Maximum Hydrogen Storage Capacity Research Articles

Optimized hydrogen storage properties of Ti–Zr–Mn–VFe-based alloys by orthogonal experiment for upscaled production

Ti–Mn-based hydrogen storage alloys have been widely developed for hydrogen compressors and storage because of their excellent hydrogen storage properties. However, there is still a need to develop a high-capacity hydrogen storage based on low-cost and large-scale preparation. Herein, cheap VFe80 intermetallic alloy is employed to replace the expensive V, and Ti–Zr–Mn–VFe-based alloys ((Ti1-yZry)1+xMn1.88-z(VFe)z, x = 0, 0.05, 0.1, y = 0.05, 0.1, 0.15, z = 0.34, 0.44, 0.54) with mainly C14 Laves phase structure were designed and prepared to optimize the composition by an orthogonal experiment. According to the orthogonal analysis, it is found that the maximum hydrogen storage capacity and hysteresis factor mainly are controlled by the content of VFe80 in the Ti–Zr–Mn–VFe-based alloys. The over-stoichiometry of A-side governs the plateau slope, and the content of Zr decreases hydrogen plateau pressure. The optimal Ti0.9Zr0.1Mn1.44(VFe)0.44 alloy achieves a revisable hydrogen storage capacity of 1.73 wt% with low plateau hysteresis factor (0.49) and plateau slope factor (0.73) at room temperature, the dehydrogenation enthalpy and entropy values respectively are 33.92 kJ/mol and 120.64 J/(mol∙K), which exhibits the best overall hydrogen storage properties. Furthermore, the optimal alloy was successfully produced on a large scale, which provides empirical value for upscaled production of AB2 Laves-phase hydrogen alloys.

Electrospun synthesis of polyaniline and titanium dioxide nanofibers as potential electrode materials in electrochemical hydrogen storage

To meet the imperative of advancing sustainable energy, prioritizing storage systems for clean energy, such as hydrogen, is crucial. However, challenges exist in hydrogen storage, and focusing on nanofibers that incorporate appropriate nanoparticles emerges as a promising approach to enhance storage capacity. In this study, polyaniline/polyvinyl alcohol (PANI/PVA) nanofibers and polyaniline/polyvinyl alcohol/titanium dioxide (PANI/PVA/TiO2) nanofibers were synthesized using the electrospinning method under constant conditions. After characterization of the nanofibers by various techniques, the nanocomposites were used as novel electrode materials for a first time for electrochemical hydrogen energy. Electrochemical tests were conducted on the synthesized nanofibers, and an optimal current of 1.5 mA was determined. The electrochemical analyses obtained revealed a significant improvement in the maximum hydrogen storage capacity with the presence of TiO2 nanoparticles. It increased from 654.8 mAh/g for PANI/PVA nanofibers to 1250 mAh/g for PANI/PVA/TiO2 nanofibers. The difference in storage capacity is attributed to the addition of TiO2 nanoparticles.

Influence of Zr Addition on the Microstructure and Hydrogenation Kinetics of Ti50-xV25Cr25Zrx (x = 0, 5, 7, and 9) Alloys.

Due to the poor activation performance and kinetics of Ti50V25Cr25 alloys, the element Zr was added to improve the phase structure of the alloy and achieve a high-performance hydrogen storage alloy. The Ti50-xV25Cr25Zrx (x = 0, 5, 7, and 9) system alloys were prepared by arc melting. The alloys were analyzed using an X-ray diffractometer (XRD), scanning electron microscope (SEM), and differential scanning calorimeter (DSC). The hydrogen storage capabilities of the alloys were also obtained by the Sievert volumetric method. The results indicated that the alloy with Zr added had a combination of the C15 Laves phase and the BCC phase, whereas the Zr-free alloy had a BCC single phase. The partial replacement of Zr with Ti resulted in an increase in the lattice parameters of the main phase. The hydrogen storage kinetic performance and activation of the alloys both significantly improved with an increasing Zr concentration. The time to reach 90% of the maximum hydrogen storage capacity decreased to 2946 s, 230 s, and 120 s, respectively, with the increases in Zr concentration. The initial hydrogen absorption content of the alloys increased and then decreased after the addition of the element Zr. The second phase expanded with an increasing Zr concentration, which in turn decreased the abundance of the BCC main phase. The Ti43V25Cr25Zr7 alloy showed good cycle stability and hydrogen-desorption performance, and it could absorb 90% of the maximum hydrogen storage capacity in around 230 s. The maximum hydrogen-absorption capacity of the alloy was 2.7 wt%. The diffusion activation energy of hydrogen desorption dropped from 102.67 kJ/mol to 92.62 kJ/mol.

Key technology and application of AB2 hydrogen storage alloy in fuel cell hydrogen supply system

At present, there is limited research on the application of fuel cell power generation system technology using solid hydrogen storage materials, especially in hydrogen-assisted two-wheelers. Considering the disadvantages of low hydrogen storage capacity and poor kinetics of hydrogen storage materials, our primary focus is to achieve smooth hydrogen ab-/desorption over a wide temperature range to meet the requirements of fuel cells and their integrated power generation systems. In this paper, the Ti0.9Zr0.1Mn1.45V0.4Fe0.15 hydrogen storage alloy was successfully prepared by arc melting. The maximum hydrogen storage capacity reaches 1.89 ​wt% at 318 ​K. The alloy has the capability to absorb 90% of hydrogen storage capacity within 50 ​s at 7 ​MPa and release 90% of hydrogen within 220 ​s. Comsol Multiphysics 6.0 software was used to simulate the hydrogen ab-/desorption processes of the tank. The flow rate of cooling water during hydrogen absorption varied in a gradient of (0.02 ​+ ​x) m s−1 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12). Cooling water flow rate is positively correlated with the hydrogen absorption rate but negatively correlated with the cost. When the cooling rate is 0.06 m s−1, both simulation and experimentation have shown that the hydrogen storage tank is capable of steady hydrogen desorption for over 6 h at a flow rate of 2 L min−1. Based on the above conclusions, we have successfully developed a hydrogen-assisted two-wheeler with a range of 80 km and achieved regional demonstration operations in Changzhou and Shaoguan. This paper highlights the achievements of our team in the technological development of fuel cell power generation systems using solid hydrogen storage materials as hydrogen storage carriers and their application in two-wheelers in recent years.

Effect of industrial grade raw materials and its associated impurities on first hydrogenation of BCC solid solution alloys

This study explores the effects of using industrial-grade raw materials on the hydrogen storage properties of body-centered cubic (BCC) solid solution alloys. Industrial scrap metals were chosen as the raw material, and the desired alloys were synthesized using a vacuum arc melting furnace. Instead of using pure vanadium (V), different inexpensive industrial substitutes such as low-grade vanadium (V), vanadium nitride (VN), vanadium oxide (VO), and ferrovanadium (FeV) were utilized. The crystal structure, morphology, first hydrogenation, thermodynamics, and cyclability of the prepared alloys were analyzed by using XRD, SEM-EDS, and XPS methods. The crystal structure and morphology analysis revealed multiphase alloys in all the prepared alloys and a Ti rich third phase in the VN sample, which was absent otherwise. The first hydrogenation was performed at room temperature under a hydrogen pressure of 2 MPa without any prior heat treatment. The VO alloy displayed negligible hydrogen absorption during first hydrogenation, while the V, VN, and FeV alloys showed maximum hydrogen storage capacities of 3.49 wt%, 2.47 wt%, and 2.18 wt%, respectively. The presence of oxygen hinders the activation of the VO alloy and requires two activation cycles to activate the sample. A short-term cyclability analysis showed a reversible hydrogen storage capacity of 2 wt%. The change in enthalpy of hydrogen absorption and desorption for V alloy were calculated to be −36.73 ± 8.6 and 57.34 ± 8.3 kJ/mol H2, respectively. One of the prominent advantages of utilizing scrap raw materials was the substantial reduction in overall raw material costs, which saw an impressive 95% decrease when compared to using pure raw materials. These results highlight the economic benefits of incorporating recovered industrial scrap into hydrogen storage alloys.

Stoichiometry and annealing condition on hydrogen capacity of TiCr2-x AB2 alloys

This study presents the effect of stoichiometry and annealing condition on Ti–Cr AB2-type hydrogen storage alloys. Prior to annealing the majority phase of the as-cast alloys was the C14 Laves phase, with separate Ti and Cr phases. Annealing treatment (1273 K/14 d) led to a transition from C14 to C15 Laves phase structure. Both C14 (as-cast) and C15 (annealed) cell size increased with Ti content, up to a ratio (Cr/Ti) of 1.6, due to B-site Ti substitution in the lattice up to a limit. Pressure composition isotherm (PCI) measurements demonstrated alloys containing a greater Ti content had a better maximum hydrogen storage capacity (1.5 vs. 1.03 wt%) and lower plateau pressure (9.4 vs. 15.8 bar) at 253 K. Annealing resulted in a lower storage capacity (1.05 vs. 1.49 wt%), greater plateau pressure (ca. 30 bar) and flatter plateau slope (25 % reduction in plateau slope). Reduction in hydrogen storage capacity of annealed alloys could be due to diffusion of residual Cr in the alloy into the C15 Laves phase during the annealing process, thereby changing the local composition as confirmed through X-ray diffraction (XRD).

EDA/PANI derived FeNxC with Fe-Nx active sites as room temperature hydrogen storage material

FeNxC is explored as an efficient and cost-effective hydrogen storage material. Fe/Ethylenediamine (EDA) complex formed initially is protected by (Polyaniline) PANI polymer that gets converted to FeNxC through two-step pyrolysis process. In the first pyrolysis, (Iron sulfide) FeS particles are formed, which get converted to Fe3O4 nanoparticles in second pyrolysis. Fe-Nx active sites get exposed in micro/mesoporous carbon matrix after oxide removal through acid wash. Hydrogen adsorption studies are conducted at 25–100 °C temperature, 5–30 bar pressure. The maximum hydrogen storage capacity is observed as 2.83 wt% at 26 bar, 25 °C for the two-step calcined, acid-washed FeNxC-900–800 A, which possesses large surface area of 995 m2/g, pore volume of 0.711 cm3/g when compared to FeNxC-900–800 and FeNxC-900. The adsorption mechanism, spillover occurring at covalently bonded Fe-Nx active sites and subsequent migration, diffusion to get physisorbed within porous carbon surface, leads to the enhancement in the hydrogen adsorption.

Design and mechanosynthesis of Low-Weight High-Entropy Alloys with hydrogen storage potential properties

This investigation allows designed MgAl-based Low-Weight High-Entropy Alloys (LWHEAs) with a BCC-type structure, using a MgAlTi(X)Ni system where X = Fe, Cr and Co, with hydrogen storage potential properties. The BBC-type alloys were designed considering empiric thermodynamic parameters and obtained by high-energy ball-milling. The structure, morphology, thermal stability and hydrogen sorption properties were studied. Also, the influence of Valence Electron Concentration (VECmix) and Electronegativity difference (Δχmix) parameters on the hydrogen storage capacity of alloys was evaluated. The formation of the equiatomic MgAlTiFeNi, MgAlTiCrNi and MgAlTiCoNi BCC-type LWHEAs with densities between 4.3 ≤ ρ ≥ 4.6 g cm−3 was obtained at 8 h of milling. Alloyed powders show a homogeneous elemental distribution with heterogeneous particles of different sizes and a surface area of ∼ 2 g cm−2. Under high-temperature conditions, the LWHEAs structure changes from BCC to B2. The MgAlTiCoNi alloy presented a maximum hydrogen storage capacity of 2.1% weight H2 at 473 K and 1 MPa. The hydrogen storage depended on VECmix and Δχmix parameters in LWHEAs with the same mixing Entropy.

Hydrogen storage properties of Mg0.10Ti0.30V0.25Zr0.10Nb0.25 lightweight high entropy alloy: A theoretical study

In the past several years, Mg-based high entropy alloys (HEAs) have attracted great attention in high gravimetric hydrogen storage capacity. In this work, the hydrogen storage properties of Mg0.10Ti0.30V0.25Zr0.10Nb0.25 HEA are investigated by first-principles calculations. With increasing hydrogen concentration, the structural stability of BCC and FCC hydrides decreases and increases, respectively. By comparing the lattice constants, number of hydrogenation-induced abnormal short hydrogen-hydrogen bonds and radial distribution functions of BCC and FCC hydrides, it is found that the hydrogen accommodation ability of BCC phase is weaker than that of FCC phase, and a BCC to FCC phase transformation occurs during hydrogenation process. Further total energy calculations suggest that the threshold hydrogen content of phase transformation for Mg0.10Ti0.30V0.25Zr0.10Nb0.25 is around H/M = 1.16. By phonon spectra calculation, the maximum gravimetric hydrogen storage capacity of Mg0.10Ti0.30V0.25Zr0.10Nb0.25 is predicated to be as high as 3.16 wt%, demonstrating that Mg0.10Ti0.30V0.25Zr0.10Nb0.25 HEA is a potential hydrogen storage material.

Tailoring hydrogenation and anti-oxidation properties of titanium - iron - chromium alloys by regulating zirconium content at room temperature

The effects of Fe substitution by Zr on the microstructure, hydrogen storage properties and oxidation resistance of the TiFe0.85-xCr0.15Zrx (x = 0, 0.05, 0.10, 0.15) alloys are studied in this work. It is shown that all the alloys are consisted of TiFe phase, MgZn2-type phase and minor Ti phase. The introduction of Zr causes no change for the TiFe main phase. All the alloys absorb hydrogen directly under mild conditions without any activation process. As Zr content increases, the maximum hydrogen storage capacity of the first hydrogenation increases while the reversible hydrogen storage capacity decreases. The marked change of the first hydrogenation properties may be due to the formation of the bright phase (MgZn2-type phase). The decrease of the reversible hydrogen storage capacity is due to the formation of the stable hydrides Cr2ZrH3 and TiH2, which start to decompose at around 700 °C. During the air exposure test, the alloys with higher Zr content show good oxidation resistance. For the PCT measurement, the alloys with higher Zr show lower hydrogen absorption and desorption platform pressure, which means more stable hydrides are formed during the first hydrogenation. Moreover, the rate limiting step model of the first and fifth hydrogenation processes of all the alloys has also been investigated in detail.

Computational evaluation of lithium functionalized Penta-BN2 as promising reversible hydrogen storage

Finding advanced hydrogen storage materials with high capacity and high efficiency is a key issue for hydrogen transportation and application. In this study, the first-principles calculation method is used to examine the potential of 2D pentagonal BN2 (Penta-BN2) as an excellent hydrogen storage material. The results indicate that Penta-BN2 has superior metallic and structural stable properties. The pristine Penta-BN2 is found to have weak adsorption energy for H2 molecules, which cannot meet the requirements of hydrogen storage. However, the Li-functionalized Penta-BN2 substrate is found to be relatively excellent to adsorb H2 molecules. A Li atom is bound closely to Penta-BN2 with large adsorption energy reaching more than 3.79 eV, and the 2 × 2 × 1 Penta-BN2 supercell can be suitably accommodated 4 Li atoms. 4Li-functionalized Penta-BN2 stores up to 16H2 molecules with a hydrogen gravimetric density of 8.70 wt%. The adsorption and desorption capacity of the system for H2 molecules under practical temperature and pressure conditions are investigated with semi-empirical calculations. The maximum reversible hydrogen storage capacity is up to 7.92 wt% between the practical condition of 30 atm/233 K for adsorption to 3 atm/358 K for desorption, which is better than other 2D pentagonal materials and boron-nitrogen compounds. The proposed investigations of this work illustrate that Li-functionalized Penta-BN2 is a promising hydrogen storage material with high efficiency, reversibility, and high-capacity characteristics.

Degradation and recovery properties in thermochemical hydrogen compression by using TiFe alloy

The thermochemical hydrogen compression properties and cyclic durability of titanium-iron (TiFe) alloy were investigated at various temperatures of 200, 300, 450, and 500 °C by examing the achieved maximum pressure variations and hydrogen storage capacity before and after compression cycles. The cyclic durability of the TiFe alloy-based thermochemical hydrogen compressors was different depending on the operating temperature. Below 350 °C, the TiFe alloy-based hydrogen compressors showed stable thermochemical hydrogen compression properties with constantly achieved hydrogen compression pressure, hydrogen storage capacity, and unchanged phases. On the contrary, the reached maximum pressure with heating was gradually decreased during the compression cycles at 450 and 500 °C, suggesting poor durability and degradation at the higher temperature region. During the cycles, lattice strain and dislocation density of the alloy may be induced and lead to increase plateau pressure (hysteresis) without a change in hydrogen storage capacity. However, temperature increase can cause the disproportionation of TiFe around the formed lattice strain and dislocation. Therefore, after cycles at 500 °C, the hydrogen storage capacity is reduced by 30.4%. Furthermore, phase identification by X-ray diffraction measurements and thermal analysis suggested that TiH2, Fe2Ti, and Ti2Fe phases were disproportionately generated from the initial TiFe phase as irreversible hydrogen absorption states and became the dead volume for the cyclic compression cycles. Interestingly, the recovery of the TiFe alloy phase from the disproportionated phase of TiH2, Fe2Ti, and Ti2Fe can be achieved based on the TG-DTA-MS results. Therefore, based on the above results, the degradation and recovery properties in thermochemical hydrogen compression by using TiFe alloy are well understood in this work.

Evolution of the Phase and Hydrogen Storage Properties of New-Type VTiCrFeMn High-Entropy Alloy Prepared via Mechanical Alloying

High-entropy alloys (HEAs) have ample space for composition design, so finding an ideal hydrogen storage material is a great challenge. This work used the atomic radius difference, valence electron concentration, entropy, enthalpy, and new design parameters to develop a new-type alloy with a BCC structure. The V35Ti25Cr20Fe10Mn10 alloy was selected by semi-empirical formula calculation, subsequently, the alloy was successfully synthesized by mechanical alloying, and hydrogen storage properties were evaluated. The activated sample shows an excellent kinetic performance of hydrogen absorption, but its maximum hydrogen storage capacity is only about 0.34 wt.%. The results of the PCI test show that the hydrogen absorption way may be composed of the H-solid solution in the alloy and the formation of a few hydrides, which determines the hydrogen storage capacity. Significantly, the design method reported in this paper can meet the composition design of most HEAs, which has a broad application prospect.

Composition design of (LaCeCa)1(NiMnAl)5 alloys by uniform design method and their hydrogen storage performance

Rare-earth-based AB5-type alloys are strong candidates for use in solid state hydrogen storage applications; however, their capacity needs to be improved. To efficiently optimize the hydrogen storage performance of AB5-type alloys, the effects of the substitution of Ce and Ca for La (A side) and Mn and Al for Ni (B side) on the structural properties and hydrogenation/dehydrogenation performance of the (LaCeCa)1(NiMnAl)5 alloy series were studied systematically using the uniform design method. X-ray diffraction analysis and scanning electron microscopy showed that all the designed alloys consisted of a single uniform LaNi5 phase. The atomic radii and contents of the constituent elements had a determining effect on the cell volume and properties of the alloys. The maximum hydrogen storage capacity of the (LaCeCa)1(NiMnAl)5 alloy series is approximately 1.7 wt%, which is much higher than the theoretical hydrogen storage capacity of LaNi5 (1.39 wt%).

A microfluidic proton flow reactor system: In-situ visualisation of hydrogen evolution and storage in carbon-based slurry electrodes

A Proton flow reactor (PFR) system stores energy in the form of hydrogen in porous carbon particles in slurry electrodes. However, the hydrogen storage mechanisms and the reactions in this system are not well understood. In this study, we design and fabricate a microfluidic proton flow reactor (MPFR) as a small-scale PFR to enable in-situ visualisation of the key processes underlying PFR operations. We observe the behaviour of slurries and water in both hydrogen and oxygen sides with emphasis on processes in the vicinity of membranes. We use fluorescence microscopy with quinine to visualize hydronium transport from the oxygen to the hydrogen side and employ in-situ Raman spectroscopy to analyze surface structural changes in carbon particles before and after charging. Fluorescence microscopy demonstrates the formation of hydronium ions on the oxygen side and their subsequent migration to the hydrogen side, proving that the oxygen evolution reaction occurs on the oxygen side. Raman heat maps prove the formation of carbon–hydrogen bonding in particles after they are charged with PFR. Although the MPFR is operated at non-optimal slurry concentrations to allow optical access, we demonstrate that it provides maximum hydrogen storage capacity of 0.64 wt%.

Magnesium metal nano composites- A solid state hydrogen storage material

Researchers have focused on nanostructure materials in the last decade, which can play an essential role in storing hydrogen gas. Hydrogen is a future source of energy, having handling and storage challenges. In the new generation, solid-state materials have been used to store hydrogen gas as a metal hydride. Based on materials properties, Mg hydride is the most promising material to store hydrogen in a solid-state material. The theoretical hydrogen storage capacity of magnesium hydride is 7.6 wt% making it a more suitable material for hydrogen storage in the future. Instead of having high storage capacity, magnesium's practical application as a hydride is limited due to its low kinetics and high working temperature. Aside from the less thermo-stability of bulk MgH2, to achieve the maximum hydrogen storage capacity the decomposition required a higher temperature of about 300 °C with 1 bar pressure. As a result, it is necessary to optimize the stability of hydrogen and magnesium molecules to enhance kinetic and thermodynamic properties. The critical factors in improving hydrogenation properties are decreasing particle size (nano-scale) and adding various catalysts.

Recent advancements in hydrogen storage - Comparative review on methods, operating conditions and challenges

Green hydrogen, proposed as a sustainable alternative for conventional fuels, has gained utmost importance due to its reduced carbon footprint and potential application in maintaining balance between energy generation and demand. Utilization of hydrogen-based systems are challenged by cost effective storage methods. Bio-hydrogen storage technologies using cryogenic and adsorptive methods are discussed in this review paper, along with their operating conditions and storage capacities. An analysis of operational challenges and recent advancements in hydrogen storage techniques is presented. With a storage pressure of 70 MP, cryogenic hydrogen is almost twice as dense as compressed hydrogen. Technical challenges such as material cost and explosion risk can be addressed by hydrogen adsorption on activated carbon active sites. Maximum hydrogen storage capacity are reported by activated carbon obtained from Chitosan (6.77 wt%), Bamboo (6.6 wt%) and African palm shell (6.5 wt%) at 77 K and 4–20 Mpa. Further, nanotechnology approaches are presented in detail for increasing hydrogen storage capacity in pristine Si and Mg. The future perspectives in terms of technological, and economic aspects are discussed.

Analysis of hydrogen storage mechanism in bilayer double-vacancy defective graphene modified using transition metals: Insights from Ti-BDVG(Ti)-Ti

In this study, using the first principles calculation and analysis, we found that the B-doping in double-vacancy defective graphene could effectively increase the binding energy of Ti atoms in each adsorption site, especially in the H2 adsorption site with a maximum binding energy of 8.3 eV. However, N-doped bilayer graphene (N-BLG) reduced the binding energy of Ti atoms by 88% of the adsorption sites. Given these two findings, a B- and N-doped bilayer double-vacancy-defective graphene (Ti-BDVG(Ti)-Ti) was constructed. Our findings also showed that the Ti-BDVG(Ti)-Ti outer surface and inner surface could adsorb 32 and 12H2 molecules, respectively, of which 22, 20 and 2H2 molecules are adsorbed by Kubas, electrostatic interactions and chemisorption, respectively. The hydrogen storage mechanism of Ti-BDVG(Ti)-Ti involves multiple adsorption modes, and this hydrogen storage mechanism provides a theoretical basis for the rational design of hydrogen storage materials with maximum effective hydrogen storage capacity.

Ab Initio Study of High-Capacity Hydrogen Storage in Lithium-Shrouded Honeycomb Borophene Oxide Nanosheet

Here, we investigate the hydrogen storage performance of Li alkali metal-shrouded two-dimensional (2D) honeycomb borophene oxide (h-B3O) using the Tkatchenko–Scheffler method, an accurate and parameter-free method to determine the long-range van der Waals interactions. Each Li atom can strongly bind three H2 molecules to the substrate with an average adsorption energy of −0.22 eV/H2, and the theoretical weight density of the Li-shrouded h-B3O structure can reach 9.84 wt %. In particular, a maximum hydrogen storage capacity of 12.71 wt % is achievable by moderately increasing the external pressure. Lattice thermal conductivity calculations show efficient thermal transport and good adsorption/desorption behavior of H2 molecules. Furthermore, the study of possible defects in the material showed that the hydrogen storage performance of the Li-shrouded h-B3O nanosheet is insensitive to the presence of defects in the material, which has important implications for its experimental synthesis. Our findings indicate that Li-shrouded 2D h-B3O is a promising material for reversible H2 storage.

Compositional effects on the hydrogen storage properties in a series of refractory high entropy alloys

The possible combinations in the multidimensional space of high entropy alloys are extremely broad, which makes the incremental experimental research limited. As a result, establishing trends with well-known empirical parameters (lattice distortion, valence electron concentration etc.) and predicting effects of the chemical composition change are vital to guide future research in the field of materials science. In this context, we propose a strategy to rationalize the effect of chemical composition change on the hydrogen sorption properties in a series of high entropy alloys: Ti0.30V0.25Zr0.10Nb0.25M0.10 with M = Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ta and ∅ (corresponding quaternary alloy). All materials are bcc alloys and absorb hydrogen at room temperature forming fcc or pseudo-fcc dihydride phases. The maximum hydrogen storage capacity at room temperature strongly depends on the valence electron concentration (VEC) of the alloys: the capacity is high (1.5–2.0 H/M) for low values of VEC (<4.9) whereas, a drastic fading is observed for VEC ≥4.9 which is the case for alloys with M being a late 3d transition metal. The structural analysis suggests that steric effects might not be responsible for this trend and electronic reasons may be invoked. Increasing the VEC by alloying with late 3d transition metals will fill the unoccupied valence states and the electrons from interstitial hydrogens can no longer be accommodated, which is unfavorable for hydrogen storage. Moreover, the onset temperature of desorption increases almost linearly with VEC for this composition series. These findings suggest that alloys with low VEC are more likely to become promising candidates for hydrogen storage.