Strength testing of capacitors with liquid and polymer electrolytes based on the analysis of physicochemical and electrochemical parameters

Gel polymer electrolytes (GPEs) are extensively studied for electrochemical energy storage owing to their improved safety and mechanical stability compared to liquid electrolytes; however, electrolyte retention and long-term stability remain major challenges. In this work, a polymer-based gel electrolyte containing a conventional LiPF 6 /EC-DMC electrolyte was investigated before and after mechanical agitation in electrochemical capacitor cells. Electrochemical characterization was combined with Fourier transform infrared spectroscopy (FT-IR) and spatial mapping to evaluate electrolyte distribution and ion–polymer interactions. The as-prepared gel exhibited homogeneous electrolyte distribution, while post-agitation analysis indicated partial electrolyte loss, reflected by reduced electrolyte-related signal intensity. Despite mechanical stress, characteristic carbonyl and PF 6 − bands remained detectable throughout the gel, confirming the retention of electrochemically active ionic species. FT-IR analysis further revealed changes in C–O–C and P–F vibrations, suggesting enhanced ion–polymer interactions after electrochemical aging. Quantitative mapping showed a 30–50% decrease in electrolyte-related band intensity after agitation while preserving continuous ionic pathways. These findings demonstrate that the investigated GPE maintains sufficient electrolyte retention and electrochemical functionality after mechanical stress, highlighting its potential as a stable quasi-solid electrolyte for mechanically robust electrochemical capacitors.