▎ 摘　　要

NOVELTY - Branched cross-linked polyamic acid solution comprises polyamic acid molecular chain with strong polar groups, where the entire molecular chain is in branched and cross-linked form, the strongly polar group is at least one of hydroxy group, carboxy group, sulfonic acid group, trifluoromethyl group, and cyano group, the solid content of the polyamic acid solution is 0.5-50 wt.%, and the intrinsic viscosity is 0.1-6.63 dl/g. USE - The branched cross-linked polyamic acid solution is useful for preparing polyimide adhesive used in electrode material for lithium-ion battery, and also useful in portable electronic device, power automobile, energy storage power station and electric tool field. ADVANTAGE - The branched cross-linked polyamic acid solution has strong polarity, stronger adhesive force, stronger interaction, better adhesive performance and coating performance, and more uniformly dispers slurry. The lithium-ion battery assembled using the polyimide adhesive has good cycle performance, multiplying power performance and safety performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: preparation method of branched cross-linked polyamic acid solution, comprising (1) carrying out polycondensation reaction on dibasic acid anhydride and dibasic amine in polar solvent, obtaining linear polyamic acid solution, where the diamine comprises common diamine and functional diamine, and (2) adding polyamine into the linear polyamic acid solution, and reacting to obtain branched and cross-linked polyamic acid solution; preparation method of polyimide adhesive, comprising (i) preparing branched cross-linked polyamic acid solution, (ii) fully mixing the anode active material or cathode active material, conductive agent, branched cross-linked polyamic acid solution and polar solvent, and stirring evenly to obtain electrode slurry, and (iii) uniformly coating the electrode slurry on the current collector, drying and rolling, and thermally treating to obtain polyimide binder on the lithium-ion battery pole piece; polyimide adhesive, comprising polyimide molecular chain in the polyimide adhesive comprising strong polar groups, where the entire molecular chain is in branched and cross-linked form, where the strongly polar group is at least one of hydroxy group, carboxy group, sulfonic acid group, trifluoromethyl group and cyano group; and lithium-ion battery pole piece, comprising polyimide adhesive, comprising lithium-ion battery pole piece composed of an active material layer and a current collector, where the active material layer is composed of anode active material or cathode active material, conductive agent and polyimide adhesive, the mass percentage of each component of the active material layer is 80-98 wt.% of the anode or cathode active material, conductive agent is 1-10 wt.%, and polyimide adhesive is 1-10 wt.%.