Lithium-rich lithium ion battery diaphragm

The invention relates to a lithium-rich lithium ion battery diaphragm, which can provide a stable lithium ion source for a battery in the use process by arranging a lithium-rich coating at at least one side of the diaphragm, wherein lithium salt is contained in the lithium-rich coating. In the first charging and discharging process, lithium salt in a lithium-rich layer is dissolved in an electrolyte to release lithium ions, so as to supplement for the consumption of the lithium ions during formation of an SEI film. Meanwhile, the SEI film on the surface of a graphite negative electrode can berapidly formed and reaches a stable state, thereby reducing the quality of the SEI film, and reducing the impedance of the SEI film; in the using process of the lithium ion battery, lithium salt in the lithium-rich layer is gradually released, the concentration of the lithium salt in the electrolyte is kept, and the cycle life of the battery is prolonged; the lithium exists in a lithium compound mode, potential safety haz