Composites of Silicon@Li4Ti5O12 and Graphite for High-Capacity Lithium-Ion Battery Anode Materials

Abstract

Silicon (Si) is a promising anode material for lithium-ion batteries owing to its high theoretical capacity. However, it suffers from poor capacity retention during cycling due to mechanical stresses, pulverization, and an unstable solid electrolyte interface. One practical approach to mitigate the problem is a coating design, where nano-sized silicon is encapsulated within a selected protective layer. In this study, silicon nanoparticles have been coated with a protective layer of Li4Ti5O12 (LTO) ceramic and prepared using a water-based sodium alginate binder. It is found that the Si@LTO composites can be combined with graphite to improve battery performance further. The composite electrodes have been tested in half cells at C/10 and 1C rates. The best Si@LTO and graphite composite has an initial high capacity (∼900 mAh g−1 at C/10 and ∼600 mAh g−1 at 1C) and good capacity retention. It is found that this capacity retention is superior to Si@LTO alone and a binary composite of silicon with graphite. These Si@LTO + graphite composites are a promising way to integrate silicon into the development of stable and high-energy-density lithium-ion batteries.