The project set out to create advanced metal‑hydride storage modules that combine high hydrogen‑storage capacity with superior thermal conductivity and mechanical robustness. The core of the effort was the development of graphite/metal‑hydride composite materials in which natural, high‑purity graphite serves as the heat‑conduction network while magnesium‑ and titanium‑containing hydride powders provide the hydrogen storage. Natural graphite grades with thermal conductivities above 300 W m⁻¹ K⁻¹ were selected, and the resulting composites exhibited overall conductivities ranging from 100 to 485 W m⁻¹ K⁻¹, with the best samples approaching 13 W m⁻¹ K⁻¹. This improvement in heat transfer is critical for rapid hydrogenation and dehydrogenation cycles in practical storage tanks.
To achieve a homogeneous distribution of the graphite and hydride particles, the team investigated several binders and dispersing aids. Four additives were screened: an acrylic resin dispersion, distilled water, a styrene‑butadiene‑rubber (SBR) dispersion, and a water‑based graphite dispersion. The SBR system yielded the highest bending strengths in 3‑point tests on 10 × 10 × 50 mm specimens, while all additives preserved the hydrogenation capacity of the composites. Scanning electron microscopy and energy‑dispersive X‑ray spectroscopy (EDX) mapping confirmed that oxygen was present throughout the material but did not accumulate at the graphite‑hydride interface, indicating that the additives did not form detrimental reaction layers.
A key scientific milestone was the first real‑time, in‑operando imaging of gas and heat transfer during hydrogenation and dehydrogenation of the composites. This enabled the team to observe morphological and structural changes as they occurred, providing unprecedented insight into the microscopic processes that govern performance. The data were used to refine the composite design and to develop a stacking sequence of graphite foil and metal‑hydride pellets that proved most effective. Two demonstrator storage units built with this configuration were successfully operated, demonstrating the modules’ dimensional stability and resistance to aging under repeated cycling.
The project was carried out by a consortium of two major German industrial partners, with SGL Carbon GmbH leading the development of the graphite composites and the provision of materials for system integration. The Federal Ministry of Economics and Energy (BMWi) funded the effort under grant number 03ET6119C. The research period ran from 1 July 2017 to 30 June 2021, and the final report covers the same timeframe. The consortium’s objectives included not only material development but also the creation of a technology‑transfer plan that is now being actively pursued and applied in industrial settings. The outcomes of the project—enhanced thermal conductivity, maintained hydrogenation capacity, improved mechanical strength, and proven system stability—represent a significant step toward commercially viable hydrogen storage solutions for stationary and mobile applications.