3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds, negative electrode plate and battery
By preparing a 3D network silicon-carbon composite anode binder based on hydrogen bonds, the battery capacity loss caused by volume expansion in lithium-ion batteries is solved, and the stability and cycling performance of the battery are improved.
Patent Information
- Application Number
- CN202510687676.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-27
- Publication Date
- 2025-08-29
AI Technical Summary
The existing silicon-carbon composite anode material has large internal stress caused by volume expansion in lithium-ion batteries, powdered active substances, and the commonly used binder PVDF cannot effectively buffer deformation, resulting in serious battery capacity loss.
Multivariate polymers were prepared by a two-step reaction method containing ether-based flexible molecular chains and self-polymerization characteristics, forming a 3D network structure based on hydrogen bonds, enhancing the adhesion between the binder and the electrode components, and building a stable solid electrolyte interface film (SEI film).
The electrochemical performance and mechanical stability of the silicon-carbon composite negative electrode are improved, and the cycle performance and mechanical properties of the electrode plate are significantly improved.
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Figure BDA0005421020950000071
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of batteries, and in particular to a 3D network silicon-carbon composite negative electrode binder, a negative electrode sheet and a battery constructed based on hydrogen bonds. Background Art
[0002] The silicon-carbon composite anode material currently in widespread use has a specific capacity of 4200 mAh g when fully lithiated. -1 However, its volume expansion coefficient is as high as 400%, which makes the internal stress of the battery greater during charge and discharge, causing the active material to pulverize and form a new SEI film on the exposed silicon surface, resulting in greater impedance and lower utilization of active materials, resulting in serious loss of battery capacity. The calculated specific capacity of widely used graphite negative electrode materials is only 372mAh·g -1 , the low capacity hinders its application in high-capacity fast charge and discharge batteries.
[0003] To solve the above problems, commonly used Si negative electrode materials and graphite negative electrode materials can be used together to prepare silicon-carbon composite negative electrode materials for lithium-ion batteries. This can not only alleviate the low capacity problem of graphite materials, but also alleviate the large capacity loss problem of silicon-carbon composite negative electrode materials due to volume effect.
[0004] However, the binder polyvinylidene fluoride (PVDF) currently used in commercial applications is based on weak van der Waals interactions formed by F atoms, which is insufficient to buffer the expansion and contraction deformation of the active material during battery operation. After multiple cycles, batteries containing silicon-carbon composite negative electrode materials mixed with Si and graphite will have cracks on the electrode surface, increasing the distance between the active materials and causing them to fall off the current collector. In addition, PVDF easily reacts with lithiated alloys, which will greatly consume the active material, causing a significant attenuation of the battery capacity and failing to stabilize the silicon-carbon negative electrode. Summary of the Invention
[0005] The purpose of the present invention is to provide a 3D network silicon-carbon composite negative electrode binder, a negative electrode sheet and a battery constructed based on hydrogen bonds to solve the above problems.
[0006] To achieve the above object, the technical solution provided by the present invention is:
[0007] The first aspect of the present application provides a method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding, comprising the following steps:
[0008] A multi-polymer containing polar groups is prepared by selecting a natural polymer with a flexible molecular chain containing ether groups and a monomer with self-polymerization characteristics;
[0009] dissolving the prepared multipolymer and PVDF in a first solvent to prepare a negative electrode binder precursor solution;
[0010] A natural polymer with polar groups is mixed with a negative electrode binder precursor solution to prepare a silicon-carbon composite negative electrode binder.
[0011] To optimize the above technical solutions, specific limitations also include:
[0012] The flexible molecular chain natural polymer containing ether groups is selected from bismorpholine diethyl ether or polyglycerol ether; the monomer with self-polymerization properties includes 2,2-dihydroxymethylpropionic acid, isophorone diisocyanate and dopamine hydrochloride; the natural polymer with polar groups is konjac glucomannan; and the polar groups are selected from at least one of -OH and -COOH.
[0013] The flexible molecular chain natural polymer containing ether groups and the monomer with self-polymerization characteristics are reacted in two steps to prepare a multi-polymer:
[0014] S1: dissolving 2,2-dimethylolpropionic acid and isophorone diisocyanate in a second solvent, heating to 65-75° C. and reacting at this temperature for 8-15 minutes, then adding a natural polymer with a flexible molecular chain containing an ether group and reacting for 3-5 hours to obtain a first reactant;
[0015] S2: Sodium bicarbonate and anhydrous sodium tetraborate are dissolved in a third solvent, and then dopamine hydrochloride is added and stirred to obtain a second reactant. The first reactant and the second reactant are mixed and stirred in the dark to obtain a product. The reaction process is carried out in an inert gas atmosphere.
[0016] The pH of the product is adjusted to acidic to obtain a multipolymer.
[0017] The first solvent is selected from N, N-methylpyrrolidone and water; the second solvent is selected from butanone and methyl ethyl ketone; the third solvent is selected from N, N-methylpyrrolidone and dihydro-L-glucoside
[0018] In step S1, the mass / volume ratio of 2,2-dihydroxymethylpropionic acid, isophorone diisocyanate, ether-containing flexible molecular chain natural polymer, and the second solvent is 1.5-2.2:6-7:0.5-0.7:45-55 g / g / g / ml; in step S2, the mass ratio of sodium bicarbonate, anhydrous tetraboric acid, sodium dopamine hydrochloride, and the third solvent is 1-2:3-4:5-6:15-25; the mass ratio of 2,2-dihydroxymethylpropionic acid and sodium dopamine hydrochloride is 1.5-2.2:5-7.
[0019] Furthermore, the obtained multipolymer and PVDF are co-dissolved in a first solvent to prepare a negative electrode binder precursor solution, specifically:
[0020] Dissolving a multipolymer and PVDF in a first solvent to obtain a multipolymer solution and a PVDF solution respectively; mixing the multipolymer solution and the PVDF solution and stirring at room temperature for 2.5 to 4 hours to obtain a negative electrode binder precursor solution;
[0021] The mass fractions of the multipolymer solution and the PVDF solution are 18-25% and 18-25% respectively; the mixing volume ratio of the multipolymer solution and the PVDF solution is 0.8-1:0.8-1 respectively.
[0022] Furthermore, the natural polymer and the negative electrode binder precursor solution are mixed to prepare a silicon-carbon composite negative electrode binder, and the mixing conditions are as follows: the natural polymer and the negative electrode binder precursor solution are diluted with water added with Tris-HCl buffer respectively, and the dilutions of the two are mixed and stirred at room temperature for 50 to 70 minutes, and the mass ratio of the natural polymer to the negative electrode binder precursor solution and the total amount of dilution water is 2 to 3:2 to 3;16 to 24.
[0023] The second aspect of the present application provides a 3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds, which is prepared using the above-mentioned method.
[0024] The third aspect of the present application provides a negative electrode sheet comprising the above-mentioned 3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds.
[0025] A fourth aspect of the present application provides a battery comprising the above-mentioned negative electrode sheet.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] The present invention selects a natural polymer with a flexible molecular chain containing ether groups and a monomer with self-polymerization properties to prepare a multipolymer containing polar groups through a two-step reaction method. A large number of dynamic reversible hydrogen bonds are formed between the multipolymer molecules prepared by the two-step reaction and the various components of the electrode and between the binder's own structure to form a 3D network, thereby enhancing the adhesion between the polymer and other components of the electrode and improving the electrochemical performance of the silicon negative electrode.
[0028] The present invention combines a natural polymer with polar groups with a negative electrode binder precursor solution made from a multi-polymer to prepare a silicon-carbon composite negative electrode binder. The synergistic effect of the natural polymer enhances the elasticity and adhesion of the three-dimensional network structure. The polar groups also significantly promote the construction of a 3D network with reversible hydrogen bonds, contributing to the generation of reversible restoring forces during battery charge and discharge cycles. The polymer also provides multiple action sites, effectively inhibiting the mechanical behavior between the active material, conductive particles, and current collector, thereby forming a stable solid electrolyte interface film (SEI film) to maintain electrode stability and improve the cycling performance of the silicon negative electrode.
[0029] The binder of the present invention is used for silicon-carbon composite negative electrode batteries containing Si and graphite, and can significantly improve the mechanical properties of the pole pieces and the electrochemical properties of the batteries. DETAILED DESCRIPTION
[0030] The above contents of the present invention are further described in detail below in the form of specific implementation methods, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments. All technologies implemented based on the above contents of the present invention belong to the scope of the present invention.
[0031] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the reagents, methods and equipment used are conventional reagents, methods and equipment in the art unless otherwise specified.
[0032] For the sake of simplicity, this document only specifically discloses some numerical values and optional ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range. Similarly, any upper limit can be combined with any other upper limit to form an unspecified range; the optional items in the optional range can also be combined arbitrarily.
[0033] The present invention provides a method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding, comprising the following steps:
[0034] A multi-polymer containing polar groups is prepared by selecting a natural polymer with a flexible molecular chain containing ether groups and a monomer with self-polymerization characteristics;
[0035] dissolving the prepared multipolymer and PVDF in a first solvent to prepare a negative electrode binder precursor solution;
[0036] A natural polymer with polar groups is mixed with a negative electrode binder precursor solution to prepare a silicon-carbon composite negative electrode binder.
[0037] The present invention selects a natural polymer with a flexible molecular chain containing ether groups and a monomer with self-polymerization properties to prepare a multipolymer through a two-step reaction method. A large number of dynamic reversible hydrogen bonds are formed between the multipolymer molecules prepared by the two-step reaction and the various components of the electrode and between the binder's own structure to form a 3D network, thereby enhancing the adhesion between the polymer and other components of the electrode and improving the electrochemical performance of the silicon negative electrode.
[0038] The present invention then prepares a silicon-carbon composite anode binder by combining a natural polymer with a polar group and a negative electrode binder precursor solution made from a multi-polymer. The synergistic effect of the natural polymers can enhance the elasticity and adhesion of the three-dimensional network structure, promoting the construction of a 3D network with reversible hydrogen bonds. This helps generate reversible restoring forces during battery charge and discharge cycles, while providing multiple action sites that effectively inhibit the mechanical behavior between the active material, conductive particles, and current collector, thereby forming a stable solid electrolyte interface film (SEI film) to maintain electrode stability and improve the cycling performance of the silicon anode.
[0039] In some embodiments, the flexible molecular chain natural polymer containing an ether group is selected from bismorpholine diethyl ether or polyglycerol ether.
[0040] In some embodiments, the natural polymer with polar groups is konjac glucomannan (KGM). KGM is a natural polymer with polar groups. It is a high-molecular-weight polysaccharide composed of mannose and glucose linked by β-1,4 glycosidic bonds in a 1.6:1 ratio. Due to the high hydroxyl content in the molecular chain, KGM has strong adhesion and excellent mechanical properties. Considering the inherent superior properties of KGM, its addition can enhance the elasticity and adhesion of the three-dimensional network structure. At the same time, it also contains polar groups, which will greatly promote the construction of a 3D network formed by reversible hydrogen bonds.
[0041] The polar group in the present invention refers to at least one of -OH and -COOH.
[0042] In some embodiments, the monomer having self-polymerization properties includes three monomers: 2,2-dimethylolpropionic acid, isophorone diisocyanate, and dopamine hydrochloride; the flexible molecular chain natural polymer containing an ether group and the monomer having self-polymerization properties are reacted in a two-step process to prepare a multipolymer:
[0043] S1: dissolving 2,2-dimethylolpropionic acid and isophorone diisocyanate in a second solvent, heating to 65-75° C. and reacting at this temperature for 8-15 minutes, then adding a natural polymer with a flexible molecular chain containing an ether group and reacting for 3-5 hours to obtain a first reactant;
[0044] S2: Sodium bicarbonate and anhydrous sodium tetraborate are dissolved in a third solvent, and then dopamine hydrochloride is added and stirred to obtain a second reactant. The first reactant and the second reactant are mixed and stirred in the dark to obtain a product. The reaction process is carried out in an inert gas protective atmosphere; the pH of the product is adjusted to acidic to obtain a multipolymer.
[0045] In some embodiments, the first solvent is selected from N,N-methylpyrrolidone and water; the second solvent is selected from butanone and methyl ethyl ketone; and the third solvent is selected from N,N-methylpyrrolidone and dihydro-L-glucoside.
[0046] In step S1, the mass / volume ratio of 2,2-dihydroxymethylpropionic acid, isophorone diisocyanate, ether-containing flexible molecular chain natural polymer, and the second solvent is 1.5-2.2:6-7:0.5-0.7:45-55 g / g / g / ml; in step S2, the mass ratio of sodium bicarbonate, anhydrous tetraboric acid, sodium dopamine hydrochloride, and the third solvent is 1-2:3-4:5-6:15-25; the mass ratio of 2,2-dihydroxymethylpropionic acid and sodium dopamine hydrochloride is 1.5-2.2:5-7.
[0047] In some embodiments, the obtained multipolymer and PVDF are co-dissolved in a first solvent to prepare a negative electrode binder precursor solution, specifically:
[0048] Dissolving a multipolymer and PVDF in a first solvent to obtain a multipolymer solution and a PVDF solution respectively; mixing the multipolymer solution and the PVDF solution and stirring at room temperature for 2.5 to 4 hours to obtain a negative electrode binder precursor solution;
[0049] The mass fractions of the multipolymer solution and the PVDF solution are 18-25% and 18-25% respectively; the mixing volume ratio of the multipolymer solution and the PVDF solution is 0.8-1:0.8-1 respectively.
[0050] In some embodiments, a natural polymer is mixed with a negative electrode binder precursor solution to prepare a silicon-carbon composite negative electrode binder. The mixing conditions are as follows: the natural polymer and the negative electrode binder precursor solution are diluted with water added with Tris-HCl buffer respectively, and the dilutions of the two are mixed and stirred at room temperature for 50 to 70 minutes. The mass ratio of the natural polymer to the negative electrode binder precursor solution and the total amount of dilution water is 2 to 3: 2 to 3; 16 to 24.
[0051] The present invention also provides a 3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds, which is prepared using the above method.
[0052] The present invention also provides a negative electrode sheet comprising the above-mentioned 3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds.
[0053] The present invention also provides a battery comprising the above-mentioned negative electrode sheet.
[0054] The technical solution of the present invention is further described in detail below with reference to specific embodiments:
[0055] Description of materials involved in the examples:
[0056] Konjac glucomannan (KGM), viscosity ≥15000 mPa.s; dopamine hydrochloride (DOP), purity: 98%; 2,2-dihydroxymethylpropionic acid (DMPA), chemically pure; isophorone diisocyanate (IPDI), chemically pure; Company: MacLean Reagent Co., Ltd.
[0057] N,N-methylpyrrolidone (NMP), analytical standard; silica, 50-100 nm; bismorpholine diethyl ether, purity ≥99%; butanone, chemically pure; sodium bicarbonate, chemically pure; anhydrous sodium tetraborate, chemically pure; ethyl acetate, chemically pure; Company: Aladdin Reagent Co., Ltd.
[0058] Polyvinylidene fluoride (PVDF), battery grade; Company: Solvay, USA.
[0059] Acetylene black, battery grade; Company: Alltieva Chemical Company.
[0060] 0.5xΦ16mm lithium metal, battery grade; Company: Shengxin Lithium Energy Group Co., Ltd.
[0061] Specific implementation methods:
[0062] (1) Preparation of ternary polymer IDD: 2g DMPA and 6.63g IPDI were dissolved in 50ml butanone, heated to 70℃ and kept at constant temperature for 10min, then 0.6g bismorpholine diethyl ether (DY-DMDEE) was added dropwise to the reaction flask. After the addition was complete, the reaction was continued for 4h until the reaction solution was clear and transparent. 1.5g sodium bicarbonate and 3.5g anhydrous sodium tetraborate were dissolved in 20g NMP and mechanically stirred for 0.5h, then 5.7g dopamine hydrochloride was added and stirred in an argon atmosphere for 0.5h. The prepared clear and transparent solution was then added to the flask containing DOP to ensure an argon atmosphere, stirred at room temperature overnight, and protected from light throughout the process. The pH of the solution was then adjusted to about 2, precipitated with ethyl acetate, and filtered to obtain the ternary polymer IDD.
[0063] (2) Preparation of precursor binder IP: 5 g of IDD and 5 g of PVDF were dissolved in 20 g of NMP, respectively, and stirred at room temperature for 3 h to prepare 25 g of 20% IDD solution and 25 g of 20% PVDF solution. Then, 5 g of 20% IDD solution and 5 g of 20% PVDF solution were mixed and stirred at room temperature for 3 h, and named IP (wherein the mass ratio of IDD to PVDF was 1:1).
[0064] (3) Preparation of composite binder: 5g KGM, 5g precursor binder IP and a trace amount of Tris-HCl buffer were dissolved in 20g deionized water, respectively, and stirred at room temperature for 30min to prepare 25g of 20% KGM solution and 25g of 20% IP solution. Then, 5g of 20% KGM solution and 7.5g of 20% IP solution, 5g of 20% KGM solution and 5g of 20% IP solution, and 7.5g of 20% KGM solution and 25g of 20% IP solution were respectively taken. 5g of 20% IP solution were mixed and stirred at room temperature for 60min, and were named KIP-2-3 (Example 1), KIP-1-1 (Example 2) and KIP-3-2 (Example 3), respectively, wherein the mass ratios of KGM and precursor binder IP were 2:3, 1:1, and 3:2, respectively. KIP-1-3 (Comparative Example 3) and KIP-3-1 (Comparative Example 4) prepared by the corresponding method had the mass ratios of KGM and precursor binder IP of 1:3 and 3:1, respectively.
[0065] In addition, 5g PVDF was dissolved in 45g NMP to prepare a 10% binder as a negative electrode binder (Comparative Example 1), and 5g precursor binder IP was added with a trace amount of Tris-HCl buffer and dissolved in 20g deionized water as a negative electrode binder (Comparative Example 2) for comparative tests.
[0066] (4) Preparation of batteries: Using NMP as solvent, silicon and graphite (silicon: graphite is 2:3), binder and conductive additive SuperP are added to a ball mill at a mass ratio of 8:1:1 and ball milled for 12 hours before coating. The mixture is dried in a vacuum drying oven at 100°C for 10 hours and then prepared into circular electrodes of appropriate size for subsequent assembly of button batteries.
[0067] (5) Battery assembly: Assemble CR2032 button cells, use polypropylene (PP) material for the separator, metallic Li material for the counter electrode, and 1 mol / L LiPF6 solution with a volume ratio of EC+DMC+EMC of 1:1:1 as the electrolyte for subsequent testing.
[0068] (6) Testing:
[0069] Peel test: Cut the prepared electrode sheet (the whole electrode sheet before being made into a circular electrode sheet in step (4)) into a 40*25mm strip, then stick 3M double-sided tape on the back of it, and stick the other side of the double-sided tape on the prepared glass slide. Then stick 3M double-sided tape with a specification of 9*1mm on the surface of the electrode. After turning the tape over, stick one side of the tape on the upper fixture of the microcomputer-controlled electronic universal testing machine, and stick the other end of the glass slide on the lower fixture of the testing machine. The mode is selected as the tension-displacement mode, and then the stretching speed is set to 5mm / min.
[0070] Cycling performance test: The BTS-M6A / 5V battery test cycle channel system of Xinkeda Energy Development Co., Ltd. was used to perform a constant current long cycle test on the battery after it was left to stand for 24 hours. The voltage was set to 0.01-3V and the current density was set to 0.3C.
[0071] Swelling Performance Test: Immerse electrodes of appropriate size, shape, and mass in an equal volume of electrolyte. Weigh and measure the samples at 0, 60, 120, and 180 hours after immersion. Record the weights and photograph the samples. Calculate the swelling rate of each sample at each time using the formula: Swelling Rate = (W1 - W2) / W2 x 100% (W1 is the sample weight before immersion, W2 is the sample weight after immersion).
[0072] Table 1 Test results of embodiments and comparative examples Comparing Examples 1 to 3 with Comparative Example 1, it can be seen that the negative electrode binder prepared in the present application can significantly improve the electrode peeling force, has a significantly smaller swelling rate as shown in the swelling performance test, and has good cycle performance.
[0073] Comparing Examples 1 to 3 with Comparative Example 2, it can be seen that the negative electrode binder prepared using only the negative electrode binder precursor solution has a relatively small electrode sheet peeling force and a relatively average cycle performance.
[0074] Comparing Examples 1 to 3 with Comparative Examples 3 and 4, it can be seen that if the mixing ratio of the natural polymer solution to the negative electrode binder precursor solution is too high or too low, the final product effect will be reduced to a certain extent.
[0075] Taking Example 2 as an example, the possible principles are further analyzed as follows:
[0076] When KIP-1-1 is used as a binder, a uniform conductive network exists between the conductive agent SuperP and SiO2. This uniform conductive network is conducive to the wetting of the electrolyte, thereby improving the conductivity between the solid-liquid interface and facilitating the Li + transfer; on the contrary, when PVDF was used as a binder, the conductive agent SuperP showed severe bulk aggregation, which resulted in the transfer of electrons and Li + The transfer is slow.
[0077] The swelling rate of the binder in the electrolyte determines whether the electrode properties are stable. The samples were completely immersed in the electrolyte, and their swelling rates in the electrolyte were weighed and calculated. After immersion for 180 hours, the absorption rate of PVDF to the electrolyte was 30.65%, and the absorption rate of the precursor binder IP to the electrolyte was 18.36%. Obviously, the absorption rate of the precursor binder IP is lower, and it can exist more stably in the electrolyte. There is no obvious change in the KIP solution after adding KGM, indicating that the sample has already shown a relatively stable state.
[0078] The precursor binder IP contains functional groups such as carboxyl and hydroxyl groups, and its chemical reaction with other components of the electrode is relatively strong. However, after further adding KDM to form a new KPI binder, the three-dimensional network structure of the KPI binder enhances the mechanical adhesion. The large number of polar hydroxyl groups is conducive to maintaining the effective connection between the electrode active material and the conductive agent and current collector, effectively enhancing the deformation resistance of the electrode during operation and maintaining the integrity of the electrode structure.
[0079] The first cycle specific capacity of the anode prepared with the precursor binder IP is higher than that of the PVDF anode. This may be because the interfacial interaction between the functional groups such as hydroxyl and carboxyl in the precursor binder IP and other electrode components is relatively strong, which helps to form a more stable SEI film and improve the initial specific capacity of the battery. The initial lithium insertion specific capacity of the KIP-1-1 anode is 3594 mAh g -1 It is the largest among all electrodes, almost close to the theoretical specific capacity of Si material, with an initial coulombic efficiency of 84%, while the initial coulombic efficiency of PVDF negative electrode is only 54.5%.
[0080] The initial discharge capacity of the negative electrode prepared by PVDF is 1389 mAh g -1 After the pre-cycle, the battery has less than 200mAh g -1 The specific capacity of the IP negative electrode is 1633 mAh g -1 After 20 cycles, there is 250mAh·g -1 The specific capacity of the battery is about 3594 mAh g, indicating that the IP binder can enhance the discharge specific capacity of the battery during cycling and can better stabilize the silicon negative electrode in long-term cycling. After further adding KGM, the appropriate amount of hydroxyl groups on the KIP-1-1 negative electrode can form hydrogen bonds with each other and with the active Si surface, which can maintain the stability of the active Si through hydrogen bonding. The initial specific capacity of the battery reaches 3594 mAh g -1 Close to the theoretical specific capacity of Si (3600mAh g -1 ), and even after 20 cycles, it still maintains a high specific capacity of more than 2000mAh·g-1.
[0081] Therefore, the addition of the ternary polymer IDD mainly affects the swelling rate, while the addition of KMG further significantly improves the peeling force and electrochemical performance.
[0082] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modification, equivalent replacement and improvement made by any technician familiar with the profession to the above embodiment without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding, characterized in that: The following steps are involved: A multi-polymer containing polar groups is prepared by selecting a natural polymer with a flexible molecular chain containing ether groups and a monomer with self-polymerization characteristics; dissolving the prepared multipolymer and PVDF in a first solvent to prepare a negative electrode binder precursor solution; A natural polymer with polar groups is mixed with a negative electrode binder precursor solution to prepare a silicon-carbon composite negative electrode binder.
2. The method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding according to claim 1, characterized in that: The flexible molecular chain natural polymer containing ether groups is selected from bismorpholine diethyl ether or polyglycerol ether; the natural polymer with polar groups is konjac glucomannan; and the polar groups are selected from at least one of -OH and -COOH.
3. The method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding according to claim 2, characterized in that: The monomers with self-polymerization properties include three monomers: 2,2-dimethylol propionic acid, isophorone diisocyanate and dopamine hydrochloride; the flexible molecular chain natural polymer containing ether groups and the monomers with self-polymerization properties are reacted in two steps to prepare a multipolymer: S1: dissolving 2,2-dimethylolpropionic acid and isophorone diisocyanate in a second solvent, heating to 65-75° C. and reacting at this temperature for 8-15 minutes, then adding a natural polymer with a flexible molecular chain containing an ether group and reacting for 3-5 hours to obtain a first reactant; S2: Sodium bicarbonate and anhydrous sodium tetraborate are dissolved in a third solvent, and then dopamine hydrochloride is added and stirred to obtain a second reactant. The first reactant and the second reactant are mixed and stirred in the dark to obtain a product. The reaction process is carried out in an inert gas protective atmosphere; the pH of the product is adjusted to acidic to obtain a multipolymer.
4. The method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding according to claim 3, characterized in that: The first solvent is selected from N, N-methylpyrrolidone and water; the second solvent is selected from butanone and methyl ethyl ketone; and the third solvent is selected from N, N-methylpyrrolidone and dihydro-L-glucoside.
5. The method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding according to claim 3, characterized in that: In step S1, the mass / volume ratio of 2,2-dihydroxymethylpropionic acid, isophorone diisocyanate, ether-containing flexible molecular chain natural polymer, and the second solvent is 1.5-2.2:6-7:0.5-0.7:45-55 g / g / g / ml; in step S2, the mass ratio of sodium bicarbonate, anhydrous tetraboric acid, sodium dopamine hydrochloride, and the third solvent is 1-2:3-4:5-6:15-25; the mass ratio of 2,2-dihydroxymethylpropionic acid and sodium dopamine hydrochloride is 1.5-2.2:5-7.
6. The method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding according to claim 3, characterized in that: The obtained multipolymer and PVDF are co-dissolved in a first solvent to prepare a negative electrode binder precursor solution, specifically: Dissolving a multipolymer and PVDF in a first solvent to obtain a multipolymer solution and a PVDF solution respectively; mixing the multipolymer solution and the PVDF solution and stirring at room temperature for 2.5 to 4 hours to obtain a negative electrode binder precursor solution; The mass fractions of the multipolymer solution and the PVDF solution are 18-25% and 18-25% respectively; the mixing volume ratio of the multipolymer solution and the PVDF solution is 0.8-1:0.8-1 respectively.
7. The method for preparing a 3D network silicon-carbon composite negative electrode binder based on hydrogen bonding according to claim 3, characterized in that: The natural polymer and the negative electrode binder precursor solution are mixed to prepare the silicon-carbon composite negative electrode binder. The mixing conditions are as follows: the natural polymer and the negative electrode binder precursor solution are diluted with water added with Tris-HCl buffer respectively, and the dilutions of the two are mixed and stirred at room temperature for 50 to 70 minutes. The mass ratio of the natural polymer to the negative electrode binder precursor solution and the total amount of dilution water is 2 to 3:2 to 3;16 to 24.
8. A 3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds, characterized by: The method according to any one of claims 1 to 7 is used for preparation.
9. A negative electrode sheet, characterized in that: The invention comprises the 3D network silicon-carbon composite negative electrode binder constructed based on hydrogen bonds as described in claim 8.
10. A battery, characterized in that: The negative electrode sheet according to claim 9 is included.