THE SPINEL PHASES LIM(Y)MN(2-Y)O(4) (M=CO,CR,NI) AS THE CATHODE FOR RECHARGEABLE LITHIUM BATTERIES

To improve the cycle performance of spinel LiMn2O4 as the cathode of 4 V class Lithium secondary batteries, the quaternary spinel phases LiM (y)Mn(2-y) O-4 (M = Co, Cr, Ni; y = 1/12, 1/9, 1/6, 1/3) were prepared at 750 degrees C in air. X-ray diffraction and electrochemical studie s were carried out using the Li\Li(x)M(y)Mn(2-y)O(4) cells. These cath odes were more tolerant to repeated lithium extraction and insertion t han a standard LiMn2O4 spinel electrode in spite of a small reduction in the initial capacity. Considering both cycle life and capacity dens ity, LiCo1/6Mn11/O-6(4) showed good cycle performance with an energy d ensity of 370 Wh kg(-1) at the 300th cycle. The improvement in cycling performance is attributed to the stabilization in the spinel structur e by the doped metal cations.