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CN-121983649-A - Composite solid electrolyte membrane, preparation method thereof and solid battery

CN121983649ACN 121983649 ACN121983649 ACN 121983649ACN-121983649-A

Abstract

The embodiment of the application provides a composite solid electrolyte membrane, a preparation method thereof and a solid battery. The composite solid electrolyte membrane comprises a first electrolyte membrane, a second electrolyte membrane and a third electrolyte membrane which are sequentially stacked, wherein the first electrolyte membrane comprises a first solid electrolyte with D50 being A1, the second electrolyte membrane comprises a second solid electrolyte with D50 being A2, the third electrolyte membrane comprises a third solid electrolyte with D50 being A3, both A1 and A3 are larger than A2, the content of the first solid electrolyte in the first electrolyte membrane is denoted as W1, the content of the second solid electrolyte in the second electrolyte membrane is denoted as W2, and the content of the third solid electrolyte in the third electrolyte membrane is denoted as W3, and W1 is more than W2 and more than W3. The application solves the problem of poor electrical property and cycle property of the sulfide solid-state battery by means of gradient optimization of the solid-state electrolyte content and control of the solid-state electrolyte particle diameter relationship.

Inventors

  • ZHANG DINGYU
  • SU HANG
  • FU FANG
  • DONG JIE
  • XU TENG

Assignees

  • 奇瑞汽车股份有限公司

Dates

Publication Date
20260505
Application Date
20260127

Claims (10)

  1. 1. A composite solid electrolyte membrane is characterized by comprising a first electrolyte membrane (10), a second electrolyte membrane (20) and a third electrolyte membrane (30) which are sequentially laminated, The first electrolyte membrane (10) comprises a first solid electrolyte with D50 being A1, the second electrolyte membrane (20) comprises a second solid electrolyte with D50 being A2, the third electrolyte membrane (30) comprises a third solid electrolyte with D50 being A3, and both A1 and A3 are larger than A2; The content of the first solid electrolyte in the first electrolyte membrane (10) is denoted as W1, the content of the second solid electrolyte in the second electrolyte membrane (20) is denoted as W2, and the content of the third solid electrolyte in the third electrolyte membrane (30) is denoted as W3, W1> W2> W3.
  2. 2. The composite solid electrolyte membrane according to claim 1, wherein the first electrolyte membrane (10) further comprises a first binder, the second electrolyte membrane (20) further comprises a second binder, the third electrolyte membrane (30) further comprises a third binder, and: in the first electrolyte membrane (10), the weight ratio of the first solid electrolyte to the first binder is (90-99): 1-10; in the second electrolyte membrane (20), the weight ratio of the second solid electrolyte to the second binder is (70-80): 20-30; in the third electrolyte membrane (30), the weight ratio of the third solid electrolyte to the third binder is (40-50) (50-60).
  3. 3. The composite solid electrolyte membrane according to claim 1 or 2, wherein, In the first electrolyte membrane (10), the D50 of the first solid electrolyte is 3-5 mu m; In the second electrolyte membrane (20), the D50 of the second solid electrolyte is 500 nm-1 μm; in the third electrolyte membrane (30), the D50 of the third solid electrolyte is 3-5 [ mu ] m.
  4. 4. A composite solid electrolyte membrane according to any one of claim 1 to 3, wherein, The first solid electrolyte and the third solid electrolyte are first sulfide electrolytes; the second solid electrolyte is selected from at least one of a second sulfide electrolyte, an oxide electrolyte, and a halide electrolyte.
  5. 5. The composite solid electrolyte membrane according to any one of claim 1 to 4, wherein, W1 is (18-20): (15-16): (4-10) W2 is W3; A1, A2, A3 is (8~4) 1 (8~4).
  6. 6. The composite solid electrolyte membrane according to any one of claims 1 to 5, wherein the thickness of the composite solid electrolyte membrane is 30±2 μm, and wherein the ratio of the thicknesses of the first electrolyte membrane (10), the second electrolyte membrane (20), and the third electrolyte membrane (30) is (0.7 to 0.8): 1 (0.7 to 0.8).
  7. 7. A method for producing the composite solid electrolyte membrane according to any one of claims 1 to 6, comprising: step S1, preparing the first solid electrolyte, the second solid electrolyte and the third solid electrolyte into a first slurry, a second slurry and a third slurry respectively; And S2, preparing the first slurry, the second slurry and the third slurry into composite film layers through coating treatment, wherein the composite film layers comprise a first film layer, a second film layer and a third film layer which are sequentially laminated, and the composite film layers are sequentially dried and rolled to obtain the composite solid electrolyte membrane.
  8. 8. The method for producing a composite solid electrolyte membrane according to claim 7, wherein, in the step S1, The solid content of the first slurry, the second slurry and the third slurry is 40% -60% respectively and independently; The first slurry, the second slurry, and the third slurry each independently use at least one of butyl butyrate, butyl isobutyrate, anisole, toluene, paraxylene, n-heptane, methylene chloride, dichloroethane, dichloropropane, dibromomethane, dibromoethane, dibromopropane, and cyclohexane as a solvent.
  9. 9. The method for producing a composite solid electrolyte membrane according to claim 7, wherein, in the step S2, The drying comprises a first stage with the temperature of 50+/-5 ℃ and a second stage with the temperature of 80+/-5 ℃ which are sequentially carried out; The rolling is performed under the condition that the rolling pressure is 5+/-0.5 MPa.
  10. 10. A solid state battery comprising a positive electrode membrane, a negative electrode membrane, and an electrolyte membrane, characterized in that the electrolyte membrane is the composite solid state electrolyte membrane according to any one of claims 1 to 6, and the first electrolyte membrane (10) in the composite solid state electrolyte membrane is disposed opposite to the positive electrode membrane, and the third electrolyte membrane (30) is disposed opposite to the negative electrode membrane.

Description

Composite solid electrolyte membrane, preparation method thereof and solid battery Technical Field The embodiment of the application relates to the field of solid-state batteries, in particular to a composite solid electrolyte membrane, a preparation method thereof and a solid-state battery. Background All-solid-state batteries are the next generation energy storage technology, whose performance core depends on the choice of solid electrolyte materials. Among three major classes of solid state electrolytes, oxide, polymer and sulfide, sulfide solid state electrolytes, particularly Li 6PS5 X (x=cl, br, I) materials, are considered as one of the most potential paths to achieve high energy density, high power density all solid state batteries because of their highest room temperature ion conductivity (10 -3~10-2 S·cm-1) among all solid state electrolytes. Based on the great advantage of sulfide solid electrolyte in electrochemical performance, the film forming technology becomes the key of industrialization. Wet processes are widely studied because of their ease of achieving large area, continuous production. However, the prior art generally uses a single sulfide solid electrolyte membrane, such as Li 6PS5 Cl (LPSC), mixed with a small amount of binder to coat the substrate with a film. However, the electrolyte membrane prepared by the method has the problems of poor mechanical strength, poor compatibility with an electrode interface and the like, and is difficult to directly release the membrane and is applied to a lamination process of a soft package battery. In summary, although sulfide solid electrolyte materials show outstanding ionic conductivity, the preparation method and performance regulation of the solid electrolyte membrane in the prior art still have obvious defects that firstly, the contradiction between mechanical properties and electrochemical properties is that the flexibility and strength of the membrane can be enhanced by increasing the content of a binder, but the ionic conductivity can be seriously sacrificed, the brittleness of the membrane can be increased by decreasing the content of the binder, the membrane can not be taken off and laminated, secondly, the interface problem is outstanding, for example, the homogeneous single-layer electrolyte membrane is difficult to simultaneously consider the interface stability and compatibility with anode and cathode materials, and thirdly, the process compatibility is poor, the electrolyte membrane prepared by the prior method often needs to depend on a carrier, can not form a self-supporting membrane, is difficult to cut and laminated like the traditional membrane, and the application of the electrolyte membrane in a soft package battery is limited. That is, the solid electrolyte membrane in the prior art has the problem that it is difficult to combine mechanical properties and electrochemical properties, and also has a serious interface problem, so that it is difficult to provide stable support for the electrical properties and cycle properties of the solid battery. There is currently no good solution to the above problems. Disclosure of Invention The embodiment of the application provides a composite solid electrolyte membrane, a preparation method thereof and a solid battery, which at least solve the technical problems that the interface performance of the solid electrolyte membrane in the prior art is poor, and the mechanical performance and the electrochemical performance are difficult to balance, so that the electrical performance and the cycle performance of the solid battery are poor. According to a first aspect of the embodiment of the present application, there is provided a composite solid electrolyte membrane comprising a first electrolyte membrane, a second electrolyte membrane and a third electrolyte membrane laminated in this order, wherein the first electrolyte membrane comprises a first solid electrolyte with D50 being A1, the second electrolyte membrane comprises a second solid electrolyte with D50 being A2, the third electrolyte membrane comprises a third solid electrolyte with D50 being A3, both A1 and A3 are larger than A2, the content of the first solid electrolyte in the first electrolyte membrane is denoted as W1, the content of the second solid electrolyte in the second electrolyte membrane is denoted as W2, and the content of the third solid electrolyte in the third electrolyte membrane is denoted as W3, W1> W2> W3. The first electrolyte membrane further comprises a first binder, the second electrolyte membrane further comprises a second binder, the third electrolyte membrane further comprises a third binder, the weight ratio of the first solid electrolyte to the first binder in the first electrolyte membrane is (90-99): 1-10, the weight ratio of the second solid electrolyte to the second binder in the second electrolyte membrane is (70-80): 20-30), and the weight ratio of the third solid electrolyte to the third binder