Lithium secondary battery and method for manufacturing the same

摘要

Provided is a lithium secondary battery in which negative-electrode active material particles containing silicon and/or a silicon alloy are used and which prevents the occurrence of breakage of a binder itself and peel-off of the binder at the interfaces with the negative-electrode active material and the negative-electrode current collector and has a high energy density and an excellent cycle characteristic. The lithium secondary battery includes: a negative electrode in which a negative-electrode active material layer including negative-electrode active material particles containing silicon and/or a silicon alloy and a binder is formed on a surface of electrically conductive metal foil serving as a negative-electrode current collector; a positive electrode; and a nonaqueous electrolyte, wherein the binder contains a polyimide resin including a crosslinked structure formed by imidization of a hexavalent or higher-valent carboxylic acid or an anhydride thereof with a diamine.

主权项

1. A lithium secondary battery including: a negative electrode in which a negative-electrode active material layer including negative-electrode active material particles containing silicon and/or a silicon alloy and a binder is formed on a surface of electrically conductive metal foil serving as a negative-electrode current collector; a positive electrode; and a nonaqueous electrolyte,
wherein the binder comprises a polyimide resin comprising a crosslinked structure formed by imidization of an anhydride represented by Chem. 1 below with a diamine represented by Chem. 2 below; wherein the crosslinked structure comprises a structure represented by Chem. 3 below; and wherein the polyimide resin comprising the crosslinked structure comprises a linear chain structure represented by Chem. 6 below and/or Chem. 7 below and formed by imidization of a tetracarboxylic dianhydride represented by Chem. 4 below and/or Chem. 5 below with the diamine represented by Chem. 2 above: