Spray-dried composite microparticles of polyetherimide and LaNi5 as a versatile material for hydrogen storage applications

Abstract

Despite promising results for the encapsulation of sensitive components, spray drying hasn't been properly explored to produce energy storage powders. This study produced polyetherimide/LaNi5 (40/60 wt%) microparticles by spray drying for hydrogen storage and comprehensively characterize their morphological, thermal, and hydrogen sorption properties. First, the effects of spray drying parameters on microparticle size and morphology were evaluated by a 23 full factorial design. Samples were collected from the collector flask and the cyclone wall, differing particularly in the LaNi5 weight fraction. The microparticles had a wrinkled surface, but the polyetherimide matrix successfully encapsulated the LaNi5 particles. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that the glass transition temperature (Tg) and the onset of polyetherimide thermal degradation are inversely related to the LaNi5 fraction. The microparticles absorbed hydrogen without incubation time, reaching maximum capacity of 0.4 wt% and 0.3 wt% for the samples from the cyclone and the collector. The H2 capacity reduced after the first cycle. Spray drying effectively produced elastic microparticles where the polymer phase anchors the LaNi5 particles through the H2 absorption cycles, maintaining a constant morphology and thus an improved dimensional stability.