Improving electrochemical performance of LiCoPO4 via Mn substitution

We report a Mn substitution strategy to tailor the morphology, size, surface of LiCo1-xMnxPO4 (x=0.2, 0.5 and 0.8) materials using a facile organic acid mediated hydrothermal approach. The results show that the Mn substitution plays a profound role in reducing the particle size, stabilising the surface, and improving the diffusivity of LiCo1-xMnxPO4 materials, thus leading to much enhanced electrochemical performance compared with LiCoPO4. However, when excessive Mn (e.g. x=0.8) is present in the olivine crystal, the performance of LiCo1-xMnxPO4 degrades, possibly due to Jahn-Teller lattice distortion. As a result, the LiCo0.5Mn0.5PO4 displays the best electrochemical performance in terms of capacity delivery, cyclability and rate capability. Therefore, the Mn substitution in LiCoPO4 could be an efficient way to achieve high energy density and long cycle life for high voltage materials.