Paper
Kinetic Analysis for Hydrogen Absorption and Desorption of MgH2-Based Composites
- Authors:
- Motoki Shimada; Hisashi Tamaki; Eiji Higuchi; Hiroshi Inoue
- Abstract
- Hydrogen absorption-desorption properties at various temperatures for three MgH2-based composites, MgH2-Ni, MgH2-Ni-Si and MgH2-Ni-Ni2Si, were evaluated, and the most plausible reaction model and the rate-determining process for hydrogen absorption and desorption were determined for each composite. For each composite all hydrogen absorption curves at over 150 °C best fitted the three-dimensional diffusion-controlled contracting volume (CV-diffusion) model whose rate-determining step was hydrogen diffusion through the hydrogenated phase. Activation energy for hydrogen absorption was decreased in the order of MgH2-Ni-Si > MgH2-Ni-Ni2Si > MgH2-Ni. The hydrogen desorption rates of these composites also were significantly improved compared to the ball-milled MgH2. The three-dimensional CV model whose rate-determining step was the movement of the metal/hydride interface at a constant velocity was most closely fit for the hydrogen desorption curves at over 250 °C for three composites were most fitted. Activation energy for hydrogen desorption was decreased in the order of MgH2-Ni > MgH2-Ni-Si > MgH2-Ni-Ni2Si. Thus, the ball-milling of MgH2 with Ni and Ni2Si also greatly improved hydrogen absorption-desorption properties compared to ball-milled MgH2.
- Keywords
- Hydrogen Storage Material; Mechanochemical Method; Magnesium Hydride; Ni2Si; Hydrogen Absorption-Desorption
- StartPage
- 64
- EndPage
- 71
- Doi