Twin boundary CdxZn1−xS: a new anode for high reversibility and stability lithium/sodium-ion batteries

Abstract

Defect engineering is considered an effective strategy to improve the electrochemical performance of batteries because of its ability to promote ion diffusion and increase reactive sites in electrode materials. Twin boundaries as interfacial defects offer new opportunities for ion transport in nanomaterials. In this work, Cd_xZn_1−xS with twin boundaries (Cd_xZn_1−xS-B) was designed and fabricated based on the theories of crystal structure analysis and density functional theory (DFT) calculations. We demonstrate that the introduction of Zn into CdS to form Cd_xZn_1−xS-B enables fast lithium-ion diffusion and enhances structural stability. Its reversible specific capacity is approximately four times that of its corresponding single metal sulfide electrode and the cycle stability is significantly better than that of Cd_xZn_1−xS without twin boundaries. Notably, Cd_0.7Zn_0.3S-B delivers a high specific capacity of 404.8 mA h g⁻¹ at 2.0 A g⁻¹ after 1900 cycles, and the Cd_0.7Zn_0.3S-B||LiFePO₄ full cell maintained a capacity retention of 84.3% after 150 cycles at 500 mA g⁻¹. Cd_0.7Zn_0.3S-B also shows excellent sodium storage performance. This study demonstrates that designing electrode materials via introducing twin boundaries can promote the development of next generation rechargeable batteries.