Analysis of common lithium battery problem causes and solutions

A, the voltage is inconsistent, a single low

Large self-discharge of the cell, so that its voltage drop faster than other, low voltage can be eliminated after storage to check the voltage.

After battery testing in the charge, because of contact resistance or testing cabinet charge current inconsistent formation of uneven cell charge. In the short time storage (12 hours) measured voltage difference is very small, but long-term storage voltage difference is larger, this low voltage and no quality problems, can be processed through charging. In the production of the charge after storage for more than 24 hours to measure the voltage.

 

Second, the reason

1、Different testing equipment formation

2、The storage time is too long

3. abnormal heat formation of internal resistance

 

Three, lithium battery swelling

 

Forklift lithium battery in charging, lithium battery will naturally swell, but generally not more than 0.1mm, but overcharging will form electrolyte differentiation, internal pressure increases, lithium battery swelling. Generally, processing abnormalities (such as short circuit, overheating, etc.) form internal overheating electrolyte differentiation, and the lithium battery swells up.

 

Battery in the cycle, the thickness will follow the cycle times to add, but beyond 50 weeks after the basic is not added, the general normal increase in the amount of 0.3 to 0.6 mm, aluminum shell is more serious, this phenomenon belongs to the normal battery reactions formed. But if you add shell thickness or reduce the internal material can properly reduce the swelling phenomenon.

The voltage of the aluminum shell battery cell is lower than 3.7V after spot welding, generally because the spot welding current is too large resulting in the short circuit of the internal compartment of the battery cell, forming a voltage drop too fast.

 

After spot welding battery power loss is also partly due to the formation of the larger self-discharge of the battery itself.

 

Fourth, the occurrence of power lithium battery burst generally has the following several situations.

Maintenance line out of control or testing cabinet out of control so that the charging voltage is greater than 5V, the formation of electrolyte differentiation, the battery internal reactions, the battery pressure rises rapidly, the battery burst.

Maintenance line out of control or testing cabinet out of control so that the charging current is too large to form lithium ions too late to embed, and the formation of lithium metal on the surface of the pole piece, penetrating the barrier, the positive and negative electrodes directly short-circuit the formation of burst (rarely occur).

Ultrasonic welding plastic shell, because of the equipment so that its ultrasonic energy transfer to the battery core, ultrasonic energy is very large so that the battery internal barrier melted, positive and negative electrodes directly short-circuit, bursting.

Spot welding when the current is too large to form a severe internal short circuit, bursting, and other, spot welding when the positive pole connecting piece directly connected to the negative pole, so that the positive and negative poles directly short-circuited burst.

Battery over-discharge or over-current discharge (more than 3C) can easily make the negative copper foil dissolved and deposited on the barrier, so that the positive and negative electrodes directly short-circuit and burst (rarely occurs).

The cores are misaligned when they oscillate violently or fall, resulting in a direct severe short circuit and bursting (rarely occurs).

Testing cabinet sampling inhibition or testing cabinet is not stable to form a low test channel.

 

 

Five, processing improperly formed

Spot welding connection piece is not welded firmly, the contact resistance is large, so that the battery internal resistance is large.