Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations
Complex aluminum hydrides with high hydrogen capacity are among the most promising solid-state hydrogen storage materials. The present study determines the thermal stability, hydrogen dissociation energy, and electronic structures of alkali metal aluminum hydrides, MAlH<sub>4</sub> (M =...
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MDPI AG
2023-03-01
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| author | Rui Zhou Xiaohua Mo Yong Huang Chunyan Hu Xiaoli Zuo Yu Ma Qi Wei Weiqing Jiang |
| author_facet | Rui Zhou Xiaohua Mo Yong Huang Chunyan Hu Xiaoli Zuo Yu Ma Qi Wei Weiqing Jiang |
| author_sort | Rui Zhou |
| collection | DOAJ |
| description | Complex aluminum hydrides with high hydrogen capacity are among the most promising solid-state hydrogen storage materials. The present study determines the thermal stability, hydrogen dissociation energy, and electronic structures of alkali metal aluminum hydrides, MAlH<sub>4</sub> (M = Li, Na, K, and Cs), using first-principles density functional theory calculations in an attempt to gain insight into the dehydrogenation mechanism of these hydrides. The results show that the hydrogen dissociation energy (E<sub>d</sub>-H<sub>2</sub>) of MAlH<sub>4</sub> (M = Li, Na, K, and Cs) correlates with the Pauling electronegativity of cation M (χ<sub>P</sub>); that is, the E<sub>d</sub>-H<sub>2</sub> (average value) decreases, i.e., 1.211 eV (LiAlH<sub>4</sub>) < 1.281 eV (NaAlH<sub>4</sub>) < 1.291 eV (KAlH<sub>4</sub>) < 1.361 eV (CsAlH<sub>4</sub>), with the increasing χ<sub>P</sub> value, i.e., 0.98 (Li) > 0.93 (Na) > 0.82 (K) > 0.79 (Cs). The main reason for this finding is that alkali alanate MAlH<sub>4</sub> at higher cation electronegativity is thermally less stable and held by weaker Al-H covalent and H-H ionic interactions. Our work contributes to the design of alkali metal aluminum hydrides with a favorable dehydrogenation, which is useful for on-board hydrogen storage. |
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| spelling | doaj.art-9164b1bd734a4d8b813ddc22fb7498a12023-11-17T09:36:23ZengMDPI AGBatteries2313-01052023-03-019317910.3390/batteries9030179Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles CalculationsRui Zhou0Xiaohua Mo1Yong Huang2Chunyan Hu3Xiaoli Zuo4Yu Ma5Qi Wei6Weiqing Jiang7School of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaSchool of Mathematics and Physics, Key Laboratory for Ionospheric Observation and Simulation, Guangxi University for Nationalities, Nanning 530006, ChinaSchool of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaSchool of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaSchool of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaSchool of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaSchool of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaSchool of Physical Science & Technology, State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite Structures, Guangxi University, Nanning 530004, ChinaComplex aluminum hydrides with high hydrogen capacity are among the most promising solid-state hydrogen storage materials. The present study determines the thermal stability, hydrogen dissociation energy, and electronic structures of alkali metal aluminum hydrides, MAlH<sub>4</sub> (M = Li, Na, K, and Cs), using first-principles density functional theory calculations in an attempt to gain insight into the dehydrogenation mechanism of these hydrides. The results show that the hydrogen dissociation energy (E<sub>d</sub>-H<sub>2</sub>) of MAlH<sub>4</sub> (M = Li, Na, K, and Cs) correlates with the Pauling electronegativity of cation M (χ<sub>P</sub>); that is, the E<sub>d</sub>-H<sub>2</sub> (average value) decreases, i.e., 1.211 eV (LiAlH<sub>4</sub>) < 1.281 eV (NaAlH<sub>4</sub>) < 1.291 eV (KAlH<sub>4</sub>) < 1.361 eV (CsAlH<sub>4</sub>), with the increasing χ<sub>P</sub> value, i.e., 0.98 (Li) > 0.93 (Na) > 0.82 (K) > 0.79 (Cs). The main reason for this finding is that alkali alanate MAlH<sub>4</sub> at higher cation electronegativity is thermally less stable and held by weaker Al-H covalent and H-H ionic interactions. Our work contributes to the design of alkali metal aluminum hydrides with a favorable dehydrogenation, which is useful for on-board hydrogen storage.https://www.mdpi.com/2313-0105/9/3/179first-principles calculationsalkali metal aluminum hydridescation electronegativitydehydrogenation performanceelectronic structure |
| spellingShingle | Rui Zhou Xiaohua Mo Yong Huang Chunyan Hu Xiaoli Zuo Yu Ma Qi Wei Weiqing Jiang Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations Batteries first-principles calculations alkali metal aluminum hydrides cation electronegativity dehydrogenation performance electronic structure |
| title | Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations |
| title_full | Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations |
| title_fullStr | Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations |
| title_full_unstemmed | Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations |
| title_short | Dehydrogenation of Alkali Metal Aluminum Hydrides MAlH<sub>4</sub> (M = Li, Na, K, and Cs): Insight from First-Principles Calculations |
| title_sort | dehydrogenation of alkali metal aluminum hydrides malh sub 4 sub m li na k and cs insight from first principles calculations |
| topic | first-principles calculations alkali metal aluminum hydrides cation electronegativity dehydrogenation performance electronic structure |
| url | https://www.mdpi.com/2313-0105/9/3/179 |
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