The conductivity properties of Manihot esculenta (Cassava)-coated zinc for zinc-air fuel cell application

Energy crisis is a worldwide issue due to serious depletion of fossil fuel. The growing demands of energy urged to explore natural renewable energy such as fuel cell, solar cell etc. Fuel cell technology with its stable performance becomes alternative energy sources considering its low cost, efficiency and environmental safety. However, the zinc anode used in fuel cell system easily corrode and eventually can decrease the performance of fuel cell. In this study, Manihot esculenta (cassava) coated on zinc anode used in zinc-air fuel cell was carried out as an approach to solve above problem and improve the properties of zinc anode. The fabrication of modified zinc anode was done in different concentration of cassava solution with different number of scans by using Electrochemical Impedance Spectroscopy (EIS). The modified zinc anode (cassava-coated, C-Z) was characterized with Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) and Four-point Probe (4PP). The stability of C-Z in concentrated potassium hydroxide (KOH) solution was also identified. The successful of coating layer was observed from FT-IR peaks which bonds of cassava appeared in C-Z spectrum. It was found that the cassava starch can be strongly coated on zinc plate with chemical coating method through SEM and EDS analysis. For stability test, some of the bonds were disappeared when cassava layer started to degrade in higher concentration of KOH solution. Through 4PP analysis, the modified zinc anode was found to have higher conductivity (0.2942 Scm-1) than unmodified zinc anode (0.1554 Scm-1). The conductivity was found increased with number of scans of 5 scans. For cyclic voltammogram, the anodic and cathodic peak were observed, highlighting the redox reaction of cassava occur in the system. Overall study suggested that the potential of Manihot esculenta (cassava) as conductive coating layer on zinc anode and the ability of cassava in enhancing the electrical conductivity of zinc anode. The application of conductive layer of cassava on zinc plate in zinc-air fuel cells might able to be possible in the future with further optimization from this study.