The effect of rice husk ash silica (SiO2) on the structural and electrical properties of the poly (methyl methacrylate) (PMMA) / 50% epoxidized natural rubber (ENR 50)-based electrolytes films

Previously, the brittle issues of poly(methyl methacrylate) (PMMA) films was solved by blending it with epoxidized natural rubber (ENR 50). The ionic conductivity of the polymer electrolyte (PE) system achieved ⁓10-5 S cm-1, but it is still inadequate for energy storage systems. The incorporation of plasticizers has been successful in solving this issue, though at the expense of its mechanical strength. In contrast, the addition of filler was shown to improve the flexibility and ionic conductivity of PE while maintaining its mechanical properties. Therefore, in this study, different amounts of silica (SiO2) filler from rice husk ash (RHA) (i.e., 0.25, 0.5, 0.75, and 1 wt.%) were incorporated into the PMMA/ENR 50-based PE system using solution casting technique. The SiO2 with an average particle size of 75.76 micrometers was extracted from RHA using the precipitation method. The structure and purity of the silica were confirmed using Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS), respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies confirm the amorphosity of the silica. Meanwhile, the effects of adding the different percentage of silica from RHA on the structural and electrical properties of the PMMA/ENR 50-based electrolyte films were analyzed by using FTIR and electrochemical impedance spectroscopy (EIS), respectively. Flexible and freestanding film of PMMA/ENR 50-based electrolyte at highest ionic conductivity of 1.37×10-3 S cm-1 was observed with addition of up to 0.5 weight % of SiO2. This was due to the increased amorphousness caused by the polymer-filler interaction, as well as the presence of a new Li ions conducting pathway caused by the saltfiller interaction, confirmed by FTIR analysis. Thus, the preparation of flexible and highly conducting silica doped PMMA/ENR 50-based PE films in this study aligns with the objectives of the 12th Shared Prosperity Vision for 2030 (KEGA12), and Sustainable Development Goals 7 (SDG7).