Thermodynamic Characterization on Hydrogen Absorption and Desorption Reactions of Lithium – Silicon Alloy

Koichi Doi; Satoshi Hino; Hiroki Miyaoka; Takayuki Ichikawa; Yoshitsugu Kojima

doi:10.4028/www.scientific.net/MSF.654-656.2815

Paper Titles

Broad-Band Vibro-Impacting Energy Harvester
p.2799

Structural Design for the Development of the Floating Type Photovoltaic Energy Generation System
p.2803

Fabrication of Nanocrystalline TiO₂ Films by Aerosol Deposition Method for Dye-Sensitized Solar Cells
p.2807

Variation of Heat Dissipation Properties of LED Packages with Thermal Vias
p.2811

Thermodynamic Characterization on Hydrogen Absorption and Desorption Reactions of Lithium – Silicon Alloy
p.2815

Hydrogen Storage in Nitrides by the Use of Ammonia as a Hydrogen Carrier
p.2819

Hydrogen Permeation Properties of Pd-Coated Ni_37.5Nb_27.5Zr₂₅Co₅Ta₅ Amorphous Membrane
p.2823

A New Concept for Alloy Design of Nb-Based Hydrogen Permeable Alloys with High Hydrogen Permeability and Strong Resistance to Hydrogen Embrittlement
p.2827

Hydrogen Permeation of Pd-Free V-Based Metallic Membranes for Hydrogen Separation and Purification
p.2831

HomeMaterials Science ForumMaterials Science Forum Vols. 654-656Thermodynamic Characterization on Hydrogen...

Thermodynamic Characterization on Hydrogen Absorption and Desorption Reactions of Lithium – Silicon Alloy

Abstract:

Lithium hydride LiH is one of the attractive hydrogen storage materials, because it stores 12.7 mass% of H2. However, H2 desorption reaction occurs over 600 °C due to the large enthalpy change of H2 desorption Ho = 181 kJ/mol H2. The purpose of this work is to control the enthalpy change of LiH to much lower value by a mechanical alloying with Si, where the Li-Si alloy is thermodynamically more stable than Li. The alloy was synthesized from Li granule and Si powder by a mechanical alloying method. The H2 absorption and desorption properties were characterized by High-Pressure Differential Scanning Calorimetry and Thermogravimetry - Differential Thermal Analysis - Mass Spectroscopy, and X-ray diffraction measurement. Pressure - Composition - Isotherm measurements were performed at 400, 450, and 500 °C to estimate the enthalpy change. From the results, it was confirmed that reversible H2 ab/desorption reactions of the Li-Si alloy were expressed as 7LiH + 3Si ↔ (3/7)Li12Si7 + (13/7)LiH + (18/7)H2 ↔ Li7Si3 + (7/2)H2 (theoretically 5.0 mass% H2) at 400 °C. From van’t Hoff plot obtained by the results of PCI measurements, the enthalpy change of the former reaction was estimated to be Ho = 103 kJ/mol H2, which is lower than that of LiH.