For the lithium battery four mountains - heavy impact, extrusion, short circuit, overcharge related test

In the safety performance test of lithium ion batteries, heavy object impact, extrusion, short circuit, and overcharge test are the top items with the highest failure rate. This paper compares and analyzes the relevant test items involved in the IEC62660-2-2010 "secondarylithium-ioncellsforpropulsionofelectricroadvehicles", UL1642-2012 "standardforlithiumbatteries", "safety requirements for lithium-ion power batteries for electric vehicles".

From the analysis, at present, China's national standards for power batteries and GB31241 national standards for consumer batteries are based on foreign standards, and basically maintain consistency with foreign advanced standards.

1. IEC62660-2-2010 (the standard does not contain heavy impact test)

1) The extrusion test in this standard is carried out using a circular or semi-circular rod or a spherical or hemispherical extrusion tool having a diameter of 150 mm. For cylindrical batteries, round bars are recommended; for prismatic batteries, ball extrusion tools are recommended. When the voltage suddenly drops to 1/3 of the initial voltage or the deformation reaches 15% or more of the initial size or the force is 1000 times the mass of the battery, the pressing force should be released.

2) The external short-circuit test in this standard is short-circuited with a resistance of 5 milliohms or less for 10 minutes.

3) In this standard, the over-charging pure electric vehicle battery adopts 1It current, and the hybrid electric vehicle battery adopts 5It current. When the battery voltage reaches 2 times of the maximum voltage specified by the manufacturer or the amount of electricity applied to the battery core is reached. The test is over at 200% SOC.

4) The standard does not contain heavy impact testing.

2. UL1642-2012

1) Using the plate extrusion method, the pressing force is 13KN±1KN, which is basically the same as GB31241-2014.

2) Impacting the metal rod with a heavy object and applying pressure to the battery is basically the same as GB31241-2014.

3) The short-circuit resistance is 100 milliohms, which is basically the same as GB31241-2014.

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

3. "Safety Requirements for Lithium Ion power battery for Electric Vehicles"

1) Battery extrusion

Extrusion direction: pressing perpendicular to the direction of the cell monolithic plate, or the same direction as the lithium ion battery cell is most likely to be squeezed in the overall vehicle layout;

Extruded plate form: a semi-cylindrical body with a radius of 75 mm, the length (L) of the semi-cylindrical body is larger than the size of the extruded battery cell;

Extrusion speed: no more than 2mm / s;

Extrusion degree: stop the extrusion after the voltage reaches 0V or the deformation reaches 30% or the pressing force reaches 100kN;

Hold for 10 minutes. After the end of the test, it should be observed for 1 h at the test ambient temperature.

2) Short circuit of the battery

The positive and negative poles of the fully charged test object are short-circuited externally for 10 min, and the external line resistance should be less than 5 mΩ.

3) Battery over charge.

Charging is stopped after charging at a current constant current of 1I1 or a manufacturer and not less than I3 to 1.2 times or 120% SOC of the charge termination voltage specified by the manufacturer.

4) No heavy impact test

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