Scholars have made progress in the field of early warning of thermal runaway in lithium-ion batteries

Recently, Guo Tuan, a researcher at Jinan University, and Wang Qingsong, a researcher at the University of Science and Technology of China, and others have made important achievements in the field of early warning of lithium-ion battery thermal runaway optical fiber detection. The results were published online in Nature Communications.

With the increasing prominence of the global energy crisis, lithium-ion batteries represent high energy density, long endurance, mobile electrochemical energy storage equipment in the fields of smart electric vehicles and green energy storage power stations. However, frequent safety accidents such as battery fires and explosions seriously restrict its further development, and its common reason is that the battery is thermal runaway, which is described as “cancer” that threatens battery safety. The root cause of thermal runaway of the battery is a series of complex and interrelated “chain side reactions” inside the battery.

In-situ accurate decoupling of battery thermal runaway temperature and pressure changes to achieve early warning. Photo courtesy of the research team

How to “trace the internal causes of thermal runaway of batteries, clarify the coupling relationship between step-by-step reactions, reveal the dominant mechanism and kinetic law of thermal runaway, and move forward thermal runaway warning time window” is the core to fundamentally solve the safety problem of energy storage. However, due to the closed structure of the battery and the complex reaction mechanism inside, the accuracy and real-time detection of the core state parameters inside the battery cannot be guaranteed. The newly reported scientific instruments with “perspective” detection capabilities (such as neutron diffraction, X-ray diffraction, cryo-EM, etc.) cannot be applied to battery terminals due to their large size and high price. How to scientifically, timely and accurately predict battery safety hazards has become an international scientific problem in the field of battery safety.

In order to overcome this scientific problem, the research team proposed a multi-modal integrated optical fiber in-situ monitoring technology that can be implanted inside the battery, which realized the accurate analysis and early warning of the whole process of thermal runaway of commercial lithium batteries. The team designed and successfully developed a multi-modal integrated optical fiber sensor that can work normally in a high temperature and high pressure environment of 1000°C, realized the synchronous and accurate measurement of the internal temperature and pressure of the whole process of thermal runaway of the battery, overcame the problem of crosstalk between temperature and pressure signals in the extreme environment of thermal runaway, proposed a new method to decouple the heat generation and air pressure change rate of the battery, discovered the characteristic inflection point and common law that triggered the thermal runaway chain reaction of the battery, and realized the accurate discrimination of the microscopic “irreversible reaction” inside the battery.

This research work provides an early warning means for quickly cutting off the thermal runaway chain reaction of the battery, and provides a new idea for ensuring the operation of the battery in a safe range. (Source: China Science News Zhu Hanbin)

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