METHOD FOR REGULATING TERMINAL VOLTAGE OF CATHODE DURING OVERDISCHARGE AND CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY

摘要

Provided are a method for regulating the terminal voltage of a positive electrode when the potential difference of a positive electrode and a negative electrode in case of overcharge is 0 V, a positive electrode active material for a lithium secondary battery, and a lithium secondary battery using the positive electrode active material whose capacity does not reduce largely even after overcharge and which is excellent in capacity recovery after overcharge. The method comprises the step of adding an additive of a lithium transition metal oxide whose irreversible capacity during initial charge/discharge is larger than that of a positive electrode active material containing a lithium transition metal oxide absorbing and desorbing a lithium ion, to the positive electrode active material containing a lithium transition metal oxide absorbing and desorbing a lithium ion, to prepare a positive electrode. Preferably the additive is a lithium nickel oxide represented by Li_(2+x) Li_(1-y) M_y O_(2+a) or a lithium nickel oxide whose surface is coated with an oxide other than the lithium nickel oxide, wherein 0.5<=x<=0.5; 0<=y<1; o<=a<0.3; and M is at least one element selected from the group consisting of P, B, C, Al, Sc, Sr, Ti, V, Zr, Mn, Fe, Co, Cu, Zn, Cr, Mg, Nb, Mo and Cd.