Withthe rapid development of the level of science and technology, the scopeand role of lithium batteries have long been self-evident, but in ourdaily life, lithium battery accidents are always emerging, alwaysplagued us. In view of this, Qianguo Electronics specially organized Lithium ion common problem causes analysis and solution measures, hope to provide convenience for everyone.
First, the voltage is inconsistent, individual low
1. Low self-discharge voltage
Theself-discharge of the battery core makes its voltage decrease fasterthan others, and the voltage can be eliminated by storing the post-checkvoltage.
2. Uneven charging causes low voltage
Afterthe battery is detected, when the battery is charged, the battery isnot uniformly charged due to the inconsistent contact resistance or thedetection cabinet charge current. Inthe short-term storage (12 hours) the voltage difference is very small,but the long-term storage voltage difference is large, this low voltageand no quality problems can be solved by charging. After storage in the production of stored voltage over 24 hours.
Second, the internal resistance is too large
1. Detecting device differences
Ifthe detection accuracy is not enough or the contact group cannot beeliminated, the internal resistance of the display will be too large.Therefore, the principle of AC bridge method should be used to test theinternal resistance instrument.
2. Store too long
Lithiumbatteries are stored for too long, resulting in excessive capacityloss, internal passivation, and increased internal resistance, which canbe solved by charging and discharging.
3. Abnormal heat caused by large internal resistance
Inthe processing (spot welding, ultrasonic, etc.) of the battery core,the battery is abnormally heated, so that the diaphragm generates athermal closing phenomenon, and the internal resistance is greatlyincreased.
Third, lithium battery expansion
1. Lithium battery expands when charging
Whenthe lithium battery is being charged, the lithium battery willnaturally expand, but generally it does not exceed 0.1 mm, but theovercharge will cause the electrolyte to decompose, the internalpressure increases, and the lithium battery expands.
2. Expansion during processing
Ingeneral, abnormal processing (such as short-circuit, overheating, etc.)occurs, and internal electrolyte is too hot to decompose and thelithium battery expands.
3. Expansion during cycling
Whenthe battery is circulated, the thickness will increase with the numberof cycles, but it will not increase after more than 50 weeks. Generally,the normal increase is 0.3~0.6 mm. The aluminum shell is more serious.This phenomenon is caused by the normal battery reaction. However,if you increase the thickness of the shell or reduce the internalmaterial, you can properly reduce the expansion phenomenon.
Fourth, the battery has lost power after spot welding
Thevoltage of the aluminum shell core after spot welding is lower than3.7V, generally because the spot welding current has roughly broken downthe internal diaphragm of the core, causing the voltage to drop tooquickly.
Normally,the spot welding position is incorrect, and the correct spot weldingspot should be spot welded on the bottom or marked with “A” or “—”. Nologo on the side or large side can not be spot welded. Inaddition, some spot welding nickel strips are poor in weldability, sothey must be used for spot welding of a large current, so that theinternal high-temperature tape cannot work, causing an internal shortcircuit in the battery core.
The battery power loss after spot welding is also partly due to the self-discharge of the battery itself.
V. Battery explosion
Battery explosion generally occurs in the following situations:
1. Overcharge explosion
Lossof control of the protection circuit or loss of control cabinetdetection causes the charging voltage to be greater than 5V, causingdecomposition of the electrolyte, violent reaction inside the battery,rapid increase in the internal pressure of the battery, and explosion ofthe battery.
2. Overflow explosion
Ifthe protection circuit is out of control or the control cabinet is outof control, the charging current is so large that lithium ions are toolate to embed, and lithium metal is formed on the surface of the polepiece, penetrating the diaphragm, and the positive and negative polesshort-circuit directly to cause explosion (infrequently).
3. Explosion when ultrasonic welding plastic shell
Ultrasonicwelding of plastic shell, due to equipment reasons to make ultrasonicenergy transfer to the battery core, ultrasonic energy is very large sothat the battery internal diaphragm melting, positive and negativedirect short circuit, resulting in an explosion.
4. Explosion when spot welding
Theexcessive current during spot welding causes serious internal shortcircuit explosion. In addition, the positive connection piece isdirectly connected to the negative electrode during spot welding, andthe positive and negative electrodes are directly short-circuited andthen exploded.
Batteryover-discharge or over-current discharge (3C or more) makes it easy forthe negative electrode copper foil to be dissolved and deposited on theseparator so that positive and negative electrodes can be directlyshort-circuited to cause explosion (infrequently).
6. Explosion when vibration falls
Whenthe battery is violently vibrated or dropped, the inner pole of thebattery is misaligned and directly short-circuited and exploded (rarelyoccurs).
Sixth, battery 3.6V platform is low
1. Inadequate sampling of the detection cabinet or instability of the detection cabinet results in a low test platform.
2. Low ambient temperature causes the platform to be low (discharge platform is greatly affected by ambient temperature)
VII. Inadequate processing
(1)Forcefully moving the spot welding anode connecting piece causes poorcontact of the positive electrode of the battery core, so that theinternal resistance of the battery core is large.
(2)The spot welding joints are not welded well, and the contact resistanceis large, so that the internal resistance of the battery is large.
Inshort, the choice of lithium battery products to choose professionallithium battery manufacturers, high-quality, high-quality lithiumbattery products, can effectively avoid the occurrence of problems. Thousands of fruit electronics, professional lithium battery products and service providers.