The nature and effects of the thermal stability of lithium hydroxide

Temperature programmed decomposition and complimentary microscopy/spectroscopy techniques were performed on lithium hydroxide with micron-sized grains. The lithium hydroxide grains thermally decomposed into Li2O, releasing H2O, following a three dimensional phase boundary moving from the surface inward. The energy barriers measured for the decomposition of surface and near-surface lithium hydroxide are noticeably smaller than those of bulk counterpart. The conversion of Li2O grains back to lithium hydroxide during moisture exposure was also found to proceed from the surface inward such that surface states are filled before bulk states. In a different set of experiments, nanometer-scale composite grains composed of LiD inner cores and LiOH outer layers were observed to form on top of pressed polycrystalline LiD upon moisture exposure. A diffusion coefficient on the order of 10−23 m2/s was measured for the diffusion controlled reaction of LiOH with LiD in the nanopowder at room temperature in a dry environment. The measured kinetics were used to model the evolution of the LiD/LiOH composite system in a dry environment.