CN-122025548-A - Negative electrode plate, preparation method thereof and all-solid-state battery

Abstract

The invention relates to the technical field of batteries, in particular to a negative electrode plate, a preparation method thereof and an all-solid-state battery. The invention provides a negative electrode plate, which comprises a negative electrode active material, a solid electrolyte, a conductive agent and a binder, wherein the solid electrolyte is distributed in the negative electrode plate in a cylindrical form. According to the negative electrode plate, through the design of the specific structure of the negative electrode plate, the high-efficiency utilization of the solid electrolyte is realized, and the higher energy density, the higher multiplying power and the longer cycle performance are realized on the basis of lower addition amount of the solid electrolyte in the negative electrode plate.

Inventors

• ZHANG XI
• WANG YUJIA
• ZHU FEI

Assignees

• 上海屹锂新能源科技有限公司

Dates

Publication Date

20260512

Application Date

20260414

Claims (10)

1. 1. The negative electrode plate is characterized by comprising a negative electrode active material, a solid electrolyte, a conductive agent and a binder; Wherein the solid electrolyte is distributed in the negative electrode plate in a cylindrical form.
2. 2. The negative electrode plate according to claim 1, wherein the negative electrode plate comprises a negative electrode current collector and a negative electrode material layer arranged on the surface of the negative electrode current collector, the negative electrode material layer is provided with a plurality of cylindrical holes penetrating through the negative electrode material layer, and the solid electrolyte is filled in the cylindrical holes.
3. 3. The negative electrode sheet according to claim 1, wherein the mass of the solid electrolyte is 5% -30% of the total mass of the negative electrode active material, the solid electrolyte, the conductive agent and the binder.
4. 4. The negative electrode sheet according to claim 2, wherein the negative electrode sheet satisfies the following relation of 1.5≤D1/D2≤5.0, wherein D1 is the pore diameter of the cylindrical pore in μm, and D2 is the average particle diameter of the solid electrolyte in μm.
5. 5. The negative electrode tab of claim 4, wherein 1.0 μm or less D1 or less 10.0 μm.
6. 6. The negative electrode tab of claim 4, wherein 0.3 μm or less D2 or less 5.0 μm.
7. 7. The negative electrode tab of claim 4, wherein the negative electrode active material comprises at least one of a silicon-carbon composite material, a silicon oxygen material, a micro-silicon material, a porous silicon material, a nano-silicon material, and a hollow silicon material; And/or the solid electrolyte includes at least one of a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, and a polymer solid electrolyte.
8. 8. The negative electrode tab of claim 4, wherein the conductive agent comprises at least one of conductive carbon black, carbon nanotubes, vapor grown carbon fibers, graphene, and carbon quantum dots.
9. 9. The method for preparing the negative electrode sheet according to any one of claims 1 to 8, comprising the steps of: S1, mixing a negative electrode active material, a conductive agent, a binder and a solvent to obtain slurry A, coating the slurry A on a negative electrode current collector, and sequentially drying and rolling to obtain a pole piece substrate; s2, etching cylindrical holes perpendicular to the negative current collector on the pole piece substrate by adopting laser etching; S3, mixing the solid electrolyte, the binder and the solvent to obtain slurry B, coating the slurry B on the etched pole piece substrate, and drying to obtain the negative pole piece.
10. 10. An all-solid-state battery comprising the negative electrode tab of any one of claims 1 to 8.

Description

Negative electrode plate, preparation method thereof and all-solid-state battery Technical Field The invention relates to the technical field of batteries, in particular to a negative electrode plate, a preparation method thereof and an all-solid-state battery. Background All-Solid-state lithium batteries (All-Solid-State Lithium Batteries, ASSLBs) are recognized as a revolutionary technology for breaking potential safety hazards and energy density bottlenecks of traditional liquid electrolyte lithium ion batteries by virtue of the leakage-free and flame-retardant properties of Solid electrolyte and the ultrahigh energy density lifting potential brought by an integrated structure of a positive electrode, an electrolyte and a negative electrode, and have wide application prospects in the fields of electric automobiles, unmanned aerial vehicles and the like. The cathode material is used as a core support of the performance of the all-solid-state battery, and the silicon-based cathode is an ideal candidate material for realizing the aim of high energy density of the all-solid-state battery due to the ultra-high theoretical gram capacity of 4200mAh/g (about 10 times of commercial graphite cathode). However, practical application of silicon-based negative electrodes in all-solid-state batteries is limited by the dual difficulties of solid-solid interface and ion transport. On the one hand, the silicon and the solid electrolyte have obvious chemical-mechanical double incompatibility problems, the Young modulus of the silicon is larger, the volume expansion in the lithiation process is easy to cause the collapse of an electrode structure and the peeling of an interface, meanwhile, the ion conducting capability of the silicon is poorer, and when the electrode reaches a certain thickness, the ion transmission hysteresis effect is obvious, so that larger battery polarization is brought. In order to alleviate the problems, the prior art generally adopts a scheme of directly adding a certain amount of solid electrolyte into a silicon negative electrode sheet formula, and constructs a continuous ion transmission path through the solid electrolyte, and simultaneously improves the solid-solid interface contact state between silicon and the electrolyte, and reduces interface impedance. However, the conventional addition scheme has technical contradiction which is difficult to reconcile, and the improvement of the comprehensive performance of the all-solid-state battery is seriously restricted. First, the solid electrolyte belongs to an inactive substance, and the addition of the solid electrolyte in the negative electrode plate directly reduces the duty ratio of the active substance, so that the energy density of the battery is obviously reduced, which is contrary to the core research and development goal of the high energy density of the all-solid battery. Secondly, when the surface density of the pole piece is increased to improve the energy density of the battery, the thickness of the pole piece is increased, the transmission distance of lithium ions in the pole piece is obviously prolonged, and at the moment, even if solid electrolyte is added, a high-efficiency long-range ion transmission network is difficult to construct, the ion conduction function of the battery cannot be fully exerted, and the multiplying power performance and the cycle stability of the battery are greatly attenuated. Especially under the working condition of high surface density, the ion transmission bottleneck problem is more prominent, and becomes a key pain point for limiting the industrialization process of the silicon-based all-solid-state battery. Therefore, how to further improve the surface density of the pole piece and realize the cooperative improvement of the energy density, the multiplying power performance and the cycle performance of the battery on the premise of reducing the dosage of the solid electrolyte at the negative electrode side becomes a technical problem to be overcome in the current all-solid-state battery field. In view of this, the present invention has been made. Disclosure of Invention The first object of the invention is to provide a negative electrode plate, which realizes the high-efficiency utilization of solid electrolyte by the design of the specific structure of the negative electrode plate, and realizes higher energy density, higher multiplying power and longer cycle performance on the basis of lower addition amount of the solid electrolyte in the negative electrode plate. The second object of the invention is to provide a preparation method of the negative electrode plate. A third object of the present invention is to provide an all-solid battery. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: The invention provides a negative electrode plate, which comprises a negative electrode active material, a solid electrolyte, a conductive age