Pre-charge formation method for lithium-ion battery

The invention discloses a pre-charge formation method for a lithium-ion battery. The pre-charge formation method for the lithium-ion battery comprises the following steps: (1) taking out a lithium-ion battery subjected to injection, standing and aging; in a first formation process, charging the lithium-ion battery to be 4-10% of charge state by using constant pre-charging current of 0.01-0.04 C; performing a first air exhaust; (2) in a second formation process, charging the lithium-ion battery to be 40-60% of charge state by using two-stage constant current; performing a second air exhaust to obtain the lithium-ion battery. According to the pre-charge formation method for the lithium-ion battery, two-time pre-charge and two-time exhaust pre-treatment are performed, so that waste gas generated by the chemical reduction reaction inside a battery during a pre-charge formation process is timely exhausted to the maximum extent. The pre-charge formation method has the advantages that the battery expansion ratio is reduced, the product quality is greatly improved, and the service life of the battery is prolonged; the process is simple, the production efficiency is high, the problems of battery expansion, battery off-size, low capacity and short circulation service life are effectively solved, and the pre-charge formation method is suitable for large-scale industrial production.