A negative electrode sheet for a solid-state battery and a method for manufacturing the same, and a solid-state battery

Abstract

This invention provides a negative electrode sheet for a solid-state battery, a method for preparing the same, and a solid-state battery. The negative electrode sheet is a solid-state composite negative electrode sheet, comprising negative electrode active material particles and electrolyte particles. The particle size of the negative electrode active material particles and the particle size of the electrolyte particles conform to the following condition: 9 ≤ λ (D50). 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 The value of λ is ≤12, where λ is the error control factor, and 1≤λ≤1.2. This invention, through precise control of the size of anode material particles and electrolyte particles, clarifies the quantitative principle of particle size matching and determines the particle matching boundary. This enables a comprehensive improvement in electrode ionic conductivity, capacity, rate capability, and cycle stability. It proposes a quantifiable standard, which can accurately solve the core contradiction in all-solid-state composite anode design (the synergy between interface contact and ion transport), and promote the industrialization of solid-state batteries.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more specifically, to a negative electrode sheet for solid-state batteries, a method for preparing the same, and solid-state batteries. Background Technology

[0002] In recent years, lithium-ion batteries have achieved significant technological breakthroughs in areas such as range, fast charging, and safety, sparking a global surge in technological development and industrialization. The high safety of lithium-ion batteries has garnered increasing attention from users and businesses. In liquid systems, lithium iron phosphate batteries, thanks to their high safety, have seen their market share rise year by year, gradually taking a leading position. However, they still suffer from drawbacks such as relatively low energy density and poor low-temperature performance, failing to fully meet customer needs.

[0003] Solid-state batteries, as a key future development direction, are expected to become star products in the lithium-ion battery market due to their high safety and high energy density. The development of solid-state batteries has received continuous attention from research institutions worldwide. The high ionic conductivity of sulfide electrolytes has made sulfide-based solid-state batteries one of the mainstream research routes. However, the main bottleneck of solid-state batteries is the solid-solid interface problem, which cannot achieve the solid-liquid contact state of liquid batteries. Improving the interfacial and bulk transport capabilities within the electrode is a key research focus and challenge. Liquid lithium-ion batteries often have electrolytes with good fluidity, capable of filling any interface and acting as a bridge for ion transport. However, in solid-state battery systems, the electrolyte is often in the form of solid particles, resulting in a solid-solid contact. This significantly reduces interfacial and bulk ion transport, hindering the industrialization of solid-state batteries. Therefore, developing and designing solid-state negative electrode sheets to improve the solid-solid interface and enhance ion transport capabilities is one of the bottlenecks in the industrialization of solid-state batteries.

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

[0005] The purpose of this invention is to address the shortcomings of existing technologies and the technical characteristics and requirements of all-solid-state batteries by providing a negative electrode sheet for solid-state batteries, its preparation method, and a solid-state battery. By precisely controlling the size of the negative electrode material particles and electrolyte particles, clarifying the quantitative principle of particle size matching, and determining the particle matching boundary, without introducing new materials or complex modifications, the overall improvement of electrode ionic conductivity, capacity, rate capability, and cycle stability can be achieved simply by selecting the matching of active material and electrolyte particle sizes. A quantifiable standard is proposed, which can accurately solve the core contradiction in all-solid-state composite negative electrode design (the synergy between interface contact and ion transport), thus promoting the industrialization of solid-state batteries.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A negative electrode sheet for solid-state batteries, wherein the negative electrode sheet is a solid-state composite negative electrode sheet comprising negative electrode active material particles and electrolyte particles, wherein the particle size of the negative electrode active material particles and the particle size of the electrolyte particles conform to the following condition: 9 ≤ λ (D50) 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 )≤12, where λ is the error control factor, 1≤λ≤1.2.

[0007] Furthermore, the negative electrode sheet comprises the following components by mass fraction: 50-90 wt% negative electrode active material particles, 5-40 wt% electrolyte particles, 0.5-3 wt% binder, and 1-8 wt% conductive agent.

[0008] Furthermore, the negative electrode sheet comprises the following components by mass fraction: 60-80 wt% negative electrode active material particles, 15-30 wt% electrolyte particles, 0.5-3 wt% binder, and 1-8 wt% conductive agent.

[0009] Furthermore, the negative electrode active material is at least one of micron-sized silicon, nano-sized silicon, CVD silicon-carbon, artificial graphite, and natural graphite.

[0010] Furthermore, the electrolyte includes at least one of sulfide electrolytes, halide electrolytes, and oxide electrolytes.

[0011] Furthermore, the adhesive is at least one of styrene-ethylene-butadiene-styrene copolymer, hydrogenated nitrile rubber, polyethylene, polypropylene, polyisobutylene, amorphous polyalphaolefin, and acrylate rubber.

[0012] Furthermore, the conductive agent is at least one of VGCF, CNT, and graphene.

[0013] Furthermore, the sulfide electrolyte is Li6PS5Cl, Li6PS5Br, or Li 5.5 PS 4.5 Cl 0.7 Br 0.8 Li7PS6, Li7P3S 11 Li6PS5Cl 0.5 Br 0.5 Li 10 GeP2S 12 Li 10 SnP2S 12 Li 3.25 Ge0.25 P 0.75 At least one of S4.

[0014] The above-mentioned method for preparing the negative electrode sheet for solid-state batteries includes the following steps: Step S1: The electrolyte is ball-milled to obtain electrolyte particles of the target particle size, denoted as material E1; Step S2: Take the negative electrode active material particles of the target particle size according to the ratio and mix them evenly with the material E1 particles to obtain the mixed material E2. Step S3: Add the adhesive to the solvent according to the ratio, and stir mechanically until the solution is clear. Record this as solution F1. Step S4: Add the conductive agent to solution F1 according to the ratio, and stir mechanically to obtain mixed solution F2; Step S5: Homogenize the mixed solution F2 with the mixed material E2 to obtain the negative electrode slurry E3; Step S6: Coat the negative electrode slurry E3 onto the surface of the current collector and dry it to obtain the negative electrode sheet for solid-state batteries.

[0015] Furthermore, the ball milling process in step S1 is as follows: the ball-to-material ratio is 10:1-2:1, the ball milling speed is 300-700 rpm, and the ball milling time is 0.5h-5h.

[0016] Furthermore, the powder mixing process in step S2 is as follows: the mixing speed is 300-1100 rpm, and the mixing time is 0.5h-2h.

[0017] Furthermore, in step S3, the mechanical stirring speed is 800-1000 rpm.

[0018] Further, the solvent mentioned in step S3 is at least one of toluene, n-decane, n-undecane, n-dodecane, n-tetrazane, n-tetradecane, n-pentadecane, 1-decene, 1-undecene, 1-dodecene, 1-tetrazene, 1-tetradecene, butyl butyrate, isobutyl butyrate, n-pentyl butyrate, n-pentyl ether, n-hexyl ether, n-heptyl ether, n-octyl ether, and diphenyl ether.

[0019] Furthermore, in step S4, the mechanical stirring speed is 800-1200 rpm, and the mechanical stirring time is 1-3 hours.

[0020] Furthermore, in step S5, a planetary mixer is used for homogenization, with a revolution speed of 20-50 rpm, a rotation speed of 1000-5000 rpm, and a homogenization time of 0.5h-2h.

[0021] Furthermore, in step S6, the drying temperature is 80-110℃, and the drying is carried out under vacuum or inert atmosphere.

[0022] A solid-state battery uses the negative electrode sheet for solid-state batteries described above or the negative electrode sheet prepared by the above preparation method. The positive electrode material used in the solid-state battery is at least one of lithium manganese oxide, lithium iron phosphate, lithium cobalt oxide, nickel-cobalt-manganese ternary materials, and elemental sulfur.

[0023] Furthermore, the nickel-cobalt-manganese ternary material includes LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention relates to a negative electrode sheet for solid-state batteries and its preparation method, as well as solid-state batteries. Without introducing new materials or complex modifications, it constructs a hierarchical ion transport structure inside the negative electrode sheet, thereby improving its interfacial contact transport and bulk ion transport, solving the solid-solid contact bottleneck problem of solid-state batteries, and achieving performance improvements in capacity, cycle life, rate capability, and other aspects of solid-state batteries.

[0025] 2. The present invention relates to the negative electrode sheet for solid-state batteries and its preparation method. Solid-state batteries are not simply a matter of mixing active materials and solid electrolytes in terms of size, but rather possess a specific design principle: 9≤λ(D50) 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 )≤12, where λ is the error control factor (1≤λ≤1.2). This design principle can specifically guide the hierarchical structure design of solid-state negative electrode sheets. It can fill the gaps between negative electrode material particles with small particles, improve interfacial contact, reduce the "island-like" distribution of active main materials, improve the continuity of bulk phase transport, and achieve precise control of electrolyte particle size. It provides quantitative guidance for the hierarchical structure engineering of negative electrode sheets, realizes the optimal size matching relationship, achieves synergistic optimization of interfacial contact and ion transport efficiency, and promotes the all-solid-state battery from the laboratory to industrialization.

[0026] 3. This invention can prepare solid-state anode sheets with high ion transport capabilities. The key lies in the efficient construction of the ion conduction network in the composite anode. The first principle of its development is to build a hierarchical structure, rather than simply a matter of matching the sizes of anode particles and electrolyte particles. This invention, through precise control of the size of anode material particles and electrolyte particles, clarifies the quantitative principle of particle size matching and determines the particle matching boundary. Without introducing new materials or complex modifications, it can achieve a comprehensive improvement in capacity, rate capability, and cycle stability simply by selecting the matching size of the active material and electrolyte particles. This technology proposes a quantifiable standard, which can accurately solve the core contradiction in the design of all-solid-state composite anodes (the synergy between interface contact and ion transport), thus promoting the industrialization of solid-state batteries. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is an electron microscope image of the negative electrode sheet for solid-state batteries prepared in Example 1 of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0030] In actual development, both excessively large and excessively small electrolyte particle sizes can lead to battery performance degradation and make it impossible to guarantee the consistency between the quality of the negative electrode and battery performance. For example, large electrolyte particles cannot fill the gaps between the negative electrode active materials, resulting in insufficient interfacial contact and "island-like" breakage of ion transport. However, if the particles are too small, they may increase interfacial impedance and reduce ion conduction efficiency. There is a lack of clear guiding principles for electrode design.

[0031] This invention provides a negative electrode sheet for solid-state batteries. The negative electrode sheet is a solid-state composite negative electrode sheet, comprising negative electrode active material particles and electrolyte particles. The particle size of the negative electrode active material particles and the particle size of the electrolyte particles conform to the following condition: 9 ≤ λ (D50). 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 )≤12, where D50 负极 D90 is the particle size value corresponding to when the cumulative particle size distribution in the negative electrode active material reaches 50%. 负极 D50 is the particle size value corresponding to when the cumulative particle size distribution in the negative electrode active material reaches 90%. 电解质 D90 is the particle size value corresponding to when the cumulative particle size distribution in electrolyte particles reaches 50%. 电解质 It is the particle size value corresponding to the cumulative particle size distribution in electrolyte particles reaching 90%, and λ is the error control factor, 1≤λ≤1.2, dimensionless, used to correct, compensate and adjust errors.

[0032] In this invention, D50 负极 D90 负极 D50 电解质 D90 电解质 Existing measurement methods can be used, such as sieving, sedimentation, laser, or electron microscopy.

[0033] This invention, through precise control of the size of anode material particles and electrolyte particles, clarifies the quantitative principle of particle size matching and determines the particle matching boundary. Without introducing new materials or complex modifications, it can achieve a comprehensive improvement in capacity, rate capability, and cycle stability simply by selecting the matching size of the active material and electrolyte particles. This technology proposes a quantifiable standard and can accurately solve the core contradiction in all-solid-state composite anode design (the synergy between interface contact and ion transport).

[0034] In some embodiments, the negative electrode sheet comprises the following components by mass fraction: 50-90 wt% negative electrode active material particles, 5-40 wt% electrolyte particles, 0.5-3 wt% binder, and 1-8 wt% conductive agent.

[0035] Preferably, the negative electrode sheet comprises the following components by mass fraction: 60-80 wt% negative electrode active material particles, 15-30 wt% electrolyte particles, 0.5-3 wt% binder, and 1-8 wt% conductive agent.

[0036] In some embodiments, the negative electrode active material is at least one of micron-sized silicon, nano-sized silicon, CVD silicon-carbon, artificial graphite, and natural graphite.

[0037] In some embodiments, the electrolyte includes at least one of a sulfide electrolyte, a halide electrolyte, and an oxide electrolyte.

[0038] Furthermore, the sulfide electrolyte is Li6PS5Cl, Li6PS5Br, or Li 5.5 PS 4.5 Cl 0.7 Br 0.8 Li7PS6, Li7P3S 11 Li6PS5Cl 0.5 Br 0.5 Li 10 GeP2S 12 Li 10 SnP2S 12 Li 3.25 Ge 0.25 P 0.75 At least one of S4, etc.

[0039] In some embodiments, the adhesive is at least one of the following: styrene-ethylene-butadiene-styrene copolymer (SEBS), hydrogenated nitrile butadiene rubber (HNBR), polyethylene, polypropylene, polyisobutylene, amorphous polyalphaolefin, acrylate rubber, etc.

[0040] In some embodiments, the conductive agent is at least one of VGCF (vapor-grown carbon fiber), CNT (carbon nanotube), and graphene.

[0041] The above-mentioned method for preparing the negative electrode sheet for solid-state batteries includes the following steps: Step S1: The electrolyte is ball-milled to obtain electrolyte particles of the target particle size, denoted as material E1; Step S2: Take the negative electrode active material particles of the target particle size and mix them with the material E1 particles in a VC-10 high-efficiency mixer to obtain mixed material E2. Step S3: Add the adhesive to the solvent according to the ratio, and stir mechanically until the solution is clear. Record this as solution F1. Step S4: Add the conductive agent to solution F1 according to the ratio, and stir mechanically to obtain mixed solution F2; Step S5: Add the mixed solution F2 and the mixed material E2 to the planetary mixer in sequence and homogenize to obtain the negative electrode slurry E3. Step S6: Coat the negative electrode slurry E3 onto the surface of the current collector and dry it to obtain the negative electrode sheet for solid-state batteries.

[0042] In some embodiments, the ball milling process in step S1 is as follows: the ball-to-material ratio is 10:1-2:1 (including but not limited to 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1), the ball milling speed is 300-700 rpm (including but not limited to 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm), and the ball milling time is 0.5h-5h (including but not limited to 0.5h, 1h, 2h, 3h, 4h, 5h).

[0043] In some embodiments, the powder mixing process in step S2 is as follows: the mixing speed is 300-1100 rpm (including but not limited to 300 rpm, 500 rpm, 700 rpm, 900 rpm, 1100 rpm), and the mixing time is 0.5h-2h (including but not limited to 0.5h, 1h, 1.5h, 2h).

[0044] In some embodiments, the mechanical stirring speed in step S3 is 800-1000 rpm (including but not limited to 800 rpm, 850 rpm, 900 rpm, 950 rpm, and 1000 rpm).

[0045] In some embodiments, the solvent in step S3 is at least one selected from toluene, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, butyl butyrate, isobutyl butyrate, n-pentyl butyrate, n-pentyl ether, n-hexyl ether, n-heptyl ether, n-octyl ether, and diphenyl ether.

[0046] In some embodiments, the mechanical stirring speed in step S4 is 800-1200 rpm (including but not limited to 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm), and the mechanical stirring time is 1h-3h (including but not limited to 1h, 1.5h, 2h, 2.5h, 3h).

[0047] In some embodiments, the planetary mixer homogenization process in step S5 is as follows: the revolution speed is 20-50 rpm (including but not limited to 20, 25, 30, 35, 45, 50), the rotation speed is 1000-5000 rpm (including but not limited to 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 4500 rpm), and the homogenization time is 0.5h-2h (including but not limited to 0.5h, 1h, 1.5h, 2h).

[0048] In some embodiments, the drying temperature in step S6 is 80-110°C (including but not limited to 80°C, 90°C, 100°C, and 110°C), and the drying is carried out under vacuum or inert atmosphere.

[0049] A solid-state battery employing the aforementioned negative electrode sheet, wherein the positive electrode material is at least one of lithium manganese oxide, lithium iron phosphate, lithium cobalt oxide, nickel-cobalt-manganese ternary materials, elemental sulfur, etc.

[0050] Optionally, the nickel-cobalt-manganese ternary material includes LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.7 Co 0.2 Mn 0.1 O2 (NCM721), LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2 (NCM811).

[0051] Example 1 A method for preparing a negative electrode sheet for a solid-state battery includes the following steps: 1. The sulfide electrolyte Li6PS5Cl was ball-milled in a ball mill at 400 rpm for 1 hour at a ball ratio of 4:1 to obtain D50. 电解质 =0.41μm, D90 电解质 The Li6PS5Cl sulfide electrolyte with a thickness of 2.77 μm is denoted as material E1; 2. Take 70wt% D50 负极 =3.15μm, D90 负极 =5.47μm silicon active material particles with 24wt% D50 电解质 =0.41μm, D90 电解质 Li6PS5Cl sulfide electrolyte particles with a diameter of 0=2.77μm were mixed in a VC-10 high-efficiency mixer at 500rpm for 0.5 hours to obtain mixed material E2 (100wt% refers to the total composition of the negative electrode, including the negative electrode active material, electrolyte, binder, and conductive agent). 3. Take 1 wt% of styrene-ethylene-butadiene-styrene copolymer (SEBS) and add it to toluene solvent. Stir mechanically at 900 rpm until the solution is clear. This solution is called solution F1. (100 wt% refers to the total composition of the negative electrode, including the negative electrode active material, electrolyte, binder, and conductive agent). 4. Take 5 wt% conductive agent VGCF and add it stepwise to solution F1. Stir mechanically at 900 rpm for 2 hours to obtain mixed solution F2; (100 wt% refers to the total composition of the negative electrode, including the negative electrode active material, electrolyte, binder and conductive agent). 5. Add the mixed solution F2 and the mixed material E2 to the planetary mixer in sequence, and homogenize for 1 hour at a revolution speed of 30 rpm and a rotation speed of 2250 rpm to obtain the negative electrode slurry E3. 6. The negative electrode slurry E3 is coated onto the surface of the current collector using a coating machine, and the electrode is dried at 100°C to obtain a negative electrode with high ion conductivity.

[0052] Example 2 The difference between this embodiment and Embodiment 1 is that, in steps 1 and 2, the particle size of the Li6PS5Cl sulfide electrolyte particles is D50. 电解质 =0.37μm, D90 电解质 =4.8μm, and other conditions and parameters are exactly the same as in Example 1.

[0053] Example 3 The difference between this embodiment and Embodiment 1 is that, in steps 1 and 2, the particle size of the Li6PS5Cl sulfide electrolyte particles is D50. 电解质 =0.41μm, D90 电解质 =1.5μm, and other conditions and parameters are exactly the same as in Example 1.

[0054] Example 4 The difference between this embodiment and Embodiment 1 is that, in steps 1 and 2, the particle size of the Li6PS5Cl sulfide electrolyte particles is D50. 电解质 =0.29μm, D90 电解质 =6μm, and other conditions and parameters are exactly the same as in Example 1.

[0055] Example 5 The difference between this embodiment and embodiment 1 is that in step 2, D50 is added. 负极 =2.5μm, D90 负极 =6μm silicon active material particles, and other conditions and parameters are exactly the same as in Example 1.

[0056] Example 6 The difference between this embodiment and embodiment 1 is that in step 2, D50 is added. 负极 =3.15μm, D90 负极 =5.47μm artificial graphite material particles, with other conditions and parameters exactly the same as in Example 1.

[0057] Example 7 The difference between this embodiment and Embodiment 1 is that, in steps 1 and 2, the sulfide electrolyte is Li. 5.5 PS 4.5 Cl 0.7 Br 0.8 Li 5.5 PS 4.5 Cl 0.7 Br 0.8 The particle size of the sulfide electrolyte particles is D50. 电解质 =0.41μm, D90 电解质 =2.77μm, and other conditions and parameters are exactly the same as in Example 1.

[0058] Comparative Example 1 The difference between this comparative example (with larger electrolyte particles) and Example 1 is that in steps 1 and 2, the particle size of the Li6PS5Cl sulfide electrolyte particles is D50. 电解质 =4.5μm, D90 电解质 =8.9μm, and other conditions and parameters are exactly the same as in Example 1.

[0059] Comparative Example 2 The difference between this comparative example (with smaller electrolyte particles) and Example 1 is that in steps 1 and 2, the particle size of the Li6PS5Cl sulfide electrolyte particles is D50. 电解质 =0.2μm, D90 电解质 =2μm, and other conditions and parameters are exactly the same as in Example 1.

[0060] Comparative Example 3 The difference between this comparative example (with larger negative electrode material particles) and Example 1 is that in step 2, D50 is added. 负极 =7μm, D90 负极 =15μm silicon active material particles, and other conditions and parameters are exactly the same as in Example 1.

[0061] Comparative Example 4 The difference between this comparative example (with smaller negative electrode material particles) and Example 1 is that in step 2, D50 is added. 负极 =1.5μm, D90 负极 =4μm silicon active material particles, and other conditions and parameters are exactly the same as in Example 1.

[0062] Experimental example: I. Negative electrode sheets were prepared using Examples 1-7 and Comparative Examples 1-4, and battery electrode sheets were fabricated and all-solid-state soft-pack cells were assembled. The specific steps are as follows: S1. Preparation of positive electrode sheet Weigh out the four substances according to the mass ratio of active material: sulfide electrolyte: conductive agent (VGCF) and polyvinylidene fluoride (PVDF) = 70:25:4.5:0.5, and place them in a ball mill jar and seal it. Mix the four materials evenly at 450 rpm. Then knead the dry powder mixture and roll it with a roller press until the surface density is 26±0.2 mg / cm³. 2 The positive electrode membrane (40±0.5*40±0.5mm) is cut using a die-cutting machine, then attached to the current collector surface, weighed, and kept for later use. S2, Electrolyte Membrane Fabrication Dissolve 2% SEBS adhesive in toluene solution, apply it to the surface of aluminum foil, and dry it at 90°C under vacuum for 12 hours; S3, Electrode Transfer The positive electrode sheet prepared in step S1 is bonded to the electrolyte in step S2, and then sealed and encapsulated. The transfer is then performed under isostatic pressure of 80°C and 150MPa. S4, Assemble the battery Ah-grade soft-pack batteries were assembled in a glove box filled with a high-purity argon atmosphere, where the contents of H2O and O2 were both less than 0.1 ppm. The positive electrode sheet that had been completely transferred in step S3 was combined with the negative electrode sheet prepared in Examples 1-7 and Comparative Examples 1-4 to complete the battery assembly. After assembly, isostatic pressing was performed at 500 MPa / 80°C to complete the battery fabrication.

[0063] II. Electrochemical performance testing and analysis: Constant current charge / discharge tests were performed using the LAND CT2001A battery testing system. The charge / discharge voltage window was 2.5~4.25 V. The test results for full battery capacity, first efficiency, cycle performance, and negative electrode ionic conductivity are shown in Table 1.

[0064] Table 1. Data on the capacity, first-cycle efficiency, cycle performance, and ionic conductivity of the negative electrode sheets assembled in Examples 1-7 and Comparative Examples 1-4.

[0065] As shown in Table 1, the electrochemical data from Examples 1-7 and Comparative Examples 1-4 demonstrate that this solid-state negative electrode, through precise particle matching, forms a hierarchical ion conduction network in the composite negative electrode, achieving synergistic optimization of interface contact and ion transport. This hierarchical structure, characterized by "fine particles filling gaps and medium particles building channels," enables lithium ions to quickly reach the surface of each negative electrode material particle and efficiently transport through continuous channels, achieving dual optimization of capacity and rate capability. The negative electrode active material particles and solid electrolyte particles in this invention are not simply a physical mixture of sizes, but rather adhere to specific design principles: the sizes of the negative electrode active material particles and solid electrolyte particles in the solid composite negative electrode conform to: 9 ≤ λ (D50). 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 )≤12, where λ is the error control factor (1≤λ≤1.2), which can simultaneously improve the performance of electrode ion conductivity, discharge capacity, rate performance and cycle stability.

[0066] The electrochemical data from Examples 1-7 show that Examples 1-7 involve changes in the particle size of the negative electrode particles, the particle size of the electrolyte particles, and the types of negative electrode materials and electrolytes. However, the sizes of the negative electrode active material particles and solid electrolyte particles in the solid composite negative electrodes of Examples 1-7 all conform to the following: 9 ≤ λ (D50) 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 If λ ≤ 12, where λ is the error control factor (1 ≤ λ ≤ 1.2), a good hierarchical ion conduction network can be formed in the negative electrode, thereby improving the specific capacity, rate capability, first-time efficiency, and cycle life of the battery to varying degrees. In Example 6, due to the low expansion property of graphite material, more stable cycle performance can be achieved under the quantitative principle of particle size matching; Example 7 uses Li... 5.5 PS 4.5 Cl 0.7 Br 0.8 As a sulfide electrolyte, this type of electrolyte exhibits higher intrinsic ionic conductivity, thus demonstrating superior rate performance under this quantitative guideline. In summary, the quantitative design principle for particle arrangement in the negative electrode is: 9 ≤ λ (D50) 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质)≤12, where λ is the error control factor (1≤λ≤1.2), which has universality and can guide the design of the negative electrode sheet and optimize the overall performance of the battery.

[0067] The electrochemical data from Examples 1-5 and Comparative Examples 1 and 4 show that the particle design in Comparative Examples 1 and 4 does not conform to 9≤λ(D50). 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 When λ ≤ 12, where λ is the error control factor (1 ≤ λ ≤ 1.2), due to the pairing of negative electrode material particles with relatively large electrolyte particles, the large electrolyte particles cannot fill the gaps between the negative electrode material particles, resulting in the electrolyte being distributed in an "island-like" manner. The ion conduction network is broken, and the interface contact is insufficient, which in turn leads to a low capacity utilization and a decrease in rate performance, making it impossible to fully utilize the performance of the solid electrode.

[0068] The electrochemical data from Examples 1-5 and Comparative Examples 2 and 3 show that the particle design in Comparative Examples 2 and 3 does not conform to 9≤λ(D50). 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 When λ ≤ 12, where λ is the error control factor (1 ≤ λ ≤ 1.2), due to the combination of negative electrode material particles and relatively small electrolyte particles, the electrolyte particles are too small. Although they can fill the gaps between negative electrode material particles, there is a lack of sufficient medium-sized particles to construct fast conduction channels, which may increase interfacial impedance and reduce ion conduction efficiency, especially bulk ion transport efficiency, resulting in a decline in the performance of the electrode and exhibiting worse cycle stability and rate performance.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A negative electrode sheet for solid-state batteries, characterized in that, The negative electrode is a solid composite negative electrode, comprising negative electrode active material particles and electrolyte particles. The particle size of the negative electrode active material particles and the particle size of the electrolyte particles conform to the following condition: 9 ≤ λ (D50). 负极 *D90 电解质 +D50 电解质 *D90 负极 ) / (D50 电解质 *D90 电解质 )≤12, where λ is the error control factor, 1≤λ≤1.

2.

2. The negative electrode sheet for a solid-state battery according to claim 1, characterized in that, The negative electrode sheet comprises the following components by mass fraction: 50-90 wt% negative electrode active material particles, 5-40 wt% electrolyte particles, 0.5-3 wt% binder, and 1-8 wt% conductive agent.

3. The negative electrode sheet for a solid-state battery according to claim 1 or 2, characterized in that, Includes at least one of the following technical features: (1) The negative electrode sheet comprises the following components by mass fraction: 60-80 wt% negative electrode active material particles, 15-30 wt% electrolyte particles, 0.5-3 wt% binder, and 1-8 wt% conductive agent; (2) The negative electrode active material is at least one of micron-sized silicon, nano-sized silicon, CVD silicon carbide, artificial graphite, and natural graphite; (3) Electrolytes include at least one of sulfide electrolytes, halide electrolytes, and oxide electrolytes.

4. The negative electrode sheet for a solid-state battery according to claim 3, characterized in that, Includes at least one of the following technical features: (1) The adhesive is at least one of styrene-ethylene-butadiene-styrene copolymer, hydrogenated nitrile rubber, polyethylene, polypropylene, polyisobutylene, amorphous polyalphaolefin, and acrylate rubber; (2) The conductive agent is at least one of VGCF, CNT, and graphene; (3) The sulfide electrolyte is Li6PS5Cl, Li6PS5Br, Li 5.5 PS 4.5 Cl 0.7 Br 0.8 Li7PS6, Li7P3S 11 Li6PS5Cl 0.5 Br 0.5 Li 10 GeP2S 12 Li 10 SnP2S 12 Li 3.25 Ge 0.25 P 0.75 At least one of S4.

5. The method for preparing the negative electrode sheet for a solid-state battery as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step S1: The electrolyte is ball-milled to obtain electrolyte particles of the target particle size, denoted as material E1; Step S2: Take the negative electrode active material particles of the target particle size according to the ratio and mix them evenly with the material E1 particles to obtain the mixed material E2. Step S3: Add the adhesive to the solvent according to the ratio, and stir mechanically until the solution is clear. Record this as solution F1. Step S4: Add the conductive agent to solution F1 according to the ratio, and stir mechanically to obtain mixed solution F2; Step S5: Homogenize the mixed solution F2 with the mixed material E2 to obtain the negative electrode slurry E3; Step S6: Coat the negative electrode slurry E3 onto the surface of the current collector and dry it to obtain the negative electrode sheet for solid-state batteries.

6. The method for preparing the negative electrode sheet for a solid-state battery according to claim 5, characterized in that, Includes at least one of the following technical features: (1) The ball milling process in step S1 is as follows: the ball-to-material ratio is 10:1-2:1, the ball milling speed is 300-700 rpm, and the ball milling time is 0.5h-5h; (2) The powder mixing process in step S2 is as follows: the mixing speed is 300-1100 rpm and the mixing time is 0.5h-2h.

7. The method for preparing the negative electrode sheet for a solid-state battery according to claim 5, characterized in that, Includes at least one of the following technical features: (1) The mechanical stirring speed in step S3 is 800-1000 rpm; (2) The solvent mentioned in step S3 is at least one of toluene, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, butyl butyrate, isobutyl butyrate, n-pentyl butyrate, n-pentyl ether, n-hexyl ether, n-heptyl ether, n-octyl ether, and diphenyl ether; (3) In step S4, the mechanical stirring speed is 800-1200 rpm and the mechanical stirring time is 1h-3h.

8. The method for preparing the negative electrode sheet for a solid-state battery according to claim 5, characterized in that, Includes at least one of the following technical features: (1) In step S5, a planetary mixer is used for homogenization. The revolution speed is 20-50 rpm, the rotation speed is 1000-5000 rpm, and the homogenization time is 0.5h-2h. (2) In step S6, the drying temperature is 80-110℃, and the drying is carried out under vacuum or inert atmosphere.

9. A solid-state battery, comprising a negative electrode sheet for a solid-state battery as described in any one of claims 1 to 4 or a negative electrode sheet prepared by the preparation method as described in any one of claims 5 to 8, characterized in that, The cathode material used in this solid-state battery is at least one of lithium manganese oxide, lithium iron phosphate, lithium cobalt oxide, nickel-cobalt-manganese ternary materials, and elemental sulfur.

10. The solid-state battery according to claim 9, characterized in that, The nickel-cobalt-manganese ternary material includes LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2.

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