Lithium battery energy storage power supply ten main parameters of lithium ion battery

Lithium ion battery is the core of lithium battery energy storage power supply. The main parameters usually refer to the electrical performance, mechanical performance and storage performance parameters. Electrical performance: electromotive force, open circuit voltage, working voltage, internal resistance, charging voltage, capacitance, specific energy (ratio) and service life, etc.

1. Electromotive force

The electromotive force of the battery, also known as the battery standard voltage or theoretical voltage, is the potential difference between the positive and negative poles when the battery is open circuit (no current flows through the external circuit).

2. Voltage

Lithium ion battery voltage: parameters include open circuit voltage, termination voltage, working voltage and charging voltage.

Open circuit voltage: refers to the potential difference between the positive and negative electrodes of the battery when there is no current flowing through the external circuit. Generally, the open circuit voltage is less than the battery electromotive force.

Termination voltage: the lowest point voltage or the highest charging voltage of a battery when it is in a hotel or charging. For a secondary battery such as a lithium-ion battery, the termination voltage is determined on the basis of considering the battery capacity and cycle stability. In the case of low temperature or high current discharge, due to the serious polarization, in order to make full use of the active materials, the end voltage of charging and discharging is usually set wider.

Working voltage: also known as discharge voltage or load voltage, refers to the potential difference between the battery electrodes when the current passes through the external circuit, which is the actual output voltage of the battery in the operation process. Its size changes with the current and discharge degree in the range between the open circuit voltage and the termination voltage.

Charging voltage: for secondary battery charging only, it is the terminal voltage of the secondary battery during charging. In the case of constant current charging, the charging voltage increases with the charging time. In the case of constant voltage charging, the charging current decreases rapidly with the charging time.

3. The internal resistance of battery is an important parameter to measure the performance of battery. The large internal resistance of battery will reduce the working voltage of battery when discharging, increase the internal energy loss of battery, and aggravate the heating of battery. The internal resistance of battery is mainly affected by many factors, such as battery material, manufacturing process, battery structure and so on.

4. Capacitance

The capacity unit of the battery is ah, including theoretical capacity (refers to the amount of electricity calculated according to the electrochemical equivalent book of active substances participating in electrochemical reaction), rated capacity (refers to the minimum amount of electricity that the battery should discharge under the specified discharge conditions in the design and production of the battery), and actual capacity (refers to the amount of electricity that the battery should discharge under certain discharge conditions, i.e. under certain discharge conditions) The amount of electricity discharged by the terminal voltage of the battery at current and temperature.

5. Energy and specific energy

Refers to the electric work that the battery can do under certain discharge conditions. It is equal to the product of the discharge capacity of the battery and the average working voltage of the battery, expressed in wh.

6. Power and specific power

Refers to the energy output of the battery in unit time under certain discharge conditions, in watts (W) or (kw). The power per unit mass or volume of a battery is called the specific power of the battery.

7. Discharge current

When talking about battery capacity or energy, it is necessary to point out the discharge current or discharge condition, which is usually expressed by discharge rate. Discharge rate refers to the speed of discharge, which is often expressed by "time rate" and "rate".

8. Coulomb efficiency

It is also called charge discharge efficiency, which is expressed as the percentage of discharge and charge. It is an important parameter to characterize the charge reversibility of secondary battery and determine the battery life.

9. Storage performance and self discharge

Refers to the battery open circuit, under certain conditions (such as temperature, humidity, etc.) stored for a certain time after the size of self discharge. Although the battery does not release any energy during storage, there is always self discharge in the battery.

10. Battery life of lithium battery energy storage power supply

For primary batteries, the battery life mainly refers to the shelf life, that is, the time required to get the specified performance index after the battery is placed under the condition of no load.