CN-122025771-A - Composite solid electrolyte membrane, preparation method thereof and solid battery

CN122025771ACN 122025771 ACN122025771 ACN 122025771ACN-122025771-A

Abstract

The application discloses a composite solid electrolyte membrane, a preparation method thereof and a solid battery. The composite solid electrolyte membrane comprises a first solid polymer electrolyte layer, a second solid polymer electrolyte layer positioned on the first solid polymer electrolyte layer and a third solid polymer electrolyte layer positioned on the second solid polymer electrolyte layer, wherein the first solid polymer electrolyte layer, the second solid polymer electrolyte layer and the third solid polymer electrolyte layer all contain carbon nanofibers, and the carbon nanofiber content in the first solid polymer electrolyte layer and the third solid polymer electrolyte layer is higher than the carbon nanofiber content in the second solid polymer electrolyte layer. According to the application, the high-strength carbon nanofiber network structure is introduced to prepare the composite solid electrolyte membrane with a multilayer structure, so that the tensile strength and the impact resistance of the electrolyte membrane can be improved, and the structural stability in the battery cycle process is ensured.

Inventors

ZHOU YANYAN
GAO XINGYU
GUO JIE
MA SHUHUI
WANG YANG
YU HONGJIANG
YU ZHEXUN

Assignees

江苏正力新能电池技术股份有限公司

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (10)

1. A composite solid electrolyte membrane comprising a first solid polymer electrolyte layer, a second solid polymer electrolyte layer on the first solid polymer electrolyte layer, and a third solid polymer electrolyte layer on the second solid polymer electrolyte layer; The first solid polymer electrolyte layer, the second solid polymer electrolyte layer and the third solid polymer electrolyte layer all contain carbon nanofibers, and the carbon nanofiber content in the first solid polymer electrolyte layer and the third solid polymer electrolyte layer is higher than the carbon nanofiber content in the second solid polymer electrolyte layer.
2. The composite solid electrolyte membrane according to claim 1, wherein the ratio of the carbon nanofibers in the first solid polymer electrolyte layer, the second solid polymer electrolyte layer, and the third solid polymer electrolyte layer is 5-15:1-3:5-15.
3. The composite solid electrolyte membrane of claim 1 wherein the carbon nanofiber surface has hydroxyl and/or carboxyl functional groups.
4. The composite solid electrolyte membrane of claim 1 wherein the polymer electrolyte in the first solid polymer electrolyte layer, the second solid polymer electrolyte layer, and the third solid polymer electrolyte layer is polyethylene oxide.
5. The composite solid electrolyte membrane according to claim 1, wherein the total thickness of the composite solid electrolyte membrane is 50-200 μm, the thickness of the second solid polymer electrolyte layer is 40-60% of the total thickness, the thicknesses of the first solid polymer electrolyte layer and the third solid polymer electrolyte layer are 20-30% of the total thickness, respectively, and the ratio of the thicknesses of the layers satisfies the total = 100%.
6. A method for producing the composite solid electrolyte membrane according to any one of claims 1 to 5, comprising the steps of: S1, respectively mixing modified carbon nanofibers with a polymer electrolyte solution to prepare a first solid polymer electrolyte mixed solution, a second solid polymer electrolyte mixed solution and a third solid polymer electrolyte mixed solution, wherein the carbon nanofiber content in the first solid polymer electrolyte mixed solution and the third solid polymer electrolyte mixed solution is higher than the carbon nanofiber content in the second solid polymer electrolyte mixed solution; s2, coating and drying the first solid polymer electrolyte mixed solution, the second solid polymer electrolyte mixed solution and the third solid polymer electrolyte mixed solution in sequence to obtain a multilayer structure; S3, carrying out hot pressing treatment on the multilayer structure to obtain the composite solid electrolyte membrane.
7. The method of claim 6, wherein the modified carbon nanofiber is prepared by one or both of the following methods: A. acid treatment, namely reacting the carbon nanofiber with an acid solution to obtain a modified carbon nanofiber with the surface containing carboxylic acid groups; B. And (3) performing plasma treatment on the carbon nanofiber in an atmosphere containing an argon/oxygen mixed gas to obtain the modified carbon nanofiber containing the surface functional groups of the hydroxyl and the carboxyl.
8. The method according to claim 7, wherein in the method A, the acid solution contains at least one of sulfuric acid, nitric acid and hydrochloric acid at a concentration of 0.1-2M, and the reaction temperature of the carbon nanofibers and the acid solution is 60-80 ℃ for 2-6 hours.
9. The method according to claim 7, wherein in the method B, the ratio of the argon to the oxygen is 1:1-3:1 by volume, the power of the plasma treatment is 50-150W, the pressure is 0.5-2Pa, and the treatment time is 5-15 minutes.
10. A solid-state battery comprising the composite solid electrolyte membrane according to any one of claims 1 to 5, or the composite solid electrolyte membrane produced by the production method according to any one of claims 6 to 9.

Description

Composite solid electrolyte membrane, preparation method thereof and solid battery Technical Field The application belongs to the technical field of solid-state batteries, and particularly relates to a composite solid electrolyte membrane, a preparation method thereof and a solid-state battery. Background The solid-state lithium battery adopts the solid electrolyte to replace the traditional liquid electrolyte, is hopeful to fundamentally solve the safety problem of the battery and realize higher energy density. Among the many solid electrolyte systems, polyethylene oxide (PEO) based polymer electrolytes have been of great interest due to their good interfacial contact with electrodes, flexibility, and ease of processing. However, PEO-based electrolytes themselves suffer from low ionic conductivity at room temperature, insufficient mechanical strength (especially poor creep resistance at high temperatures), limited ability to suppress lithium dendrites, and the like, severely restricting their use in high power, long life solid state batteries. To improve the performance of PEO-based electrolytes, complex modifications are commonly made in the prior art by blending, copolymerizing or adding inorganic fillers. The incorporation of inorganic fillers (e.g., oxide ceramic particles) is an effective way to increase ionic conductivity and mechanical modulus. However, simple mechanical blending often results in uneven dispersion of the filler in the polymer matrix, easy agglomeration, not only does not form an effective ion continuous transmission path, but may introduce additional resistance due to interfacial defects. Meanwhile, the interface compatibility between the ceramic particles and the polymer matrix is poor, and in the long-term cycle process of the battery, the interface is easy to be debonded or cracked due to the volume change or thermal stress of the electrode, so that the interface impedance is rapidly increased, and the performance of the battery is rapidly attenuated. To build a more stable ion transport network and strengthen the electrolyte structure, researchers have begun to explore one-dimensional nanomaterials as reinforcements. For example, chinese patent document CN116826159a discloses a method for preparing a composite solid electrolyte with soft filler, which converts nano cellulose particles into lithiated cellulose, and then mixes solvent, polymer, lithium salt and lithiated cellulose to obtain the composite solid electrolyte, aiming at improving the transportation efficiency of lithium ions in the composite solid electrolyte by utilizing the characteristic that lithiated cellulose has a plurality of oxygen-containing groups. The technology focuses on improving the overall conductivity by utilizing the high conductivity of the lithiated cellulose, but the description on how to synchronously solve the systematic problems of macroscopic mechanical strength of an electrolyte membrane, interface stability with an electrode, inhibition of lithium dendrite growth and the like through structural design is insufficient. On the other hand, there have been studies on attempts to improve the interfacial compatibility of solid-state batteries by means of sub-nano-sized inorganic fillers. Chinese patent document CN120319900a discloses a method for constructing a polyethylene oxide based composite solid electrolyte by sub-nanowires, which optimizes ion transport and interfacial compatibility by graft modifying the surface of sub-nanowires and applying it to construct a composite solid electrolyte. However, this approach may face a large interfacial resistance during ion interlayer transport. In summary, in the prior art, it is difficult to ensure excellent mechanical strength and interfacial stability while improving ion conductivity, or to achieve seamless joining of ion transport paths and gradient transition of mechanical properties although a multilayer structure is employed. Therefore, developing a composite solid electrolyte membrane with high ion mobility, high mechanical strength, excellent interface stability and structural integrity is of great significance for promoting the practical application of high-performance solid batteries. Disclosure of Invention The application aims to provide a composite solid electrolyte membrane, a preparation method thereof and a solid battery. In order to achieve the above purpose, the technical scheme of the application is as follows: In a first aspect, the present application provides a composite solid electrolyte membrane comprising a first solid polymer electrolyte layer, a second solid polymer electrolyte layer on the first solid polymer electrolyte layer, and a third solid polymer electrolyte layer on the second solid polymer electrolyte layer; Wherein the first solid polymer electrolyte layer, the second solid polymer electrolyte layer and the third solid polymer electrolyte layer each contain Carbon Nanofibers (CNF), and the carbon nanofiber conten