Rapid synthesis of MnS/NiCo-LDH heterostructures for high-performance supercapacitors

Abstract

As a kind of semiconductor with wide band gaps, MnS has received wide attention for supercapacitors. However, its electrochemical performance is often unsatisfactory. A practical solution to the poor energy density of supercapacitors is the rational design of heterostructure electrode materials. Here, a MnS-supported NiCo-LDH (MnS/NiCo-LDH) composite electrode was prepared using a convenient two-step electrodeposition technique and its electrochemical behavior was analyzed. The NiCo-LDH material was tightly adhered to the MnS nanoparticle substrate, expanding the reaction species and decreasing the thicknesses of NiCo-LDH. As a growth basis for NiCo-LDH, rough MnS is more conducive to the compact growth of NiCo-LDH. Benefiting from the porous channels in the three-dimensional net-like nanostructure, the MnS/NiCo-LDH composite electrode exhibits a high capacitance of 2022 F g⁻¹ at 1 A g⁻¹ and good cycling stability (78.0% remaining over 2000 cycles). Moreover, an asymmetric supercapacitor (ASC) assembled with MnS/NiCo-LDH and activated carbon achieves an energy density of 78.67 W h kg⁻¹ at 804.8 W kg⁻¹, and the device still retains 94.0% of its initial capacitance after 5000 cycles. The superb electrochemical performance benefits from the synergistic effect between MnS nanoparticles and NiCo-LDH nanosheets as well as its unusual porous structure. The attained results suggest that the well-designed MnS/NiCo-LDH electrode has great potential to meet the requirements for advanced energy storage devices.