How are lithium-ion safety features achieved?
a. The diaphragm iautomatically shut off protection at 135°C, and the internationally advanced Celgars2300PE-PP-PE three-layer composite film is used. When the temperature of the battery reaches 120 °C, the membrane pores on both sides of the PE composite film are closed, the internal resistance of the battery increases and the temperature inside the battery slows down. When the temperature of the battery reaches 135°C, the PP film pores are closed, the internal circuit of the battery is disconnected, and the battery does not heat up anymore, ensuring the safety and reliability of the battery.
b. Add additives to the electrolyte when the battery overcharged and the battery voltage is higher than 4.2V, the electrolyte additives and other substances in the electrolyte polymerization. The internal resistance of the battery increases greatly, and a large area of the battery is broken. The battery stops heating up.
c. Battery cover composite structure The battery cover adopts a notch explosion-proof ball structure. When the battery heats up, part of the gas generated during the internal activation process of the battery expands, the internal pressure of the battery increases, and the pressure reach a certain level.
d.Various environmental abuse tests conducted for various abuse experiments, such as external short circuit, overcharge, pinprick, impact, incineration, etc., to examine the safety performance of the battery. At the same time, the temperature shock test and vibration, drop, impact and other mechanical performance experiments conducted on the battery to examine the performance of the battery in the actual use environment.
Why does the constant voltage charging current gradually decrease?
Because the constant current process is end, the electrochemical polarization inside the battery keep at the same level again throughout the constant current, the constant voltage process. And then under the effect of the constant electric field, the internal Li+ concented polarization is gradually eliminated. and the movement number and speed of ions are shown as a gradual reduce in current.
What is the capacity of the battery?
The capacity of the battery divid into the rated capacity and the actual capacity. The rated capacity of the battery refers to the design and manufacture of the battery that stipulates or guarantees. The battery should discharge the minimum amount of electricity under certain discharge conditions. Li-ion stipulates that the battery should charged for 3 hours under the charging conditions controlled by normal temperature, constant current (1C), and constant voltage (4.2V). And the influence of temperature (so strictly speaking, the battery capacity should specify the charging and discharging conditions). Common units of capacity are: mAh, Ah=1000mAh).
What is the internal resistance of the battery?
Refers to the resistance of the current flowing through the battery when the battery is working. It consists of ohmic internal resistance and polarization internal resistance. The large internal resistance of the battery will cause the battery discharge working voltage to reduce and the discharge time to be shortened. The internal resistance is mainly affected by factors such as battery material, producing process, and battery structure. It is an important parameter to measure battery performance.
Please note: Generally, the internal resistance in the charging state using as the standard. And the internal resistance of the battery needs to measure with a special internal resistance meter, not with the ohm gear of a multimeter.
What is open circuit voltage OCV?
The open circuit voltage is about 4.1~4.2V after full charge, and the open circuit voltage is about 3.0V after discharging. Through the open circuit voltage of the battery, the state of charge of the battery can judged. What is the working voltage? The discharge working voltage is around 3.6V.
What is the internal air pressure of the battery?
It refers to the internal air pressure of the battery, which caused by the gas generated during the charging and discharging process of the sealed battery. And mainly affected by factors such as battery material, producing process, and battery structure. While the main reason is that the gas created by the decomposition of moisture. And organic solution inside the battery accumulates in the battery.
Meanwhile continuous overcharge at a high rate will cause the temperature of the battery to increase and the internal pressure to increase. And in severe cases, it will have a destructive effect on the performance and appearance of the battery, such as liquid leakage, drum bottom, increase in the internal resistance of the battery, discharge time, and cycle life. shorten etc. Any form of overuse of Li-ion will cause serious damage to battery performance, or even an explosion. Help Li-ion to use constant current and constant voltage charging methods during the charging process to avoid overcharging the battery
Why does the battery need to be stored for a period of time before it can be packaged and shipped?
The storage performance of the battery is an important parameter to measure the stability of the comprehensive performance of the battery. After a certain period of storage, the battery allows having a certain degree of change in capacity and internal resistance. After a period of storage, the electrochemical properties of the internal components can stabilize. And the size of the self-discharge performance of the battery can understand in order to ensure the quality of the battery.
Why should it be transformed?
After the battery is produced, the internal positive and negative materials are activated by a certain charging and discharging method. And the process of improving the battery’s charging and discharging performance, self-discharge, and storage.
And another comprehensive performance is formation, in which the battery power can only reflect its true performance after formed.
What is separating?
During the producing process of the battery, the actual capacity of the battery cannot be entirely uniform due to technological reasons. And the process of classifying the battery by capacity is separator through a certain charge-discharge system test.
What is pressure drop?
Battery charged to 80% or more on a qualitative basis. And to measure the no-load voltage of the battery. 5W/2W battery as a load connected to the positive and negative extremes of the battery switch as a battery disconnect. Then connect the devices in the channel in series. Open the switch after 5 seconds voltage drop is not more than 0.4V, for qualified mainly for testing the battery load performance.
What is static resistance? What is dynamic resistance?
a. Static resistance is the internal resistance of the battery during discharge.
b. Dynamic resistance is the internal resistance of the battery during charging.
What welding methods are used for the positive and negative electrodes?
a. Ultrasonic welding machine for the positive electrode.
b. Spot welding machine for the negative electrode.
What is the purpose and location of the battery cell sticker?
a. The position of the battery core sticker will not deformed after the battery core wound and formed. And sticking tape on the bottom prevents the bottom of the positive plate in the battery cell from contacting the battery case and causing a short circuit.
b. The side stickers make the cells not deformed after wounding and formed. Sticking tape on the bottom prevents the bottom of the positive plate in the cell from contacting the battery case and causing the battery to short circuit.
Why should the battery be weighed before liquid injection?
a. In general the relative humidity is below 6%.
b. In order to accurately calculate the amount of liquid injection.
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