Parekh Mihit H, Oka Suyash, Lutkenhaus Jodie, Pol Vilas G
Davidson School of Chemical Engineering, Purdue University, West Lafayette 47907, Indiana, United States.
Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station 77843, Texas, United States.
ACS Appl Mater Interfaces. 2022 Jun 29;14(25):29176-29187. doi: 10.1021/acsami.2c04630. Epub 2022 Jun 14.
Ionically conducting, porous separator membranes with submicrometer size pores play an important role in governing the outcome of lithium-ion batteries (LIBs) in terms of life, safety, and effective transport of ions. Though the polyolefin membranes have dominated the commercial segment for the past few decades, to develop next-generation batteries with high-energy density, high capacity, and enhanced safety, there is a need to develop advanced separators with superior thermal stability, electrolyte interfacial capabilities, high melting temperature, and mechanical stability at elevated temperatures. Here, aramid nanofiber separators with enhanced mechanical and thermal stability dried at the critical point are processed and tested for mechanical strength, wettability, electrochemical performance, and thermal safety aspects in LIBs. These separators outperform Celgard polypropylene in all aspects such as delivering a high Young's modulus of 6.9 ± 1.1 GPa, and ultimate tensile strength of 170 ± 25 MPa. At 40 and 25 °C, stable 200 and 300 cycles with 10% and 11% capacity fade were obtained at 1 C rate, respectively. Multimode calorimetry, specially designed to study thermal safety aspects of LIB coin cells, demonstrates low exothermicity for critical-point-dried aramid nanofiber separators, and post-diagnosis illustrates preservation of structural integrity up to 300 °C, depicting possibilities of developing advanced safer, high-performance LIBs.
具有亚微米级孔径的离子导电多孔隔膜在锂离子电池（LIBs）的寿命、安全性和离子有效传输方面起着重要作用。尽管聚烯烃隔膜在过去几十年中一直主导着商业市场，但为了开发具有高能量密度、高容量和更高安全性的下一代电池，需要开发具有卓越热稳定性、电解质界面性能、高熔点温度以及高温下机械稳定性的先进隔膜。在此，对在临界点干燥的具有增强机械和热稳定性的芳纶纳米纤维隔膜进行了加工，并在锂离子电池的机械强度、润湿性、电化学性能和热安全性方面进行了测试。这些隔膜在所有方面都优于Celgard聚丙烯，例如具有6.9±1.1 GPa的高杨氏模量和170±25 MPa的极限拉伸强度。在40℃和25℃下，以1 C倍率分别获得了稳定的200次和300次循环，容量衰减分别为10%和11%。专门设计用于研究锂离子硬币电池热安全性的多模式量热法表明，临界点干燥的芳纶纳米纤维隔膜放热较低，诊断后表明在300℃下结构完整性得以保留，这表明开发先进、更安全、高性能锂离子电池具有可能性。
