Thermo‐Electro‐Mechanical Characterization of Thermoset and Thermoplastic Blends for Composite Polymer Electrolytes

While thermoplastic polymers are commonly used in composite polymer electrolytes for load‐bearing energy storage devices, they often lose mechanical strength at elevated temperatures. Incorporating heat‐resistant thermoset polymers such as epoxy can mitigate this degradation. This study investigates the thermo‐electro‐mechanical properties of thermoplastic/epoxy blends, employing three thermoplastic polymers—Polyethylene Oxide (PEO), Polyvinyl Alcohol (PVA), and Polyvinyl Acetate (PVAc). A modified solution casting technique that retains the benefits of the conventional method, while improving electrode/thin film contact is introduced. Thin films are fabricated using various solvents: dimethyl sulfoxide (DMSO), N‐methyl‐2‐pyrrolidone (NMP), and water for PEO and PVA blends, and DMSO, NMP, and methanol for PVAc blends. Microscopy imaging is conducted to visualize surface morphology and identify potential phase separation. Simultaneous thermal analysis is employed to evaluate thermal properties, material degradation, and the presence of trapped solvent. Potentiostatic electrochemical impedance spectroscopy is employed to obtain Nyquist plots and determine the ionic conductivity. Dynamic mechanical analysis is used to obtain the thermo‐mechanical properties. Blending epoxy with a thermoplastic polymer using a compatible solvent produces materials with high ionic conductivity and enhanced thermomechanical stability. For example, a PVA/epoxy film exhibits a storage modulus of at —twice that of pure PVA—and an ionic conductivity of .