▎ 摘　　要

NOVELTY - A nano-lithium iron manganese positive electrode composite material preparing method involves mixing iron source, manganese source, graphene oxide and additive and dispersing into water to form a solution-A. The solution-A is dispersed in phosphorus source and water to form a solution-B. The solution-A and solution-B are mixed, added with nitric acid solution to regulate pH value of the reaction system to 2.0-4.5, and the reaction system is transferred into a hydrothermal reaction vessel at 150-180 degrees C for 10-24 hours, filtered, washed and dried to obtain manganese iron phosphorus/graphene. The manganese iron phosphorus/graphene, lithium source and carbon source are mixed to obtain mixture, where the lithium source and manganese iron phosphorus/graphene molar ratio is 1-1.05:1, the manganese iron phosphorus/graphene and carbon source molar ratio is 3-10:1. The mixture is dried and sintered at 600-800 degrees C for 4-12 hours, cooled and sieved to obtain the finished product. USE - Method for preparing nano-lithium iron manganese positive electrode composite material. ADVANTAGE - The method enables preparing nano-lithium iron manganese positive electrode composite material with uniform appearance, better dispersibility, shortened diffusion distance of lithium ion migration and enhanced ionic conductivity. DETAILED DESCRIPTION - A nano-lithium iron manganese positive electrode composite material preparing method involves mixing iron source, manganese source, graphene oxide and additive and dispersing into water to form a solution-A. The solution-A is dispersed in phosphorus source and water to form a solution-B. The solution-A and solution-B are mixed, added with nitric acid solution to regulate pH value of the reaction system to 2.0-4.5, and the reaction system is transferred into a hydrothermal reaction vessel at 150-180 degrees C for 10-24 hours, filtered, washed, dried and collected to obtain manganese iron phosphorus/graphene (Mn1-xFexPO4)/graphene. The manganese iron phosphorus/graphene, lithium source and carbon source are mixed to obtain mixture, where the lithium source and manganese iron phosphorus/graphene molar ratio is 1-1.05:1, and the manganese iron phosphorus/graphene and carbon source molar ratio is 3-10:1. The mixture is dried at 60-80 degrees C, sintered at 600-800 degrees C for 4-12 hours, cooled after crushing and subjected to sieving treatment to obtain the finished product.