a) Requirements
Forced internal short circuit test for cylindrical cells and prismatic cells shall not cause fire. Cell manufacturers shall keep a record to meet the requirements. A new design evaluation shall be done by the cell manufacturer after testing is conducted by the cell manufacturer or a third party test house. This country specific test which is only applicable to France, Japan, Korea and Switzerland and is not required on polymer cells.
b) Test
The forced internal short circuit test is performed in a chamber at +10℃ and +45 ℃ (ambient internal chamber temperature) according to the following procedure.
1) Number of samples
This test shall be carried out on five secondary (rechargeable) lithium-ion cells.
2) Charging procedure
i) Conditioning charge and discharge
The sample shall be charged at 20 •c ± 5 •c according to the manufacturer's recommendation. The sample is then discharged at 20 •c ± 5 •c at a constant current of 0,2 11 A down to the final voltage specified by the manufacturer.
ii) Storage procedure
Test cell shall be stored for 1 h to 4 h at an ambient temperature as specified in Table 5.
iii) Ambient temperature
Table 5- Ambient temperature for cell test a
iv) Charging procedure for forced internal short test Test cell shall be charged at an ambient temperature as specified in Table 5, at the upper limited charging voltage at the constant current specified by the manufacturer, continue charging at constant voltage at upper limited charge current drops to 0.05 It A.
3) Pressing the winding core with nickel particle Temperature-controlled oven and special press equipment are needed for the test. Moving part of the press equipment shall move at constant speed and can be stopped immediately when short-circuit is detected。
i) Preparation for the test
A The temperature of the oven is controlled as specified in Table 5. Samples preparation guidance is provided in Annex A, Clause A.5 and in Figure A.5 and Figure A.S. Put aluminum-laminated bag with winding core and nickel particle into the oven for 45 ± 15 min.
B Remove the winding core from sealed package and attach terminals for voltage measurement and thermo couple for temperature on the surface of the winding core. Set the winding core under the pressure equipment to locating the point of the place of the nickel particle under the pressing jig.
Remark: To prevent evaporation of electrolyte, finish the work within 10 min
from removing the winding core from the oven for temperature conditioning to
closing the oven door where the equipment is located.
C Remove insulating sheet and close the oven door.
ii) Internal short circuit
A Confirm that the winding core surface temperature is as defined in Table 5 and
then starts the test.
B Bottom surfac·e of moving part of the press equipment is made of Nitrile rubber
or Acryl, which is put on the 10 mm x 10 mm sta inless steel shaft. The detail of
pressing jigs shall be shown in Figure 2. Nitrile rubber bottom surface is for
cylindrical cell test. For prismatic test 5 mm x 5 mm (2 mm thickness) Acryl is
put on the Nitrile rubber. The fixture is moved down at the speed of 0,1 mm/s
monitoring the cell voltage. When voltage drop caused by the internal shortcircuit
is detected, stop descent immediately and keep pressing jig in the position for 30 s and then release the pressure. Voltage is monitored m-ore than
100 times per second and if voltage is dropped more than 50 m V compare to
the initial voltage, it is defined to internal short circuit has occurred. If the
pressure reaches BOO N for cylindrical cell and 400 N for prismatic cell, stop
descent immediately and then keep in the position.
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