High-performance Quasi − Solid − State hybrid supercapacitor for Self − powered strain sensor based on poly (3, 4 − propylenedioxythiophene)/NiS2@Hollow carbon sphere composite and sulfonated cellulose hydrogel electrolyte

High − performance energy storage and sensing systems are rapidly evolving to meet product demands for portable and wearable electronic devices. Here, a NiS2@hollow carbon spheres (NiS2@HCS) composite protected by poly (3,4 − propylenedioxythiophene) (PProDOT) films is designed as cathode materials for supercapacitors. The designed nanocomposite reveals a specific capacitance (737C g−1 at 1 A/g) and a remarkable rate of performance. Furthermore, an alkaline hydrogel electrolyte (PVA/Sulf-CMC/KOH) based on polyvinyl alcohol (PVA) and sulfonated cellulose (Sulf − CMC) is innovatively constructed, which exhibits outstanding ionic conductivity (15.03 S m−1) for fast charge transfer and network − like highways for sufficient ion transport. Given these desirable properties, a quasi − solid hybrid supercapacitor fabricating with PProDOT/NiS2@HCS, activated carbon (AC), and PVA/Sulf − CMC/KOH delivers a maximum energy density of 54.57 Wh kg−1, a high − power density of 5142 W kg−1, and a long cycle life of 12,000 cycles with 93.29 % capacity retention at 2 A/g. Furthermore, a sensing system was constructed by combining quasi − solid − state capacitors and polymer hydrogels for monitoring human activity. This work presents a unique opportunity to construct surface reaction-oriented high-performance energy storage devices and for self − powered monitoring of human activities by combining conducting polymer − coated NiS2@HCS with hydrogel electrolytes.