Composite negative electrode electrolyte sheet, preparation method thereof and solid-state battery

The invention provides a composite negative electrode electrolyte sheet, a preparation method thereof and a solid-state battery, and belongs to the technical field of solid-state batteries. The preparation method of the composite negative electrode electrolyte sheet comprises the following steps: pre-pressing and molding first solid electrolyte powder to obtain a sheet-shaped object; covering the powder mixture on one surface in the thickness direction of the sheet-shaped object to obtain a precursor; and carrying out hot pressing treatment on the precursor. The powder mixture comprises graphene, a second solid electrolyte and a conductive agent; the first solid electrolyte and the second solid electrolyte are made of the same material; the pressure applying direction during hot pressing treatment is the thickness direction of the sheet-shaped object. According to the composite negative electrode electrolyte sheet, the solid electrolyte and the graphene negative electrode are tightly combined, and the solid e