a-MoS3@CNT nanowire cathode for rechargeable Mg batteries: a pseudocapacitive approach for efficient Mg-storage

Abstract

Rechargeable Mg batteries are promising candidates for highly safe large-scale energy storage batteries owing to their low-cost and non-dendritic metallic Mg anode. However, exploration of high-performance cathodes remains a great challenge hindering their development. Herein, a new pseudocapacitive Mg-storage nanowire material (a-MoS₃@CNT) is constructed with a carbon nanotube (CNT) core and an amorphous MoS₃ (a-MoS₃) outer layer (15 nm thick). The nanowire cathode exhibits a high reversible capacity of 175 mA h g⁻¹ at 100 mA g⁻¹, a good rate performance of 50 mA h g⁻¹ at 1000 mA g⁻¹, and an outstanding long-term cyclability over 500 cycles. Further investigation of the mechanism demonstrates that the Mg-storage of a-MoS₃@CNT is mainly achieved by the pseudocapacitance of a-MoS₃, in which Mg²⁺ ions show fast solid-state diffusion kinetics. The present results demonstrate a new approach for efficient Mg-storage using pseudocapacitive materials, and the performance and solid-state Mg²⁺ diffusion kinetics could be optimized by delicate morphology tailoring.