Advances in Lithium-Ion Battery Safety and Fire Prevention

With the rapid development of new energy technologies, lithium-ion batteries (LIBs) have become one of the core technologies in modern energy storage and electric mobility. With their advantages of high energy density, long life cycle, and light weight, LIBs are increasingly used in portable electronic devices, electric vehicles, and energy storage systems. However, the safety of LIBs, particularly related to their aging and the fires and explosions caused by thermal runaway (TR), is still one of the major challenges in their widespread application.

Firstly, changes in environmental factors, such as temperature, humidity, vibration, etc., have an impact on the internal ion migration and chemical reactions of LIBs, which can lead to the degradation of battery performance, as evidenced by the loss of capacity and voltage drop [1]. Secondly, due to the inherent instability of LIBs, the temperature inside the battery may rise sharply under abnormal conditions such as impact, overcharging, external heat sources, etc., triggering the TR phenomenon. TR not only accelerates the chemical reactions inside the battery and generates excessive temperature, but also may release large amounts of toxic gases, such as HF, CO, CO₂, etc. These gases have high toxicity and flammability, which may further trigger a fire or an explosion, resulting in serious casualties and property losses [2]. Therefore, in-depth studies on the decay laws of battery performance, TR mechanisms, and effective measures for preventing and controlling the risk of fires and explosions caused by TR in batteries have become a necessity in battery safety research.

To meet this challenge, in recent years, academia and industry have carried out a large number of studies on the safety of LIBs. These studies mainly focus on the following aspects: first, the performance degradation laws and aging mechanisms of LIBs in complex environments (e.g., temperature, humidity, vibration, etc.) [3,4]; second, the mechanisms of TR in LIBs, exploring the laws of temperature, pressure, and changes in the composition of the gases [5]; third, the design and optimization of battery materials and structure, such as through the use of flame-retardant electrolytes, the design of self-closing diaphragms, and other measures to enhance the intrinsic safety of batteries [6], while at the same time also developing efficient fire extinguishing technologies and gas elimination technologies to reduce heat propagation and the generation of harmful gases during thermal runaway [7,8]; and fourthly, the development of new types of battery management systems or early warning models to reduce the occurrence of TR through intelligent monitoring and control.

Despite some progress being made in this field, there are still a number of research gaps that need to be addressed urgently. Therefore, this Special Issue of the journal Batteries, “Advances in Lithium-Ion Battery Safety and Fire Prevention”, brings together 11 research papers on LIB safety, covering a wide range of areas from basic research to applied technologies. These studies provide valuable references for improving battery safety. Specifically, in terms of battery performance, Sabeel et al. (contribution 1) reviewed the effects of vibration environments on battery performance, pointing out that vibration causes damage to the battery structure and promotes dendrite formation, self-discharge, and lithium plating. In terms of TR of batteries, Jin et al. (contribution 2) investigated the evolution of TR in LIBs under different environmental pressures, and Sun et al. (contribution 3) investigated the effect of environmental pressure on the packaging forms of batteries (e.g., cylindrical and pouch commercial batteries), which provide guidance for the safe application of batteries under different environmental pressures. Hoelle et al. (contribution 4) designed a novel experimental setup to help the researchers to gain an in-depth understanding of the particle ejection process during TR. Mulder et al. (contribution 5) explored the electrical properties of TR gases, especially the flash-arc phenomenon that it may lead to. Mao et al. (contribution 6) summarized the flame behavior during TR in batteries, which provides a theoretical basis for further optimization of TR prevention and control techniques. In terms of enhancing the intrinsic safety of batteries, Santiago-Alonso et al. (contribution 7) and Al-Hamdani et al. (contribution 8) developed a new type of electrolyte to enhance the safety and efficiency of batteries, and Mao et al. (contribution 9) investigated the effect of different barrier materials on the propagation of TR in batteries and analyzed the barrier effects of different materials and their influencing factors, which provided fire prevention and the extinguishing of lithium batteries with theoretical support. In terms of monitoring and early warning technology, Pu et al. (contribution 10) studied an early warning method for TR in LIBs based on an electronic nose and a machine learning algorithm. Xie et al. (contribution 11) proposed a multi-parameter fusion early warning method based on a cloud model and Dempster–Shafer evidence theory, which effectively improves the accuracy of the TR risk assessment.

In summary, this Special Issue shows the latest research results in the field of LIB safety, covering research on battery performance, TR, intrinsic safety, fire prevention and extinguishing, monitoring and early warning systems, and other dimensions, providing valuable references to enhance the safety of LIBs. With the continuous improvement of battery energy density and the increasing diversification of application scenarios, LIB safety research is facing greater challenges. Future research will further explore the impact of complex environments on battery performance and TR, analyze the intrinsic evolution mechanisms, and develop new battery materials or fire extinguishing materials to ensure battery stability and safety. At the same time, combined with mechanical learning technology, the accuracy of TR warning systems for LIBs will be improved to cope with more complex safety issues.