Xanthan and κ-carrageenan based alkaline hydrogels as electrolytes for Al/air batteries.

Xanthan and κ-carrageenan were used to prepare alkaline hydrogels to be used as electrolytes in aluminium air primary batteries. Two pasty gels were obtained starting from xanthan and KOH solutions (1M and 8M), while only the 8M KOH solution permitted the formation of a stable, elastic and gumminess hydrogel with κ-carrageenan. Discharge tests, performed on three Al/air cells assembled with Al anodes, electrolyte gels and Pt based cathodes, evidenced that all hydrogels exhibited appreciable properties of Al ion conductivities, according to the following performance order: xanthan with KOH 1M<xanthan with KOH 8M<κ-carrageenan KOH 8M. Characterization measurements (XRD, Ionic conductivity by EIS, SEM-EDS) were effected on hydrogels and galvanic cells to explain the behaviour differences detected between the hydrogels.