Ding Lei, Yan Ning, Zhang Sihang, Xu Ruizhang, Wu Tong, Yang Feng, Cao Ya, Xiang Ming
Shandong Key Laboratory of Chemical Energy Storage and New Battery Technology, School of Chemistry and Chemical Engineering, Liaocheng University, No. 1, Hunan Road, Liaocheng 252000, China.
State Key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, Chengdu 610065, China.
ACS Appl Mater Interfaces. 2022 Feb 9;14(5):6714-6728. doi: 10.1021/acsami.1c22080. Epub 2022 Jan 28.
A shutdown-functionalized lithium-ion battery separator plays a pivotal role in preventing thermal runaway as cells experience electrical abuse, overcharge, and external short circuit. In this article, the trilayer separator endowed with shutdown function was fabricated by ingenious co-extrusion and bidirectional drawing based on the nano-AlO coating online construction during the β-iPP cavitation process. The middle layer composed of nano-AlO, polyethylene, and polypropylene offers a shutdown temperature of 130 °C, and skin polypropylene layers with nano-AlO coating hold optimized dimensional stability below the meltdown temperature. Crystal structure measurement and pore structure diagnosis disclose that nano-AlO thins coarse fibrils and makes the porous structure uniform. De-bonding of nano-AlO/β-iPP interfaces retains nano-AlO not only on the top surface of the separator but also on the pore intine to realize nano-AlO coating online construction, consequently strengthening tensile capacity, dimensional stability to heating, and electrolyte affinity. Electrochemical tests further disclose that nano-AlO coating stabilizes solid electrolyte interphase germination and heightens lithium-ion migration numbers, confining cell resistances and granting optimal high-rate performance and cycling ability. The proposed approach features simple technics, environment-friendly, continuous fabrication, and coating online construction, which can offer new ideas for the mass fabricating of the high-end separator.
具有热关闭功能的锂离子电池隔膜在电池遭受电滥用、过充电和外部短路时，对于防止热失控起着关键作用。在本文中，基于β-iPP空化过程中的纳米AlO涂层在线构建，通过巧妙的共挤出和双向拉伸制备了具有热关闭功能的三层隔膜。由纳米AlO、聚乙烯和聚丙烯组成的中间层热关闭温度为130℃，带有纳米AlO涂层的表层聚丙烯层在熔化温度以下具有优化的尺寸稳定性。晶体结构测量和孔结构诊断表明，纳米AlO细化了粗纤维并使多孔结构均匀化。纳米AlO/β-iPP界面的脱粘使纳米AlO不仅保留在隔膜的顶表面，还保留在孔内壁上，从而实现纳米AlO涂层在线构建，进而增强拉伸能力、热尺寸稳定性和电解质亲和性。电化学测试进一步表明，纳米AlO涂层稳定了固体电解质界面的形成并提高了锂离子迁移数，限制了电池电阻并赋予了最佳的高倍率性能和循环能力。所提出的方法工艺简单、环境友好、可连续制造且能在线构建涂层，可为高端隔膜的大规模制造提供新思路。
