One‐Step Synthesis of Highly Oxygen‐Deficient Lithium Titanate Oxide with Conformal Amorphous Carbon Coating as Anode Material for Lithium Ion Batteries

Abstract

The lithium titanate defect spinel, Li4Ti5O12 (LTO), is a promising “zero‐strain” anode material for lithium‐ion batteries in cycling‐demanding applications. However, the low‐rate capability limits its range of applications. Surface modifications, for example, coating and defect engineering, play an intriguing role in interfacial electrochemical processes. Herein, a novel synthesis of highly oxygen‐deficient “defective‐LTO” anode material with high‐rate performance is reported. It is synthesized using conventional precursors via a one‐pot thermal reduction process. A high level of oxygen vacancies of ≈6.5 at% and conformal amorphous carbon coating are achieved simultaneously, resulting in a compounding effect for a high discharge capacity of 123 mAh g−1 with Coulombic efficiency of 99.8% at 10 C‐rate. Ab initio calculations foresight that oxygen vacancies increase the electron donor density of the neighboring titanium atoms, while conformal amorphous carbon significantly lowers interfacial charge‐transfer resistance. The formation mechanism, as well as the origin of enhanced electrochemical properties, is elaborated in this paper.