Lithium iron manganese phosphate precursor, lithium iron manganese phosphate positive electrode material and preparation method therefor, electrode material, electrode, and lithium-ion battery

A method for preparing a lithium iron manganese phosphate cathode material, comprising the following steps:

• (1) providing a lithium iron manganese phosphate precursor represented by Formula 1:
• (NH4) Mn1-x-yFexMyPO4·H2O/C,
• wherein 0.1<x≤0.6 and 0.01≤y≤0.04, and M is selected from Mg, Co, Ni, Cu, Zn, Ti, or a combination thereof;
• wherein the precursor has a secondary spherical particle structure formed of primary particles;
• an average particle size of the primary particles of the precursor is 10 nm to 500 nm;
• an average particle size of the secondary spherical particles is 1 μm to 50 μm;
• the precursor has a crystal structure of an orthorhombic system;
• (2) in presence of a solvent, mixing and homogenizing the lithium iron manganese phosphate precursor, a lithium source, a second carbon source, an M′ source and/or an N source to obtain a second slurry;
• and
• (3) removing the solvent in the second slurry to obtain a dry material, and calcining the dry material under protection of an inert atmosphere to obtain the lithium iron manganese phosphate cathode material,
• wherein the lithium iron manganese phosphate cathode material is reported by formula 2:
• LiiMn1-x-y-zFexMyM′z(PO4)1-nNn/C,
• wherein 0.1<x≤0.6, 0.01≤y≤0.04, 0≤z≤0.04, 0.9<i≤1.2 and 0≤n≤0.04, and z and n are not 0 at the same time;
• M is selected from Mg, Co, Ni, Cu, Zn, Ti, or a combination thereof;
• M′ is selected from Mg, Ca, Sr, Ti, V, Cr, Co, Ni, Cu, Zn, Zr, Y, Mo, Nb, B, Al, W, La, Sm, or a combination thereof;
• and
• N is selected from F, Cl, or a combination thereof, and
• wherein the lithium iron manganese phosphate cathode material has a secondary spherical particle structure formed of primary particles;
• an average particle size of the primary particles of the lithium iron manganese phosphate cathode material is 10 nm to 500 nm;
• a surface of the primary particles is uniformly coated with carbon;
• an average particle size of the secondary spherical particles is from 1 μm to 50 μm;
• a surface of secondary spherical particles is coated with carbon;
• and the lithium iron manganese phosphate cathode material has a crystal structure of an orthorhombic system.