Composite electrolyte and solid-state battery containing same

A composite electrolyte, including a sulfide electrolyte, a polymer electrolyte, and a functional additive material are provided. In some embodiments, the functional additive material is selected from polymers represented by the following structural R1-O-R2-A. In some embodiments, R1 is selected from at least one of polyvinyl group, polypropylene group, polyacrylate group, polyvinylcarbonate group, polyacrylonitrile group, and polystyrene group; R2 is a straight-chain or branched alkyl group with 3-10 carbon atoms; A is selected from at least one aromatic hydrocarbon group of benzene group, biphenyl group, triphenyl group, naphthalene group, anthracene group, phenanthrene group, and pyrene group; and X is selected from at least one of hydrogen atom, halogen atom, mercapto group, hydroxyl group, amine group, and aldehyde group.