| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of an internal short circuit of a battery caused by temperature rise in overcharge or abnormality of the battery by forming a thin film of carboxymethylcellulose on the surface of a positive electrode of a secondary battery. SOLUTION: A positive electrode active material LiCoO2, carbon powder acting as a conducting material, and PVDF(polyvinylidene fluoride) aqueous dispersion acting as a binder are mixed in a weight ratio of 100:10:10. A solvent such as NMP(N-methyl-2-pyrrolidone) is added to the mixture and kneaded to a paste to form a positive electrode collector. The collector is applied to both surfaces of about a 20 μm thick aluminum foil, dried to form a positive electrode plate. A carboxymethylcellulose aqueous solution is applied to the surface of the positive electrode plate, dried, and the positive electrode plate is rolled and cut into a sheet. A separator is placed between the positive electrode plate and a negative electrode plate, and they are spirally wound to obtain a spiral electrode. The thickness of the carboxymethylcellulose thin film is made about 5 μm or less. |
