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

Abstract

The evolution of diborane accompanying H 2 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 LiNH 2 is doped into a 3LiBH 4 /MnF 2 composite and the decomposition properties are investigated. The results show that after doping LiNH 2 , 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.% LiNH 2 -doped 3LiBH 4 /MnF 2 composite. These improvements in the decomposition performance are mainly attributed to the prevention of the formation of B–H–B bonds for B 2 H 6 and the destabilization of B–H bonds in borohydrides by the interaction of BH 4 − and NH 2 − . ► LiNH 2 -doping improves the decomposition properties of 3LiBH 4 /MnF 2 composite. ► Both decrease in decomposition temperature and suppression of B 2 H 6 are achieved. ► 3LiBH 4 /MnF 2 composite doped with 5 wt.% LiNH 2 releases pure H 2 at 95–140 °C. ► These improvements are attributed to the interaction of BH 4 − and NH 2 − .