Cation regulation-induced enhancement of dual conductivity facilitating high-stability sodium storage

Abstract

Transition-metal sulfides (TMSs) have been demonstrated to be heartening anodes for sodium-ion batteries because of their alterable nanostructures, large theoretical capacity and environmental friendliness. Nevertheless, the insufficient electronic and ionic conductivities of TMSs result in inferior rate performance and cycling durability, which poses a major obstacle to their rapid commercialization. Herein, we propose a cation regulation strategy to modulate the electronic structure of CuS. DFT calculations combined with kinetics analyses demonstrate that cationic substitution optimizes the electronic structure of Cu_1-xW_xS, thus endowing with superior charge transfer kinetics and low ion diffusion barrier. As anticipated, Cu_1-xW_xS exhibits a remarkable reversible capacity (369.0 mAh g⁻¹ at 0.3 A g⁻¹ after 500 cycles), excellent rate capability and high-rate cycling stability (324.2 mA h g⁻¹ at a high current density of 5.0 A g⁻¹ after 1400 cycles). Besides, a stepwise reaction process is revealed by ex-situ investigations. This work presents a promising heteroatom-engineering approach to enhance electrode structures for next-generation energy storage applications.