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 NiCo 2 S 4 acicular nanowire arrays encapsulated by nitrogen-doped carbon on carbon cloth (denoted as CC@NC-NiCo 2 S 4 ) as binder-free and flexible electrode for high-performance aqueous Zn batteries. When CC@NC-NiCo 2 S 4 was used as a stand-alone cathode material, the prepared aqueous CC@NC-NiCo 2 S 4 //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 NiCo 2 S 4 active material). More importantly, a quasi-solid-state CC@NC-NiCo 2 S 4 /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. Graphical Abstract Novel electrode functionalized with NiCo 2 S 4 nanowire arrays encapsulated by carbon was synthesized and exhibits excellent performance for aqueous Zn batteries.