Positive electrode active material, positive electrode slurry, positive electrode sheet and battery

A positive electrode slurry, comprising a positive electrode active material, a conductive agent, a binder and a solvent, wherein the positive electrode active material comprises lithium manganese iron phosphate and lithium-rich lithium ferrite;

• wherein, a mass ratio of the lithium-rich lithium ferrite in the positive electrode active material is 0.5%-5%;
• a particle size D50 of the lithium manganese iron phosphate is d1, a particle size D50 of the lithium-rich lithium ferrite is d2, and 0.05≤d1/d2≤0.32.

A positive electrode sheet, prepared by using a positive electrode active material or a positive electrode slurry, wherein the positive electrode active material comprises lithium manganese iron phosphate and lithium-rich lithium ferrite, wherein, a mass ratio of the lithium-rich lithium ferrite in the positive electrode active material is 0.5%-5%;

• a particle size D50 of the lithium manganese iron phosphate is d1, a particle size D50 of the lithium-rich lithium ferrite is d2, and 0.05≤d1/d2≤0.32, wherein the positive electrode slurry comprises the positive electrode active material, a conductive agent, a binder and a solvent.