A novel nickel cobalt sulfide-indium (hydroxy) sulfide [NiCo2S4@In(OH)xSy] composites for LAGP-based all-solid-state lithium-ion capacitors

Abstract

Metal sulfides have attracted the attention of researchers as electrode materials in energy storage systems because of their superior electrochemical performance. In this study, we synthesized a nickel cobalt sulfide@indium(hydroxy) sulfide nanoarchitecture (NiCo2S4@In(OH)xSy) using a one-step hydrothermal method and investigated its potential as a high-performance anode material for lithium-ion capacitors (LICs). The volume expansion of sulfides during charge-storage can be reduced by fabricating suitable ternary sulfide composites. This unique composite highlights the importance of –OH bonding for better charge kinetics. The NiCo2S4@In(OH)xSy composite nanoarchitecture as an anode can achieve a high specific capacity of 1277 mA h g−1 at 0.1 A/g, high rate capability, and long cycling performance. Furthermore, the all-solid-state LIC device fabricated using NiCo2S4@In(OH)xSy as anode, activated carbon as cathode, and LAGP (Li1.5Al0.5Ge1.5P3O12)-based solid-state electrolyte/separator can deliver a high energy density of 172.4 Wh kg−1 at 423.5 W kg−1 and 70.6 Wh kg−1 even at a high power density of 8470 W kg−1.