▎ 摘　　要

NOVELTY - Composite coating diaphragm comprises a base film, and at least one side of the base film opposite to the cathode pole piece film is provided with polymethylmethacrylate (PMMA) coating layer. The PMMA coating layer comprises PMMA and conductive carbon material. The composite coating diaphragm further comprises a pre-coated inorganic film. The pre-coated inorganic film is set between the base film and the PMMA coating layer. USE - Composite coating diaphragm for lithium ion battery. ADVANTAGE - Composite coating diaphragm improves the cycle performance and safety performance of the battery, can induce the reaction of lithium ions, inducing lithium deposition, reduces the current density on the surface of the cathode and prevents the appearance of lithium dendrites. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the preparation method of composite coating membrane. DESCRIPTION OF DRAWING(S) - The drawing shows a structure schematic diagram of the composite coating diaphragm. 1Base film 2Pre-coating inorganic film 3Pmma coating layer 31Conductive carbon material