Non-volatile and Stretchable Polyvinyl Chloride-Based Solid-State Electrolyte for Capacitive Energy Storage

This study introduces a novel approach to address the growing demand for flexible energy storage systems in wearable and human-integrated devices. A flexible supercapacitor (SC) system is developed using a plasticized polyvinyl chloride (PVC)-derived ionogel electrolyte. The ionogel consists of PVC, dibutyl adipate (DBA) plasticizer, and 1-ethyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl)imide ([EMIM]⁺[TFSI]⁻) ionic liquid (IL), offering impressive properties such as high stretchability (~ 2050%) and non-volatility. SCs assembled with activated carbon electrodes embedded in the ionogel exhibit remarkable electrochemical performance. They attain near-100% Coulombic efficiency (CE) up to 2.0 V and a specific capacitance of up to 64.8 F g⁻¹, finely tuned by modulating the concentration of [EMIM]⁺[TFSI]⁻ IL. Significantly, the SC employing the optimized PVC-based ionogel demonstrates exceptional stability over 1000 charge–discharge cycles, maintaining both capacitance and CE. The non-volatile nature of the ionogel enhances its robustness under ambient conditions, contributing to long-term stability. Moreover, the potential integration of the PVC-based ionogel with flexible electrodes and a malleable current collector hints at the possibility of creating a highly stretchable SC system. This work advances the field of SC powering flexible electronics and accelerates their seamless integration into everyday life.