Synergistically enhancing cycleability and rate performance of sodium titanate nanowire anode via hydrogenation and carbon coating for advanced sodium ion batteries

Layered alkali-metal titanate materials are considered as attractive anodes for sodium ion batteries due to their favorable safety and low cost. However, their practical implementation faces major challenges of low electronic conductivity and inevitable volume variation during Na + intercalation and de-intercalation, which are generally difficult to conquer by a single modification method. Herein, a synergistically enhancing strategy to promote the electrochemical performance of Na 2 Ti 2 O 5 nanowire array anode via simultaneous hydrogenation and carbon coating is developed. Hydrogenation leads to partially reduced titanium; together with conductive carbon layer, it endows Na 2 Ti 2 O 5 with fast electron transport and structural stability. The resulting H−Na 2 Ti 2 O 5 @C anode exhibits enhanced rate capability (8.0C, 165 mAh·g −1 ) and stable cycle performance up to 1000 times in sodium-ion half-cells (the capacity of H−Na 2 Ti 2 O 5 without carbon fades drastically after only 100 cycles). In addition, a new-coupling full cell is further designed with graphene hybridized high-voltage Na 3 (VO 0.5 ) 2 (PO 4 ) 2 F 2 as cathode, capable of delivering a high specific energy density of 212.1 Wh·kg −1 (based on the mass of both anode and cathode) and good rate and cycling stability. This work may offer inspiration for synergistic optimization of electrode materials for advanced electrochemical energy storage devices. Graphical abstract