Double-shelled Mn-doped NiCo2S4 hollow nanowire arrays for high-reactivity hybrid supercapacitors

Double-shelled Mn-doped NiCo2S4 (NiCoMn-S-h) hollow nanowire arrays are synthesized for optimized reactivity of hybrid supercapacitors. The NiCoMn-S-h is converted based on anion exchange reaction, which maintains the overall array structure of precursor and forms a double-shelled hollow structure. It is found that Mn composition lowers outer diffusion rate of precursor for the formation of inner shell of double-shelled structure. The specific structure and Mn-doping promote the performance of sulfides. As a result, the NiCoMn-S-h shows high specific capacity, improved rate performance and low charge transfer resistance as the battery electrode for hybrid supercapacitors. The NiCoMn-S-h exhibits a specific capacity of 948 C g-1 at 1 A g-1 combined with a highly retained specific capacity of 614 C g- 1 at 50 A g-1. The NiCoMn-S-h displays well matched performance with the capacitive electrode in hybrid supercapacitors, which exhibits both high-energy and high-power performances with specific energy of 44.9 Wh kg-1 at 780 W kg-1 and 19.2 Wh kg-1 at 23.4 kW kg-1 delivered.