Boron-doped reduced graphene oxide coated lithium manganese iron phosphate composite material and preparation method thereof

The invention belongs to the field of synthesis and application of lithium ion battery positive electrode materials, and particularly provides a boron-doped reduced graphene oxide coated lithium manganese iron phosphate composite material and a preparation method thereof.The preparation method comprises the following steps that a lithium source, an iron source, a manganese source, a phosphorus source, a boron source, an organic carbon source and water are mixed and ground, graphene oxide is added, and drying is performed to obtain a lithium manganese iron phosphate composite material; and calcining in a nitrogen or inert gas atmosphere, and crushing to obtain the product. By compounding boron-doped reduced graphene oxide and lithium manganese iron phosphate, on one hand, the edge defects of the reduced graphene oxide can be increased by boron doping, and on the other hand, lithium manganese iron phosphate particles can form a two-dimensional conductive network from points to surfaces by fully utilizing the ch