Large-capacity lithium ion battery cathode and preparation method thereof

The invention belongs to the technical field of electrochemistry, and specifically relates to a cathode used in an all-solid-state film lithium ion battery, and a preparation method thereof. The cathode comprises a battery substrate, and a cathode film on the surface of the substrate. The cathode film on the surface of the substrate is a cobalt phosphate film. The preparation method comprises steps that: a, metal cobalt powder and amorphous phosphorus powder are mixed according to a molar ratio of 1:1-3; the materials are well mixed and grinded; and the mixture is pressed into a target used in pulsed laser deposition; b, the target and the substrate are placed in a vacuum deposition chamber, wherein a distance between the two is 25 to 50mm, a working gas is an argon atmosphere, and the temperature of the substrate is 500 to 700 DEG C; c, laser beams from a laser are focused through a lens and conducted onto the rotary target; and particles exited by the laser beams is sputtered onto the substrate. According to the invention, the cobalt phosphate film has good electrochemical property and good chemical stability. As a cathode film of a high-performance lithium ion battery, the film provides good charge/discharge circulation reversibility. The preparation method is simple and material saving.