Hydrogen absorption and desorption by the Li-Al-N-H system
Yoshitsugu Kojima1, Mitsuru Matsumoto, Yasuaki Kawai
1Toyota Central R&D Labs, Inc., Nagakute-cho, Aichi-gun, Aichi, 480-1192, Japan. kojima@mosk.tytlabs.co.jp
The Journal of Physical Chemistry. B
|May 12, 2006
Summary
Lithium amide destabilizes lithium hexahydridoaluminate, enabling lower-temperature hydrogen release. Nano-nickel catalyst significantly enhances hydrogen storage capacity in the resulting Li-Al-N-H system.
Area of Science:
- Materials Science
- Chemical Engineering
- Hydrogen Storage
Background:
- Lithium hexahydridoaluminate (Li(3)AlH(6)) is a potential hydrogen storage material.
- Improving the dehydrogenation and rehydrogenation kinetics of metal hydrides is crucial for practical applications.
Purpose of the Study:
- To investigate the effect of lithium amide (LiNH(2)) on the hydrogen release properties of Li(3)AlH(6).
- To evaluate the hydrogen storage capacity of the modified Li-Al-N-H system, with and without a nano-nickel catalyst.
Main Methods:
- Mechanical milling of Li(3)AlH(6) and LiNH(2) in a 1:2 molar ratio to form a Li-Al-N-H system.
- Temperature-programmed desorption (TPD) to analyze hydrogen release profiles.
- Hydrogen absorption and desorption cycling tests under varying pressure and temperature conditions, with and without nano-Ni catalyst.
Main Results:
- The Li-Al-N-H system exhibited a lower dehydrogenation onset temperature compared to pure Li(3)AlH(6), indicating destabilization.
- A significant amount of hydrogen (6.9 wt %) was released from the Li-Al-N-H system between 370 and 773 K.
- The system with a nano-Ni catalyst showed improved hydrogen absorption/desorption capacities (3-4 wt %) at 473-573 K and 0.004-10 MPa, compared to the uncatalyzed system (1-2 wt %).
Conclusions:
- Lithium amide effectively destabilizes Li(3)AlH(6), facilitating lower-temperature hydrogen release.
- The addition of a nano-nickel catalyst significantly enhances the hydrogen absorption and desorption kinetics and capacity of the Li-Al-N-H system.
- The developed Li-Al-N-H material shows promise for improved hydrogen storage applications.
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