Hydrogen storage thermodynamics and kinetics of as-cast Ce–Mg–Nibased alloy
Yan Qi1, Xin Zhang1, Jun Li2, Dong-liang Zhao1, Shi-hai Guo1, Yang-huan Zhang1,3
1 Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081, China 2 China Rare Earth New Material (Weishan) Co., Ltd., Jining 277600, Shandong, China 3 Collaborative Innovation Center of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, China
Hydrogen storage thermodynamics and kinetics of as-cast Ce–Mg–Nibased alloy
Yan Qi1, Xin Zhang1, Jun Li2, Dong-liang Zhao1, Shi-hai Guo1, Yang-huan Zhang1,3
1 Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081, China 2 China Rare Earth New Material (Weishan) Co., Ltd., Jining 277600, Shandong, China 3 Collaborative Innovation Center of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010, Inner Mongolia, China
摘要 The reaction kinetics of alloys based on magnesium are known to be greatly improved by the partial substitution of Mg with rare earths and transition metals, particularly Ni. The enhanced superficial hydrogen dissociation rate, the weakened Mg–H bond and the lower activation energy following element replacement are thought to be related to the better performance. The experimental alloys Ce5Mg95-xNix (x = 5, 10, 15) were smelted by the vacuum induction melting. The phase transformation and structural evolution of experimental alloys before and after reaction with hydrogen were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The cast specimens contain CeMg12, Mg and Mg2Ni phases, and the increase in Ni content results in an obvious growth of Mg2Ni phase. The isothermal and non-isothermal hydrogenation and dehydrogenation kinetics of the experimental specimens were investigated using the Sievert apparatus, differential scanning calorimetry and thermal gravimetric analyzer. The activation energy may be calculated using the Arrhenius and Kissinger equations. The experimental alloys have been shown to have good activation properties, with a reversible hydriding and dehydriding capacities of around 5.0 wt.% in the first cycle. The initial dehydrogenation temperature of MgH2 decreases from 557.5 to 537.7 K with changing Ni content from 5 to 15 at.%. The dehydrogenation activation energy also reduces from 77.09 to 62.96 kJ/mol, which explains the improved hydrogen storage performance caused by Ni substitution. It can be shown that the impact of Ni on the decomposition enthalpy of MgH2 is quite modest, with the absolute enthalpy (ΔHr) only decreasing from 78.48 to 76.15 kJ/mol.
Abstract：The reaction kinetics of alloys based on magnesium are known to be greatly improved by the partial substitution of Mg with rare earths and transition metals, particularly Ni. The enhanced superficial hydrogen dissociation rate, the weakened Mg–H bond and the lower activation energy following element replacement are thought to be related to the better performance. The experimental alloys Ce5Mg95-xNix (x = 5, 10, 15) were smelted by the vacuum induction melting. The phase transformation and structural evolution of experimental alloys before and after reaction with hydrogen were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The cast specimens contain CeMg12, Mg and Mg2Ni phases, and the increase in Ni content results in an obvious growth of Mg2Ni phase. The isothermal and non-isothermal hydrogenation and dehydrogenation kinetics of the experimental specimens were investigated using the Sievert apparatus, differential scanning calorimetry and thermal gravimetric analyzer. The activation energy may be calculated using the Arrhenius and Kissinger equations. The experimental alloys have been shown to have good activation properties, with a reversible hydriding and dehydriding capacities of around 5.0 wt.% in the first cycle. The initial dehydrogenation temperature of MgH2 decreases from 557.5 to 537.7 K with changing Ni content from 5 to 15 at.%. The dehydrogenation activation energy also reduces from 77.09 to 62.96 kJ/mol, which explains the improved hydrogen storage performance caused by Ni substitution. It can be shown that the impact of Ni on the decomposition enthalpy of MgH2 is quite modest, with the absolute enthalpy (ΔHr) only decreasing from 78.48 to 76.15 kJ/mol.
Yan Qi,Xin Zhang,Jun Li, et al. Hydrogen storage thermodynamics and kinetics of as-cast Ce–Mg–Nibased alloy[J]. Journal of Iron and Steel Research International, 2024, 31(3): 752-766.
2024, Vol. 31 
