Improving hydrogen storage kinetics of polymeric composites via additions of La0.6Ce0.4Ni5 and carbon particles

Nanostructured metal hydrides have garnered interest in their potential to store hydrogen safely and effectively as an energy carrier. By partially substituting lanthanum (La) with cerium (Ce), the structure of lanthanum pentanickel (LaNi5) was maintained to create a novel encapsulated La–Ce–Ni-based metal hydride (La0.6Ce0.4Ni5). The incorporation of metal-polymer composites can protect metal hydrides from oxidation and enhance cyclic stability. Carbon-based materials such as graphene and multi-walled carbon nanotubes (MWCNTs) not only store hydrogen but also improve the reaction kinetics and address thermal management issues. This study presents La0.6Ce0.4Ni5 composites using porous polymers—polymethyl methacrylate (PMMA) and polyvinylidene fluoride (PVDF) and carbon-based materials (graphene, MWCNTs) synthesized via a solvent-based method. The aim is to enhance hydrogen storage kinetics and stability. The composite’s thermal stability was analyzed using differential scanning calorimetry, and its structural phase composition was examined through X-ray diffraction. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed to qualitatively estimate the surface functional groups. Hydrogen storage kinetics were measured using temperature-programmed desorption in a Sieverts-type apparatus. The creation of surface functional groups on La0.6Ce0.4Ni5 improved the dispersion of the polymer and carbon particles. Hydrogen storage kinetics were evaluated through dehydrogenation (DHH) experiments in a Sieverts-type apparatus. The composite, consisting of La0.6Ce0.4Ni5 with 8% PMMA and 8% MWCNTs can store 0.8 wt% H2 at room temperature and pressure in under 20 min with good stability over three cycles, while the hydrogenation (HH) at 5 bar pressure can store 1.05 wt% of hydrogen in less than three minutes. La0.6Ce0.4Ni5 is highly promising material for hydrogen storage due to its reversible hydrogen absorption and desorption capabilities, along with its high volumetric hydrogen density compared to many other options. These properties make it an ideal candidate for various applications such as fuel cell vehicles, portable power systems, thermal storage, and hydrogen compression.