| 摘要 |
PROBLEM TO BE SOLVED: To enhance the utilization factor of a positive electrode active material and charge/discharge cycle characteristics of a battery by including a carbon base additive and a tin base additive in the positive electrode active material. SOLUTION: A carbon base additive raising porsity for increasing the utilization factor of an active material and a tin base additive for forming a conductive network for preventing short life caused by drop in conductivity are added by 0.05-5 molar percent each to a positive electrode active material, and the ratio of both additives is preferably set to 1-5:5-1. Two functions are developed at the same time, and drop in energy density per electrode plate and peeling off of the active material are prevented. As the carbon base additive, various kinds of graphite or carbon black is used, and as the tin base additive, metallic tin, or a tin compound, or especially a tin oxide having high conductivity, doped with tetra-valent or hexa-valent element is used, and fibrous material having large aspect ratio is preferable from the standpoint of reduction of adding amount and high conductivity. These additives and lead powder mainly comprising lead monoxide, are kneaded together with water and dilute sulfuric acid to prepare lead mix paste.
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