The invention belongs to the field of
lithium ion batteries, and particularly relates to a semi-
solid lithium battery diaphragm and a preparation method thereof.The semi-
solid lithium battery diaphragm comprises a base membrane and gradient functional coatings coated on the two sides of the base membrane, the base membrane is a
polyimide membrane, and each gradient functional
coating comprises a bonding layer on the bottom layer, a regulating layer on the
surface layer and a filling layer located between the bonding layer and the regulating layer; the bonding layer comprises a component A, and the component A comprises a
polymer matrix, a
disulfide bond-containing cross-linking agent, a
coupling agent and a first
solvent; the
polymer matrix comprises
polyimide and
polyurethane; the filling layer comprises a component B and a component A, and the component B comprises core-shell particles and a dispersing agent, wherein the core-shell particles are formed by
coating Li1. 3Al0. 3Ti1. 7 (PO4) 3 particles with ZrO2; the regulation and
control layer comprises perfluorinated
sulfonic acid resin, a
plasticizer, an interface stabilizer, a second
solvent and deionized water. Through the synergistic effect of all the
layers in the gradient functional
coating, the self-repairing performance of a damaged interface of the diaphragm can be achieved, and the strength of the diaphragm is improved.