Rotational disorder in lithium borohydride

LiBH4 has been discussed as a promising hydrogen storage material and as a solid-state electrolyte in lithiumion batteries. It contains 18.5 wt% hydrogen and undergoes a structural phase transition at 381K which is associated with a large increase in rotational disorder of the [BH4](-) anion and the increase of [Li](+) conductivity by three orders of magnitude. We investigated the [BH4](-)anion dynamic in bulk LiBH4, in LiBH4-LiI solid solutions and in nano-confined LiBH4 by quasielastic neutron scattering, complemented by DFT calculations. In all cases the H-dynamics is dominated by thermally activated rotational jumps of the [BH4](-) anion in the terahertz range. The addition of LiI as well as nano-confinement favours the disordered high temperature phase and lowers the phase transition below room temperatures. The results are discussed on the basis of first principles calculations and in relation to ionic conductivity of [Li](+).

Frick, B
Koza, Mm
Boehm, M
Mutka, H
Published in:
Qens/Wins 2014 - 11Th International Conference On Quasielastic Neutron Scattering And 6Th International Workshop On Inelastic Neutron Spectrometers, 83
Presented at:
11th International Conference on Quasielastic Neutron Scattering / 6th International Workshop on Inelastic Neutron Spectrometers (QENS/WINS), Autrans, FRANCE, MAY 11-16, 2014
Cedex A, E D P Sciences

 Record created 2015-05-29, last modified 2018-09-13

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