How to achieve internal short circuit protection for lithium ion batteries?

Due to the influence of material system and manufacturing process, lithium-ion batteries have the risk of internal short circuit. Although lithium-ion batteries have undergone rigorous aging and self-discharge screening at the factory, due to process failure and other unpredictable use factors, there is still a certain degree of failure probability that leads to an internal short circuit during use. For power cells, up to several hundred or even tens of thousands of lithium ion cells in their batteries greatly magnify the probability that the battery will occur within a short period of time. Due to the great energy contained in the power pack, the occurrence of internal short circuits can easily induce malignant accidents, resulting in casualties and property losses. TE's PPTC and MHP-TA series provide a possible solution to prevent malignant accidents in the event of an internal short circuit in a power cell.

For parallel lithium-ion power cell modules, when one or several cells are short, other cells in the cell module will discharge them. The energy of the battery pack will cause the temperature of the internal short cell to rise rapidly, easily inducing heat. Out of control, That eventually set the battery on fire and exploded.

Conventional temperature detection, when the battery is heated, can tell the IC to cut off the main loop, but it can not prevent the continuous discharge inside the parallel battery module. Since the main loop is cut off, all the energy of the battery module is concentrated on the internal short-circuit battery. Instead, it increases the chance of thermal runaway.

The ideal solution is to cut off the connection loop between the battery and other batteries in the module when it is found that the battery is short and heated. As shown in Figure 2, the TEPPTC or MHP-TA series products are assembled on a single cell. When an internal short circuit occurs, the TE protection device can effectively block the connection between the internal short circuit battery and other batteries in the module to prevent malignant accidents. For power batteries with a large number of monolithic cells, the internal resistance consistency of the cells and devices is required to be higher when matched. Because of its internal bimetallic structure, MHP-TA has a very good consistency of device resistance and can greatly meet the internal resistance of the battery. The requirements.

The system composition and actual road conditions of lithium-ion power cell are complex, and the protection of passive devices is indispensable.

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