The influence of trihaloacetic acids on the hydrogen sorption properties of palladium nanoparticles-modified AB5 alloy in aprotic ionic liquid: Towards ionic liquid-based electrolytes for hydride batteries

Abstract

Binary mixtures of acetic acid/trihaloacetic acids with aprotic ionic liquid – 1-ethyl-3-methylimidazolium methanesulfonate ([EMIM][MS]) are used as electrolytes for hydrogen electrosorption measurements. Preliminary studies are performed with palladium limited volume electrode to determine optimum concentration of the acid additives for hydrogen capacity and physicochemical properties of the electrolytes. The results obtained for trichloro- and tribromoacetic acid indicate that their decarboxylation occurs after mixing with [EMIM][MS] and dissolution of palladium is observed in contact with the decomposed electrolyte. Research on hydrogen capacity of palladium nanoparticles-modified AB5-type alloy is performed in mixtures of acetic acid and trifluoroacetic acid of optimum concentration. The best electrochemical performance is demonstrated by 2 M acetic acid/[EMIM][MS] mixture. The determined value of specific capacity of the investigated hydrogen absorbing material reaches 230 mAh g−1 and is close to that previously obtained from aqueous solutions of acids or bases.