Binder, negative electrode slurry, silicon negative electrode, and sulfide all-solid-state battery

Abstract

The application discloses a kind of binder, negative electrode slurry, silicon negative electrode and sulfide full solid battery, belong to full solid battery field.The negative electrode is by current collector and surface coating negative electrode slurry, slurry includes negative electrode active material and binder.Negative electrode active material is the composite of conductive polymer coated silicon, and the hydrogen bond is formed by the monomer of conductive polymer with silicon surface hydroxyl, in-situ polymerization is realized on the surface of silicon particle, realizes uniform coating, significantly improves the electronic conductivity of silicon negative electrode.Binder uses the triblock copolymer of acrylic acid, 4-styrene sulfonic acid lithium and poly (ethylene glycol) methyl ether methacrylate, and ether bond and lithium sulfonate segment can form single ion conductor, improve the problem that silicon negative electrode is low and lithium ion diffusion is uneven, relieve stress concentration and structural damage, enhance structural stability.The design constructs efficient ion / electron transmission channel in silicon negative electrode, and gives consideration to conductivity and structural stability, can significantly improve the long-term cycle stability of battery.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state battery technology and relates to a binder, negative electrode slurry, silicon negative electrode, and sulfide all-solid-state battery. Background Technology

[0002] With the rise of electric vehicles and increased environmental awareness, higher demands are being placed on energy storage, especially on lithium-ion batteries, particularly regarding their safety performance, energy density, and power density. However, current liquid lithium-ion battery systems are nearing their theoretical energy density limits, and the use of organic electrolytes poses safety hazards such as fire and explosion, making them unsuitable for current needs. Therefore, new battery systems need to be developed to keep pace with the development of the energy storage field.

[0003] All-solid-state batteries, by replacing organic electrolytes with solid-state electrolytes, offer superior safety, higher energy density, and higher power density, making them a hot research topic in the energy storage field. Compared to oxide solid-state electrolytes and composite solid-state electrolytes, sulfide solid-state electrolytes, due to their high ionic conductivity and excellent mechanical properties, have become one of the key research areas in all-solid-state battery development.

[0004] Silicon anodes are favored due to their high theoretical specific capacity (3579 mAh / g) and moderate lithium intercalation potential (~0.4V vs. Li). + Lithium (Li₂) suppresses lithium dendrite growth and, as the second most abundant element on Earth, is low-cost and widely available. Therefore, it holds great promise for achieving high energy and power density in sulfide-based all-solid-state batteries. However, the large volume change (~300%) during lithium insertion / extraction in silicon generates significant internal stress, causing vertical cracks within the silicon anode. This increases the curvature of the lithium-ion transport path and the battery's internal resistance, ultimately leading to battery failure. Furthermore, silicon's low conductivity and ion diffusion coefficient make it difficult for silicon anodes to achieve their full capacity at high current densities. These two issues hinder the application of silicon anodes in sulfide-based all-solid-state batteries. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a binder, anode slurry, silicon anode, and sulfide all-solid-state battery to solve the problem that the low conductivity and ion diffusion coefficient of silicon anode in the prior art make it difficult for the anode to achieve its capacity at a large current density.

[0006] To achieve the above objectives, the present invention employs the following technical solution: An adhesive, said adhesive being a block copolymer of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate.

[0007] A further improvement of the present invention is that: Preferably, the block copolymer has any one of the following three structural formulas:

[0008]

[0009] Where x ranges from 30 to 50, y ranges from 10 to 20, z ranges from 30 to 60, and n ranges from 10 to 30.

[0010] A negative electrode slurry includes a silicon negative electrode active material, a binder, and a solvent; the silicon negative electrode active material is a material in which conductive polymers coat silicon particles; the binder is the aforementioned binder, and the conductive polymer is pyrrole, aniline, or 3,4-dimethylformamide. Any one or more of ethylenedioxythiophene.

[0011] Preferably, the silicon particles are nano-silicon or micron-silicon, and the particle size range of the silicon particles is 30 nm-1 μm.

[0012] Preferably, the mass ratio of the silicon particles to the conductive polymer monomer is (1.2~2.4):1.

[0013] A method for preparing the above-mentioned negative electrode slurry includes the following steps: mixing a conductive polymer-coated silicon negative electrode active material with a copolymer binder in a solvent to obtain a mixture, and ball milling the mixture to obtain a uniform negative electrode slurry; The method for preparing the negative electrode active material is as follows: a conductive polymer monomer is dispersed in an acidic solvent to obtain a monomer solution; silicon particles are added to the monomer solution, mixed evenly, and an oxidant is added to generate a mixture; the mixture after reaction is filtered, washed, and dried to obtain a negative electrode active material with conductive polymer coated silicon. The copolymer adhesive is prepared by dissolving acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate monomers in a solvent, and then initiating a polymerization reaction with an initiator to generate the copolymer adhesive.

[0014] Preferably, the mass ratio of the negative electrode active material to the copolymer binder is (8~9.5):(0.5~2).

[0015] Preferably, in the preparation process of the copolymer adhesive, the total mass fraction of acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate monomers in the solvent is 10-30%, and the molar ratio of acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate is (3~5):(1~2):(3~6).

[0016] A silicon anode includes a current collector and an anode paste coated on the current collector, wherein the anode paste is any one of the anode pastes described above.

[0017] A sulfide all-solid-state battery includes a positive electrode, a negative electrode, and a sulfide solid electrolyte, wherein the negative electrode is the aforementioned silicon negative electrode.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an adhesive, which is a triblock copolymer composed of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate monomers. The adhesive constructs a three-dimensional continuous ionic conductivity network, where the ether bonds abundant in the (ethylene glycol) methyl ether methacrylate and the lithium sulfonate segments provide additional single-ion conductors composed of lithium ions, enabling rapid ion transport. The carboxyl functional groups of the acrylic acid ensure strong adhesion between the adhesive and silicon particles and current collectors.

[0019] This invention also discloses a negative electrode slurry and a corresponding silicon negative electrode, employing in-situ chemical oxidative polymerization technology to directly coat a polypyrrole conductive layer onto the surface of nano-silicon particles. The core principle lies in initiating the polymerization of pyrrole monomers in an acidic reaction system containing nano-silicon using ammonium persulfate as an oxidant. During this process, strong hydrogen bonds are formed between the abundant silanol groups on the surface of the nano-silicon and the nitrogen atoms on the polypyrrole chains. This force guides the polymerization reaction to preferentially occur on the silicon surface and achieve a strong bond, thereby constructing a uniform and stable surface coating layer. Simultaneously, using ammonium persulfate (APS) as an oxidative initiator, the sulfate radicals generated under acidic conditions can abstract π electrons from the pyrrole monomers, initiating oxidative radical polymerization and constructing a polymer backbone with an extended π-conjugated structure. In this process, proton acids play a synergistic doping role: the protons they provide (H... + Simultaneous protonation and oxidation of the conjugated framework generate delocalized positive charge carriers; simultaneously, acid radical anions act as counterions to maintain electroneutrality. Thus, the long-range conjugated framework constructed through radical polymerization provides a charge transport channel, while simultaneous doping injects a high density of migratory charge carriers into this channel, resulting in high intrinsic electronic conductivity of the polypyrrole. Therefore, this coating layer not only serves as a physical coating but also constructs a highly conductive network structure in situ on the silicon particle surface, providing an efficient and stable electron transport channel for the active material silicon.

[0020] In the preparation of this composite anode, conductive polymer monomers form hydrogen bonds with the hydroxyl groups (-OH) on the surface of silicon particles, and polymerization occurs on the silicon particle surface, achieving structural stability of the composite silicon anode. Because the silicon particles are pre-coated with conductive polymer particles during the preparation process, the conductive polymer exhibits better bonding with the silicon particles compared to traditional methods of adding conductive agents. Furthermore, the conductive polymer has better dispersibility, allowing it to fully utilize its high conductivity electron properties, thereby replacing conductive carbon and reducing side reactions at the electrode / electrolyte interface. This maintains the cycle stability of the silicon anode while providing electron transport channels. A binder is simultaneously introduced into this anode material, and the binder's side chains contain negatively charged sulfonate groups (-SO3). - The binder exhibits strong electrostatic attraction with the positively charged PPy backbone after oxidative polymerization, while the lithium sulfonate segments provide additional single-ion conductors composed of lithium ions, thereby establishing a more robust three-dimensional conductive bonding network on the anode. This binder, by constructing a three-dimensional continuous ionic conductive network, enhances the electron and ion transport rates, improving the rate performance of the silicon anode.

[0021] This invention also discloses a sulfide all-solid-state battery based on this silicon anode. Through the application of this invention, the long-cycle performance of the battery is effectively improved, and an all-solid-state battery with high energy density and high current is successfully fabricated. Attached Figure Description

[0022] Figure 1 The infrared spectra of PPy and Si@PPy prepared in Example 1 of this invention are shown.

[0023] Figure 2 The image shows the infrared spectrum of the PASP adhesive prepared in Example 1 of this invention.

[0024] Figure 3 The diagram shows the long-cycle performance of Embodiments 1, 4 and 5 of the present invention.

[0025] Figure 4 The diagram shows the long-cycle performance of Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention.

[0026] Figure 5 The images show scanning electron microscope (SEM) images of the electrodes of Embodiment 1 and Comparative Example 1 before and after 100 cycles.

[0027] Figure 6 This is a comparison chart of the electronic conductivity of silicon anode materials in Examples 1, 2, 3 and Comparative Example 1 of the present invention.

[0028] Figure 7 This is a comparison chart of the ionic conductivity of the PASP adhesive and the polyacrylic acid (PAA) adhesive of this invention.

[0029] Figure 8 Differential scanning calorimetry curves of the PASP and PAA adhesives of this invention.

[0030] Figure 9 The images shown are scanning electron microscope images and energy dispersive spectra of Si@PPy prepared in Example 1 of this invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if 60 is listed for a specific parameter... 120 and 80 The range of 110 is understood to be 60. 110 and 80 The range of 120 is also expected. Furthermore, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1 3.1 4.1 5.2 3, 2 4 and 2 5. In this application, unless otherwise stated, the numerical range "a" "b" represents a shortened representation of any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0" represents a combination of real numbers from a to b. "5" indicates that all "0"s have been listed in this article. All real numbers between "5" and "0". "5" is simply an abbreviation for these numerical combinations. In addition, when a parameter is expressed as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0034] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0036] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B".

[0037] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0038] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0039] The first aspect of this invention discloses an adhesive, which is a copolymer (PASP) of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate. In this copolymer, carboxyl groups (–COOH) provided by the acrylic acid units act as strong hydrogen bond donors and acceptors, simultaneously anchoring hydroxyl groups (Si–OH) on the silicon surface and the oxide layer (Cu–O) on the copper current collector surface, forming a multi-coordination / hydrogen bond network. The lithium 4-styrene sulfonate units introduce highly dissociative lithium sulfonate groups, constructing localized lithium-ion enrichment microregions on the copolymer chain and enhancing the lithium salt dissociation ability through anion fixation effects. The poly(ethylene glycol) methyl ether methacrylate units provide a large number of flexible ether bonds (-O-) and long side chains, which both lower the glass transition temperature of the copolymer to improve chain segment mobility and buffer the volume strain during the charging and discharging process of silicon particles, and complex Li+ through the lone pair electrons of the ether oxygen atoms. + This promotes its directional migration along the side chains.

[0040] In some embodiments, the block copolymer adhesive has any one of the following structural formulas:

[0041]

[0042]

[0043] Where x ranges from 30 to 50, y ranges from 10 to 20, z ranges from 30 to 60, and n ranges from 10 to 30.

[0044] Because the three monomers of this adhesive can polymerize in pairs during the polymerization process, the structural formulas are as shown in the three forms above.

[0045] A second aspect of the present invention provides a negative electrode slurry comprising a silicon negative electrode active material, a binder, and a solvent; wherein the silicon negative electrode active material is a conductive polymer-coated silicon material; the binder is the aforementioned binder, and the conductive polymer monomer is pyrrole, aniline, or 3,4-dimethylformamide. Any one or more of ethylenedioxythiophene.

[0046] In this adhesive, silicon particles are coated in situ with conductive polymers (PPy / PANi / PEDOT). The monomers are protonated in an acidic environment and form hydrogen bonds with Si–OH on the silicon surface, thus achieving a uniform core-shell structure. The surface of each silicon particle is a dense conductive polymer layer or a conductive polymer film.

[0047] In some embodiments, the silicon particles are nano-silicon or micron-silicon, and the particle size of the selected Si can be 30nm-100 nm, 100nm-200 nm, 200nm-700 nm, or 700nm-1 μm.

[0048] Furthermore, the conductive polymer has a particle size of 30 nm-1 μm.

[0049] In some embodiments, the mass ratio of the silicon particles to the conductive polymer monomers is (1.2~2.4):1.

[0050] A third aspect of the present invention provides a method for preparing the above-mentioned negative electrode slurry, comprising the following steps: mixing a conductive polymer-coated silicon negative electrode active material with a copolymer binder to obtain a mixture, and ball milling the mixture to obtain a uniform negative electrode slurry; The method for preparing the negative electrode active material is as follows: a conductive polymer monomer is dispersed in an acidic solvent to obtain a monomer solution; silicon particles are added to the monomer solution, mixed evenly, and then an oxidant is added to generate a mixture; the mixture after reaction is filtered, washed, and dried to obtain a negative electrode active material with conductive polymer coated silicon. The copolymer adhesive is prepared by dissolving acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate monomers in a solvent, and then initiating a polymerization reaction with an initiator to generate the copolymer adhesive.

[0051] The preparation method of this invention utilizes an acidic solvent to simultaneously serve two stages: conductive polymer synthesis and binder synthesis. In the preparation of the active material, the acidic solvent provides a protic acid environment to protonate the pyrrole / aniline / EDOT monomers, thereby enhancing their oxidative polymerization activity and doping degree. In the binder synthesis, the acidic solvent maintains the protonated state of the acrylic acid carboxyl matrix, suppressing electrostatic repulsion caused by premature ionization and ensuring the efficiency of free radical polymerization chain growth. By employing ball milling, the active material and binder can be microscopically and uniformly dispersed in the slurry.

[0052] In the preparation of the copolymer adhesive, the total mass fraction of the three monomers in the solvent is 10-30%, preferably 15%-20%, to avoid the adhesive becoming too thick and causing gelation.

[0053] In some embodiments, the molar ratio of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate is (3~5):(1~2):(3~6).

[0054] A fourth aspect of the present invention provides a silicon anode, comprising a current collector and an anode slurry coated on the current collector, wherein the anode slurry is the aforementioned anode slurry. In this structure, during subsequent co-pressure bonding with a sulfide electrolyte, the flexible segments of the binder undergo controllable deformation, filling the gaps between electrolyte particles and achieving dense interfacial contact. This solves the technical problems of poor electrode / electrolyte solid-solid interface contact and contact failure during cycling in all-solid-state batteries.

[0055] In some embodiments, the fabrication of the silicon anode includes the following steps: Step 1: Disperse the conductive polymer monomer in a 1 M hydrochloric acid solution to obtain a monomer solution; add silicon particles (silicon powder) to the monomer solution, mix evenly, and then add ammonium persulfate (APS) oxidant at a mass ratio of 1:1 to the conductive polymer monomer. Under ice-water bath conditions of 0~5 °C, reactants are obtained through the synergistic effect of redox doping and proton acid doping; filter, wash, and dry the mixture after reaction to obtain a silicon anode active material coated with conductive polymer; preferably, the mass ratio of silicon particles to conductive polymer monomer is (1.2~2.4):1.

[0056] Step 2: Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate monomers are dissolved in a mixed solution of N,N-dimethylformamide and deionized water. Then, polymerization is initiated by APS (1% of the monomer mass) to generate a triblock copolymer binder PASP. The molar ratio of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate monomers in the binder is (3-5):(1-2):(3-6), the reaction temperature is 60-80 °C, and the reaction time is 6-10 hours. Preferably, the ratio of N,N-dimethylformamide to deionized water in the mixed solution is (3-7):(3-7).

[0057] Step 3: Add the binder and solvent obtained in Step 2 to the negative electrode active material obtained in Step 1 to prepare a mixture. Ball mill the mixture to obtain a uniform negative electrode slurry. Coat the negative electrode slurry onto the surface of the current collector, dry it, and then cut it to obtain a silicon composite negative electrode sheet. The mass ratio of silicon negative electrode active material to binder is (8~9.5):(0.5~2). The loading of the negative electrode slurry on the current collector is 0.8~2 mg / cm³. 2 The current collector is copper foil, and the coating thickness of the negative electrode paste is 80–200 μm.

[0058] As a preferred option, the mass ratio of negative electrode active material to binder is 9:1.

[0059] Preferably, the current collector is a copper foil with a thickness of 12 μm.

[0060] In a specific example, the method for preparing the negative electrode includes the following steps: Step 1: Weigh out a certain amount of pyrrole (Py), aniline (ANi), and 3,4-dimethylamine according to the designed mass ratio. Any one of ethylene dioxythiophene (EDOT) is dispersed in 1 M hydrochloric acid under ice-water bath conditions of 0~5 °C to obtain a monomer solution; silicon particles are added to the monomer solution, mixed evenly, and then oxidant APS is added. The mixture after reaction is filtered, washed, and dried to obtain a silicon anode active material coated with conductive polymer.

[0061] Step 2: First, dissolve 4-styrene sulfonic acid in deionized water, add lithium hydroxide and react for 30 min to obtain lithium 4-styrene sulfonate. Dissolve acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate monomer in a mixed solution of N,N-dimethylformamide and deionized water, and stir for 10-30 min to form a homogeneous solution. Add initiator APS to the homogeneous solution, freeze in liquid nitrogen, evacuate for 3-5 minutes, then introduce argon gas, thaw in room temperature water, and repeat the freezing and evacuation process three times to remove oxygen and introduce protective gas to prevent the inhibition of the polymerization reaction by oxygen. Raise the temperature to 60-80 °C and maintain for 4-10 hours to allow the polymerization reaction to occur. After the polymerization reaction, cool the product in an ice-water bath to terminate the reaction, resulting in a triblock copolymer.

[0062] Step 3: Add the negative electrode active material obtained in Step 1, the binder obtained in Step 2, and deionized water to the mushroom-shaped container. The ratio of negative electrode active material to binder is (8~9.5):(0.5~2), and the solid content is controlled at 20%~30%. Ball mill the mixture in a planetary ball mill at 300~350 rpm for 1 hour to ensure thorough mixing and obtain a uniformly dispersed negative electrode slurry. Apply the slurry to the copper foil current collector using an automatic coating agent, with a coating thickness of 80-200 μm and a loading rate controlled at 0.8-2 mg / cm³. 2 After coating, the electrode is placed in a vacuum oven to allow the solvent to evaporate completely, resulting in the final electrode. The electrode is then cut into 12 mm diameter electrode sheets using a cutting machine, which serve as the negative electrode for a sulfide all-solid-state battery.

[0063] The fifth aspect of this invention provides an application of a silicon anode in a sulfide all-solid-state battery, used to prepare a sulfide all-solid-state battery, wherein the solid electrolyte is Li6PS5Cl (LPSC) or Li 5.5 PS 4.5 Cl 1.5 and Li 10 GeP2S 12 One or more of the following. The cathode material is LiNi. 0.9 Co 0.05 Mn 0.05 O2(NCM90), LiNi0.8 Co 0.1 Mn 0.1 O2 (NCM811) and LiNi 0.5 Co 0.3 Mn 0.2 One or more of O2 (NCM532).

[0064] In this invention, the negative electrode active material is a silicon composite coated with a conductive polymer. The NH bonds on the surface of the conductive polymer monomers form hydrogen bonds with the hydroxyl groups (-OH) on the silicon surface, polymerizing on the silicon particle surface to achieve uniform coating of the silicon particles, thereby effectively improving the electronic conductivity of the silicon negative electrode. The binder is a triblock copolymer of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate. The abundant ether bonds in the poly(ethylene glycol) methyl ether methacrylate and the lithium sulfonate segments provide additional single-ion conductors composed of lithium ions, improving the problem of low intrinsic ionic conductivity and uneven lithium ion diffusion in the silicon negative electrode. This avoids stress concentration and structural damage caused by uneven lithium ion diffusion, improving the structural stability of the silicon negative electrode. During electrode fabrication, a highly efficient ion / electron transport channel is constructed inside the silicon negative electrode, simultaneously enhancing the structural stability of the electrode and enabling the battery to achieve long-term stable cycling.

[0065] In this invention, the core of the sulfide all-solid-state battery anode lies in the synergistic improvement of the electrode's electronic / ionic conductivity and structural stability through material design and interface control. The anode active material is a conductive polymer-coated silicon composite material based on hydrogen bonding. The NH groups in the polymer chain react with the hydroxyl groups (-OH) on the silicon surface to form a uniform coating layer, significantly enhancing electronic conductivity. Simultaneously, a triblock copolymer composed of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate is used as a binder. The abundant ether bonds and lithium sulfonate segments together form a single-ion conductor, effectively improving intrinsic ionic conductivity, promoting uniform lithium-ion migration, and suppressing stress concentration and particle breakage caused by local concentration gradients. This design constructs a highly efficient electron / ion dual-pathway transport network within the electrode and strengthens the overall structural integrity of the electrode, thereby endowing the battery with excellent long-cycle stability.

[0066] In a specific example, the preparation process of a sulfide-based all-solid-state battery anode sheet is as follows: 1 g of pyrrole is weighed according to the designed mass ratio and dispersed in 1 M hydrochloric acid under ice-water bath conditions to obtain a monomer solution; 2.4 g of silicon particles are added to the monomer solution, mixed evenly, and then 1 g of oxidant APS is added. The mixture is reacted for 1 h under ice-water bath conditions at 5 ℃. After filtration, washing, and drying, the conductive polymer-coated silicon anode active material Si@PPy is obtained. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate monomers are dissolved in a mixed solution of N,N-dimethylformamide and deionized water at a mass ratio of 4:1:5, with the three monomers accounting for 20% of the total mass fraction of the solution. An initiator, persulfate, is then added. Ammonium sulfate (APS), the initiator. Add 1% (by mass) of the initiator to a homogeneous solution, freeze in liquid nitrogen, and evacuate for 3 minutes. After 5 minutes, argon gas was introduced again, and the mixture was thawed in water at room temperature. This process of freezing and evacuation was repeated three times to remove oxygen and introduce a protective gas to prevent the inhibition of the polymerization reaction by oxygen. The polymerization reaction was carried out at 70 °C for 8 hours to generate the triblock copolymer binder PASP. Then, in a ball mill, the above-mentioned negative electrode active material and binder were prepared into a uniform slurry with a solid content of 25%. The ball-milled slurry was then coated onto a 12 μm thick copper current collector using a blade coating method. The negative electrode loading was set to 0.8~2 mg / cm³. 2 The coating thickness is 80~200 μm. Finally, the above electrode is kept in a vacuum drying oven at 80 ℃ for 12 h to obtain the final negative electrode.

[0067] In some embodiments of the present invention, the preparation process of an all-solid-state half-cell based on a sulfide all-solid-state battery anode includes the following steps: (1) The negative electrode active material and PASP binder were prepared at a mass ratio of 9:1, and a certain amount of deionized water was added to form a negative electrode slurry with a solid content of 25%. The slurry was further ball-milled in a planetary ball mill at a speed of 300~350 rpm for 60 min to obtain a uniform silicon negative electrode slurry.

[0068] (2) The slurry from (1) was uniformly coated onto a 12 μm thick copper foil using an automatic coating machine, with the negative electrode loading set to 0.8~2 mg / cm². 2 The coating thickness was set to 80~200 μm, and then the material was placed in a vacuum oven to dry and remove water. After drying, the material was cut into silicon anode sheets with a diameter of 12 mm, the mass of the sheets was weighed, and the active material loading was calculated.

[0069] (3) Transfer the electrode sheet prepared in (2) to a glove box filled with argon gas and assemble the sulfide all-solid-state battery. First, weigh 100 mg of sulfide solid electrolyte Li6PS5Cl (LPSC) and pour it into a polyether ether ketone (PEEK) ring sleeve with a diameter of 12 mm. Then, press the solid electrolyte at 175 MPa for 1 min to obtain a solid electrolyte sheet. Place the negative electrode sheet prepared in (2) into the mold and press it together with LPSC. Pre-press it at 175 MPa for 1 min, then press it to 350 MPa and hold it for 5 min. After holding the pressure, unload it. Then, place indium with a diameter of 12 mm and a thickness of 100 μm and ultrathin lithium with a thickness of 60 μm in sequence on the other side of the mold. Install the mold in the mold frame and press it to 175 MPa. Hold the pressure for 1 min so that lithium and indium form a lithium-indium alloy under pressure. Then, slowly depressurize to 75 MPa and tighten the screws. The sulfide all-solid-state half-cell assembly is completed.

[0070] (4) Perform electrochemical performance tests on the half-cell assembled in (3). The electrochemical performance was tested at -0.61 V to 0.88 V (0.01~1.5V, vs. Li). + Constant current charge-discharge tests were conducted within the range of / Li, with a theoretical capacity of 3500 mAh / g. Three cycles at 0.1 C were performed as a pre-cycle, followed by long-term cycling at 1 C. Before the start of cycling and after 100 cycles, the battery was disassembled and the surface morphology of the negative electrode was observed using scanning electron microscopy (SEM) to study the changes in the negative electrode at different cycling stages.

[0071] The following description, in conjunction with specific embodiments, provides further details.

[0072] Example 1 1 g of pyrrole (Py) was weighed and dispersed in 1 M hydrochloric acid under ice-water bath conditions to obtain a monomer solution; 1 g of oxidant APS was added, and the reaction was carried out at 5 °C under ice-water bath conditions for 1 h. The mixture after reaction was filtered, washed, and dried to obtain the conductive polymer polypyrrole PPy. The mass of the reaction product obtained was approximately 300 mg, and the reaction yield was 30%.

[0073] According to the mass ratio of nano-Si:Py = 1.8:1, 1 g of pyrrole (Py) was weighed and dispersed in 1M hydrochloric acid under ice-water bath conditions to obtain a monomer solution. 1.8 g of nano-silicon particles were added to the monomer solution, mixed evenly, and then 1 g of oxidant APS was added. The mixture was reacted for 1 h under ice-water bath conditions at 5 ℃. After filtration, washing, and drying, the conductive polymer-coated silicon anode active material nSi@PPy was obtained, which was named nSi@PPy61 according to the mass ratio of Si to PPy.

[0074] Figure 1 PPy, nSi@PPy, and pure nSi were characterized using Fourier transform infrared spectroscopy (FTIR). PPy and nSi@PPy were measured at 1554 cm⁻¹. -1 The C=C and CC antisymmetric stretching vibrations of the pyrrole ring appear at 1464 cm⁻¹. -1 Symmetrical stretching vibrations of the pyrrole rings at C=C and CC occur, and these vibrations occur at 904 cm⁻¹. -1 and 914 cm -1 A respiratory vibration peak of the pyrrole ring appears; nSi and nSi@PPy show a peak at 1587 cm⁻¹. -1 ~1616cm -1 A relatively broad hydrogen bond peak appeared nearby, and the peak intensity of nSi@PPy was significantly greater than that of nSi, proving that hydrogen bonds were formed between the Si-OH group and the -NH group on the pyrrole ring, thereby forming an electron transport network. Figure 9 The images show scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) of Si@PPy. The magnified SEM images reveal that Si particles are adhered together, indicating that PPy is effectively coated on the surface of the Si particles, thus constructing an electron transport network. The EDS spectra show a uniform distribution of Si, C, and N elements, demonstrating the successful synthesis of nSi@PPy.

[0075] nSi@PPy61 and nSi powders were pressed into sheets at 175 MPa pressure for 5 min using a mold. The electronic conductivity was measured by chronoamperometry. The test results are as follows: Figure 6 As shown, the electronic conductivity of nSi@PPy61 and nSi is 14.4 mS / cm and 1.1 mS / cm, respectively. The electronic conductivity of nSi@PPy61 is 12.1 times higher than that of nSi, which proves that the nSi@PPy composite silicon anode has better electron transport capability.

[0076] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.37 g of 4-styrene sulfonic acid was dissolved in 8 mL of deionized water, and 0.08 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 4:1:5. 0.58 g of acrylic acid, 2.88 g of poly(ethylene glycol) monomethyl ether methacrylate, and 8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 40 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70 °C and reacted for 8 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP.

[0077] Figure 2 Infrared spectra of the three monomers and PASP. 1721 cm⁻¹ -1 The peak at 1512 cm⁻¹ corresponds to the carbonyl (C=O) stretching vibration peak of the AA and PEGMA structural units. -1 and 1551 cm -1 The peak at 1593 cm⁻¹ corresponds to the C=C stretching vibration on the benzene ring in SS. -1 ~1637 cm -1 The peaks within the range correspond to the absorption peaks of the C=C double bonds on the main chain of AA, SS and PEGMA, while PASP does not have obvious absorption peaks in this range, proving the successful polymerization of the triblock copolymer.

[0078] The ionic conductivity of PASP polymer binder and commercially available polyacrylic acid (PAA) binder was tested using electrochemical impedance spectroscopy. The test results are as follows: Figure 7 As shown, the ionic conductivity of the PASP adhesive film and the PAA adhesive film is 2.53 × 10⁻⁶. -5 S / cm and 2.1×10 -6 S / cm. The lithium-ion conductivity of the PASP binder film is 12 times that of the PAA binder film. Compared with commercial PAA binders, PASP binder has a higher lithium-ion conductivity, which can effectively improve the rate performance and capacity utilization of silicon anodes.

[0079] The glass transition temperatures (Tg) of PASP polymer binder and PAA were determined by differential scanning calorimetry, and the results are as follows: Figure 8As shown, the glass transition temperature of PASP adhesive is -43.22 ℃, while that of PAA adhesive is 31.77 ℃. The lower glass transition temperature of PASP adhesive is mainly due to the weaker intermolecular forces of its weakly polar groups (hydroxyl and ester groups) compared to the strong hydrogen bonds of the carboxylic acid groups in PAA. Simultaneously, the steric hindrance of the methyl substituents and the flexibility of the side chains further reduce the resistance to chain segment movement. This lower glass transition temperature enhances the mobility of PASP chain segments.

[0080] 180 mg of nSi@PPy61 and 20 mg of PASP binder were added to a mushroom-shaped container, and deionized water was added to adjust the slurry solids content to 25%. The ball mill jar was placed in a planetary ball mill and milled at 350 rpm for 60 minutes to obtain a uniformly mixed negative electrode slurry. The slurry was then coated onto a clean Cu current collector surface using a blade coating method, with the negative electrode loading set to 0.8 mg / cm³. 2 The coating thickness was 80 μm. Subsequently, the coated electrode was placed in a vacuum drying oven at 80 °C for 12 hours to remove water, thereby obtaining the negative electrode.

[0081] The prepared negative electrode is used in a sulfide all-solid-state half-cell. The preparation process of this cell includes the following steps: Step 1: Using a manual punch, cut electrode sheets with a diameter of 12 mm from the electrode sheet coated with slurry. Transfer the cut electrode sheets to a glove box filled with argon gas for later use.

[0082] Step 2: Weigh 100 mg of sulfide solid electrolyte LPSC and grind it twice by hand in the same direction in a mortar. Place the ground electrolyte powder into a battery mold and press it at 175 MPa for 1 minute to obtain a solid electrolyte sheet. Then, stack the silicon anode sheet prepared in Step 1 with the solid electrolyte sheet and press them together. First, pre-press at 175 MPa for 1 minute, then increase the pressure to 350 MPa and hold for 5 minutes. After pressing, unload the mold.

[0083] Next, using a 12 mm diameter die, one 150 μm thick ultrathin lithium sheet and one 100 μm thick indium sheet were cut. The indium and lithium sheets were placed sequentially at the other end of the die, and the die was installed in a die holder. A pressure of 150 MPa was applied and held for 1 minute to allow the lithium and indium to form a lithium-indium alloy. The pressure was then slowly released to 75 MPa, and the die screws were tightened, thus completing the assembly of the sulfide all-solid-state half-cell.

[0084] Step 3: Perform electrochemical performance testing on the half-cell assembled in Step 2. Within the voltage window of -0.61 V to 0.88 V (0.01~1.5 V, vs. Li...),... +Constant current charge-discharge tests were conducted within the range of / Li, with a theoretical capacity of 3500 mAh / g. Three cycles at 0.1 C were performed as a pre-cycle, followed by a long-term cycle test at 1 C. The cycle test results are as follows: Figure 3 As shown, the electrode morphology before and after cycling is as follows: Figure 5 As shown, specifically, under the 1 C rate test conditions after pre-cycling, the discharge capacity was 2609.40 mAh / g, and after 450 cycles, the discharge capacity was 2444.24 mAh / g, with a capacity retention of 93.7%. The cycling stability was good, and the electrode surface morphology remained structurally stable and intact after cycling.

[0085] Example 2 According to the mass ratio of nSi:Py = 2.4:1, 1 g of pyrrole (Py) was weighed and dispersed in 1 M hydrochloric acid under ice-water bath conditions to obtain a monomer solution. 2.4 g of nano-silicon particles were added to the monomer solution, mixed thoroughly, and then 1 g of oxidant APS was added. The mixture was reacted for 1 h under ice-water bath conditions at 5 ℃. After filtration, washing, and drying, the conductive polymer-coated silicon anode active material nSi@PPy was obtained, and named nSi@PPy81 according to the mass ratio of nSi to PPy.

[0086] The preparation method, reaction conditions, and purification method of the triblock copolymer PASP (lithium 4-styrene sulfonate and poly(ethylene glycol) monomethyl ether methacrylate) were the same as in Example 1. The prepared nSi@PPy81 and PASP binder were applied to a silicon anode and a sulfide all-solid-state battery was assembled for testing, with all steps being the same as in Example 1.

[0087] Example 3 According to the mass ratio of nSi:Py = 1.2:1, 1 g of pyrrole (Py) was weighed and dispersed in 1 M hydrochloric acid under ice-water bath conditions to obtain a monomer solution. 1.2 g of nano-silicon particles were added to the monomer solution, mixed evenly, and then 1 g of oxidant APS was added. The mixture was reacted for 1 h under ice-water bath conditions at 5 ℃. After filtration, washing, and drying, the conductive polymer-coated silicon anode active material nSi@PPy was obtained, which was named nSi@PPy41 according to the mass ratio of nSi to PPy.

[0088] The preparation method, reaction conditions, and purification method of the triblock copolymer PASP (lithium 4-styrene sulfonate and poly(ethylene glycol) monomethyl ether methacrylate) were the same as in Example 1. The prepared nSi@PPy41 and PASP binder were applied to a silicon anode and a sulfide all-solid-state battery was assembled for testing, with all steps being the same as in Example 1.

[0089] Example 4 According to the mass ratio of nSi:ANi = 1.8:1, 1 g of aniline (ANi) was weighed and dispersed in 1M hydrochloric acid under ice-water bath conditions to obtain a monomer solution. 1.8 g of nano-silicon particles were added to the monomer solution, mixed thoroughly, and then 1 g of oxidant APS was added. The mixture was reacted for 1 h under ice-water bath conditions at 5 ℃. After filtration, washing, and drying, the conductive polymer-coated silicon anode active material nSi@PANi was obtained. Based on the mass ratio of nSi to PANi, it was named nSi@PANi61. The electronic conductivity test results are as follows: Figure 6 As shown.

[0090] The preparation method, reaction conditions, and purification method of the triblock copolymer PASP (propylene glycol monomethyl ether methacrylate) of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were the same as in Example 1. The prepared nSi@PANi61 and PASP binder were applied to a silicon anode and a sulfide all-solid-state battery was assembled for testing; all steps were the same as in Example 1. Cyclic test results are as follows: Figure 3 As shown, the specific performance is as follows: under the 1 C rate test condition after the pre-cycle, the discharge capacity is 2107.19 mAh / g, and after 330 cycles, the discharge capacity is 1710.24 mAh / g, with a capacity retention rate of 81.2%.

[0091] Example 5 Weigh 1 g of 3,4 according to the mass ratio of nSi :EDOT = 1.8 : 1. Ethylene dioxythiophene (EDOT) was dispersed in 1 M hydrochloric acid under ice-water bath conditions to obtain a monomer solution. 1.8 g of nano-silicon particles were added to the monomer solution, mixed thoroughly, and then 1 g of oxidant APS was added. The mixture was reacted at 5 °C for 1 h under ice-water bath conditions. The resulting mixture was filtered, washed, and dried to obtain a conductive polymer-coated silicon anode active material, nSi@PEDOT. Based on the mass ratio of nSi to PEDOT, it was named nSi@PEDOT61. The electronic conductivity test results are as follows: Figure 6 As shown.

[0092] The preparation method, reaction conditions, and purification method of the triblock copolymer PASP (propylene glycol monomethyl ether methacrylate) of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were the same as in Example 1. The prepared nSi@PEDOT61 and PASP binder were applied to a silicon anode and a sulfide all-solid-state battery was assembled for testing; all steps were the same as in Example 1. Cyclic test results are as follows: Figure 3 As shown, the specific performance is as follows: under the 1 C rate test condition after the pre-cycle, the discharge capacity is 2621.28 mAh / g, and the discharge capacity is 2000.75 mAh / g after 450 cycles, with a capacity retention rate of 76.3%.

[0093] Example 6 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0094] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.37 g of 4-styrene sulfonic acid was dissolved in 8 mL of deionized water, and 0.08 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 3:1:6. 0.43 g of acrylic acid, 3.46 g of poly(ethylene glycol) monomethyl ether methacrylate, and 8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 43 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 4 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP316.

[0095] The prepared nSi@PPy61 and PASP316 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0096] Example 7 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0097] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.37 g of 4-styrene sulfonic acid was dissolved in 8 mL of deionized water, and 0.08 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 5:1:4. 0.72 g of acrylic acid, 2.30 g of poly(ethylene glycol) monomethyl ether methacrylate, and 8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 35 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 4 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP514.

[0098] The prepared nSi@PPy61 and PASP514 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0099] Example 8 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0100] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.74 g of 4-styrene sulfonic acid was dissolved in 8 mL of deionized water, and 0.16 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 3:2:5. 0.43 g of acrylic acid, 2.88 g of poly(ethylene glycol) monomethyl ether methacrylate, and 8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 41 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 4 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP325.

[0101] The prepared nSi@PPy61 and PASP325 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0102] Example 9 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0103] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.74 g of 4-styrene sulfonic acid was dissolved in 8 mL of deionized water, and 0.16 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 4:2:4. 0.58 g of acrylic acid, 2.30 g of poly(ethylene glycol) monomethyl ether methacrylate, and 8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 38 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 4 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP424.

[0104] The prepared nSi@PPy61 and PASP424 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0105] Example 10 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0106] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.74 g of 4-styrene sulfonic acid was dissolved in 8 mL of deionized water, and 0.16 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 5:2:3. 0.58 g of acrylic acid, 1.73 g of poly(ethylene glycol) monomethyl ether methacrylate, and 8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 32 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 4 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP523.

[0107] The prepared nSi@PPy61 and PASP523 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0108] Example 11 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0109] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.37 g of 4-styrene sulfonic acid was dissolved in 11.2 mL of deionized water, and 0.08 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 4:1:5. 0.58 g of acrylic acid, 2.88 g of poly(ethylene glycol) monomethyl ether methacrylate, and 4.8 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 40 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 8 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP-1.

[0110] The prepared nSi@PPy61 and PASP-1 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0111] Example 12 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0112] 4-Styrene sulfonic acid and lithium hydroxide were added at a molar ratio of 1:1. 0.37 g of 4-styrene sulfonic acid was dissolved in 4.8 mL of deionized water, and 0.08 g of lithium hydroxide was added. The reaction was carried out for 30 min to obtain a lithium 4-styrene sulfonate solution. Acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate were added at a molar ratio of 4:1:5. 0.58 g of acrylic acid, 2.88 g of poly(ethylene glycol) monomethyl ether methacrylate, and 11.2 mL of N,N-dimethylformamide were added to the prepared lithium 4-styrene sulfonate solution to form a homogeneous solution. The three monomers accounted for 20% of the total mass of the solution. 40 mg of ammonium persulfate initiator was added, with the initiator mass being 1% of the solute mass. The homogeneous solution was then frozen solid in liquid nitrogen, evacuated for 5 minutes, and then purged with argon gas. The solution was then thawed in water at room temperature, and the freezing and evacuation process was repeated three times. The reaction flask was heated to 70°C and reacted for 8 hours. After polymerization, the product was cooled in an ice-water bath to terminate the reaction, yielding the triblock copolymer PASP-2.

[0113] The prepared nSi@PPy61 and PASP-2 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0114] Example 13 In this embodiment, the reaction conditions of PASP were adjusted compared to Example 1, with the reaction temperature set at 60°C and the reaction time set at 4 h, to obtain adhesive PASP-3.

[0115] The prepared nSi@PPy61 and PASP-3 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0116] Example 14 In this embodiment, the reaction conditions of PASP were adjusted compared to Example 1, with the reaction temperature set at 80°C and the reaction time set at 10 h, to obtain adhesive PASP-4.

[0117] The prepared nSi@PPy61 and PASP-4 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0118] Example 15 In this embodiment, compared to Example 1, the total mass fraction of the three monomers—acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate—in the homogeneous solution is 10%, resulting in binder PASP-5.

[0119] The prepared nSi@PPy61 and PASP-5 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0120] Example 16 In this embodiment, compared to Example 1, the total mass fraction of the three monomers—acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) monomethyl ether methacrylate—in the homogeneous solution is 30%, resulting in adhesive PASP-6.

[0121] The prepared nSi@PPy61 and PASP-6 binders were applied to the silicon anode and a sulfide all-solid-state battery was assembled and tested. All steps were the same as in Example 1.

[0122] Example 17 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 and binder PASP-6 are the same as in Example 1.

[0123] 160 mg of nSi@PPy61 and 40 mg of PASP binder were added to a mushroom-shaped container, and deionized water was added to adjust the slurry solids content to 25%. The ball mill jar was placed in a planetary ball mill and milled at 350 rpm for 60 minutes to obtain a uniformly mixed negative electrode slurry. The slurry was then coated onto a clean Cu current collector surface using a blade coating method, with the negative electrode loading set to 0.8 mg / cm³. 2 The coating thickness was 80 μm. Subsequently, the coated electrode was placed in a vacuum drying oven at 80 °C for 12 hours to remove water, thus obtaining the negative electrode. The prepared negative electrode was then assembled into a sulfide all-solid-state battery for testing, with all steps identical to those in Example 1.

[0124] Example 18 The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 and the binder PASP are the same as in Example 1.

[0125] 190 mg of nSi@PPy61 and 10 mg of PASP binder were added to a mushroom-shaped container, and deionized water was added to adjust the slurry solids content to 25%. The ball mill jar was placed in a planetary ball mill and milled at 350 rpm for 60 minutes to obtain a uniformly mixed negative electrode slurry. The slurry was then coated onto a clean Cu current collector surface using a blade coating method, with the negative electrode loading set to 0.8 mg / cm³. 2 The coating thickness was 80 μm. Subsequently, the coated electrode was placed in a vacuum drying oven at 80 °C for 12 hours to remove water, thus obtaining the negative electrode. The prepared negative electrode was then assembled into a sulfide all-solid-state battery for testing, with all steps identical to those in Example 1.

[0126] Comparative Example 1 Commercially available conductive carbon black (Super P) and commercially available binder polyacrylic acid (PAA) were used as comparative examples.

[0127] 160 mg of nano-silicon particles (nSi), 20 mg of conductive carbon black (Super P), and 20 mg of polyacrylic acid (PAA) binder were added to a mushroom-shaped container along with five quartz grinding balls. Deionized water was added to the mushroom-shaped container to bring the solid content of the slurry to 25%. The container was then placed in a planetary ball mill and milled at 350 rpm for 60 minutes. After milling, the slurry was coated using a blade coating method, with a silicon anode loading of 0.8 mg / cm² and a coating thickness of 80 μm. After coating, the electrode was placed in a drying oven and dried at 80 °C for 12 hours to remove the solvent and obtain the silicon anode electrode sheet.

[0128] The prepared silicon anode was applied to a sulfide all-solid-state battery, and all steps were the same as in Example 1. Cyclic test results are as follows: Figure 4 As shown, the electrode morphology before and after cycling is as follows: Figure 5 As shown, the specific performance is as follows: under 1C rate testing conditions after pre-cycling, the discharge capacity is 1649.86 mAh / g, and after 450 cycles, the discharge capacity is 886.85 mAh / g, with a capacity retention of 53.7%, indicating poor rate and cycle performance. Cracking appeared on the electrode surface after cycling, demonstrating poor cycle stability.

[0129] Comparative Example 2 The adhesive used was the commercial adhesive polyacrylic acid (PAA) as a comparative example.

[0130] The preparation method, reaction conditions, and purification method of the conductive polymer-coated silicon anode active material nSi@PPy61 are the same as in Example 1.

[0131] 180 mg of nSi@PPy61 and 20 mg of polyacrylic acid (PAA) binder were added to a mushroom-shaped container, along with five quartz milling balls. Deionized water was added to the mushroom-shaped container to bring the solid content of the slurry to 25%. The container was then placed in a planetary ball mill and milled at 350 rpm for 60 minutes. After milling, the slurry was coated using a blade coating method, with a silicon anode loading of 0.8 mg / cm² and a coating thickness of 80 μm. After coating, the electrode was placed in a drying oven and dried at 80 °C for 12 hours to remove the solvent and obtain the silicon anode electrode sheet.

[0132] The prepared silicon anode was applied to a sulfide all-solid-state battery, and all steps were the same as in Example 1. Cyclic test results are as follows: Figure 4As shown, under the 1 C rate test conditions after the pre-cycle, the discharge capacity is 2042.77 mAh / g, and after 450 cycles, the discharge capacity is 1124.09 mAh / g, with a capacity retention rate of 55.0%.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adhesive, characterized in that, The adhesive is a block copolymer of acrylic acid, lithium 4-styrene sulfonate, and poly(ethylene glycol) methyl ether methacrylate.

2. The adhesive according to claim 1, characterized in that, The block copolymer has a structural formula that is any one of the following three structural formulas: Where x ranges from 30 to 50, y ranges from 10 to 20, z ranges from 30 to 60, and n ranges from 10 to 30.

3. A negative electrode slurry, characterized in that, The process includes a silicon anode active material, a binder, and a solvent; the silicon anode active material is a material in which conductive polymers coat silicon particles; the binder is the binder described in claim 1 or 2, and the conductive polymer is pyrrole, aniline, or 3,4-dimethylformamide. Any one or more of ethylenedioxythiophene.

4. The negative electrode slurry according to claim 3, characterized in that, The silicon particles are nano-silicon or micron-silicon, and the particle size range of the silicon particles is 30 nm-1 μm.

5. The negative electrode slurry according to claim 3, characterized in that, The mass ratio of silicon particles to conductive polymer monomers is (1.2~2.4):

1.

6. A method for preparing the negative electrode slurry according to claim 3, characterized in that, The process includes the following steps: mixing the conductive polymer-coated silicon negative electrode active material with the copolymer binder in a solvent to obtain a mixture, and ball milling the mixture to obtain a uniform negative electrode slurry; The method for preparing the negative electrode active material is as follows: a conductive polymer monomer is dispersed in an acidic solvent to obtain a monomer solution; silicon particles are added to the monomer solution, mixed evenly, and an oxidant is added to generate a mixture; the mixture after reaction is filtered, washed, and dried to obtain a negative electrode active material with conductive polymer coated silicon. The copolymer adhesive is prepared by dissolving acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate monomers in a solvent, and then initiating a polymerization reaction with an initiator to generate the copolymer adhesive.

7. The preparation method according to claim 6, characterized in that, The mass ratio of the negative electrode active material to the copolymer binder is (8~9.5):(0.5~2).

8. The preparation method according to claim 6, characterized in that, In the preparation of the copolymer adhesive, the total mass fraction of acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate monomers in the solvent is 10-30%, and the molar ratio of acrylic acid, lithium 4-styrene sulfonate and poly(ethylene glycol) methyl ether methacrylate is (3~5):(1~2):(3~6).

9. A silicon anode, characterized in that, It includes a current collector and a negative electrode slurry coated on the current collector, wherein the negative electrode slurry is the negative electrode slurry according to any one of claims 3-5.

10. A sulfide all-solid-state battery, characterized in that, It includes a positive electrode, a negative electrode, and a sulfide solid electrolyte, wherein the negative electrode is the silicon negative electrode as described in claim 9.

Images