How to find the cause of the failure of lithium-ion batteries

Take four battery samples for experiments. Through the experiments, we know that the voltage drop of the battery after the vibration test is 0V, which is lower than the standard specified value. The main reasons for temporary or permanent failure are as follows. Reasons for the temporary failure of the battery When the battery of sample 1 is charged and discharged in the state of communicating with the test system, it will receive data information at a certain frequency. The frequency used in the vibration experiment may interfere with the frequency of the battery receiving data information, causing data errors in the internal chipset, especially when the internal temperature of the BMU and the associated Table (table) are affected by abnormal temperature. Protection circuit action. Related reports have confirmed this. In the case that this temperature value has been abnormal, the charging and discharging function of the battery can be restored by repairing the relevant parameters. Sample 2 is because the battery's IC enters sleep mode during the vibration test, making the battery unable to output voltage normally. After that, by applying an appropriate external source to activate the IC, the battery can resume normal charging and discharging functions. Reasons for the permanent failure of the battery The failed batteries of sample 3 and sample 4 cannot restore their normal charge and discharge functions through data restoration or external activation, so they were disassembled and further studied. By disassembling the failed battery of sample 3, it was found that the battery was not firmly dispense or welded during the assembly process, which caused the internal components to loosen during the vibration or shock test, which interrupted the internal communication of the battery and could not normally output voltage. , Causing permanent damage to the battery. 4 Later, the company improved the process and re-sent samples for testing, and passed the test of UN38.3 for air transportation conditions of lithium-ion batteries. By disassembling the failed battery of sample 4, it is found that when the battery is subjected to relatively high frequency vibration, the anti-battery interference pad material inside the battery will be dispersed and moved, and its conductivity will be significantly reduced, resulting in relatively large static electricity, which makes the battery fuse Fuse causes the battery to fail to output voltage normally. 5Because the antistatic effect of conductive particles depends on the shape and surface structure of the particles, the irregular and rough surface particles have strong antistatic ability. If the particles can maintain good contact during the relatively high frequency vibration process , Mutual conduction plays an anti-static purpose. After disassembling the failed battery of sample 5, it was found that the solder of a blue signal wire inside the battery was broken. The manufacturer speculated that the battery did not use the wire storage tool during the production, which caused the wire root to be pulled and damaged. The wire broke in the impact test. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: 8 things to pay attention to in summer for electric vehicle batteries