Using Amorphous Cosx Hollow Nanocages as Cathodes for High-Performance Magnesium-Lithium Dual-Ion Batteries

Magnesium-lithium dual-ion batteries (MLDBs) use Mg2+ /Li+ dual-ion electrolytes and safe magnesium anodes to achieve high performances. Coincidentally, conversion-type chalcogenides are widely used as cathodes for MLDBs due to their high theoretical specific capacities. In this work, we prepared amorphous hollow CoSx nanocage cathode materials for high-performance MLDBs. The results display CoSx obtained by 60 min of etching (AH-CoSx-60) as cathodes with a high initial capacity (620 mAh g–1 at 0.1 A g–1), that retains a capacity of 130 mAh g–1 at 0.5 A g–1 after 500 cycles with a good rate capability (190 mAh g–1 at 0.5 A g–1). Moreover, using ex-situ SEM and XPS analyses, Mg2+/Li+ co-reactions seem to occur at the CoSx cathodes during discharge/charge, indicating that the recorded high-performance benefits from amorphous and mesoporous structure of CoSx. For comparison, we also sintered AH-CoSx-60 to generate crystalline Co9S8 and Co1–xS, respectively. Results show that both Co9S8 and Co1-xS exhibit poorer cycle stability and much longer activation process, providing further evidence of the advantages of the AH-CoSx-60 amorphous structures for cathodes. Our work thus provides an insight into making high-performance conversion-type cathodes with high capacity and short activation process for MLDBs.