Composite positive electrode material, composite positive electrode plate, all-solid-state battery and preparation method

The invention relates to a composite positive electrode material, a composite positive electrode plate, an all-solid-state battery and a preparation method. The composite positive electrode material is formed by compounding a positive electrode active material and a polymer electrolyte, wherein the surface of the positive electrode active material is coated with an oxide fast ion conductor. The composite positive pole piece comprises the composite positive pole material. The preparation method of the composite positive pole piece comprises the following steps: placing an oxide fast ion conductor and a positive active material in a solvent, carrying out ball milling and sintering, then mixing with a polymer electrolyte, and then mixing with a conductive agent and an adhesive to obtain positive slurry; and coating a current collector with the positive electrode slurry to obtain the composite positive electrode plate. The all-solid-state battery comprises a composite positive pole piece, a negative pole piece an