Conventional performance of 18650 lithium-ion battery.
Concept Introduction
C-rate
The charging and discharging of batteries are measured at the C-rate, The definition of 1C: For example, if the capacity of an 18650 battery is 1000mAh, 1C discharge means discharging at 1000mA, and 0.5C discharge means discharging at 500mA.
Rated capacity (specified in GB/T18287-2000):
The amount of electricity that a battery should provide when discharged at a 5-hour rate to the termination voltage at an ambient temperature of 20+/-5 degrees, denoted as C5. We usually take the discharge capacity at 0.2C as the actual discharge capacity.
Charging method:
First charge with constant current to 4.2V, then charge with constant voltage (in Japan's charging mode, constant voltage charging is used for 2.5 hours, and the national standard GB/T 18287 states that the charging current is cut-off when it is less than 0.01C5A)
Rate discharge performance:
Because lithium-ion batteries use organic solvent electrolytes, their conductivity is generally only a few hundred times that of lead-acid or alkaline battery electrolytes. Therefore, during high current discharge, lithium-ion batteries may not have enough time to replenish Li+from the electrolyte, resulting in a voltage drop (IR drop)
Low temperature discharge performance:
When the temperature is low, the discharge platform of
lithium-ion batteries decreases to a certain extent
Special attention should be paid to the presence of non-conductive crystal phases in lithium polymer batteries at low temperatures, and the conductivity of polymers directly depends on the number and motion of charge carriers. Therefore, the discharge platform of lithium polymer batteries is reduced even more
Cycle performance:
Lithium ion batteries have good cycling characteristics, generally maintaining around 80% of their capacity after 500 cycles
high temperature performance
Lithium ion batteries experience capacity degradation at high temperatures, which can be restored through low current charging and discharging
High temperature charging and discharging can affect the cycling performance of batteries and cause slight expansion
Batteries are generally recommended to operate within the range of 0-40 degrees
