A review of current rate-dependent phase transformations of lithium metal orthosilicate cathode materials for Li-ion batteries

Abstract

Lithium metal orthosilicates, Li2MSiO4 (M = Fe, Mn, Co, Ni, and their mixtures), have been attracting significant attention as alternative cathodes for next-generation high energy Li-ion batteries (LIBs). The high capacity of these cathodes is attributed to two reversible transitions, those of Li2MSiO4 to LiMSiO4 and LiMSiO4 to MSiO4 phases involving two Li+ ions per mole. However, due to their complex structures and phase transformation behaviors, these materials are not yet available for practical commercial applications. Rate capability is one of the most important properties of cathode materials that are affected by phase transformations. This review will comprehensively summarize the current knowledge of the rate-dependent phase transformations of Li2MSiO4 materials based on various characterization tools to facilitate future developments of these high potential cathode materials for future LIBs.