The influences of partial substitution of Mn in LiMn2O4 with Cr3+ and Li+ on their charge/discharge profiles were quite different: Cr3+ affected it only in the high-voltage region, while Li+ showed in the both high and low voltage regions. Either Cr3+ or Li+ doping significantly improved the storage and cycling performance of spinel LiMn2O4 at the elevated temperature, specially both doped spinel. Li1.02Cr0.1Mn2O4 shows very low rate of capacity rention, 0.1% per cycle, and maintained a steady discharge capacity of 114mAh/g, 95% of the initial discharge capacity over 50 cycles at 50°C. The chemical analysis and X-ray diffraction measurement indicate that the capacity losses of LiMn2O4 is mainly due to the dissolution of Mn into electrolyte, further transformation to lithium-rich spinel Li1+x Mn2O4. The improvements in their electrochemical profiles for the Cr3+ and Li+ modified spinel is attributed to that the partial substitution of Mn stabilize its structure, thus minimizing the dissolution of Mn into electrolyte, as well as maintaining its original morphologies.