A multi-interface bimetallic sulfoselenide–selenite heterojunction as a battery-type cathode for high-performance supercapacitors

Abstract

Transition metal chalcogenides are considered to be the most promising battery-type cathodes to construct hybrid supercapacitors. The rational design and construction of multi-anion-based heterojunctions with multi-interface structures, such as sulfoselenide and oxyselenide, are significant and necessary. In this work, a bimetallic sulfoselenide–selenite heterojunction, (Ni,Co)(Se,S)₂/(Ni,Co)SeO₃, was facilely synthesized by a simple one-pot hydrothermal method using NiCo–LDH as a template. The rough surface of the nanosheet array provides more active sites and the multi-interface optimizes the electronic structure for electrochemical reactions. As a battery-type cathode for supercapacitors, the optimized (Ni,Co)(Se,S)₂/(Ni,Co)SeO₃-1 exhibits a high specific capacitance of 7.61 F cm⁻² at a current of 2 mA cm⁻². In addition, the assembled HSC device provides a high energy density of 0.59 mW h cm⁻² at a power density of 1.44 mW cm⁻² and displays a capacitance retention rate of 84.38% after 5000 charge/discharge tests. These results demonstrate a green, safe and simple method to prepare bimetallic sulfoselenide–selenite heterojunctions from LDH-based templates as high-capacity battery-type materials for hybrid supercapacitors.