All-solid-state battery negative electrode sheet, all-solid-state battery, and manufacturing method

Abstract

The application provides a kind of all-solid-state battery negative electrode sheet, all-solid-state battery and preparation method, it is related to battery technical field.The all-solid-state battery negative electrode sheet introduces specific kind of inorganic substance ferroelectric I with piezoelectric effect and high viscoelastic piezoelectric polymer I with piezoelectric effect, uses system own expansion stress, inorganic substance ferroelectric I and piezoelectric polymer I are forced to polarize spontaneously under the condition of external voltage and generate electric field, it is favorable to accelerate the interface and lithium sub migration inside negative electrode, piezoelectric polymer I acts as binder and ion transport carrier, adapts to material intrinsic volume change.The application also provides an all-solid-state battery, inorganic substance ferroelectric and piezoelectric polymer are introduced simultaneously in negative electrode sheet and solid electrolyte layer, the process is equivalent to increase periodic ion pump in the electrode sheet, so as to reduce the overall impedance of solid-state battery charging process, improve cycle life and rate performance.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to an all-solid-state battery negative electrode, an all-solid-state battery, and a preparation method thereof. Background Technology

[0002] Currently, the following problems are common in all-solid-state battery systems (high-nickel cathode to high-silicon-doped anode): (1) failure of the interface between the electrolyte layer and the cathode and anode plates; (2) failure of contact between the active particles inside the high-silicon anode and the electrolyte. The space charge layer (carrier depletion) and the large volume change of the anode are important reasons for the above problems, making it difficult for ion transport and diffusion inside the anode and at the electrolyte interface between the cathode and anode plates, ultimately leading to a sharp decrease in the cycle life and rate performance of the solid-state battery.

[0003] Existing solutions primarily aim to improve the cycle life and rate performance of all-solid-state batteries by optimizing the composition and structure of the electrolyte material and refining the fabrication process of the negative electrode. For example, some researchers have proposed introducing inorganic fillers, such as alumina and zirconium oxide, into the electrolyte layer to enhance its mechanical strength and ion conductivity. Additionally, other researchers have improved the mechanical strength and cycle stability of the negative electrode by introducing modified binders, such as polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN). While these existing solutions can improve the cycle life and rate performance of all-solid-state batteries to some extent, the improvement is limited and they do not address the fundamental problems.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] In view of the shortcomings and defects of the existing technology, the present invention aims to provide an all-solid-state battery negative electrode sheet, an all-solid-state battery, and a preparation method thereof.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] The primary objective of this invention is to provide an all-solid-state battery negative electrode sheet, comprising a negative electrode current collector and a negative electrode material film disposed on the surface of the negative electrode current collector;

[0008] The negative electrode material membrane includes: a negative electrode active material, a binder, a conductive agent, an inorganic ferroelectric material I, a piezoelectric polymer I, and a sulfide electrolyte;

[0009] The inorganic ferroelectric material I includes at least one of barium titanate, lead zirconate titanate, lithium niobate, or bismuth layered structure compound.

[0010] The piezoelectric polymer I includes at least one of polyvinylidene fluoride, polyvinylidene fluoride, trifluoroethylene-polyvinylidene fluoride copolymer, polyethylene terephthalate, polylactic acid, or aromatic polyurea.

[0011] Furthermore, based on the above-mentioned technical solution of the present invention, the mass ratio of the negative electrode active material, binder, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte is (50-90):(2-10):(1-10):(1-10):(1-10):(10-30);

[0012] And / or, the particle size of the inorganic ferroelectric material I is 1-20 μm;

[0013] And / or, the inorganic ferroelectric material I includes barium titanate;

[0014] And / or, the piezoelectric polymer I comprises trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid, wherein the mass ratio of trifluoroethylene-polyvinylidene fluoride copolymer to polylactic acid is (1-5):(1-5).

[0015] Furthermore, based on the above-mentioned technical solution of the present invention, the negative electrode active material includes one or more of silicon-carbon, silicon-oxygen, silicon, or graphite.

[0016] And / or, the adhesive comprises one or more of PTFE, PEO, PVDF or SBR;

[0017] And / or, the conductive agent includes at least one of conductive carbon black, carbon nanotubes, or graphene;

[0018] And / or, the sulfide solid electrolyte includes at least one of LPSCl, LPSBr, or LPSI.

[0019] The second objective of this invention is to provide a method for preparing the all-solid-state battery negative electrode sheet as provided in the first objective of this invention, comprising the following steps:

[0020] (a) Mix and stir the negative electrode active material, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte to obtain powder I;

[0021] (b) Mix powder I and binder to obtain powder II;

[0022] Powder II is heated and kept at a constant temperature to obtain loose powder III;

[0023] (c) Powder III is subjected to air jet milling to obtain powder IV in a filamentous state;

[0024] (d) The powder IV is rolled into a film to obtain the negative electrode material film;

[0025] (e) The negative electrode material film and the negative electrode current collector are bonded and rolled together to obtain an all-solid-state negative electrode sheet.

[0026] Furthermore, based on the above technical solution of the present invention, in step (a), the mixing speed is 300-500 rpm and the mixing time is 20-60 min;

[0027] And / or, in step (b), the mixing speed is 1000-1500 rpm, and the mixing time is 20-60 min; and / or, the heating and holding temperature is 40-70℃, and the heating and holding time is 20-40 min; and / or, the density of powder III is 0.5-0.8 g / cm³. 3 ;

[0028] And / or, in step (c), the airflow pressure during air jet milling is 0.3-0.8 mPa; and / or, the density of powder IV is 0.5-0.8 g / cm³. 3 ;

[0029] And / or, in step (d), roll forming includes vertical roll forming and horizontal roll forming, and the pressure of roll forming is 3-7T;

[0030] And / or, in step (e), the thickness of the all-solid-state negative electrode is 60-110 μm, and the areal density is 80-180 g / m². 2 .

[0031] The third objective of this invention is to provide an all-solid-state battery, comprising a positive electrode, a solid electrolyte layer, and a negative electrode, wherein the positive electrode and the negative electrode are stacked sequentially, and the solid electrolyte layer is disposed between two adjacent positive and negative electrode sheets;

[0032] The negative electrode sheet is the all-solid-state battery negative electrode sheet provided by the first objective of this invention or the all-solid-state battery negative electrode sheet prepared by the preparation method provided by the second objective of this invention;

[0033] The solid electrolyte layer comprises inorganic ferroelectric II, piezoelectric polymer II, and sulfide electrolyte;

[0034] The inorganic ferroelectric material II includes at least one of barium titanate, lead zirconate titanate, lithium niobate, or bismuth layered structure compounds.

[0035] The piezoelectric polymer II includes at least one of polyvinylidene fluoride, polyvinylidene fluoride, trifluoroethylene-polyvinylidene fluoride copolymer, polyethylene terephthalate, polylactic acid, or aromatic polyurea.

[0036] Furthermore, based on the above technical solution of the present invention, the mass ratio of inorganic ferroelectric II, piezoelectric polymer II and sulfide electrolyte in the solid electrolyte layer is (5-10):(5-10):(80-95);

[0037] And / or, the sulfide solid electrolyte includes at least one of LPSCl, LPSBr, or LPSI.

[0038] Furthermore, based on the above-mentioned technical solution of the present invention, the positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on the surface of the positive current collector;

[0039] The positive electrode material layer includes: positive electrode active material, binder, conductive agent and sulfide electrolyte, and the mass ratio of the positive electrode active material, binder and conductive agent and sulfide electrolyte is (60-90):(1-10):(1-10):(10-40).

[0040] The fourth objective of this invention is to provide a method for preparing an all-solid-state battery as provided in the third objective of this invention, comprising the following steps:

[0041] S1. Disperse the mixture obtained by ball milling inorganic ferroelectric II, piezoelectric polymer II and sulfide electrolyte in a solvent to obtain a solid electrolyte slurry;

[0042] S2. Coat the surface of the negative electrode sheet with solid electrolyte slurry and dry it to obtain a negative electrode sheet with a solid electrolyte layer on the surface;

[0043] S3. The positive electrode and the negative electrode with a solid electrolyte layer formed on the surface are stacked together, and the solid electrolyte layer is located between two adjacent positive and negative electrodes. Then, hot pressing is performed to obtain an all-solid-state battery.

[0044] Furthermore, based on the above technical solution of the present invention, in step S1, the ball milling time is 2-5 hours and the ball milling speed is 800-1200 rpm.

[0045] And / or, in step S1, dispersion is accompanied by stirring, the dispersion temperature is 40-50℃, the vacuum degree used during dispersion is ≥-90kPa, the rotation speed is 1200-1800rpm, the stirring time is 3-7h, and the solid content of the solid electrolyte slurry is controlled to be 30-80%.

[0046] And / or, in step S2, the drying is vacuum drying, the drying temperature is 70-90℃, and the drying time is 6-12h;

[0047] And / or, in step S3, the hot pressing temperature is 70-90℃, the hot pressing pressure is 800-1200KG, and the holding time is 30-90s.

[0048] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0049] (1) The present invention provides an all-solid-state battery negative electrode sheet, which introduces a specific type of inorganic ferroelectric material I with piezoelectric effect and a polymer with high viscoelasticity (elastic modulus) and piezoelectric effect (piezoelectric polymer I). Utilizing the system's own expansion stress, the inorganic ferroelectric material I and the piezoelectric polymer I are subjected to force and spontaneously polarize to generate an electric field under the condition of an external voltage, which is conducive to accelerating the migration of lithium ions at the interface and inside the negative electrode. The piezoelectric polymer I acts as a binder and ion transport carrier, adapting to the intrinsic volume change of the material. At the same time, when the negative electrode volume shrinks during discharge, the electric field disappears, forming a periodic piezoelectric effect electric field, thereby reducing the overall impedance of the battery and improving cycle life and rate performance.

[0050] (2) This invention provides an all-solid-state battery, which simultaneously introduces inorganic ferroelectric materials (inorganic ferroelectric material I and inorganic ferroelectric material II) and piezoelectric polymers (piezoelectric polymer I and piezoelectric polymer II) into the negative electrode and the solid electrolyte layer. Utilizing the system's own expansion stress, the inorganic materials and polymers spontaneously polarize under the influence of an external voltage, generating an electric field. This is beneficial for accelerating lithium migration at the interface and inside the negative electrode. The polymer acts as a binder and ion transport carrier, adapting to the intrinsic volume changes of the material. During discharge, as the volume of the electrode shrinks, the piezoelectric field gradually weakens until it disappears. The process is equivalent to adding periodic ion pumps inside the electrode and at the interface, thereby reducing the overall impedance of the solid-state battery during charging and improving cycle life and rate performance. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the piezoelectric phenomenon of piezoelectric materials (inorganic ferroelectrics and piezoelectric polymers) under pressure. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0053] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0054] According to a first aspect of the present invention, an all-solid-state battery negative electrode sheet is provided, comprising a negative electrode current collector and a negative electrode material film disposed on the surface of the negative electrode current collector;

[0055] The negative electrode material membrane includes: negative electrode active material, binder, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I, and sulfide electrolyte;

[0056] Among them, inorganic ferroelectric material I includes at least one of barium titanate (BaTiO3), lead zirconium titanate (PZT), lithium niobate (LiNbO3) or bismuth layered structure compound (such as BiFeO3);

[0057] Piezoelectric polymer I includes at least one of polyvinylidene fluoride, polyvinylidene fluoride, trifluoroethylene-polyvinylidene fluoride copolymer (P(VDF-TRFE)), polyethylene terephthalate (PET), polylactic acid (PLA), or aromatic polyurea.

[0058] In the negative electrode of this invention, a specific type of inorganic ferroelectric material I with piezoelectric effect and a polymer with high viscoelasticity (elastic modulus) and piezoelectric effect (piezoelectric polymer I) are introduced. Utilizing the system's own expansion stress, the inorganic ferroelectric material I and the piezoelectric polymer I spontaneously polarize under the influence of an external voltage, generating an electric field (e.g., ...). Figure 1 As shown, this is beneficial for accelerating lithium migration inside the negative electrode and at the interface between the negative electrode sheet and the solid electrolyte layer. The piezoelectric polymer I acts as a binder and ion transport carrier, adapting to the intrinsic volume changes of the material. At the same time, as the volume of the negative electrode shrinks during discharge and the electric field disappears, a periodic piezoelectric effect electric field is formed, thereby reducing the overall impedance of the battery and improving cycle life and rate performance.

[0059] The specific type of inorganic ferroelectric material I and piezoelectric polymer I is selected, which directly affects the performance of the negative electrode.

[0060] In a preferred embodiment of the technical solution of the present invention, the inorganic ferroelectric material I comprises barium titanate. Barium titanate is chosen as the inorganic ferroelectric material I primarily due to cost considerations and the requirement for a high dielectric constant.

[0061] In a preferred embodiment of the technical solution of the present invention, the piezoelectric polymer I comprises polylactic acid and trifluoroethylene-polyvinylidene fluoride copolymer. Trifluoroethylene-polyvinylidene fluoride copolymer (P(VDF-TRFE)) exhibits excellent viscoelasticity and ionic conductivity, while polylactic acid is sensitive to piezoelectric effects under stress. Combining these two materials as piezoelectric polymer I achieves complementary piezoelectric properties, toughness, and viscoelasticity. Furthermore, experimental verification has shown that when polylactic acid and trifluoroethylene-polyvinylidene fluoride copolymer are compounded, a mass ratio of (1-5):(1-5) (e.g., 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 3:1, 4:1, or 5:1, etc.), and more preferably 1:1, achieves a better compounding effect.

[0062] As an optional embodiment of the technical solution of the present invention, the particle size of the inorganic ferroelectric material I is 1-20 μm. Typical non-limiting particle sizes are 1 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or 20 μm. Inorganic ferroelectric materials I with particle sizes within the above range are not prone to agglomeration and can be uniformly dispersed internally during electrode processing.

[0063] As an optional embodiment of the technical solution of the present invention, the conductive agent includes at least one of conductive carbon black, carbon nanotubes (CNTs) or graphene.

[0064] As an optional embodiment of the technical solution of the present invention, the mass ratio of the negative electrode active material, binder, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I, and sulfide electrolyte is (50-90):(2-10):(1-10):(1-10):(1-10):(10-30); typical but non-limiting mass ratios are 50:2:2:8:8:30 and 50:5:5: The possible ratios are 5:5:30, 60:5:5:5:5:20, 60:2:2:3:3:30, 60:10:4:3:3:20, 60:10:10:5:5:10, 65:2:2:3:3:25, 65:2:1:1:9:22, 70:2:3:1:9:15, 75:2:3:2:3:15, 80:2:1:1:1:15, etc. It should be noted that the mass proportion of inorganic ferroelectric material I in the negative electrode film should not be too large, otherwise it may affect the cell's energy density, leading to a mismatch in the dynamics of the positive and negative electrodes. Conversely, the mass proportion of inorganic ferroelectric material I in the negative electrode film should not be too small, otherwise the piezoelectric effect may not be achieved, resulting in a weak and unevenly distributed self-generated field. Similarly, the mass percentage of piezoelectric polymer I in the negative electrode material film should not be too large, otherwise it may affect the ionic conductivity of the electrode. The mass percentage of piezoelectric polymer I in the negative electrode material film should not be too small, otherwise it may be unable to adapt to the particle shrinkage caused by the electrode volume effect, resulting in cracking and thus causing the ionic electron conduction network to break.

[0065] As an optional embodiment of the technical solution of the present invention, the negative electrode active material includes silicon-carbon (SiC) and silicon-oxygen (SiO). X One or more of silicon (Si) or graphite.

[0066] As an optional embodiment of the technical solution of the present invention, the adhesive includes one or more of polytetrafluoroethylene (PTFE), polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), or styrene-butadiene rubber (SBR).

[0067] As an optional embodiment of the technical solution of the present invention, the sulfide solid electrolyte includes at least one of LPSCl, LPSBr or LPSI, preferably LPSCl;

[0068] And / or, the sulfide solid electrolyte has a particle size of 300-700 nm and an average particle size of 500-700 nm.

[0069] According to a second aspect of the present invention, a method for preparing an all-solid-state battery negative electrode sheet is provided, comprising the following steps:

[0070] (a) Mix and stir the negative electrode active material, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte to obtain powder I;

[0071] (b) Mix powder I and binder to obtain powder II;

[0072] Powder II is heated and kept at a constant temperature to obtain loose powder III;

[0073] (c) Powder III is subjected to air jet milling to obtain powder IV in a filamentous state;

[0074] (d) The powder IV is rolled into a film to obtain the negative electrode material film;

[0075] (e) The negative electrode material film and the negative electrode current collector are bonded and rolled together to obtain an all-solid-state negative electrode sheet.

[0076] Since sulfide electrolytes are not solvent-resistant, this invention uses a dry method to prepare the negative electrode sheet for all-solid-state batteries. The dry electrode sheet can maintain the good electrical properties of the material.

[0077] As an optional embodiment of the technical solution of the present invention, in step (a), the mixing speed is 300-500 rpm, for example, 300 rpm, 400 rpm or 500 rpm, and the mixing time is 20-60 min, for example, 20 min, 30 min, 40 min or 60 min.

[0078] As an optional embodiment of the technical solution of the present invention, in step (b), the mixing speed is 1000-1500 rpm, for example, 1000 rpm, 1200 rpm, 1400 rpm or 1500 rpm, and the mixing time is 20-60 min, for example, 20 min, 30 min, 40 min or 60 min.

[0079] And / or, the heating and holding temperature is 40-70℃, such as 40℃, 50℃, 60℃ or 70℃, etc., and the heating and holding time is 20-40min, such as 20min, 30min or 40min, etc.;

[0080] And / or, the density of powder III is 0.5-0.8 g / cm³. 3 For example, 0.5g / cm 3 0.6g / cm 3 or 0.8g / cm 3 wait.

[0081] As an optional embodiment of the technical solution of the present invention, in step (c), the airflow pressure during air jet milling is 0.3-0.8 mPa, for example, 0.3 mPa, 0.5 mPa, 0.6 mPa, or 0.8 mPa; and / or, the density of powder IV is 0.5-0.8 g / cm³. 3 For example, 0.5g / cm 3 0.6g / cm 3 0.7g / cm 3 0.76 g / cm 3 or 0.8g / cm 3 wait.

[0082] As an optional embodiment of the technical solution of the present invention, in step (d), the roll forming includes vertical roll forming and horizontal roll forming, and the pressure of roll forming is 3-7T.

[0083] For example, powder IV is subjected to vertical roller pressing. Powder IV passes through the gap between two hot pressing rollers from top to bottom and is shaped under the extrusion of the two hot pressing rollers. The pressure of vertical roller pressing is 3-7T, for example, 3T, 5T or 7T. The temperature of vertical roller pressing is 80-120℃, for example, 80℃, 90℃, 100℃, 110℃ or 120℃. The width of the gap between the two hot pressing rollers is 1-2μm, for example, 1μm, 1.5μm or 2μm.

[0084] After vertical roller pressing, powder IV is subjected to horizontal roller pressing. Powder IV passes through the gap between two horizontal rollers in the horizontal direction and is formed into a negative electrode material film under the extrusion action of the two horizontal rollers. The pressure of horizontal roller pressing is 3-7T, for example, 3T, 5T or 7T. The width of the gap between the two horizontal rollers is 1-2μm, for example, 1μm, 1.5μm or 2μm. The thickness of the negative electrode material film is about 60-100μm.

[0085] As an optional embodiment of the technical solution of the present invention, in step (e), the negative electrode material film and the current collector (e.g., copper foil) enter the bonding roller together. Under the squeezing action of the bonding roller, the negative electrode material film is bonded to the surface of the current collector to obtain a negative electrode sheet with a smooth surface and no wrinkles, a thickness of about 60-110 μm (e.g., 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc.), and an areal density of about 80-180 g / m³. 2 (e.g. 80g / m 2 84g / m 2 90g / m 2 100g / m 2 110g / m 2 120g / m 2 130g / m 2 140g / m 2 150g / m 2 160g / m 2 170g / m 2 Or 180g / m 2 wait).

[0086] According to a third aspect of the present invention, an all-solid-state battery is provided, comprising a positive electrode, a solid electrolyte layer and a negative electrode, wherein the positive electrode and the negative electrode are stacked sequentially, and the solid electrolyte layer is disposed between two adjacent positive electrode and negative electrode.

[0087] The negative electrode sheet is the all-solid-state battery negative electrode sheet provided in the first aspect of the present invention or the all-solid-state battery negative electrode sheet prepared by the preparation method provided in the second aspect of the present invention;

[0088] The solid electrolyte layer includes inorganic ferroelectric II, piezoelectric polymer II, and sulfide electrolyte;

[0089] Among them, inorganic ferroelectric material II includes at least one of barium titanate, lead zirconate titanate, lithium niobate or bismuth layered structure compound;

[0090] Piezoelectric polymer II includes at least one of polyvinylidene fluoride, polyvinylidene fluoride, trifluoroethylene-polyvinylidene fluoride copolymer, polyethylene terephthalate, polylactic acid, or aromatic polyurea.

[0091] The all-solid-state battery provided by this invention simultaneously introduces inorganic ferroelectric materials (inorganic ferroelectric material I and inorganic ferroelectric material II) and piezoelectric polymers (piezoelectric polymer I and piezoelectric polymer II) into the negative electrode and solid electrolyte layer. Utilizing the system's own expansion stress, the inorganic materials and polymers spontaneously polarize under the influence of an external voltage, generating an electric field. This facilitates the acceleration of lithium migration at the interface and inside the negative electrode. The polymer acts as a binder and ion transport carrier, adapting to the intrinsic volume changes of the material. During discharge, as the electrode volume shrinks, the piezoelectric field gradually weakens and eventually disappears. This process is equivalent to adding periodic ion pumps inside the electrode and at the interface, thereby reducing the overall impedance of the solid-state battery during charging and improving cycle life and rate performance.

[0092] Furthermore, the solid electrolyte layer also employs inorganic ferroelectrics and piezoelectric polymers, resulting in better compatibility with the negative electrode. The generated piezoelectric field is enhanced in the same direction as the negative electrode, which is more conducive to the migration of lithium ions at the interface between the electrolyte layer and the negative electrode. If the electrolyte layer does not contain inorganic ferroelectrics and piezoelectric polymers, the electrolyte layer will not generate a local unidirectional electric field during charging. Lithium ions will transport slowly at the interface, while the negative electrode will transport quickly, easily forming a space charge layer (lithium-rich region and lithium-poor region), increasing transmission impedance, and hindering the improvement of the cell's charging rate performance and cycle performance.

[0093] As an optional embodiment of the technical solution of the present invention, the mass ratio of inorganic ferroelectric II, piezoelectric polymer II, and sulfide electrolyte in the solid electrolyte layer is (5-10):(5-10):(80-95). Typical but non-limiting mass ratios are 5:5:90, 5:5:85, 5:5:80, 8:5:90, 8:5:85, 8:5:80, 10:5:90, 10:5:85, 10:5:80, 5:8:87, 5:10:85, 8:10:82, 10:10:80, etc. The mass proportion of inorganic ferroelectric II in the solid electrolyte layer should not be too large, otherwise it may lead to an increase in the internal resistance of the system and a decrease in the intrinsic ionic conductivity of the sulfide electrolyte. The mass proportion of inorganic ferroelectric II in the solid electrolyte layer should not be too small, otherwise the piezoelectric effect may not be achieved. Similarly, the mass percentage of piezoelectric polymer II in the solid electrolyte layer should not be too large, otherwise it may lead to a decrease in the intrinsic ionic conductivity of the sulfide electrolyte. The mass percentage of piezoelectric polymer II in the solid electrolyte layer should also not be too small, otherwise it may lead to poor viscoelasticity and volume effect stress may cause the electrolyte layer to crack.

[0094] The specific types of inorganic ferroelectric materials in the negative electrode and the solid electrolyte layer can be the same or different. Similarly, the specific types of piezoelectric polymers in the negative electrode and the solid electrolyte layer can be the same or different.

[0095] As an optional embodiment of the technical solution of the present invention, the piezoelectric polymer II includes trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid, wherein the mass ratio of trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid is (1-5):(1-5), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 2:1, 3:1, 4:1 or 5:1, and more preferably 1:1.

[0096] As an optional embodiment of the technical solution of the present invention, the sulfide solid electrolyte includes at least one of LPSCl, LPSBr or LPSI.

[0097] As an optional embodiment of the technical solution of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on the surface of the positive electrode current collector;

[0098] The positive electrode material layer comprises: positive electrode active material, binder, conductive agent, and sulfide electrolyte. The mass ratio of the positive electrode active material, binder, conductive agent, and sulfide electrolyte is (60-90):(1-10):(1-10):(10-40), and typical but non-limiting mass ratios are 60:1:1:10, 60:5:1:10, 60:10:1:10, and 70:10:1. :10, 70:10:5:10, 70:10:10:10, 80:1:1:18, 80:5:5:10, 80:5:5:20, 80:10:10:30, 80:10:10:40, 90:1:1:10, 90:5:1:10, 90:5:5:20, 90:10:10:20 or 90:10:10:40, etc.

[0099] As an optional embodiment of the technical solution of the present invention, the conductive agent in the positive electrode material layer includes one or more of conductive carbon black, carbon nanotubes (CNTs), graphene or carbon fiber.

[0100] According to a fourth aspect of the present invention, a method for preparing an all-solid-state battery according to the third aspect of the present invention is provided, comprising the following steps:

[0101] S1. Disperse the mixture obtained by ball milling inorganic ferroelectric II, piezoelectric polymer II and sulfide electrolyte in a solvent to obtain a solid electrolyte slurry;

[0102] S2. Coat the surface of the negative electrode sheet with solid electrolyte slurry and dry it to obtain a negative electrode sheet with a solid electrolyte layer on the surface;

[0103] S3. The positive electrode and the negative electrode with a solid electrolyte layer formed on the surface are stacked together, and the solid electrolyte layer is located between two adjacent positive and negative electrodes. Then, hot pressing is performed to obtain an all-solid-state battery.

[0104] Existing fabrication methods typically involve layer-by-layer preparation (separately preparing the negative electrode and solid electrolyte layer) followed by assembly. This process is cumbersome, involves numerous variables, and makes it difficult to control the contact between the electrolyte layer and the negative electrode, resulting in poor electrical performance consistency and high interfacial impedance. To reduce interfacial impedance, this invention employs an integrated negative electrode and electrolyte layer approach to fabricate an all-solid-state battery. This method simplifies the assembly process, directly forming the solid electrolyte layer on the negative electrode, leading to better interfacial contact and improved electrical performance assembly yield.

[0105] As an optional embodiment of the technical solution of the present invention, in step S1, the ball milling time is 2-5 hours, such as 2 hours, 3 hours, 4 hours or 5 hours, and the ball milling speed is 800-1200 rpm, such as 800 rpm, 1000 rpm or 1200 rpm.

[0106] And / or, in step S1, dispersion is carried out with stirring, the dispersion temperature is 40-50℃, for example, 40℃, 42℃, 45℃, 48℃ or 50℃, the vacuum degree used during dispersion is ≥-90kPa, the rotation speed is 1200-1800rpm, for example, 1200rpm, 1500rpm or 1800rpm, the stirring time is 3-7h, for example, 3h, 5h or 7h, and the solid content of the solid electrolyte slurry is controlled to be 30-80%, for example, 30%, 40%, 50%, 60%, 70% or 80%.

[0107] As an optional embodiment of the technical solution of the present invention, in step S2, the drying is vacuum drying, the drying temperature is 70-90℃, for example 70℃, 75℃, 80℃, 85℃ or 90℃, and the drying time is 6-12h, for example 6h, 8h, 10h or 12h.

[0108] As an optional embodiment of the technical solution of the present invention, in step S3, the hot pressing temperature is 70-90℃, for example 70℃, 75℃, 80℃, 85℃ or 90℃, etc., 80℃, the hot pressing pressure is 800-1200KG, for example 800KG, 1000KG or 1200KG, and the holding time is 30-90s, for example 30s, 50s, 60s, 80s or 90s.

[0109] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. The raw material information used in each embodiment and comparative example is as follows: trifluoroethylene-polyvinylidene fluoride copolymer was purchased from Norian, with a molecular weight of 600,000; polylactic acid was purchased from Maclean, with a molecular weight of 300,000; polyacrylate was purchased from Maclean, with a molecular weight of 200,000; polyethylene oxide (PEO) was purchased from LyondellBasell, with a molecular weight of 400,000; and ceramic electrolyte (LATP) was purchased from Xinyuanbang, with a purity of 98.99%.

[0110] Example 1

[0111] This embodiment provides an all-solid-state negative electrode sheet, including a negative electrode current collector and a negative electrode material film disposed on the surface of the negative electrode current collector;

[0112] The negative electrode material membrane includes: negative electrode active material, binder, conductive carbon black, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte, with the above raw materials having a mass ratio of 65:2:2:3:3:25;

[0113] The negative electrode current collector is copper foil (6 μm thick); the negative electrode active material is silicon oxide (SiO) and graphite (VH) (mass ratio 8:2); the binder is PTFE; the conductive carbon black has a particle size of 30-50 nm; the inorganic ferroelectric material I is barium titanate, purchased from Aladdin, with a particle size of 1-20 μm; the piezoelectric polymer I includes trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid, with a mass ratio of 1:1; the sulfide solid electrolyte is LPSCl, with an average particle size of approximately 700 nm.

[0114] The preparation method of the all-solid-state negative electrode in this embodiment includes the following steps:

[0115] (a) A certain mass ratio of negative electrode active material, conductive carbon, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte are put into a dry mixer and mixed at 300-500 rpm for 30 min to obtain powder I.

[0116] (b) Add a certain mass of binder PTFE to powder I and mix and stir at 1000-1500 rpm for 30 minutes to obtain powder II;

[0117] Powder II was placed in a 60℃ oven and heated for 30 minutes to allow the powder to become fluffy, resulting in fluffy powder III (density 0.62 g / cm³). 3 );

[0118] (c) Powder III is placed in an air jet mill with an air pressure of 0.5 MPa. Under the impact of the air jet, powder III changes from a fluffy state to a stringy state, resulting in stringy powder IV (density 0.76 g / cm³). 3 );

[0119] (d) Powder IV is subjected to vertical roller pressing. Powder IV passes through the gap between two hot rollers from top to bottom and is formed under the extrusion of the two hot rollers. The pressure of vertical roller pressing is 5T, the temperature of vertical roller pressing is 110℃, and the width of the gap between the two hot rollers is 1μm.

[0120] After vertical roller pressing, powder IV is subjected to horizontal roller pressing. Powder IV passes through the gap between two horizontal rollers in the horizontal direction and is formed under the extrusion of the two horizontal rollers. The pressure of horizontal roller pressing is 5T, and the gap width between the two horizontal rollers is 1μm, resulting in a negative electrode material film with a film thickness of 105μm.

[0121] (e) The negative electrode film and copper foil are fed together into a bonding roller. Under the squeezing action of the bonding roller, the negative electrode film is bonded to the surface of the copper foil, resulting in a smooth and wrinkle-free all-solid-state negative electrode sheet with a thickness of up to 90 μm and an areal density of 140 g / cm³. 2 .

[0122] Example 2

[0123] This embodiment provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the mass ratio of negative electrode active material, binder, conductive carbon, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte in the negative electrode material film of Example 1 from 65:2:2:3:3:25 to 65:2:1:1:9:22, and also adjusting the mass ratio of each raw material in the preparation method accordingly, the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those in Example 1.

[0124] Example 3

[0125] This embodiment provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the type of inorganic ferroelectric material I in the negative electrode material film of Example 1 from barium titanate to an equal amount of lead zirconium titanate (purchased from Aladdin, with a particle size of 1-20 μm), the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those of Example 1.

[0126] Example 4

[0127] This embodiment provides an all-solid-state negative electrode sheet and its preparation method. Except that the type of piezoelectric polymer I in the negative electrode material film of Example 1 is changed from trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid to polylactic acid, and the mass ratio of piezoelectric polymer I in the negative electrode material film remains unchanged, the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those of Example 1.

[0128] Example 5

[0129] This embodiment provides an all-solid-state negative electrode sheet and its preparation method. Except for changing the type of piezoelectric polymer I in the negative electrode material film of Example 1 from trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid to trifluoroethylene-polyvinylidene fluoride copolymer, the mass ratio of piezoelectric polymer I remains unchanged. The rest of the all-solid-state negative electrode sheet structure, preparation method and process parameters are the same as those of Example 1.

[0130] Comparative Example 1

[0131] This comparative example provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the mass ratio of negative electrode active material, binder, conductive carbon, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte in the negative electrode material film of Example 1 from 65:2:2:3:3:25 to 65:2:2:2:6:0:25, and also adjusting the mass ratio of each raw material in the preparation method accordingly, the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those in Example 1.

[0132] Comparative Example 2

[0133] This comparative example provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the mass ratio of negative electrode active material, binder, conductive carbon, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte in the negative electrode material film of Example 1 from 65:2:2:3:3:25 to 65:2:2:2:0:6:25, and also adjusting the mass ratio of each raw material in the preparation method accordingly, the rest of the all-solid-state negative electrode sheet structure, preparation method and process parameters are the same as those in Example 1.

[0134] Comparative Example 3

[0135] This comparative example provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the mass ratio of negative electrode active material, binder, conductive carbon, inorganic ferroelectric material I, piezoelectric polymer I and sulfide electrolyte in the negative electrode material film of Example 1 from 65:2:2:3:3:25 to 65:5:5:0:0:25, and also adjusting the mass ratio of each raw material in the preparation method accordingly, the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those in Example 1.

[0136] Comparative Example 4

[0137] This comparative example provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the mass ratio of negative electrode active material, binder, conductive carbon, inorganic ferroelectric material I, piezoelectric polymer I, and sulfide electrolyte in the negative electrode material film of Example 1 from 65:2:2:3:3:25 to 55:2:2:2:2:13:3:25, the mass ratio of each raw material in the preparation method is also adjusted accordingly. The resulting all-solid-state negative electrode sheet has a thickness of 106 μm and an areal density of 165.5 g / cm³. 2 The structure, preparation method, and process parameters of the remaining all-solid-state anode sheets are the same as those in Example 1.

[0138] Comparative Example 5

[0139] This comparative example provides an all-solid-state negative electrode sheet and its preparation method. Except for adjusting the inorganic ferroelectric material I barium titanate in the negative electrode material film of Example 1 to an equal amount of potassium dihydrogen phosphate, the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those of Example 1.

[0140] Comparative Example 6

[0141] This comparative example provides an all-solid-state negative electrode sheet and its preparation method. Except that the type of piezoelectric polymer I in the negative electrode material film of Example 1 is changed from trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid to polyacrylate, and the mass ratio of piezoelectric polymer I in the negative electrode material film remains unchanged, the structure, preparation method and process parameters of the all-solid-state negative electrode sheet are the same as those of Example 1.

[0142] Example 6

[0143] This embodiment provides an all-solid-state battery, including a positive electrode, a solid electrolyte layer and a negative electrode provided in Embodiment 1. The positive electrode and the negative electrode are stacked in sequence, and the solid electrolyte layer is disposed between two adjacent positive electrode and negative electrode.

[0144] The solid electrolyte layer comprises inorganic ferroelectric material II, piezoelectric polymer II, and sulfide electrolyte in a mass ratio of 10:10:80. Among them, inorganic ferroelectric material II is barium titanate, purchased from Aladdin, with a particle size of 1-20 μm; piezoelectric polymer II is trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid in a mass ratio of 1:1; and sulfide solid electrolyte is LPSCl with an average particle size of approximately 700 nm.

[0145] The preparation method of the all-solid-state battery in this embodiment includes the following steps:

[0146] S1. Place inorganic ferroelectric II, piezoelectric polymer II and sulfide electrolyte into a ball mill and ball mill for 3 hours at a speed of 1000 rpm to obtain mixture 1 (this step increases the stability of sulfide electrolyte during processing in the drying room).

[0147] Mixture 1 was dispersed in NMP and stirred in a constant temperature vacuum mixer at 45℃, vacuum degree -90Kpa, speed 1500rpm for 5h, with solid content controlled at 60%, to obtain solid electrolyte slurry A.

[0148] S2. The solid electrolyte slurry is coated on the surface of the negative electrode, with a scraper height of 150 μm;

[0149] The negative electrode sheet coated with solid electrolyte slurry was placed in a vacuum drying oven at 80°C and dried for 8 hours.

[0150] After drying, the negative electrode sheet is placed into a roller press and rolled to obtain a negative electrode sheet with a solid electrolyte layer on the surface (the total thickness of the negative electrode sheet with the solid electrolyte layer on the surface is controlled to be 30 μm greater than the thickness of the negative electrode sheet).

[0151] S3. NCM811, conductive agent CNT, sulfide electrolyte LPSCl, and binder PVDF are dispersed in NMP in a ratio of 70:3:25:2, then coated onto aluminum foil and dried to obtain a positive electrode sheet with an areal density of 520 g / m³. 2 The compacted density is 3.4 g / cm³. 3 The thickness is 152μm;

[0152] The positive electrode sheet and the negative electrode sheet with a solid electrolyte layer on the surface are cut into electrode sheets of 50mm×50mm and 54mm×54mm respectively, and then stacked into a 3AH stack (12 layers of positive electrode). The resulting bare cell is hot-pressed with the following process parameters: temperature of 80℃, pressure of 1000KG and holding time of 60s. Finally, the hot-pressed cell aluminum-plastic film is assembled and packaged to obtain an all-solid-state battery (thickness of about 3.5mm).

[0153] Example 7

[0154] This embodiment provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 is the same as the negative electrode provided in Example 2, the rest of the solid-state battery structure and preparation method are the same as in Example 6.

[0155] Example 8

[0156] This embodiment provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 is the same as the negative electrode provided in Example 3, the rest of the solid-state battery structure and preparation method are the same as in Example 6.

[0157] Example 9

[0158] This embodiment provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 is the same as the negative electrode provided in Example 4, the rest of the solid-state battery structure and preparation method are the same as in Example 6.

[0159] Example 10

[0160] This embodiment provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 is the same as the negative electrode provided in Example 5, the rest of the solid-state battery structure and preparation method are the same as in Example 6.

[0161] Example 11

[0162] This embodiment provides an all-solid-state battery and its preparation method. Except for adjusting the mass ratio of inorganic ferroelectric II, piezoelectric polymer II and sulfide electrolyte in the solid electrolyte layer of Example 6 from 10:10:80 to 5:5:90, the solid-state battery structure and preparation method are the same as in Example 6.

[0163] Example 12

[0164] This embodiment provides an all-solid-state battery and its preparation method. Except that the mass ratio of piezoelectric polymer II in the solid electrolyte layer of Example 6 remains unchanged, the mass ratio of trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid is replaced from 1:1 to 6:1. The rest of the solid-state battery structure and preparation method are the same as those in Example 6.

[0165] Comparative Example 7

[0166] This comparative example provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 is the same as the negative electrode provided in Comparative Example 1, the other solid-state battery structure and preparation method are the same as in Example 6.

[0167] Comparative Example 8

[0168] This comparative example provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 uses the negative electrode provided in Comparative Example 2, the other solid-state battery structures and preparation methods are the same as in Example 6.

[0169] Comparative Example 9

[0170] This comparative example provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 uses the negative electrode provided in Comparative Example 3, the solid-state battery structure and preparation method are the same as in Example 6.

[0171] Comparative Example 10

[0172] This comparative example provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 uses the negative electrode provided in Comparative Example 4, the solid-state battery structure and preparation method are the same as in Example 6.

[0173] Comparative Example 11

[0174] This comparative example provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 uses the negative electrode provided in Comparative Example 5, the solid-state battery structure and preparation method are the same as in Example 6.

[0175] Comparative Example 12

[0176] This comparative example provides an all-solid-state battery and its preparation method. Except that the negative electrode in Example 6 is the same as the negative electrode provided in Comparative Example 6, the other solid-state battery structures and preparation methods are the same as in Example 6.

[0177] Comparative Example 13

[0178] This comparative example provides an all-solid-state battery and its preparation method. Except for replacing the piezoelectric polymer II in the solid electrolyte layer of Example 6 with an equal mass ratio of polyethylene oxide (PEO) instead of trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid, the solid-state battery structure and preparation method are the same as in Example 6.

[0179] Comparative Example 14

[0180] This comparative example provides an all-solid-state battery and its preparation method. Except for replacing the inorganic ferroelectric II in the solid electrolyte layer of Example 6 with an equal mass ratio of ceramic electrolyte (LATP), the solid-state battery structure and preparation method are the same as in Example 6.

[0181] Comparative Example 15

[0182] This comparative example provides an all-solid-state battery and its preparation method. Except that the piezoelectric polymer II in the solid electrolyte layer of Comparative Example 9 is replaced by polyoxyethylene fluoride copolymer and polylactic acid in an equal mass ratio with polyethylene oxide (PEO) (i.e., the mass ratio of piezoelectric polymer II remains unchanged), and the inorganic ferroelectric material II is replaced by barium titanate in an equal mass ratio with ceramic electrolyte (LATP) (i.e., the mass ratio of inorganic ferroelectric material II remains unchanged), the rest of the solid-state battery structure and preparation method are the same as those of Comparative Example 9.

[0183] Comparative Example 16

[0184] This comparative example provides an all-solid-state battery and its preparation method. Except for adjusting the mass ratio of inorganic ferroelectric II, piezoelectric polymer II and sulfide electrolyte in the solid electrolyte layer of Example 6 from 10:10:80 to 0:20:80, the rest of the solid-state battery structure and preparation method are the same as those in Example 6.

[0185] To compare the technical effects of the above embodiments and comparative examples, the following experimental examples are provided.

[0186] The electrochemical performance of the all-solid-state batteries prepared in the examples and comparative examples was tested, as follows:

[0187] Cyclic test: charging rate 2C, discharging rate 0.33C, voltage 2.5V-4.25V, charging method is constant current and constant voltage, cut-off current 0.05C, cycling until decay to 80% of the initial capacity, the cycle life is recorded as E (unit of revolution);

[0188] Charging rate test: Charging rates 1C, 2C, 3C, 4C. First, charge and discharge at 0.33C for one cycle, and record the discharge capacity as C0. Program: 1C0 constant current and constant voltage charging to 4.25V, cutoff current 0.05C0, then discharge at 0.33C to 2.5V. The charging constant current ratio (this is the test output data, which is the ratio of the capacity charged by constant current to the total charging capacity (constant current charging capacity + constant voltage charging capacity)) is recorded as F1. Repeat this test until 4C0 is completed and then stop. The charging constant current ratios are recorded as F1, F2, F3, and F4.

[0189] The test results are shown in Table 1.

[0190] Table 1

[0191]

[0192] As can be seen from the data in Table 1, compared with the comparative example, the all-solid-state batteries prepared in each embodiment of the present invention have a longer cycle life and better rate performance, indicating that the technical solution provided by the present invention can achieve the expected results.

[0193] Specifically, comparing Examples 6, 7-8, and 11-12, it is shown that when the specific types of inorganic ferroelectric material I and piezoelectric polymer I materials defined in this invention are used together, the effect on the negative electrode side is more obvious.

[0194] Comparing Examples 6, 13-14, and 16, it is evident that using a combination of two materials—a specific type of inorganic ferroelectric material II and a piezoelectric polymer II—at the interface, as defined in this invention, yields the best results.

[0195] Comparing Example 6 with Comparative Example 10, it is shown that when the proportion of inorganic ferroelectric materials is too large, the electronic conductivity of the system is significantly reduced.

[0196] The above description is merely 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 shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A negative electrode sheet for an all-solid-state battery, characterized in that, It includes a negative electrode current collector and a negative electrode material film disposed on the surface of the negative electrode current collector; The negative electrode material membrane includes: a negative electrode active material, a binder, a conductive agent, an inorganic ferroelectric material I, a piezoelectric polymer I, and a sulfide solid electrolyte; The inorganic ferroelectric material I includes at least one of barium titanate, lead zirconate titanate, lithium niobate, or bismuth layered structure compound. The piezoelectric polymer I is composed of trifluoroethylene-polyvinylidene fluoride copolymer and polylactic acid, wherein the mass ratio of trifluoroethylene-polyvinylidene fluoride copolymer to polylactic acid is (1-5):(1-5). The mass ratio of the negative electrode active material, binder, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I and sulfide solid electrolyte is (50-90): (2-10): (1-10): (1-10): (1-10): (10-30).

2. The all-solid-state battery negative electrode sheet according to claim 1, characterized in that, The particle size of the inorganic ferroelectric material I is 1-20 μm; And / or, the inorganic ferroelectric material I includes barium titanate.

3. The all-solid-state battery negative electrode sheet according to claim 1 or 2, characterized in that, The negative electrode active material includes one or more of silicon-carbon, silicon-oxygen, silicon, or graphite. And / or, the adhesive comprises one or more of PTFE, PEO, PVDF or SBR; And / or, the conductive agent includes at least one of conductive carbon black, carbon nanotubes, or graphene; And / or, the sulfide solid electrolyte includes at least one of LPSCl, LPSBr, or LPSI.

4. The method for preparing the all-solid-state battery negative electrode sheet according to any one of claims 1-3, characterized in that, Includes the following steps: (a) The negative electrode active material, conductive agent, inorganic ferroelectric material I, piezoelectric polymer I and sulfide solid electrolyte are mixed and stirred to obtain powder I; (b) Mix powder I and the binder to obtain powder II; Powder II is heated and kept at a constant temperature to obtain loose powder III; (c) Powder III is subjected to air jet milling to obtain powder IV in a filamentous state; (d) The powder IV is rolled to obtain a negative electrode material film; (e) The negative electrode material film and the negative electrode current collector are bonded and rolled together to obtain an all-solid-state negative electrode sheet.

5. The method for preparing the all-solid-state battery negative electrode sheet according to claim 4, characterized in that, In step (a), the mixing speed is 300-500 rpm and the mixing time is 20-60 min; And / or, in step (b), the mixing speed is 1000-1500 rpm, and the mixing time is 20-60 min; and / or, the heating and holding temperature is 40-70℃, and the heating and holding time is 20-40 min; and / or, the density of powder III is 0.5-0.8 g / cm³. 3 ; And / or, in step (c), the airflow pressure during air jet milling is 0.3-0.8 mPa; and / or, the density of powder IV is 0.5-0.8 g / cm³. 3 ; And / or, in step (d), roll forming includes vertical roll forming and horizontal roll forming, and the pressure of roll forming is 3-7T; And / or, in step (e), the thickness of the all-solid-state negative electrode is 60-110 μm, and the areal density is 80-180 g / m². 2 .

6. An all-solid-state battery, characterized in that, It includes a positive electrode, a solid electrolyte layer, and a negative electrode, wherein the positive electrode and the negative electrode are stacked sequentially, and the solid electrolyte layer is disposed between two adjacent positive electrode and negative electrode; The negative electrode sheet is the all-solid-state battery negative electrode sheet according to any one of claims 1-3 or the all-solid-state battery negative electrode sheet prepared by the preparation method according to claim 4 or 5; The solid electrolyte layer comprises inorganic ferroelectric II, piezoelectric polymer II, and sulfide solid electrolyte; The inorganic ferroelectric material II includes at least one of barium titanate, lead zirconate titanate, lithium niobate, or bismuth layered structure compounds. The piezoelectric polymer II includes at least one of polyvinylidene fluoride, trifluoroethylene-polyvinylidene fluoride copolymer, polyethylene terephthalate, polylactic acid, or aromatic polyurea.

7. The all-solid-state battery according to claim 6, characterized in that, The mass ratio of inorganic ferroelectric II, piezoelectric polymer II and sulfide solid electrolyte in the solid electrolyte layer is (5-10):(5-10):(80-95); And / or, the sulfide solid electrolyte includes at least one of LPSCl, LPSBr, or LPSI.

8. The all-solid-state battery according to claim 6 or 7, characterized in that, The positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on the surface of the positive current collector; The positive electrode material layer includes: positive electrode active material, binder, conductive agent and sulfide electrolyte, and the mass ratio of the positive electrode active material, binder and conductive agent and sulfide electrolyte is (60-90):(1-10):(1-10):(10-40).

9. The method for preparing an all-solid-state battery according to any one of claims 6-8, characterized in that, Includes the following steps: S1. Disperse the mixture obtained by ball milling inorganic ferroelectric II, piezoelectric polymer II and sulfide solid electrolyte in a solvent to obtain solid electrolyte slurry; S2. Coat the surface of the negative electrode sheet with a solid electrolyte slurry and dry it to obtain a negative electrode sheet with a solid electrolyte layer on the surface. S3. The positive electrode and the negative electrode with a solid electrolyte layer formed on the surface are stacked together, and the solid electrolyte layer is located between two adjacent positive and negative electrodes. Then, hot pressing is performed to obtain an all-solid-state battery.

10. The method for preparing an all-solid-state battery according to claim 9, characterized in that, In step S1, the ball milling time is 2-5 hours and the ball milling speed is 800-1200 rpm; And / or, in step S1, dispersion is carried out with stirring, the dispersion temperature is 40-50℃, the vacuum degree used during dispersion is ≥-90kPa, the rotation speed is 1200-1800rpm, the stirring time is 3-7h, and the solid content of the solid electrolyte slurry is controlled to be 30-80%; And / or, in step S2, the drying is vacuum drying, the drying temperature is 70-90℃, and the drying time is 6-12h; And / or, in step S3, the hot pressing temperature is 70-90℃, the hot pressing pressure is 800-1200 KG, and the holding time is 30-90s.

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