Briefly introduce the analysis and solutions of common problems of lithium-ion batteries

　　With the rapid development of science and technology, the scope and role of lithium batteries have long been self-evident. However, in our daily lives, lithium battery accidents occur from time to time and have always troubled us. In view of this, lithium battery custom manufacturer Guanli Da Battery has specially arranged the cause analysis and solutions to common problems of lithium ions, hoping to provide convenience to everyone. First of all, the voltage is inconsistent, and individual voltages are 1 lower. The low-voltage core caused by high self-discharge has large self-discharge, making the voltage drop faster than others. The voltage drop can be eliminated by storing the post-detection voltage. 2. Low voltage caused by uneven charging When the battery is charged after testing, the charge of the core is uneven due to the contact resistance of the testing cabinet or the inconsistency of the charging current. There is a small difference in the measured voltage during short-term storage (12 hours), but a large difference in voltage during long-term storage. There is no quality problem with this low voltage and can be solved by charging. After charging in production, store for more than 24 hours to measure voltage. 2. Lithium battery expansion 1. Lithium battery will expand when charging. When lithium battery is charged, lithium battery will naturally expand, but generally not more than 0.1 mm. However, overcharging will cause the electrolyte to decompose, increase the internal pressure, and lithium battery to expand. 2. Expansion during processing Generally speaking, abnormal processing (such as short circuit, overheating, etc.) will cause the internally heated electrolyte to decompose and the lithium battery to expand. 3. The thickness of the expanded battery increases with the number of cycles during cycling, but does not increase after more than 50 weeks. When 0.3≤0.6mm, the normal growth of the aluminum shell is more serious, which is caused by normal battery reaction. However, if the thickness of the shell is increased or the internal material is reduced, the expansion phenomenon can be appropriately reduced. 3. The internal resistance is too large1. If the detection accuracy of the test equipment is not enough or the contact power group cannot be eliminated, the internal resistance of the display is too large. The internal resistance tester should be tested using the AC bridge method principle. Excessive storage of lithium batteries for too long will lead to excessive capacity loss, internal passivation and changes in internal resistance, which can be solved through charge and discharge activation. 2. Internal resistance caused by abnormal heat Abnormal heating of the battery is caused by the processing of the iron core (spot welding, ultrasonic waves, etc.), which causes the diaphragm to thermally close and increase the internal resistance. 4. Battery explosion The situations where battery explosion usually occurs are as follows: 1. Overcharge explosion: If the protection circuit is out of control or the detection cabinet is out of control, the charging voltage is greater than 5V, causing the electrolyte to decompose, the internal reaction of the battery to be violent, the internal pressure of the battery to rise rapidly, and the battery to explode. 2. The overcurrent explosion protection circuit or detection cabinet is out of control, and the charging current is too large, causing lithium ions to be embedded, and metallic lithium is formed on the electrode surface, penetrating the separator, and the positive and negative electrodes are directly short-circuited, causing an explosion (rarely). 3. Explosion during ultrasonic welding of plastic casing When the plastic casing is ultrasonic welded, the ultrasonic energy is transferred to the battery core due to equipment reasons. Ultrasonic energy melts the internal separator of the battery and directly short-circuits the positive and negative electrodes, causing an explosion. 4. Explosion during spot welding During the spot welding process, excessive current can cause an explosion due to an internal short circuit. In addition, during the spot welding process, the positive connecting plate is directly connected to the negative electrode, causing the positive and negative electrodes to explode after a direct short circuit. 5. Over-discharge explosion Battery over-discharge or over-current discharge (above 3C) often causes the negative copper foil to dissolve and deposit on the separator, causing the positive and negative electrodes to directly short-circuit and cause an explosion (rarely occurs). 5. The main research results caused by improper processing are as follows: (1) Due to the forced movement of the spot welding positive connector, the positive contact of the iron core is poor, which increases the internal resistance of the iron core. (2) The spot welding joint is not firm and the contact resistance is large, which increases the internal resistance of the battery. In short, when choosing lithium battery products, you must choose a professional lithium battery manufacturer to produce high-quality, high-quality lithium battery products to effectively avoid problems.

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