AL-AIR SEMI-FUEL CELLS WITH SOLID ELECTROLYTES BASED ON CARBOHYDRATE POLYMERS

In this paper hydrogels based on Xanthan (a bacterial polysaccharide commercially produced by secretion from the bacterium Xanthomonas campestris in aerobic fermentation conditions) were prepared and tested as solid alkaline (KOH) and acid (HCl) electrolytes for Al-air semi-fuel cells. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarisation curves (IE) and weight loss (WL) technique were used for cell performance analysis. Results showed that high KOH and HCl concentrations (up to 8M) and xanthan/liquid solution ratios in the range 0.6-1.4 g/ml permitted the preparation of solid electrolytes stable over time, with ionic conductivities of applicative interest (10-2 S/cm). Discharge tests effected on Al/air cells evidenced promising values of energy delivered when gels made by 8 M solutions were used (up to about 50 mAh/cm2). The corrosion inhibiting effect of xanthan in acid media was also verified