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

Rechargeable Mg batteries are promising candidates for highly safe large-scale energy storage batteries owing to the low-cost and non-dendritic metallic Mg anode. However, exploring high-performance cathodes remains a great challenge hindering their development. Herein, a new pseudocapacitive Mg-storage nanowire material (a-MoS3@CNT) is constructed with carbon nanotube (CNT) core and amorphous MoS3 (a-MoS3) outer layer (15 nm thick). The nanowire cathode exhibits a high reversible capacity of 175 mAh g−1 at 100 mA g‒1, a good rate performance of 50 mAh g‒1 at 1000 mA g‒1, and an outstanding long-term cycleability over 500 cycles. Further mechanism investigation demonstrates the Mg-storage of a-MoS3@CNT is mainly achieved by 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 tailing.