Three mechanisms of safety problems caused by lithium batteries

    At present, in addition to requiring diaphragms to ensure absolute safety and high performance, they also require diaphragms to be lighter and thinner. In 2020, the thickness of lithium battery diaphragms will basically reach about 10um.

The security problems are mainly divided into the following three mechanisms:

1. Thermal shock. At high temperatures, the negative electrode SEI protective film, electrolyte, and positive electrode will be gradually decomposed, causing the internal temperature and pressure of the battery to increase, and finally the internal pressure and gas of the battery break through the outer shell, causing the exposed lithium metal of the negative electrode to contact the air to cause fire and burn, resulting in an explosion .

2. Overcharge. Too much lithium ions reach the negative electrode, and if it is too late to be embedded in the negative electrode, the lithium ions will be deposited on the surface of the negative electrode as lithium metal, forming lithium dendrites. Lithium dendrites are very easy to pierce the diaphragm and cause a short circuit inside the battery.

3. Inside the battery. External short-circuit or impact during use, needle sticks, etc., the voltage will drop instantaneously, the current will increase sharply, a large amount of energy will be consumed through the internal resistance and huge heat will be generated, the diaphragm will be melted, and the short-circuit area will continue to expand, triggering a vicious circle.