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Reaction Rates in Ionic Solutions
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Redox flow batteries are increasingly used to store renewable energy, but their commercial viability depends on selecting suitable redox species and ion‑exchange membranes. The study aims to synthesize a robust PVA‑silica composite membrane and demonstrate its use in an aqueous hybrid redox flow battery. The authors fabricated a proton‑conducting, thermally cross‑linked PVA‑silica membrane with uniformly distributed silica channels, and evaluated it in a hybrid RFB using PPS and vanadium salts, performing rate‑performance, cycling, polarization, and OCV analyses. After 100 charge/discharge cycles, the membrane achieved 95 % coulombic, 61 % voltage, and 57 % energy efficiencies at 50 mA cm⁻², demonstrating superior performance for a functional‑group‑free proton‑conducting membrane.
The use of redox flow batteries (RFBs) has become popular for preserving renewable energy. For widespread commercialization, the appropriate selection of redox-active species and ion exchange membranes (IEM) is essential. Herein, we synthesized a robust PVA-Silica (PVA-SiO2) composite membrane and demonstrated its essential use in an aqueous hybrid RFB. A proton-conducting, chemically and physically stable membrane was created by combining the traditional hydrophilicity of PVA with well-defined interconnecting ion-conducting channels produced by uniformly distributed silica particles. We believe that thermal crosslinking ensured substantial dimensional and chemical durability, whereas silica permitted good ionic conductivity. The utility of the membrane was proved in a hybrid redox flow battery consisting of newly synthesized 1,4-phenoxy bis-propane sulfonic acid (PPS) and vanadium (III) salt in 2 M H2SO4. A detailed battery analysis was carried out with a rate performance study, cycling test, polarization curve, and OCV. Over 100 charge/discharge cycles, it demonstrated 95% coulombic efficiency, 61% voltage efficiency, and 57% energy efficiency at a current density of 50 mA cm-2, indicating the best utility of an oxidatively susceptible functional group-free robust proton conducting membrane.