POSITIVE ELECTRODE MATERIAL FOR LITHIUM SECONDARY CELL, POSITIVE ELECTRODE FOR LITHIUM SECONDARY CELL AND LITHIUM SECONDARY CELL

摘要

A positive electrode material for a lithium secondary cell containing a manganese oxide and/or a lithium manganese composite oxide as a positive electrode active material and exhibiting a decomposed amount of PF6 anion as measured by the following storage test of 10 mu mol or less, the storage test having the procedure that: a) a cell element is assembled which uses a positive electrode having a collector and, crimped thereto, 24 mg of a positive electrode material, a counter electrode comprising Li, and a mixed solution from EC and DMC containing 1.0 mol/l of LiPF6 as an electrolyte, and the cell element is charged with a charge current density of 0.2 mA/cm<2> until a high limit of 4.2 V and then destructed; the positive electrode is taken out and immersed b) under an argon gas atmosphere, c) in a dried PTFE container, d) into a mixed solution from EC and DEC containing 1.0 mol/l of LiPF6, and is e) stored for a week at 80 DEG C; and a decomposed amount of PF6 anion is determined through measuring the amounts of PF6 anion in the mixed solution before and after the storage.