Positive pole piece, preparation method thereof and lithium ion battery

The invention relates to the technical field of electrode preparation, in particular to a positive pole piece, a preparation method thereof and a lithium ion battery. The positive pole piece comprises a current collector and an active substance layer arranged on the surface of the current collector, wherein the active substance layer comprises an inner surface in contact with the current collector and an outer surface far away from the current collector; the active substance layer comprises a lithiated porous material, and the mass content of the lithiated porous material is gradually reduced in the thickness direction from the outer surface to the inner surface. By increasing the number of freely moving lithium ions and reducing the diffusion distance of the lithium ions, the problems that the capacity of a thick electrode cannot be fully exerted, the high-rate discharge concentration polarization is large and the like are greatly solved. 本发明涉及电极制备技术领域，具体为一种正极极片及其制备方法和锂离子电池。该正极极片包括集流体和设置在所述集流体表面的活性物质层，所述活性物质