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Lithium-ion analysis of frequently asked questions and solutions
Dec 09, 2016

Inconsistent, voltage, low

1. Self discharge caused by low

Batteries self-discharge, its voltage drops faster than the other, low voltage can be eliminated by storage after checking voltage.

2. Charging does not cause low

When charging after the battery test, due to contact resistance or to detect inconsistencies caused charged current battery charge balance. In a short time (12-hour) measuring voltage differences are small, but when long stored voltage difference, this low voltage and no quality problems, can be resolved through charges. Stored for more than 24 hours after the production charge voltage.

Second, the large internal resistance

1. Test equipment difference

If the precision is not or cannot eliminate the contact group, large internal resistance will result in a display, should adopt the principle of alternating current bridge method to test internal resistance testing.

2. Storage time is too long

Lithium-ion batteries stored too long, causes capacity loss is too large, passivation, internal resistance becomes large, can be solved by charge and discharge activation.

3. Caused by abnormal heat resistance

Cell processing (such as spot welding, ultrasonic) battery abnormal heating, thermal closed diaphragm, serious internal resistance increases.

Third, the lithium-ion battery expansion

1. When charging the lithium-ion battery expansion

When charging the lithium-ion battery, lithium-ion battery will naturally swell, but generally not more than 0.1mm, but charging will cause decomposition of the electrolyte, the pressure increases, lithium battery expansion.

2. When expansion

Is a processing exception (such as short circuit, overheating and other) causes internal heat decomposition of the electrolyte, lithium battery expansion.

3. Loop expansion

Battery cycle, increased thickness will increase as the number of cycles, but after more than 50 weeks did not increase, the normal increase in 0.3~0.6 mm, aluminum is more serious, this phenomenon is caused by normal cells. But if increased shell thickness or decrease of internal material may be appropriately reduced signs of expansion.

Battery power off after four, spot welding

Aluminium batteries after the welding voltage is lower than 3.7V, usually because the welding current is too large causing breakdown short circuit batteries internal diaphragm, causing voltage drop too fast.

General due to a spot position is not correct, correct welding position should be at the bottom, or marked "a" or "-" side welding, unmarked side and be able to spot. Some welding solderability of nickel is so bad, so you must use very high current welding, resulting in high temperature tape would fail, causing batteries short-circuited.

Spot after battery power loss is also partly attributable to large battery self-discharge.

Five, battery explosion

Exploding batteries generally have the following situations:

1. Charge explosion

Protection circuit is out of control or Cabinet out of control the charging voltage than 5V is detected and cause decomposition of the electrolyte, the battery reacts violently, rapid rise in pressure inside the battery, battery explosion.

2. Current explosion

Protection circuit out of control or testing cabinets out of control so that the charging current is too large causing lithium-ion embedded in time, which formed on the electrode surface for lithium metal, penetrates the membrane, anode and direct short causing an explosion (rare).

3. Ultrasonic welding of plastic explosive shell

Ultrasonic welding of plastic shell, due to reasons on the ultrasonic energy transferred to the cells, ultrasonic energy Ambassador melted battery internal diaphragm, negative direct short circuit, producing an explosion.

4. Spot welding exploded

Resistance spot welding currents caused serious internal short circuit produce an explosion, in addition to resistance spot welding for cathode connections directly associated with negative, polarity short circuit directly after an explosion.

5. Explosion

Battery discharge or discharge (3C) easy to make cathode copper dissolved deposition onto the diaphragm so that positive and negative short-circuit explode directly (rarely happens).

6. Vibrations fall explosion

Batteries in high vibration or drop batteries caused internal displacement, direct and serious short circuit and explosion (rare).

Six, the low battery 3.6V platform

1. Test sample no or low Cabinet instability test platform.

2. Ambient temperature too low causes low platform (discharge platform is greatly influenced by ambient temperature)

Seven, improper processing

(1) the move caused battery cathode cathode connections for spot welding connection is bad, so internal resistance of batteries.

(2) welding connection no Han, and contact resistance, so that the battery internal resistance.