Polymer lithium-ion battery core adopts aluminum-plastic composite film packaging technology. When the battery cell produces gas due to abnormal chemical reaction, the outer packaging will expand, and the battery cell will expand (slightly or seriously). No matter what the appearance, the battery cell's service performance will be seriously invalid, resulting in the battery cell being unusable. Here is a brief introduction to the causes of abnormal gas production in the process:

1, poor packaging: the reason for poor packaging on three sides of the battery, and poor packaging on either side will lead to batteries. Poor packaging causes moisture in the air to enter the battery cell, which decomposes the electrolyte to produce gas.

2. Surface damage: During the drawing process, the battery cell is damaged abnormally or artificially (such as pinholes), so that water enters the battery cell.

3. Angular loss: Due to the special deformation of aluminum in the corner, the shaking of the airbag will distort the angular position, resulting in the damage of al (the bigger the battery, the easier the airbag will be damaged) and the barrier effect on water will be lost. You can add wrinkle-removing glue or hot melt adhesive to the corners to relieve it. Moreover, it is forbidden to move the battery cells with airbags in each process after top sealing, and more attention should be paid to the operation mode to prevent the battery cells from swinging on the aging board.

4. The water content of the battery exceeds the standard: the water content of the battery has certain requirements. Once the water content exceeds the standard, the electrolyte will fail and generate gas after formation. The main reasons for the excessive water content of battery are: excessive water content of electrolyte, excessive water content of bare battery and excessive humidity of drying room. If it is suspected that excessive moisture causes flatulence, the process can be traced back.

5. Abnormal formation process: An error in formation process will lead to flatulence of the battery.

6. Unstable 6.SEI film: During the charging and discharging process of capacity test, the battery cell slightly flattens.

7. Overcharge and overdischarge: Due to the abnormality of process, machine or protective plate, the battery cell will be overcharged or overdischarged, and the battery cell will expand seriously.

8. Short circuit: Due to operational error, the two lugs of the charged battery contact and short circuit occurs, and the battery cell will expand.