LiPo Battery Formation-Aging Process
LiPo batteries generally use aluminum-plastic film to encapsulate the core structure. The production method of the lipo battery in the prior art is: first batching ingredients, then making a winding core, and then performing encapsulation, baking, liquid injection, pre-sealing, formation, two-sealing, and volume separation steps in order to make a rechargeable lipo battery. In this page, we will mainly talk about the formation of the lipo battery.
The production and manufacture of lipo batteries are closely linked with each process step. In general, the production of lipo batteries includes the pole piece manufacturing process, the battery assembly process, and the final liquid injection, sealing molding, and aging processes. In the three-stage process, each function can be divided into several basic methods, and each step can significantly affect the final performance of the lipo battery.
Purpose of LiPo Battery Formation
The lipo battery pre-formation is to charge and discharge the manufactured lipo cells with a slight current. After the mass production of lipo cells, it is required to charge and discharge the battery. Regarding the purpose of pre-charging, there are two main points:
1) After the rechargeable lipo battery is made, the applicability is better. The physical properties are not suitable, or the correction phase is required (such as metal oxide negative electrodes with some alloy mechanisms); activation is required for the first charge and discharge.
2) During the first charge of a lipo battery, Li+ is released from the positive active material. After passing through the electrolyte-diaphragm-electrolyte, it is embedded in the negative electrode graphite material layer. During this process, electrons migrate from positive to negative poles along peripheral circuits. Due to the low potential of lithium ions embedded in the graphite negative electrode, the electrons will first react with the electrolyte to form an SEI film and some gases.
During this process, some gas will be generated and a small amount of electrolyte will be consumed. Some manufacturers will perform battery exhaust and liquid replacement operations after this process. Thickness exceeds 10%. For the graphite anode, the amount of gas generated is less, and the exhaust function is not needed, because the oriented SEI film hinders the further reaction of electrons and electrolytes during the first charging process, and the gas is no longer generated. This is the source of the irreversible capacity of graphite-based batteries. While causing irreversible capacity loss, it also stabilizes the battery.
Purpose of LiPo Battery Aging
Aging generally refers to the placement of the lipo battery after the first charge and the formation after the liquid injection is completed. It can be aged at room temperature or elevated temperature. Both of these functions make the properties and composition of the SEI film formed after initial charging and formation more stable. Stability of battery electrochemical performance. There are three main purposes of aging:
1) After the battery performance is good, a certain amount of SEI film will be formed on the graphite negative electrode inside the lipo battery, but the film structure is tight and the pores are small. Aging lipo batteries at high temperatures will help the SEI structure to reorganize and form a loose and porous film.
2) After the lipo battery is formed, the voltage is unstable, and its voltage is slightly higher than the actual voltage. The purpose of aging is to make its voltage more accurate and stable.
3) Put the lipo battery at a high temperature or medium temperature for a period of time to ensure that the electrolyte fully penetrates into the pole piece, which is conducive to the stability of battery performance.
The lipo battery formation-aging process is essential. In actual production, the battery charging and discharging process is selected according to the lithium battery material system and structural system. Nevertheless, battery formation must be charged and discharged under low current conditions. After these two basic processes, the stabilized battery is divided into capacities, and after packaging and other methods, it can be shipped.
If you want to know more about the rechargeable lipo battery manufacturing process, you can watch the below video.