| 摘要 |
PURPOSE:To prevent a negative electrode carbon material from deteriorating by oxidation reaction due to overdischarge by forming a nonaqueous electrolyte secondary battery with a lithium compound oxide used for positive electrode active material and a carbon material for the negative electrode. CONSTITUTION:A positive electrode active material is formed of a material LiyNi1-xMnxO2, which has a stable region even at an open circuit voltage of 3V or less and is excellent in electrochemical reversibility to match a charge- discharge reaction, with its potential determinant factor depending on the amount of Li in the active material. The potential is therefore determined by (y) value, and when 1.0<(y)<1.6, in which case a large amount of Li for battery formation is retained, the positive electrode active material has a low potential region of 3V or less, and in a charged state with 0.4<Y<1.0 in which case Li is deintercalated, the active material has a high potential region of greater than 3V. Therefore, the electrochemical reversibility is maintained even in a normal charge-discharge reaction, and even if the positive and negative electrodes become equipotential due to overdischarge, the negative electrode can be prevented from deteriorating by oxidation reaction. |
