Abstract: A method for forming an electrode for a lithium ion battery is disclosed. The method includes preparing a mixture slurry, coating the mixture slurry onto a current collector body, and heating the mixture slurry coating to form an active substance layer. The slurry mixture can be prepared by mixing a polyimide precursor solution and active substance particles. The polyimide resin in the active substance layer is porous due to the method.

Abstract: The invention addresses the problem of providing a polyimide precursor, a polyimide precursor solution, and a mixture slurry, each capable of more firmly binding active material particles to a current collecting body. The polyimide precursor solution according to the invention contains a tetracarboxylic acid ester compound, a diamine compound having an anionic group, and a solvent. The solvent dissolves the tetracarboxylic acid ester compound and the diamine compound. As the tetracarboxylic acid ester compound, a 3,3?,4,4?-benzophenonetetracarboxylic acid diester is particularly preferred. Examples of the “diamine compound having an anionic group” include 3,4-diaminobenzoic acid, 3,5-diaminobenzoic acid, and m-phenylenediamine-4-sulfonic acid. Further, the mixture slurry according to the invention contains active material particles in the polyimide precursor solution.