Self-Assembly TiNb2O7@MXene Anode Material for Fast and Stable Lithium Storage

Abstract

TiNb2O7 (TNO) is a high-specific-capacity intercalation-type anodic material with excellent cycle performance and appropriate working potential (∼1.6 V vs Li+/Li). However, its low electronic conductivity and lithium-ion diffusion coefficient can lead to poor kinetics, which has become a bottleneck that needs to be urgently addressed for the further development of TiNb2O7. Herein, a unique MXene encapsulating TNO particles (TNO@MXene) was fabricated through a simple electrostatic self-assembly process. The MXene nanosheets act as the underlying conductive substrate, which can not only enable reversible fast electron and ion transport at the interface and enhance the electrochemical activity of TNO but also prevent TNO particles from aggregating during lithiation/delithiation. Consequently, the TNO@MXene composite exhibits significantly improved lithium storage characteristics compared with those of pristine TNO, such as high reversible capacity (346.4 mA h g–1 at 0.1C), excellent cycling stability (92.3% capacity retention after 500 cycles at 10C), and exceptional superior rate capability (166 mA h g–1 at 20C). These findings proved the efficacy of the MXene substrate in enhancing the lithium-ion storage capabilities of TNO and may encourage the fabrication of high-power lithium-ion batteries.