The invention provides a flexible composite
solid-state
electrolyte, a full-
solid-state
lithium-
ion battery and a preparation method thereof. The
solid-
phase mixing of a
sulfide solid-state
electrolyte or a modifier thereof, a
thermoplastic polymer or a modifier thereof and
lithium salt enables the composite solid-state
electrolyte to have good flexibility while improving the dispersion uniformityand effective contact of each component. A
halide,
phosphate and / or an
oxide are added to the
sulfide material especially before the composition of the
sulfide solid-state electrolyte and the polymersolid-state electrolyte, thereby providing a multi-dimensional channel for
lithium ion transmission, increasing the disordered degree of lithium
ion distribution, and being capable of further improving the lithium ion
conductivity and electrochemical stability of the composite solid-state electrolyte. The flexible
composite electrolyte has the advantages of high lithium
conductivity at the
room temperature, good electrochemical stability, easy preparation and
processing, ability of being bent and
cut and the like. The formed flexile full-solid-state battery has good mechanical performance andbending performance, and improves the cycle life and
energy density.