Influence of Various Concentrations of PVA/H₃PO₄ and PAAS/K₂SO₄ Electrolytes on the Electrochemical Performance of Graphene Micro-Supercapacitors

Abstract Flexible, solid-state supercapacitors, known for their high power density, excellent rate performance, long cycle life, high safety, and ease of fabrication, are ideal energy storage solutions for flexible and wearable electronics. Gel polymer electrolytes, with superior ionic conductivity and enhanced safety compared to liquid electrolytes, are among the most promising candidates for solid-state applications. This study investigates the performance of two different gel electrolytes (PVA/H₃PO₄ and PAAS/K₂SO₄) in graphene-based micro-supercapacitors, testing electrolyte concentrations at 3 wt%, 6 wt%, and 9 wt%. The electrochemical performance was analyzed using cyclic voltammetry. Results show that, in the PVA/H₃PO₄ system, the 6 wt% electrolyte concentration exhibited optimal performance, with capacitance increasing steadily to 177% of its initial value after 5,000 charge-discharge cycles. In contrast, the PAAS/K₂SO₄ system showed cyclic voltammetry curves closer to an ideal rectangle, indicating superior electrochemical stability. The 3 wt% concentration of this system delivered the best performance, maintaining 118% of its initial capacitance after 5,000 cycles. This study emphasizes the significant influence of electrolyte type and concentration on the performance of graphene-based micro-supercapacitors and provides valuable insights for optimizing the design of high-performance energy storage devices.