Liu Zetong, Li Pingan, Hu Kangjia, Sun Hao, Li Rongxing, Yang Shanshan, Hu Xianluo
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Macromol Rapid Commun. 2025 Jan;46(2):e2400644. doi: 10.1002/marc.202400644. Epub 2024 Oct 14.
The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic-inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m-phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote "ion flow redistribution." The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19 µm-thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68 mS cm) and a high lithium-ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000 h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1 C and demonstrates impressive rate capability with a discharge capacity of 72.7 mAh g at 15 C.
商用聚烯烃隔膜的离子电导率欠佳，加剧了锂枝晶的无控制生长，导致锂金属电池性能恶化并带来安全隐患。为应对这一挑战，制备了一种新型有机-无机复合隔膜，以增强离子传输并有效抑制枝晶生长。这种隔膜的特点是具有热稳定、高度多孔的聚间苯二甲酰间苯二胺（PMIA）电纺膜，表面涂覆有超长羟基磷灰石（HAP）纳米线，可促进“离子流重新分布”。PMIA中的氮原子与HAP中的羟基之间的协同效应阻碍了阴离子传输，同时促进了高效的锂传导。此外，优化的单侧孔结构确保了离子的均匀传输。结果表明，19 µm厚的HAP/PMIA复合隔膜具有显著的离子电导率（0.68 mS cm）和较高的锂离子迁移数（0.51）。使用HAP/PMIA隔膜的锂对称电池表现出超过1000小时的寿命且极化较低，明显优于商用聚丙烯隔膜。此外，这种隔膜使LiFePO||Li电池在1 C下循环200次后仍能保持97.3%的容量，在15 C下放电容量为72.7 mAh g，展现出令人印象深刻的倍率性能。
