What is the cause of flatulence in polymer lithium-ion batteries?

July 19, 2022

A slight swelling of the polymer lithium battery will affect the use, reduce the battery performance, and in severe cases will burst the packaging aluminum foil, causing leakage and corrosion. Next, let's analyze the reasons for the inflation of polymer lithium batteries.

What is the cause of flatulence in polymer lithium-ion batteries?

1. The cause of gas production

There are two types of gas production in flexible packaging lithium-ion batteries: normal gas production and abnormal gas production. Normal gas production refers to the chemical formation process in the battery cell production process, which is accompanied by the formation of the SEI film, and is often referred to as chemical production gas. This kind of gas can generally be temporarily stored in the air bag and discharged in the subsequent process, which does not have a significant impact on the cell.

Abnormal gas production means that when the air bag is removed and the packaging is completed, the amount of gas is excessive due to an abnormality inside the battery. In this case, the gas cannot be discharged, causing the battery core to swell, affecting the use of electrical appliances, and causing damage to the battery core. Performance deteriorates. When the internal pressure is too large, it is easy to open the packaging aluminum foil, causing serious damage such as liquid leakage and corrosion. Therefore, understanding the entire gas production process of the cell and preventing abnormal gas production is the key to the production of flexible packaging lithium-ion batteries.

2. What is the reason for the flatulence of the soft pack lithium battery?

There are two main reasons for the bulging of lithium batteries. One is the production problem of the manufacturer, the production environment is harsh, the production equipment is old, etc., so that the coating of the battery is uneven, and the electrolyte is mixed with dust particles. All of these may make the lithium battery pack bulge when the user uses it, or even more dangerous.

Another reason lies in the user itself. If the user uses the lithium battery product improperly, such as overcharging and overdischarging, or continuously using it in an extremely harsh environment, it may also cause the lithium battery to bulge.

The battery has not been used for a long time, and then it has not been well preserved. When it is not used when exposed to the air for a long time, and the battery is fully charged. Since the air is conductive to a certain extent, it is equivalent to the direct contact between the positive and negative electrodes of the battery if the battery is left for too long, resulting in a chronic short circuit.

The main reason for the bulge of the lithium battery is that a violent reaction similar to a short circuit occurs inside the battery, generating a lot of heat, which in turn causes the electrolyte to decompose and gasify, and the lithium battery will bulge.