Cell separation method 18650

IFR18650E1500mAh battery is introduced in detail. Although it is 18650 battery, it is cylindrical battery like 18650 battery. It must be classified according to grade and batch number.

The sorting method of cylindrical 18650 lithium battery core is as follows:

After loading the cabinet, follow the following steps.

1) put the upper cabinet aside for 2min to get the termination voltage, the termination voltage < 2.5v, directly lower the cabinet to C file for scrap.

2) 0.5c (1500mA) constant current, voltage limit 2.0v, time limit 150min;

3) let sit for 10min;

4) 0.1c (300mA) constant current, voltage limit 2.0v, time limit 60min;

5) let sit for 2min;

6) 0.5c constant current charging, voltage limit 3.65v, time limit 150min;

7) 3.65v constant voltage charging, current cut-off: 0.05c (150mA), time limit of 90min;

8) let sit for 2min;

9) 0.5c constant current, voltage limit 2.0v, time limit 150min;

10) let stand for 10min;

11) 0.1c constant current, voltage limit 2.0v, time limit 60min;

12) let sit for 2min;

13) 0.5c constant current charging, voltage limit 3.65v, time limit 60min;

Note: 0.5c =0.5* nominal capacity 0.1c =0.1* nominal capacity 0.05C=0.05* nominal capacity (and so on)

(work step 2+ work step 4) is the residual capacity of the cell, (work step 9+ work step 11) is the actual capacity.

Self-discharge test method =2* (nominal capacity *0.5 -- residual capacity)/((working step 9+ working step 11) * number of months in use)

At the end of the above steps, the actual capacity of the cell and self-discharge are assembled. 12 hours after the end of the working step, fully check the circuit voltage and internal resistance, and group the voltage and internal resistance.

Sorting data processing needs to retain the capacity data of power step 9, 0.5c (1500mAh) constant current 3.2v platform, the capacity using this capacity/power step 9 needs >=40%, for example: power step 9, 0.5c (1500mAh) constant current 3.2v platform capacity =1800mAh, power step 9 capacity =3200mAh, calculation method: 1800/3200=56%, that is qualified cell, if less than 40%, that is unqualified cell

The cells are required to be assembled (120pcs) according to the chemical composition tolerance batch. The requirements for the assembly are: 0.5c + 0.1c capacity 3000mAh voltage 3.290V internal resistance 30 milliohms, monthly self-discharge 10%. 30 mah first gear capacity, internal resistance plus or minus 2 m Ω, voltage plus or minus 2 mv, self-discharge tolerance + / - 1%.

Self discharge, internal resistance and retest the unqualified cell capacity, according to the standard document. The original batch and the date of reinspection cannot be matched with the cell identification.

Cell capacity is affected by temperature. If the temperature is below 22 degrees Celsius, the temperature compensation shall be calculated. The compensation method shall be implemented in accordance with the "lithium battery semi-finished product - guidelines on compensation for factors affecting the capacity", a controlled r&d document.