Lithium-ion battery aging
Aging generally refers to the storage after the battery is first charged after assembly. It can be aging at room temperature or high temperature. All functions are to stabilize the performance and composition of the SEI film formed after the initial charge.
The standard aging temperature is 25℃, while the temperature for high-temperature aging varies among plants, ranging from 38℃ to 45℃. The aging time is between 48 and 72 hours.
There are two situations: aging and sealing at the opening.
For batteries with openings, keeping the relative humidity below 2% at room temperature will result in better sealing after aging.
Regarding high-temperature aging, sealed aging has a better effect.
However, it is certain that there are electrochemical dynamic changes during the aging process, which greatly contributes to the stability of the SEI and can promote the stability of the electrochemical system.
The purpose of aging
In practice, one reason is to ensure sufficient electrolyte wetting, and another is to allow certain active components of the cathode material to undergo certain deactivation reactions, thus stabilizing the overall battery performance. Many companies use high-temperature aging to accelerate this process. However, high-temperature aging requires careful control of time and temperature. Because high-temperature aging can exceed the degradation effects of normal aging temperatures on living materials, good control ensures the full reaction of effective components and stable battery performance. Poor control leads to decreased electrical performance, low yield, increased infrared radiation, and even leakage and other problems.
Batteries exhibit more stable performance after high-temperature aging. Most lithium-ion battery manufacturers employ high-temperature aging in their production processes. This involves aging the batteries at 45-50°C for 1-3 days. After high-temperature aging, potential defects in the batteries will be revealed, such as changes in voltage, thickness, and internal resistance. These are comprehensive indicators that directly test the safety and electrochemical performance of this batch of batteries.
Currently, most battery companies use domestically produced, low-quality separators for mass production, and high-temperature aging has become an unwritten rule for safety testing of the internal structure of batteries.
High-temperature aging is only to shorten the entire production cycle of the battery. Players only put the battery in the atmosphere at high temperatures to accelerate the chemical reaction. The battery may be damaged if the high temperature does not bring the benefits. It is best to incubate at room temperature for more than three weeks. We need to ensure that the separator, electrolyte balance and other chemical reactions are balanced, and then the battery performance will be more realistic.
