In situ growth of bimetallic nickel cobalt sulfide (NiCo2S4) nanowire arrays encapsulated by nitrogen-doped carbon on carbon cloth as binder-free and flexible electrode for high-performance aqueous Zn batteries

Recently, aqueous nickel-zinc (Ni-Zn) batteries have abundant application potential due to its large-scale energy storage systems. However, traditional cathode materials still have the disadvantage of having much lower specific capacity than their theoretical capacity and poor cycle performance. The development of bond-free flexible cathode electrodes for high-performance aqueous Zn batteries remains a tremendous challenge. Herein, a simple method was reported to in situ grow NiCo2S4 acicular nanowire arrays encapsulated by nitrogen-doped carbon on carbon cloth (denoted as CC@ NC-NiCo2S4) as binder- free and flexible electrode for high-performance aqueous Zn batteries. When CC@ NC-NiCo2S4 was used as a stand-alone cathode material, the prepared aqueous CC@ NC-NiCo2S4//Zn battery exhibits excellent rate capability (0.58 mAh cm(-2) at 2 mA cm(-2) and 0.46 mAh cm(-2) at 20 mA cm(-2)) and superior cycling performance (80% capacity retention at 4.65 A g(-1) after 1000 cycles, based on the NiCo2S4 active material). More importantly, a quasisolid-state CC@NC-NiCo2S4/Zn cell has also been fabricated and exhibits an outstanding energy density of 238 Wh kg(-)1 at a power density of 1.27 kW kg(-1) and 89% capacitance retention for 500 cycles with 5 mA cm(-2). Those results showed that it is much higher than that of other reported (Ni-Zn) batteries, indicating its excellent potential practical applications for high-performance aqueous Zn batteries.