Effects of metal source in metal substitution of lithium manganese oxide spinel

Usefulness of W substitution for improvement of battery performance of LiMn₂O₄ cathode was investigated. Small amounts of tungsten were incorporated into LiMn₂O₄ spinel instead of available Mn. For this purpose, two sources of tungsten (metallic W or WO₃) were examined. W concentration and source have significant influence on both morphology and electrochemical behavior of W-substituted LiMn₂O₄ spinels. W substitution of LiMn₂O₄ spinel can lead to the formation of uniform spinel particles and improved battery performance. Cyclic voltammetric behaviors of the samples were examined in an aqueous solution, and Li diffusion process was investigated for different cases. The best case was the LiW_0.01Mn_1.99O₄ spinel prepared from metallic W powder, as exhibits excellent rate capability, but better cycleability was observed for the LiW_0.01Mn_1.99O₄ spinel prepared from WO₃. This means that because of significant influence of the dopant source, this parameter should be chosen in respect with the desire improvement.