2D nanosheet/3D cubic framework Ni–Co sulfides for improved supercapacitor performance via structural engineering

Abstract

The construction of multi-dimensional structured battery-type electrode materials is a promising strategy to develop high performance electrodes for supercapacitors. Herein, a series of battery-type Ni₃S₂@Co₃S₄ electrodes with different morphologies are synthesized by controlling the hydrothermal reaction time. Owing to the unique structure with independent but interconnected 2D nanosheets and 3D cubic frameworks, NCS-60 displays high conductivity, numerous active sites and good wettability behavior. It can deliver a high specific capacity of 388.9 mA h g⁻¹ (3500 F g⁻¹) at 1 A g⁻¹, an outstanding rate capacity of maintaining 88.6% at 10 A g⁻¹ and long cycle stability. The battery-type supercapacitor hybrid (BSH) device with active carbon (AC) as the negative electrode delivers an energy density of 41.8 W h kg⁻¹ at the power density of 800 W kg⁻¹. This study provides a feasible route for regulating the morphologies of in situ growth materials that improve the electrochemical performance of supercapacitors.