Negative plate as well as preparation method and application thereof

Abstract

The invention provides a negative plate as well as a preparation method and application thereof. The negative plate comprises a negative current collector and a negative active coating coated on at least one surface of the negative current collector, the negative electrode active coating comprises composite active particles, sulfide electrolyte and a conductive agent; wherein the composite active particle comprises a core and a coating layer, the core comprises a negative electrode active material, and the coating layer comprises an elastic composite electrolyte; the negative active material comprises a silicon element; the elastic composite electrolyte comprises a nano inorganic electrolyte and a polymer electrolyte. The coating layer of the elastic composite electrolyte is formed on the surface of the negative electrode active material, so that the volume expansion of silicon can be inhibited, the reduction decomposition of sulfide electrolyte is improved, the adhesive strength of the negative electrode active coating can be enhanced, and the lithium ion conduction performance of the negative electrode plate can be enhanced.

Description

Technical Field

[0001] This application belongs to the field of batteries, and in particular relates to a negative electrode sheet, its preparation method and application. Background Technology

[0002] Solid-state batteries, as a key development direction for next-generation battery technology, are characterized by the use of non-flammable or high-ignition-point solid electrolytes instead of traditional organic liquid electrolytes. This feature of solid-state batteries not only significantly improves the safety performance of the battery system but also simultaneously increases the system's energy density. This promises to meet the ever-increasing energy and safety requirements of future electric vehicles, energy storage systems, and other fields. Among various novel battery systems, solid-state batteries are the next-generation battery technology closest to industrialization, a consensus already reached by both industry and the scientific community.

[0003] Sulfide solid-state electrolytes, with their ionic conductivity comparable to liquid electrolytes, have become a focus of current research and application. They exhibit excellent thermal stability and a wide electrochemical stability window, demonstrating good safety performance, making them particularly suitable for applications requiring high power and wide temperature range performance. However, in constructing all-solid-state battery systems, silicon-based or lithium metal anodes are typically used to achieve the expected energy density advantage. Although lithium metal anodes possess extremely high theoretical capacity, their practical application is still constrained by cost, process complexity, and long-term safety. In contrast, silicon-based anode materials, with their higher specific capacity, relatively mature process foundation, and better overall cost-effectiveness, have become one of the more feasible technical routes for improving battery energy density at present.

[0004] However, the volume expansion of silicon can lead to particle breakage in silicon-based anode materials, causing repeated cracking of the anode sheet during charge and discharge. This can result in the active coating of the anode potentially separating from the current collector. Furthermore, when silicon comes into contact with sulfides, it exacerbates the reduction and decomposition of the sulfide electrolyte, which may gradually increase the impedance of the electrode and consume active lithium. Under the influence of these factors, the high specific capacity silicon-based anode may ultimately lead to a decline in the electrochemical performance of solid-state batteries. Summary of the Invention

[0005] In view of this, this application aims to provide a negative electrode sheet, its preparation method and application, so as to improve the electrochemical performance of all-solid-state batteries using silicon-containing negative electrodes.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: According to a first aspect of this application, a negative electrode sheet is provided, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active coating coated on at least one surface of the negative electrode current collector; the negative electrode active coating comprises composite active particles, a sulfide electrolyte and a conductive agent; wherein the composite active particles comprise a core and a coating layer, the core comprising a negative electrode active material and the coating layer comprising an elastic composite electrolyte; the negative electrode active material comprises silicon; the elastic composite electrolyte comprises a nano-inorganic electrolyte or a polymer electrolyte.

[0007] Preferably, the negative electrode active material includes at least one of nano-silicon, silicon carbide, silicon suboxide, and silicon dioxide; in the elastic composite electrolyte, the mass percentage of nano-inorganic electrolyte is 1% to 10%.

[0008] Preferably, the nano-inorganic electrolyte includes at least one of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum germanium phosphate (LAGP), and lithium zirconium oxide (Li2ZrO3); and / or, the particle size of the nano-inorganic electrolyte is 10 nm to 200 nm.

[0009] Preferably, the polymer electrolyte comprises a polymeric ion-conducting agent and a lithium salt, wherein the mass ratio of the polymeric ion-conducting agent to the lithium salt is (3~4):1; and / or, the polymeric ion-conducting agent comprises at least one of polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyphenylene ether, or polyazine; and / or, the lithium salt comprises at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate.

[0010] Preferably, the sulfide electrolyte includes Thio-LISICON, Li 10 GeP2S 12 Li 10 SnP2S 12 Li₂S-P₂S₅, Li 10 SiP2S 12 , Li2S-Si2S2, Li2S-B2S3, Li (7-a) PS (6-a) M a At least one of them; wherein, Li (7-a) PS (6-a) M a In this context, M includes at least one of Cl, Br, F, or I, and 0.1 ≤ a ≤ 5.9. Preferably, the negative electrode active coating comprises, by mass percentage, 50% to 85% negative electrode active material, 1% to 10% elastic composite electrolyte, 3% to 48.8% sulfide electrolyte, and 0.1% to 2% conductive agent.

[0011] According to a second aspect of this application, this application provides a method for preparing the negative electrode sheet as described above. The method includes the following steps: S1. After mixing and dissolving a polymer electrolyte with a solvent, a nano-inorganic electrolyte is added to obtain an elastic electrolyte premix; S2. Subsequently, the elastic electrolyte premix is ​​mixed into the negative electrode active material by pulse spraying to obtain a first slurry; S3. A sulfide electrolyte and a conductive agent are added to the first slurry for dispersion treatment to obtain a second slurry; S4. The second slurry is coated on at least one surface of the negative electrode current collector, and the negative electrode sheet is obtained after drying.

[0012] Preferably, in S1, the viscosity of the elastic electrolyte premix is ​​10 mPa·s to 100 mPa·s.

[0013] Preferably, in the pulse jet treatment, the pulse jet pressure is 2MPa~10MPa, the pulse jet time is 0.1 seconds~1 second, and the interval time is 1 second~30 seconds.

[0014] According to a third aspect of this application, this application provides a solid-state battery comprising a negative electrode, a positive electrode, and an electrolyte sheet, wherein the negative electrode is the aforementioned negative electrode or a negative electrode prepared according to the aforementioned method.

[0015] The technical solution of this application has at least the following beneficial effects: (1) This application forms a coating layer with both elasticity and strength on the surface of the silicon-containing negative electrode active material, which helps to stabilize the interface contact, inhibit the reduction and decomposition of sulfide electrolyte, and enhance the adhesion of the negative electrode active coating and improve the lithium-ion conduction performance of the negative electrode sheet. Therefore, the coating layer has the characteristics of bidirectional stability for both the negative electrode active material and the sulfide electrolyte.

[0016] (2) By forming an elastic composite electrolyte coating layer on the surface of the negative electrode active material, this application can suppress the volume expansion of silicon and improve the reduction and decomposition of sulfide electrolyte. At the same time, the coating layer can also improve the volume expansion and contraction of the negative electrode active material, thereby reducing the mechanical impact on the current collector, reducing the fatigue of the current collector and improving the interface breathing stability.

[0017] (3) The polymer electrolyte and nano-inorganic electrolyte in the coating layer can provide good flexibility and mechanical strength to the coating layer, and can also reduce the probability of direct contact between the negative electrode active material and the sulfide electrolyte particles, thereby reducing the occurrence of side reactions and avoiding the reduction and decomposition of sulfide particles in the negative electrode active coating under high SOC state.

[0018] (4) The molecular chains of the polymer electrolyte can form a three-dimensional network structure through physical entanglement, which can generate a mechanical locking effect on the material surface. This physical structure can enhance the adhesion strength between the coating layer and the negative electrode active material. This characteristic gives the negative electrode active coating provided in this application good adhesion strength without the need for additional binders. Therefore, as an optional solution, the negative electrode active coating of this application does not contain binders.

[0019] (5) The nanopore and micropore structures of the nano-inorganic electrolyte and polymer electrolyte can serve as lithium ion transport channels, and work synergistically with the sulfide electrolyte of the negative electrode active coating to enhance the lithium ion conduction performance of the negative electrode sheet.

[0020] (6) In the negative electrode sheet provided in this application, the lithium ion transport mechanism follows the free volume theory. In the negative electrode active coating provided in this application, the polymer component allows lithium ions to migrate through the organic chain segments in the non-crystalline region via the "jump" mechanism, while the inorganic phase particle component generates coordination between lithium ions through its surface functional groups, thereby reducing the transition energy barrier. The two work together as a bridge to transport lithium ions, which has better lithium ion transport convenience and electrochemical stability than the negative electrode active coating that separately coats the negative electrode active particles.

[0021] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0022] Figure 1 A schematic diagram of the composite active particles provided in this application; Figure 2 A schematic diagram of the negative electrode sheet provided in this application; Figure 3 This is a schematic diagram of the homogenization process of this application; Figure 4 This is a comparison chart of the capacity retention rate of Example 1 of this application and Comparative Examples 1-2 and 4 after 100 cycles; Figure 5 This is a comparison chart of the volume expansion rate of Example 1 of this application and Comparative Examples 1-2 and 4. Detailed Implementation

[0023] This application discloses a negative electrode sheet, its preparation method, and its application. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The methods and applications of this application have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application.

[0024] In the description of this application, the list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and 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, or 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 herein. Unless otherwise stated, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0026] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0027] 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.

[0028] In order to improve the electrochemical performance of all-solid-state batteries using silicon-containing anodes, this application provides an anode sheet, its preparation method, and its application.

[0029] According to a first aspect of this application, a negative electrode sheet is provided, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active coating coated on at least one surface of the negative electrode current collector; the negative electrode active coating comprises composite active particles, a sulfide electrolyte and a conductive agent; wherein the composite active particles comprise a core and a coating layer, the core comprising a negative electrode active material and the coating layer comprising an elastic composite electrolyte; the negative electrode active material comprises silicon; the elastic composite electrolyte comprises a nano-inorganic electrolyte or a polymer electrolyte.

[0030] In one embodiment of this application, the negative electrode active material includes at least one of nano-silicon, silicon carbide, silicon suboxide, and silicon dioxide; in the elastic composite electrolyte, the mass percentage of the nano-inorganic electrolyte is 1% to 10%. This application does not impose any special restrictions on the source of the aforementioned negative electrode active material; commercially available products well known to those skilled in the art can be used. For example, the mass percentage of the nano-inorganic electrolyte in the elastic composite electrolyte can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] In one embodiment of this application, the negative electrode active material further includes at least one of graphite, tin, or magnesium. This application does not impose any particular limitation on the source of the aforementioned graphite, tin, or magnesium; commercially available products well-known to those skilled in the art can be used.

[0032] In one embodiment of this application, the nano-inorganic electrolyte includes at least one of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum germanium phosphate (LAGP), and lithium zirconium oxide (Li₂ZrO₃); and / or, the particle size of the nano-inorganic electrolyte is 10 nm to 200 nm. This application does not impose any special restrictions on the source of the aforementioned nano-inorganic electrolyte; commercially available products well known to those skilled in the art can be used. Exemplarily, the particle size of the nano-inorganic electrolyte can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 180 nm, or 200 nm, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The functional groups on the surface of the nano-inorganic electrolyte particles can coordinate with lithium ions, thereby reducing the energy barrier for lithium ions to transition during their movement.

[0033] In one embodiment of this application, the chemical formula of the lithium aluminum titanium phosphate electrolyte (LATP) is Li. (1+x) Al x Ti (2-x) (PO4)3, where 0 < x < 1. For example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In one embodiment of this application, the chemical formula of lithium lanthanum zirconium oxide is Li7La3Zr2O. 12 .

[0035] In one embodiment of this application, the chemical formula of lithium lanthanum titanium oxide is Li7La3Zr2O. 12 .

[0036] In one embodiment of this application, lithium aluminum germanium phosphate (LAGP) has the chemical formula Li. (1+y) Al y Ge (2-y) (PO4)3, where 0 ≤ y ≤ 0.5. For example, y can be 0.1, 0.2, 0.3, 0.4 or 0.5, etc., but is not limited to the listed values; other unlisted values ​​within this range also apply.

[0037] In one embodiment of this application, the polymer electrolyte includes a polymeric ion-conducting agent and a lithium salt, wherein the mass ratio of the polymeric ion-conducting agent to the lithium salt is (3~4):1; and / or, the polymeric ion-conducting agent includes at least one of polyethylene glycol dimethacrylate (PEGDMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyphenylene ether (PPO), or polyphosphorazine (PPZ); and / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonylimide (LiFSI), lithium chloride (LiCl), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), or lithium perchlorate (LiClO4). This application does not impose any special restrictions on the source of the aforementioned polymeric ion-conducting agent and lithium salt; commercially available products well known to those skilled in the art can be used. For example, the mass ratio of the polymeric ion-conducting agent to the lithium salt can be 3:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, or 4:1, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. For polymeric electrolytes, the selection of the polymeric ion-conducting agent and / or the ratio of lithium salt can affect the flexibility, viscosity, and conductivity of the coating layer. In actual research and application, those skilled in the art tend to prioritize improving the electrochemical performance of the negative electrode, but this may sacrifice the viscosity or flexibility of the coating layer, thus affecting its long-term performance. This application improves the above problems by further optimizing the materials and / or ratio of the polymeric ion-conducting agent and lithium salt in the polymeric electrolyte.

[0038] In one embodiment of this application, the sulfide electrolyte includes Thio-LISICON, Li 10 GeP2S 12 Li 10 SnP2S 12 Li₂S-P₂S₅, Li 10SiP2S 12 , Li2S-Si2S2, Li2S-B2S3, Li (7-a) PS (6-a) M a At least one of them; wherein, Li (7-a) PS (6-a) M a In this context, M includes at least one of Cl, Br, F, or I, and 0.1 ≤ a ≤ 5.9. This application does not impose any special restrictions on the source of the aforementioned sulfide electrolyte; commercially available products well-known to those skilled in the art can be used. For example, in Li... (7-a) PS (6-a) M a In this context, 'a' can be 0.1, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 3, 4, 5, or 5.9, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] In one embodiment of this application, the negative electrode further includes a conductive agent, which includes at least one of a zero-dimensional conductive agent, a one-dimensional conductive agent, or a two-dimensional conductive agent. Based on their spatial geometric properties, conductive agents can be classified into zero-dimensional, one-dimensional, and two-dimensional types. Zero-dimensional conductive agents, as nanoscale point-like units, can effectively fill the gaps between active material particles; one-dimensional conductive agents have a high aspect ratio linear or fibrous structure, which can extend within the electrode and bridge long distances, thereby establishing a stable long-range conductive framework. Two-dimensional conductive agents, with their ultra-thin sheet-like morphology, can achieve large-area electronic contact.

[0040] In one embodiment of this application, the zero-dimensional conductive agent includes conductive carbon black (SP) and / or acetylene black (AB); and / or, the one-dimensional conductive agent includes carbon nanotubes (CNTs) and / or vapor-grown carbon fibers (VGCF); and / or, the two-dimensional conductive agent includes graphene. This application does not impose any special restrictions on the source of the above-mentioned conductive agents; commercially available products well known to those skilled in the art can be used.

[0041] In one embodiment of this application, the negative electrode active coating comprises, by weight percentage, 50% to 85% negative electrode active material, 1% to 10% elastic composite electrolyte, 3% to 48.8% sulfide electrolyte, and 0.1% to 2% conductive agent.

[0042] In one embodiment of this application, the areal capacity of the negative electrode is 3 mAh / cm². 2 ~15mAh / cm 2 More preferably, the areal capacity of the negative electrode is 4 mAh / cm². 2 ~8mAh / cm 2For example, the areal capacity of the negative electrode can be 3 mAh / cm². 2 4mAh / cm 2 5mAh / cm 2 6mAh / cm 2 7mAh / cm 2 8mAh / cm 2 9mAh / cm 2 10mAh / cm 2 11mAh / cm 2 12mAh / cm 2 13mAh / cm 2 14mAh / cm 2 or 15mAh / cm 2 This applies to, but not limited to, the listed values; other unlisted values ​​within this range also apply.

[0043] According to a second aspect of this application, this application provides a method for preparing the negative electrode sheet as described above. The method includes the following steps: S1. After mixing and dissolving a polymer electrolyte with a solvent, a nano-inorganic electrolyte is added to obtain an elastic electrolyte premix; S2. Subsequently, the elastic electrolyte premix is ​​mixed into the negative electrode active material by pulse spraying to obtain a first slurry; S3. A sulfide electrolyte and a conductive agent are added to the first slurry for dispersion treatment to obtain a second slurry; S4. The second slurry is coated on at least one surface of the negative electrode current collector, and the negative electrode sheet is obtained after drying.

[0044] This application uses pulse jetting to mix the elastic composite electrolyte with the negative electrode active material. As the mixing proceeds, the pulse jetting process causes the elastic composite electrolyte to gradually adhere to the surface of the negative electrode active material particles or fill the pores on the particle surface, forming a metastable coating layer.

[0045] The principle of the atomizing pulse jet equipment is as follows: the electronic control system precisely controls the nano-airflow formed by the mixing of nanoparticles and argon gas to spray the elastic electrolyte premix directly into the tank that is being homogenized through several micron nozzles. Combined with the real-time adjustment of the injection volume and pulse band by the electronic control unit, the elastic electrolyte premix is ​​uniformly distributed on the surface of the negative electrode active material.

[0046] Subsequently, by sequentially adding sulfide electrolyte and conductive agent, an elastic composite electrolyte is sandwiched between the larger-particle sulfide electrolyte and the negative electrode active material. At this point, this metastable coating layer transforms into a stable state due to being sandwiched between two large particles. Furthermore, with the addition of the conductive agent, the conductive agent and the elastic composite electrolyte without a coating layer disperse around the negative electrode active material and sulfide electrolyte, filling the pores of the negative electrode active material and sulfide electrolyte. After slurry coating, it acts as a stable ionic conductor at the interface between the active layer and the current collector, and also enhances interfacial adhesion, preventing the current collector side from reducing and decomposing the sulfide particles in the active layer under high SOC conditions. Because it combines elasticity and strength, it can also improve the impact of the expansion and contraction of the silicon-based or silicon-carbon active layer on the current collector, reduce the fatigue of the current collector, and improve the interfacial breathing stability. This coating layer ionic conductor must have bidirectional stability characteristics with both negative electrode particles and sulfide electrolyte, meet the low-voltage electrochemical stability of the negative electrode side, reduce the probability of direct contact between negative electrode particles and conductive electronic materials and sulfide electrolyte particles, and act as a bridge for lithium ion transfer. Therefore, the preparation method provided in this application can obtain a negative electrode sheet that balances elasticity and strength with higher ion conductivity without pre-coating the negative electrode active material. Thus, the preparation method provided in this application is convenient, low-cost, and also yields a negative electrode sheet with good electrochemical stability.

[0047] In one embodiment of this application, the solvent in the above preparation method includes at least one selected from dichloromethane, n-hexane, n-heptane, toluene, 2,4-dimethyl-3-pentanone, monochlorobenzene, xylene, toluene, isobutyl isobutyrate, anisole, cyclohexanone, 1,3,5-trimethylbenzene, n-decane, dodecane, and methylformamide. This application does not impose any special restrictions on the source of the above solvents; commercially available products well known to those skilled in the art can be used.

[0048] In one embodiment of this application, in S1, the viscosity of the elastic electrolyte premix is ​​10 mPa·s to 100 mPa·s. Exemplarily, the viscosity of the elastic electrolyte premix can be 10 mPa·s, 20 mPa·s, 30 mPa·s, 40 mPa·s, 50 mPa·s, 60 mPa·s, 70 mPa·s, 80 mPa·s, 90 mPa·s, or 100 mPa·s, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. Unlike previous technologies, the negative electrode sheet provided in this application can improve the spraying effect of the elastic electrolyte premix by optimizing and controlling its viscosity, thereby enhancing the structural stability of the composite active particles and improving the adhesion of the negative electrode active coating.

[0049] In one embodiment of this application, in step S2, the negative electrode active material is pre-dispersed by solvent-wetted ball milling for 15 to 120 minutes. More preferably, the dispersion time of solvent-wetted ball milling is 20 to 60 minutes.

[0050] In one embodiment of this application, during the pulse jet treatment, the pulse jet pressure is 2 MPa to 10 MPa, the pulse jet time is 0.1 seconds to 1 second, and the interval time is 1 second to 30 seconds. These are the time parameters for one cycle of jetting. In the pulse jet treatment, the above cycle needs to be repeated until the content of the elastic electrolyte in the formula is reached, at which point the pulse jet treatment is stopped.

[0051] In one embodiment of this application, the single inner diameter of the nozzle used in the pulse jet processing is 10μm to 30μm, and the atomizing nozzle is composed of several single nozzles, which are adjusted according to experimental requirements. The number of nozzles is generally 10 to 10,000.

[0052] In one embodiment of this application, the dispersion treatment includes one of stirring treatment and ball milling treatment.

[0053] In one embodiment of this application, in step S3, the dispersion treatment is ball milling, specifically comprising the following steps: ball milling the first slurry for 15 to 120 minutes, then adding a sulfide electrolyte and continuing ball milling for another 15 to 120 minutes, followed by adding a conductive agent and continuing ball milling for another 15 to 120 minutes to obtain a second slurry. More preferably, the ball milling time for the first slurry is 15 to 60 minutes; and / or, the ball milling time after adding the sulfide electrolyte is 20 to 60 minutes; and / or, the ball milling time after adding the conductive agent is 15 to 60 minutes.

[0054] In one embodiment of this application, the solid content of the second slurry is 10% to 70%.

[0055] In one embodiment of this application, in step S4, the drying temperature of the drying process is 60°C to 120°C, and the drying time is 5 hours to 24 hours.

[0056] According to a third aspect of this application, this application provides a solid-state battery, which includes a negative electrode, a positive electrode, and an electrolyte sheet, wherein the negative electrode is the aforementioned negative electrode or a negative electrode prepared according to the aforementioned method.

[0057] To further illustrate this application, the following experimental groups are described in detail. Unless otherwise specified, all raw materials used in the following experimental groups of this application are commercially available.

[0058] Experimental group 1 Example 1 1. Preparation of negative electrode sheet According to the mass percentage calculation, the raw materials required for preparing the negative electrode sheet in this embodiment are weighed according to the following formula: 70% negative electrode active material (silicon-carbon), 23% sulfide electrolyte (Li6PS5Cl), 2% conductive agent (vapor-grown carbon fiber, VGCF), and 5% elastic composite electrolyte. The elastic composite electrolyte includes polymer electrolyte and nano-inorganic electrolyte; and the mass percentage of nano-inorganic electrolyte in the elastic composite electrolyte is 5%.

[0059] S1. A polymer electrolyte was obtained by mixing a polymeric ion-conducting agent (polyvinylidene fluoride-hexafluoropropylene, PVDF-HFP) and a lithium salt (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI) at a mass ratio of 4:1. The polymer electrolyte obtained above was dissolved in xylene at 60°C for 12 hours, and then a nano-inorganic electrolyte (LATP, D50 of 30 nm) was added to obtain a viscosity of 50 mPa. s elastic electrolyte premix; S2. Weigh the negative electrode active material according to the above formula, then disperse the negative electrode active material by ball milling with xylene for 20 minutes, and then mix it into the elastic electrolyte premix prepared above by pulse jet treatment to obtain the first slurry; specifically, the pulse jet treatment is performed under the following conditions: pressure 5MPa, pulse jet time 0.5s, and interval time 1s, until the content of elastic composite ion conductor designed in the formula is reached and then the pulse jet is stopped. S3. After ball milling the first slurry for 15 minutes, add the formulated amount of sulfide electrolyte to the first slurry and continue ball milling for 30 minutes. Then add the formulated amount of conductive agent and continue ball milling for 30 minutes to obtain the second slurry. S4. A second slurry is coated onto the surface of the negative electrode current collector (coated with carbon copper foil), and after vacuum drying at 100°C for 8 hours and roll pressing, a negative electrode sheet is obtained. The designed areal capacity of the prepared negative electrode sheet is 4.5 mAh / cm². 2 .

[0060] 2. Solid-state battery fabrication Take 100mg Li 5.5 PS 4.5 Cl 1.5 The electrolyte sheet was prepared by placing it into a mold battery with a pore size of 10 mm and holding it at 300 MPa for 5 min; LiNbO3-coated NCM811 and Li 5.5 PS 4.5 Cl 1.5The conductive agent CNT is mixed in a mass ratio of 70:29:1 to obtain a mixed powder. 20mg of the mixed powder is placed on one side of the above-mentioned mold battery electrolyte sheet as a dry powder positive electrode sheet. The negative electrode sheet prepared above is punched to a diameter of 10mm and placed on the other side of the above-mentioned mold battery electrolyte sheet, thus completing the assembly to obtain a solid-state battery.

[0061] Example 2 This embodiment refers to the formula and method provided in Example 1 of Experimental Group 1 to prepare the negative electrode sheet and solid-state battery. The difference from Example 1 of Experimental Group 1 is that the mass ratio of nano-inorganic electrolyte in the elastic composite electrolyte is 1%. Apart from the above differences, the operation steps for preparing the negative electrode sheet and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0062] Example 3 This embodiment prepares the negative electrode and solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference from Example 1 of Experimental Group 1 is that the mass ratio of nano-inorganic electrolyte in the elastic composite electrolyte is 10%. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0063] Example 4 This embodiment prepares the negative electrode and solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference from Example 1 of Experimental Group 1 is that the mass ratio of nano-inorganic electrolyte in the elastic composite electrolyte is 20%. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0064] Example 5 This embodiment refers to the formulation and method provided in Example 1 of Experimental Group 1 to prepare the negative electrode and solid-state battery. The difference from Example 1 of Experimental Group 1 is that the particle size of lithium aluminum titanium phosphate (LATP) is 200nm. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0065] Example 6 This embodiment refers to the formulation and method provided in Example 1 of Experimental Group 1 to prepare the negative electrode and solid-state battery. The difference from Example 1 of Experimental Group 1 is that the particle size of lithium aluminum titanium phosphate (LATP) is 500nm. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0066] Example 7 This embodiment refers to the formulation and method provided in Example 1 of Experimental Group 1 to prepare the negative electrode and solid-state battery. The difference between this embodiment and Example 1 of Experimental Group 1 is that, in preparing the negative electrode, an equal mass fraction of lithium lanthanum zirconium oxide (Li7La3Zr2O) is used. 12 In addition to the differences mentioned above, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1, except that the negative electrode and solid-state battery are prepared by replacing lithium aluminum titanium phosphate (LATP).

[0067] Example 8 This embodiment prepares the negative electrode and solid-state battery according to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that, in preparing the negative electrode, an equal mass fraction of lithium lanthanum titanium oxide (Li) is used. 0.48 La 0.505 Except for the differences mentioned above, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1, except that TiO3 is used instead of lithium aluminum titanium phosphate (LATP).

[0068] Example 9 This embodiment refers to the formulation and method provided in Example 1 of Experimental Group 1 to prepare the negative electrode and solid-state battery. The difference between this embodiment and Example 1 of Experimental Group 1 is that lithium zirconium oxide (Li2ZrO3) is used instead of lithium aluminum titanium phosphate (LATP) in the preparation of the negative electrode. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0069] Example 10 This embodiment prepares the negative electrode and solid-state battery according to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that, in preparing the negative electrode, equal parts by mass of Li6.4La3Zr1.4Ta0.6O are used. 12 In this embodiment, except for the differences mentioned above, the operation steps for preparing the negative electrode and solid-state battery are strictly consistent with those in Example 1 of Experimental Group 1, replacing lithium aluminum titanium phosphate (LATP).

[0070] Comparative Example 1 This comparative example prepares a negative electrode and a solid-state battery using the formulation and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that an equal mass fraction of nano-inorganic electrolyte is used instead of polymer electrolyte (no polymer electrolyte is added) when preparing the negative electrode. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1.

[0071] Comparative Example 2 This comparative example prepares a negative electrode and a solid-state battery using the formulation and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that, in preparing the negative electrode, an equal mass fraction of polymer electrolyte is used instead of nano-inorganic electrolyte (no nano-inorganic electrolyte is added). Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1.

[0072] Comparative Example 3 This comparative example prepares a negative electrode and a solid-state battery using the formula and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that an equal mass fraction of nano-sized sulfide electrolyte Li6PS5Cl is used instead of nano-inorganic electrolyte (no nano-inorganic electrolyte is added) when preparing the negative electrode. Apart from the above differences, the operation steps for preparing the negative electrode and solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1.

[0073] Test Example 1 1. Test Object The negative electrode sheets and solid-state batteries prepared in Examples 1-10 and Comparative Examples 1-3 of Experimental Group 1 were used as test objects.

[0074] 2. Testing Methods (1) Cyclic performance test: The test pressure of the solid-state battery was controlled at 100MPa and the test temperature was controlled at 30℃. The battery was charged to the cutoff voltage of 4.25V with a constant current of 0.33C, and then discharged to the cutoff voltage of 2.2V with a constant current of 0.33C. The cycle test was repeated for 100 complete cycles. The discharge capacity of the first cycle was recorded as C1, and the discharge capacity of the 100th cycle was recorded as C2. 100 The capacity retention rate after 100 cycles can be obtained by the formula shown in equation (1).

[0075] Equation (1) (2) Electrode thickness expansion rate: The assembled solid-state battery is removed to obtain the negative electrode before charging. The cross section of the negative electrode before charging is treated by argon ion polishing and observed by SEM to obtain the thickness D1 of the negative electrode before charging. A parallel sample of the solid-state battery is taken and charged to 100% SOC at 0.1C under the conditions of 100MPa and 30℃. Then the charged solid-state battery is removed to obtain the charged negative electrode. The cross section of the charged negative electrode is treated by argon ion polishing and observed by SEM to obtain the thickness D2 of the charged negative electrode. The electrode thickness expansion rate can be obtained by the formula shown in (2).

[0076] Equation (2) 3. Test Results and Analysis The test results for this test example are shown in Table 1. By comparing the data of Example 1 with those of Comparative Examples 1-3, it can be seen that the negative electrode sheet provided in this application is designed with multiple considerations regarding the electrochemical stability of the sulfide electrolyte and the influence of the expansion and contraction of silicon-based particles on the chemical and physical stability of the negative electrode sheet. By coating the silicon-containing negative electrode active material with an elastic composite electrolyte of nano-inorganic electrolyte-polymer electrolyte, it is possible not only to significantly improve the capacity retention rate of the solid-state battery, but also to significantly reduce the expansion rate of the negative electrode sheet in the thickness direction.

[0077] Based on the data from Examples 1-10, it is evident that in the negative electrode provided in this application, the nano-inorganic electrolyte constitutes an effective channel for lithium-ion conduction. By further optimizing its mass content, particle size, and specific materials used in the coating layer, the ion conduction performance of the negative electrode can be further improved. This is because the functional groups on the surface of the inorganic phase particles can coordinate with lithium ions, thereby reducing the energy barrier for lithium ion transitions during movement, thus enabling the negative electrode to achieve more efficient ion transport.

[0078] Specifically, based on the data from Examples 1-4, it can be seen that in the elastic composite electrolyte, as the mass proportion of the nano-inorganic electrolyte increases, the thickness expansion rate of the negative electrode gradually increases, while the capacity retention rate of the solid-state battery using it shows a trend of first increasing and then decreasing. The above data demonstrates that when the mass proportion of the nano-inorganic electrolyte in the elastic composite electrolyte is between 1% and 10%, the lithium-ion conductivity of the negative electrode can be further improved, thus enabling the solid-state battery using it to maintain a good capacity retention rate while keeping the electrode expansion rate low. Furthermore, based on the data from Examples 1 and 5-6, it can be seen that the particle size of the nano-inorganic electrolyte may be related to the formation of a more uniform interfacial coating layer. When the particle size of the nano-inorganic electrolyte is between 10nm and 200nm, it is beneficial to improve interfacial stability, enhance ion conduction, and provide a certain buffering effect on volume changes, thereby contributing to a relatively high capacity retention rate and a relatively low electrode expansion rate. Furthermore, data from Examples 1 and 7-10 show that the functional groups on the surface of nano-inorganic electrolyte particles can coordinate with lithium ions, thereby further reducing the energy barrier for lithium ions to transition during movement and improving the capacity retention of solid-state batteries.

[0079] Table 1. Test results provided in Test Example 1

[0080] Experimental group 2 The embodiments in this experimental group prepared negative electrode sheets and solid-state batteries according to the formulation and method provided in Embodiment 1 of Experimental Group 1. The variables used in the polymer electrolyte, such as the polymer ion-conducting agent, lithium salt mass ratio, or materials, are shown in Table 2. Except for the differences mentioned above, the operational steps for preparing negative electrode sheets and solid-state batteries in each embodiment of this experimental group are strictly consistent with those in Embodiment 1 of Experimental Group 1. Furthermore, for clear comparison, the polymer electrolyte used in Embodiment 1 of Experimental Group 1 is included in Table 2. In Embodiment 13, the polymer ion-conducting agent used is polyphenylene ether (PPO).

[0081] Table 2. Variables involved in each embodiment of Experimental Group 2

[0082] Test Example 2 1. Test Object The negative electrode sheet and solid-state battery prepared in Example 1 of Experimental Group 1 and each example of Experimental Group 2 were used as test objects.

[0083] 2. Testing Methods Refer to the test method provided in Test Example 1.

[0084] 3. Test Results and Analysis The test results for Test Example 2 are shown in Table 3. For clear comparison, the data from Example 1 are included in Table 3. Compared to conventional solid-state batteries that introduce binders (such as NBR, SBR, PAA, PIB, SBS, HNBR, etc.) during the fabrication of the negative electrode, the negative electrode provided in this application does not require additional binders while still exhibiting good adhesion performance. This is because the polymer ion-conducting agent in the polymer electrolyte can form a three-dimensional network structure through physical entanglement, generating a mechanical locking effect on the material surface. This physical structure enhances the adhesion strength between the polymer and the negative electrode active material, therefore, the electrode does not require additional binders.

[0085] Data from Examples 1 and 11-13 show that the movement of organic chain segments in the amorphous region of the polymer ion-conducting agent not only affects the volume expansion and contraction capacity of the coating layer buffer active material, but also affects the lithium-ion transport efficiency.

[0086] Data from Examples 1 and 14-15 show that by changing the combination of the polymer ion-conducting agent and the lithium salt, the lithium-ion transport efficiency of the negative electrode can be further improved.

[0087] Furthermore, by comparing the data from Example 1 and Examples 16-18, it can be seen that this application can affect the cycle capacity retention rate of solid-state batteries by controlling the mass ratio between polymer ion-conducting agent and lithium salt.

[0088] Therefore, as can be seen from this test example, this application can further regulate the adhesion performance or flexibility of the coating layer by adjusting the mass ratio between the polymer ion-conducting agent and the lithium salt in the polymer electrolyte or the materials used, thereby further enhancing the cycle capacity retention rate of the solid-state battery.

[0089] Table 3. Test results provided in Test Example 2

[0090] Experimental group 3 Example 19 This embodiment prepares the negative electrode and solid-state battery according to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that the viscosity of the elastic electrolyte premix in step S1 when preparing the negative electrode is 10 mPa. Except for the differences mentioned above, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0091] Example 20 This embodiment refers to the formulation and method provided in Example 1 of Experimental Group 1 to prepare the negative electrode sheet and solid-state battery. The difference between this embodiment and Example 1 of Experimental Group 1 is that the viscosity of the elastic electrolyte premixed solution in step S1 when preparing the negative electrode sheet is 100 mPa. Except for the differences mentioned above, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0092] Example 21 This embodiment prepares a negative electrode and a solid-state battery using the formula and method provided in Example 1 of Experimental Group 1. The difference from Example 1 of Experimental Group 1 is that the viscosity of the elastic electrolyte premix in step S1 of preparing the negative electrode in this embodiment is 500 mPa. Except for the differences mentioned above, the operation steps for preparing the negative electrode and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0093] Example 22 This embodiment prepares the negative electrode sheet and solid-state battery according to the formula and method provided in Example 1 of Experimental Group 1. The difference from Example 1 of Experimental Group 1 is that this embodiment uses a drop-addition process to mix the elastic electrolyte premix into the negative electrode active material during the preparation of the negative electrode sheet. Apart from the above differences, the operation steps for preparing the negative electrode sheet and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1. Specifically, this embodiment prepares the negative electrode sheet according to the following steps: S1. Strictly follow the steps provided in Example 1 of Experimental Group 1; S2. Weigh the negative electrode active material according to the formula provided in Example 1 of Experimental Group 1, then disperse the negative electrode active material by ball milling with xylene for 20 minutes, and then add the elastic electrolyte premix solution prepared above by stirring while adding dropwise to obtain the first slurry; wherein, the dropping rate is 0.1 mL / min~2 mL / min; S3~S4 strictly follow the steps provided in Example 1 of Experimental Group 1.

[0094] Example 23 This embodiment prepares the negative electrode sheet and solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that the negative electrode active material is coated by solid-state method. Apart from the above differences, the operation steps for preparing the negative electrode sheet and solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0095] Specifically, the negative electrode sheet is prepared according to the following steps in this embodiment: First, according to the formula provided in Example 1 of Experimental Group 1, the negative electrode active material, part of the conductive agent, and the elastic composite electrolyte are weighed, and a coating layer is formed on the surface of the negative electrode active material by ball milling to obtain composite active particles; then, the composite active particles, the remaining conductive agent, the sulfide electrolyte, and xylene are mixed by ball milling to obtain a negative electrode slurry; the negative electrode slurry is coated on the surface of the negative electrode current collector (coated copper foil), and after vacuum drying at 100°C for 8 hours and roll pressing, a negative electrode sheet is obtained.

[0096] Comparative Example 4 This comparative example prepares a negative electrode sheet and a solid-state battery using the formula and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that this comparative example uses a pre-coating method during the preparation of the negative electrode sheet, ensuring that the composite active particles are structured with only nano-inorganic electrolyte coating the negative electrode active material. Apart from the above differences, the operational steps for preparing the negative electrode sheet and solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1. Specifically, this comparative example prepares the negative electrode sheet according to the following method.

[0097] The comparative example uses the following formula to weigh the raw materials required for preparing the negative electrode sheet: 70% negative electrode active material (silicon-carbon), 24% sulfide electrolyte (Li6PS5Cl), 1% conductive agent (vapor-grown carbon fiber, VGCF), 4.75% PVDF-HFP, and 0.25% LATP.

[0098] The negative electrode sheet in this comparative example was prepared according to the following steps: First, silicon carbon and LATP were mixed by ball milling according to the above formula to obtain composite active particles of LATP-coated silicon carbon particles. Then, the composite active particles, sulfide electrolyte, conductive agent and PVDF-HFP (binder) were mixed evenly according to the above formula to obtain a negative electrode slurry. The negative electrode slurry was coated on the surface of the negative electrode current collector (coated copper foil), and after vacuum drying at 100°C for 8 hours and roll pressing, a negative electrode sheet was obtained.

[0099] Test Example 3 1. Test Object The negative electrode sheets and solid-state batteries prepared by Example 1 and Comparative Example 1 of Experimental Group 1, and each example and comparative example of Experimental Group 3 were used as test objects.

[0100] 2. Testing Methods Refer to the test method provided in Test Example 1.

[0101] 3. Test Results and Analysis The test results for Test Example 3 are shown in Table 4. For clear comparison, data from Example 1 and Comparative Example 1 are included in Table 4.

[0102] Based on the data from Examples 1 and 19-21, it is known that the negative electrode sheet provided in this application can improve the spraying effect of the elastic electrolyte premix by controlling the viscosity of the elastic electrolyte premix, thereby improving the structural stability of the composite active particles and the adhesion of the negative electrode active coating. Specifically, as the viscosity of the elastic electrolyte premix increases, the capacity retention rate shows a fluctuating trend of first increasing and then decreasing, while the expansion rate shows a decreasing trend.

[0103] Furthermore, based on the data from Examples 1, 22-23, and Comparative Example 4, it is evident that the anode preparation method provided in this application combines micro-coating with electrode design and homogenization processes. Compared to traditional anode preparation methods that only pre-coat a single anode particle, the bidirectional mixing and coating method provided in this application results in fewer side reactions during electrode cycling, lower solid-solid contact loss due to expansion and contraction impacts, and more stable long-term cycling performance. Therefore, the anode preparation method provided in this application not only simplifies the existing sulfide anode manufacturing process but also improves the optimization efficiency of sulfides at the electrode level.

[0104] In summary, based on the data from test examples 1-3, the negative electrode provided in this application considers the electrochemical stability of the sulfide electrolyte and the effects of the expansion and contraction of silicon-based particles on the chemical and physical stability of the electrode at both the material and electrode levels. This results in a lower electrode expansion rate compared to negative electrode prepared by simply coating negative electrode particles in advance, and enables solid-state batteries using it to have better capacity retention.

[0105] Table 4. Test results provided in Test Example 3

[0106] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A negative electrode sheet, characterized in that, The negative electrode sheet includes a negative electrode current collector and a negative electrode active coating coated on at least one surface of the negative electrode current collector; The negative electrode active coating comprises composite active particles, sulfide electrolyte, and conductive agent; The composite active particles include a core and a coating layer, wherein the core includes a negative electrode active material and the coating layer includes an elastic composite electrolyte; The negative electrode active material includes silicon. The elastic composite electrolyte includes nano-inorganic electrolytes and polymer electrolytes.

2. The negative electrode sheet as described in claim 1, characterized in that, The negative electrode active material includes at least one of nano-silicon, silicon carbide, silicon suboxide, and silicon dioxide; in the elastic composite electrolyte, the mass percentage of the nano-inorganic electrolyte is 1% to 10%.

3. The negative electrode sheet as described in claim 1, characterized in that, The nano-inorganic electrolyte includes at least one of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum titanium oxide, and lithium germanium aluminum phosphate. And / or, the particle size of the nano-inorganic electrolyte is 10nm~200nm.

4. The negative electrode sheet as described in claim 1, characterized in that, The polymer electrolyte comprises a polymer ion-conducting agent and a lithium salt, wherein the mass ratio of the polymer ion-conducting agent to the lithium salt is (3~4):1; And / or, the polymeric ion-conducting agent includes at least one of polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyphenylene ether, or polyazine; And / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate.

5. The negative electrode sheet as described in claim 1, characterized in that, The sulfide electrolyte includes Thio-LISICON, Li 10 GeP2S 12 Li 10 SnP2S 12 Li₂S-P₂S₅, Li 10 SiP2S 12 , Li2S-Si2S2, Li2S-B2S3, Li (7-a) PS (6-a) M a At least one of them; wherein, Li (7-a) PS (6-a) M a In this context, M includes at least one of Cl, Br, F, or I, and 0.1 ≤ a ≤ 5.

9.

6. The negative electrode sheet according to any one of claims 1 to 5, characterized in that, The negative electrode active coating comprises, by weight percentage, 50% to 85% of the negative electrode active material, 1% to 10% of the elastic composite electrolyte, 3% to 48.8% of the sulfide electrolyte, and 0.1% to 2% of the conductive agent.

7. A method for preparing a negative electrode sheet as described in any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: S1. After dissolving the polymer electrolyte in a solvent, add the nano-inorganic electrolyte to obtain an elastic electrolyte premix; S2. Subsequently, the elastic electrolyte premix is ​​mixed into the negative electrode active material by pulse jet treatment to obtain the first slurry; S3. The sulfide electrolyte and the conductive agent are added to the first slurry for dispersion treatment to obtain the second slurry; S4. The second slurry is coated on at least one surface of the negative electrode current collector, and the negative electrode sheet is obtained after drying.

8. The method as described in claim 7, characterized in that, In S1, the viscosity of the elastic electrolyte premix is ​​10 mPa·s to 100 mPa·s.

9. The method as described in claim 7, characterized in that, In the pulse jet treatment, the pulse jet pressure is 2MPa~10MPa, the pulse jet time is 0.1 seconds~1 second, and the interval time is 1 second~30 seconds.

10. A solid-state battery, the solid-state battery comprising a negative electrode, a positive electrode, and an electrolyte, characterized in that, The negative electrode sheet is the negative electrode sheet according to any one of claims 1 to 6, or the negative electrode sheet prepared by the method according to any one of claims 7 to 9.

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