The usable capacity of porous materials for hydrogen storage

Maurice Schlichtenmayer,Michael Hirscher

doi:10.1007/s00339-016-9864-6

Maurice Schlichtenmayer, Michael Hirscher

Open Access

https://doi.org/10.1007/s00339-016-9864-6

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Journal: Applied physics	Publication Date: Mar 14, 2016
Citations: 47	License type: CC BY 4.0

Affiliation: Max Planck Institute for Intelligent Systems

Abstract

A large number of different porous materials has been investigated for their hydrogen uptake over a wide pressure range and at different temperature. From the absolute adsorption isotherms, the enthalpy of adsorption is evaluated for a wide range of surface coverage. The usable capacity, defined as the amount of hydrogen released between a maximum tank pressure and a minimum back pressure for a fuel cell, is analyzed for isothermal operation. The usable capacity as a function of temperature shows a maximum which defines the optimum operating temperature. This optimum operating temperature is higher for materials possessing a higher enthalpy of adsorption. However, the fraction of the hydrogen stored overall that can be released at the optimum operating temperature is higher for materials with a lower enthalpy of adsorption than for the ones with higher enthalpy.

Highlights

In 2014 Hyundai started leasing the first fuel cell vehicle to customers followed in 2015 by the Mirai from Toyota
For a further comparison of the different materials, we introduce the usable fraction in percent, which is defined as the usable capacity at the optimum operating temperature normalized by the overall absolute uptake at 2.5 MPa and 77 K
The usable capacity, i.e., the amount of hydrogen that can be released at a certain operating temperature between the maximum tank pressure and the back pressure required for the fuel cell, is the key value for technical application in a fuel cell vehicle

Summary

Introduction

In 2014 Hyundai started leasing the first fuel cell vehicle to customers followed in 2015 by the Mirai from Toyota. Hydrogen molecules can interact with solids by the socalled Van der Waals interaction establishing a weak bond between the hydrogen and the solid surface. This binding is 379 Page 2 of 11. Materials can be optimized for the storage of hydrogen by selecting structures with an ideal enthalpy of adsorption and by offering more surface for the adsorption of hydrogen. The materials with the highest hydrogen uptakes are so-called metal–organic frameworks (MOFs), which are highly porous structures with specific surface areas up to 6200 m2/g and micropore volumes up to 3.6 cm3/g [1, 2]

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Discussion

Conclusion