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

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. A bimetallic sulfoselenide-selenite heterojunction of (Ni,Co)(Se,S)2/(Ni,Co)SeO3 was prepared from LDH-based templates as high-capacity battery-type materials for hybrid supercapacitors.