V2.38Nb10.7O32.7: A V2O5–Nb2O5 mixed oxide tunnel structure related to the tetragonal tungsten bronzes

Börrnert, Carina; Carrillo‐Cabrera, W.; Simon, Paul; Langbein, H.

doi:10.1016/j.jssc.2010.02.018

Cited by 13 publications

(5 citation statements)

References 21 publications

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“…Applying long milling time was essential in increasing the lattice imperfections and mechanical deformation that were intoduced to the milled powders, and hence deduced the kinetics barrier (inset of Figure 7a). It is worth mentioing that longer milling time is responsible for modifying the thermodynamic barrier of the system upon the formation of significant volume fraction of γ-MgH 2 metastable phase (inset of Figure 7a), as suggested by many authors [27][28][29][30][31][32][33][34]. From Table 3, it can be summarized that the starting MgH 2 powders that were prepared in the present work had better hydrogenation kinetics and higher storage capacity when compared to the other reported ones that were prepared with shorter ball milling time.…”

Section: Normal-pressure Differential Scanning Calorimetrymentioning

confidence: 62%

Synergistic Effect of New ZrNi5/Nb2O5 Catalytic Agent on Storage Behavior of Nanocrystalline MgH2 Powders

2019

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Due to its availability and high storage capacity, Mg is an ideal material in hydrogen storage applications. In practice, doping Mg/MgH2 with catalyst(s) is necessary in enhancing the de/rehydrogenation kinetics and minimizing both of decomposition temperature and its related apparent activation energy. The present study proposed a new heterogeneous catalytic agent that consisted of intermetallic compound (ZrNi5)/metal oxide (Nb2O5) binary system for using with different concentrations (5−30 wt%) to improve MgH2. Doping MgH2 powders with low concentration (5, 7, 10 wt%) of this new catalytic system led to superior absorption/desorption kinetics, being indexed by the short time that is required to absorb/desorb 4.2−5.6 wt% H2 within 200 s to 300 s. Increasing the doping dose to 15–30 wt% led to better kinetic effect but a significant decrease in the hydrogen storage capacity was seen. The dependent of apparent activation energy and decomposition temperature of MgH2 on the concentration of ZrNi5/Nb2O5 has been investigated. They tended to be linearly decreased with increasing the catalyst concentrations. The results elucidated the crucial role of catalytic additives on the disintegration of MgH2 into ultrafine powders (196 nm to 364 nm diameter). The formation of such nanoparticles enhance the hydrogen diffusion and shorten the time that is required for the hydrogenation/dehydrogenation process. Moreover, this refractory catalytic system acted as a grain growth inhibitor, in which Mg/MgH2 powders maintained their submicron level during the cycle-life-test that was extended to 100 h at 200 °C.

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Section: Normal-pressure Differential Scanning Calorimetrymentioning

confidence: 62%

Synergistic Effect of New ZrNi5/Nb2O5 Catalytic Agent on Storage Behavior of Nanocrystalline MgH2 Powders

2019

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“…Among them, only the VNbO 5 compound meets the local octahedral coordination criterion. [35][36][37][38] Based on these considerations, the present investigation provides, for the first time, a detailed study of the effect of VNbO 5 on the sorption properties of magnesium hydride. The additive, prepared via the conventional route, is able to improve significantly the sorption properties of the system decreasing the desorption temperature and enhancing the cyclability of the whole system.…”

Section: Introductionmentioning

confidence: 94%

Remarkable hydrogen storage properties of MgH₂doped with VNbO₅

Valentoni

Mulas

Enzo

et al. 2018

Phys. Chem. Chem. Phys.

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The present work concerns the catalytic effect of VNbO, a ternary oxide prepared via a solid-state route, on the sorption performance of MgH. Three doped systems, namely 5, 10 and 15 wt% VNbO-MgH have been prepared by ball milling and thoroughly characterized. Hydrogen sorption, evaluated by temperature programmed desorption experiments, revealed a significant reduction of the desorption temperature from 330 °C for the un-doped sample (prepared and tested for comparison) to 235 °C for the VNbO-doped sample. Furthermore, more than 5 wt% of hydrogen can be absorbed in 5 minutes at 160 °C under 20 bar of hydrogen, which is remarkable compared to the 0.7 wt% achieved for the un-doped system. The sample doped with 15 wt% of additive, showed good reversibility: over 5 wt% of hydrogen with negligible degradation even after 70 consecutive cycles at 275 °C and 50 cycles at 300 °C. The kinetics analysis carried out by Kissinger's method exhibited a considerable reduction of the activation energy for the desorption process. Finally, pressure-composition-isotherm experiments conducted at three different temperatures allowed estimating the thermodynamic stability of the system and shed light on the additive role of VNbO.

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“…LeBail refinement of the diffraction pattern revealed lattice parameters of a = 17.3658( 12 S2a). 41 The diffraction peaks with hkl indices (001) and (002) displayed enhanced intensities with respect to the calculated intensities. This was most visible in the LeBail fit of this material in Figure S2a, where the fit included a (001) texture term.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Herein, we report the electrochemical characterization of V 4 Nb 18 O 55 (which possesses a distorted T-Nb 2 O 5 structure) in Mg 2+ electrolytes. The structure was solved in 2010 by Borrnert et al 41 and was first reported as a high-power anode material in Li-ion batteries by Qian et al in 2018. 38 V 4 Nb 18 O 55 shows the intrinsic ability to reversibly intercalate Mg 2+ with lower hysteresis in comparison to known oxide materials (0.5 vs 0.7 V).…”

Section: ■ Introductionmentioning

confidence: 99%

Probing Mg Intercalation in the Tetragonal Tungsten Bronze Framework V₄Nb₁₈O₅₅

et al. 2020

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While commercial Li-ion batteries offer the highest energy densities of current rechargeable battery technologies, their energy storage limit has almost been achieved. Therefore, there is considerable interest in Mg batteries, which could offer increased energy densities compared to Li-ion batteries if a high-voltage electrode material, such as a transition metal oxide, can be developed. However, there are currently very few oxide materials which have demonstrated reversible and efficient Mg 2+ insertion and extraction at high voltages; this is thought to be due to poor Mg-ion diffusion kinetics within the oxide structural framework. Herein, the authors provide conclusive evidence of electrochemical insertion of Mg 2+ into the tetragonal tungsten bronze V4Nb18O55, with a maximum reversible electrochemical capacity of 75 mA h g −1 , which corresponds to a magnesiated composition of Mg4V4Nb18O55. Experimental electrochemical magnesiation/de-magnesiation revealed a large voltage hysteresis with charge/discharge (1.12 V vs Mg/Mg 2+ ); by limiting magnesiation to a composition of Mg2V4Nb18O55, this hysteresis can be reduced down to only 0.5 V. Hybrid-exchange Density Functional Theory (DFT) calculations suggest that a limited number of Mg sites are accessible via low-energy diffusion pathways, but that larger kinetic barriers need to be overcome to access the entire structure. The reversible Mg-ion intercalation involved concurrent V and Nb redox activity and changes in crystal structure, confirmed by an array of complimentary methods including powder X-ray diffraction, X-ray absorption spectroscopy, and energy-dispersive X-ray spectroscopy. Consequently, It can be concluded that the tetragonal tungsten bronzes show promise as intercalation electrode materials for Mg batteries. 30 the development of new energy storage technologies is par-31 amount. While Li-ion batteries have achieved great com-32 mercial success, 1 and are the most energy-dense recharge-33 able storage technology for portable applications, the tech-34 nology already heavily optimized, and future increases in35 energy density are predicted to be incremental. 2 Therefore,36 there is a need to develop new, low cost, and sustainable 37 battery chemistries for applications such as future electric 38 vehicle and grid storage. Mg metal anodes have a lower pro-39 pensity to form dendrites (that can cause cell failure) from 40 stripping and plating, which means that it could be used di-41 rectly as a metallic anode, 3-5 which would offer up to a five-42 fold increase in anodic volumetric energy density (Mg metal 43 = 3833 mA h cm −3 ) compared to Li-ion graphite anodes 44 (∼800 mA h cm −3 ), leading to an overall doubling in energy 45 density if a suitably high-energy density electrode material 46 can be found. 6 In comparison to Li + , the divalent ion Mg 2+ 47 transfers twice the charge (2 e − per Mg 2+ ion) when moving 48 between anode and cathode. This phenomenon decouples 49 the effect of electronic changes from the availability of va-50 cant sites in th...

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V2.38Nb10.7O32.7: A V2O5–Nb2O5 mixed oxide tunnel structure related to the tetragonal tungsten bronzes

Cited by 13 publications

References 21 publications

Synergistic Effect of New ZrNi5/Nb2O5 Catalytic Agent on Storage Behavior of Nanocrystalline MgH2 Powders

Synergistic Effect of New ZrNi5/Nb2O5 Catalytic Agent on Storage Behavior of Nanocrystalline MgH2 Powders

Remarkable hydrogen storage properties of MgH₂doped with VNbO₅

Probing Mg Intercalation in the Tetragonal Tungsten Bronze Framework V₄Nb₁₈O₅₅

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V2.38Nb10.7O32.7: A V2O5–Nb2O5 mixed oxide tunnel structure related to the tetragonal tungsten bronzes

Cited by 13 publications

References 21 publications

Synergistic Effect of New ZrNi5/Nb2O5 Catalytic Agent on Storage Behavior of Nanocrystalline MgH2 Powders

Synergistic Effect of New ZrNi5/Nb2O5 Catalytic Agent on Storage Behavior of Nanocrystalline MgH2 Powders

Remarkable hydrogen storage properties of MgH2doped with VNbO5

Probing Mg Intercalation in the Tetragonal Tungsten Bronze Framework V4Nb18O55

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Remarkable hydrogen storage properties of MgH₂doped with VNbO₅

Probing Mg Intercalation in the Tetragonal Tungsten Bronze Framework V₄Nb₁₈O₅₅