WO2017206181A1 - 电池的负极材料的制备方法、锂离子电池和固态电池 - Google Patents

电池的负极材料的制备方法、锂离子电池和固态电池 Download PDF

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WO2017206181A1
WO2017206181A1 PCT/CN2016/084786 CN2016084786W WO2017206181A1 WO 2017206181 A1 WO2017206181 A1 WO 2017206181A1 CN 2016084786 W CN2016084786 W CN 2016084786W WO 2017206181 A1 WO2017206181 A1 WO 2017206181A1
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negative electrode
hydroxide
battery
metal hydroxide
lithium
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PCT/CN2016/084786
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English (en)
French (fr)
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郝小罡
蒋蓉蓉
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罗伯特·博世有限公司
郝小罡
蒋蓉蓉
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Application filed by 罗伯特·博世有限公司, 郝小罡, 蒋蓉蓉 filed Critical 罗伯特·博世有限公司
Priority to CN201680086289.0A priority Critical patent/CN109196692A/zh
Priority to US16/306,601 priority patent/US11476454B2/en
Priority to DE112016006923.5T priority patent/DE112016006923T5/de
Priority to PCT/CN2016/084786 priority patent/WO2017206181A1/zh
Publication of WO2017206181A1 publication Critical patent/WO2017206181A1/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
    • H01M4/36—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a method of preparing a negative electrode material for a battery.
  • the present invention also relates to a lithium ion battery and a solid state battery, the negative electrode of which is prepared from the negative electrode material produced by the method.
  • a lithium ion battery generally includes a positive electrode (ie, a cathode) containing lithium, a negative electrode (ie, an anode), a separator, and an electrolyte.
  • the negative active materials commonly used in lithium ion batteries include graphite and silicon. Since silicon has a large theoretical capacity (Li 4.4 Si, 4200 mAh g -1 ), silicon is considered to be a promising negative active material for lithium ion batteries.
  • a negative electrode material containing a small particle active material for example, a nano- or micro-scale silicon-based material
  • a small particle active material for example, a nano- or micro-scale silicon-based material
  • the inventors of the present invention have developed a novel method of preparing a negative electrode material for a battery, as well as a novel lithium ion battery and a solid state battery.
  • the invention provides a method of preparing a negative electrode material for a battery, comprising the steps of:
  • step b) mixing the dry mixture obtained in step a) with an aqueous solvent to obtain the negative electrode material.
  • the alkali metal hydroxide and/or alkaline earth metal hydroxide is selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and combinations thereof, preferably lithium hydroxide.
  • the molar ratio of the carboxyl group in the polyacrylic acid to the total amount of hydroxide in the alkali metal hydroxide and/or alkaline earth metal hydroxide is from 0.2:1 to 1.5:1, preferably 0.8:1. To 1.2:1.
  • the alkali metal hydroxide and/or alkaline earth metal hydroxide comprises or is lithium hydroxide; and, in step a), the dry-mixed material further comprises lithium carbonate; preferably The molar ratio of lithium ions in lithium carbonate to carboxyl groups in polyacrylic acid is 0.0001:1 to 0.2:1.
  • the dry mixing time of step a) can be from 30 seconds to 30 minutes, preferably from 2 to 10 minutes, more preferably from 2 to 5 minutes.
  • the present invention provides another method of preparing a negative electrode material for a battery, comprising the steps of:
  • step c) mixing the dry mixture obtained in the step a), the aqueous solution of the alkali metal hydroxide obtained in the step b) and the aqueous solvent optionally present, thereby obtaining the negative electrode material.
  • the alkali metal hydroxide can be selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, and combinations thereof, preferably sodium hydroxide.
  • the molar ratio of carboxyl groups in the polyacrylic acid to hydroxide in the alkali metal hydroxide is from 0.2:1 to 1.5:1, preferably from 0.8:1 to 1.2:1.
  • the dry mixing time of step a) can be from 30 seconds to 30 minutes, preferably from 2 to 10 minutes, more preferably from 2 to 5 minutes.
  • the present invention also provides a lithium ion battery comprising a negative electrode prepared from a negative electrode material prepared according to the above method of the present invention.
  • the present invention also provides a solid state battery comprising a negative electrode prepared from a negative electrode material prepared according to the above method of the present invention.
  • the lithium ion battery or the negative electrode of the solid state battery further includes a negative electrode current collector, which may be a nickel foil or a copper foil coated with nickel.
  • the inventors of the present invention have unexpectedly found that the method for producing a negative electrode material of the present invention is simple in operation, short in time, and low in requirements for a mixing apparatus, and the preparation method of the present invention can be carried out by using a conventional mechanical stirring device. For industrial production, this represents considerable cost savings.
  • the negative electrode material produced by the method of the present invention has excellent performance, exhibiting uniform mixing of the negative electrode material slurry, long storage time, and good storage stability.
  • the negative electrode material obtained by the method of the present invention has strong adhesion, and can withstand the volume change of the negative electrode active material (especially the silicon-based material) during the repeated charge/discharge cycle, thereby providing excellent electric power.
  • Negative electrode and battery for chemical properties eg, cycle performance and rate performance).
  • FIG. 1 schematically illustrates a flow chart of a method of making a negative electrode material in accordance with some embodiments of the present invention.
  • FIG. 2 is a flow chart that schematically illustrates a method of making a negative electrode material in accordance with some embodiments of the present invention.
  • Fig. 3 schematically shows a flow chart of a method of preparing a negative electrode material according to the prior art.
  • FIG. 4 schematically shows a flow chart of a method of preparing a negative electrode material in accordance with an embodiment of the present invention.
  • FIG. 5 schematically shows a flow chart of a method of preparing a negative electrode material in accordance with an embodiment of the present invention.
  • Fig. 6 schematically shows a flow chart of a method of preparing a negative electrode material according to a comparative example.
  • Figure 7 compares the cycle performance of a lithium ion battery prepared according to comparative examples with some embodiments of the present invention.
  • Figure 8 compares the cycle performance of a lithium ion battery prepared in accordance with some embodiments of the present invention.
  • Ranges of values recited herein are intended to include the endpoints of the ranges, and all values and all sub-ranges within the range.
  • the term “comprising” or “including” as used herein means that other components or other steps that do not affect the final effect may also be included or included.
  • the methods and products of the present invention may comprise or include the essential technical features and/or defined features described herein, as well as any other and/or optional components, components, steps or defined features described herein.
  • the methods and products of the present invention may also be constructed from the essential technical features and/or defined features described herein, or consist essentially of the essential technical features and/or defined features described herein.
  • the present invention provides a method of preparing a negative electrode material for a battery, comprising the steps of:
  • the dry mixture obtained in the step a) is mixed with an aqueous solvent to obtain a negative electrode material.
  • alkali metal hydroxides and alkaline earth metal hydroxides there are no particular requirements for alkali metal hydroxides and alkaline earth metal hydroxides, and conventional alkali metal hydroxides and/or alkaline earth metal hydroxides can be used in the present invention.
  • the alkali metal hydroxide and/or alkaline earth metal hydroxide can be selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, and combinations thereof.
  • the alkali metal hydroxide and/or alkaline earth metal hydroxide is an alkali metal hydroxide, more preferably lithium hydroxide.
  • polyacrylic acid and an alkali metal hydroxide and/or an alkaline earth metal hydroxide can be chemically reacted in the presence of an aqueous solvent to form an alkali metal salt and/or an alkaline earth metal salt of polyacrylic acid.
  • the obtained alkali metal salt and/or alkaline earth metal salt of polyacrylic acid can be used as a binder of the negative electrode material.
  • the molar ratio of the carboxyl group in the polyacrylic acid to the total amount of hydroxide in the alkali metal hydroxide and/or alkaline earth metal hydroxide is from 0.2:1 to 1.5:1, preferably 0.8:1. To 1.2:1.
  • the dissolution rate of the alkali metal hydroxide and/or the alkaline earth metal hydroxide (for example, lithium hydroxide) in water is close to the dissolution rate of the polyacrylic acid in water, then the polyacrylic acid and the alkali metal hydroxide are included.
  • the dry mixture of the material and/or alkaline earth metal hydroxide is contacted with water, the dissolved alkali metal hydroxide and/or alkaline earth metal hydroxide and the dissolved polyacrylic acid can react very favorably to form polyacrylic acid.
  • the alkali metal salt and/or alkaline earth metal salt is advantageous for obtaining a negative electrode material which is uniformly mixed and completely reacted.
  • step a) of process one of the invention no inorganic solvents (including water) and organic solvents are added.
  • the crystal water contained in the material itself does not belong to the additionally added water.
  • Dry blending can be carried out by any suitable method, in any suitable order. In some instances, all materials to be dry blended can be added simultaneously. In some instances, various materials to be dry blended may also be added in sequence as needed. In some instances, it is also possible to previously mix two or more of the materials to be dry blended and then mix the resulting mixture with the remaining one or more materials.
  • the material of the negative electrode material can be prepared by mixing the material in any suitable manner, in any suitable order.
  • the dry mixture can be added to the aqueous solvent. In some instances, it is also possible to dissolve the water The agent is added to the dry mixture.
  • the mixing can be carried out continuously or batchwise. Stirring can be carried out throughout the first method as needed. Stirring may also be carried out during part of the method one, for example during the entire or part of the step a), and/or during the entire or part of the step b).
  • the stirring speeds can be set to be the same or different at different stages of mixing. You can set the appropriate mixing time as needed. For example, the mixing time can be set according to factors such as the stirring device, the stirring speed, and the mass of the agitated material. In some instances, the agitation speed is faster and the mixing time can be shorter. In some instances, the agitation speed is slower and the mixing time can be slower.
  • the present invention also provides a method of preparing a negative electrode material for a lithium ion battery, comprising the steps of:
  • the dry mixture obtained in the step a), the aqueous solution of the alkali metal hydroxide obtained in the step b), and an aqueous solvent optionally present are mixed to obtain a negative electrode material.
  • alkali metal hydroxides there are no particular requirements for alkali metal hydroxides, and conventional alkali metal hydroxides can be used in the present invention.
  • the alkali metal hydroxide can be selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, and combinations thereof, preferably sodium hydroxide.
  • polyacrylic acid and an alkali metal hydroxide can be chemically reacted in the presence of an aqueous solvent to form an alkali metal salt of polyacrylic acid.
  • An alkali metal salt of an acid can be used as a binder of the negative electrode material.
  • the molar ratio of carboxyl groups in the polyacrylic acid to hydroxide in the alkali metal hydroxide is from 0.2:1 to 1.5:1, preferably from 0.8:1 to 1.2:1.
  • the dissolution rate of the alkali metal hydroxide for example, sodium hydroxide
  • the dry mixture containing the polyacrylic acid is brought into contact with the aqueous solution of the alkali metal hydroxide.
  • the pre-dissolved alkali metal hydroxide and the polyacrylic acid which has just dissolved can be chemically reacted very favorably to form an alkali metal salt of polyacrylic acid.
  • the agglomeration of the material is not caused by the rapid deliquescence of the alkali metal hydroxide, which is advantageous for obtaining a slurry of the negative electrode material which is uniformly mixed and completely reacted.
  • steps a) and b) may be separately performed as needed, or a) and then b) may be performed first, or b) may be performed first and then a).
  • step a) of the second method of the invention no inorganic solvent (including water) and an organic solvent are added.
  • the crystal water contained in the material itself does not belong to the additionally added water.
  • Dry blending can be carried out by any suitable method, in any suitable order. In some instances, all materials to be dry blended can be added simultaneously. In some instances, various materials to be dry blended may also be added in sequence as needed. In some instances, it is also possible to premix two of the materials to be dry blended and then mix the resulting mixture with the rest of the material.
  • the aqueous solution of the alkali metal hydroxide can be prepared by any suitable method, in any suitable order. If desired, in some examples, an alkali metal hydroxide can be added to the water. In some instances, water can also be added to the alkali metal hydroxide.
  • the dry mixture, the aqueous solution of the alkali metal hydroxide and optionally the aqueous solvent may be mixed in any suitable manner, in any suitable order, to prepare a slurry of the negative electrode material.
  • a dry mixture, an aqueous solution of an alkali metal hydroxide, and an aqueous solvent optionally present may be added simultaneously.
  • various materials to be mixed may also be added in sequence as needed. In some instances, it is also possible to mix two of these materials in advance and then mix the resulting mixture with the remaining one.
  • step a), step b) and step c) of the second method of the invention the mixing can be connected Continue or intermittently. Stirring can be carried out throughout the second process, as needed. Stirring may also be carried out during part of the process two, for example during the entire process or part of the process of step a), and/or during the entire process or part of the process of step b), and/or throughout the process of step c) Stir in part or part of the process.
  • the stirring speeds can be set to be the same or different at different stages of mixing. You can set the appropriate mixing time as needed. For example, the mixing time can be set according to factors such as the stirring device, the stirring speed, and the mass of the agitated material. In some instances, the agitation speed is faster and the mixing time can be shorter. In some instances, the agitation speed is slower and the mixing time can be slower.
  • the prior art mentioned in the background includes the following two steps: preparation of a binder solution, that is, first mixing a binder (for example, PAA) with a solvent to prepare a binder solution; and then performing slurry preparation, That is, other materials for the negative electrode are added to the binder solution, thereby obtaining a slurry of the anode material.
  • a binder for example, PAA
  • slurry preparation That is, other materials for the negative electrode are added to the binder solution, thereby obtaining a slurry of the anode material.
  • wet the method of the prior art is hereinafter referred to as "wet" mixing.
  • wet There are many problems with wet mixing, for example, the viscosity of the binder solution is large, making it difficult to mix the binder solution with other materials. The mixing time is longer and the entire preparation process takes 5-20 hours.
  • step a) of the process of the invention the dry materials are mixed without the addition of any solvent, including water, and therefore, in the following, step a) is referred to as "dry" mixing.
  • the dry mixing can uniformly mix the materials in a short time (for example, 30 seconds to 30 minutes) and shorten the total time of the entire preparation process to, for example, no more than 2 hours, or even no more than 1.5 hours or no more than 1 hour.
  • the dry mixing method has low requirements on the mixing equipment, and the ordinary mechanical stirring device can meet the requirements, thereby greatly reducing the equipment cost and the energy consumption cost of the industrial production.
  • the negative electrode material slurry obtained by the method of the present invention has excellent properties such as uniform slurry, long storage time, and good storage stability. After a long period of storage, the viscosity of the slurry remained unchanged and the sedimentation of the solid components was not significant.
  • the negative electrode material slurry obtained by the method of the present invention has strong adhesion and is repeated During the charge/discharge cycle, the volume change of the negative electrode active material (especially the silicon-based material) can be withstood, so that the negative electrode and the battery having excellent electrochemical properties (for example, cycle performance and rate performance) can be provided.
  • the dry mixing time of step a) may be from 30 seconds to 30 minutes, preferably from 2 to 10 minutes, more preferably from 2 to 5 minutes.
  • the preparation time of the aqueous alkali metal hydroxide solution (step b) of the second method) may be from 1 to 30 minutes.
  • the slurry preparation time (step b of method one) or step c)) of method two may be no more than 2 hours, preferably no more than 1.5 hours, more preferably no more than 1 hour.
  • PAA polyacrylic acid
  • alkali metal hydroxide alkali metal hydroxide
  • alkaline earth metal hydroxide silicon-based material and carbon material used in the present invention.
  • the sum of the dry weights of all the materials in the anode material is 100% by weight.
  • one or more, preferably all, of polyacrylic acid (PAA), alkali metal hydroxide, alkaline earth metal hydroxide, silicon-based material, and carbon material are in the form of granules and/or Powdered, or ground into granules and/or powder.
  • PAA polyacrylic acid
  • alkali metal hydroxide alkali metal hydroxide
  • alkaline earth metal hydroxide silicon-based material
  • carbon material are in the form of granules and/or Powdered, or ground into granules and/or powder.
  • Silicon-based material refers to a material containing silicon. Silicon-based materials or silicon-containing materials known for use in lithium ion batteries or solid state batteries can be used in the present invention. Silicon-based materials are mainly used as active materials for battery negative electrodes.
  • active material refers to a material capable of intercalating/deintercalating lithium during repeated charge/discharge cycles.
  • the silicon-based material can be selected from the group consisting of silicon, silicon alloys, silicon oxides, silicon/carbon composites, and combinations thereof.
  • the silicon alloy may comprise silicon and one or more metals selected from the group consisting of titanium, tin, aluminum, lanthanum, cerium, arsenic, antimony, and lead.
  • the silicon oxide can be a mixture of various oxides of silicon, for example, the silicon oxide can be represented by SiO x with an average value of x of from about 0.5 to about 2.
  • the particle diameter of the silicon-based material is not particularly limited, and the particle diameter of a common silicon-based material is applicable to the present invention.
  • the particle size of the silicon-based material may be on the order of nanometers (ie, from 1 nanometer to less than 1 micrometer) or micrometer (ie, from greater than or equal to 1 micrometer to less than 1). Mm).
  • the silicon-based material may have a particle diameter of 30 nm to 15 ⁇ m, for example, 100 nm to 3 ⁇ m.
  • the silicon-based material may be included in an amount of 5 to 88% by weight, preferably 10 to 50% by weight, based on the total dry weight of the anode material.
  • the content of the silicon-based material is greater than or equal to 5% by weight, which can improve the capacity of the battery; the content of the silicon-based material is less than or equal to 88% by weight, which can improve the cycle performance of the battery.
  • Carbon material refers to a material containing carbon.
  • the carbon material is mainly used to improve the conductivity and dispersibility of the battery negative electrode, and/or as a filler.
  • the carbon material can be selected from the group consisting of carbon black, graphite, graphene, acetylene black, ketjen black, carbon nanotubes, carbon nanofibers, and combinations thereof.
  • the carbon black is preferably a superconducting carbon black (for example, Super P available from Timcal Co., Ltd., having a particle diameter of, for example, 20 nm).
  • the graphite is preferably a graphite powder (for example, having a particle diameter of about 1 to 30 ⁇ m) and/or flake graphite (for example, KS6L available from Timcal Co., for example, having a particle diameter of about 6 ⁇ m). These carbon materials may be used singly or in any combination. In some examples, two or three of superconducting carbon black, graphite powder, and flake graphite (for example, KS6L) may be used at the same time.
  • the superconducting carbon black has a small particle size and good electrical conductivity, which contributes to improving the one-dimensional conductivity and one-dimensional dispersibility of the negative electrode material.
  • Graphite powder and flake graphite have large particle diameters and good electrical conductivity, which contribute to improvement of two-dimensional conductivity, two-dimensional dispersibility and cycle performance of the negative electrode material, and can also be used as a filler.
  • the total content of carbon material may range from 0 to 80% by weight, preferably from 10 to 80% by weight, more preferably from 10 to 70% by weight, based on the total dry weight of the negative electrode material.
  • the total content of the carbon material is in these ranges, and the conductivity, dispersibility, and cycle performance of the anode material can be advantageously improved.
  • the aqueous solvent can be water or a mixture of water and water miscible solvent.
  • the aqueous solvent is water.
  • the aqueous solvent is a mixture of water and a water miscible solvent.
  • the water-miscible solvent may be an alcohol such as a C 1 -C 6 linear alcohol, preferably ethanol, n-propanol, isopropanol or a combination thereof.
  • the ratio of the weight of the aqueous solvent to the total dry weight of the negative electrode material is from 0.6:1 to 2:1. Such a ratio facilitates uniform mixing of the particulate material or dry powder material to form a stable slurry or suspension.
  • Polyacrylic acid and alkali metal hydroxide and/or alkaline earth metal hydroxide as described above The chemical reaction may take place in the presence of an aqueous solvent to form an alkali metal salt and/or an alkaline earth metal salt of polyacrylic acid.
  • the obtained alkali metal salt and/or alkaline earth metal salt of polyacrylic acid can be used as a binder of the negative electrode material.
  • the polyacrylic acid (PAA) may be used in an amount of 5 to 15% by weight, preferably 8 to 10% by weight, based on the total dry weight of the negative electrode material.
  • the molar ratio of the carboxyl group in the polyacrylic acid to the total amount of hydroxide in the alkali metal hydroxide and/or alkaline earth metal hydroxide is from 0.2:1 to 1.5:1, preferably 0.8:1. To 1.2:1.
  • the alkali metal hydroxide and/or alkaline earth metal hydroxide comprises or is lithium hydroxide, and, in step a), the dry mixed material further comprises lithium carbonate.
  • the molar ratio of lithium ions in the lithium carbonate to carboxyl groups in the polyacrylic acid is from 0.0001:1 to 0.2:1.
  • the negative electrode material slurry obtained by the method 1 of the present invention contains a composite of lithium polyacrylate and lithium carbonate, here, lithium polyacrylate and lithium carbonate.
  • the composite is used as a binder for the negative electrode material.
  • the silicon-based material is coated with lithium carbonate in the finally formed negative electrode material.
  • the method of the present invention specifically provides a solid-electrolyte interface.
  • first, decomposition and passivation of the solvent in the electrolyte can be reduced or avoided, so that the initial reversible capacity brought about by it can be reduced, the initial coulombic efficiency of the battery can be increased, and gas generation in the charge/discharge cycle can be avoided.
  • the present invention can be formed on the surface of a silicon-based material by actively adding lithium carbonate as compared with the uneven, loose and insulating solid-electrolyte interface which is strongly avoided in the prior art. It is uniform and compact lithium carbonate, and the formation of the solid-electrolyte interface can be suppressed, thereby reducing internal resistance and enhancing ionic conductivity.
  • the lithium carbonate solid-electrolyte interface is insoluble in the solvent (for example, carbonate) of the electrolyte, so that the uniformity of the lithium carbonate solid-electrolyte interface and the stability and purity of the electrolyte can be maintained for a long time.
  • the lithium carbonate solid-electrolyte interface can also separate the silicon-based material from the electrolyte to prevent undesired reactions between the silicon-based material and the electrolyte.
  • lithium carbonate as a lithium source can also reduce the consumption of lithium ions in the electrolyte in a continuous charge/discharge cycle.
  • the present invention adds lithium carbonate to the anode material instead of being added to the electrolyte. If lithium carbonate is added to the electrolytic solution, it is necessary to prepare lithium carbonate into an aqueous solution in advance, and then add an aqueous lithium carbonate solution to the electrolytic solution, and finally, it is necessary to remove water from the electrolytic solution, which is complicated and costly.
  • the present invention directly adds solid lithium carbonate to the negative electrode material, thereby avoiding the above disadvantages.
  • the present invention also provides a lithium ion battery comprising a negative electrode prepared from a negative electrode material prepared according to the aforementioned method of the present invention.
  • the present invention also provides a solid state battery comprising a negative electrode prepared from a negative electrode material prepared according to the aforementioned method of the present invention.
  • the lithium ion battery may further include a positive electrode, a separator, and an electrolyte.
  • the solid state battery may further comprise a positive electrode and an electrolyte, and optionally a separator.
  • a positive electrode can use a lithium based positive electrode.
  • a metal lithium such as a lithium-indium alloy
  • a laminate of lithium with one or more other metals such as a lithium-indium laminate
  • the electrolyte can be obtained by dissolving a lithium salt in an organic solvent.
  • a lithium salt there is no particular limitation on the lithium salt, and those lithium salts known to be usable for lithium ion batteries can be used in the present invention.
  • a suitable organic solvent can be a carbonate.
  • Carbonates useful in the present invention include, but are not limited to, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate, Fluoroethylene carbonate (FEC) and difluoroethylene carbonate; linear carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate and their fluorine And any combination of the above.
  • the separator can be made of polyolefins such as polyethylene, polypropylene, and polybutylene; polyesters such as polyethylene terephthalate.
  • the membrane can be in the form of a porous membrane or a porous sheet.
  • the separator may be a single layer or a laminate of two or more layers.
  • the electrolyte is solid. Electrolytes commonly used in solid-state batteries can be used in the present invention as long as these electrolytes are materials capable of conducting lithium ions.
  • the solid electrolyte may be polyethylene oxide (PEO), a sulfide that can conduct lithium ions, a chloride that can conduct lithium ions, or a combination of these.
  • the solid electrolyte may be a single layer or a laminate of two or more layers.
  • additives may optionally be included in the lithium ion battery or the solid battery of the present invention as long as these additives do not adversely affect the electrochemical performance of the battery.
  • the other additives, if present, may be included in or between the positive electrode, the negative electrode, the electrolyte, the solid electrolyte, and/or the separator.
  • the current collector is not particularly limited, and a current collector for a lithium ion battery or a solid battery can be used in the present invention.
  • the cathode current collector can be an aluminum foil.
  • the negative current collector can be a nickel foil or a copper foil coated with nickel. The inventors of the present invention have surprisingly found that by using a nickel foil or a copper foil coated with nickel as a negative electrode current collector, the adhesion between the negative electrode material and the negative electrode current collector is strong, thereby being in a continuous charge/discharge cycle. It can maintain the integrity of the negative electrode and the entire battery, improve the electrochemical performance of the battery, especially the cycle performance and rate performance.
  • the lithium ion battery and the solid state battery of the present invention can be used in an energy storage system or an electric vehicle.
  • Nano-silicon Anode active material, particle size 50 nm, purchased from Sigma-Aldrich.
  • Superconducting carbon black (Super P): a carbon material having a particle size of about 20 nm, available from Timcal Corporation.
  • KS6L flake graphite, carbon material, particle size of about 6 ⁇ m, purchased from Timcal Corporation.
  • Graphite powder carbon material, particle size 2-10 ⁇ m, purchased from Shenzhen Kejing Zhida Technology Co., Ltd.
  • PAA Polyacrylic acid, used to form a binder, volume average molecular weight (Mv): about 450,000, available from Aldrich.
  • Celgard 2325 Separator, polypropylene-polyethylene film (PP/PE), purchased from Shenzhen Kejing Zhida Technology Co., Ltd.
  • 2 g of Super P was weighed and added to a platinum-rich powder mixer (BBL800 mixer, purchased from Guangzhou Boyu Trading Co., Ltd.) at room temperature and normal pressure, with the permission of the mixer. Stir at a maximum speed (about 1000 rpm) for about 1 minute. Then, 18 g of nano-silicon, 20 g of KS6L, 50 g of graphite powder, 7 g of PAA and 3 g of LiOH ⁇ H 2 O were sequentially added to the platinum-rich powder mixer, and the mixture was stirred at the highest speed allowed by the mixer at each feeding interval. One minute, 100 g of dry mixture was obtained.
  • BBL800 mixer purchased from Guangzhou Boyu Trading Co., Ltd.
  • the dry mixture was sampled and placed between two 2 mm x 6 mm clear glass plates to visually inspect the sample for white spots or particles. If the sample has white spots or granules, the dry mixture in the mixer is continuously stirred for 1 minute at the highest speed allowed by the mixer. If there are no white spots in the sample and the sample is a homogeneous powder, proceed directly to the slurry preparation step below.
  • the dry mixture was sampled and placed between two 2 mm x 6 mm clear glass plates to visually inspect the sample for white spots or particles. If there are white spots or granules in the sample, the dry mixture in the mixer is continuously stirred for 1 minute at the highest speed allowed by the mixer. If there are no white spots in the sample and the sample is a homogeneous powder, proceed directly to the slurry preparation step below.
  • a negative electrode material slurry was prepared in the same manner as in Example 1, except that after adding 3 g of LiOH.H 2 O, 0.5 g of Li 2 CO 3 was further added, thereby obtaining 100.5 g of a dry mixture.
  • a vacuum mixer (CA-40 vacuum mixer, purchased from Guangzhou Haomei Equipment Co., Ltd.) at room temperature and normal pressure. While stirring at 1000 rpm, 7 g of PAA was added to water, and stirring was continued at 1000 rpm for 10 hours to obtain an aqueous solution of PAA. 3 g of LiOH was added to the aqueous solution of PAA, and the mixture was further stirred at a speed of 1000 rpm for 2 hours to obtain an aqueous solution of LiPAA. Then, stirring was continued at 1000 rpm for about 30 minutes.
  • CA-40 vacuum mixer purchased from Guangzhou Haomei Equipment Co., Ltd.
  • the negative electrode material slurry obtained in Examples 1-3 and Comparative Example 1 was separately coated on a copper foil, and then the coated copper foil was placed in a vacuum oven (Bentley VDL blast drying oven, Germany) at about 60 Dry at ° C for about 8 hours under vacuum.
  • the dried copper foil was punched into a plurality of negative pole pieces of ⁇ 12 mm using an EQ-T-06 battery pole piece punching machine (purchased from Shenzhen Weizhida Optoelectronics Technology Co., Ltd.).
  • the negative electrode tab thus obtained was used for the subsequent lithium ion battery preparation experiment, the pole piece uniformity test, and the pole piece adhesion test.
  • a button cell (CR2016) was assembled using various negative electrode tabs prepared as described above.
  • a lithium metal foil was used as the counter electrode.
  • 1M LiPF 6 in FEC/EC/DMC mixture of fluoroethylene carbonate (FEC), ethylene carbonate (EC) and dimethyl carbonate (DMC) in a volume ratio of 1:5:5)
  • FEC fluoroethylene carbonate
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • the solution was used as an electrolyte.
  • Celgard 2325 was used as the separator.
  • the lithium ion battery thus obtained was used for the electrochemical performance test according to Fig. 7 later.
  • a lithium ion battery was prepared in the same manner except that lithium nickel cobalt manganese oxide was used instead of lithium metal foil.
  • the lithium ion battery thus obtained was used for the electrochemical performance test according to Fig. 8 later.
  • Example 1 The negative electrode slurry obtained in Example 1 and Comparative Example 1 was sampled.
  • the viscosity of the sample was measured at a shear rate of 70 s -1 in a rheometer Anton Paar Rheometer MCR 52 (available from the representative office of Anton Paar, Shanghai, Germany).
  • the viscosity of the samples were measured after 1 day, 2 days, 5 days, and 7 days, and the results were recorded in Table 1 below.
  • the negative electrode material slurry prepared according to the method of the present invention has a long storage time and good storage stability.
  • the uniformity test was performed on the pole pieces prepared from the negative electrode material slurry of Example 1 and Comparative Example 1. 24 pole pieces were taken for each test, and the weight and thickness of the 24 pole pieces were measured, and the weight deviation and thickness deviation of the pole pieces were calculated according to the following sample standard deviation formula. The calculation results are recorded in Table 2 below.
  • S represents a weight deviation or a thickness deviation
  • N 24;
  • X i that is, X 1 , X 2 , ... up to X 24 , representing the weight or thickness of each of the 24 pole pieces;
  • the adhesion of the pole pieces obtained from the negative electrode material slurry of Example 1 and Comparative Example 1 was measured using a FMT-310 dynamometer (available from ALLURIS). Three pole pieces were taken for each test, and the adhesion measured by the three pole pieces was averaged, and the average value was recorded as the adhesion of the pole piece. Specifically, a 2 cm-wide transparent tape was adhered to one side of each of the pole pieces coated with the slurry, and the pole pieces to which the transparent tape was adhered were fixed to the upper and lower fixed ends of the dynamometer. The tape is pulled at a constant speed of 100 mm/min perpendicular to the surface of the pole piece, and the pulling force is slowly increased. The tensile force when the tape starts to be pulled is the measured adhesion of the pole piece (unit: N/m).
  • Fig. 7 compares the charge/discharge performance of a battery prepared by using the negative electrode slurry of Comparative Example 1, Example 1 and Example 3 at a current density of 1 C, wherein each battery employs a lithium metal foil as a counter electrode.
  • each battery was tested at 25 ° C in an Arbin battery test system (available from Arbin Corporation). In the voltage range of 0.01-0.9 V (vs Li/Li + ), each battery was subjected to a first charge/discharge cycle at 0.1 C, a second and a third charge/discharge cycle at 0.3 C, and 1C performs the remaining charge/discharge cycles.
  • the total loading in each negative electrode was about 7 mg/cm 2 .
  • Example 7 the battery obtained from the dry-mixed negative electrode material slurry of Example 1 had better cycle performance than the battery obtained by the wet-mixed negative electrode material slurry of Comparative Example 1.
  • Example 3 additionally added Li 2 CO 3 , which further improved the cycle performance of the battery.
  • Example 8 compares the charge/discharge performance of a battery prepared using the anode material slurry of Example 1, Example 2, and Example 3 at a current density of 1 C, wherein each battery uses lithium nickel cobalt manganese oxide as a counter electrode.
  • each battery was tested at 25 ° C in an Arbin battery test system (available from Arbin Corporation). In the voltage range of 2.5-4.2 V (positive lithium nickel cobalt manganate), each battery was subjected to a first charge/discharge cycle at 0.1 C, and a second and a third charge/discharge cycle was performed at 0.3 C, and All remaining charge/discharge cycles were performed at 1 C except for the 51st, 101st, 151st and 201st charge/discharge cycles at 0.1C. The total loading in each negative electrode was about 7 mg/cm 2 .
  • Example 1 Example 2 and Example 3 was obtained by dry mixing to obtain a slurry of a negative electrode material.
  • Example 2 NaPAA was used as the negative electrode binder, and the battery thus obtained had a better cycle performance than the battery obtained by using LiPAA as the negative electrode binder in Example 1.
  • Example 3 additionally added Li 2 CO 3 , which further improved the cycle performance of the battery.

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Abstract

本发明提供了一种制备电池的负极材料的方法，其包括以下步骤：a）在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：聚丙烯酸，硅基材料，和碱金属氢氧化物和/或碱土金属氢氧化物，和任选存在的碳材料；以及b）将步骤a）得到的干混合物与含水溶剂混合，从而得到所述负极材料。本发明还提供了锂离子电池和固态电池，所述锂离子电池和固态电池的负极由所述方法制得的负极材料制备。

Description

电池的负极材料的制备方法、锂离子电池和固态电池 技术领域
本发明涉及电池的负极材料的制备方法。本发明还涉及锂离子电池和固态电池，所述锂离子电池和固态电池的负极由所述方法制得的负极材料制备。
背景技术
锂离子电池的产生可以追溯到二十世纪八十年代晚期，在此之后，特别是在进入二十世纪九十年代之后，对锂离子电池的研究得到迅猛发展。
锂离子电池通常包含：含有锂的正极(即阴极)、负极(即阳极)、隔膜和电解液。
常用于锂离子电池的负极活性材料包括石墨和硅。由于硅具有较大的理论容量(Li4.4Si,4200mAh g-1)，因此，硅被认为是一种很有前景的用于锂离子电池的负极活性材料。
如图3所示，有人提出通过以下方法来制备包含石墨的负极材料：首先，将粘合剂与溶剂混合，从而制备粘合剂溶液；然后，将石墨和添加剂依次加入到所述粘合剂溶液中，由此得到负极材料浆料。
但是，当通过上述方法来制备包含小颗粒活性材料(例如，纳米级或微米级的硅基材料)的负极材料时，存在很多问题，例如，耗时长并且得到的浆料不均匀。
因此，需要开发能够克服上述缺点的制备电池负极材料的方法。
发明内容
经过深入的研究，本发明的发明人已经开发了新型的制备电池的负极材料的方法以及新型的锂离子电池和固态电池。
一方面，本发明提供一种制备电池的负极材料的方法，其包括以下步骤：
a)在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：
聚丙烯酸，
硅基材料，和
碱金属氢氧化物和/或碱土金属氢氧化物，和
任选存在的碳材料；以及
b)将步骤a)得到的干混合物与含水溶剂混合，从而得到所述负极材料。
在一些实例中，所述碱金属氢氧化物和/或碱土金属氢氧化物选自氢氧化锂、氢氧化钠、氢氧化钾、氢氧化钙和它们的组合，优选氢氧化锂。
在一些实例中，聚丙烯酸中的羧基与所述碱金属氢氧化物和/或碱土金属氢氧化物中的氢氧根的总量的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
在一些实例中，所述碱金属氢氧化物和/或碱土金属氢氧化物包含氢氧化锂或者为氢氧化锂；并且，在步骤a)中，被干混的物质还包含碳酸锂；优选地，碳酸锂中的锂离子与聚丙烯酸中的羧基的摩尔比为0.0001:1至0.2:1。
在一些实例中，步骤a)的干混时间可以为为30秒至30分钟，优选2-10分钟，更优选2-5分钟。
另一方面，本发明还提供了另一种制备电池的负极材料的方法，其包括以下步骤：
a)在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：
聚丙烯酸，
硅基材料，和
任选存在的碳材料；
b)将碱金属氢氧化物与水混合，从而得到碱金属氢氧化物的水溶液；以及
c)将步骤a)得到的干混合物、步骤b)得到的碱金属氢氧化物的水溶液和任选存在的含水溶剂混合，从而得到所述负极材料。
在一些实例中，所述碱金属氢氧化物可选自氢氧化锂、氢氧化钠、氢氧化钾和它们的组合，优选氢氧化钠。
在一些实例中，聚丙烯酸中的羧基与所述碱金属氢氧化物中的氢氧根的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
在一些实例中，步骤a)的干混时间可以为为30秒至30分钟，优选2-10分钟，更优选2-5分钟。
另一方面，本发明还提供了一种锂离子电池，其包含负极，所述负极由根据本发明的上述方法制得的负极材料制备。
在一方面，本发明还提供了一种固态电池，其包含负极，所述负极由根据本发明的上述方法制得的负极材料制备。
在一些实例中，所述锂离子电池或固态电池的负极还包含负极集流体，所述负极集流体可以是镍箔或涂布有镍的铜箔。
本发明的发明人出人意料地发现，本发明的制备负极材料的方法操作简单，耗时短，并且对混合设备的要求不高，可以采用普通的机械搅拌装置进行本发明的制备方法。对于工业生产来说，这代表着可观的成本节约。
而且，通过本发明的方法制得的负极材料具有优异的性能，表现在负极材料浆料混合均匀，储存时间长，并且储存稳定性好。
此外，通过本发明的方法制得的负极材料粘合力强，在重复的充电/放电循环过程中，可以经受住负极活性材料(特别是硅基材料)的体积变化，从而提供具有优异的电化学性能(例如，循环性能和倍率性能)的负极和电池。
参考以下附图，本发明的各种其它特征、方面和优点会变得更加 显而易见。
附图说明
图1示意性地示出了根据本发明的一些实施例制备负极材料的方法的流程图。
图2示意性地示出了根据本发明的一些实施例制备负极材料的方法的流程图。
图3示意性地示出了根据现有技术的制备负极材料的方法的流程图。
图4示意性地示出了根据本发明的实施例制备负极材料的方法的流程图。
图5示意性地示出了根据本发明的实施例制备负极材料的方法的流程图。
图6示意性地示出了根据对比例制备负极材料的方法的流程图。
图7比较了根据对比例与本发明的一些实施例制备的锂离子电池的循环性能。
图8比较了根据本发明的一些实施例制备的锂离子电池的循环性能。
具体实施方式
除非另外定义，本文使用的所有技术和科学术语均为与本发明所属领域技术人员通常理解的含义。若存在不一致的地方，则以本申请提供的定义为准。
除非另外指出，本文所列出的数值范围旨在包括范围的端点，和该范围之内的所有数值和所有子范围。
本文的材料、含量、方法、设备、实例和附图均是示例性的，除非特别说明，不应理解为限制性的。
本文所用的术语“电池(cell)”和“电池(battery)”可以互换。
本文所用的术语“包含”或“包括”指的是，也可以包含或包括不影响最终效果的其他组分或其他步骤。术语“包含”或“包括”覆 盖了“由……构成”和“主要由……构成”的情形。本发明的方法和产品可以包含或包括本文中描述的必要技术特征和/或限定特征，以及本文中描述的任何其他和/或任选存在的成分、组分、步骤或限定特征。本发明的方法和产品也可以由本文中描述的必要技术特征和/或限定特征构成，或者主要由本文中描述的必要技术特征和/或限定特征构成。
除非另外指出，在本文中，特别是在权利要求书中使用“一”、“一种”、“一个”、“所述”或类似的术语时，其后所限定的术语应理解为既可以是单数的，也可以是复数的。
术语“任选存在的”或“任选”表明两种可替代的备选方案，也就是说，在本文所述的方法和产品中，术语“任选存在的”或“任选”所限定的主题可以存在，也可以不存在。
除非另外指出，本文所用的所有材料和试剂均是市售可得的。
除非另外指出或者明显矛盾，本文进行的操作都可以在室温和常压下进行。
以下将详细描述本发明的实例。
[负极材料的制备方法]
[方法一]
一方面，如图1所示，本发明提供了一种制备电池的负极材料的方法，其包括以下步骤：
a)干法混合
在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：
聚丙烯酸，
硅基材料，和
碱金属氢氧化物和/或碱土金属氢氧化物，和
任选存在的碳材料；以及
b)浆料制备
将步骤a)得到的干混合物与含水溶剂混合，从而得到负极材料。
对碱金属氢氧化物和碱土金属氢氧化物没有特别的要求，常用的碱金属氢氧化物和/或碱土金属氢氧化物都可用于本发明。在一些实例中，所述碱金属氢氧化物和/或碱土金属氢氧化物可选自氢氧化锂、氢氧化钠、氢氧化钾、氢氧化钙和它们的组合。优选地，所述碱金属氢氧化物和/或碱土金属氢氧化物为碱金属氢氧化物，更优选氢氧化锂。
根据本发明的方法一，聚丙烯酸与碱金属氢氧化物和/或碱土金属氢氧化物可以在含水溶剂的存在下发生化学反应，生成聚丙烯酸的碱金属盐和/或碱土金属盐。得到的聚丙烯酸的碱金属盐和/或碱土金属盐可以用作负极材料的粘合剂。在一些实例中，聚丙烯酸中的羧基与所述碱金属氢氧化物和/或碱土金属氢氧化物中的氢氧根的总量的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
特别地，如果碱金属氢氧化物和/或碱土金属氢氧化物(例如氢氧化锂)在水中的溶解速率与聚丙烯酸在水中的溶解速率接近，那么，在使包含聚丙烯酸与碱金属氢氧化物和/或碱土金属氢氧化物的干混合物与水接触时，溶解了的碱金属氢氧化物和/或碱土金属氢氧化物与溶解了的聚丙烯酸可以非常有利地发生化学反应，生成聚丙烯酸的碱金属盐和/或碱土金属盐，有利于获得混合均匀和反应完全的负极材料。
在本发明方法一的步骤a)中，不添加任何无机溶剂(包括水)和有机溶剂。物料本身带有的结晶水不属于另外添加的水。可以通过任何合适的方法、以任何合适的次序进行干混。在一些实例中，可以同时添加所有待干混的物料。在一些实例中，根据需要，也可以依次添加待干混的各种物料。在一些实例中，也可以预先将待干混的材料中的两种或多种混合，再将得到的混合物与其余的一种或多种材料混合。
类似地，在本发明方法一的步骤b)中，可以任何合适的方法、以任何合适的次序混合物料，从而制备负极材料浆料。在一些实例中，可以将干混合物添加到含水溶剂中。在一些实例中，也可以将含水溶 剂添加到干混合物中。
在本发明方法一的步骤a)和步骤b)中，混合可以连续或间歇进行。根据需要，可以在方法一的整个过程中进行搅拌。也可以在方法一的部分过程中进行搅拌，例如在步骤a)的整个过程或部分过程中，和/或在步骤b)的整个过程或部分过程中进行搅拌。在混合的不同阶段，搅拌速度可以设置得相同或不同。可以根据需要任意设置合适的混合时间。例如，可以根据搅拌装置、搅拌速度和搅拌物料的质量等因素来设置混合时间。在一些实例中，搅拌速度较快，混合时间可以较短。在一些实例中，搅拌速度较慢，混合时间可以较慢。
[方法二]
另一方面，如图2所示，本发明还提供了一种制备锂离子电池的负极材料的方法，其包括以下步骤：
a)干法混合
在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：
聚丙烯酸，
硅基材料，和
任选存在的碳材料；
b)碱金属氢氧化物水溶液的制备
将碱金属氢氧化物与水混合，从而得到碱金属氢氧化物的水溶液；以及
c)浆料制备
将步骤a)得到的干混合物、步骤b)得到的碱金属氢氧化物的水溶液和任选存在的含水溶剂混合，从而得到负极材料。
对碱金属氢氧化物没有特别的要求，常用的碱金属氢氧化物都可用于本发明。在一些实例中，所述碱金属氢氧化物可选自氢氧化锂、氢氧化钠、氢氧化钾和它们的组合，优选氢氧化钠。
根据本发明的方法二，聚丙烯酸与碱金属氢氧化物可以在含水溶剂的存在下发生化学反应，生成聚丙烯酸的碱金属盐。得到的聚丙烯 酸的碱金属盐可以用作负极材料的粘合剂。在一些实例中，聚丙烯酸中的羧基与所述碱金属氢氧化物中的氢氧根的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
特别地，如果碱金属氢氧化物(例如氢氧化钠)在水中的溶解速率远快于聚丙烯酸在水中的溶解速率，那么，在使包含聚丙烯酸的干混合物与碱金属氢氧化物的水溶液接触时，预先溶解了的碱金属氢氧化物与刚刚发生溶解的聚丙烯酸可以非常有利地发生化学反应，生成聚丙烯酸的碱金属盐。并且，不会因碱金属氢氧化物的快速潮解而引起物料团聚，有利于获得混合均匀和反应完全的负极材料浆料。
在本发明方法二中，根据需要，可以同时分别进行步骤a)和b)，也可以先进行a)然后进行b)，还可以先进行b)然后进行a)。
在本发明方法二的步骤a)中，不添加任何无机溶剂(包括水)和有机溶剂。物料本身带有的结晶水不属于另外添加的水。可以通过任何合适的方法、以任何合适的次序进行干混。在一些实例中，可以同时添加所有待干混的物料。在一些实例中，根据需要，也可以依次添加待干混的各种物料。在一些实例中，也可以预先将待干混的材料中的两种混合，再将得到的混合物与其余的材料混合。
类似地，在本发明方法二的步骤b)中，可以任何合适的方法、以任何合适的次序混合物料，从而制备碱金属氢氧化物的水溶液。根据需要，在一些实例中，可以将碱金属氢氧化物添加到水中。在一些实例中，也可以将水添加到碱金属氢氧化物中。
类似地，在本发明方法二的步骤c)中，可以任何合适的方法、以任何合适的次序混合干混合物、碱金属氢氧化物的水溶液和任选存在的含水溶剂，从而制备负极材料浆料。在一些实例中，可以同时添加干混合物、碱金属氢氧化物的水溶液和任选存在的含水溶剂。在一些实例中，根据需要，也可以依次添加待混合的各种物料。在一些实例中，也可以预先将这些材料中的两种混合，再将得到的混合物与其余的一种材料混合。
在本发明方法二的步骤a)、步骤b)和步骤c)中，混合可以连 续或间歇进行。根据需要，可以在方法二的整个过程中进行搅拌。也可以在方法二的部分过程中进行搅拌，例如在步骤a)的整个过程或部分过程中、和/或在步骤b)的整个过程或部分过程中、和/或在步骤c)的整个过程或部分过程中进行搅拌。在混合的不同阶段，搅拌速度可以设置得相同或不同。可以根据需要任意设置合适的混合时间。例如，可以根据搅拌装置、搅拌速度和搅拌物料的质量等因素来设置混合时间。在一些实例中，搅拌速度较快，混合时间可以较短。在一些实例中，搅拌速度较慢，混合时间可以较慢。
背景技术中提到的现有技术包括以下两个步骤：粘合剂溶液的制备，即，首先将粘合剂(例如PAA)与溶剂混合，从而制备粘合剂溶液；然后进行浆料制备，即，将用于负极的其他材料加入到所述粘合剂溶液中，由此得到负极材料浆料。由于现有技术在第一步就已经采用了溶剂，因此，在下文中，将现有技术的该方法称为“湿法”混合。湿法混合存在很多问题，例如，粘合剂溶液的粘度较大，导致粘合剂溶液难以与其他材料混合均匀。混合时间较长，整个制备工艺耗时为5-20小时。
除非另有说明或者存在矛盾，下文中提及本发明的方法时，均适用于本发明的前述两种方法，即，方法一和方法二。
在本发明方法的步骤a)中，均在不添加任何溶剂(包括水)的情况下，将干物料混合，因此，在下文中，将步骤a)均称为“干法”混合。干法混合可以在短时间内(例如，30秒至30分钟)将物料混合均匀，并且将整个制备工艺的总时间缩短至例如不超过2小时，甚至不超过1.5小时或不超过1小时。此外，干法混合对混合设备的要求不高，普通的机械搅拌装置就可以满足要求，因此可以大大降低工业生产的设备成本和能耗成本。
而且，通过本发明的方法制得的负极材料浆料具有优异的性能，例如表现在浆料均匀，储存时间长，并且储存稳定性好。在经历长时间的储存之后，浆料的粘度保持不变，固体成分的沉降不明显。
此外，通过本发明的方法制得的负极材料浆料粘合力强，在重复 的充电/放电循环过程中，可以经受住负极活性材料(特别是硅基材料)的体积变化，从而可以提供具有优异的电化学性能(例如，循环性能和倍率性能)的负极和电池。
在本发明方法的一些实例中，步骤a)的干混时间可以为30秒至30分钟，优选2-10分钟，更优选2-5分钟。
在本发明方法二的一些实例中，碱金属氢氧化物水溶液的制备时间(方法二的步骤b))可以为1-30分钟。
在本发明方法的一些实例中，浆料制备时间(方法一的步骤b)或方法二的步骤c))可以为不超过2小时，优选不超过1.5小时，更优选不超过1小时。
对用于本发明的聚丙烯酸(PAA)、碱金属氢氧化物、碱土金属氢氧化物、硅基材料以及碳材料的种类、形状、粒径和含量均没有特殊要求。
本文中，负极材料中所有物料的干重之和为100重量％。
在本发明方法的一些实例中，聚丙烯酸(PAA)、碱金属氢氧化物、碱土金属氢氧化物、硅基材料以及碳材料中的一种或多种，优选全部，为颗粒状和/或粉末状，或者被研磨成颗粒状和/或粉末状。
“硅基材料”指的是含硅的材料。已知用于锂离子电池或固态电池中的硅基材料或含硅材料均可用于本发明。硅基材料主要用作电池负极的活性材料。本文所用的术语“活性材料”是指在重复的充电/放电循环过程中，能够使锂嵌入/脱嵌的材料。
在一些实例中，硅基材料可以选自硅、硅合金、硅氧化物、硅/碳复合物和它们的组合。在一些实例中，硅合金可以包含硅和选自钛、锡、铝、锑、铋、砷、锗和铅中的一种或多种金属。在一些实例中，硅氧化物可以是硅的多种氧化物的混合物，例如，硅氧化物可以由SiOx表示，x的平均值为约0.5至约2。
对硅基材料的粒径没有特别限制，常见的硅基材料的粒径都适用本发明。在一些实例中，硅基材料的粒径可以是纳米级(即，从大于等于1纳米至小于1微米)或微米级(即，从大于等于1微米至小于1 毫米)。在一些实例中，硅基材料的粒径可以是30nm至15μm，例如100nm至3μm。
在一些实例中，基于负极材料的总干重，硅基材料的含量可以为5-88重量％，优选10-50重量％。硅基材料的含量大于或等于5重量％，可以改善电池的容量；硅基材料的含量小于或等于88重量％，可以改善电池的循环性能。
“碳材料”指的是含碳元素的材料。在本文中，碳材料主要用于改善电池负极的导电性和分散性，和/或用作填料。在一些实例中，碳材料可以选自炭黑、石墨、石墨烯、乙炔黑、科琴黑、碳纳米管、碳纳米纤维和它们的组合。炭黑优选超导电炭黑(例如，购自Timcal公司的Super P，粒径例如为20nm)。石墨优选石墨粉末(例如，粒径为大约1-30μm)和/或片状石墨(例如，购自Timcal公司的KS6L，粒径例如为大约6μm)。这些碳材料可以单独使用或者以任意组合使用。在一些实例中，可以同时使用超导电炭黑、石墨粉末和片状石墨(例如，KS6L)中的两种或三种。超导电炭黑的粒径较小并且导电性能好，有助于改善负极材料的一维导电性和一维分散性。石墨粉末和片状石墨的粒径较大并且导电性能好，有助于改善负极材料的二维导电性、二维分散性和循环性能，同时还可以用作填料。
在一些实例中，基于负极材料的总干重，碳材料的总含量可以为0-80重量％，优选10-80重量％，更优选10-70重量％。碳材料的总含量位于这些范围内，可以有利地改善负极材料的导电性、分散性和循环性能。
含水溶剂可以为水，或者为水和与水混溶的溶剂的混合物。在一些实例中，含水溶剂为水。在一些实例中，含水溶剂为水和与水混溶的溶剂的混合物。与水混溶的溶剂可以为醇，例如C1-C6线性醇，优选乙醇、正丙醇、异丙醇或它们的组合。
在一些实例中，含水溶剂的重量与负极材料的总干重之比为0.6:1至2:1。这样的比例有助于颗粒材料或干粉材料均匀混合，从而形成稳定的浆料或悬浮体。
如前所述，聚丙烯酸与碱金属氢氧化物和/或碱土金属氢氧化物 可以在含水溶剂的存在下发生化学反应，生成聚丙烯酸的碱金属盐和/或碱土金属盐。得到的聚丙烯酸的碱金属盐和/或碱土金属盐可以用作负极材料的粘合剂。在一些实例中，基于负极材料的总干重，聚丙烯酸(PAA)的用量可以为5-15重量％，优选8-10重量％。在一些实例中，聚丙烯酸中的羧基与所述碱金属氢氧化物和/或碱土金属氢氧化物中的氢氧根的总量的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
在本发明方法一的一些实例中，碱金属氢氧化物和/或碱土金属氢氧化物包含氢氧化锂或者为氢氧化锂，并且，在步骤a)中，被干混的物质还包含碳酸锂。在一些实例中，碳酸锂中的锂离子与聚丙烯酸中的羧基的摩尔比为0.0001:1至0.2:1。
在方法一的步骤a)中还添加有碳酸锂的情况下，通过本发明的方法一制得的负极材料浆料含有聚丙烯酸锂与碳酸锂形成的复合物，这里，聚丙烯酸锂与碳酸锂的复合物用作负极材料的粘合剂。
已知在锂离子电池中，锂会与电解液中的溶剂(例如碳酸酯)发生反应，从而形成固体硅基材料与液体电解质之间的界面(即固体-电解质界面，solid-electrolyte interphase，缩写为SEI)，碳酸锂是SEI的主要成分。SEI的形成会消耗锂并且电池内阻会增加，进而引起离子导电性的损失和电池容量急剧下降。因此，迄今为止，研究人员提出了很多种方法来避免固体-电解质界面的出现。
根据本发明的方法一，如果在步骤a)中添加有碳酸锂，在最终形成的负极材料中，硅基材料被碳酸锂包覆。与传统意义上避免固体-电解质界面的提议相反，本发明的方法实际上特意提供了固体-电解质界面。本发明的发明人出人意料地发现，通过在方法一的步骤a)中另外添加碳酸锂，可以实现很多意想不到的效果：
例如，首先，可以减少或避免电解液中溶剂的分解和钝化，从而可以减少由其带来的初始可逆容量，增加电池的初始库仑效率；并且可以避免在充电/放电循环中产生气体。
另外，与现有技术中极力避免的不均匀、松散且绝缘的固体-电解质界面相比，本发明通过主动加入碳酸锂，可以在硅基材料表面形 成均匀、紧致的碳酸锂，并且，可以抑制固体-电解质界面的形成，从而减小内阻和增强离子导电性。碳酸锂固体-电解质界面不溶于电解液的溶剂(例如碳酸酯)中，从而可以持久保持碳酸锂固体-电解质界面的均匀性、以及电解液的稳定性和纯净度。而且，碳酸锂固体-电解质界面还可以将硅基材料与电解液隔开，从而防止硅基材料与电解液之间发生不期望的反应。同时，碳酸锂作为锂源，还可以在连续的充电/放电循环中减少对电解液中锂离子的消耗。
此外，本发明将碳酸锂加入到负极材料中，而不是加入到电解液中。如果将碳酸锂添加到电解液中的话，需要预先将碳酸锂制备成水溶液，然后将碳酸锂水溶液添加到电解液中，最后还需要从电解液中除去水，工序复杂，成本高昂。本发明将固态碳酸锂直接加入到负极材料中，避免了上述缺点。
[锂离子电池和固态电池]
本发明还提供了一种锂离子电池，其包含负极，所述负极由根据本发明的前述方法制得的负极材料制备。
本发明还提供了一种固态电池，其包含负极，所述负极由根据本发明的前述方法制得的负极材料制备。
除了上述负极之外，锂离子电池还可以包含正极、隔膜和电解液。
除了上述负极之外，固态电池还可以包含正极和电解质，以及任选存在的隔膜。
对锂离子电池和固态电池的正极材料没有特殊要求，已知用于锂离子电池的正极材料都可用于本发明。在一些实例中，正极可以使用锂基正极。在锂基正极的非限制性实例中，可以包括金属锂；锂合金，例如锂-铟合金；锂与一种或多种其他金属的层合物，例如锂-铟层合物；以及它们的任意组合。
在锂离子电池的一些实例中，电解液可以通过使锂盐溶于有机溶剂中得到。对锂盐没有特殊限制，已知可用于锂离子电池的那些锂盐均可用于本发明。合适的有机溶剂可以是碳酸酯。可用于本发明的碳酸酯包括但不限于环状碳酸酯，例如碳酸亚乙酯(EC)、碳酸亚丙酯、 氟代亚乙基碳酸酯(FEC)和二氟代亚乙基碳酸酯等；线性碳酸酯，例如碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯以及它们的氟化物；以及以上物质的任意组合。
对锂离子电池和固态电池中的隔膜没有特殊要求，已知用于锂离子电池或固态电池的隔膜都可用于本发明。在一些实例中，隔膜可以由以下物质制成：聚烯烃，例如聚乙烯、聚丙烯和聚丁烯；聚酯，例如聚对苯二甲酸乙二醇酯。隔膜可以是多孔膜或者多孔片材的形式。隔膜可以是单层的，也可以是双层或者更多层的层合物。
在本发明的固态电池中，电解质是固态的。常用于固态电池的电解质都可以用于本发明，只要这些电解质是可以传导锂离子的材料即可。例如，固态电解质可以是聚环氧乙烷(PEO)、可以传导锂离子的硫化物、可以传导锂离子的氯化物、或者这些物质的组合。固态电解质可以是单层的，也可以是两层或更多层的层合物。
此外，本发明的锂离子电池或固态电池中可以任选包含其他的添加剂，只要这些添加剂不会不利地影响电池的电化学性能即可。所述其他的添加剂(如果存在的话)，可以被包含在正极、负极、电解液、固态电解质和/或隔膜之中或者之间。
对集流体没有特别限制，已知用于锂离子电池或固态电池的集流体均可用于本发明中。在一些实例中，正极集流体可以是铝箔。在一些实例中，负极集流体可以是镍箔或涂布有镍的铜箔。本发明的发明人出人意料地发现，通过采用镍箔或涂布有镍的铜箔作为负极集流体，负极材料与负极集流体之间的粘合力很强，从而在连续的充电/放电循环中，可以保持负极和整个电池的完整性，改善电池的电化学性能，特别是循环性能和倍率性能。
本发明的锂离子电池和固态电池可以用于储能系统或者电动车辆中。
实施例
[材料]
纳米硅：负极活性材料，粒径50nm，购自Sigma-Aldrich。
超导电炭黑(Super P)：碳材料，粒径约为20nm，购自Timcal公司。KS6L：片状石墨，碳材料，粒径约为6μm，购自Timcal公司。
石墨粉末：碳材料，粒径2-10μm，购自深圳科晶智达科技有限公司。PAA：聚丙烯酸，用于形成粘合剂，体积平均分子量(Mv)：约450,000，购自Aldrich公司。
Celgard 2325：隔膜，聚丙烯-聚乙烯薄膜(PP/PE)，购自深圳科晶智达科技有限公司。
[负极材料的制备]
实施例1
如图4所示，在室温和常压下，称量2g Super P并加到铂富粉料混合机(BBL800搅拌机，购自广州市博裕贸易有限公司)中，以所述混合机允许的最高速度(约1000rpm)搅拌约1分钟。然后，依次向铂富粉料混合机中加入18g纳米硅、20g KS6L、50g石墨粉末、7g PAA和3g LiOH·H2O，在每个加料间隔都以所述混合机允许的最高速度搅拌约1分钟，得到100g干混合物。
对干混合物取样并将样品置于两片2mm×6mm的透明玻璃板之间，目测样品中是否有白点或颗粒。如果样品有白点或颗粒的话，就以所述混合机允许的最高速度将混合机中的干混合物继续搅拌1分钟。如果样品中没有白点并且样品是均匀粉末的话，直接进入下面的浆料制备步骤。
然后，在真空搅拌机(CA-40真空搅拌机，购自广州市浩美设备有限公司)中加入100g水。在以500rpm的速度搅拌的同时，向水中加入干混合物，并将搅拌速度调整为900rpm，继续搅拌20分钟。然后，将搅拌速度调整为2500rpm，继续搅拌30分钟。然后，将搅拌速度调整为700rpm，并且将压力从常压调整为真空，继续搅拌20分钟，得到负极材料浆料。
实施例2
如图5所示，在室温和常压下，称量2g Super P并加到铂富粉料 混合机(BBL800搅拌机，购自广州市博裕贸易有限公司)中，以所述混合机允许的最高速度(约1000rpm)搅拌约1分钟。然后，依次向铂富粉料混合机设备中加入18g纳米硅、20g KS6L、50g石墨粉末和7g PAA，在每个加料间隔都以所述混合机允许的最高速度搅拌约1分钟，得到97g干混合物。
对干混合物取样并将样品置于两片2mm×6mm的透明玻璃板之间，目测样品中是否有白点或颗粒。如果样品中有白点或颗粒的话，就以所述混合机允许的最高速度将混合机中的干混合物继续搅拌1分钟。如果样品中没有白点并且样品是均匀粉末的话，直接进入下面的浆料制备步骤。
然后，在真空搅拌机(CA-40真空搅拌机，购自广州市浩美设备有限公司)中加入100g水。在以500rpm的速度搅拌的同时，向水中加入干混合物，并将搅拌速度调整为900rpm，继续搅拌20分钟。向得到的混合物中加入预先制备的10g 30％NaOH水溶液，然后，将搅拌速度调整为2500rpm，继续搅拌30分钟。然后，将搅拌速度调整为700rpm，并且将压力从常压调整为真空，继续搅拌20分钟，得到负极材料浆料。
实施例3
以与实施例1相同的方式制备负极材料浆料，除了在加入3g LiOH·H2O之后，再加入0.5g Li2CO3，从而得到100.5g干混合物。
对比例1
如图6所示，在室温和常压下，在真空搅拌机(CA-40真空搅拌机，购自广州市浩美设备有限公司)中加入90g水。在以1000rpm的速度搅拌的同时，将7g PAA加入水中，以1000rpm的速度继续搅拌10小时，得到PAA的水溶液。向PAA的水溶液中加入3g LiOH，保持1000rpm的速度再搅拌2小时，得到LiPAA的水溶液。然后，以1000rpm的速度继续搅拌约30分钟。然后，保持以1000rpm的速度搅拌，并依次向LiPAA的水溶液中加入3g Super P、18g纳米硅、 20g KS6L和50g石墨粉末，在每个加料间隔都搅拌约30分钟。加料完毕后，将搅拌速度调整为700rpm，并且将压力从常压调整为真空，继续搅拌20分钟，得到负极材料浆料。整个制备过程耗时约14小时20分钟。
[极片的制备]
将实施例1-3、以及对比例1得到的负极材料浆料分别涂布到铜箔上，然后经涂布的铜箔置于真空烘箱(德国宾得VDL鼓风干燥箱)中，在约60℃和真空下干燥约8小时。用EQ-T-06电池极片冲片机(购自深圳市威智达光电科技有限公司)将经干燥的铜箔冲压成多个Φ12mm的负极极片。由此得到的负极极片将用于后面的锂离子电池的制备实验、极片的均匀性测试和极片的粘合力测试。
[锂离子电池的制备]
在填充有氩气的手套箱(MB-10compact,MBraun)中，采用如上所述制备的各种负极极片组装扣式电池(CR2016)。将锂金属箔用作对电极。将1M LiPF6在FEC/EC/DMC(体积比为1:5:5的氟代亚乙基碳酸酯(FEC)、碳酸亚乙酯(EC)和碳酸二甲酯(DMC)的混合物)中的溶液用作电解液。将Celgard 2325用作隔膜。由此制得的锂离子电池用于后面根据图7的电化学性能测试。
类似地，采用相同方法制备锂离子电池，除了采用镍钴锰酸锂代替锂金属箔。由此制得的锂离子电池用于后面根据图8的电化学性能测试。
[性能测试]
[浆料的储存稳定性]
分别对实施例1和对比例1得到的负极浆料取样。在流变计Anton PaarRheometer MCR 52(购自奥地利安东帕有限公司上海代表处)中，以70s-1的剪切速率测定样品的粘度。在1天、2天、5天和7天之后，分别测量样品的粘度，并将结果记录在下表1中。
表1
Figure PCTCN2016084786-appb-000001
从表1清楚可见，在2天以后直至7天之后，实施例1的样品粘度几乎保持不变，而对比例1的样品粘度持续降低。因此，根据本发明方法制备的负极材料浆料的储存时间长，并且储存稳定性好。
[极片的均匀性]
对由实施例1和对比例1的负极材料浆料制得的极片进行均匀性测试。每个测试各取24个极片，分别测量这24个极片的重量和厚度，并根据以下样本标准偏差公式计算极片的重量偏差和厚度偏差，计算结果记录在下表2中。
Figure PCTCN2016084786-appb-000002
其中，S表示重量偏差或厚度偏差；
N为24；
Xi，即X1、X2、……直至X24，表示24个极片各自的重量或厚度；
Figure PCTCN2016084786-appb-000003
代表所采用的24个极片的重量平均值或厚度平均值。
表2
  重量标准偏差 厚度标准偏差
对比例1 6％ 4％
实施例1 3％ 2％
从表2清楚可见，实施例1的极片的重量和厚度都比对比例1的样品均匀。
[极片的粘合力]
采用FMT-310测力计(购自ALLURIS公司)来测量由实施例1和对比例1的负极材料浆料制得的极片的粘合力。每个测试各取3个极片，对3个极片测得的粘合力取平均值，将该平均值记录为极片的粘合力。具体地，在每个极片的涂布有浆料的一侧粘附2cm宽的透明胶带，将粘附有透明胶带的极片固定在测力计的上下两个固定端。以100毫米/分钟的速度垂直于极片表面匀速拉动胶带，缓慢增加拉力，胶带开始被拉动时的拉力值即为测得的极片的粘合力(单位：N/m)。
表3
Figure PCTCN2016084786-appb-000004
从表3可见，实施例1的样品的粘合力显著优于对比例1的样品。
[锂离子电池的电化学性能]
图7比较了采用对比例1、实施例1和实施例3的负极浆料制备的电池在1C的电流密度下的充电/放电性能，其中，各电池采用锂金属箔作为对电极。
在Arbin电池测试系统(购自Arbin Corporation公司)中，于25℃测试各电池的循环性能。在0.01-0.9V(vs Li/Li+)的电压范围内，使各电池在0.1C进行第1个充电/放电循环，在0.3C进行第2个和第3个充电/放电循环，以及在1C进行其余的充电/放电循环。各负极中 的总负载量均为约7mg/cm2。
由图7可见，由实施例1干法混合的负极材料浆料得到的电池比采用对比例1湿法混合的负极材料浆料得到的电池具有更好的循环性能。与实施例1相比，实施例3额外添加了Li2CO3，进一步改善了电池的循环性能。
图8比较了采用实施例1、实施例2和实施例3的负极材料浆料制备的电池在1C的电流密度下的充电/放电性能，其中，各电池采用镍钴锰酸锂作为对电极。
在Arbin电池测试系统(购自Arbin Corporation公司)中，于25℃测试各电池的循环性能。在2.5-4.2V(正极镍钴锰酸锂)的电压范围内，使各电池在0.1C进行第1个充电/放电循环，在0.3C进行第2个和第3个充电/放电循环，以及在1C进行其余的所有充电/放电循环，除了在0.1C进行第51个、第101个、第151个和第201个充电/放电循环。各负极中的总负载量均为约7mg/cm2。
由图8可见，实施例1、实施例2和实施例3均通过干法混合得到负极材料浆料。实施例2采用NaPAA作为负极粘结剂，由此得到的电池比实施例1采用LiPAA作为负极粘结剂得到的电池具有更好的循环性能。与实施例1相比，实施例3额外添加了Li2CO3，进一步改善了电池的循环性能。
本文中描述了本发明的优选实施方案，包括发明人已知的用于实施要求保护的主题的最佳方式。对于本领域技术人员来说，当阅读前述说明时，那些优选实施方案的变体可变得显而易见。发明人预期本领域技术人员能恰当地使用此类变体，并且发明人意欲使本发明能以有别于本文中具体描述的方式实践。因此，本发明包括可适用的方法所允许的本文所附权利要求中所述主题的所有修改和等效形式。此外，除非本文另外指明或者上下文明显矛盾，否则本发明涵盖其所有可能的变体中上述因素的任何组合。

Claims (12)

  1. 制备电池的负极材料的方法，其包括以下步骤：
    a)在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：
    聚丙烯酸，
    硅基材料，和
    碱金属氢氧化物和/或碱土金属氢氧化物，和
    任选存在的碳材料；以及
    b)将步骤a)得到的干混合物与含水溶剂混合，从而得到所述负极材料。
  2. 根据权利要求1的方法，其中所述碱金属氢氧化物和/或碱土金属氢氧化物选自氢氧化锂、氢氧化钠、氢氧化钾、氢氧化钙和它们的组合，优选氢氧化锂；优选地，聚丙烯酸中的羧基与所述碱金属氢氧化物和/或碱土金属氢氧化物中的氢氧根的总量的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
  3. 根据权利要求1或2所述的方法，其中所述碱金属氢氧化物和/或碱土金属氢氧化物包含氢氧化锂，并且，在步骤a)中，被干混的物质还包含碳酸锂；优选地，碳酸锂中的锂离子与聚丙烯酸中的羧基的摩尔比为0.0001:1至0.2:1。
  4. 制备电池的负极材料的方法，其包括以下步骤：
    a)在不添加任何溶剂的情况下，将以下组分干混，从而得到干混合物：
    聚丙烯酸，
    硅基材料，和
    任选存在的碳材料；
    b)将碱金属氢氧化物与水混合，从而得到碱金属氢氧化物的水溶液；以及
    c)将步骤a)得到的干混合物、步骤b)得到的碱金属氢氧化物的水溶液和任选存在的含水溶剂混合，从而得到所述负极材 料。
  5. 根据权利要求4的方法，其中所述碱金属氢氧化物选自氢氧化锂、氢氧化钠、氢氧化钾和它们的组合，优选氢氧化钠；优选地，聚丙烯酸中的羧基与所述碱金属氢氧化物中的氢氧根的摩尔比是0.2:1至1.5:1，优选0.8:1至1.2:1。
  6. 根据前述权利要求中任一项所述的方法，其中步骤a)的干混时间为30秒至30分钟，优选2-10分钟，更优选2-5分钟。
  7. 根据前述权利要求中任一项所述的方法，其中所述硅基材料选自硅、硅合金、硅氧化物、硅/碳复合物和它们的组合。
  8. 根据前述权利要求中任一项所述的方法，其中所述碳材料选自炭黑、石墨、石墨烯、乙炔黑、科琴黑、碳纳米管、碳纳米纤维和它们的组合；炭黑优选超导电炭黑；和/或石墨优选石墨粉末、片状石墨或它们的组合。
  9. 根据前述权利要求中任一项所述的方法，其中所述含水溶剂为水、或者为水和与水混溶的溶剂的混合物；所述含水溶剂优选水；所述与水混溶的溶剂优选醇，更优选C1-C6线性醇，最优选乙醇、正丙醇、异丙醇或它们的组合。
  10. 锂离子电池，其包含负极，所述负极由根据权利要求1-9中任一项所述的方法制得的负极材料制备。
  11. 固态电池，其包含负极，所述负极由根据权利要求1-9中任一项所述的方法制得的负极材料制备。
  12. 根据权利要求10或11的电池，其中所述负极还包含负极集流体，所述负极集流体是镍箔或涂布有镍的铜箔。
PCT/CN2016/084786 2016-06-03 2016-06-03 电池的负极材料的制备方法、锂离子电池和固态电池 WO2017206181A1 (zh)

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