Structural, electrical, and electrochemical investigations on Cu2+ ion–conducting PVA/HPMC-based blend solid polymer electrolytes

Blend solid polymer electrolytes (BSPEs) comprising PVA/HPMC/CuSO₄ were prepared using a solution casting approach. BSPEs were synthesized with varying weight percentages of CuSO₄ (0, 10, 20, and 30 wt.%). A variety of experimental methods, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV), were used to characterize these BSPE systems. The polymer blend matrix underwent structural alterations, according to the XRD data. The standard data from JCPDS card numbers for copper sulfate matches well with the observed strong peaks of PVA/HPMC+20 wt.% of CuSO₄ BSPE. The complex that formed within the BSPE systems was detected by FTIR, indicating a positive interaction between the salt and the host polymer. The BSPE containing 20 wt.% CuSO₄ exhibited the highest ionic conductivity, reaching 5.11 × 10⁻³ S/cm at room temperature. Electrochemical stability assessments, conducted using cyclic voltammetry and linear sweep voltammetry, revealed a sufficiently wide electrochemical window for the optimized electrolyte system, confirming its suitability for battery applications.