Storage and cycling performance of Cr-modified spinel at elevated

The influences of partial substitution of Mn in LiMn2O4 with Cr3+ and Li+ o n their charge/discharge profiles were quite different: Cr3+ affected it on ly in the high-voltage region, while Li+ showed in the both high and low vo ltage regions. Either Cr3+ or Li doping significantly improved the storage and cycling performance of spinel LiMn2O4 at the elevated temperature, spec ially both doped spinel. Li1.02Cr0.1Mn2O4 shows very low rate of capacity r ention, 0.1 % per cycle, and maintained a steady discharge capacity of 114 mAh/g, 95% of the initial discharge capacity over 50 cycles at 50 degreesC. The chemical analysis and X-ray diffraction measurement indicate that the capacity losses of LiMn2O4 is mainly due to the dissolution of Mn into elec trolyte, further transformation to lithium-rich spinet Li1+xMn2O4. The impr ovements in their electrochemical profiles for the Cr and Li modified spine l is attributed to that the partial substitution of Mn stabilize its struct ure, thus minimizing the dissolution of Mn into electrolyte, as well as mai ntaining its original morphologies. (C) 2001 Elsevier Science B.V. All righ ts reserved.