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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
  • H01M4/362—Composites
• • H—ELECTRICITY
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  • 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
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  • 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
• • 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
  • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• • H—ELECTRICITY
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  • 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
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  • 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
  • H01M4/38—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
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
• • 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
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the invention belongs to the field of lithium ion battery electrodes, and particularly relates to a microcapsule type silicon carbon composite anode material, a preparation method thereof and application thereof.
• the silicon material has a high lithium storage capacity, its theoretical capacity is about 4200 mAh / g, and the actual specific capacity is more than 3000 mAh / g, which is very likely to replace graphite materials as an important negative electrode material for the next generation of high-energy lithium batteries.
• silicon materials undergo a drastic change in the volume of silicon ions during the insertion and extraction of lithium ions, and the expansion ratio can reach 300%, thereby causing the silicon particles to be powdered.
• the problem of rapid decline in the capacity of the pole piece is that the first Coulomb efficiency of the silicon material is not high, and the third is that the stability of the SEI film on the silicon surface is poor, especially in the process of volume change, which causes damage and growth, resulting in serious lithium consumption.
• the modification and modification of silicon materials including the particle size control of silicon materials, surface control and compounding with carbon materials
• the second is to select suitable bonding.
• Agent system especially the selection of binder system with three-dimensional network type cross-linking structure, including cross-linked alginate system, cross-linked polyacrylamide system, etc., the current research in this area has also achieved good results.
• the third is the choice of an excellent electrolyte system, especially the electrolyte system containing fluoroethylene carbonate (FEC) shows good performance.
• FEC fluoroethylene carbonate
• silicon-carbon composite In the prior art, one of the choices for industrial application of silicon materials is silicon-carbon composite.
• silicon-carbon composite there are many ways of silicon-carbon composite, including in-situ growth of carbon materials on the surface of silicon materials, including amorphous carbon, carbon nanotubes and Graphene, etc., but the preparation process of this material is very complicated, silicon oxide and silicon carbide are easily formed during the growth of carbon materials, affecting the performance of silicon materials, and the other is the mechanical mixing of silicon particles and carbon materials. It is easy to mix the two evenly, especially the mechanical mixing of silicon powder and graphite material has been industrialized. Generally, about 10% of silicon particles can be mixed in the graphite powder for the production of more than 400mAh/g capacity.
• Carbon negative electrode sheet although this manufacturing method is simple and easy to implement, the prominent problem is that the capacity of the electrode is rapidly attenuated. After about 200 cycles, the silicon material can hardly perform its proper performance, and the high specific energy battery The longevity of life has a great impact.
• the Chinese invention patent CN103022448A discloses a method for preparing a silicon battery silicon carbon negative electrode material, comprising the following steps: 1) 50 to 90 parts by weight of micron-sized silicon. The powder is added to the ball mill tank, and the solvent is added to perform ball milling. 2) 10 to 50 parts by weight of natural graphite is added to the step 1) ball-milled industrial silicon powder to continue the ball milling; 3) the step 2) the ball-milled material is dried.
• the technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an improved silicon-carbon composite anode material.
• the microcapsule-type silicon-carbon composite anode material of the invention has extremely excellent cycle performance, coulombic efficiency and rate performance. Excellent results.
• the present invention also provides a method of preparing a microcapsule-type silicon-carbon composite anode material.
• the invention also provides an application of a microcapsule type silicon carbon composite anode material in preparing a lithium ion battery electrode sheet.
• a microcapsule-type silicon-carbon composite anode material comprising a current collector, and a silicon carbon coating formed by drying a silicon carbon slurry coated on the current collector, the silicon carbon slurry comprising a carbonaceous slurry and a silicon capsule powder dispersed in the carbonaceous slurry, the carbonaceous slurry comprising a dispersant and a carbon material dispersed in the dispersant, a first conductive agent, and a first bond
• the silicon capsule powder comprises silicon powder and a second binder coated on the surface of the silicon powder, and the second binder and the silicon powder coated thereon form a microcapsule structure; The first binder is different from the second binder.
• the microcapsule structure is a solid particle or particle formed by coating a surface of the silicon powder with a second binder, wherein the solid particles or particles are made of silicon powder, and the second binder is coated with silicon powder. surface.
• the first binder and the second binder are insoluble, poorly soluble or slightly Dissolved.
• the first binder is sodium carboxymethylcellulose and/or styrene butadiene rubber
• the second binder is selected from the group consisting of alginate, polyacrylate, and Arabian. A combination of one or more of gum, guar gum, and hyaluronate.
• the second binder is a binder to which calcium ions and/or copper ions are added, wherein the mass fraction of calcium ions and/or copper ions to the second binder is 2 to 15%.
• the addition of copper ions and/or calcium ions can make the stability and mechanical properties of the outer shell formed by the binder better.
• other components capable of crosslinking the binder can also be added to obtain The modified binder enables the shell formed by the binder to have strong mechanical properties and stability.
• the second binder is a binder to which calcium ions and/or copper ions are added, wherein the calcium ion and/or copper ions account for 5 to 12% by mass of the second binder. .
• the weight ratio of the carbon material to the silicon powder is 2 to 10..1.
• the silicon powder and the second binder respectively occupy 70 to 95% and 2 to 15% by mass of the raw material of the silicon capsule powder.
• the carbon material, the first binder, and the first conductive agent respectively occupy 90 to 98%, 1 to 5% of the mass fraction of the carbonaceous slurry, and 0.5 to 5%.
• the silicon powder is nano-silicon and/or micro-silicon.
• the carbon material is a combination of one or more selected from the group consisting of natural graphite, artificial graphite, pyrolytic carbon, or hard carbon materials.
• the dispersing agent is water, or a mixed solvent of an alcohol and water.
• the first conductive agent is a combination of one or more selected from the group consisting of acetylene black, Super P, Super S, carbon fibers, carbon nanotubes, and graphene.
• the silicon capsule powder further comprises a second conductive agent selected from the group consisting of acetylene black, Super P, Super S, carbon fiber, carbon nanotubes, and A combination of one or more of graphene.
• Another technical solution provided by the present invention is a method for preparing a microcapsule-type silicon-carbon composite anode material according to the above, wherein the preparation method comprises the following steps:
• (a) preparation of a silicon capsule powder dispersing the silicon powder of the silicon capsule powder and the second binder in a dispersant to obtain a siliceous slurry, and then baking the siliceous slurry Drying, grinding, that is, the silicon capsule powder having a microcapsule structure in which the silicon powder is a core and the second binder is an outer shell; wherein a second conductive agent is added to the dispersing agent, or is not added;
• preparation of a silicon carbon slurry the silicon capsule powder prepared in the step (a) is added to the preparation prepared in the step (b) when the preparation of the carbonaceous slurry is completed, at the completion or after completion.
• the carbonaceous slurry is mixed and stirred to obtain the silicon carbon slurry;
• step (d) preparation of a microcapsule-type silicon-carbon composite anode material: the silicon carbon slurry prepared in the step (c) is coated on the current collector, and dried to obtain the microcapsule-type silicon-carbon composite anode material.
• a microcapsule-type silicon-carbon composite anode material described above is used for preparing a lithium ion battery electrode sheet.
• the present invention has the following advantages compared with the prior art:
• the silicon powder and the carbon material are respectively placed in different binder environments, and the silicon powder is completely coated by the second binder to form a microcapsule structure, so that the activities of silicon and carbon are maximized.
• the long-term cycle performance of the electrode sheet is greatly improved, and the original 200-time significant attenuation is increased to almost no attenuation, the internal resistance of the electrode sheet is significantly reduced, the rate performance is greatly improved, and the mechanical stability of the electrode sheet is remarkably improved.
• the first coulombic efficiency of the electrode sheet is greatly improved, and therefore the silicon carbon negative electrode material of the present invention is of great significance for the development of future high specific energy and long life lithium ion batteries.
• the present invention proposes a silicon-carbon composite anode material having a microcapsule structure, and in particular, firstly, a binder suitable for silicon particles is mixed and dispersed together with silicon particles in silicon.
• the surface of the particle is uniformly coated with a binder having good compatibility, and the stability of the binder is preferably further strengthened by a crosslinking technique to form a binder which is modified by crosslinking with silicon particles as a core.
• the microcapsule structure of the outer shell is further based on the preparation of the basic carbon fiber (graphite) slurry, and the silicon capsule powder is added and stirred to uniformly disperse the silicon capsule powder in the carbonaceous slurry, thus forming a Silicon in a suitable binder for silicon, carbon in a binder suitable for carbon (preferably between the two different binders is insoluble, poorly soluble or slightly soluble, but without a distinct phase interface)
• the silicon carbon slurry is formed, and then the silicon carbon slurry is coated on the current collector, and dried to obtain a microcapsule type silicon-carbon composite anode material, which can be processed into an electrode sheet for a lithium ion battery, and the electrode sheet protrudes.
• the preparation method of the silicon-carbon composite negative electrode material of the microcapsule structure of the invention comprises the following steps: (a) using silicon powder (using a common nano or micro silicon powder for a lithium battery), a second binder, and a second conductive agent. (preferably, or not) dispersed in a dispersant, stirred and mixed to obtain a siliceous slurry, and then the siliceous slurry is dried at a suitable temperature (preferably 60 to 90 ° C), and then ground.
• the silicon powder is a core
• the second binder is a microcapsule structure of the silicon capsule powder
• the second binder is selected from the group consisting of alginate, polyacrylate, gum arabic, melon a mixture of one or more of guar gum and hyaluronic acid salt
• the first binder is selected from the group consisting of sodium carboxymethylcellulose and/or styrene-butadiene rubber
• the silicon capsule is added when the preparation of the carbonaceous slurry is about to be completed, when it is completed, or after completion.
• the powder is further stirred for about 30 minutes to obtain a silicon carbon slurry; (d) the obtained silicon carbon slurry is applied to the current collecting In a body, the coating thickness is preferably 40 to 200 ⁇ m, and drying (preferably 60 ° C), that is, a microcapsule-type silicon-carbon composite negative electrode material is obtained.
• a second binder rich in carboxyl or hydroxyl groups which is advantageous for film formation on the silicon surface to improve the first coulombic efficiency of the material.
• the second binder is added with calcium ions.
• a binder of copper ions wherein the calcium ion and/or copper ion accounts for 2 to 15% by mass of the second binder, more preferably, wherein calcium ions and/or copper ions account for
• the mass fraction of the second binder is 5 to 12%, and the copper ions and/or calcium ions are added in the form of CaCl 2 , CaSO 4 , CuCl 2 , CuSO 4 , etc., and further crosslinking of the binder not only reduces the The possibility of dissolving in the carbonaceous slurry can also inhibit the volume effect of silicon during the cycle. When it is mixed with the carbonaceous slurry, the silicon and carbon can be in the best binder environment. It is beneficial to improve the electrical properties of the electrode sheets.
• the first and second conductive agents are each a mixture of one or more selected from the group consisting of acetylene black, Super P, Super S, carbon fibers, and carbon nanotubes; and the dispersing agents used in the steps (a) and (b) can be used. It is a mixed solvent of water, or water and an alcohol solvent. Wherein, the weight ratio between the carbon material and the silicon powder is controlled to be 2 to 10..1, and the silicon powder and the second binder respectively account for 70 to 95%, 2 to 15 of the mass of the silicon capsule powder.
• the silicon capsule powder further comprises a second conductive agent in a mass fraction of 0.01 to 15% of the silicon capsule powder; the carbon material, the second binder, and the second conductive agent
• the mass fraction of the carbonaceous slurry is 90 to 98%, 1 to 5%, and 0.5 to 5%, respectively.
• This embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method:
• the obtained microcapsule-type silicon-carbon composite anode material is made into a negative electrode sheet, and a lithium sheet is used as a counter electrode to assemble a 2032 button type battery.
• the electrolyte is 1M LiPF 6 is a conductive salt having a volume ratio of 1:1:1. /DMC/DEC solution, and add FEC which accounts for 10% of the electrolyte as an additive; seal the assembled battery, and after standing, test the electrochemical performance of the constant current on the charge and discharge tester (where the charge and discharge rates are both It is 0.2C and the voltage range is 0.01 ⁇ 1V).
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in the embodiment 1, except that in the step (a), the silicon powder and the seaweed
• the mass ratio of sodium and acetylene black is 85:15:0.
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (a), the second The binder is a binder to which calcium ions are added, wherein calcium ions are added by calcium chloride, and the mass ratio of calcium ions to sodium alginate added is 2..25.
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (a), the second The binder is a binder to which copper ions are added, wherein copper ions are added by means of copper sulfate, and the mass ratio of the added copper ions to sodium alginate is 1..10.
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (a), the second step is adopted.
• the mass ratio of the binder gum arabic, silicon powder, gum arabic and acetylene black is 85:10:5.
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (a), the second step is adopted.
• the binder is guar gum, the mass ratio of silicon powder, guar gum and acetylene black is 80:10:10; in step (b), the first binder used is sodium carboxymethylcellulose and A mixture of styrene butadiene rubber emulsions.
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (a), the second step is adopted.
• the binder is sodium hyaluronate, the mass ratio of silicon powder, sodium hyaluronate and acetylene black is 75:15:10; in step (b), the first binder used is sodium carboxymethylcellulose and A mixture of styrene butadiene rubber emulsions.
• the present embodiment provides a microcapsule-type silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (c), graphite and silicon are controlled.
• the weight ratio of the powder is 4:1.
• the present embodiment provides a silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (a), sodium alginate is not added, but Add the same amount of sodium carboxymethylcellulose.
• the present embodiment provides a silicon-carbon composite anode material, which is prepared by the following method, and the preparation steps thereof are basically the same as those in Embodiment 1, except that in step (b), carboxymethyl cellulose is not added. Sodium, but add the same amount of sodium alginate.

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• 2017
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