The storage of hydrogen is an essential brick in the scope of using hydrogen vector for either mobile or stationary applications for energy storage. The thesis subject concerns the storage of hydrogen in materials known as hydrides, which has the advantage over the other two modes of conventional storage (in the form of compressed gas or liquid) to be safer and more compact. Both conventional technologies have also reached their limits and solid storage is the only way forward, especially to meet the demands of weight and compactness of the automotive application. For now, among these materials, the metal hydrides (already used for applications) have either mass storage capacity too low or operating conditions of temperature too high (> 300 ° C).
Recent research has shown encouraging results regarding the chemical hydrides based on lithium, boron, sodium and aluminum. A significant first step took place in 1998 [1] showing reversibility of 5.6 wt% of hydrogen on alanates (NaAlH4) by using an efficient catalyst (TiCl3). More recently, interesting results have been obtained for LiBH4 and MgH2 system [2], with more than 10 wt% of proven reversibility, but operating at 300 ° C. The positive effects of coupling to amides (LiNH2) have been shown by decreasing the operating temperature between 100 and 200 °C, but with smaller capacities [3]. Obtaining a reversibility of complex hydrides in a window of temperature and pressure not too far from the atmospheric conditions is new, however, the materials are still not entirely satisfactory. They suffer from a disproportionation phenomenon (separation of chemical species) and the kinetics and operating conditions are still too far from the optimal conditions to be used in a vehicle (charging in less than 5 minutes, at lower temperatures than 100 °C and at pressures lower than 30 bar).
The proposed subject within this framework aims to develop solutions allowing for this type of complex hydrides to operate in a temperature range and pressure more compatible with targeted mobile applications. The aim of the thesis is to implement in particular nanoconfinement and catalysis techniques in order to improve the functioning of LiBH4-MgH2-LiNH2 system [4].
In addition to a thorough research on the reaction mechanisms of these materials, one must also anticipate how to get their production costs compatible with the technical and economic constraints of the hydrogen storage application.
[1] Bogdanovic B, Schwickardi M, Ti-doped alkali metal aluminium hydrides as potential novel reversible hydrogen storage materials, J Alloys Comp. vol. 253, pp. 1-9, 1997.
[2] Barkhordarian G, Klassen T, Dornheim M, Bormann R., Unexpected kinetic effect of MgB2 in reactive hydride composites containing complex borohydrides, J Alloys Comp, vol. 440, pp. 18-21, 2007
[3] Eymery, J.B.; Truflandier, L.; Charpentier, T.; Chotard, J.N.; Tarascon J.M.; Janot, R. Studies of covalent amides for hydrogen storage systems: structures and bonding of the MAl(NH2)4 phases with M=Li,Na,K., J. Alloys Compd. (2010), 503, 194
[4] Brun, N.; Janot, R.; Sanchez, C.; Deleuze, H.; Gervais, C.; Morcrette, M.; Backov, R.; Preparation of LiBH4@carbon micro–macrocellular foams: tuning hydrogen release through varying microporosity, Energy Environ. Sci. (2010), 3, 824
This position is open until it is filled.
Department: Département Thermique Biomasse et Hydrogène (LITEN)
Start Date: 01-10-2015
ECA Code: SL-DRT-15-0544
Contact: vasile.iosub<στο>cea.fr