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An article to understand how lithium batteries are explosion-proof in high and low temperature tests
Date: Mar 21,2024 Views: 164
An article to understand how lithium batteries are explosion-proof in high and low temperature testsCurrently, lithium-ion batteries are widely used in mobile phones, laptops, electric vehicles, etc. However, lithium batteries are prone to "strike" when the temperature is too high or too low. In severe cases, they may explode or catch fire. When lithium-ion batteries are produced, they must undergo high and low temperature tests.
Lithium batteries need to be integrated with the charge and discharge system under various temperature conditions and changes of high temperature, low temperature, and temperature cycles to conduct overcharge, discharge, and short circuit tests at various temperatures to evaluate whether the Joule heat accumulation in the lithium battery during the test process will cause the battery to The temperature rise puts the internal materials of the battery at risk of thermal runaway. Once the battery experiences thermal runaway, it may explode and burn.
Since lithium ions have risks such as explosion and fire due to high temperature, the high and low temperature test chamber for temperature testing of lithium ions needs to be explosion-proof.
Ways to reduce the risk of explosions
1. Explosion-proof enclosure: Put components that may produce sparks, arcs and dangerous temperatures into the explosion-proof enclosure. The internal space of the equipment is separated from the surrounding environment through the explosion-proof enclosure.
2. Increase the protective gas pressure: Keep the pressure of the protective gas inside the equipment shell higher than the pressure of the surrounding explosive environment.
3. Filling sand: Fill the shell with sand or other powder materials with specified characteristics so that under the specified conditions of use, the arc or high temperature generated in the shell cannot ignite the surrounding explosive gas environment.
4. Sealing agent compound: The electrical components that may produce sparks, arcs or dangerous temperature parts that may cause the explosion of explosive mixtures are flow-sealed in (sealing agent compound) so that they cannot ignite the surrounding explosive mixture.
5. Immerse the equipment in protective liquid: Immerse the entire equipment or parts of the equipment in oil (protective liquid) so that it cannot ignite the explosive gas environment above the oil level or outside the shell.
6. Test monitoring: Set up a remote camera through the explosion-proof window for test monitoring, and detect the surface temperature of each battery. If the battery surface heats up abnormally, it is likely to explode, and the system will immediately activate the safety protection mechanism.
Assuming that when the battery explodes instantly, the high-strength inner furnace body can withstand the explosion force, and the standard explosion-proof holes will also vent the explosion pressure. The lithium battery special testing machine will detect its fire status, immediately extinguish the fire and cool down. After the fire is extinguished, use exhaust The exhaust mechanism discharges organic volatile gases and odorous gases in the box to ensure the cleanliness of the laboratory. It has passed lithium battery safety tests required by multiple international standards to avoid concerns such as explosion and combustion of lithium batteries.
Detailed explanation of commonly used explosion protection methods
Generally, safety accidents caused by batteries are caused by short circuits.
One method is to design a high and low temperature test chamber based on the size of the battery and the number of tests. For example, if the customer's battery size is 200 x 300 x 200mm, and two batteries are put in for testing each time, then we will put the battery The inner sheet of the high and low temperature test chamber should be reinforced and thickened, for example to 3mm or 5mm. In addition, 2-3 pressure relief holes should be opened in the battery high and low temperature test chamber. When the battery explodes, you only need to A few kilograms of force can open the pressure relief hole of the test box, quickly discharge the smoke and gas inside the box, and depressurize the test box very well.
Another method is to design the test chamber larger, because if the battery is placed in a small space, the power of its explosion will be much greater than if it is placed in a large space.
The battery explosion-proof high and low temperature chamber is used to test the safety of batteries for overcharge, overdischarge, and charge and discharge under various ambient temperatures. The test standards meet IEC60068-2-1:2007, GJB150.3-1986, and GB/T 31485. -2015.
1. Used for overcharging and over-discharging the battery: During the charge and discharge test, the battery is placed in an explosion-proof box. At the same time, in order to prevent the battery from exploding or burning and causing harm to the test personnel, it is made of high-quality stainless steel material with strong texture and good explosion-proof effect. The cabinet can also be customized according to testing requirements.
2. The structure of the lithium battery overcharge and overdischarge explosion-proof test chamber adopts a double-layer design: the internal SUS304 matte stainless steel plate is sprayed with Teflon insulation + the outer box is a high-quality cold-rolled steel plate with a thickness of ≥1.5MM, and the surface is treated with electrostatic powder paint. SUS has better high temperature resistance than iron plates. The inside of the test box is sprayed with Teflon, which can effectively prevent corrosion, insulate, flame retardant and is easy to clean.
3. Automatic fire extinguishing system of high and low temperature chamber: including CO2 carbon fire extinguishing device, water sprinkler device, electronic sensor transmitter, smoke alarm, drainage device, etc. The whole machine is equipped with automatic temperature control, timing system and dual over-temperature alarm device functions.
The battery explosion-proof high and low temperature test chamber is the key to having a certain temperature and impact resistance and being reusable. The outer box is made of high-quality cold-rolled steel plate with surface electrostatic powder paint treatment, which can prevent rust and achieve elegant and beautiful effects. Keming's test chamber can be customized according to testing requirements.
