Cao Hujun, Zhang Weijin, Pistidda Claudio, Puszkiel Julián, Milanese Chiara, Santoru Antonio, Karimi Fahim, Castro Riglos Maria Victoria, Gizer Gökhan, Welter Edmund, Bednarcik Jozef, Etter Martin, Chen Ping, Klassen Thomas, Dornheim Martin
Department of Nanotechnology, Institute of Materials Research, Helmholtz-Zentrum Geesthacht GmbH, Max-Planck-Straße 1, D-21502, Geesthacht, Germany.
Phys Chem Chem Phys. 2017 Dec 6;19(47):32105-32115. doi: 10.1039/c7cp06826c.
The 6Mg(NH)-9LiH-LiBH composite system has a maximum reversible hydrogen content of 4.2 wt% and a predicted dehydrogenation temperature of about 64 °C at 1 bar of H. However, the existence of severe kinetic barriers precludes the occurrence of de/re-hydrogenation processes at such a low temperature (H. Cao, G. Wu, Y. Zhang, Z. Xiong, J. Qiu and P. Chen, J. Mater. Chem. A, 2014, 2, 15816-15822). In this work, LiN and YCl have been chosen as co-additives for this system. These additives increase the hydrogen storage capacity and hasten the de/re-hydrogenation kinetics: a hydrogen uptake of 4.2 wt% of H was achieved in only 8 min under isothermal conditions at 180 °C and 85 bar of H pressure. The re-hydrogenation temperature, necessary for a complete absorption process, can be lowered below 90 °C by increasing the H pressure above 185 bar. Moreover, the results indicate that the hydrogenation capacity and absorption kinetics can be maintained roughly constant over several cycles. Low operating temperatures, together with fast absorption kinetics and good reversibility, make this system a promising on-board hydrogen storage material. The reasons for the improved de/re-hydrogenation properties are thoroughly investigated and discussed.
6Mg(NH)-9LiH-LiBH复合体系的最大可逆氢含量为4.2 wt%，在1 bar氢气压力下预测的脱氢温度约为64℃。然而，严重的动力学障碍的存在使得在如此低的温度下无法发生脱氢/加氢过程（H. Cao、G. Wu、Y. Zhang、Z. Xiong、J. Qiu和P. Chen，《材料化学杂志A》，2014年，第2卷，15816 - 15822页）。在本工作中，LiN和YCl被选为该体系的共添加剂。这些添加剂提高了储氢容量并加速了脱氢/加氢动力学：在180℃和85 bar氢气压力的等温条件下，仅8分钟内就实现了4.2 wt%的氢吸收。通过将氢气压力提高到185 bar以上，完全吸收过程所需的加氢温度可降低至90℃以下。此外，结果表明加氢容量和吸收动力学在几个循环中可大致保持恒定。低操作温度、快速的吸收动力学和良好的可逆性，使得该体系成为一种有前景的车载储氢材料。对脱氢/加氢性能改善的原因进行了深入研究和讨论。
