Improving the electrochemical activity of LiMnPO4 via Mn-site co-substitution with Fe and Mg

LiMnPO4, LiMn0.9Fe0.1PO4 and LiMn0.9Fe0.05Mg0.05PO4 were synthesized by a solid-state reaction route. All samples are single phase with a similar morphology, but the cation substitution results in a crystal lattice shrink because of the smaller ionic radii of Mg2+ and Fe2+. The Fe and Mg co-substitution leads to a significantly increased reversible capacity due to the enhanced electrochemical kinetics. The LiMn0.9Fe0.05Mg0.05PO4 sample exhibits a high capacity, a good cyclability and an excellent rate capability.