| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress the degradation of battery characteristics in a nonaqueous electrolyte secondary battery with the charging voltage set to 4.25 V or higher. <P>SOLUTION: A positive electrode active material contains a lithium transition metal composite oxide expressed by an expression: Li<SB>c</SB>Co<SB>(1-d-g)</SB>Al<SB>g</SB>M'<SB>d</SB>O<SB>(2-e)</SB>F<SB>f</SB>(wherein c, d, e, f, g are values within the ranges of 0.9≤c≤1.2, 0≤d≤0.5, -0.1≤e≤0.2, 0≤f≤0.1, 0.015≤g≤0.045, and M' represents at least one kind of element selected out of Ni, Mn, Mg, B, Ti, V, Cr, Fe, Cu, Zn, Mo, Sn, Ca, Sr, W, M). It is preferable to use the lithium transition metal composite oxide mixed with a lithium transition metal composite oxide expressed by an expression: Li<SB>h</SB>Co<SB>(1-i)</SB>M"<SB>i</SB>O<SB>(2-j)</SB>F<SB>k</SB>(wherein h, i, j, k are values within the ranges of 0.9≤h≤1.2, 0≤i≤0.5, -0.1≤j≤0.2, 0≤k≤0.1). <P>COPYRIGHT: (C)2008,JPO&INPIT |
