Effect of electrolyte additives derived from natural plant extracts- Hibiscus Sabdariffa & Bidens Pilosa, on electrochemical performance of a lead-acid battery

Lead-Acid Batteries (LABs) remain a popular choice for energy storage due to their wide availability and reasonably low cost, but they exhibit a shorter cycle life and are non-eco-friendly. The objective of this study was to evaluate the discharge capacity of a flooded lead-acid battery using an electrolyte modifiedwith additives from natural plant extracts-Hibiscus Sabdariffa (H-S) and Bidens Pilosa (B-P) plants. The study utilized commercial LABs with electrolyte solutions of 100% sulfuric acid and varying volumes of plant extract solutions at con-centration of 10% (w/v), 15.86% (w/v), 30% (w/v) and 44.14% (w/v). The effect of the additives was assessed by comparing the charge-discharge cycle times, coulombic efficiency and energy efficiency. The results show the longest measured discharge time of 4.63 h at 15.86% (w/v) of H-S additive-electrolyte solution, 0.13 h longer than for the standard electrolyte. The highest coulombic efficiency (CE) was 97.3% at 44.14% (w/v) of H-S additive electrolyte solution, 10% above the standard electrolyte. The highest value for energy efficiency (EF) was 83.8% achieved in the battery with 44.14% (w/v) H-S additive electrolyte solution. The best recorded performance with B-P additive electrolyte solution was, CE of 94.6% and EF of 81.3%, obtained at 15.86% (w/v) additive concentration. It is evident from the results that bio-active compounds present in the additive solution of plant extracts influenced the electrochemical performance of the battery. The novelty of this work lies in the choice of candidate plants named, H-S and B-P for green extracts and the methodology of extraction, which is low-cost, eco-friendly and sustainable. This study contributes to fundamental understanding and strategies towards economical and eco-friendly plant electrolyte batteries.