Effects of metastability on hydrogen sorption in fluorine substituted hydrides

Pinatel, Eugenio Riccardo; Corno, Marta; Ugliengo, Piero; Baricco, Marcello

doi:10.1016/j.jallcom.2014.01.028

Cited by 14 publications

(15 citation statements)

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“…14 However, recent ab initio calculations and Calphad modelling have predicted that the enthalpy of mixing between NaH and NaF is slightly negative ($2 kJ mol À1 ) and a single solid solution is obtainable. 18 At the same time, the authors of ref. 18 predicted that uorine substitution will increase the equilibrium decomposition temperature.…”

Section: Introductionmentioning

confidence: 99%

Fluoride substitution in sodium hydride for thermal energy storage applications

et al. 2016

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The solid-state solutions of NaH x F 1Àx (x ¼ 1, 0.95, 0.85, 0.5) have been investigated to determine their potential for thermal energy applications. Thermal analyses of these materials have determined that an increase in fluorine content increases the temperature of hydrogen release, with a maximum rate of desorption at 443 C for NaH 0.5 F 0.5 compared to 408 C for pure NaH, while pressure-compositionisotherm measurements have established a DH des of 106 AE 5 kJ mol À1 H 2 and DS des of 143 AE 5 J K À1 mol À1 H 2 , compared to 117 kJ mol À1 H 2 and 167 J K À1 mol À1 H 2 , respectively, for pure NaH. While fluorine substitution actually leads to a decrease in the stability (enthalpy) compared to pure NaH, it has a larger depressing effect on the entropy that leads to reduced hydrogen equilibrium pressures. In situ powder X-ray diffraction studies have ascertained that decomposition occurs via enrichment of fluorine in the NaH x F 1Àx composites while, unlike pure NaH, rehydrogenation is easily achievable under mild pressures. Further, cycling studies have proven that the material is stable over at least seven hydrogen sorption cycles, with only a slight decrease in capacity while operating between 470 and 520 C.Theoretically, these materials may operate between 470 and 775 C and, as such, show great potential as thermal energy storage materials for concentrating solar thermal power applications. † Electronic supplementary information (ESI) available: XRD analysis of annealed NaH x F 1Àx materials; van't Hoff plots of NaH 0.5 F 0.5 ; variation of DH and DS as function of hydrogen desorption; composition of NaH 0.5 F 0.5 as a function of temperature measured by in situ XRD. See

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Section: Introductionmentioning

confidence: 99%

Fluoride substitution in sodium hydride for thermal energy storage applications

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“…room temperature and p(H 2 ) = 1 bar) 52. Therefore, an entropy effect may contribute to the increased solubility of NaBH 4 in h−LiBH 4 .…”

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A thermodynamic investigation of the LiBH₄–NaBH₄ system

et al. 2016

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The LiBH 4 -NaBH 4 pseudo-binary system has been investigated by X-ray diffraction, temperatureprogrammed photographic analysis, and differential scanning calorimetry, in order to establish the phase diagram. The polymorphic orthorhombic-to-hexagonal phase transition of LiBH 4 was observed at 94 °C in samples containing NaBH 4 , i.e. 15 °C lower than for pure LiBH 4 , which indicates the dissolution of sodium into LiBH 4 . The formation of solid solutions was confirmed by powder X-ray diffraction measurements performed as a function of temperature. A new eutectic composition between Li 0.65 Na 0.35 BH 4 and Li 0.70 Na 0.30 BH 4 , with a melting temperature of 216 °C, is observed. Ab-initio calculations have been performed to establish the relative stabilities of the pure compounds in orthorhombic, hexagonal and cubic structure. The obtained experimental and calculated data were compared with available literature values and they were used for a thermodynamic assessment of the LiBH 4 -NaBH 4 system by the Calphad method. The enthalpy of mixing for solid and liquid solutions has been estimated on the basis of experimental data.The LiBH4-NaBH4 pseudo-binary system has been investigated by X-ray diffraction, temperature programmed photographic analysis and differential scanning calorimetry, in order to establish the phase diagram. Ab-initio calculations have been performed to establish the relative stabilities of the pure compounds in various structures. The obtained experimental and calculated data were compared with available literature values and they were used for a thermodynamic assessment of the LiBH4-NaBH4 system by the Calphad method.

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“…to provide solid solutions, [102][103][104][105][106][107][108][109][110][111] i.e. cationic or anionic fully disordered structures, as well as hydrogen-fluorine exchange which improved the hydrogen desorption reactions.…”

Section: Among Many Tailoring Routes Cation and Anion Substitution In Borohydrides Has Been Demonstratedmentioning

confidence: 99%

Solid-State Hydrogen Storage: Materials, Systems and the Relevance of a Gender Perspective

Em¹,

Barale²,

Corno³

et al. 2021

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This paper aims at addressing the exploitation of solid-state carriers for hydrogen storage, with attention paid both to the technical aspects, through a wide review of the available integrated systems, and to the social aspects, through a preliminary overview of the connected impacts from a gender perspective. As for the technical perspective, carriers to be used for solid-state hydrogen storage for various applications can be classified into two classes: metal and complex hydrides. Related crystal structures and corresponding hydrogen sorption properties are reviewed and discussed. Fundamentals of thermodynamics of hydrogen sorption evidences the key role of the enthalpy of reaction, which determines the operating conditions (i.e. temperatures and pressures). In addition, it rules the heat to be removed from the tank during hydrogen absorption and to be delivered to the tank during hydrogen desorption. Suitable values for the enthalpy of hydrogen sorption reaction for operating conditions close to ambient (i.e. room temperature and 1-10 bar of hydrogen) are close to 30 kJ·molH2 1. The kinetics of hydrogen sorption reaction is strongly related to the microstructure and to the morphology (i.e. loose powder or pellets) of the carriers. Usually, kinetics of hydrogen sorption reaction is rather fast, and the thermal management of the tank is the rate determining step of the processes. As for the social perspective, various scenarios for the applications in different socio-economic contexts of solid-state hydrogen storage technologies are described. As it occurs with the exploitation of other renewables innovative technologies, a wide consideration of the social factors connected to these processes is needed to assess the extent to which a specific innovation might produce positive or negative impacts in the recipient socio-economic system and to explore the potential role of the social components and dynamics in fostering the diffusion of the innovation itself. Attention has been addressed to the gender perspective, in view of the enhancement of hydrogen-related energy storage systems, intended both in terms of the role of women in triggering the exploitation of hydrogen-based storage as well as to the impact of this innovation in their current conditions, at work and in daily life.

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Effects of metastability on hydrogen sorption in fluorine substituted hydrides

Cited by 14 publications

References 21 publications

Fluoride substitution in sodium hydride for thermal energy storage applications

Fluoride substitution in sodium hydride for thermal energy storage applications

A thermodynamic investigation of the LiBH₄–NaBH₄ system

Solid-State Hydrogen Storage: Materials, Systems and the Relevance of a Gender Perspective

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Effects of metastability on hydrogen sorption in fluorine substituted hydrides

Cited by 14 publications

References 21 publications

Fluoride substitution in sodium hydride for thermal energy storage applications

Fluoride substitution in sodium hydride for thermal energy storage applications

A thermodynamic investigation of the LiBH4–NaBH4 system

Solid-State Hydrogen Storage: Materials, Systems and the Relevance of a Gender Perspective

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A thermodynamic investigation of the LiBH₄–NaBH₄ system