极品斗地主

Ten questions about the basic knowledge of lithium batteries (1)

- Dec 05, 2018-

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1。 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 design or manufacture of the battery to stipulate or ensure that the battery should emit a minimum amount of electricity under certain discharge conditions. Li-ion stipulates that the battery is charged for 3 hours under normal temperature and constant current (1C) constant voltage (4.2V) controlled charging conditions. The actual capacity of the battery refers to the actual amount of electricity discharged by the battery under certain discharge conditions, mainly due to the discharge rate. And the effect of temperature (so strictly speaking, the battery capacity should indicate the charge and discharge conditions). Common units of capacity are: mAh, Ah = 1000mAh).


2. What is the internal resistance of the battery?

It refers to the resistance that current flows through the inside of the battery while the battery is in operation。 It has two parts: ohmic internal resistance and polarization internal resistance。 The large internal resistance of the battery will cause the battery discharge operating voltage to decrease and the discharge time to be shortened。 The internal resistance is mainly affected by factors such as the material of the battery, the manufacturing process, and the structure of the battery。 It is an important parameter to measure battery performance。 Note: Generally, the internal resistance of the state of charge is the standard。 Measuring the internal resistance of the battery requires a special internal resistance meter and cannot be measured with a multimeter ohmmeter。


3. What is the open circuit voltage?

It refers to the potential difference between the positive and negative terminals of the battery when the battery is not in operation, that is, when there is no current flowing through the circuit。

Under normal circumstances, the open circuit voltage of Li-ion is about 4.1-4.2V after full charge, and the open voltage after discharge is about 3.0V. The open state voltage of the battery can be used to judge the state of charge of the battery.


4。 What is the working voltage?

Also known as terminal voltage, it refers to the potential difference between the positive and negative terminals of the battery when the battery is in operation, that is, when there is current in the circuit. In the battery discharge working state, when the current flows through the inside of the battery, it is not necessary to overcome the resistance caused by the internal resistance of the battery, so the working voltage is always lower than the open circuit battery, and the charging is reversed. Li-ion's discharge operating voltage is around 3.6V.


5。 What is a discharge platform?

The discharge platform is a discharge time when the constant voltage is charged to a voltage of 4.2 V and the electric current is less than 0.01 C, and then discharged for 10 minutes, and discharged at a discharge current of any rate to 3.6 V. It is an important criterion for measuring the quality of a battery.


6. What is the (charge and discharge) rate?

Refers to the current value required by the battery to discharge its rated capacity within the specified time. It is equal to the multiple of the rated capacity of the battery in the data value, usually indicated by the letter C. For example, the nominal capacity of the battery is 600 mAh for 1 C (1 rate), 300 mAh for 0.5 C, 6 A (600 mAh) for 10 C. and so on.

The time rate is also called the hourly rate. It refers to the number of hours required for the battery to discharge its rated capacity with a certain current. If the rated capacity of the battery is 600mAh, it takes 1 hour to discharge its rated capacity at 600mAh, so it is called 600mAh. The current is 1 hour, and so on.


7. What is the self-discharge rate?

Also known as the charge retention capability, it refers to the ability of the battery to maintain the power stored under certain conditions under open conditions. Mainly affected by factors such as battery manufacturing process, materials, storage conditions. It is an important parameter to measure battery performance.

Note: After the battery is 100% charged open, a certain degree of self-discharge is normal。 After the LI-ion is specified in the GB standard, it is left open for 28 days under the condition of 20±2 °C。 The battery can be allowed to have a loss in capacity。


8。 What is internal pressure?

Refers to the internal air pressure of the battery, which is caused by the gas generated during the charging and discharging process of the sealed battery, and is mainly affected by factors such as battery material, manufacturing process, and battery structure. The reason for this is mainly due to the accumulation of gas inside the battery and the gas generated by the decomposition of the organic solution in the battery.

High-rate continuous overcharging will cause the battery temperature to rise and the internal pressure to increase。 In severe cases, it will have destructive effects on the performance and appearance of the battery, such as liquid leakage, drum bottom, increased internal resistance of the battery, discharge time and cycle life。 Shorten and so on。

Any form of Li-ion can cause serious damage to battery performance and even explosion。 Help Li-ion to use constant current and constant voltage charging during charging to avoid overcharging the battery。


9. Why does the battery have to be stored for a while before it can be packaged for shipment?

The storage performance of the battery is an important parameter to measure the stability of the overall performance of the battery. After the battery has been stored for a certain period of time, the capacity and internal resistance of the battery are allowed to change to some extent. After a period of storage, the electrochemical performance of the internal components can be stabilized, and the self-discharge performance of the battery can be understood to ensure the quality of the battery.


10. Why do you want to turn it into?

After the battery is manufactured, the internal positive and negative materials are activated by a certain charge and discharge method, and the process of improving the charge and discharge performance of the battery and the comprehensive performance of self-discharge and storage is called formation, and the battery powder can be converted into a real performance.


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