Synthesis of Lithium Manganese Spinel Oxide Li4Mn5O12.

Abstract

Li4Mn5O12 particles were prepared by calcination of Li-hydroxide monohydrate and γ-Mn2O3, which was synthesized by the thermal decomposition of Mn-oxalate, at temperature from 400 to 750°C in static air or oxygen atmosphere. The lattice constant varied with the preparation conditions: in the same atmosphere, the lattice constant increased with the calcination temperature, and in the fixed preparation temperature, the calcination in oxygen atmosphere brought smaller lattice constant than that in static air. Additionally, the specimen prepared at lower calcination temperature exhibited higher electrochemical capacity in 3 V region with better cycle performance. These variations are related to the average Mn valence state, and higher valence state of Mn is required for high perfromance of Li4Mn5O12 as 3 V cathode material. The low-temperature synthesis is thought to be suitable for them.