Fundamentals and recent advances in polymer composites with hydride-forming metals for hydrogen storage applications

Hydrogen has unique properties that make it a promising energy vector to replace fossil fuels. However, it is still required to develop safe and efficient storage methods before being widely implemented. Storing hydrogen in hydride-forming metals (HFM) is an approach that has been extensively studied in the last decades. But only recently the preparation of polymer composites with HFM have been explored. Air resistance, volumetric stability and processability are some of the HFM properties that could be improved by incorporating a polymer phase. This review presents the fundamentals concepts of gas transport in dense polymers, and the evolution and trends of incorporating HFM particles into a polymer matrix. The most recent findings are summarized and discussed. The potential improvement of the most relevant classes of HFM and the mechanisms of how different classes of polymers could be advantageously used are reported.