IMPROVEMENT IN THE CYCLING PERFORMANCE OF LIMN2O4 BY THE SUBSTITUTIONOF FE FOR MN

We tried to improve the cycling performance of LiMn2O4 by substituting Fe for Mn. LiFe0.25Mn1.75O4 is the optimum composition which has a re latively large discharge capacity and the largest discharge capacity a t n = 30, and the smallest percentage of capacity deterioration at n = 30, especially with (C-1 - C-30) X 100/C-1 = 5.6%. The variation of d ischarge capacities for the LiFeyMn2-yO4 (y = 0.0, 0.1, 0.25, 0.38, an d 0.5) with cycling can be well expressed by the following equation: C -n/C-o = e(-ktn) where C-n is the discharge capacity at nth cycle, C-0 the theoretical capacity, t=t(1) + t(2) + ... +t(n) (t(n) = dischargi ng time at nth cycle), and k and n constants. (C) 1998 Published by El sevier Science B.V. All rights reserved.