Wrinkled Graphene-Reinforced Nickel Sulfide Thin Film as High-Performance Binder-Free Anode for Sodium-Ion Battery

Sodium-ion batteries (SIBs) recently have received a worldwide attention due to the resource abundance of sodium and similar battery chemistry with lithium-ion batteries (LIBs). However, search for suitable anodes for SIBs still remains a challenge since graphitized carbon, the anode for commercial LIBs, usually exhibits low electrochemical Na-storage activity. In this work, a unique graphene-reinforced Ni₃S₂ thin film (Ni₃S₂/G) has been constructed and investigated as a promising anode for SIBs. The Ni₃S₂ thin film has a thickness of 200–300 nm and is composed of small sized crystals of around 100 nm. The graphene has a wrinkled surface profile which offers three-dimensional networks for electron conductivity and structural reinforcement. The Ni₃S₂/G thin film exhibits high capacity, excellent cycling stability and good rate capability due to the introduction of wrinkled graphene. Ni₃S₂/G can deliver a high initial capacity of 791 mAh g⁻¹ at 50 mA g⁻¹. The capacity can be maintained at 563 mAh g⁻¹ after 110 cycles. This work provides a unique design for high-performance SIBs anodes.