Stability and reversibility of LiBH4.
LiBH4 is a complex hydride and exhibits a high gravimetric hydrogen density of 18.5 wt %. Therefore it is a promising hydrogen storage material for mobile applications. The stability of LiBH4 was investigated by pcT (pressure, concentration, and temperature) measurements under constant hydrogen flows and extrapolated to equilibrium. According to the van 't Hoff equation the following thermodynamic parameters are determined for the desorption: enthalpy of reaction DeltarH = 74 kJ mol-1 H2 and entropy of reaction DeltarS = 115 J K-1 mol-1 H2. LiBH4 decomposes to LiH + B + 3/2H2 and can theoretically release 13.9 wt % hydrogen for this reaction. It is shown that the reaction can be reversed at a temperature of 600 degrees C and at a pressure of 155 bar. The formation of LiBH4 was confirmed by XRD (X-ray diffraction). In the rehydrided material 8.3 wt % hydrogen was desorbed in a TPD (temperature-programmed desorption) measurement compared to 10.9 wt % desorbed in the first dehydrogenation.
Mauron
Philippe
P
EMPA Materials Sciences and Technology, Department of Mobility, Environment and Energy, Division of Hydrogen and Energy, Uberlandstrasse 129, 8600 Dübendorf, Switzerland. philippe.mauron@empa.ch
Buchter
Florian
F
Friedrichs
Oliver
O
Remhof
Arndt
A
Bielmann
Michael
M
Zwicky
Christoph N
CN
Züttel
Andreas
A