Three reasons for the combustion or explosion of lithium ion batteries
Indicate the source and the capital of the battery
Lithium ion secondary battery has become one of the main power sources of portable electronic products such as mobile communication, notebook computers and so on because of its high specific energy, high working voltage, small volume and light weight. However, due to improper use of lithium ion battery in charge and discharge process, there will be an explosion risk. Especially under abuse conditions, such as heat, overcharge, short circuit, vibration, extrusion, etc., the battery will burn, explode and even be injured. Therefore, it is of great significance to study the explosion mechanism of lithium ion batteries for the improvement of the safety of lithium ion batteries.
Looking at the picture of the battery explosion in the above picture, the battery network industry people analyzed 3 possibilities for the combustion or explosion of lithium ion batteries, the main three.
1. When a lithium ion battery is heated, the reaction inside the battery is like a reaction chain, and each reaction promotes each other in turn. The first is the SEI film emits heating the battery anode and the solvent reaction prompted to emit more heat, resulting in negative and adhesive reaction, solvent decomposition, and then start the positive thermal decomposition reaction, heat and gas, resulting in battery combustion or explosion.
In two, lithium ion batteries the early part of the electrical energy is converted into heat current through the battery, also produced a part of ohmic heat, but the surface temperature of the battery is rising very slowly; when the battery reaches full state, continue to intercalation by lithium ion into lithium metal deposited on the cathode surface, the solvent is oxidation (release of oxidation reaction caused by overcharge solvent heat is much higher than that of reversible state lithium ion and solvent heat) heating the heat released from the battery; with the battery temperature, lithium metal and solvent, lithium and carbon reaction solvent reaction occurred, heat control, accompanied by the decomposition of solvent binder, with lithium metal reaction.
Three, the damage caused by short circuit, acupuncture and impact on the lithium ion battery is approximately the same. When a short circuit current to produce a lot of heat through the instant heating battery battery, the battery temperature rises to cathode decomposition temperature, and cause the battery to heat runaway positive thermal decomposition; acupuncture is fast, cause local short circuit at the site of acupuncture and generate a lot of heat, the internal temperature of the battery is increased to thermal decomposition temperature; when the lithium ion battery impact, electrode over voltage loss of heat, and the negative reaction to the solvent, the heat released and further heat the battery, to positive thermal decomposition reaction, cause heat control.