| 摘要 |
PROBLEM TO BE SOLVED: To enable charging/discharging characteristics of a secondary battery to be improved by forming positive active material particles in a complex body consisting of LiMn2 O4 and Li2 Mn2 O4 and restricting elution of Mn out of Mn oxide of positive active material during charging and crystal structure destruction of spinel type LiMn2 O4 during discharging. SOLUTION: A mixture of molar ratio 95:5 between LiMn2 O4 powder and LiOH powder is subjected to heat treatment at 600 deg.C for 6 hours in vacuum so as to form a complex whose surface is covered by Li2 Mn2 O4 . In this complex powder 90 pts.wt. carbon black of conductive material 5 pts.wt., and 5 pts.wt. of solid component of binding agent of polyvinylidene fluoride dissolved in N-methyl-2-pyrrolidone are mixed together to form positive black mixture. Hereby, the surface of positive active material LiMn2 O4 particles surfaces are covered by Li2 Mn2 O4 particles and during a charging period elution of Mn included in LiMn2 O4 can be restricted. In addition, the crystal structure of LiMn2 O4 particles can be stabilized also against storage/release of Li ions at repetitive charging/discharging, so that cycle characteristic may be improved. |
