Patent number: 8178238
Abstract: A positive-electrode active material for a lithium-ion secondary battery has an average composition expressed by the following formula (1): LixCo1-y-zMyCezOb-aXa ??(1) wherein M represents at least one element selected from the group consisting of boron B, magnesium Mg, aluminum Al, silicon Si, phosphorous P, sulfur S, titanium Ti, chromium Cr, manganese Mn, iron Fe, cobalt Co, nickel Ni, copper Cu, zinc Zn, gallium Ga, yttrium Y, zirconium Zr, molybdenum Mo, silver Ag, tungsten W, indium In, tin Sn, lead Pb, and antimony Sb, X represents a halogen element, and x, y, z, a, and b satisfy 0.2<x?1.2, 0?y?0.1, 0.5<z?5.0, 1.8?b?2.2, and 0?a?1.0, respectively, and the concentration of cerium Ce is higher in the vicinity of the surface than in the inside.
Type:
Grant
Filed:
November 12, 2008
Date of Patent:
May 15, 2012
Assignee:
Sony Corporation
Inventors:
Masanori Soma, Masayuki Ihara, Kenichi Kawase, Atsumichi Kawashima