Development of SPVDF‐HFP/PEG‐MnO2‐based proton‐conducting composite polymer electrolyte towards proton battery applications

Abstract This study focuses on the fabrication of proton‐conducting composite membranes by the inclusion of poly(ethylene glycol) (PEG)‐MnO 2 hybrid filler within a sulfonated poly(vinylidene fluoride)‐ co ‐hexafluoropropylene (SPVDF‐HFP) polymer matrix and evaluates their suitability as a solid polymer electrolyte for proton battery applications. The structural, morphological, thermal and mechanical properties of the membrane were analyzed using various techniques, whereas the electrochemical properties such as proton conductivity and electrochemical stability of the membrane were measured using electrochemical impedance spectroscopy, linear sweep voltammetry and and cyclic voltammetry, techniques. The results revealed that the incorporation of PEG‐MnO 2 within the SPVDF‐HFP matrix rearranged the α ‐phase crystal structure of PVDF‐HFP into the β ‐phase by reducing crystallinity and significantly enhancing the thermal ( T max at 478 °C; T m at 144.5 °C) and mechanical (tensile stress of 27.9 MPa; modulus of 2070 MPa) stability of the membrane, showing its durability and stability for high‐temperature applications. Furthermore, the tendency of PEG‐MnO 2 to form multiple hydrogen‐bonding sites within the polymer matrix results in improved porosity, water uptake and proton conductivity of the membrane. The linear sweep voltammetry and cyclic voltammetry results confirm the excellent electrochemical stability (2.5 V) of the membrane. A primary battery assembled using the developed membrane exhibits an open‐circuit voltage of 1.4 ± 0.03 V, which remains stable for over 48 h, further highlighting the membrane's potential for high‐performance proton battery applications. © 2025 Society of Chemical Industry.