Construction of Zn–Co–Ni–Se nanosheet arrays on nickel foam for hybrid supercapacitors

Abstract The polymetallic selenides exhibit rich redox reactions and high conductivity, making them promising electroactive materials for hybrid supercapacitors (HSCs). Herein, a two-step hydrothermal strategy was developed to grow ternary metal selenides (Zn–Co–Ni–Se) nanosheet arrays on Ni foam (NF) for HSCs. The Zn–Co–Ni–Se nanosheets uniformly covered on NF are favorable to boosting the energy storage activity because they can afford abundant pores, which is beneficial to increase the contact areas and promote ion transport. The binder-free feature can further improve the rate and cyclic performance. As an innovative binder-free electrode, the Zn–Co–Ni–Se NA@NF can deliver 2.5 C cm–2 at 3.1 mA cm–2. Strikingly, the Zn–Co–Ni–Se NA@NF//AC HSC can afford 0.13 mWh cm–2 at 1.27 mW cm–2. The capacity retention of Zn–Co–Ni–Se NA@NF//AC HSC is 92.9% after 5000 cycles at 6.4 mA cm–2. A Zn–Co–Ni–Se NA@NF//AC HSC device could successfully drive a small fan for about 150 s, displaying the bright application prospect of Zn–Co–Ni–Se@NF. Therefore, the present work demonstrates that Zn–Co–Ni–Se NA@NF is an excellent electroactive material for HSCs.