Improving electrochemical performance of LiCoPO4 via Mn substitution

Abstract

We report a Mn substitution strategy to tailor the morphology, size, surface of LiCo_1–xMn_xPO₄ (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 LiCo_1–xMn_xPO₄ 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 LiCo_1–xMn_xPO₄ degrades, possibly due to Jahn–Teller lattice distortion. As a result, the LiCo_0·5Mn_0·5PO₄ 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.