Lithium ion battery, preparation method thereof, positive pole piece and power utilization device

The invention provides a lithium ion battery and a preparation method thereof, a positive pole piece and a power utilization device. The lithium ion battery comprises a positive pole piece, the positive pole piece comprises a positive current collector, a bottom coating arranged on at least one surface of the positive current collector and a positive active layer arranged on the surface, away from the positive current collector, of the bottom coating, and the bottom coating comprises lithium iron phosphate, a first binder and a conductive agent, the positive electrode active layer comprises a first binder, the positive electrode active layer comprises a second binder, at least one of the first binder and the second binder comprises hydrogenated nitrile rubber, the mass percentage of the second binder relative to the mass of the first binder is P, and P is greater than 0 and less than or equal to 99%. The lithium ion battery is good in heat resistance, still has good adhesion between pole piece materials under a high-temperature condition, and further has good high-temperature cycle performance.