What steps are needed for lithium battery production？
The first step of electrode production: homogenization. The homogenization of lithium batteries is a key link in battery production. The homogenization is mainly to mix the active materials, binders and conductive agents into a uniform suspension.
After the dispersion of the slurry is completed, the next step is the coating and drying of the lithium battery. The spraying equipment squeezes the slurry from the nozzle and transfers it to the current collector to complete the coating. The spraying equipment can use viscosity and solid content. The higher the slurry, the better the electrode surface state, so it has been widely used. After coating, it is dried.
The electrode that has just been coated and dried will then be rolled by a roller press, which can increase the specific energy of the battery and significantly improve the conductivity and adhesion of the electrode. Then the electrode is divided into a certain width as needed, and then the electrode will be dried in a vacuum oven to remove the moisture in the electrode and minimize the impact of moisture on the life of the lithium battery and side reactions.
Now comes the next step in the production of lithium-ion batteries-the production of single cells. In order to prevent the electrodes from absorbing moisture again, the entire cell production process needs to be carried out in a dry room, and the environmental dew point is generally controlled at -40°C to -60°C. A good battery cell must first be welded to the tabs. The tab welding method is mainly ultrasonic welding. After the welding is completed, it is usually necessary to conduct a leak test and remove the batteries with unqualified leak rates. Common leak detection methods Including methods such as direct pressure, double pressure and differential pressure, good airtightness is the key to ensuring long-term stable and reliable performance of lithium-ion batteries. Therefore, battery leakage detection is also an essential part of the production of square power batteries.
The battery that has been screened for leak detection then goes to the very important injection process. Since the electrolyte of the lithium ion battery is very sensitive to moisture, the injection process must be carried out inside the drying room. In order to improve the infiltration effect of the electrolyte, it is usually necessary Vacuum liquid injection, that is, first exhaust the air inside the battery, then inject the electrolyte, and repeat it several times to make the electrolyte fully infiltrate the cell, then seal it, and place the battery in a high temperature environment to promote Infiltration of electrolyte.
The battery fully infiltrated by the electrolyte then enters the chemical conversion process, which is mainly activated by charging and discharging the battery with a small current.
The formed battery also needs to be aged. The so-called aging is to put a fully charged battery at a certain temperature. During the storage process, some side reactions inside the lithium-ion battery will cause the battery's external voltage and internal resistance to change. , By monitoring the voltage, internal resistance and capacity of the battery pack, it can eliminate those batteries with unqualified self-discharge and unqualified internal resistance to improve the consistency of the single battery, and the aging result is also the follow-up battery pack An important reference basis for matching. In order to accelerate battery aging and improve production efficiency, manufacturers usually perform aging at high temperatures (50-60°C) to shorten battery aging time. Finally, the battery is ready