CH3NH3][M(HCOO)3]-based 2D porous NiCo2S4 nanosheets for high-performance supercapacitors with high power densities

Abstract

Cost-effective and high-performance electrode materials for energy storage and conversion are essential for commercial applications. In this work, the influence of solvent on the morphologies of [CH3NH3][M(HCOO)3] precursors was studied to design and synthesize two-dimensional (2D) porous NiCo2S4 nanosheets with different structures. As an electrode material for supercapacitors, Microflower-NiCo2S4 exhibits excellent capacitance (1,141 F g−1 at 1 A g−1) and stability (88.2% of initial capacitance maintained after 5,000 cycles at 5 A g−1). Moreover, an asymmetric capacitor was constructed using Microflower-NiCo2S4 and porous carbon (PC) and demonstrated an energy density of 51.25 Wh kg−1 at a power density of 397.5 W kg−1. When two Microflower-NiCo2S4//PC asymmetric supercapacitors were assembled in series, the device supplied power for an alarm clock with dimensions of 6.1 × 6.1 cm2 for more than 32 min. Therefore, the preparation of metal sulfides and metal oxides with hollow structures using a [CH3NH3][M(HCOO)3]-template has potential applications in energy storage and conversion.