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What are the main structural components of lithium-ion batteries

The main components of lithium-ion batteries are upper and lower battery covers, positive electrode sheet (active material is lithium cobalt oxide), separator (a special composite membrane), the negative electrode (active material is carbon), organic electrolyte, battery case (divided into two kinds of steel shell and aluminum shell) and so on.

1.  internal resistance of the battery

It refers to the resistance experienced by the current flowing through the battery when the battery is working. It is composed of ohmic internal resistance and polarization internal resistance. The large internal resistance of the battery will reduce the battery discharge working voltage and shorten the discharge time. The internal resistance is mainly affected by the battery material, manufacturing process, battery structure, and other factors. It is an important parameter to measure battery performance. Note: Generally, the internal resistance in the charged state is the standard. To measure the internal resistance of the battery, a special internal resistance meter should be used instead of a multimeter in the ohm range.

2.  Nominal Voltage

The nominal voltage of the battery refers to the voltage exhibited during normal operation. The nominal voltage of the secondary nickel-cadmium nickel-hydrogen battery is 1.2V; the nominal voltage of the secondary lithium battery is 3.6V. LTO Battery Voltage is 2.3V, Lifepo4 Battery is 3.2V

3.  Open Circuit Voltage

Open circuit voltage refers to the potential difference between the positive and negative electrodes of the battery when the battery is in a non-working state, that is when there is no current flowing through the circuit. Working voltage, also known as terminal voltage, refers to the potential difference between the positive and negative poles of the battery when the battery is in working state, that is, when there is over current in the circuit.

4. Battery Capacity

The capacity of the battery is divided into the rated capacity and the actual capacity. The rated capacity of the battery refers to the stipulation or guarantee that the battery should discharge the minimum amount of electricity under certain discharge conditions during the design and manufacture of the battery. The IEC standard stipulates that nickel-cadmium and nickel-metal hydride batteries are charged at 0.1C for 16 hours and discharged at 0.2C to 1.0V at a temperature of 20°C ± 5°C. The battery's rated capacity is expressed as C5. For lithium-ion batteries, it is stipulated to charge for 3 hours under normal temperature, constant current (1C)-constant voltage (4.2V) control charging conditions, and then discharge at 0.2C to 2.75V when the discharged electricity is its rated capacity. The actual capacity of the battery refers to the actual power released by the battery under certain discharge conditions, which is mainly affected by the discharge rate and temperature (so strictly speaking, the battery capacity should specify the charge and discharge conditions). The unit of battery capacity is Ah, mAh (1Ah=1000mAh).

5. Residual Discharge Capacity of the Battery

When the rechargeable battery is discharged with a large current (such as 1C or above), due to the "bottleneck effect" existing in the internal the diffusion rate of the current over current, the battery has reached the terminal voltage when the capacity is not fully discharged, and then uses a small current such as 0.2C can continue to discharge until 1.0V/piece (nickel-cadmium and nickel-hydrogen battery) and 3.0V/piece (lithium battery), the released capacity is called residual capacity.

6.Discharge Platform

The discharge platform of Ni-MH rechargeable batteries usually refers to the voltage range in which the battery's working voltage is relatively stable when the battery is discharged under a certain discharge system. Its value is related to the discharge current. The larger the current, the lower the value. The discharge platform of lithium-ion batteries is generally to stop charging when the voltage is 4.2V and the current is less than 0.01C at a constant voltage, then leave it for 10 minutes, and discharge to 3.6V at any rate of discharge current. It is an important criterion for measuring the quality of batteries.