Synthesis of Manganese Dioxide by Sol-Gel Method for Lithium Primary Cells

Abstract

Sodium manganese composite oxides were prepared by the so1-gel method using manganese acetate, sodium acetate and tartaric acid. Manganese dioxides were obtained by extraction of sodium ion from the composite oxides in nitric acid solution. It was confirmed from XRD patterns that γ-MnO₂ phase was formed in low molar ratio (Na/Mn ≦ 0.3) of sodium acetate to manganese acetate in starting materials, and the formation of α-MnO₂ phase was observed in a higher ratio. The specific surface areas were 230-240 m² g⁻¹. The discharge capacities of the products heated at 375°C as a cathode material in lithium/manganese oxide battery were 250-260 mAh g⁻¹ regardless of Na/Mn ratio. The capacities were higher than that of the electrolytic manganese dioxide (207 mAh·g⁻¹). It was found that the composite oxide prepared using the sol-gel method is hopeful as a cathode material for lithium/manganese dioxide battery.