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Pseudo-Binary Phase Diagram of LiNH2-MH (M = Na, K) Eutectic Mixture
Pranjal Pathak1, Kriti Shrivastava1,2, Takayuki Ichikawa3
1Centre for Renewable Energy & Storage, Suresh Gyan Vihar University, Jagatpura, Jaipur 302017, India.
Molecules (Basel, Switzerland)
|July 9, 2022
Summary
Researchers explored lithium amide (LiNH2) combined with sodium hydride (NaH) and potassium hydride (KH) for improved hydrogen storage. Eutectic interactions significantly lowered operating temperatures, enhancing hydrogen absorption and release kinetics for cleaner energy applications.
Area of Science:
- Materials Science
- Chemical Engineering
- Energy Storage
Background:
- Hydrogen energy is a clean alternative but lacks efficient storage solutions.
- Solid-state systems like lithium amide (LiNH2) offer high storage capacity but require impractically high temperatures for hydrogenation/dehydrogenation.
- Existing LiNH2 systems need modification to lower operational temperatures for practical applications.
Purpose of the Study:
- To investigate the effect of combining lithium amide (LiNH2) with sodium hydride (NaH) and potassium hydride (KH) on hydrogen storage properties.
- To determine if these amide-hydride systems exhibit lower operating temperatures for hydrogenation and dehydrogenation.
- To explore the underlying mechanisms, including eutectic melting, that influence the performance of these novel hydrogen storage materials.
Main Methods:
- Systematic thermal studies of LiNH2-NaH and LiNH2-KH mixtures at various molar ratios.
- Plotting of pseudo-binary phase diagrams to identify eutectic compositions.
- Morphological studies to investigate the reaction mechanisms and atomic mobility.
- Analysis of hydrogen absorption and desorption characteristics at reduced temperatures.
Main Results:
- Combining LiNH2 with NaH and KH substantially lowers hydrogenation temperatures compared to pure LiNH2.
- Eutectic melting was observed in LiNH2-NaH and LiNH2-KH systems, facilitating increased atomic mobility and reactivity.
- The lowest melting temperatures for eutectic compositions were 307 °C (0.15LiNH2-0.85NaH) and 235 °C (0.25LiNH2-0.75KH).
- These eutectic compositions demonstrated enhanced kinetics for hydrogen storage.
Conclusions:
- Amide-hydride systems, particularly eutectic mixtures of LiNH2-NaH and LiNH2-KH, offer a promising pathway for lower-temperature solid-state hydrogen storage.
- The eutectic phenomenon is key to improving atomic mobility and enhancing the reactivity of these materials.
- Further research into these modified systems could lead to practical hydrogen energy storage solutions.
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