The invention relates to a
manufacturing technology of a
lithium ion battery and in particular relates to a liquid filling method of the
lithium ion battery. The method comprises the following steps: 1, filling a
lithium ion secondary battery to be filled with liquid with an electrolytic solution A containing
vinylene carbonate for the first time, wherein the liquid filling quantity is 30%-45% by
mass of the total liquid filling quantity; 2, forming; 3, filling the lithium ion secondary battery with an electrolytic solution B containing
vinylene carbonate for the second time, wherein the liquid filling quantity is 25%-35% by
mass of the total liquid filling quantity; 4, forming; 5, filling the lithium ion secondary battery with an electrolytic solution C containing
vinylene carbonate for the third time, wherein the liquid filling quantity is 15%-25% by
mass of the total liquid filling quantity; 6, forming; 7, filling the lithium ion secondary battery with an electrolytic solution D for the fourth time, wherein the liquid filling quantity is 10%-20% by mass of the total liquid filling quantity; 8,
ageing and performing secondary encapsulation to obtain the
lithium ion battery. According to the liquid filling method, the battery is promoted to form a stable and dense SEI (
solid electrolyte interface) film, the charging frequency of the battery can be effectively increased, and the service life of the battery can be effectively prolonged.