Hexagonal CuSe decorated with reduced graphene oxide as a stable anode for high-performance sodium-ion batteries

Sodium-ion batteries (SIBs) are regarded as one of the most promising secondary energy storage devices. However, there is still a lack of suitable anode materials with stable high capacity. Among various alternatives, CuSe stands out owing to its excellent electrochemical activity, high specific capacity, and excellent cycling stability. Nevertheless, CuSe encounters considerable volume expansion during charge/discharge processes and exhibits sluggish kinetics in its electrochemical reaction. Herein, hexagonal CuSe modified with reduced graphene oxide (rGO) was successfully prepared by adjusting the hydrothermal reaction time. The resulting CuSe@rGO nanocomposites not only enhance electrical conductivity but also provide a buffering matrix that effectively mitigates volume expansion during cycling. After 400 cycles at 1 A g⁻¹, the CuSe@rGO anode demonstrated stable cycling performance and reversible specific capacity up to 407 mAh g⁻¹. Moreover, the interaction between CuSe and rGO facilitates charge transfer at the interface, accelerates the reaction kinetics, and contributes notably to pseudocapacitance. At a high current density of 5 A g⁻¹, CuSe@rGO exhibits outstanding rate capability with a discharge specific capacity of up to 416 mAh g⁻¹. This study provides valuable insights for discovering high-performance anode materials for SIBs.