Plasma-Induced Defect Engineering in TiNb2O7 for Boosting Lithium-Ion Diffusion

The development of a high-performance anode is critical for the design of ultrahigh-capacity lithium-ion batteries to participate in next-generation energy-storage devices. However, the delocalization transition and sluggish reaction kinetics during TiNb2O7 (TNO) relithiation lead to its low rate performance and rapid capacity decay. In this work, the ball-milling method and plasma technology are used to construct TNO nanocomposites in which defect-rich TNO particles are tightly encapsulated by an amorphous layer. Through structural characterization, electrochemical behavior tests, and kinetic calculations, the increase of oxygen vacancies and other defects can optimize the electronic structure and achieve rapid electron transport and ion migration, and the dense amorphous layer can inhibit the internal stress and volume expansion of the electrode during cycling. As a result, the optimized PTNO anode has excellent lithium storage capacity with a high capacity of 347.9 mA·h·g–1 at 0.1C, a high rate performance of 57.5 mA·h·g–1 at 30C, and an excellent stability of 1000 cycles at 10C. This study provides a new perspective on the design of interface engineering to achieve highly reversible and durable secondary battery anodes.