| Summary: | LiMn2O4 is an attractive 4 V positive material in lithium rechargeable batteries owing to its favourable electrochemical characteristics besides its economic and environmental advantages. However, problems of limited cyclability, especially at elevated temperatures, have limited the utility and commercialization of this cathode material. Stabilization of the LiMn2O4 spinel structure has been sought to be realized by doping the spinel with suitable cations. In this paper, the results of an exploratory research on the capacity and cyclability of LiMn2O4 cathodes simultaneously doped with Cr3+ and Mg2+ are reported. LiMg y1Cr y2Mn2-y1-y2O4 spinels with y1 = 0.00, 0.05, 0.10, 0.20, 0.25 and 0.30 and y2 (0.3 - y1) were synthesized by a solid-state fusion method. While Mg2+ bestows a positive effect on cyclability, it leads to a considerable reduction in capacity due to the oxidation of Mn3+ to the inactive Mn4+ as a result of charge compensation. Cr3+ on the other hand, leads only to half as much reduction in capacity while according added stability to the structure. Any expectation of a synergistic effect by Cr3+ and Mg2+ ions was belied by these findings.
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