Preparation of Polyethylene Oxide and Polyvinyl Alcohol Blended Polymer Electrolyte Membrane Using Water as Solvent for Solid‐State Supercapacitors

ABSTRACT This report presents the feasibility of using water as a solvent to prepare polymer electrolyte membranes (PEMs) and their application in the fabrication of solid‐state supercapacitors (SSSCs). Utilizing water instead of organic solvents in the preparation of polymer electrolytes (PEs) will significantly reduce pollution/emission and production cost. Three types of water‐soluble polymer electrolytes are synthesized: polyvinyl alcohol (PVA), polyethylene oxide (PEO), and blended PVA/PEO‐based PEMs using pure water and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. The effects of composition on shrinkage rate, mechanical properties, and electrochemical properties were studied. The blended PEM with 80 wt.% PVA and 20 wt.% PEO exhibited excellent mechanical properties, minimized shrinkage rate of 28.6%, and high ionic conductivity of 4.8 × 10 −3 S cm −1 . ATR‐FTIR and X‐ray Diffraction (XRD) analyses were employed to investigate PEMs with different compositions, revealing the microstructural implication on improved ionic conductivity. SSSCs fabricated with the blended PEM and activated carbon electrodes demonstrated a remarkably low specific equivalent series resistance (ESR) of 1.3 Ω cm 2 . The cyclic voltammetry (CV) measurements revealed an ideal capacitive behavior and a high charge–discharge efficiency of 94.1%. Galvanostatic charge–discharge (GDC) curves between 0 V and 1.5 V confirmed the membrane's exceptional performance as a separator in SSSCs.