Solid-state battery negative electrode, preparation method, solid-state battery and formation process

Abstract

The application discloses a kind of solid-state battery negative electrode, preparation method and solid-state battery and formation process, the negative electrode includes negative electrode main material and composite in the surface or interface of the negative electrode main material Nano alloy particles;The mass ratio of the nano alloy particles and the negative electrode main material is 1:2~5, the Young's modulus of the nano alloy particles is ≤70GPa, and the lithium ion diffusion coefficient of nano alloy powder is ≥cm² / s;The ratio of D50 and D90 of the nano alloy particles is 1:1~1.1, the ratio of D50 and D90 of the negative electrode main material is 1:1.25~5, and the ratio of D50 of the nano alloy particles and the D50 of the negative electrode main material is 1:10~20.The composite negative electrode combines special formation process, can realize high specific capacity, excellent rate performance and long cycle life simultaneously.Nano alloy particles not only improve the structure, its own high ionic conductivity also directly improves the reaction kinetics of electrode.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state battery technology, specifically to a solid-state battery anode, a preparation method, a solid-state battery, and a formation process. Background Technology

[0002] With the rapid development of technology and the steady improvement of living standards, people have placed higher demands on the performance of lithium-ion batteries, focusing on three core dimensions: safety, energy density, and high-rate fast charging capability. All-solid-state batteries, with their excellent compatibility with high-capacity positive and negative electrode materials, are expected to simultaneously enhance battery safety and energy density, demonstrating broad application prospects.

[0003] However, in all-solid-state battery systems, there are still many technical bottlenecks in anode materials: lithium ions diffuse slowly in traditional anodes such as graphite and silicon-carbon, making it difficult to form a continuous and efficient ion transport pathway; at the same time, the volume expansion of the anode during charging and discharging can easily lead to interface contact failure. These problems directly cause lithium plating and short circuits during high-rate charging, as well as rapid capacity decay, severely restricting the practical application of all-solid-state batteries.

[0004] Currently, traditional anode materials, battery fabrication technologies, and formation processes cannot fully leverage the inherent advantages of all-solid-state batteries in terms of high energy density and long cycle life. Specifically, the core issues that urgently need to be addressed include: poor rate performance of the anode, insufficient interface stability caused by volume changes, lack of structural designs adapted to volume changes, and the absence of an efficient formation process suitable for all-solid-state batteries.

[0005] To address the aforementioned issues, this invention designs a novel anode structure specifically for all-solid-state batteries, effectively solving key challenges such as slow lithium intercalation speed, easy lithium deposition, and electrochemical performance degradation at high rates. Simultaneously, a dedicated battery formation process has been developed to complement this novel anode structure, further optimizing interface stability and lithium-ion transport kinetics. Furthermore, the preparation method provided by this invention is simple and easily scalable for mass production, offering a practical technical solution for achieving stable long-term cycling at high rates in all-solid-state lithium batteries. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a solid-state battery anode, its preparation method, a solid-state battery, and a formation process. The present invention addresses the shortcomings of anode materials, including poor rate performance, insufficient interfacial stability due to volume changes, lack of structural design adaptable to volume changes, and the absence of a highly efficient formation process suitable for all-solid-state batteries. Based on these deficiencies, this application provides a solid-state battery anode, its preparation method, a solid-state battery, and a formation process to improve the problems of slow lithium intercalation speed, easy lithium plating, and electrochemical performance degradation in solid-state batteries under high-rate conditions in related technologies.

[0007] This invention is achieved through the following technical solution:

[0008] A solid-state battery anode includes a main anode material and nano-alloy particles composited on the surface or interface of the main anode material; the mass ratio of the nano-alloy particles to the main anode material is 1:2~5, the Young's modulus of the nano-alloy particles is ≤70 GPa, and the lithium-ion diffusion coefficient of the nano-alloy powder is ≥10. -12 cm² / s; the ratio of D50 to D90 of the nano-alloy particles is 1:1 to 1.1, the ratio of D50 to D90 of the negative electrode main material is 1:1.25 to 5, and the ratio of D50 of the nano-alloy particles to D50 of the negative electrode main material is 1:10 to 20. In the technical solution of the present invention, in the solid-state battery negative electrode structure, the negative electrode main material serves as the main lithium-ion storage medium and contributes to the capacity; the nano-alloy particles are used to homogenize the electric field within the negative electrode, improve short-range ion and electron transport between particles, and simultaneously reduce the porosity inside the negative electrode and increase the compaction density of the solid-state battery negative electrode.

[0009] The negative electrode material is selected from one or more of graphite, silicon-carbon, silicon-oxygen-carbon, and silicon; the nano-alloy particles are selected from one or more of magnesium, aluminum, indium, silver, tin, and germanium.

[0010] The nano-alloy particles have a D50 of 0.1~1μm; the negative electrode material has a D50 of 1~20μm and a D90 of 1~25μm.

[0011] The solid-state battery anode structure is achieved through the following steps: first, the materials are initially composited through mechanical mixing; then, the interface is activated and reconstructed through a proprietary formation process, so that the nano-alloy particles are refined and uniformly dispersed on the interface of the anode main material, thus completing the final construction of the anode structure.

[0012] In the above process, by setting the mass ratio of nano-alloy particles to the anode material to 1:2~5, the rate performance and cycle stability can be effectively improved while maintaining the high capacity of the anode.

[0013] In the above process, the Young's modulus of the nano-alloy particles is ≤70GPa, which has good ductility and is easy to compress and deform. This can further improve the compaction density of the negative electrode and reduce the porosity, thereby realizing the construction of a short-range ion conduction network inside the negative electrode.

[0014] In the above process, the lithium-ion diffusion coefficient of the nano-alloy powder is ≥10. -12 cm 2 / s can improve ion transport between nano-alloy particles and between alloy particles and the negative electrode material, enabling rapid lithium-ion migration.

[0015] By controlling the particle size ratio and particle size distribution of nano-alloy particles and the main anode material, the internal porosity of the anode can be effectively reduced, the compaction density can be increased, and the transport path of lithium ions in the anode can be optimized, thereby improving the rate performance and cycle life of solid-state batteries.

[0016] In the above process, the ratio of D50 of the nano-alloy particles to D50 of the negative electrode material is 1:10~20, the ratio of D50 of the alloy powder to D90 is 1:1~1.1, and the ratio of D50 of the negative electrode material to D90 is 1:1.25~5. This can reduce the internal porosity of the negative electrode, increase the compaction density, and realize lithium-ion transport inside the negative electrode. When applied to solid-state batteries, it can improve the rate performance and cycle stability of solid-state batteries.

[0017] In conjunction with the first aspect, the D50 of the nano-alloy particles is 0.1~1μm; the D50 of the negative electrode main material is 1~20μm. This particle size range ensures that the nano-alloy particles are uniformly filled in the gaps of the negative electrode main material. After densification treatment, they undergo plastic deformation to form a continuous ion and electron transport network at the negative electrode interface, thereby improving the electrochemical performance of the battery.

[0018] In conjunction with the first aspect, the D90 of the negative electrode main material is 1~25μm. This particle size distribution can balance the compaction density and porosity of the negative electrode, which is conducive to the densification of the main material and also reserves suitable channels for ion transport, further improving the ion and electron transport efficiency of the negative electrode.

[0019] In the above implementation process, the D50 of the negative electrode main material is 1~20μm and the D90 is 1~25μm. In solid-state batteries, after the negative electrode is densified, it can facilitate the compaction of the negative electrode main material, reduce the porosity between the negative electrode main materials, improve the ion and electron transport inside the negative electrode, and thus improve the electrochemical performance of the solid-state battery.

[0020] In conjunction with the first aspect, the D50 of the nano-alloy particles is 0.5~1μm, and the D90 is 0.1~1μm. These parameters ensure the uniformity of the nano-alloy particle size, improve their dispersibility on the surface of the negative electrode main material, effectively fill the gaps between the main materials, reduce the porosity of the negative electrode, improve the battery interface contact, and suppress the risk of overcharging and short circuit.

[0021] In conjunction with the first aspect, the Young's modulus of the nanoalloy particles is 40 GPa. This low Young's modulus endows the particles with excellent ductility, facilitates compressive deformation, and can significantly improve the compaction density of the negative electrode, reduce porosity, and efficiently construct a short-range ion conduction network.

[0022] In conjunction with the first aspect, the lithium-ion diffusion coefficient of the nano-alloy powder is 10. -7 cm 2 / s. This high diffusion coefficient can significantly accelerate the interfacial ion transport rate, enabling rapid lithium-ion migration and enhancing battery rate performance.

[0023] In conjunction with the first aspect, the mass ratio of nano-alloy particles to the anode material is 1:2~5, which can minimize the impact on the capacity of the anode material and further improve the compaction density of the anode, reduce porosity, and thus improve the electrochemical performance of solid-state batteries.

[0024] In conjunction with the first aspect, the negative electrode material is selected from one or more of graphite, silicon-carbon, silicon-oxygen-carbon, or silicon; the nano-alloy particles are selected from one or more of magnesium powder, aluminum powder, indium powder, silver powder, tin powder, and germanium powder. All of the above raw materials possess good electrochemical compatibility and feasibility, and can be flexibly combined according to battery performance requirements.

[0025] The method for preparing a solid-state battery anode as described above includes the following steps:

[0026] S1. Premixing: The negative electrode material and nano-alloy particles are mechanically mixed to obtain a primary composite material;

[0027] S2. Slurry preparation and molding: The primary composite material, solid electrolyte and binder are mixed to form a slurry, which is then coated, dried and rolled to obtain the negative electrode sheet.

[0028] In step S1, the mechanical mixing method is at least one of ball milling, airflow mixing, sand milling, or ultrasonic vibration.

[0029] The preferred method for mechanical mixing is ball milling, with a rotation speed of 100~500 rpm and a time of 1~2 hours.

[0030] In step S2, the mass ratio of the primary composite material, solid electrolyte, and binder is (50-80):(5-20):(1-5);

[0031] The solid electrolyte is at least one of sulfide solid electrolyte, halide solid electrolyte, or oxide solid electrolyte;

[0032] The adhesive is at least one of polyvinylidene fluoride, polystyrene, polyisobutylene, styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyacrylic acid, or carboxymethyl cellulose.

[0033] In the above process, the nano-alloy particles and the negative electrode main material are mixed in a mass ratio of 1:2~5, the ratio of D50 of the nano-alloy particles to D50 of the negative electrode main material is 1:10~20, the ratio of D50 of the alloy powder to D90 is 1:1~1.1, and the ratio of D50 of the negative electrode main material to D90 is 1:1.25~5. The mixture of nano-alloy particles and negative electrode main material, solid electrolyte and binder are wet-mixed in a mass ratio of (50-80):(5~20):(1~5) to prepare a negative electrode slurry and then coated and molded.

[0034] In conjunction with the second aspect, the mixing method between the nano-alloy particles and the negative electrode material includes at least one of wet ball milling, sand milling, or ultrasonic vibration. This ensures uniform compounding and improves interfacial adhesion.

[0035] In conjunction with the second aspect, the solid electrolyte includes at least one of a sulfide solid electrolyte, a halide solid electrolyte, or an oxide solid electrolyte. It possesses good ionic conductivity and interfacial compatibility.

[0036] In conjunction with the second aspect, the binder includes at least one selected from polyvinylidene fluoride, polystyrene, polyisobutylene, styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyacrylic acid, or carboxymethyl cellulose. This allows for uniform dispersion of the components, forming a stable slurry.

[0037] In conjunction with the second aspect, the solvent includes at least one of toluene, xylene, butyl ether, DMF, DMAC, NMP, etc.

[0038] In conjunction with the second aspect, the coating method is at least one of the following: blade coating, transfer coating, extrusion coating, spin coating, and spray coating. The appropriate method can be selected based on production requirements to ensure uniform electrode thickness.

[0039] A solid-state battery, comprising the solid-state battery negative electrode or negative electrode sheet.

[0040] In a third aspect, an example of this application provides a solid-state battery, including a solid-state battery negative electrode material provided in the first aspect and a solid-state battery negative electrode sheet provided in the second aspect. The solid-state battery is assembled by sequentially stacking the all-solid-state battery negative electrode sheet, positive electrode sheet, and solid electrolyte membrane.

[0041] The solid-state battery formation process described above includes the following steps:

[0042] P1, Pressure Pre-tightening: Applying an initial pressure of 5~50MPa to the assembled and densified solid-state battery;

[0043] P2, Stepwise activation: At an ambient temperature T1 of 50~80℃, the battery is subjected to stepwise charge-discharge cycles with a current of 0.1C~0.5C. The state of charge (SOC) steps of the charge-discharge cycles are 20%SOC, 50%SOC, 80%SOC and 100%SOC respectively.

[0044] P3, Hot Isostatic Press Densification: The battery that has undergone step P2 is treated by applying an isostatic pressure of 300-600 MPa at an ambient temperature T2 of 80-100℃.

[0045] P4, Final Formation: The battery that has passed through step P3 is subjected to a pressure of 5~50MPa again and charged to 100% SOC with a constant current of 0.1C.

[0046] In step P2, the stepped charge-discharge cycle refers to first charging to the SOC at each state of charge step, and then discharging to the same depth of discharge SOD at a constant current.

[0047] This application provides an example of a solid-state battery formation process applicable to the solid-state battery anode material described in the first aspect, the anode sheet provided in the second aspect, and the solid-state battery described in the third aspect. The specific steps are as follows:

[0048] Step 1: Apply pressure to the densified solid-state battery using a fixture, preferably at a pressure of 5 MPa to 50 MPa. This pressure can drive the migration and plastic deformation of the nano-alloy particles, reducing the interfacial porosity; if the pressure is too low, the above effect cannot be achieved.

[0049] Step 2: Adjust the ambient temperature of the solid-state battery to T1; charge the solid-state battery with a constant current to 20% SOC, then discharge it with a constant current to 20% SOD; charge the solid-state battery with a constant current to 50% SOC, then discharge it with a constant current to 50% SOD; charge the solid-state battery with a constant current to 80% SOC, then discharge it with a constant current to 80% SOD; charge the solid-state battery with a constant current to 100% SOC, then discharge it with a constant current to 100% SOD; wherein 80℃ ≥ T1 ≥ 50℃, and the current is 0.1C to 0.5C. This process can achieve the refinement and uniform dispersion of nano-alloy particles and optimize the interfacial contact state.

[0050] Step 3: The solid-state battery from Step 2 undergoes isostatic densification treatment with an isostatic pressure of 300MPa to 600MPa and an isostatic ambient temperature T2, where 100℃ ≥ T2 ≥ 80℃. This further improves the density of the negative electrode and the interfacial bonding.

[0051] Step 4: Apply pressure to the solid-state battery from Step 3 using a clamp. Preferably, the pressure applied to the solid-state battery by the clamp in Step 1 is 5MPa to 50MPa. Charge the solid-state battery to 100% SOC at a constant current of 0.1C.

[0052] In the above implementation process, the solid-state battery provided in the embodiments of this application includes the solid-state battery anode provided in the first and second aspects and the formation process provided in the fourth aspect. The solid-state battery anode has low porosity and interfacial gap, and has high rate performance, which can improve the electrochemical performance of the solid-state battery such as charge and discharge.

[0053] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0054] This invention introduces nano-alloy particles with specific parameters as a composite phase and designs them to match the particle size of the anode material, thereby constructing an electrode structure with low porosity that facilitates densification from the outset, solving the fundamental problem of poor ion transport pathways in solid-state electrodes. This composite anode, combined with a specialized formation process, further refines and homogenizes the nano-alloy particles, achieving high specific capacity, excellent rate performance, and long cycle life. The nano-alloy particles not only improve the structure, but their high ionic conductivity also directly enhances the electrode's reaction kinetics. Attached Figure Description

[0055] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0056] Fig. 1 This is a schematic diagram of the composite negative electrode structure of the present invention;

[0057] Fig. 2 This is a microscopic morphology diagram of the negative electrode sheet in Embodiment 1 of the present invention;

[0058] Fig. 3 This is a schematic diagram of the charge-discharge performance curves of the all-solid-state lithium-ion battery assembled from the negative electrode obtained in Example 1 of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0060] refer to Figs. 1-3 This application provides a novel negative electrode for an all-solid-state battery, comprising a main negative electrode material and nano-alloy particles (in the figure, 101 is the main negative electrode material, and 102 is the nano-alloy particle). The ratio of the D50 of the main negative electrode material to the D50 of the nano-alloy particles is 1:10~20, and the ratio of the D50 to D90 of the main negative electrode material is 1:1.25~5, the ratio of the D50 to D90 of the nano-alloy particles is 1:1~1.1, and the mass ratio of the nano-alloy particles to the main negative electrode material is 1:2~5; the Young's modulus of the nano-alloy particles is ≤70 GPa; and the lithium-ion diffusion coefficient of the nano-alloy particles is ≥10. -12 cm 2 / s.

[0061] The core of this anode fabrication lies in: first, pre-mixing the anode main material and nano-alloy particles, allowing the nano-alloy particles to fill the gaps between the anode main material; then, controlling the pulverization and migration of the nano-alloy particles through electrochemical formation to achieve uniform dispersion on the surface of the anode main material. The aforementioned particle size parameters optimize the anode pore structure: anode main materials with different particle sizes help reduce porosity and increase compaction density, while uniformly sized nano-alloy particles can further fill the gaps between the main material, enhancing the anode's densification.

[0062] In some possible embodiments, the ratio of the D50 of the negative electrode material to the D50 of the nano-alloy particles can be one of 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20 or any range between the two.

[0063] If the ratio of the particle size of the negative electrode material to the D50 of the nano-alloy particles is too small, the nano-alloy particles will not be able to fill the gaps in the negative electrode material, thus affecting densification and preventing the construction of a good ion transport network. If the ratio of the particle size of the negative electrode material to the D50 of the nano-alloy particles is too large, the nano-alloy particles will be difficult to disperse uniformly, which will also affect the filling of the gaps in the negative electrode material.

[0064] In some possible embodiments, the ratio of D50 to D90 of the negative electrode material can be one of 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45, 1:1.5, 1:1.55, 1:1.6, 1:1.65, 1:1.7, 1:1.75, 1:1.8, 1:1.85, 1:1.9, 1:1.95, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5, or a range between any two of them.

[0065] If the D50 to D90 ratio of the negative electrode material is less than 1:5, the particle size non-uniformity of the negative electrode material is relatively large, which will increase the internal porosity of the negative electrode, affect the densification of the solid-state negative electrode, reduce the continuity of the lithium-ion transport network, and is detrimental to lithium-ion transport within the negative electrode. If the D50 to D90 ratio of the negative electrode material is greater than 1:2.5, the particle size non-uniformity of the negative electrode material is relatively small, which will also affect the internal porosity of the negative electrode. If the porosity is too low, it will be difficult for nano-alloy particles to fill the gaps, which will affect the charge-discharge rate performance of the solid-state battery when applied to it.

[0066] In some possible embodiments, the ratio of D50 to D90 of the nanoalloy particles can be one of 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, 1:1 or any range between both.

[0067] If the ratio of D50 to D90 of the nano-alloy particles is less than 1:1.1, the non-uniformity of the nano-alloy particle size increases, making it difficult to fill the gaps in the negative electrode material uniformly.

[0068] In some possible embodiments, the D50 of the negative electrode material can be 2~15μm.

[0069] For example, the D50 of the negative electrode material can be one of or between any two of the following: 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm, or 15μm.

[0070] In some possible embodiments, the D90 of the negative electrode material can be 5~17μm.

[0071] For example, the D90 of the negative electrode material can be one of or between any two of the following: 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm, 15μm, 15.5μm, 16μm, 16.5μm, or 17μm.

[0072] For example, the D50 of the negative electrode material is 2μm and the D90 is 5μm.

[0073] For example, the D50 of the negative electrode material is 2μm and the D90 is 10μm.

[0074] For example, the D50 of the negative electrode material is 5 μm and the D90 is 15 μm.

[0075] For example, the negative electrode material has a D50 of 10 μm and a D90 of 17 μm.

[0076] In some possible embodiments, the D50 of the nanoalloy particles can be 0.5~1μm.

[0077] For example, the D50 of the nanoalloy particles can be one of or between any two of 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm or 1 μm.

[0078] For example, the D50 of the negative electrode material can be 5 μm, and the D50 of the nano-alloy particles can be 0.5 μm.

[0079] For example, the D50 of the negative electrode material can be 2 μm, and the D50 of the nano-alloy particles can be 0.5 μm.

[0080] In some possible embodiments, the D90 of the nanoalloy particles can be 0.5~1μm.

[0081] For example, the D90 of the nanoalloy particles can be one of or between any two of 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm or 1 μm.

[0082] For example, the D50 of the nano-alloy particles can be 0.8 μm and the D90 can be 0.85 μm.

[0083] For example, the D50 of the nano-alloy particles can be 0.5 μm and the D90 can be 0.5 μm.

[0084] For example, the D50 of the nano-alloy particles can be 1 μm, and the D90 can be 1 μm.

[0085] Preferably, in the solid-state battery anode, the D50 of the anode main material is 5 μm and the D90 is 8 μm; the D50 of the nano-alloy particles is 0.8 μm and the D90 is 0.85 μm. This combination of parameters achieves optimal density and ion transport efficiency.

[0086] The mass ratio of the negative electrode material to the nano-alloy particles is 1:2~5, which can maximize the capacity of the negative electrode and obtain the highest compaction density.

[0087] In some possible embodiments, the mass ratio of the negative electrode material to the nano-alloy particles can be one of 1:2, 1:3, 1:4, or 1:5, or any range between two of these. If the mass ratio of the negative electrode material to the nano-alloy particles is too small, it will result in a low degree of densification of the negative electrode, and the specific capacity of the solid-state negative electrode will be close to that of the negative electrode material. If the mass ratio of the negative electrode material to the nano-alloy particles is too large, it will result in a high degree of densification of the negative electrode, but a low specific capacity of the solid-state negative electrode.

[0088] The nano-alloy particles have a Young's modulus ≤70GPa and good plastic deformation characteristics. They are conducive to extrusion creep during densification, connecting the gaps between the main negative electrode materials and improving the densification of the solid negative electrode.

[0089] In some possible embodiments, the Young's modulus of the nanoalloy particles can be 1~70 GPa.

[0090] For example, the Young's modulus of the nanoalloy particles is in the range of one or any two of 70 GPa, 60 GPa, 50 GPa, 40 GPa, 30 GPa, 20 GPa, 10 GPa, 9 GPa, 8 GPa, 7 GPa, 6 GPa, 5 GPa, 4 GPa, 3 GPa, 2 GPa or 1 GPa.

[0091] Preferably, the Young's modulus of the nano-alloy particles is 20 GPa to 41 GPa, which can balance ductility and structural stability.

[0092] The lithium-ion diffusion coefficient of the nano-alloy particles is ≥10. -12 A high lithium-ion diffusion coefficient of cm2 / s helps improve the rate performance of the solid-state battery anode, homogenizes the lithium-ion concentration field, and avoids lithium plating short circuits during high-rate fast charging.

[0093] In some possible embodiments, the lithium-ion diffusion coefficient of the nanoalloy particles can be 10. -5 ~10 -12 cm 2 / s.

[0094] For example, the lithium-ion diffusion coefficient of the nano-alloy particles can be 10. -5 cm 2 / s、10 -6 cm 2 / s、10 -7 cm 2 / s、10 -8 cm 2 / s、10 -9 cm 2 / s、10 -10 cm 2 / s、10 -11 cm 2 / s or 10 -12 cm 2 / s is a range of one or both of them.

[0095] Preferably, the lithium-ion diffusion coefficient of the nano-alloy particles can be 10. -5 cm 2 / s~10 -7 cm 2 / s enables efficient ion transport.

[0096] The negative electrode material is mixed with nano-alloy particles by at least one of wet ball milling, sand milling or ultrasonic vibration, which can ensure that the two are uniformly compounded.

[0097] Furthermore, this application also provides a method for preparing a solid-state battery negative electrode sheet, including:

[0098] The nano-alloy particles are wet-mixed with the negative electrode material mixture, solid electrolyte and binder in a mass ratio of (50-80):(5~20):(1~5) to form a slurry. The slurry is then coated, dried and rolled to obtain the negative electrode sheet.

[0099] In conjunction with the second aspect, in optional embodiments of this application, the method for mixing nano-alloy particles with the negative electrode material includes at least one of wet ball milling, sand milling, or ultrasonic vibration.

[0100] In some possible embodiments, the solid electrolyte can be one of a sulfide solid electrolyte, a halide solid electrolyte, a polymer electrolyte, or an oxide solid electrolyte.

[0101] Preferably, the solid electrolyte can be a sulfide solid electrolyte, which has higher ionic conductivity.

[0102] In conjunction with the second aspect, in optional embodiments of this application, the adhesive includes at least one of polyvinylidene fluoride, polystyrene, polyisobutylene, styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyacrylic acid, or carboxymethyl cellulose.

[0103] In conjunction with the second aspect, in optional embodiments of this application, the solvent includes at least one of toluene, xylene, butyl ether, DMF, DMAC, NMP, etc.

[0104] In conjunction with the second aspect, in optional embodiments of this application, the coating is at least one of blade coating, transfer coating, extrusion coating, spin coating, spray coating, etc.

[0105] The all-solid-state battery provided in the third aspect of this application includes the aforementioned negative electrode, positive electrode, and solid electrolyte membrane, which are sequentially stacked and assembled, with the negative electrode located between the solid electrolyte membrane and the positive electrode. It possesses excellent overall performance.

[0106] The formation process provided in the fourth aspect of this application is implemented in the following detailed manner: First, a clamping pressure of 5MPa to 50MPa is applied, exemplarily 50MPa; second, multiple shallow charge-discharge cycles are performed at a current of 0.1C to 0.5C in an environment of 50℃ to 80℃ to achieve refined and uniform alloy particles; third, densification is carried out at an isostatic pressure of 300MPa to 600MPa in an environment of 80℃ to 100℃, exemplarily 600MPa / 80℃ or 400MPa / 100℃; fourth, a clamping pressure of 5MPa to 50MPa is applied again (exemplarily 50MPa), and the battery is charged at 0.1C to 100% SOC to complete the formation. This process can significantly optimize the negative electrode interface and structure, enhancing battery performance.

[0107] In the above implementation process, the solid-state battery provided in the embodiments of this application includes the solid-state battery anode provided in the first and second aspects and the formation process provided in the fourth aspect. The solid-state battery anode has low porosity and interfacial gap, and has high rate performance, which can improve the electrochemical performance of the solid-state battery such as charge and discharge.

[0108] The technical solution of this application will be further verified below with reference to specific embodiments.

[0109] Example 1

[0110] This embodiment illustrates the basic composition and core parameters of the solid-state battery anode of the present invention.

[0111] A solid-state battery negative electrode includes:

[0112] Anode material: Silicon-carbon composite material.

[0113] Nano-alloy particles: Tin (Sn) alloy particles.

[0114] Key parameters:

[0115] Mass ratio: The mass ratio of nano-alloy particles to the negative electrode material is 1:5.

[0116] Material properties: The Young's modulus of the nano-alloy particles is 40 GPa (≤70 GPa), and the lithium-ion diffusion coefficient is 10⁻. 7 cm² / s (≥10⁻¹²cm² / s).

[0117] Particle size distribution:

[0118] The negative electrode material has a D50 of 5μm and a D90 of 12.5μm, with a D50 to D90 ratio of 1:2.5 (within the range of 1:1.25 to 5).

[0119] The nano-alloy particles have a D50 of 0.5 μm and a D90 of 0.545 μm, with a D50 to D90 ratio of 1:1.09 (within the range of 1:1 to 1.1).

[0120] The ratio of nano-alloy particles D50 to the negative electrode material D50 is 1:10 (within the range of 1:10~20).

[0121] Its preparation method and formation process are as follows:

[0122] (1) First, put 100g of silicon-carbon anode powder (D50=5μm, D90=12.5μm, the ratio of D50 to D90 is 1:2.5) into a ball mill jar, and weigh 20g of tin nano-alloy particles (D50=0.5μm, D90=0.545μm, the ratio of D50 to D90 is 1:1.09) into a ball mill jar. The mass ratio of nano-alloy particles to silicon-carbon anode powder is 1:5, and the ratio of D50 of nano-alloy particles to D50 of silicon-carbon anode powder is 1:10. Mix at 200rpm for 1h to obtain primary silicon-carbon alloy mixture.

[0123] (2) The primary silicon-carbon alloy mixture, sulfide solid electrolyte and binder are added to the homogenizing tank in sequence, with masses of 120g, 22.5g and 7.5g respectively (mass ratio of 80:15:5). Then xylene solvent is added and the solid content is adjusted to a suitable level to prepare a slurry.

[0124] (3) The slurry is coated onto the copper foil current collector, dried, and rolled to obtain the negative electrode sheet.

[0125] (4) The negative electrode, sulfide electrolyte membrane and positive electrode prepared above are stacked and assembled into a solid soft pack battery, and then isostatically densified.

[0126] (5) Place the battery in the clamp and apply a pressure of 50 MPa. Then place it in an environment of 80°C and charge and discharge it multiple times at 0.1C. The states of charge are 20%, 50%, 80% and 100%, respectively. Remove the battery and place it in an isostatic pressure device with an isostatic pressure of 80°C and an isostatic pressure of 600 MPa.

[0127] (6) Fix the isostatically pressed battery in the fixture and apply a pressure of 50 MPa. Charge it at a constant current of 0.1C to 100% SOC to complete battery formation.

[0128] After isostatic pressing, the battery is fixed in a fixture and subjected to a pressure of 50 MPa. It is then charged at a constant current of 0.1C to 100% SOC to complete battery formation.

[0129] Example 2

[0130] Example 2 provides a solid-state battery anode, which differs from Example 1 in that the ratio of D50 to D90 of the anode main material is 1:10, while the other parameters and steps are the same as in Example 1.

[0131] Example 3

[0132] Example 3 provides a solid-state battery anode, which differs from Example 1 in that the ratio of D50 to D90 of the nano-alloy particles is 1:5, while the other parameters and steps are the same as in Example 1.

[0133] Example 4

[0134] Example 4 provides a solid-state battery anode, which differs from Example 1 in that the ratio of the D50 of the nano-alloy particles to the D50 of the anode main material 101 is 1:50.

[0135] Example 5

[0136] Example 5 provides a solid-state battery anode, which differs from Example 1 in that the mass ratio of the anode main material to the nano-alloy particles is 1:0.5.

[0137] Example 6

[0138] Example 6 provides a solid-state battery anode, which differs from Example 1 in that the nano-alloy particles are tungsten powder (Young's modulus is 411 GPa).

[0139] Comparative Example 1

[0140] Comparative Example 1 provides a solid-state battery negative electrode, which differs from Example 1 in that steps (5) and (6) are not performed, i.e. no formation process is performed.

[0141] Comparative Example 2

[0142] Comparative Example 2 provides a solid-state battery anode, which differs from Example 1 in that it does not add nano-alloy particles, but only uses silicon-carbon anode powder as the main anode material.

[0143] The performance of the all-solid-state batteries prepared in the above embodiments and comparative examples was tested, and the test results are shown in Table 1 below:

[0144] Table 1

[0145]

[0146] Results analysis:

[0147] 1. Comparing Examples 1-6, it can be seen that the solid-state battery anode provided in this application has the lowest internal porosity (5%). This is due to its optimal particle size parameter combination (main material D50:D90=1:2.5, alloy particles D50:D90=1:1.09, and the ratio of D50 between the two is 1:10). The low porosity constructs an efficient ion transport network, enabling it to achieve a 0.1C discharge specific capacity of 2203mAh / g, a 1C rate capacity retention of 87% (1916 / 2203), and a 500-cycle capacity retention of 85%, resulting in the best overall performance.

[0148] 2. Comparing Examples 1 and 5, it can be seen that when the proportion of nano-alloy particles is too high (mass ratio 1:3), although the porosity is low (6%), the alloy particles occupy the space of the main material, causing the 0.1C discharge specific capacity to drop to 1250 mAh / g. This proves that a mass ratio of 1:5 is the optimal balance point between capacity and density.

[0149] 3. Comparing Example 1 and Comparative Example 1, it can be seen that, compared with the unformed solid-state battery anode, the solid-state battery anode provided by this application can further refine the uniform nano-alloy particles through the formation process, reducing the porosity from 10% to 5%, and significantly improving the discharge specific capacity and cycle stability. This verifies the necessity of the formation process.

[0150] 4. Comparing Example 1 and Comparative Example 2, it can be seen that the addition of nano-alloy particles to the solid-state battery anode provided in this application reduces the porosity from 25% to 5%, significantly improving discharge capacity, rate performance, and cycle stability. This demonstrates the enhancing effect of nano-alloy particles on anode performance.

[0151] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A solid-state battery negative electrode, characterized in that, The anode material includes a negative electrode substrate and nano-alloy particles composited on the surface or interface of the negative electrode substrate; the mass ratio of the nano-alloy particles to the negative electrode substrate is 1:2~5, the Young's modulus of the nano-alloy particles is ≤70GPa, and the lithium-ion diffusion coefficient of the nano-alloy particles is ≥ cm² / s; the ratio of D50 to D90 of the nano-alloy particles is 1:1 to 1.1, the ratio of D50 to D90 of the negative electrode material is 1:1.25 to 5, and the ratio of D50 of the nano-alloy particles to D50 of the negative electrode material is 1:10 to 20; the negative electrode material is selected from one or more of graphite, silicon-carbon, silicon-oxygen-carbon, and silicon; the nano-alloy particles are selected from a variety of magnesium, aluminum, indium, silver, tin, and germanium.

2. The solid-state battery negative electrode according to claim 1, characterized in that, The nano-alloy particles have a D50 of 0.1~1μm; the negative electrode material has a D50 of 1~20μm and a D90 of 1~25μm.

3. A method for preparing a solid-state battery negative electrode sheet as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Premixing: The negative electrode material and nano-alloy particles are mechanically mixed to obtain a primary composite material; S2. Slurry preparation and molding: The primary composite material, solid electrolyte and binder are mixed to form a slurry, which is then coated, dried and rolled to obtain the negative electrode sheet.

4. The method for preparing the negative electrode sheet of a solid-state battery according to claim 3, characterized in that, In step S1, the mechanical mixing method is at least one of ball milling, airflow mixing, sand milling, or ultrasonic vibration.

5. The method for preparing the negative electrode sheet of a solid-state battery according to claim 4, characterized in that, In step S2, the mass ratio of the primary composite material, solid electrolyte, and binder is (50-80):(5-20):(1-5); The solid electrolyte is at least one of sulfide solid electrolyte, halide solid electrolyte, or oxide solid electrolyte; The adhesive is at least one of polyvinylidene fluoride, polystyrene, polyisobutylene, styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, polyacrylic acid, or carboxymethyl cellulose.

6. A solid-state battery, characterized in that, Includes a solid-state battery negative electrode as described in any one of claims 1-2 or a negative electrode sheet prepared by the preparation method described in any one of claims 3-5.

7. A formation process suitable for solid-state batteries as described in claim 6, characterized in that, Includes the following steps: P1, Pressure Pre-tightening: Applying an initial pressure of 5~50MPa to the assembled and densified solid-state battery; P2, Stepped activation: At an ambient temperature T1 of 50~80℃, the battery is subjected to stepped charge-discharge cycles at a current of 0.1C~0.5C. The state of charge (SOC) steps of the charge-discharge cycles are 20% SOC, 50% SOC, 80% SOC and 100% SOC respectively. The stepped charge-discharge cycle means that at each SOC step, the battery is first charged to the corresponding SOC with a constant current, and then discharged to the same depth of discharge (SOD) with a constant current. P3, Hot Isostatic Press Densification: The battery that has undergone step P2 is treated by applying an isostatic pressure of 300-600 MPa at an ambient temperature T2 of 80-100℃. P4, Final Formation: The battery that has passed through step P3 is subjected to a pressure of 5~50MPa again and charged to 100% SOC with a constant current of 0.1C.

Images