Using amorphous CoSx hollow nanocages as cathodes for high-performance magnesium-lithium dual-ion batteries

Magnesium-lithium dual-ion batteries (MLDBs) use Mg 2+ /Li + dual-ion electrolytes and safe magnesium anodes to achieve high performance. 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 cobalt sulfide nanocages with different etching time (AH-CoS x -T, T = 30, 60 and 120 min) as cathode materials for high performance MLDBs. The results indicate that AH-CoS x -60 cathodes show a high initial capacity of 618 mAh g −1 at 0.1 A g −1 and maintain 130 mAh g −1 at 0.5 A g −1 after 500 cycles, indicative of that the recorded high-performance benefits from amorphous and mesoporous structure. Moreover, ex-situ SEM and XPS analyses confirm that Mg 2+ /Li + co-reactions occur in AH-CoS x -60 cathodes during discharge/charge. For comparison, we also sintered AH-CoS x -60 to generate crystalline Co 9 S 8 and Co 1– x S, respectively. Results show that both Co 9 S 8 and Co 1- x S cathodes for MLDBs exhibit poorer cycle stability and much longer activation process, providing further evidence of the advantageous amorphous structure of AH-CoS x -60. Our work thus provides an insight into preparing amorphous conversion-type cathodes with high capacities and short activation process for high performance MLDBs.