Abstract

A method capable of transforming LiMnBO glass (such as 0.5LiMnO₂–0.5B₂O₃) by appropriate heating into an electrochemically active cathode material is presented. The pristine lithium manganese borate glass prepared by quenching of the melt in air has almost no electrochemical activity within the potential range from 2.5 to 4.5 V vs. Li/Li⁺. The oxidation of Mn²⁺ to Mn³⁺ and Mn⁴⁺ was found to occur around the glass transition temperature (T_g). Single-phase LiMn₂O₄ can be formed by prolonged heating of the glass powders in air to temperatures around T_g. A composite cathode material in which the electrochemically active substance is dispersed on the surface of a fast-ion-conducting matrix was prepared and found to exhibit a cathodic capacity remarkably higher than that of the pristine glass. Good cycling performance between potentials of 2.5 and 4.5 V vs. Li/Li⁺ has also been observed.