Boron and Phosphorus Dual-Doped Carbon Coating Improves Electrochemical Performances of LiFe_0.8Mn_0.2PO₄ Cathode Materials

Although LiMPO4 (M = Fe, Mn) cathode materials have been widely applied in electric vehicles owing to the advantages of excellent safety, cycle stability, and low cost, poor electronic conductivity of LiMPO4 severely limits the further expansion of its applied field. Herein, the LiFe0.8Mn0.2PO4 composite with boron/phosphorus dual-doped carbon coating (LFMP@B/P–C) was fabricated by a sol–gel hydrothermal method. As a result, LFMP@B/P–C exhibits superior rate performance (97.1 mAh g–1 at 20 C) and preferable low-temperature performance (78.2 mAh g–1 at 1 C and −20 °C). It is mainly attributed to the synergistic effect of boron/phosphorus dual-doped carbon coatings, as confirmed by combined experimental characterizations with density functional theory calculations. That is, boron-doped carbon coating offers additional hole carriers, and phosphorus doping provides abundant electron carriers, making it easy for electrons to escape and enter and greatly improving the conductivity of the material. In addition, the phosphorus atom also acts as a bridge so that the carbon coating layer is tightly coated on the surface of the material. This will provide an idea for the research on the modification of cathode materials in the future.