Storage and cycling performance of Cr-modified spinel at elevated temperatures

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. Li_1.02Cr_0.1Mn₂O₄ shows very low rate of capacity rention, 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°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 Li_1+xMn₂O₄. 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.