Enhancing the performance of solid-state supercapacitors: Optimizing the molecular interactions in flexible gel polymer electrolytes.

The advancement of implantable biomedical devices (IMDs) hinges on the development of biocompatible solid-state electrolytes with outstanding electrochemical performance, safety, and reliability for flexible solid-state supercapacitors. This study focuses on the development of gel polymer electrolytes (GPEs) using polyvinyl alcohol (PVA) and potassium chloride (KCl). The GPEs obtained were subjected to comprehensive characterization using a diverse range of techniques to evaluate their spectral features, morphological properties, thermal and mechanical performance, biocompatibility, ionic conductivity, and cyclic stability. What distinguishes our research is its comprehensive exploration of the profound impact of varying PVA molecular weights and PVA/KCl weight ratios on the ionic conductivity and thermal characteristics of these gels. Notably, we observed a decrease in ionic conductivity with increasing PVA molecular weight, whereas an increase in salt concentration under the same molecular weight led to higher ionic conductivity. In particular, the optimal gel electrolyte with a molecular weight (Mw) of 195,000 g/mol and a PVA/KCl weight ratio of 1/2 demonstrated a promising ionic conductivity of 3.48 ± 0.25 mS/cm. Even after 5000 cycles, it retained 88% of its initial specific capacitance. Our findings reveal that the GPEs exhibit remarkable mechanical robustness alongside unparalleled ionic conductivity, characterized by minimal interfacial resistance. Moreover, these gel electrolytes exhibit remarkable biocompatibility, evident in a cell viability test where 72.3% of cells remained unaffected after a 72-h exposure to PVA/KCl. These findings present a promising avenue towards the fabrication of stable and high-performance biocompatible gel polymer electrolytes which can be used in solid-state supercapacitors, thereby laying the foundation for their integration into flexible, safer, and wearable bio-electronics. [ABSTRACT FROM AUTHOR]