The tellurium-induced CoSe polyhedral porous nano-structured materials as high-performance cathodes for rechargeable magnesium batteries

Rechargeable magnesium batteries (RMBs) are cost-effective and dendrite-free, making them desirable for large-scale applications. Nevertheless, the exploration of high-performance cathodes still remains a great challenge in magnesium battery research. Herein, the CoSe porous polyhedra induced by Te heteroatoms (CoSe/Te) are successfully prepared by two-step metal-organic framework (MOF)-template assisted method and investigated as high-efficiency cathodes for rechargeable MIBs. In this regard, the affluent porous structure can facilitate the transport of Mg2+ ions while the introduction of Te heteroatoms can reduce the conversion reaction barrier, boost the kinetics and redox reversibility and excite the electron conduction to build active nanostructured domains for highly reversible Mg storage reactions. As a consequence, the CoSe/Te maintains the high specific capacity of 150.6 mAh g−1 after 600 cycles at 200 mA g−1, with a superior capacity retention rate of 75.3%. Moreover, the specific capacity of such electrode materials changed from 260 mAh g−1 to 41 mAh g−1 when the current density increased from 100 mA g−1 to 2000 mA g−1, and gradually recovered to 256.5 mAh g−1 when the current density returned to 100 mAh g−1, exhibiting a better rate performance. This work highlights how micro-nanostructures can favor magnesium storage reaction reversibility and cyclability and also provide insights into rational electrode design for storing magnesium cations in future studies.