A Sandwich-Structured NaTiO/Reduced Graphene Oxide Composite for Improved Energy Storage in Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have the potential to be a cost-effective and sustainable solution for large-scale energy storage systems (ESSs) due to the abundance of sodium reserves. NaTiO has been considered as a suitable candidate for use as an anode material in SIBs owing to its environmental friendliness, low cost, and excellent cycling stability. Despite its advantages, NaTiO has intrinsic limitations such as electrical conductivity. To overcome these obstacles, a sandwich-structured NaTiO/reduced graphene oxide (rGO) composite is synthesized through a liquid-phase exfoliation and restacking method using electrostatic interactions. The NaTiO/rGO composite showed remarkable improvement in both reversible discharge capacity and cycle stability. In comparison to bare NaTiO with a discharge capacity of 20.1 mAh g after 500 cycles, the NaTiO/rGO1 composite displayed a discharge capacity of 196.5 mAh g at a current density of 0.1 A g and a voltage range of 0.01-2.5 V. Furthermore, the NaTiO/rGO1||NaV(PO) full cell are assembled, discharging an energy density of 251.3 Wh kg with a power density of 228.1 W kg after 100 cycles in a voltage range of 1.0-4.0 V.