The four mountains tested by the lithium core are heavy objects impact, squeeze, short circuit, overcharge

In the safety performance test of lithium-ion batteries, impact, extrusion, short-circuit and overcharging tests of heavy weights are the items with the highest failure rate. This article analyzes the test items related to the standards in IEC 62660-2-2010 "secondylithium-universityanalysis", UL1642-2012 "statardforlithiumbatteries", "Lithium-ion battery safety requirements for electric vehicles", etc..

From the analysis, at present, China's power cell national standard and GB31241 consumer battery national standard key projects have referred to foreign standards, basically maintained the consistency with foreign advanced standards.

1, IEC 62660-2-2010(this standard does not contain heavy impact test)

1) The extrusion test in this standard uses a round or semicircular bar or a spherical or hemispherical extrusion tool with a diameter of 150 mm. For cylindrical batteries, round rods are recommended; For Prismatic batteries, spherical extrusion tools are recommended. When the voltage burst falls to 1/3 of the initial voltage or the deformation amount reaches 15 % or more of the initial size, or the force is 1000 times the battery mass, the squeeze pressure should be released.

2) The external short-circuit test in this standard uses a resistance of less than or equal to 5 mm for 10 minutes.

3) In this standard, 1It current is used for the pure electric vehicle core in overcharge, and 5It current is used for the hybrid electric vehicle core. The test is completed when the core voltage reaches 2 times the maximum voltage specified by the manufacturer or the amount of electricity applied to the core reaches 200 % SOC.

4) The standard does not contain heavy impact tests.

2, UL1642-2012

1) Using flat plate extrusion, the squeeze pressure is 13KN ± 1KN, which is basically the same as GB31241-2014.

2) Use heavy weights to hit the metal rod to put pressure on the battery, which is basically the same as GB31241-2014.

3) Short circuit resistance 100 mm, which is basically the same as GB31241-2014.

4) 3 times the maximum charging current recommended by the manufacturer, 7H, which is basically the same as GB31241-2014.

3, "Safety Requirements for Lithium-ion power battery for Electric Vehicles" Consultation Draft

1) Core Squeeze

Squeeze direction: Vertical to the direction of pressure on the battery monomer plate, or the same direction as the lithium-ion battery monomer is most likely to be squeezed in the layout of the vehicle;

Extrusion plate form: a semi-cylinder with a radius of 75mm, and the length(L) of the semi-cylinder is greater than the size of the compressed battery monomer;

Extrusion speed: not more than 2mm/s;

The extrusion degree: The voltage reaches 0V or the deformation amount reaches 30 % or the extrusion pressure reaches 100 kN and stops the extrusion;

Keep it 10 min. At the end of the test, 1 h shall be observed at the test ambient temperature.

2) Short circuit of the core

The positive and negative electrodes of the test object will be short-circuited by the external 10min, and the external line resistance should be less than 5mΩ.

3) Overcharge of the core

Stop charging after charging the current constant current specified by 1I1 or manufacturer and not less than I3 to 1.2 times or 120 % SOC of the charging termination voltage specified by manufacturer.

4) No Heavy Impact Test

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