New Method of Postmodifying the Particle Size and Morphology of LiFePO4 via Supercritical Carbon Dioxide

Abstract

Supercritical carbon dioxide (scCO2) was applied for the first time to post-treat two hydrothermally synthesized LiFePO4 of H1 and H2 to entirely alter their particle size and morphology. H1 had the morphology of platelets aggregated in one direction in size of about 20–30 μm, together with impurity of Fe2PO5. After the scCO2 treatment, the impurity phase was removed, and the aggregated platelets were broken into separate rhombus plates in size of about 3–5 μm, along with the formation of flowerlike balls of about 10–20 μm. On the other hand, H2 had the main morphology of platelets agglomerated in random directions in size of about 5 μm and covered by materials of glassy state. After the scCO2 measurement, the morphology was greatly changed and cubic particles of 1 and 2 μm were formed, together with the better-shaped and separately distributed platelets of 1 and 2 μm. Therefore, by optimizing the experimental parameters in both the hydrothermal synthesis and supercritical carbon dioxide processing, it is...