PNNL

Abstract

The formation of a chemically stable and thermally cyclable Mg(BH4)2 melt is proven to be possible through the utilization of an organic borohydride salt additive. While extensive exploration of additives for lowering the melting point and modifying the chemical stability of Mg(BH4)2 have been reported, this is the first study to use the organic borohydride salt, tetramethylammonium borohydride (TMAB), to modify the melting behavior of Mg(BH4)2. Examination of a 5:1 molar mixture of Mg(BH4)2 and TMAB, revealed a reversible melt between 180°-195°C which was reproduced for 5 thermal cycles. The mixture melt exhibited an enhanced chemical stability compared to melts of the individual Mg(BH4)2 and TMAB species. It was observed that between room temperature and 250°C (over 50°C above the melting point) the mixture releases