Evaluation of Carbon-Based EDLC with PVA Gel Polymer Electrolyte for Integrated Flexible Solar Energy Conversion and Storage Devices

The increasing demand for renewable energy and miniaturized electronics, such as wearables, highlights the limitations of bulky crystalline solar panels. To address this, a flexible device integrating solar energy conversion and storage was developed, comprising a dye-sensitized solar cell (DSSC) with a TiO2 photoanode and a symmetric electric double-layer capacitor (EDLC) with carbon electrodes for rapid energy storage. The surface morphology and chemical composition of the electrodes were analyzed using SEM, EDX, and XRD. Results confirmed a uniform distribution of TiO2 with high crystallinity in the anatase phase, while the activated carbon-multiwalled carbon nanotube composite electrode exhibited a highly porous structure. The PVA-H3PO4 gel polymer electrolyte extended the EDLC's potential window to 3.6 V, with an ionic conductivity of 9.68 × 10-5 S cm⁻¹ which requires further optimization for industrial applications. The EDLC achieved a specific capacitance of 20 μF/g, an energy density of 3.60 × 10-5 Wh/kg, and a power density of 195.98 W/kg, as determined by cyclic voltammetry and galvanostatic charge-discharge tests. The DSSC exhibited an open-circuit voltage of 0.349 V. The integrated device utilized flexible, lightweight ITO-PEN plastic current collectors, enhancing its flexibility and portability. Mechanical tests, including bending at angles exceeding 90°, showed no significant degradation or structural damage, demonstrating excellent flexibility and mechanical stability. This study underscores the potential of flexible hybrid energy devices fabricated via simple methods to meet the growing energy demands of next-generation electronics.