About the lithium ion battery safety analysis

Source: 2020 - 04 - 15 disguise hits: the safety of the lithium ion battery ion battery has high energy density, high output voltage, long cycle life and less environmental pollution, has been widely used in the field of microelectronics. At the same time, they are in the field of electric vehicles, military, space technology and so on also has a broad application prospect of [ 1 - 2] 。 However, lithium ion battery in the mankind at the same time also brought some safe hidden trouble. In recent years, lithium ion battery safety accidents occur frequently. For example, in 2006, apple, 苹果) And lenovo ( lenovo) Laptops for battery safety issues have been recalled; In 2008, Honda ( Honda) Hybrid cars on fire; 825 full electric buses for battery overheat on fire. As a result of these events, the safety of the lithium ion battery more and more get the attention of people. The lithium ion battery safety analysis of lithium ion battery safety problems can be attributed to two factors: one is the characteristics of lithium ion battery itself; Another kind is improper use or battery because of emergency. Lithium ion battery is a series of potential exothermic reaction, is the root of lithium ion battery safety problems. 1. The cause of the lithium ion battery itself the characteristics of lithium ion battery itself is the basic factor to determine the safety [ 3 - 4] :( 1) Due to their high energy density, lithium ion battery easily caused by thermal runaway unsafe behavior; ( 2) When lithium ion battery overcharge, due to the anode material of lithium ion, structure changes, has the strong ability of oxidation; Or the anode material and release oxygen directly, make the solvents have strong oxidation in electrolyte; The cathode surface of a solid electrolyte interface ( se I) The decomposition of membrane, as well as the precipitation from the cathode metal lithium and the reaction of the electrolyte, if these process release heat accumulation, may lead to thermal runaway. ( 3) Lithium ion battery electrolyte for organic solvent, main ingredients for carbonate, flash, low boiling point, in 4. 6 v or so easy to oxidation, if there is leakage, easy to cause the battery on fire, even burning explosion; ( 4) When lithium ion battery binder crystallization, easy to form copper dendritic and active substances, lead to internal short circuit batteries, bring safe hidden trouble. 2. Emergency or abuse of reason in some emergency cases, such as battery overcharge, acupuncture and moxibustion, extrusion, and high temperature environment, electrode and organic electrolyte to produce chemical reaction, such as S E I membrane decomposition, oxidation and reduction of organic electrolyte, anode decomposition, oxygen generated by the decomposition of the anode, further reaction with organic electrolyte. If these reactions produce large amounts of heat can't timely send out into the surrounding environment, can lead to thermal runaway, eventually lead to battery burning explosion.