摘要 |
PURPOSE:To increase a battery life and manufacturing efficiency by cleaning the surface of copper or copper alloy, which is to be in contact with a negative mass, of a negative current collector with a chemical polishing solution of hydtogen peroxide and sulfuric acid family containing a rust preventive, and applying rust preventing treatment on the surface at the same time. CONSTITUTION:A reverse curl portion 5 of the circumference of a negative case 1 is covered with a synthetic resin jig 6. This case is treated with a chemical polishing solution that the molar ratio of sulfuric acid to hydrogen peroxide is 0.045 and about 0.2% of benzotriazole is contained as a rust preventive for about 2min at room temperature. Then the case is washed with water, washed with a solution containing sulfuric acid, washed with water, neutralized, and washed with water again. By this treatment, the exposed surface of copper is polished chemically and harmful foreign matter is removed and at the same time a rust preventing film is formed on the cleaned surface. |