The new GB 31241-2022 lithium battery testing standard, 18650 pack builder "Safety Specifications for Portable electronic lithium-ion Batteries and battery Packs," released on December 29, 2022, was officially implemented on January 1, 2024. The formulation, promulgation and implementation of relevant safety standards contribute to the healthy and sustainable development of the lithium-ion battery industry.

Lithium-ion batteries in the transportation, battery manufacturing machine storage, use and recycling process, external factors such as high temperature, overcharge, overdischarge, short circuit, etc., will cause safety problems, such as battery leakage, fire and even explosion. As a result, GB 31241-2022 "Technical Specification for the Safety of Lithium-ion Batteries and accumulators for Portable Electronic Products" provides that this introduction is intended to introduce the principles on which the requirements of this document are based and to understand that these principles are necessary for the design and production of safe lithium-ion batteries and accumulators. It is important to note that this document only considers the most basic safety requirements for lithium-ion batteries and battery packs to provide safety protection for people and property, and does not address performance and functional characteristics.

Further research and development of information technology and processes will inevitably require further revision of this document. li ion battery construction Hazards arising from lithium-ion power batteries and battery packs within the scope of this document are:

Leaks, which can directly lead to chemical corrosion on the human body, or indirectly lead to failure of the internal insulation of battery-powered electronics

Danger of electric shock, fire, etc. :

Fire, which directly burns the human body, or poses a fire hazard to battery-powered electronic products; - Explosion, direct injury to human body or damage to equipment;

Overheating, causing direct burns to the human body, or resulting in reduced insulation levels and safety component performance, or flammable liquid combustion. The risk of leakage may be caused by internal or external stress under the action of shell damage. The danger of fire and explosion may be caused by thermal runaway inside the battery. The internal short circuit of the battery and the strong oxidation reaction of the battery material may cause thermal runaway.

In determining which instructional design research approach to adopt for batteries or battery packs, follow the following priorities;

First of all, if possible, give priority to the development of materials with high safety, and try to avoid materials that are easy to lead to thermal runaway in the process of enterprise use;

Second, if the above principles cannot be implemented, then it is necessary to design protective devices to reduce or eliminate the possibility of danger, such as installing protective devices;

Finally, if the above and other measures do not completely avoid the occurrence of hazards, then the remaining hazards need to be marked.

And explain the measures.

In summary, the battery must pass the corresponding safety test in strict accordance with the requirements, the safety test items specified in GB 31241-2022 "Portable electronic lithium-ion batteries and batteries, Safety Technical Specifications" are:

Low Pressure

After the battery is fully charged according to the test method specified in 451, it is placed in a direct box at 20 ° C ±5 ° C. After vacuuming, the pressure in the box is reduced to 11.6 kPa(simulated altitude of 15±240m) and maintained for 6 hours.

Specific analysis test research methods can be in accordance with the relevant laws in GB/T 2423.21. Battery should not fire, explosion, leakage.

Temperature Cycle

Increase the temperature of the test chamber to 72 ° C + 2 ° C and maintain it for 6 hours; b) Reduce the temperature of the test chamber to -40 degrees Celsius + 2 degrees Celsius and maintain it for 6 hours; C) Repeat steps a) to B) for 10 cycles;

Store at room temperature of 20 ° C to 5 ° C for at least 6 hours.

The conversion time between each two temperatures during the test is not more than 30 minutes, as shown in the schematic diagram of the steps in Figure 3. The specific test methods shall be carried out in accordance with the relevant provisions of GB/T 2423.22.

Vibration

Twelve cycles are performed in each direction, with a total cycle time of 3h in each direction.

Cylindrical and button batteries are analyzed according to their axial and radial development directions, and square and flexible packaging batteries are studied according to the three aspects of mutual vertical direction information vibration tests.

The specific test methods shall be carried out in accordance with the relevant provisions of GB/T 2423.10. The battery must not catch fire, explode, or leak liquid.

Acceleration Impact

The fully charged battery was fixed on the shock table to carry out the half-sinusoidal pulse shock test. In the first 3ms, the minimum average acceleration is 75g, the peak acceleration is 150g, and the pulse duration is 6ms and 1ms. The battery is subjected to three accelerated shock tests in each direction.

Axial and radial impact tests were carried out on cylindrical and button-shaped batteries, and three vertical impact tests were carried out on square and flexible pack batteries.

Specific test methods in accordance with the relevant provisions of GBu002FT 2423.5.

Fall

After the battery can be fully charged according to the test and research method specified in 4.5.1, it falls to a height of 1m and falls into free fall on a concrete slab in China.

A total of four drip tests were performed on the cylinder and button batteries, one drop per end face, two drops on the cylinder face, and one drop per end face on the square and flexible packaging batteries, a total of six drip tests were performed.

The battery should not catch fire or explode.

Extrusion

After the battery is charged in accordance with the test method specified in 451, the battery is placed on two planes and squeezed vertically in the direction of the dry plate.

A extrusion pressure of 13.0KN0.78KN was applied between the two plates. The speed of the extruded battery is 0.1 mm/s. Once the pressure reaches its maximum or the battery voltage drops by one-third, the squeeze test can be stopped. During the test, the battery should be protected from external short circuits.

The vertical axis of the cylindrical battery is parallel to the two plates when it is extruded, and the button battery can be studied by means of the traditional battery enterprise with the upper and lower sides parallel to the two plates. Square battery (hard shell), the length is generally less than 25mm square flexible packaging battery development and other types including battery systems only the wide side of the battery for continuous extrusion test. For square flexible packaging batteries with different sample data lengths of not less than 25mm, a steel semi-cylinder with a diameter of 25mm should be placed

Extruded on a wide surface of the battery, the vertical axis of the half cylinder crosses the center of the wide surface and is perpendicular to the direction of the battery pole lug. The length of the semi-cylinder should be greater than the length of the extruded battery

Size, extrusion pressure reach the extrusion pressure corresponding to the width of the flexible packaging battery in Table 10, and then cut off.

The placement of batteries in the test is shown in Figure 4. A squeeze test was performed on one sample. During the extrusion process, the time interval between the extrusion reaching the cutoff state and the extrusion device stopping should not exceed 100ms.

Heavy Impact

After the battery is fully charged in accordance with the test method specified in 4.5.1, the battery is placed on the surface of the platform and a metal rod with a diameter of 15.8mm and 0.2mm is placed horizontally on the center surface of the battery. The surface of the battery was hit with a metal rod with a weight of 9.1ke01kg from a height of 610mm±25mm and observed for 6 hours.

It is required that the vertical axis of the cylindrical battery should be parallel to the surface of the heavy object during the impact impact test, the metal bar should be perpendicular to the vertical axis of the battery and parallel to the impact surface as far as possible, and the square battery should only carry out the culture impact strength test on the wide surface. The button battery technology performs an analytical impact test by traversing a metal rod through a battery material surface treatment center. Only one large impact test is performed on one sample.

The battery must not catch fire or explode.

Note: This article does not apply to flexible packaging batteries.

Heat Abuse

After charging the battery according to the test method specified in 451, place the battery in the test chamber. The laboratory is heated at a rate of 5 ° C/MIN + 2 ° C/MIN, and the constant temperature is 130 ° C + 2 ° C for 30min.

The battery should not catch fire or explode.

Combustion Injection

After the battery enterprise is fully charged according to the test and research method specified in 4.5.1, the battery is placed on the steel wire mesh of the test equipment. The test equipment is shown in C2 in Appendix C. If such a slip occurs repeatedly during the development of a test, a single wire can be used to secure the battery sample to the wire mesh: if no such problem does not occur, there is no need to use the bundled battery. Heat the battery with a flame, and stop heating when there are three different situations with the following analysis:

a) Battery explosion;

b) The battery is completely burned;

C) Continue heating for 30 minutes, but the battery does not catch fire or explode.

After testing, components (except dust products) or the entire battery should not penetrate the aluminum mesh.