3D layered structure Ti3C2Tx MXene/Ni(OH)2/C with strong catalytic and adsorption capabilities of polysulfides for high-capacity Sodium–Sulfur battery

The room temperature sodium-sulfur battery has attracted researchers' attention due to its ultra-high energy storage capacity and extremely low cost, but its poor cycling performance and severe dissolution of sodium polysulfide hinder its practical application. Here, we report a stable MXene derived composite sulfur host material based on nickel hydroxide coated with carbon nano network, to achieve the adsorption and conversion of sodium polysulfides. Due to the physical constraints provided by the closed layered structure and the synergistic effect of MXene adsorption and Ni(OH)2catalytic activity, the shuttling effect is effectively suppressed. The ex-situ analysis of electrode after reaction shows that the composite material has strong adsorption on polysulfides. In addition, Ni(OH)2can also accelerate the reaction process from sulfur to sodium sulfide. Therefore, Ti3C2Tx/Ni(OH)2/C/S composite cathode can provide extraordinary reversible capacity 1175.3 mAh/g at 0.22C after 100 cycles and excellent long cycle stability (673.5 mAh/g at 2.2 C with a low decay rate of only 0.032% per cycle over 800 cycles).