Promoted hydrogen release from 3LiBH4/MnF2 composite by doping LiNH2: Elimination of diborane release and reduction of decomposition temperature

The evolution of diborane accompanying H2 release during the decomposition of transition metal borohydrides reduces the purity of evolved hydrogen and results in capacity loss during cycling. To solve the problem, a small amount of LiNH2 is doped into a 3LiBH4/MnF2 composite and the decomposition properties are investigated. The results show that after doping LiNH2, the formation of diborane during decomposition is effectively suppressed meanwhile the decomposition temperature is significantly reduced. Around 5 wt.% pure hydrogen can be released at 95–140 °C from 5 wt.% LiNH2-doped 3LiBH4/MnF2 composite. These improvements in the decomposition performance are mainly attributed to the prevention of the formation of B–H–B bonds for B2H6 and the destabilization of B–H bonds in borohydrides by the interaction of BH4− and NH2−.

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► LiNH2-doping improves the decomposition properties of 3LiBH4/MnF2 composite.
► Both decrease in decomposition temperature and suppression of B2H6 are achieved.
► 3LiBH4/MnF2 composite doped with 5 wt.% LiNH2 releases pure H2 at 95–140 °C.
► These improvements are attributed to the interaction of BH4− and NH2−.