Micro-nano Cu2Se as a stable and ultralong cycle life anode material for sodium-ion batteries

Transition metal selenides have received great attention as promising anode materials for sodium-ion batteries (SIBs). However, it still faces the change of volume and structure, which reduces the rate performance and cycle stability in cycle process. The design of micro-nano hierarchical structure is an important method to improve the structural stability and reaction kinetics in discharge-charge process. In this study, the micro-nano Cu2Se is synthesized using a simple solvothermal and annealing treatment method, and it shows excellent electrochemical performance as anode material for SIBs. It exhibits excellent rate capacity (373.8 mAh g(-1) at 0.1 A g(-1 )and 303.48 mAh g(-1 )when the current density is increased to 10 A g(-1)) and cycling stability (250.3 mAh g(-1 )after 4000 cycles at 5 A g(-1), achieving 85.80% for retention rate). In addition, the deep reaction mechanism of Cu2Se has been explored through ex situ XRD and HRTEM. (C) 2022 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.