Silicate cathodes for lithium batteries: alternatives to phosphates?

Abstract

Polyoxyanion compounds, particularly the olivine-phosphate LiFePO₄, are receiving considerable attention as alternative cathodes for rechargeable lithium batteries. More recently, an entirely new class of polyoxyanion cathodes based on the orthosilicates, Li₂MSiO₄ (where M = Mn, Fe, and Co), has been attracting growing interest. In the case of Li₂FeSiO₄, iron and silicon are among the most abundant and lowest cost elements, and hence offer the tantalising prospect of preparing cheap and safe cathodes from rust and sand! This Highlight presents an overview of recent developments and future challenges of silicate cathode materials focusing on their structural polymorphs, electrochemical behaviour and nanomaterials chemistry.