Synchronous Manipulation of Ion and Electron Transfer in Wadsley-Roth Phase Ti-Nb Oxides for Fast-Charging Lithium-Ion Batteries.

Implementing fast-charging lithium-ion batteries (LIBs) is severely hindered by the issues of Li plating and poor rate capability for conventional graphite anode. Wadsley-Roth phase TiNb 2 O 7 is regarded as a promising anode candidate to satisfy the requirements of fast-charging LIBs. However, the unsatisfactory electrochemical kinetics resulting from sluggish ion and electron transfer still limit its wide applications. Herein, an effective strategy is proposed to synchronously improve the ion and electron transfer of TiNb 2 O 7 by incorporation of oxygen vacancy and N-doped graphene matrix (TNO - x @N-G), which is designed by combination of solution-combustion and electrostatic self-assembly approach. Theoretical calculations demonstrate that Li + intercalation gives rise to the semi-metallic characteristics of lithiated phases (Li y TNO - x ), leading to the self-accelerated electron transport. Moreover, in situ X-ray diffraction and Raman measurements reveal the highly reversible structural evolution of the TNO - x @N-G during cycling. Consequently, the TNO - x @N-G delivers a higher reversible capacity of 199.0 mAh g -1 and a higher capacity retention of 86.5% than those of pristine TNO (155.8 mAh g -1 , 59.4%) at 10 C after 2000 cycles. Importantly, various electrochemical devices including lithium-ion full battery and hybrid lithium-ion capacitor by using the TNO - x @N-G anode exhibit excellent rate capability and cycling stability, verifying its potential in practical applications.