
What are the main structural components of lithium-ion batteries?
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.