A Sandwich‐Structured Na 2 Ti 6 O 13 /Reduced Graphene Oxide Composite for Improved Energy Storage in Sodium‐Ion Batteries

Abstract 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. Na 2 Ti 6 O 13 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, Na 2 Ti 6 O 13 has intrinsic limitations such as electrical conductivity. To overcome these obstacles, a sandwich‐structured Na 2 Ti 6 O 13 /reduced graphene oxide (rGO) composite is synthesized through a liquid‐phase exfoliation and restacking method using electrostatic interactions. The Na 2 Ti 6 O 13 /rGO composite showed remarkable improvement in both reversible discharge capacity and cycle stability. In comparison to bare Na 2 Ti 6 O 13 with a discharge capacity of 20.1 mAh g −1 after 500 cycles, the Na 2 Ti 6 O 13 /rGO1 composite displayed a discharge capacity of 196.5 mAh g −1 at a current density of 0.1 A g −1 and a voltage range of 0.01–2.5 V. Furthermore, the Na 2 Ti 6 O 13 /rGO1||Na 3 V 2 (PO 4 ) 3 full cell are assembled, discharging an energy density of 251.3 Wh kg −1 anode with a power density of 228.1 W kg −1 anode after 100 cycles in a voltage range of 1.0–4.0 V.