Biobattery Products from Kepok Banana Peel and Key Lime Extract Using MgSO4 and CaCl2 Electrolytes with ABC Biobattery Standards of AA Size

This study aims to investigate the potential of kepok banana peel (Musa paradisiaca L.) and key lime (Citrus amblycarpa) as raw materials for biobattery production and to evaluate the effects of KOH activation concentration and the addition of the ionic salts CaCl₂ and MgSO₄ on biobattery performance. Kepok banana peel was dried, ground into powder, and chemically activated using KOH solutions with concentrations ranging from 0.2 M to 1.0 M. The electrolyte was prepared by mixing key lime extract with 15 g of either CaCl₂ or MgSO₄, followed by the addition of activated banana peel powder. The resulting electrolyte mixture was packed into empty AA battery casings to fabricate the biobattery cells. The fabricated biobatteries were evaluated for pH, output voltage, loaded voltage, and operating time using a 2.2 V LED load. The results showed that the biobattery activated with 0.6 M KOH and supplemented with MgSO₄ exhibited the best performance, producing a maximum output voltage of 3.01 V (two cells connected in series), a loaded voltage of 1.75 V, and an operating time of 10 h 31 min. In contrast, activation concentrations that were either too low (0.2 M) or too high (1.0 M) reduced biobattery performance because insufficient or excessive ions hindered the electrochemical reactions. Furthermore, MgSO₄ was more effective than CaCl₂ in improving electrolyte conductivity and ionic stability. These findings indicate that organic waste, such as kepok banana peel and key lime, has considerable potential as a raw material for environmentally friendly biobatteries.