Cation/anion dependence of metal ammine borohydrides/chlorides studied by ab initio calculations

Ammonia (NH3), which contains about 18 mass% of hydrogen, is regarded not only as one of the most promising hydrogen storage materials but also as an efficient carbon-free energy carrier which can be directly used by e.g. high-temperature solid oxide fuel cells. For the development of the NH3-based sustainable society, it is important to improve NH3 storage technologies. In this paper, we have studied the microscopic properties of NH3 absorption in metal borohydrides and metal chlorides by ab initio calculations. We have revealed that there is a systematic cation dependence in the NH3 absorption properties of such materials, and the properties of NH3 absorption are mainly governed by NH3-cation interactions and NH3-anion repulsions.