Some common questions about 16340 battery

1. How is the safety feature of lithium ions achieved?

1) The 135℃ automatic shutdown protection of the diaphragm adopts the internationally advanced Celgars2300PE-PP-PE three-layer composite film. When the battery temperature reaches 120℃, the membrane pores on both sides of the PE composite film are closed, the internal resistance of the battery increases, and the internal temperature rise of the battery slows down. When the battery temperature reaches 135℃, the PP membrane pores are closed, the internal circuit of the battery is broken, and the battery no longer heats up, ensuring the safety and reliability of the battery.

2) Adding additives to the electrolyte When the battery is overcharged and the battery voltage is higher than 4.2V, the electrolyte additives and other substances in the electrolyte polymerize, the internal resistance of the battery increases significantly, a large area of breaks the battery, and the battery no longer heats up.

3) Composite structure of battery cover The battery cover adopts a notched explosion-proof ball structure. When the battery heats up, part of the gas generated during the activation process inside the battery expands, the internal pressure of the battery increases, and the pressure reaches a certain level. The notch ruptures and deflates.

4) Various environmental abuse tests are carried out to test the safety performance of the battery, such as external short circuit, overcharge, puncture, impact, incineration, etc. At the same time, the battery is subjected to temperature shock tests and mechanical performance tests such as vibration, drop, and impact to examine the performance of the battery in the actual use environment.

2. Why does the constant voltage charging current gradually decrease?

Because when the constant current process ends, the electrochemical polarization inside the battery remains at the same level throughout the constant current. During the constant voltage process, under the action of a constant electric field, the internal Li+ concentration polarization is gradually eliminated, and the number and speed of ion migration are manifested as a gradual decrease in current.

3. What is the capacity of the battery?

The capacity of the battery is divided into rated capacity and actual capacity. The rated capacity of the battery refers to the minimum amount of electricity that should be discharged under certain discharge conditions when the battery is designed and manufactured. Li-ion stipulates that the battery is charged for 3 hours under the charging conditions of constant current (1C) and constant voltage (4.2V) at room temperature. The actual capacity of the battery refers to the actual amount of electricity discharged by the battery under certain discharge conditions, which is mainly affected by the discharge rate and temperature (so strictly speaking, the battery capacity should indicate the charging and discharging conditions). Common units of capacity are: mAh, Ah=1000mAh).

4. What is the internal resistance of the battery?

It refers to the resistance encountered by the current flowing through the battery when the battery is working. It consists of two parts: ohmic internal resistance and polarization internal resistance. A large internal resistance of the battery will lead to a lower discharge voltage and a shorter discharge time. The size of the internal resistance is mainly affected by factors such as the battery material, manufacturing process, and battery structure. It is an important parameter for measuring battery performance. Note: Generally, the internal resistance in the charged state is used as the standard. The internal resistance of the battery needs to be measured with a special internal resistance meter, and cannot be measured with the ohm range of a multimeter.

5. What is open circuit voltage?

The open circuit voltage is about 4.1-4.2V after full charge, and about 3.0V after discharge. The open circuit voltage of the battery can be used to determine the state of charge of the battery. What is the working voltage? The discharge working voltage is about 3.6V.

6. What is internal pressure?

Refers to the internal gas pressure of the battery, which is caused by the gas generated by the sealed battery during the charging and discharging process, and is mainly affected by factors such as battery materials, manufacturing processes, and battery structure. The main reason for its generation is that the gas generated by the decomposition of water and organic solutions inside the battery accumulates in the battery. Continuous overcharging at a high rate will cause the battery temperature to rise and the internal pressure to increase. In severe cases, it will have a destructive effect on the performance and appearance of the battery, such as leakage, bulging bottom, increased internal resistance of the battery, and shortened discharge time and cycle life. Any form of overcharging of Li-ion will cause serious damage to the battery performance and even explosion. Li-ion needs to adopt constant current and constant voltage charging during the charging process to avoid overcharging the battery.

7. Why do batteries have to be stored for a period of time before they can be packaged and shipped?

The storage performance of the battery is an important parameter to measure the stability of the battery's comprehensive energy. After a certain period of storage, the battery's capacity and internal resistance are allowed to change to a certain extent. After a period of storage, the electrochemical properties of the internal components can be stabilized, and the size of the battery's self-discharge performance can be understood to ensure the quality of the battery.

8. Why is formation necessary?

After the battery is manufactured, the internal positive and negative electrode materials are activated through a certain charging and discharging method to improve the battery's charging and discharging performance and self-discharging, storage and other comprehensive performance. The process is called formation. The battery powder can only reflect its true performance after formation.

9. What is capacity division?

During the manufacturing process of the battery, due to process reasons, the actual capacity of the battery cannot be completely consistent. Through a certain charging and discharging system, the process of testing and classifying the battery by capacity is called capacity division.

10. What is voltage drop?

The battery is qualitatively charged to more than 80%, and its battery no-load voltage is measured. The 5W/2W battery is connected as a load to the positive and negative end switches of the battery as the battery's circuit breaker and the device for the path is connected in series. The voltage drop is no more than 0.4V within 5 seconds after the switch is turned on, which is qualified. It is mainly used to test the battery load performance.

11. What is static resistance?

That is, the internal resistance of the battery during discharge. What is dynamic resistance? That is, the internal resistance of the battery during charging.

12. Ultrasonic welding machine is used for the positive electrode and spot welding machine is used for the negative electrode.

13. The purpose and position of the battery core sticker?

The position of the battery core sticker is not deformed after the battery core is wound. The bottom sticker prevents the bottom of the positive electrode in the battery core from contacting the battery shell and causing a short circuit. The side sticker prevents the battery core from deforming after winding. The bottom sticker prevents the bottom of the positive electrode in the battery core from contacting the battery shell and causing a short circuit.

14. What is the humidity requirement for the drying room? The relative humidity is below 6%.

15. Why should the battery be weighed before filling? In order to accurately calculate the amount of liquid to be filled.

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