Composite lithium supplement additive and lithium ion battery positive electrode lithium supplement method

The invention discloses a composite lithium supplement additive and a lithium ion battery positive electrode lithium supplement method. The composite lithium supplement additive is composed of an inner core lithium supplement compound and an outer layer phosphorus-containing compound. The lithium supplementing compound is selected from one or more of Li5FeO4, Li5Fe5O8, Li6CoO4, Li2NiO2, Li2O and Li2O2, and the phosphorus-containing compound is selected from one or more of phosphate ester, phosphite ester, alkyl phosphonate and phenyl substituted, halogen substituted and thiophenyl substituted compounds thereof. The lithium supplementing method comprises the following steps: mixing a positive electrode active material, a binder and the composite lithium supplementing additive in a solvent to prepare slurry; and uniformly coating the surface of a current collector with the slurry, and drying to prepare the lithium-supplementing positive electrode material. According to the lithium supplementing method, oxygen g