High energy density hybrid supercapacitors derived from novel Ni3Se2 nanowires in situ constructed on porous nickel foam

Abstract

In this work, novel Ni₃Se₂ nanowires are synthesized in situ on the surface of nickel foam (Ni₃Se₂ NWs@NF) through a one-step hydrothermal reaction under different reaction times, and they demonstrate excellent energy storage performance for hybrid supercapacitors (HSCs). Owing to their good electron transfer capability and porous and hierarchical architecture, the as-prepared Ni₃Se₂ NWs@NF shows a high capacity of 2.6 C cm⁻² at 5 mA cm⁻² in a three-electrode cell. Even if the current density increases up to 250 mA cm⁻², its specific capacity still remains at 0.93 C cm⁻², exhibiting excellent rate capability. Furthermore, an HSC was assembled with the as-prepared Ni₃Se₂ NWs@NF as the positive electrode and activated carbon (AC) as the negative electrode, in 2 M KOH aqueous electrolyte. The Ni₃Se₂ NWs@NF//AC HSC demonstrates a high energy density of 64.4 W h kg⁻¹ at a power density of 446.8 W kg⁻¹ at 0.43 A g⁻¹ with an extended voltage of 1.6 V, along with outstanding long-term cycling stability that retains 93.9% of the initial capacity after 10 000 cycles. To the best of our knowledge, the Ni₃Se₂ NWs@NF//AC HSC developed in this work demonstrates the best capacity performance among the reported HSCs with nickel selenides as electrode materials in aqueous electrolytes. Our results manifest that the Ni₃Se₂ NWs@NF is a promising electrode material for high-performance HSCs.