Lithium battery aging

Aging generally refers to the placement of the battery after the first charging and formation after the battery is assembled and injected. It can be either normal temperature aging or high temperature aging. The function is to stabilize the properties and composition of the SEI film formed after the initial charging.
The normal temperature aging temperature is 25 degrees, and the high temperature aging varies from factory to factory. Some are 38 degrees and 45 degrees. The time is between 48-72 hours.
Aging is divided into two cases: opening and sealing:
For the battery formed by opening, if the relative humidity can be controlled below 2% for normal temperature aging, it is better to seal after aging.
For high temperature aging, aging after sealing is better.
However, it is certain that the aging process has electrochemical kinetic changes, which is of great help to the stability of the SEI and can promote the stability of the electrochemical system.
purpose of aging
In fact, the principle is similar. One reason is to fully infiltrate the electrolyte, and the other is that some active components in the positive and negative active materials are deactivated through a certain reaction, which makes the overall performance of the battery more stable. In order to make this process more stable Accelerate, adopt high temperature aging, but high temperature aging needs to pay attention to control time and temperature, because high temperature aging will have more deterioration effect on the active material than normal temperature aging, if the control is good, the active components are fully reacted, the battery characteristics are stable, and the control is not good. , over-reacting, then the electrical performance will decrease, the capacity will decrease, the IR will increase, and even leakage will occur.
The battery performance after high temperature aging is more stable. Most lithium-ion battery manufacturers adopt the high temperature aging operation method in the production process. The temperature is 45~50 degrees Celsius for 1~3 days, and then shelved at room temperature. After high temperature aging, the potential adverse phenomena of the battery will be exposed: such as voltage changes, thickness changes, and internal resistance changes, which are the comprehensive indicators that directly test the safety and electrochemical performance of this batch of batteries.
Today, most battery companies use inferior and low-end domestic diaphragms for mass production, and high temperature aging has also become an unspoken rule for the safety performance inspection of the internal structure of the battery.
High temperature aging is only to shorten the entire production cycle of the battery. The newly formed battery only accelerates the chemical reaction of the battery at high temperature, which does not have much benefit to the battery and may damage the battery. It is best to leave it at room temperature for more than three weeks. , so that the positive and negative electrodes, diaphragm, electrolyte, etc. can fully carry out chemical reactions to achieve a balance, and the battery performance is more realistic at this time.