Flame-retardant polybenzimidazole-based composite separator for enhanced high-temperature performance and fire safety of lithium-ion batteries
image: Schematic illustration of synthesis process and SEM characterization of separators
Credit: Wanqing Li, Yukun Cao, Xiangfei Ren, Ruyi Yang, Yongchun Kan & Yuan Hu.
Researchers from the University of Science and Technology of China have developed a new flame-retardant polybenzimidazole-based composite separator that significantly improves the high-temperature performance and fire safety of lithium-ion batteries. This breakthrough, featured in the journal Frontiers in Energy, promises to address key safety challenges in high-energy-density battery applications.
The safety of lithium-ion batteries has been a pressing concern, particularly due to issues with the high flammability of commercial separators and non-uniform pore size distribution. These factors can lead to thermal runaway, posing risks in various applications. To tackle this, the research team focused on enhancing thermal stability and performance under high temperatures.
The study introduced a flame-retardant composite separator, P@HLi, which demonstrates superior thermal stability. This separator effectively suppresses the growth of lithium dendrites and enhances the high-temperature cycling performance of batteries. In practical tests, Li//Li symmetric batteries with P@HLi-20 separators maintained stable cycling for over 600 h at a low polarization potential, reducing dead lithium and dendrite formation. The LFP//Li and NCM811//Li cells equipped with these separators showed impressive initial discharge capacities and high-temperature cycling performance, with the LFP//Li cells retaining 98% of capacity after 100 cycles at 90 ℃. Furthermore, pouch cells with P@HLi-20 separators achieved significant reductions in peak heat and total heat release, underscoring their enhanced thermal safety.
The researchers employed a systematic approach, utilizing the P@HLi separator in various battery configurations to assess its electrochemical performance and safety characteristics under high-temperature conditions. The results were benchmarked against conventional Celgard separators, highlighting the considerable improvements offered by the new composite material.
This advancement holds significant implications for the battery industry, potentially leading to the development of safer, more reliable lithium-ion batteries suitable for high-demand applications such as high-energy-density battery systems. By mitigating risks associated with thermal runaway, the P@HLi separator could pave the way for broader adoption of lithium-ion technology in safety-critical environments.
The study was supported by the National Natural Science Foundation of China and the Key Research and Development Plan of Anhui Province. For a detailed understanding of this research, the full paper is available in Frontiers in Energy: https://journal.hep.com.cn/fie/EN/10.1007/s11708-025-1027-z. The team plans to explore further enhancements and applications of this technology in future studies.