is selected from a material capable of reversibly intercalating/deintercalating lithium ions, and a material capable of reacting with lithium to form a lithium-containing compound.
  • materials capable of reversibly intercalating/deintercalating lithium ions are carbon-based materials such as natural graphite, artificial graphite, mesocarbon microbeads, and hard carbon.
  • a material capable of reacting with lithium to form a lithium-containing compound is selected from the group consisting of: tin, tin alloy, tin oxide, silicon, silicon alloy, silicon oxide, Silicon carbon composite. And their combination.
  • the negative electrode active material composition may further contain a conductive agent, which may be any conductive agent known in the art, and includes, without limitation, natural graphite, artificial graphite, black block, ketjen black, carbon fiber, nanometer. Carbon tube, conductive carbon black, conductive polymer, and metal powder or metal fiber containing copper, nickel, aluminum, silver, and the like.
  • the amount of the conductive agent to be added may be adjusted according to the conductivity of the negative electrode active material, and the specific gravity of the negative electrode active material may be 15% or less, preferably 10% or less, more preferably 8% or less.
  • the negative electrode active material composition may further contain other binder components, and the specific gravity in the negative electrode active material composition is preferably 8% or less, more preferably 5% or less.
  • Non-limiting examples include polyvinyl alcohol, carboxymethyl cellulose, hydroxy propylene cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, acrylonitrile based polymers, styrene butadiene rubber, and nitrile rubber.
  • the anode current collector is not particularly limited and may be a cathode current collector commonly used in lithium ion batteries, such as copper foil, nickel copper alloy foil, stainless steel foil, nickel mesh, and foamed nickel.
  • a nickel-copper alloy foil is preferably used.
  • the preparation method of the negative electrode is similar to the above preparation method of the positive electrode, and will not be described in detail herein.
  • the present invention provides a lithium ion secondary battery comprising a positive electrode and a negative electrode and a non-aqueous electrolyte, and the positive electrode and/or the negative electrode are electrodes provided by the present invention.
  • the positive electrode provided by the present invention when used, the negative electrode provided by the present invention can be used for the counter electrode, and a negative electrode known in the art can also be used.
  • the positive electrode provided by the present invention when used, the negative electrode provided by the present invention is used, the positive electrode provided by the present invention can be used for the counter electrode, and a positive electrode known in the art can also be used.
  • the nonaqueous electrolyte is not particularly limited, and may be a nonaqueous electrolytic solution or a solid electrolyte.
  • the nonaqueous electrolytic solution includes a nonaqueous organic solvent and a lithium salt.
  • the non-aqueous organic solvent acts as a medium for transporting ions participating in the electrochemical reaction of the battery.
  • the non-aqueous organic solvent may include carbonates, carboxylates, ethers, ketones, alcohols or aprotic solvents.
  • Non-limiting examples of suitable carbonate-based solvents include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, fluorocarbonic acid. Ester and the like.
  • suitable carboxylic acid ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, methyl propionate, ethyl propionate, butyrolactone, and the like.
  • Non-limiting examples of suitable ether solvents include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and the like.
  • suitable ketone solvents include cyclohexanone and the like.
  • suitable alcohol solvents include ethanol, isopropanol, and the like.
  • suitable aprotic solvents include nitriles (e.g., X-CN, wherein X is a C2 to C20 linear, branched or cyclic hydrocarbon group, aryl group), an amide (e.g., dimethylformamide). , Dioxolane (eg 1, 3-dioxolane), sulfolane and the like.
  • the non-aqueous organic solvent may include a single solvent or a mixture of solvents. When a mixture of solvents is used, the mixing ratio can be controlled according to desired battery performance characteristics.
  • the carbonate-based solvent may include a mixture of a cyclic and a chain carbonate. When the cyclic and chain carbonates are mixed in a volume ratio ranging from about 1: 1 to about 1: 9 and the mixture is used as an electrolyte, the performance of the electrolyte can be improved.
  • the nonaqueous electrolyte may further include additives such as carbon dioxide, vinylene carbonate, fluoroethylene carbonate, sultone, biphenyl, cyclohexylbenzene to improve battery performance or use safety.
  • additives such as carbon dioxide, vinylene carbonate, fluoroethylene carbonate, sultone, biphenyl, cyclohexylbenzene to improve battery performance or use safety.
  • the additive can be used in an appropriate amount.
  • the lithium salt is dissolved in a non-aqueous organic solvent to facilitate the transfer of lithium ions between the positive electrode and the negative electrode.
  • suitable lithium salts include LiPF 6 , LiBF 4 , L iCF 3 S0 3 , LiN (S0 2 C 2 F 5 ) 2 , LiN (CF 3 S0 2 ) 2 , LiN (CF 3 S0 2 ) ( C 4 F 9 S0 2 ), LiC (CF 3 S0 2 ) 3 , LiC (C 2 F 5 S0 2 ) 3 , LiC 10 4 , L iCl, Li l, LiB0B, LiDF0B, LiTFOP, and combinations thereof.
  • the lithium salt can be used at a concentration ranging from about 0.1 M to about 2 M.
  • a gel-like polymer electrolyte obtained by impregnating an electrolyte solution with a polymer electrolyte such as polyethylene oxide or polyacrylonitrile, and an inorganic solid electrolyte such as Li l or Li 3 N can be used.
  • a lithium ion secondary battery generally includes a separator interposed between a positive electrode and a negative electrode.
  • suitable separators include polyethylene, polypropylene, polyvinylidene fluoride, polyimide, and multilayer composite films formed therefrom.
  • the preparation method of the lithium ion secondary battery provided by the present invention is carried out in accordance with a method known to those skilled in the art.
  • the method comprises stacking or winding a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode in sequence to form a cell, placing the cell into a battery can, injecting an electrolyte, and then sealing.
  • the shape of the lithium ion secondary battery of the present invention is not particularly limited, and is not limited to, for example, a steel shell cylindrical shape, a steel shell or an aluminum shell square, a bag-shaped aluminum plastic film soft pack, or the like.
  • the electrode active material composition, the electrode, and the battery in the examples and the comparative examples were evaluated by the following evaluation methods.
  • the obtained lithium ion secondary battery electrode was cut into a rectangular shape of 100 ⁇ X width and 50 ⁇ as a test piece, and a 3 ⁇ , 5 ⁇ , and 8 ⁇ stainless steel needle gauge was used as a circular mandrel, and the test piece was horizontally wound around the center axis. After bending to 180°, the fracture of the electrode test piece was observed. When changing the diameter of the mandrel for measurement, The following evaluation was performed by finding the diameter of the center axis of the fracture. The smaller the diameter of the center axis where the electrode does not break, the better the flexibility of the electrode.
  • the electrode was cut into a rectangular shape of 100 ⁇ X width and 2 5 ⁇ as a test piece, and the electrode active material layer was fixed upward. After the transparent tape was attached to the surface of the active material layer of the test piece, the measurement was carried out at a speed of 50 ⁇ /min from one end of the test piece. Peel stress. The measurement was performed 5 times, and the average value was taken as the peel strength. The greater the peel strength, the better the adhesion state of the electrode active material layer to the current collector.
  • the C5 is charged at a constant current of 0. 5C, and then charged at a constant voltage of 3.8V, and the off current is 0. 05C; 0 ⁇ The constant current discharged to 0. 2C to 2. 0V.
  • the resulting discharge capacity is the normal temperature initial capacity of the battery.
  • the battery was charged under the above conditions and discharged at a constant current of 0.5 C for 100 times, and the ratio of the discharge capacity of the 100th cycle to the first cycle was expressed as a percentage of the cycle characteristics.
  • the battery was charged under the above conditions at a temperature of 55 ° C and discharged at a constant current of 0.5 C for 100 times, and the ratio of the discharge capacity of the 100th cycle to the first cycle was expressed as a percentage, as a high-temperature cycle characteristic.
  • Electrode binder precursor Aqueous solution of polyamic acid amide compound Torlon AI-30, solid content 35 wt%.
  • LiFePO 4 /C powder, B block black and the above binder precursor were prepared into a slurry by deionized water at a specific gravity of 100:6: 17.1, and applied to both sides of an aluminum foil current collector having a thickness of 20 ⁇ . After drying at 80 ° C, it was cured by heating at 250 ° C for 3 hours. Rolling the pole piece into a positive electrode Al of 485 ⁇ X 44 ⁇ size.
  • LiFeP0 4 /C powder, B block black and polyvinylidene fluoride PVDF were prepared into a slurry by NMP at a specific gravity of 100:6:6, and coated on both sides of an aluminum foil current collector having a thickness of 20 ⁇ m. After drying at 120 ° C, the slitted pole piece was rolled to prepare a positive electrode AC1 of 485 mm x 41 ⁇ 2 m.
  • Electrode binder Acrylonitrile copolymer aqueous binder LA133, having a solid content of 15% by weight.
  • LiFePO 4 /C powder, B block black and the above binder solution were prepared into a slurry by deionized water at a specific gravity of 100:6:40, and applied to both sides of an aluminum foil current collector having a thickness of 20 ⁇ m. After drying at 120 ° C, the pole piece was rolled and made into a positive electrode AC 2 of 485 ⁇ X 44 ⁇ size.
  • Electrode binder precursor Aqueous solution of polyamic acid amide compound Torlon AI-30, solid content 35 wt%.
  • the artificial graphite, the block black and the above binder precursor were prepared into a slurry by deionized water at a specific gravity of 100:3: 12.8, and applied to both sides of a copper foil current collector having a thickness of 12 ⁇ m. After drying at 80 ° C, it was cured by heating at 250 ° C for 3 hours. Rolling the pole piece into a negative electrode B1 of 480 ⁇ 4 5 ⁇ .
  • Example 3
  • Electrode binder precursor Aqueous solution of polyamic acid amide compound Torlon AI-30, solid content 35 wt%.
  • Electrode binder precursor Aqueous solution of polyamic acid amide compound Torlon AI-30, solid content 35 wt%.
  • Microsilica powder (2 ⁇ 5 ⁇ ), carbon fiber and the above binder precursor were prepared into a slurry with deionized water at a specific gravity of 100:8:22.8, and coated on a copper foil current collector having a thickness of 18 ⁇ . . After drying at 80 ° C, it was cured by heating at 250 ° C for 3 hours. The slitting pole piece is rolled to form a negative electrode B3 of 480 mm x 45 mm size.
  • Electrode Binder Precursor Polyimide precursor polyamic acid solution having a solid content of about 25% by weight.
  • the microsilica powder (2 ⁇ 5 ⁇ ), the carbon fiber and the above binder solution were prepared into a slurry with a specific gravity of 100:8:32, and coated on a double-sided copper foil current collector having a thickness of 18 ⁇ m. After drying at 120 ° C, it was heat-cured at 250 ° C for 3 hours. Rolling the pole piece into a negative electrode BC 2 of 480 ⁇ 4 5 ⁇ size. 1
  • Diaphragm Use a 20 ⁇ thick PE film.
  • Non-aqueous electrolyte The electrolyte lithium salt is lmol/L LiPF 6 and the solvent system is EC+DEC+FEC (weight ratio 6:1).

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Abstract

本发明提供了用于锂离子二次电池的电极活性材料组成物、用于锂离子二次电池的电极和使用该电极活性材料组成物的锂离子二次电池。该电极活性材料组成物包括电极活性物质和粘结剂。所述粘结剂的特征在于，以聚酰胺-酰胺酸化合物的形式存在于电极浆料中，经过高温固化形成具有优异稳定性的聚酰胺酰亚胺化合物。所述电极浆料为水系浆料，可避免在电极制浆过程使用有机溶剂，并且获得的电极具有优异的结构稳定性并改善电池性能。

Description

电极活性材料组成物、 电极和锂离子二次电池
技术领域
本发明涉及锂离子二次电池的电极活性材料组成物、用于锂离子二次电池的 水系浆料和电极、 以及包括该电极的锂离子二次电池。
背景技术
为了满足便携电子设备小型化、 轻量化发展需求， 锂离子二次电池以其放电 电压高、 能量密度高和循环寿命长等优势， 近年来逐渐取代了铅酸、 镍镉、 镍氢 等传统二次电池， 担负着电子设备用小型二次电池的主要角色， 而且期待其应用 于电动汽车、 储能电站等用途方面。
现有技术通常通过以下方式得到锂离子二次电池的电极：在有机溶剂或水中 分散并混合电极活性物质和粘结剂， 以及根据需要添加的导电剂、增稠剂和分散 剂等辅助材料而得到可涂布的电极浆料， 然后将该浆料涂布在集流体上， 干燥后 进一步压实处理得到电极。
锂离子二次电池的正极制备技术，典型的使用非水溶性的聚偏氟乙烯（PVdF) 作为粘结剂， 使用有机溶剂 N-甲基吡咯烷酮（丽 P)溶解 PVdF并使用丽 P作为浆 料分散介质， 在无水条件下制备电极浆料， 拉浆后蒸发溶剂以获得干燥的电极。 在该实施过程中， 有机溶剂的挥发既污染环境又危害操作人员健康， 干燥过程蒸 发的溶剂必需回收处理。 由此形成有机溶剂的高成本、 蒸发和回收有机溶剂的能 耗以及环境污染问题。 此外， PVdF粘结剂高温不稳定， 容易在高温条件下分解 以及和正极活性材料发生放热反应， 影响电池寿命和使用安全。
为了解决上述问题， 人们也研究开发了锂离子二次电池水系粘结剂， 如成都 茵地乐电源科技有限公司发明了一种丙烯腈多元共聚物的水分散胶乳（中国专利 CN101457131 )并巿售相关产品， 但使用该粘结剂的电极过于硬脆、 柔韧性不足 而难以加工、 卷绕。 此外， 丁苯橡胶（SBR)胶乳粘结剂得到巿场认可并广泛应用 于碳类负极， 但其抗电化学氧化能力不足而不适用于正极。
另一方面， 为寻求锂离子二次电池的更高能量密度， 高比容量的新型电极活 性材料开发成为行业的研究热点。 为替代有 372mAh/g理论比容量局限的石墨负 极材料， 釆用能够与锂进行合金化反应而具有高比容量的 S i、 Sn等元素作为下 一代负极活性物质的候选， 相关研究十分活跃。 然而， 在使用与锂形成合金化反 应的材料作为主要活性物质的负极中， 锂的吸纳、释放过程中活性物质的体积变 化较大， 因此存在会产生活性物质的微粉化、 从集流体脱离、 电极内的集电性降 低而使充放电循环特性变差的问题。
曰本专利 JP2002-260637公开了一种实现负极内的高集电性的解决方案，在 非氧化性气氛下将包含由含硅材料构成的活性物质和聚酰亚胺粘结剂的活性物 质层高温固化处理， 由此得到的负极展示出良好的充放电循环特性。 美国专利 US20060099506A1使用脂肪族聚酰亚胺作为硅合金负极的粘结剂， 相比使用芳香 族聚酰亚胺粘结剂， 降低了聚合物羰基含量，减少了聚合物参与电化学反应引起 的电池不可逆容量消耗。 以及中国专利 CN101098026A、 CN101192665A,
CN1901260A等， 通过改变聚酰亚胺的分子结构或与其他粘结剂共同使用， 以抑 制 S i和 Sn类电极膨胀、 改善电化学性能。
聚酰亚胺具有 好的粘附特性、优异的机械强度和化学稳定性， 其作为电极 粘结剂的问题并不在于聚酰亚胺本身， 而在于工艺过程。 大多数聚酰亚胺是不溶 或难溶物质， 通常是在有机溶剂如 N-甲基吡咯烷酮、 二甲基乙酰胺、 二甲基甲 酰胺或二甲基亚砜溶液中合成其前驱体聚酰胺酸 (PAA) , 并以聚酰胺酸的有机溶 剂溶液的形式来使用， 最后聚酰胺酸在高温条件下脱水环化形成聚酰亚胺固体。 聚酰胺酸溶液稳定性差， 易析出、 沉淀， 难以储存。 因此， 使用聚酰亚胺粘结剂 存在使用的不便利、 有机溶剂的高成本、 蒸发和回收有机溶剂的能耗和有机溶剂 对环境的危害问题。
发明内容
发明要解决的问题
本发明的主要目的在于， 解决使用 PVdF粘结剂和丽 P溶剂体系的正极制备 工艺造成的有机溶剂高成本、 蒸发和回收有机溶剂的能耗以及环境污染问题， 以 及 PVdF粘结剂高温不稳定、 容易在高温条件下分解以及和正极活性材料发生放 热反应的问题， 改善电池寿命和使用安全。
本发明的目的还在于，适应锂离子二次电池的高能量密度发展需求和釆用具 有高比容量的 S i、 Sn等新型合金负极的发展趋势， 提供能够解决合金负极微粉 化、从集流体脱离、电极内集电性降低等问题的方法， 改善电极充放电循环特性， 并解决使用聚酰亚胺作为合金负极粘结剂引起的使用不便利、 有机溶剂高成本、 蒸发和回收有机溶剂的能耗以及有机溶剂对环境的危害问题。
用于解决问题的方案
本发明提供了一种用于锂离子二次电池的电极活性材料组成物，该组成物包 括： 电极活性物质和粘结剂成分聚酰胺酰亚胺化合物。 其中， 所述电极活性物质 为正极活性物质与负极活性物质的两者之一。
在本发明中， 作为电极粘结剂的聚酰胺酰亚胺化合物以其前驱体聚酰胺-酰 胺酸化合物的形式存在于电极浆料当中。该电极浆料包含上述电极活性物质、 聚 酰胺-酰胺酸化合物， 以水为分散介质。 其中， 所述聚酰胺-酰胺酸化合物包含式 1表示结构的重复单元:
Figure imgf000005_0001
式 1所示的芳环上链接两个酰胺基团代表 1， 3和 1， 4聚酰胺-酰胺酸化合物 的特征结构。 其中， ^为有机或无机碱性化合物与羧基中和反应形成部分。
在本发明中， 正极活性物质为能够发生锂化及脱锂的粉末材料， 选自： 包含 钴、 镍、 锰、 钒的锂金属氧化物； 包含铁、 钴、 镍、 锰、 钒的锂金属磷酸盐； 包 含铁、 钴、 镍、 锰、 钒的锂金属硅酸盐； 钛酸锂； 以及它们的组合。
在本发明中， 负极活性物质在能够可逆地进行锂离子的嵌入 /脱嵌的材料、 能够与锂反应形成含锂化合物的材料中选择。其中， 能够可逆地进行锂离子的嵌 入 /脱嵌的材料是碳类材料， 能够与锂反应形成含锂化合物的材料选自： 锡、 锡 在本发明的电极活性材料组成物中，作为电极粘结剂的聚酰胺酰亚胺化合物 包含式 2表示的酰胺-酰亚胺结构的重复单元和式 3表示的酰胺-酰胺酸结构重复 单元：
式 2
Figure imgf000005_0002
Figure imgf000006_0001
式 3所示中芳环上链接两个酰胺基团代表 1， 3和 1， 4聚酰胺-酰胺酸的两种 特征结构。
其中， R为二价亚芳香基， 所述酰胺-酰亚胺结构单元的摩尔比例占所述酰 胺 -酰亚胺结构单元与所述酰胺-酰胺酸结构单元的摩尔总数的 80%以上。
在本发明中， 作为电极粘结剂的聚酰胺酰亚胺化合物具有从大约 1000到大 约 100000范围内的重均分子量。 在电极活性材料组成物中， 以所述电极活性物 质、 聚酰胺酰亚胺化合物的总重量为基准， 所述聚酰胺酰亚胺化合物的含量为 0. 2-20重量％, 所述电极活性物质的含量为 80-99. 8重量％。
本发明提供了一种电极，该电极包括集流体和负载在集流体上的电极活性材 料组成物， 该电极活性材料组成物的特征如上所述。
本发明还提供了一种锂离子二次电池， 其特征在于， 具备正极和负极和非水 电解质， 所述正极和 /或负极为上述的电极。
发明的效果
在本发明中， 电极粘结剂包含聚酰胺酰亚胺化合物。 由于聚酰胺酰亚胺分子 结构中存在大量的酰亚胺基团， 因此可以表现出高粘结性。 由于酰亚胺基团具有 高极性， 因此与电极活性物质颗粒、 作为电极集流体的金属箔例如铝箔、 铜箔的 粘结性高。 再者， 聚酰胺酰亚胺分子结构中还存在大量的酰胺基团（ -丽 -co- ) , 使分子链的刚性降低。 以聚酰胺酰亚胺作为电极粘结剂， 可获得优异的粘结性、 机械强度和稳定性， 与聚酰亚胺粘结剂相比， 改善了电极的柔韧性。 因此聚酰胺 酰亚胺粘结剂特别适用于具有高膨胀特性的新型 S i、 Sn类合金负极， 可以在电 极充放电过程中抑制活性物质颗粒之间的导电通道失效与活性物质颗粒从集流 体脱离， 改善电极内集电性， 改善电极充放电循环特性， 并获得比使用聚酰亚胺 粘结剂的电极改善的加工性能。
在本发明中， 电极粘结剂聚酰胺酰亚胺以其前驱体聚酰胺-酰胺酸化合物的 形式存在于水系电极浆料中， 该聚酰胺 -酰胺酸化合物完全溶解或大部分溶解于 水中。 在电极制作过程中实现了水系配料制浆， 避免了使用丽 P等高沸点、 有毒 有机溶剂， 既节约了有机溶剂成本又避免了环境污染。 另外， 由于聚酰胺酰亚胺 的高粘结性和优异的化学、 电化学稳定性， 可取代现有的 PVdF粘结剂配合丽 P 溶剂体系的正极制备工艺， 解决 PVdF粘结剂高温不稳定、 容易在高温条件下分 解以及和正极活性材料发生放热反应的问题，提高粘结剂的化学稳定性， 改善电 池寿命和使用安全。 更进一步， 水溶性的粘结剂前驱体聚酰胺-酰胺酸化合物可 以和水溶性粘结剂产品如羧甲基纤维素 CMC、 聚乙烯吡咯烷酮 PVP , 以及水分散 胶乳粘结剂产品如丁苯橡胶 SBR、 聚四氟乙烯 PTFE、 丙烯腈类共聚物， 共同作为 电极粘结剂， 以满足制浆涂布工艺需求和产品性能要求。
具体实施方式
以下， 对本发明进行进一步的详细说明。
在本发明中， 作为电极粘结剂的聚酰胺酰亚胺化合物以其前驱体聚酰胺-酰 胺酸化合物的形式存在于电极浆料当中， 所述聚酰胺-酰胺酸化合物包含式 1表 示结构的重复单元：
式 1
Figure imgf000008_0001
R是来源于芳香族二 二价亚芳香基， 可
Figure imgf000008_0002
Figure imgf000008_0003
其中 A是二价基团， 非限制性举例， 可以选自： 一 S02—， 一 CO—， -C(CH3) 一 0—， -S-, 以及 化学键。
为有机或无机碱性化合物与羧基中和反应形成部分。所述有机或无机碱性 化合物优选胺类化合物， 非限制性举例为叔胺。 更优选低沸点、 易挥发叔胺， 非 限制性举例为三乙胺， 使 -CO-Ri容易在加热过程中分解、 挥发， 聚酰胺-酰胺酸 环化固化。
所述聚酰胺-酰胺酸化合物可以由式 1和式 3的重复单元共同组成， 并不可 避免的在聚酰胺 -酰胺酸合成过程中生成式 2重复单元。为了使聚酰胺-酰胺酸化 合物能够在电极浆料中完全溶解或至少大部分溶解，以式 1和式 2和式 3表示的 重复单元摩尔总数为基准， 式 1重复单元的含量在 60%以上， 优选 80%以上， 更 在配料制浆过程中，聚酰胺-酰胺酸化合物可以以聚酰胺 -酰胺酸化合物水溶 液的形式加入，也可以以聚酰胺酸固体的形式加入然后在浆料中进行酸碱中和使 其溶解分散。 非限制性举例， 聚酰胺-酰胺酸化合物水溶液可以选择 Solvay
Advanced Polymers, L. L. C. ½ Tor Ion AI_30和 Tor Ion AI-50C 本发明提供的正极，包括正极集流体和负载在集流体上的正极活性材料组成 正极活性材料组成物包含正极活性物质和粘结剂成分聚酰胺酰亚胺化合物。 以所述正极活性物质、 聚酰胺酰亚胺化合物的总重量为基准， 聚酰胺酰亚胺化合 物的含量为 0. 2-20重量％, 优选 1-12重量％, 更优选 3-8重量％。
正极活性物质为能够发生锂化及脱锂的粉末材料， 选自： 包含钴、 镍、 锰、 钒的锂金属氧化物； 包含铁、 钴、 镍、 锰、 钒的锂金属磷酸盐； 包含铁、 钴、 镍、 锰、 钒的锂金属硅酸盐； 钛酸锂； 以及它们的组合。 非限制性举例， 正极活性物 质可以是 LiCo02、 LiNi02、 LiMn02、 L iMn204、 NCA、 匿、 Li3V2 (P04) 3、 LiVP04F、 LiMnP04或 LiFeP04/C中的一种或几种。
正极活性材料组成物还可以进一步包含导电剂，以改善活性物质颗粒之间以 及活性物质颗粒与集流体之间的电子传导。所述导电剂可以釆用本领域所公知的 任何导电剂， 非限制性举例包括天然石墨、人造石墨、 乙块黑、科琴黑、碳纤维、 纳米碳管、 导电碳黑、 导电高分子和包含铜、 镍、 铝、 银等的金属粉末或金属纤 维。 导电剂与正极活性物质的重量比可以是（1 ~ 15) : 100 , 优选（2 ~ 10) : 100 , 更 优选（3 ~ 8)： 100。
除上述聚酰胺酰亚胺化合物以外，正极活性材料组成物还可以包含其他粘结 剂成分， 在正极活性材料组成物中的比重优选 8%以下， 更优选 5%以下。 非限制 性举例包括聚乙烯醇、 羧甲基纤维素、 羟基丙烯纤维素、 聚乙烯吡咯烷酮、 聚四 氟乙烯、 聚乙烯、 聚丙烯和丙烯腈类聚合物。 含有不饱和烯烃双键的高聚物如丁 苯橡胶， 在正极电位下易参与电化学反应发生降解， 因而不作为正极粘结剂的理 想选择。
在本发明中， 正极集流体没有特别限定， 可以为锂离子电池中常用的正极集 流体， 例如铝箔、 镍网、 泡沫镍。
正极的制备方法可以按照以下方法进行，用去离子水将正极活性物质、粘结 剂和导电剂制备成浆料，去离子水的加入量可根据浆料的粘度需求和可操作性要 求进行灵活调整， 具体为本领域技术人员所公知。 配料制浆过程中也可加入适量 能够与水共混的有机溶剂或醇类， 促进粘结剂的溶解和分散。 然后将所得正极浆 料涂布于正极集流体上并进行干燥， 然后再加热使聚酰胺酰胺酸化合物固化， 固 化温度为 150°C至 450°C , 优选 200°C至 350°C , 更优选 250°C至 300°C。 固化加 热时间优选 0. 5 ~ 12小时， 并根据固化温度调整，使所述聚酰胺酰亚胺粘结剂中 酰胺-酰亚胺结构单元的摩尔比例占酰胺 -酰亚胺结构单元与酰胺-酰胺酸结构单 元的摩尔总数的 80%以上， 优选 90%以上， 更优选 95%以上。
负极活性材料组成物与负极
本发明提供的负极，包括负极集流体和负载在集流体上的负极活性材料组成 负极活性材料组成物包含负极活性物质和粘结剂成分聚酰胺酰亚胺化合物。 以所述负极活性物质、 聚酰胺酰亚胺化合物的总重量为基准， 聚酰胺酰亚胺化合 物的含量为 0. 2-20重量％, 优选 1-12重量％, 更优选 3-8重量％。
负极活性物质在能够可逆地进行锂离子的嵌入 /脱嵌的材料、 能够与锂反应 形成含锂化合物的材料中选择。 其中， 能够可逆地进行锂离子的嵌入 /脱嵌的材 料是碳类材料， 例如天然石墨、 人造石墨、 中间相碳微球、 硬碳。 能够与锂反应 形成含锂化合物的材料选自： 锡、 锡合金、 锡氧化物、 硅、 硅合金、 硅氧化物、 硅碳复合材料。 以及它们的组合。
负极活性材料组成物还可以进一步包含导电剂，所述导电剂可以釆用本领域 所公知的任何导电剂， 非限制性举例包括天然石墨、人造石墨、 乙块黑、科琴黑、 碳纤维、 纳米碳管、 导电碳黑、 导电高分子和包含铜、 镍、 铝、 银等的金属粉末 或金属纤维。 导电剂的加入量可根据负极活性物质的导电性能调整， 与负极活性 物质的比重可以是 15%以下， 优选 10%以下， 更优选 8%以下。
除上述聚酰胺酰亚胺化合物以外，负极活性材料组成物还可以包含其他粘结 剂成分， 在负极活性材料组成物中的比重优选 8%以下， 更优选 5%以下。 非限制 性举例包括聚乙烯醇、 羧甲基纤维素、 羟基丙烯纤维素、 聚乙烯吡咯烷酮、 聚四 氟乙烯、 聚乙烯、 聚丙烯、 丙烯腈类聚合物、 丁苯橡胶以及丁腈橡胶。
在本发明中， 负极集流体没有特别限定， 可以为锂离子电池中常用的负极集 流体， 例如铜箔、 镍铜合金箔、 不锈钢箔、 镍网、 泡沫镍。 针对硅锡类负极， 优 选使用镍铜合金箔。
负极的制备方法与上述正极制备方法类似， 这里不再详述。
锂离子二次电池
本发明提供了一种锂离子二次电池， 其特征在于， 具备正极和负极和非水电 解质， 所述正极和 /或负极为本发明提供的电极。 更进一步说明， 例如， 使用本 发明提供的正极时， 对电极可以使用本发明提供的负极， 也可以使用行业公知的 负极。 使用本发明提供的负极时， 对电极可以使用本发明提供的正极， 也可以使 用行业公知的正极。
在本发明的锂离子二次电池中， 非水电解质没有特别限定， 可以为非水电解 液或固态电解质。 所述非水电解液包括非水有机溶剂和锂盐。非水有机溶剂作为传输参与电池 的电化学反应的离子的介质。非水有机溶剂可以包括碳酸酯类、羧酸酯类、醚类、 酮类、醇类或者非质子溶剂。合适的碳酸酯类溶剂的非限制性举例包括碳酸二甲 酯、 碳酸二乙酯、 碳酸二丙酯、 碳酸甲丙酯、 碳酸甲乙酯、 碳酸亚乙酯、 碳酸亚 丙酯、 氟代碳酸酯等。 合适的羧酸酯类溶剂的非限制性举例包括乙酸甲酯、 乙酸 乙酯、 乙酸正丙酯、 丙酸甲酯、 丙酸乙酯、 丁内酯等。 合适的醚类溶剂的非限制 性举例包括二丁基醚、 四乙二醇二甲醚、 二乙二醇二甲醚、 二甲氧基乙烷、 2_ 甲基四氢呋喃、 四氢呋喃等。 合适的酮类溶剂的非限制性举例包括环己酮等。 合 适的醇类溶剂的非限制性举例包括乙醇、 异丙醇等。合适的非质子溶剂的非限制 性举例包括腈（例如 X-CN, 其中， X是 C2到 C20的直链、 支链或环状的烃基、 芳基） 、 酰胺（例如二甲基甲酰胺） 、 二氧戊环 （例如 1， 3-二氧戊环） 、 环丁 砜等。
非水有机溶剂可以包括单一溶剂或者溶剂的混合物。 当使用溶剂的混合物 时， 可以根据期望的电池性能特性来控制混合比率。碳酸酯类溶剂可以包括环状 和链状的碳酸酯的混合物。 当环状和链状的碳酸酯按照从大约 1: 1到大约 1: 9 的范围内的体积比混合并且将该混合物用作电解液时， 可以改进电解液的性能。
非水电解液还可以包括添加剂， 例如， 二氧化碳、 碳酸亚乙烯酯、 氟代碳酸 亚乙酯、 磺酸内酯、 联苯、 环己基苯， 以改进电池性能或使用安全。 可以以合适 的量来使用该添加剂。
将锂盐溶解在非水有机溶剂中， 便于在正极和负极之间传输锂离子。合适的 锂盐的非限制性举例包括 LiPF6、 LiBF4、 L iCF3S03、 LiN (S02C2F5) 2、 LiN (CF3S02) 2、 LiN (CF3S02) (C4F9S02)、 LiC (CF3S02) 3、 LiC (C2F5S02) 3、 LiC 104、 L iCl、 Li l、 LiB0B、 LiDF0B、 LiTFOP以及它们的组合。 可以在从大约 0. 1M到大约 2M范围内的浓度 使用锂盐。
合适的固态电解质可以使用将电解液浸渍到聚环氧乙烷、聚丙烯腈等聚合物 电解质而成的凝胶状聚合物电解质， 以及 Li l、 Li3N等无机固态电解质。
锂离子二次电池通常包括介于正极和负极之间的隔膜。合适的隔膜的非限制 性举例包含聚乙烯、 聚丙烯、 聚偏氟乙烯、 聚酰亚胺以及由它们形成的多层复合 膜。
本发明提供的锂离子二次电池的制备方法按照本领域的技术人员所公知的 方法进行。 一般来说， 该方法包括将正极、 负极和位于正极与负极之间的隔膜依 次叠放或卷绕形成电芯， 将电芯置入电池壳中， 注入电解液， 然后密封。 本发明 的锂离子二次电池对形状没有特别限定， 非限制性举例为钢壳圆柱形、钢壳或铝 壳方形、 袋状铝塑膜软包等。
实施例
以下， 通过列举具体实施例来进一步详细说明本发明，但本发明并不受实施 例的任何限定， 可以在不改变发明内容的范围内适当变更来实施。
用以下的评价方法对实施例和比较例中的电极活性材料组成物、电极以及电 池进行评价。
评价方法
【电极柔韧性】
将得到的锂离子二次电池用电极切成长 100匪 X宽 50匪的长方形作为试验 片， 使用 3匪、 5匪和 8匪不锈钢针规作为圆心轴， 将试验片绕着圆心轴从水平 状态弯曲到 180° 后，观察电极试验片的断裂情况。改变心轴的直径进行测定时， 通过发现断裂的圆心轴直径来进行如下评价。 电极不断裂的圆心轴直径越小， 表 示电极柔韧性越好。
圆心轴直径为 3匪， 未发现断裂： A
圆心轴直径为 5匪， 未发现断裂： B
圆心轴直径为 8匪， 未发现断裂： C
圆心轴直径为 8匪， 发现断裂： D
【剥离强度】
将电极切成长 100匪 X宽 25匪的长方形作为试验片， 将电极活性材料层面 向上进行固定。在试验片的活性材料层表面粘贴透明胶带后， 测定从试验片的一 端以 50匪 /min的速度做 180。 剥离应力。 测定 5次， 取其平均值作为剥离强度。 剥离强度越大， 表示电极活性物质层与集流体的粘结状态越好。
【电池性能】
在 25 °C的温度下， 将所得锂离子二次电池以 0. 5C的恒定电流充电至 3. 8V, 再以 3. 8V的恒定电压充电， 截止电流为 0. 05C; 搁置 l Omin; 然后以 0. 2C的恒 定电流放电至 2. 0V。 得到的放电容量为电池的常温初始容量。
随后按照上述充电方式进行充电后， 以 2C的恒定电流放电至 2. 0V。 以百分 率表示 2C放电容量相对于 0. 2C放电容量的比， 作为倍率放电特性。
将以上述条件充电和以 0. 5C的恒定电流放电循环 100次， 以百分率表示第 100次循环相对于第 1次循环的放电容量之比， 作为常温循环特性。
在 55 °C的环境下， 电池以上述条件充电和以 0. 5C的恒定电流放电循环 100 次， 以百分率表示第 100次循环相对于第 1次循环的放电容量之比， 作为高温循 环特性。 电极的制作
实施例 1
电极粘结剂前体： 聚酰胺酰胺酸化合物水溶液 Torlon AI-30, 固含量为 35wt%。
将 LiFeP04/C粉体、 乙块黑和上述粘结剂前体以 100: 6: 17.1的比重， 用去 离子水调制成浆料， 涂布于厚度为 20 μη 的铝箔集流体双面。 80°C烘干后， 在 250°C下 3小时加热固化。 滚压分切极片， 制成 485匪 X 44匪大小的正极 Al。
比较例 1
将 LiFeP04/C粉体、 乙块黑和聚偏二氟乙烯 PVDF以 100: 6: 6的比重， 用 NMP 调制成浆料， 涂布于厚度为 20 μηι的铝箔集流体双面。 120°C干燥后滚压分切极 片， 制成 485mmx 4½m大小的正极 AC1。
比较例 2
电极粘结剂： 丙烯腈共聚物水性粘结剂 LA133, 固含量为 15wt%。
将 LiFeP04/C粉体、 乙块黑和上述粘结剂溶液以 100: 6: 40的比重， 用去离 子水调制成浆料， 涂布于厚度为 20μη的铝箔集流体双面。 120°C烘干后， 滚压 分切极片， 制成 485匪 X 44匪大小的正极 AC2。
实施例 2
电极粘结剂前体： 聚酰胺酰胺酸化合物水溶液 Torlon AI-30, 固含量为 35wt%。
将人造石墨、 乙块黑和上述粘结剂前体以 100: 3: 12.8的比重， 用去离子水 调制成浆料， 涂布于厚度为 12 μηι的铜箔集流体双面。 80°C烘干后， 在 250°C下 3小时加热固化。 滚压分切极片， 制成 480匪 χ 45匪大小的负极 Bl。 实施例 3
电极粘结剂前体： 聚酰胺酰胺酸化合物水溶液 Torlon AI-30, 固含量为 35wt%。
将人造石墨、 乙块黑、 CMC和上述粘结剂前体以 100: 3: 2: 7.1的比重， 用去 离子水调制成浆料， 涂布于厚度为 12 μη 的铜箔集流体双面。 80°C烘干后， 在 250°C下 3小时加热固化。 滚压分切极片， 制成 480匪 χ 45匪大小的负极 B2。
比较例 3
将人造石墨、 乙块黑、 CMC和 SBR以 100: 3: 2: 2.5的比重， 用去离子水调制 成浆料， 涂布于厚度为 12 μη 的铜箔集流体双面。 120°C烘干后， 滚压分切极片， 制成 480mm X 45mm大小的负极 BC1。
实施例 4
电极粘结剂前体： 聚酰胺酰胺酸化合物水溶液 Torlon AI-30, 固含量为 35wt%。
将微硅粉（2μηι~5μηι)、 碳纤维和上述粘结剂前体以 100: 8: 22.8的比重， 用去离子水调制成浆料， 涂布于厚度为 18 μη的铜箔集流体双面。 80°C烘干后， 在 250°C下 3小时加热固化。 滚压分切极片， 制成 480mmx 45mm大小的负极 B3。
比较例 4
电极粘结剂前体： 聚酰亚胺的前驱体聚酰胺酸溶液， 固含量大约为 25wt%。 将微硅粉（2μηι~5μηι) 、 碳纤维和上述粘结剂溶液以 100: 8: 32的比重， 用丽 Ρ调制成浆料， 涂布于厚度为 18 μηι的铜箔集流体双面。 120°C烘干后， 在 250°C下 3小时加热固化。 滚压分切极片， 制成 480匪 χ 45匪大小的负极 BC2。 1
Figure imgf000017_0001
电池的制作
隔膜： 釆用 20 μ η厚的 PE膜。
非水电解液：电解质锂盐为 lmo l/L LiPF6, 溶剂体系为 EC+DEC+FEC (重量比6: 1 ) 。
2
常温初始 倍率放电 常温循环 高温循环 电池 正极 负极
容量 特性 特性 特性 本发明电
A1 B1 910mAh 95. 8% 93. 8% 89. 5% 池 1
本发明电
A1 B2 900mAh 93. 6% 92. 9% 86. 5% 池 2
本发明电
A1 BC1 920mAh 94. 0% 91. 7% 86. 8% 池 3
本发明电
A1 B3 11 30mAh 86. 7% 83. 3% 77. 6% 池 4
本发明电
AC1 B1 910mAh 96. 1% 92. 8% 83. 7% 池 5 本发明电
AC1 B2 920mAh 92. 7% 93. 1% 81. 9% 池 6
比较电池
AC1 BC1 930mAh 95. 6% 91. 8% 81. 6% 1
比较电池
AC1 BC2 1150mAh 83. 2% 78. 5% 71. 3% 2
比较电池
AC2 BC1 870mAh 88. 6% 89. 7% 82. 6% 3
比较电池
AC2 BC2 1020mAh 77. 5% 80. 6% 73. 5% 4

Claims

权利要求
1、 一种用于锂离子二次电池的电极活性材料组成物， 其包括电极活性物质 和聚酰胺酰亚胺化合物， 其特征在于，
所述聚酰胺酰亚胺化合物由聚酰胺-酰胺酸化合物经过高温固化得到， 所述 聚酰胺 -酰胺酸化合物包含下述式 1表示结构的重复单元， 具有可部分或完全在 水中溶解的特性，
式 1
Figure imgf000019_0001
式 1所示的芳环上链接两个酰胺基团代表 1， 3和 1， 4聚酰胺 -酰胺酸化合 的特征结构， 其中， 为有机或无机碱性化合物与羧基中和反应形成部分。
2、 根据权利要求 1所述的电极活性材料组成物， 其中， 所述电极活性物 为正极活性物质与负极活性物质的两者之一。
3、 根据权利要求 2所述的电极活性材料组成物， 其中， 所述正极活性物 为能够发生锂化及脱锂的粉末材料， 选自包含钴、 镍、 锰、 钒的锂金属氧化 4 包含铁、 钴、 镍、 锰、 钒的锂金属磷酸盐； 包含铁、 钴、 镍、 锰、 钒的锂金属 酸盐； 钛酸锂； 以及它们的组合。
4、 根据权利要求 2所述的电极活性材料组成物， 其中， 所述负极活性物 在能够可逆地进行锂离子的嵌入 /脱嵌的材料、 能够与锂反应形成含锂化合物 材料中选择。
5、 根据权利要求 4所述的电极活性材料组成物， 其中， 能够可逆地进行锂
6、 根据权利要求 4所述的电极活性材料组成物， 其中， 能够与锂反应形成 含锂化合物的材料选自锡、 锡合金、 锡氧化物、 硅、 硅合金、 硅氧化物、 硅碳复
7、 根据权利要求 1所述的电极活性材料组成物， 其中， 所述聚酰胺酰亚 j 化合物包含下述式 2表示的酰胺 -酰亚胺结构的重复单元和下述式 3表示的酰]! 酰胺酸结构重复单元：
式 2
Figure imgf000020_0001
式 3
Figure imgf000020_0002
式 3所示的芳环上链接两个酰胺基团代表 1， 3和 1， 4聚 '两; 特征士:
其中， R为二价亚芳香基， 所述酰胺-酰亚胺结构单元的摩
ί-酰亚胺结构单元与所述酰胺-酰胺酸结构单元的摩尔总数的 80%以上
8、 根据权利要求 1所述的电极活性材料组成物， 其中， 所述聚酰 ；亚 J 化合物具有从大约 1000到大约 100000范围内的重均分子量。
9、 根据权利要求 1所述的电极活性材料组成物， 其中， 以所述电极活性物 质、 聚酰胺酰亚胺化合物的总重量为基准， 所述聚酰胺酰亚胺化合物的含量为
0. 2-20重量％, 所述电极活性物质的含量为 80-99. 8重量％。 化合物以所述聚酰胺-酰胺酸化合物的形式存在于电极浆料当中， 所述电极浆料 包含所述聚酰胺-酰胺酸化合物、 权利要求 2-6任意一项所述活性物质， 以水为 分散介质。
11、 一种电极， 包括集流体和负载在集流体上的电极活性材料组成物， 其特 征在于， 所述电极活性材料组成物为权利要求 1-1 0中任一项所述的电极活性材 料组成物。
12、 一种锂离子二次电池， 其特征在于， 具备正极和负极和非水电解质， 所 述正极和 /或负极为权利要求 1 1所述的电极。
PCT/CN2012/082581 2012-05-03 2012-10-08 电极活性材料组成物、电极和锂离子二次电池 WO2013163862A1 (zh)

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