High-pressure Metal Hydride Tank Research Articles

Unstable Metal Hydrides for Possible On-Board Hydrogen Storage

Hydrogen storage in general is an indispensable prerequisite for the introduction of a hydrogen energy-based infrastructure. In this respect, high-pressure metal hydride (MH) tank systems appear to be one of the most promising hydrogen storage techniques for automotive applications using proton exchange membrane (PEM) fuel cells. These systems bear the potential of achieving a beneficial compromise concerning the comparably large volumetric storage density, wide working temperature range, comparably low liberation of heat, and increased safety. The debatable term “unstable metal hydride” is used in the literature in reference to metal hydrides with high dissociation pressure at a comparably low temperature. Such compounds may help to improve the merits of high-pressure MH tank systems. Consequently, in the last few years, some materials for possible on-board applications in such tank systems have been developed. This review summarizes the state-of-the-art developments of these metal hydrides, mainly including intermetallic compounds and complex hydrides, and offers some guidelines for future developments. Since typical laboratory hydrogen uptake measurements are limited to 200 bar, a possible threshold for defining unstable hydrides could be a value of their equilibrium pressure of peq > 200 bar for T < 100 °C. However, these values would mark a technological future target and most current materials, and those reported in this review, do not fulfill these requirements and need to be seen as current stages of development toward the intended target. For each of the aforementioned categories in this review, special care is taken to not only cover the pioneering and classic research but also to portray the current status and latest advances. For intermetallic compounds, key aspects focus on the influence of partial substitution on the absorption/desorption plateau pressure, hydrogen storage capacity and hysteresis properties. For complex hydrides, the preparation procedures, thermodynamics and theoretical calculation are presented. In addition, challenges, perspectives, and development tendencies in this field are also discussed.

Composition design of Ti–Cr–Mn–Fe alloys for hybrid high-pressure metal hydride tanks

(Ti0.85Zr0.15)1.1Cr1−xMnFex (x=0, 0.05, 0.075, 0.1, 0.15) alloys with a C14-type Laves structure have been investigated for potential application in hybrid high-pressure metal hydride tanks used for fuel cell vehicles. The effects of the partial substitution of Cr with Fe on the hydrogen storage properties of (Ti0.85Zr0.15)1.1CrMn have been systematically investigated. Results show that the desorption plateau pressure increases with increasing the Fe content in (Ti0.85Zr0.15)1.1Cr1−xMnFex alloys, whereas the hydrogen capacity decreases. Among these alloys, (Ti0.85Zr0.15)1.1Cr0.925MnFe0.075 has the best overall properties, with a hydrogen desorption pressure of 10.6atm and a reversible capacity of 1.54wt% at 0°C under the pressure range between 0.1atm and 120atm.

Advanced high-pressure metal hydride fabricated via Ti–Cr–Mn alloys for hybrid tank

Ti–Cr–Mn-based alloys with a C14-type Laves structure have been investigated for potential application in hybrid high-pressure metal hydride tanks for fuel cell vehicles. The effects of partial substitution of Ti by Zr, and of Cr by Mo and W, on the hydrogen storage properties of Ti–Cr–Mn-based alloys have been systematically investigated. Among these alloys, (Ti0.85Zr0.15)1.1Cr0.9Mo0.1Mn shows the best overall properties, with a hydrogen desorption pressure and capacity of 9.54 atm and 1.78 wt% at 0 °C. The kinetics and cycling stability are also discussed for on-board hybrid high-pressure metal hydride tank applications. According to calculations, the volumetric H2 density of the hybrid system can reach the Department of Energy (DOE) 2017 target, while its gravimetric density remains at a high value of 2.72 wt% when 28% of the inner volume in a hybrid hydrogen metal hydride tank is filled with this alloy.

TiCrVMo alloys with high dissociation pressure for high-pressure MH tank

High-pressure metal hydride (MH) tank is a possible hydrogen storage system for fuel cell vehicles. The merit of the high-pressure MH tank system is improved by the use of a metal hydride with high dissociation pressure. In this study, TiCrV and TiCrVMo alloys with BCC structure has been developed for the high-pressure MH tank system. The developed TiCrVMo alloy shows 2.4 mass% of effective hydrogen capacity between 0.1 MPa and 33 MPa at 298 K, which has a dissociation pressure of 2.3 MPa at 298 K. By investigating the dissociation pressures of the synthesized metal hydrides, it is found that Mo has a special effect to increase dissociation pressure of the metal hydrides. This effect is probably attributed to the large bulk modulus of Mo compared to other elements.

Development of High-pressure Metal Hydride Tank for Fuel Cell Vehicles with Ti-Cr-V-Mo BCC Alloy

High pressure metal hydride tank system is a key technology for hydrogen powered fuel cell vehicles to get practical driving range. Both high storage capacity and good charge-discharge performance can be achieved by this system, however, mass reduction of the hydrogen-absorbing alloy is necessary. Ti25Cr50V20Mo5 alloy with BCC single phase structure, has been developed for this system and it shows 2.5 mass% of effective hydrogen capacity, 40% larger capacity than previous Ti35Cr34Mn31 system. It also shows high dissociation pressure and can release hydrogen from 233 K. Estimated hydrogen storage capacity by this alloy is 9.5 kg in 180 L tank. It enables over 900 km driving range of fuel cell vehicles. Hydrogen storage density in weight is 2.0 mass% and volumetric storage density is 5.3 kg hydrogen per 100 L as on-board tank system. Although higher storage capacity has obtained, this system gives that 72% of hydrogen can be stored within 5 minutes. This rapid charging capability is due to its small absolute value of ΔH, -25kJ/molH2. And further improvement in rapid charging is indicated by a simulation if the hysteresis of equilibrium pressure between absorbing and desorbing could be reduced.

High-pressure Metal Hydride Tank for Fuel Cell Vehicles

AbstractA new type of hydrogen-absorbing alloy tank has been developed. The high-pressure metal hydride (MH) tank has been designed based on a 35 MPa cylinder vessel. The heat exchanger module is integrated into the tank. Its advantage over high-pressure cylinder vessels is its large hydrogen storage capacity, for example 7.3 kg with a tank volume of 180 L. Cruising range is about 2.5 times longer than that of a 35 MPa cylinder vessel system with the same volume.The hydrogen-charging rate of this system is equal to the 35 MPa cylinders without any external cooling facility. Furthermore, release of hydrogen at 243 K is enabled due to the use of a hydrogen-absorbing alloy with a high disassociation pressure, Ti-Cr-Mn alloy with AB2 laves phase. It is thought that the high-pressure MH system is one realistic option for fuel cell vehicles to achieve a cruising range of over 700 km.