How does the cylindrical lithium electric explosion valve work in thermal discharge!

　　Thermal loss is the most serious safety accident in lithium ion batteries. Electric energy and chemistry stored inside lithium ion batteries can be released in large quantities in a short time, so that the temperature inside the lithium ion battery can even reach more than 900 ° C. At the same time A large amount of gas generated by the decomposition of active substances will cause the pressure inside the battery to rise sharply, and even cause the explosion of lithium ion batteries. In order to ensure the safety of lithium ion batteries, we usually design a explosion -proceed valve on the battery case. When the pressure is too high, we can be destroyed in time to release the pressure inside the battery to prevent the battery explosion during the heat out of control.

　　For the 18650 battery, the explosion -proof valve is designed in the upper cover of the battery. The explosion -proof valve also has the function of the circuit breaker. When the pressure of the battery increases to a certain degree, the explosion -proof valve moves the current circuit. When the pressure is further increased, the explosion -proof valve structure is destroyed, and the pressure inside the battery is released to prevent the battery from exploding. Previously, we mainly understood the design of the explosion -proof valve in principle. Because the structural design of the 18650 battery cover made it difficult for us to directly see the movement process of the explosion -proof valve during the heat out of control. Recently A) and Paul R. Shearing (Communication Author) The action process of the 18650 battery covering the 18650 battery of different manufacturers through a high -speed photography device was filmed, and it restored the entire process of the action of the 18650 battery explosion valve in thermal discharge. Essence

　　Related studies have shown that once the thermal discharge occurs, thermal discharge may spread to the entire 18650 battery within 2S. Therefore, in order to better observe the entire thermal output process, it is necessary to take more than 1,000 X -ray photos per second. The explosion of the battery is less than 0.01s, which requires a higher shooting speed. In order to meet this harsh requirement, Donal P. Finegan used the European synchronous radiation laboratory equipment to shoot the action process of 18650 battery explosion valve. The level of one million shots per second.

　　The test studies a total of 5 18650 batteries from LG, Panasonic, Samsung, and Sanyo and a 18650 battery with a new type of double explosion -proof valve (as shown in the table below). , LMO and LCO are mixed to verify the effects of different systems and battery structures on the safety of explosion -proceed valves.

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