Contacts:

Tejs Vegge, Risø DTU, 4677-5818 (tejs.vegge@risoe.dtu.dk)

http://www.risoe.dtu.dk/About_risoe/research_departments/AFM/CV/teve.aspx

The proposed low temperature structure of α-Mg(BH4)2 containing 330 atoms in the unit cell. The structure consists of a complex network of 3 different (red, green and yellow) chains.

This project is focused on understanding hydrogen transport in solid materials for sustainable and carbon-free energy storage. For energy storage applications in general - and for automotive transportation in particular - the highest possible energy (hydrogen) density is desirable. Metal borohydrides like LiBH₄ and Mg(BH₄)₂ have very high storage capacities, but the ab- and desorption of hydrogen is too slow for most practical purposes.

These materials are very difficult to study experimentally, but it is possible to obtain detailed insight into the processes which limit the transport and release of hydrogen, using large scale-computer simulations. By combining electronic structure (density functional theory) calculations with advanced statistical methods it is possible to calculate diffusion rates of both individual hydrogen atoms and BH_x groups.

In this project, you will use computer simulations to calculate the rates for the different types diffusion processes in Mg(BH₄)₂ and use this insight to locate the rate-limiting step in the macroscopic hydrogen transport - the step, which must be improved if such materials are going to be used for reversible hydrogen storage.