Highly oxidized state dopant induced Nb-O bond distortion of TiNb2O7 for extremely fast-charging batteries

TiNb2O7 (TNO) has emerged as a highly potential power-type anodes for extremely fast-charging batteries. Nevertheless, the inherent electron conductivity and crystalline stability of TNO, limiting its actual capacity. Herein, a TNO anode doped by highly oxidized state ions is designed for regulating unit cell volume expansion, oxygen vacancies generation and charge mobility through induced Nb-O bond distortion. The Ce0.01-TNO electrode shows a high discharge capacity of 181 mAh·g-1 at 20 C after 1000 cycles. Meanwhile, the density functional theory simulations demonstrate that decreased ion-diffusion barrier and increased electronic conductivity are obtained by narrowing the bandgap and introducing impurity bands induced by Ce doping. This work provides an effective strategy to enhance the electrochemical performance of TiNb2O7, making a guideline to construct fast-charging batteries with a prolonged cycle lifespan.