Hydrothermally assisted Cr@Zn bimetal sulfide nanoparticles with varying calcination temperature as battery grade material for supercapattery

A newly introduced hybrid device, supercapattery has captured the attention of researchers worldwide for its potential to achieve high energy and power density. The performance of this supercapattery depends highly on the materials of the electrodes. Recent research processes: using single transition metal sulfides as electrode materials for their specific capacity and rapid charge transfer processes; however, it suffers from poor electrical conductivity. Therefore, in this work, a novel bimetal Chromium Zinc Sulfide (Cr@ZnS) was synthesized to improve the conductivity via creation of synergistic effect between Cr and Zn ions. During the preparation method, different reducing agents (KOH and NaOH) were used to study the effect of the reducing agents on the electrochemical performance of Cr@ZnS. It was perceived that addition of KOH exhibits better charge storage capacity compared to addition of NaOH as they influence the production of S2- ions during the Cr@ZnS formation. The produced Cr@ZnS was then subjected under different calcination temperatures (100 °C, 200 °C and 300 °C) to investigate its effect on Cr@ZnS performance. From this work, it was revealed that calcination deteriorates the electrochemical performance of Cr@ZnS due to occurrence of morphological evolution in Cr@ZnS. The maximum specific capacitance achieved by Cr@ZnS electrode is 1338.85 F g-1 at 3Ag-1. When the optimized Cr@ZnS electrode was coupled with AC, the device exhibited excellent energy and power density value of 29.15 Wh kg-1 and 18.85 kW kg-1, respectively with a decent capacity retention of 82% over 10,000 cycles.