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Editor:ESTL Category:Technical information Release time:2019-08-15 Click volume:163
With the rapid development of science and technology, the scope and role of lithium batteries have long been self-evident, but in our daily life, the problem of lithium battery accidents is always endless, which is always plaguing us. In view of this, the ESTL Xiaobian special finishing Analysis of the causes of common problems with lithium ions and solutions.
1. The voltage is inconsistent and the individual is low
(1) The self-discharge causes a low voltage
The self-discharge of the battery core makes the voltage drop faster than others, and the low voltage can be eliminated by detecting the voltage after storage.
(2) Unbalanced charging causes low voltage
When the battery is tested, the charge of the battery is uneven due to the contact resistance or the inconsistent current of the test cabinet. In the short-term storage (12 hours), the voltage difference is small, but the voltage difference is large when stored for a long time. This low voltage has no quality problem and can be solved by charging. Store the voltage for 24 hours after charging in production.
2. Internal resistance is too large
(1) Differences in testing equipment
If the detection accuracy is not enough or the contact electric power group cannot be eliminated, the internal resistance of the display will be too large. The internal resistance instrument test should be tested by the principle of AC bridge method.
(2) Storage time is too long
Lithium batteries are stored too long, resulting in excessive capacity loss, internal passivation, and increased internal resistance, which can be solved by charge and discharge activation.
(3) The internal resistance is caused by abnormal heat
The battery is processed (spot welding, ultrasonic, etc.) to abnormally heat the battery, causing the diaphragm to thermally close and the internal resistance is seriously increased.
3. Lithium battery expansion
(1) Lithium battery expands when charging
When the lithium battery is being charged, the lithium battery naturally expands, but generally does not exceed 0.1 mm, but overcharging causes the electrolyte to decompose, the internal pressure increases, and the lithium battery expands.
(2) Expansion during processing
Generally, processing abnormalities (such as short circuit, overheating, etc.) occur, causing internal heat to be excessively decomposed by the electrolyte, and the lithium battery is expanded.
(3) Expansion during circulation
When the battery is circulating, 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, and the aluminum shell is more serious. This phenomenon is caused by normal battery reaction. However, if the thickness of the casing is increased or the internal material is reduced, the expansion phenomenon can be appropriately reduced.
4. The battery has a power failure after spot welding
The voltage of the aluminum shell after spot welding is lower than 3.7V. Generally, the spot welding current is too short to cause the internal diaphragm of the battery to break down, causing the voltage to drop too fast. Generally, the spot welding position is not correct. The correct spot welding position should be spot welded at the bottom or with the mark "A" or "-" side. The unmarked side and large face cannot be spot welded.
In addition, some spot welding nickel strips have poor solderability, so large current spot welding must be used, so that the internal high temperature resistant tape does not work, causing internal short circuit of the battery core. The battery power loss after spot welding is also partly due to the large self-discharge of the battery itself.
Label: Battery overhaul，Common battery failure
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