The Importance of Lithium ion Battery Safety

With the popularity of mobile phones, digital products, and electric vehicles, lithium-ion batteries are playing an increasingly important role in people's lives. Low energy density, limited cycle life, and other usage issues are often criticized by people. However, compared to these issues, battery safety is the focus of people's attention. In recent years, accidents caused by battery safety issues have been numerous, and the consequences of many problems are shocking, such as the shocking Boeing that shocked the industry787The "Dream" technology lithium battery fire incident, andSamsung Galaxy Note 7The widespread battery fire and explosion incidents have once again sounded the alarm for the safety of lithium-ion batteries.

Generally speaking, safety issues with lithium-ion batteries manifest as combustion or even explosion, and the root cause of these problems lies in the thermal runaway inside the battery. In addition, some external factors can also lead to safety issues. The occurrence of internal thermal runaway is closely related to the electrolyte of lithium-ion batteries.

The electrolyte of lithium-ion batteries is a mixed solution of lithium salt and organic solvents. The commercially available lithium salt is lithium hexafluorophosphate, which is prone to thermal decomposition at high temperatures and undergoes thermochemical reactions with trace amounts of water and organic solvents, reducing the thermal stability of the electrolyte. The organic solvent in the electrolyte is carbonate, which has a low boiling point and flash point and is prone to release lithium salts at high temperaturesPF5The reaction is easily oxidized.