Polythiophene Coating-encapsulated CoNi2S4@HCS for quasi-solid-state hybrid supercapacitors with gel electrolyte containing gelatin

Abstract

Supercapacitors play a crucial role in energy storage applications due to their high energy and power densities. In this context, synthesizing composites such as: poly(3,4propylenedioxythiophene)/CoNi2S4@hollow carbon sphere (PProDOT/CoNi2S4@HCS) through solid-state thermal polymerization and hydrothermal ion exchange has gained significant attention. The PProDOT/CoNi2S4@HCS composite exhibits exceptional electrochemical performance, including a high specific capacitance of 1054 C g−1 and an initial capacity retention rate of 83.3% at 20 A g−1. This signifies that the composite can effectively store and deliver electrical energy. The composite possesses a three-dimensional core-shell structure, wherein HCS acts as a carbon-based substrate that prevents the aggregation of CoNi2S4 nanoparticles. Simultaneously, the PProDOT film ensures the structural integrity of CoNi2S4 and facilitates efficient electron/ion transfer within the composite. Furthermore, researchers have assembled a quasi-solid-state supercapacitor using the PProDOT/CoNi2S4@HCS composite and a gel electrolyte composed of polyvinyl alcohol/sulfonated cellulose/gelatin (PVA/sCMC/GEL/KOH). This supercapacitor demonstrates outstanding characteristics, such as a high energy density of 85.3 Wh kg−1, a high power density of 7957 W kg−1, and a capacity retention rate of 87.56% after 15,000 cycles at 4 A g−1. These results indicate that the composite-based supercapacitor can provide long-term stability and reliable performance under demanding operating conditions.