CN117038991A - Silicon-based negative electrode binder with topological three-dimensional structure, negative electrode sheet, preparation method of negative electrode sheet and battery - Google Patents
Silicon-based negative electrode binder with topological three-dimensional structure, negative electrode sheet, preparation method of negative electrode sheet and battery Download PDFInfo
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- CN117038991A CN117038991A CN202311155189.7A CN202311155189A CN117038991A CN 117038991 A CN117038991 A CN 117038991A CN 202311155189 A CN202311155189 A CN 202311155189A CN 117038991 A CN117038991 A CN 117038991A
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 68
- 239000010703 silicon Substances 0.000 title claims abstract description 68
- 239000011883 electrode binding agent Substances 0.000 title claims abstract description 21
- 238000002360 preparation method Methods 0.000 title abstract description 14
- 229920000642 polymer Polymers 0.000 claims abstract description 50
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 16
- 238000011065 in-situ storage Methods 0.000 claims abstract description 7
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 5
- 239000011230 binding agent Substances 0.000 claims description 35
- 229920002125 Sokalan® Polymers 0.000 claims description 20
- 239000004584 polyacrylic acid Substances 0.000 claims description 19
- 229920000858 Cyclodextrin Polymers 0.000 claims description 15
- 238000001035 drying Methods 0.000 claims description 12
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 claims description 9
- 239000001263 FEMA 3042 Substances 0.000 claims description 9
- LRBQNJMCXXYXIU-PPKXGCFTSA-N Penta-digallate-beta-D-glucose Natural products OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-PPKXGCFTSA-N 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 229920002258 tannic acid Polymers 0.000 claims description 9
- LRBQNJMCXXYXIU-NRMVVENXSA-N tannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-NRMVVENXSA-N 0.000 claims description 9
- 229940033123 tannic acid Drugs 0.000 claims description 9
- 235000015523 tannic acid Nutrition 0.000 claims description 9
- 239000011884 anode binding agent Substances 0.000 claims description 8
- 239000005543 nano-size silicon particle Substances 0.000 claims description 8
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 7
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 7
- HFHDHCJBZVLPGP-UHFFFAOYSA-N schardinger α-dextrin Chemical class O1C(C(C2O)O)C(CO)OC2OC(C(C2O)O)C(CO)OC2OC(C(C2O)O)C(CO)OC2OC(C(O)C2O)C(CO)OC2OC(C(C2O)O)C(CO)OC2OC2C(O)C(O)C1OC2CO HFHDHCJBZVLPGP-UHFFFAOYSA-N 0.000 claims description 7
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 7
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- 229920000615 alginic acid Polymers 0.000 claims description 4
- 229960001126 alginic acid Drugs 0.000 claims description 4
- 229920002907 Guar gum Polymers 0.000 claims description 3
- HTTJABKRGRZYRN-UHFFFAOYSA-N Heparin Chemical compound OC1C(NC(=O)C)C(O)OC(COS(O)(=O)=O)C1OC1C(OS(O)(=O)=O)C(O)C(OC2C(C(OS(O)(=O)=O)C(OC3C(C(O)C(O)C(O3)C(O)=O)OS(O)(=O)=O)C(CO)O2)NS(O)(=O)=O)C(C(O)=O)O1 HTTJABKRGRZYRN-UHFFFAOYSA-N 0.000 claims description 3
- IMQLKJBTEOYOSI-GPIVLXJGSA-N Inositol-hexakisphosphate Chemical compound OP(O)(=O)O[C@H]1[C@H](OP(O)(O)=O)[C@@H](OP(O)(O)=O)[C@H](OP(O)(O)=O)[C@H](OP(O)(O)=O)[C@@H]1OP(O)(O)=O IMQLKJBTEOYOSI-GPIVLXJGSA-N 0.000 claims description 3
- IMQLKJBTEOYOSI-UHFFFAOYSA-N Phytic acid Natural products OP(O)(=O)OC1C(OP(O)(O)=O)C(OP(O)(O)=O)C(OP(O)(O)=O)C(OP(O)(O)=O)C1OP(O)(O)=O IMQLKJBTEOYOSI-UHFFFAOYSA-N 0.000 claims description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 3
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- 239000000665 guar gum Substances 0.000 claims description 3
- 235000010417 guar gum Nutrition 0.000 claims description 3
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- 229960002897 heparin Drugs 0.000 claims description 3
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- 229940068041 phytic acid Drugs 0.000 claims description 3
- 235000002949 phytic acid Nutrition 0.000 claims description 3
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- 229920001690 polydopamine Polymers 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 3
- 229940068984 polyvinyl alcohol Drugs 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 239000008107 starch Substances 0.000 claims description 3
- 229940032147 starch Drugs 0.000 claims description 3
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- 239000000853 adhesive Substances 0.000 abstract description 22
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- 230000008569 process Effects 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 14
- 239000000243 solution Substances 0.000 description 14
- 239000001116 FEMA 4028 Substances 0.000 description 11
- WHGYBXFWUBPSRW-FOUAGVGXSA-N beta-cyclodextrin Chemical compound OC[C@H]([C@H]([C@@H]([C@H]1O)O)O[C@H]2O[C@@H]([C@@H](O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O3)[C@H](O)[C@H]2O)CO)O[C@@H]1O[C@H]1[C@H](O)[C@@H](O)[C@@H]3O[C@@H]1CO WHGYBXFWUBPSRW-FOUAGVGXSA-N 0.000 description 11
- 235000011175 beta-cyclodextrine Nutrition 0.000 description 11
- 229960004853 betadex Drugs 0.000 description 11
- 239000002131 composite material Substances 0.000 description 11
- 229910052739 hydrogen Inorganic materials 0.000 description 11
- 239000001257 hydrogen Substances 0.000 description 11
- VYFYYTLLBUKUHU-UHFFFAOYSA-N dopamine Chemical compound NCCC1=CC=C(O)C(O)=C1 VYFYYTLLBUKUHU-UHFFFAOYSA-N 0.000 description 10
- 239000010405 anode material Substances 0.000 description 7
- 238000005886 esterification reaction Methods 0.000 description 7
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
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- 239000002210 silicon-based material Substances 0.000 description 5
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 4
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- 229910052744 lithium Inorganic materials 0.000 description 4
- 230000001681 protective effect Effects 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 125000000524 functional group Chemical group 0.000 description 3
- 230000036961 partial effect Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical group CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
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- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 230000016615 flocculation Effects 0.000 description 2
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- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 2
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- 239000000463 material Substances 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
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- 230000002441 reversible effect Effects 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000011856 silicon-based particle Substances 0.000 description 2
- 239000000661 sodium alginate Substances 0.000 description 2
- 235000010413 sodium alginate Nutrition 0.000 description 2
- 229940005550 sodium alginate Drugs 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241001025261 Neoraja caerulea Species 0.000 description 1
- 238000005411 Van der Waals force Methods 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- 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
-
- 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
- H01M4/134—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
-
- 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
Abstract
The invention discloses a topological three-dimensional structure silicon-based negative electrode binder, which comprises a linear high molecular polymer and hyperbranched molecules. The topological three-dimensional structure silicon-based negative electrode binder can form an interpenetrating three-dimensional network through in-situ polymerization, provide multidimensional high adhesive force for a silicon negative electrode, effectively inhibit the volume expansion of the silicon negative electrode in the charge-discharge cycle process, and further prolong the cycle life of a lithium ion battery. In addition, the invention also provides a negative plate adopting the topological three-dimensional structure silicon-based negative electrode binder, a preparation method thereof and a battery.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a topological three-dimensional structure silicon-based negative electrode binder, a negative electrode sheet, a preparation method of the negative electrode sheet and a battery.
Background
In recent years, rapid development of various portable electronic devices, electric vehicles and hybrid vehicles has led to an increasing demand for lithium ion batteries with high energy density and long cycle life. At present, graphite is mainly used as a negative electrode material of a commercial lithium ion battery, but the lower theoretical specific capacity (372 mAh/g) of the commercial lithium ion battery limits the further improvement of the electrochemical performance of the commercial lithium ion battery. Silicon becomes one of ideal candidate materials for high energy storage lithium ion batteries with high theoretical specific capacity (4200 mAh/g) and low operating voltage. However, in the lithium intercalation process, silicon is easily subjected to volume change of 300% or more and forms an unstable solid electrolyte interface film (SEI film), thereby causing breakage and pulverization of the silicon structure, and greatly impairing the cycle life and capacity of the battery.
At present, most of researches for solving the problem of silicon expansion are focused on nanocrystallization of silicon particles and compositing with carbon-based materials, and the use of efficient binders is also an effective solution. The conventional binder polyvinylidene fluoride (PVDF) has weak van der waals force with silicon particles, and it is difficult to buffer the volume change of silicon during charge and discharge. In recent years, methylcellulose (CMC), polyacrylic acid (PAA), alginic acid (SA) have been used as base material binders to improve cycle performance. The molecules of the polymer contain a large number of polar functional groups, can form hydrogen bonds with the silicon surface oxide layer, enhance the interaction force between the binder and the silicon material, and improve the structural stability of the electrode. However, the adhesive has a linear structure, and the regular molecular structure makes the polyacrylic acid adhesive relatively brittle and has poor mechanical properties, and irreversible sliding occurs on the surface of the electrode material after repeated charge and discharge cycles, which is shown as the behavior that obvious cracks and the like are easy to appear after the corresponding electrode plate is cycled, which is unfavorable for the exertion of the electrochemical properties of the electrode.
Disclosure of Invention
The invention provides a topological three-dimensional structure silicon-based anode binder, an anode sheet, a preparation method thereof and a battery, and aims to solve the technical problem that the existing anode material linear polymer binder is poor in mechanical property. The interpenetrating three-dimensional network is formed by in-situ polymerization, so that multidimensional high adhesive force is provided for the silicon negative electrode, the volume expansion of the silicon negative electrode in the charge-discharge cyclic process is effectively inhibited, and the cycle life of the lithium ion battery is further prolonged.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the invention provides a topological three-dimensional structure silicon-based negative electrode binder, which comprises a linear high molecular polymer and hyperbranched molecules.
Further, the linear high molecular polymer is at least one of polyacrylic acid, sodium carboxymethyl cellulose, alginic acid, chitosan, polyvinyl alcohol, heparin, starch and guar gum.
Further, the hyperbranched molecule is at least one of polydopamine, hydroxylated cyclodextrin, cyclodextrin polymer, tannic acid polymer and phytic acid.
Further, the number average molecular weight of the linear high molecular polymer is more than or equal to 10 ten thousand.
Further, the mass concentration of the solution formed by adding the linear high molecular polymer and the branched molecule into the solvent is 1-20wt%.
Further, the linear high molecular polymer: the mass ratio of the hyperbranched molecules is 1:0.02-0.5.
Further, the in-situ polymerization temperature of the binder is 30-100 ℃ and the time is 1-3 hours.
In a second aspect, the invention provides a negative electrode sheet, which comprises a current collector and a negative electrode material, wherein the raw materials of the negative electrode material comprise, by weight, 7-9 parts of nano silicon active substances, 1-2 parts of conductive agents and 1-2 parts of binders, and the binders are the binders according to any one of the above.
In a third aspect, the present invention provides a method for preparing the negative electrode sheet as described above, comprising the steps of: uniformly mixing a silicon active substance, a conductive agent and a binder, coating the mixture on the surface of a current collector, and rolling and slitting after drying to obtain a silicon negative plate of the lithium ion battery;
the drying temperature of the lithium ion battery silicon negative plate is 110-130 ℃, and the drying time is 8-15 h.
In a fourth aspect, the present invention provides a lithium ion battery comprising a battery as described above
Is a silicon negative electrode plate of a lithium ion battery.
In summary, the beneficial effects of the invention are as follows:
the invention relates to a topological three-dimensional structure silicon-based negative electrode binder, a negative electrode sheet, a preparation method thereof and a battery. The linear high molecular polymer and the branched molecule respectively have different functional groups (such as-OH, -COOH, -NH) 2 Etc.), and a three-dimensional network structure is formed through esterification and condensation, so as to form multidimensional hydrogen bond acting force. The adhesive is modified into a surface adhesive by a dot-shaped or linear adhesive, and a compact protective film is formed on the surface of the silicon material. The composite binder can provide enough mechanical support and strain resistance for silicon volume expansion, effectively inhibit irreversible lithium consumption of the electrode, and is beneficial to improving the first coulombic efficiency and the cycle life of the anode material.
The topological three-dimensional structure silicon-based negative electrode binder, the negative electrode sheet and the preparation method and the battery thereof have the advantages that firstly, the preparation process of the three-dimensional structure binder is simple, the operation is convenient, the cost is lower, and the mass production can be realized; secondly, hydroxyl, carboxyl and esterification groups are introduced into the composite binder, so that stronger hydrogen bonds can be formed with a silicon oxide thin layer on the surface of silicon, and the hydrogen bonds are tightly combined with silicon nanoparticles to form a current collector, so that the volume expansion of silicon can be effectively weakened, and meanwhile, the electrochemical performance of nano silicon is improved; finally, the linear high polymer and hyperbranched molecules are polymerized in situ to form a three-dimensional grid structure by the composite adhesive, so that multidimensional hydrogen bond acting force is formed, linear polyacrylic acid is modified into a surface adhesive by the dot-shaped or linear adhesive, a compact protective film is formed on the surface of a silicon material, irreversible sliding of the linear adhesive can be effectively inhibited, and the multidimensional hydrogen bond acting force between the linear adhesive and a silicon cathode can improve first coulomb efficiency, reversible capacity and cycling stability of the effective electrode material.
Drawings
FIG. 1 is a plan view of the long-cycle rear pole piece of the silicon negative electrode obtained in the composite binder example 1 and comparative example 4 of the present invention;
FIG. 2 is a cross-sectional view of the long-cycle rear pole piece of the silicon negative electrode obtained in the composite binder example 1 and comparative example 4 of the present invention;
FIG. 3 is a graph comparing the cycle stability of the silicon negative electrodes obtained in the composite binder example 1 of the present invention with that of the comparative example 4;
fig. 4 is a graph comparing electrochemical impedance spectra after long cycles of the resultant silicon anode of the composite binder example 1 of the present invention and comparative example 4.
Description of the embodiments
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1-4, in a first aspect, the present invention provides a topological three-dimensional structure silicon-based anode binder, which comprises a linear high molecular polymer and hyperbranched molecules.
Wherein the linear high molecular polymer is at least one of polyacrylic acid, sodium carboxymethyl cellulose, alginic acid, chitosan, polyvinyl alcohol, heparin, starch and guar gum.
Wherein the hyperbranched molecule is at least one of polydopamine, hydroxylated cyclodextrin, cyclodextrin polymer, tannic acid polymer and phytic acid.
Wherein the number average molecular weight of the linear high molecular polymer is more than or equal to 10 ten thousand.
Wherein the mass concentration of the solution formed by adding the linear high molecular polymer and the branched molecule into the solvent is 1-20wt%.
Wherein the linear high molecular polymer: the mass ratio of the hyperbranched molecules is 1:0.02-0.5.
Wherein the in-situ polymerization temperature of the binder is 30-100 ℃ and the time is 1-3 h.
In a second aspect, the invention provides a negative electrode sheet, which comprises a current collector and a negative electrode material, wherein the raw materials of the negative electrode material comprise, by weight, 7-9 parts of nano silicon active substances, 1-2 parts of conductive agents and 1-2 parts of binders, and the binders are the binders according to any one of the above.
In a third aspect, the present invention provides a method for preparing the negative electrode sheet, including the following steps: and uniformly mixing the silicon active substance, the conductive agent and the adhesive, coating the mixture on the surface of a current collector, and rolling and slitting the mixture after drying to obtain the silicon negative plate of the lithium ion battery.
The drying temperature of the lithium ion battery silicon negative plate is 110-130 ℃, and the drying time is 8-15 h.
Preferably, the drying temperature of the lithium ion battery silicon negative plate is 120 ℃, and the drying time is 12 hours.
In a fourth aspect, the invention provides a lithium ion battery, which comprises the silicon negative electrode plate of the lithium ion battery.
Examples
The preparation method of the composite binder for the silicon anode material in the embodiment is as follows:
respectively preparing aqueous solution with mass fraction of 10wt% from linear high molecular polymer polyacrylic acid (molecular weight 45 w) and hyperbranched molecular beta-cyclodextrin polymer under water bath heating condition;
the dissolution temperature of the polyacrylic acid and the beta-cyclodextrin polymer is 60-100 ℃.
Mixing polyacrylic acid and beta-cyclodextrin polymer in a mass ratio of 9:1, and mixing for 1-3 hours at a stirring speed of 100-500 rpm in a water bath at 60 ℃ to perform partial esterification reaction. And obtaining the special binder for the silicon anode material.
The silicon negative electrode sheet is prepared by the following method: nano silicon active material: conductive carbon black: the adhesive glue solution is uniformly mixed according to the mass ratio of 8:1:1, and the slurry is prepared in a planetary ball mill at the rotating speed of 200 rpm; the slurry is evenly scraped on copper foil, the current collector coated with the electrode slurry is placed in vacuum at 120 ℃ for drying 12h, then the slurry coated on the current collector is rolled and punched, and the CR2025 button cell is assembled in a glove box.
And on a blue-ray testing system, the charge-discharge voltage range is 0.001~2.0 V,0.2C multiplying power, and the charge-discharge test is carried out under the normal temperature condition.
Examples
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the hyperbranched molecule is selected from dopamine polymer.
The preparation method of the dopamine polymer solution comprises the following steps: 0.2 Dissolving the dopamine g in 10 g deionized water, and regulating the pH value of the system to 8-10 by utilizing lithium hydroxide; and magnetically stirring 12-h at normal temperature, and preparing uniform 2wt% dopamine polymer aqueous solution without agglomeration and flocculation.
Mixing polyacrylic acid and beta-cyclodextrin polymer in a mass ratio of 9:1, and mixing for 1-3 hours at a stirring speed of 100-500 rpm in a water bath at 60 ℃ to perform partial esterification reaction. And obtaining the special binder for the silicon anode material.
Examples
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the hyperbranched molecule is selected from tannic acid self-polymer.
The preparation method of the tannic acid self-polymer solution comprises the following steps: 0.2 Dissolving the tannic acid in 10 g deionized water, and regulating the pH value of the system to 8-10 by utilizing lithium hydroxide; magnetic stirring is carried out at normal temperature for 6 h, no agglomeration and flocculation phenomena are caused, and the uniform 2wt% tannic acid self-polymer aqueous solution is prepared.
Mixing polyacrylic acid and tannic acid self-polymers in a mass ratio of 9:1, and mixing for 1-3 hours at a stirring speed of 100-500 rpm in a water bath at 60 ℃ to perform partial esterification reaction. And obtaining the special binder for the silicon anode material.
Examples
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the linear high polymer is sodium carboxymethyl cellulose and is prepared into a solution with the mass fraction of 2wt percent.
Examples
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the linear high polymer is sodium alginate and is prepared into a solution with the mass fraction of 10 wt%.
Examples
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the linear high polymer is chitosan and is prepared into a solution with the mass fraction of 2 wt%.
Comparative example 1
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the polyacrylic acid and the cyclodextrin polymer are mixed according to the mass ratio of 8:2.
Comparative example 2
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: the super branched chain molecule is beta-cyclodextrin monomer.
Comparative example 3
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: polyacrylic acid alone was used as the binder.
Comparative example 4
This example provides a silicon negative electrode binder, and a method for preparing an electrode thereof, which is substantially the same as example 1 except that: only sodium carboxymethyl cellulose is used as a binder.
Table 1: composition of the binders of examples and comparative examples
| First component | Second component | Proportion of | |
| Example 1 | Polyacrylic acid | Beta-cyclodextrin polymers | 9：1 |
| Example 2 | Polyacrylic acid | Dopamine polymers | 9：1 |
| Example 3 | Polyacrylic acid | Tannic acid polymer | 9：1 |
| Example 4 | Sodium carboxymethyl cellulose | Beta-cyclodextrin polymers | 9：1 |
| Example 5 | Sodium alginate | Beta-cyclodextrin polymers | 9：1 |
| Example 6 | Chitosan | Beta-cyclodextrin polymers | 9：1 |
| Comparative example 1 | Polyacrylic acid | Beta-cyclodextrin polymers | 8：2 |
| Comparative example 2 | Polyacrylic acid | Beta-cyclodextrin | 9：1 |
| Comparative example 3 | Polyacrylic acid | 1：0 | |
| Comparative example 4 | Sodium carboxymethyl cellulose | 1：0 |
The electrochemical performance test of the assembled battery using the electrodes obtained in examples 1 to 6 and comparative examples 1 to 4 as a negative electrode and lithium metal as a counter electrode is shown in table 2.
| Specific capacity for initial charge (mAh/g) | First coulombic efficiency (%) | 0.2 Capacity retention rate of 200 weeks for C cycle | Expansion ratio of full charge sheet (%) | |
| Example 1 | 3357 | 90.2 | 75.3 | 10 |
| Example 2 | 3316 | 87.3 | 72.7 | 13 |
| Example 3 | 3245 | 89.5 | 72.9 | 12 |
| Example 4 | 3335 | 81.5 | 65.7 | 18 |
| Example 5 | 3226 | 84.9 | 67.3 | 15 |
| Example 6 | 3341 | 82.8 | 59 | 16 |
| Control group 1 | 3251 | 85.3 | 61.6 | 14 |
| Control group 2 | 3329 | 83.4 | 61.7 | 16 |
| Control group 3 | 3114 | 82.4 | 44.9 | 18 |
| Control group 4 | 3136 | 75.8 | 27.2 | 22 |
The invention relates to a topological three-dimensional structure silicon-based negative electrode binder, a negative electrode sheet, a preparation method thereof and a battery. The linear high molecular polymer and the branched molecule respectively have different functional groups (such as-OH, -COOH, -NH) 2 Etc.), and a three-dimensional network structure is formed through esterification and condensation, so as to form multidimensional hydrogen bond acting force. The adhesive is modified into a surface adhesive by a dot-shaped or linear adhesive, and a compact protective film is formed on the surface of the silicon material. The composite binder may be silicon volumeThe expansion provides sufficient mechanical support and strain resistance, effectively inhibits irreversible lithium consumption of the electrode, and is beneficial to improving the first coulombic efficiency and cycle life of the anode material.
The topological three-dimensional structure silicon-based negative electrode binder, the negative electrode sheet and the preparation method and the battery thereof have the advantages that firstly, the preparation process of the three-dimensional structure binder is simple, the operation is convenient, the cost is lower, and the mass production can be realized; secondly, hydroxyl, carboxyl and esterification groups are introduced into the composite binder, so that stronger hydrogen bonds can be formed with a silicon oxide thin layer on the surface of silicon, and the hydrogen bonds are tightly combined with silicon nanoparticles to form a current collector, so that the volume expansion of silicon can be effectively weakened, and meanwhile, the electrochemical performance of nano silicon is improved; finally, the linear high polymer and hyperbranched molecules are polymerized in situ to form a three-dimensional grid structure by the composite adhesive, so that multidimensional hydrogen bond acting force is formed, linear polyacrylic acid is modified into a surface adhesive by the dot-shaped or linear adhesive, a compact protective film is formed on the surface of a silicon material, irreversible sliding of the linear adhesive can be effectively inhibited, and the multidimensional hydrogen bond acting force between the linear adhesive and a silicon cathode can improve first coulomb efficiency, reversible capacity and cycling stability of the effective electrode material.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.
Claims (10)
1. A topological three-dimensional structure silicon-based negative electrode binder is characterized in that: including linear high molecular polymers and hyperbranched molecules.
2. The topological three-dimensional structure silicon-based anode binder according to claim 1, wherein: the linear high molecular polymer is at least one of polyacrylic acid, sodium carboxymethyl cellulose, alginic acid, chitosan, polyvinyl alcohol, heparin, starch and guar gum.
3. The topological three-dimensional structure silicon-based anode binder according to claim 1, wherein: the hyperbranched molecule is at least one of polydopamine, hydroxylated cyclodextrin, cyclodextrin polymer, tannic acid polymer and phytic acid.
4. The topological three-dimensional structure silicon-based anode binder according to claim 1, wherein: the number average molecular weight of the linear high molecular polymer is more than or equal to 10 ten thousand.
5. The topological three-dimensional structure silicon-based anode binder according to claim 1, wherein: the mass concentration of the solution formed by adding the linear high molecular polymer and the branched molecule into the solvent is 1-20wt%.
6. The topological three-dimensional structure silicon-based anode binder according to claim 1, wherein: the linear high molecular polymer: the mass ratio of the hyperbranched molecules is 1:0.02-0.5.
7. The topological three-dimensional structure silicon-based anode binder according to claim 1, wherein: the in-situ polymerization temperature of the binder is 30-100 ℃ and the time is 1-3 h.
8. A negative electrode sheet, characterized in that: the negative electrode material comprises 7-9 parts by weight of nano silicon active substance, 1-2 parts by weight of conductive agent and 1-2 parts by weight of binder, wherein the binder is the binder as claimed in any one of claims 1-7.
9. A method for producing the negative electrode sheet according to claim 8, characterized in that: the method comprises the following steps: uniformly mixing a silicon active substance, a conductive agent and a binder, coating the mixture on the surface of a current collector, and rolling and slitting after drying to obtain a silicon negative plate of the lithium ion battery;
the drying temperature of the lithium ion battery silicon negative plate is 110-130 ℃, and the drying time is 8-15 h.
10. A lithium ion battery, characterized in that: the lithium ion battery comprises the lithium ion battery silicon negative electrode plate of claim 8.
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