Formation method of lithium ion battery

Abstract

A formation method of a lithium ion battery comprises the following steps of placing a battery cell of which aging is finished in a device for high-temperature pressurized formation, wherein the charging cutoff voltage is 3.5-3.8V; cooling the battery cell under a room temperature and a fixed pressure to make the temperature of the battery cell reduced to a room temperature; placing the cooled battery cell in a vacuum environment, puncturing an air bag of the battery cell, pumping air, and sealing; placing the battery cell of which air pumping is finished in a formation device for high-temperature pressurized formation, wherein the charging cutoff voltage is 3.9-4.5V; and cooling the battery cell under a room temperature and a fixed pressure to make the temperature of the battery cell reduced to the room temperature, and finishing formation. According to the formation method, the steps of puncturing the air bag and pumping air are added during hot-press formation, reaction gas can be timely eliminated, and thus, the internal resistance of the battery cell is effectively reduced; and with the two steps of high-pressure room-temperature cooling, the hardness of the lithium battery can be improved, the flatness of the battery cell is improved, and the performance of the lithium battery is improved.

Description

technical field [0001] The invention belongs to the technical field of manufacturing lithium ion batteries, and in particular relates to a formation method of lithium ion batteries. Background technique [0002] Lithium-ion batteries must go through a formation process during the production process. Through the formation process, the positive and negative electrode materials are activated to form an SEI film that is critical to the performance of lithium batteries, thereby improving the electrochemical performance of the battery. There are two main formation methods at present: one is to conduct formation at room temperature with a small current, which can fully guarantee the performance of lithium batteries, but the formation time is relatively long, and the relatively short time takes more than ten hours. , some even for a few days, seriously delaying the production schedule, low production efficiency, resulting in high production costs: the other is high-temperature and h...

AI Technical Summary

Problems solved by technology

If these gases cannot be removed in time and enter the interior of the cell, it will increase the internal resistance of the cell, hinder the electrode reaction, and affect the performance of the battery.

Images