Lithium-ion secondary batteries have become one of the main power sources for portable electronic products such as mobile communication and notebook computers due to their high specific energy, high operating voltage, small size and light weight. However, lithium-ion batteries may explode due to improper use during charging and discharging. In particular, batteries may burn, explode or even be exposed to abuse (such as heat, overcharge, short circuit, vibration, extrusion, etc.) Injury and so on. Therefore, the study of lithium-ion battery explosion mechanism to improve the safety of lithium-ion battery has important significance. See the picture on the battery explosion picture, find the battery network industry analysis of lithium-ion battery combustion or explosion of the three possibilities, the following three.
First, when the lithium-ion battery is heated, the reaction within the battery such as a reaction chain, the mutual promotion of each other, in turn. The first is that the SEI membrane decomposes and releases heat to heat the battery to promote the reaction between the negative electrode and the solvent to emit more heat, which leads to the reaction between the negative electrode and the binder and the solvent to be decomposed. Then, the positive electrode begins to undergo the thermal decomposition reaction and emits a large amount of heat and gas , Eventually leading to the battery burning or explosion.
Second, lithium-ion battery charging in the early part of the electric current through the battery into heat energy, ohmic polarization also generates some heat, but the battery surface temperature rise is very slow; when the battery reaches full state, by the lithium-ion embedded The reaction becomes deposition of lithium metal on the surface of the negative electrode and the heat of the solvent is oxidized (the heat released by the oxidation reaction of the solvent caused by the overcharge is much higher than the heat released by the reaction between the lithium ions and the solvent in the reversible state) With the increase of the temperature of the battery, the lithium metal reacts with the solvent, the lithium intercalation reaction with the solvent occurs successively, and the heat is out of control. Simultaneously, the decomposition of the solvent and the reaction between the binder and the lithium metal occur.
Third, short circuit, acupuncture and impact on lithium-ion batteries caused by the same hazard. Short circuit, the current through the battery instantly produces a lot of heat, heat the battery, the battery temperature increases to the positive decomposition temperature, positive thermal decomposition and lead to the battery heat out of control; acupuncture at a very fast speed, resulting in the acupuncture part of the local Short circuit and generate a lot of heat, the battery internal temperature rise to positive thermal decomposition temperature; when the lithium-ion battery is hit, the electrode over-voltage loss of heat to promote the solvent and the negative reaction, the heat released further heat the battery , To promote the positive thermal decomposition reaction, leading to uncontrolled heat.