Fabrication of an Environmentally Friendly Bio-Battery Based on Lime (Citrus aurantifolia) and MgSO₄ as Ion Sources with Tapioca Starch as the Matrix

This study aims to develop and evaluate the performance of an environmentally friendly bio-battery based on natural materials, namely lime (Citrus aurantifolia), magnesium sulfate (MgSO₄), and tapioca starch as a biodegradable solid electrolyte matrix. Lime extract was utilized as a natural acidic electrolyte source, MgSO₄ functioned to enhance ionic conductivity, while tapioca starch served as a structural support for the solid electrolyte system.The bio-battery was synthesized by varying the volume of lime juice (1–7 mL) and the mass of MgSO₄ (1–7 g), followed by measurements of voltage, current, and solid electrolyte resistance. The results indicate that increasing the lime juice volume up to 5 mL significantly improved the electrical performance of the bio-battery, yielding a maximum voltage of 0.845 V, a current of 0.23 mA, and the lowest resistance of 15.15 kΩ. Furthermore, the addition of MgSO₄ at a fixed lime juice volume (5 mL) demonstrated optimal performance at 3 g, producing a voltage of 0.812 V, a current of 0.33 mA, and a minimum resistance of 11.48 kΩ. Increasing the MgSO₄ content beyond this optimum value resulted in higher resistance and reduced electrical output.Overall, the findings demonstrate that the optimal combination of lime extract, MgSO₄, and tapioca starch exhibits strong potential for the development of an eco-friendly bio-battery with favorable ionic conductivity characteristics based on renewable resources