Chemical synthetic method of lithium ion battery

A chemical synthetic method of a lithium ion battery comprises the following step: charging with constant current to 20%-60% of reversible capacity of the lithium ion battery; allowing standing for 4-25 h; charging with constant current and constant voltage to cut-off voltage of the lithium ion battery reaching 3.8-4.1 volt and cut-off current of the lithium ion battery reaching 0.01 C. The above chemical synthetic method of the lithium ion battery can effectively improve cycle performance of the lithium ion battery with high energy density.