Common Causes and Solutions of Lithium Ion (1)


With the rapid development of science and technology, t […]

With the rapid development of science and technology, the use range and role of lithium batteries have long been self-evident, but lithium battery accidents are constantly emerging in our daily lives, which constantly plagues us. In view of this, Xiaobian specially organized lithium Ion common cause analysis and solutions, I hope to provide convenience for everyone.
First, the voltage is inconsistent, and individual is too low
1. Large self-discharge results in low voltage: The large self-discharge of the battery cell causes its voltage to decrease faster than others. The low voltage can be eliminated by storing the post-detection voltage.
2. Uneven voltage caused by low voltage: When the battery is charged after the test, due to the contact resistance or the charging current of the detection cabinet is not consistent, the battery is not uniformly charged. The difference in voltage measured during short-term storage (12 hours) is small, but the voltage difference is large during long-term storage. This low voltage has no quality problem and can be solved by charging. Store the voltage for more than 24 hours after charging in production.
Second, the internal resistance is too large
1. Differences in detection equipment: if the detection accuracy is insufficient or the contact with the electrical group cannot be eliminated, the internal resistance of the display will be too large. The internal resistance instrument should be tested by the principle of AC bridge method.
2. The storage time is too long: the lithium battery is stored for too long, causing excessive capacity loss, internal passivation, and internal resistance becoming large, which can be solved by charging and discharging activation.
3. Large internal resistance caused by abnormal heating: the battery core is abnormally heated during processing (spot welding, ultrasonic, etc.), causing the diaphragm to thermally close, and the internal resistance is seriously increased.
Third, lithium battery expansion
1. Lithium battery swells during charging: When a lithium battery is charged, the lithium battery will naturally swell, but generally does not exceed 0.1mm, but overcharging will cause the electrolyte to decompose, the internal pressure will increase, and the lithium battery will expand.
2. Expansion during processing: Generally, processing abnormalities (such as short circuit, overheating, etc.) cause the internal electrolyte to decompose due to excessive heating, and the lithium battery swells.
3. Expansion during cycling: When the battery is cycling, the thickness will increase with the number of cycles, but it will not increase after more than 50 weeks. Generally, the normal increase is 0.3 ~ 0.6 mm. The aluminum case is more serious. This phenomenon is a normal battery. The reaction is caused. However, if the shell thickness is increased or the internal materials are reduced, the swelling phenomenon can be appropriately reduced.