Enhanced Cycle Stability of Na2Ti3O7 Nanosheets Grown in Situ on Nickel Foam as an Anode for Sodium-Ion Batteries

In this work, a Na2Ti3O7 nanosheets@nickel foam material prepared through a hydrothermal synthesis method is applied as an electrode material for sodium batteries without any conductive carbon black or binder. Nickel foam promotes the uniform dispersion of the Na2Ti3O7 nanosheets and contributes to improve the conductivity. In particular, the Na2Ti3O7 nanosheets@nickel foam structure not only provides an electronic transport channel but also increases the structural stability of the material during charge and discharge and further promotes the reaction kinetics of the electrode during charging and discharging. The initial capacity of the Na2Ti3O7 nanosheets@nickel foam reaches approximately 300.2 mAh g(-1) at a current density of 20 mA g(-1). The capacity reaches 96.4, 67.2, and 50.1 mAh g(-1) at current densities of 100, 200, and 400 mA g(-1), respectively. The capacity can reach 140 mAh g(-1) at 50 mA g(-1) and still reaches 81.7 mAh g(-1) after 500 cycles. The results show that the Na2Ti3O7 nanosheets@nickel foam structure can effectively overcome the disadvantage of the poor ion/electron conductivity of Na2Ti3O7 when used as an electrode material for sodium batteries. Therefore, Na2Ti3O7 nanosheets@nickel foam without a binder or conductive additive is a promising anode material for sodium-ion batteries.