All lithium ion batteries, whether in the past or in recent years, including lithium polymer batteries, lithium iron phosphate batteries and so on, are very afraid of internal battery short circuit, external battery short circuit, overcharge these situations.
Because, the chemical properties of lithium is very active, easy to burn, when the battery discharge, charging, the battery will continue to heat up, the gas expansion generated in the activation process, increase the battery pressure, pressure to a certain extent, such as shell scars, that will break, cause leakage, fire, and even explosion.
In order to mitigate the danger of lithium-ion batteries, technicians add ingredients that can inhibit lithium activity (such as cobalt, manganese, iron, etc.), but these do not fundamentally change the danger of lithium-ion batteries.
When overcharge and short circuit occur in common lithium-ion batteries, temperature rise, decomposition of cathode materials, oxidation of cathode and electrolyte materials and other phenomena may occur in the battery, which leads to gas expansion and increase of internal pressure of the battery. When the pressure reaches a certain level, explosion may occur. Lithium-ion polymer batteries, by using colloidal electrolytes, do not produce large amounts of gas as the liquid boils, thereby eliminating the possibility of violent explosions.
Most of the domestic polymer batteries are just soft pack batteries, using aluminum plastic film as the shell, but the electrolyte has not changed. This kind of battery can also be thin, its low temperature discharge characteristics are better than polymer batteries, and the material energy density is basically the same as liquid lithium batteries and ordinary polymer batteries, but because of the use of aluminum plastic film, it is lighter than ordinary liquid lithium batteries. On the safety side, when the liquid just boils, the aluminum film of the flexible battery will naturally bulge or break, and it will not explode.
It should be noted that the new battery can still burn or expand and crack, so safety is not foolproof.
Therefore, we must pay attention to safety when using various lithium ion batteries.