Ali Muhammad, Hussain Hamid, Ali Moazzam, Aman Samia, Yang Weiwei, Ali Zeeshan, Li Lei, Jiang Yinzhu, Yousaf Muhammad
School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
Future Science Research Institute, ZJU Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 311215, China.
Adv Sci (Weinh). 2025 Jul 11:e03693. doi: 10.1002/advs.202503693.
Uncontrolled sodium-ion (Na) transport, fragile solid electrolyte interphase (SEI) layers, in and sluggish Na desolvation using conventional separators drive dendrite growth, posing critical challenges to the development of sodium metal batteries (SMBs). Porous materials with tunable Na transport pathways offer promise; however, simultaneously enhancing Na kinetics, promoting NaF-rich SEI formation, and lowering desolvation energy barriers remains a critical challenge. Herein, a trifunctional halogenated covalent organic framework (COF) integrated into a polypropylene (PP) separator (COF-F@PP) is designed to address these issues. The COF-F@PP separator features positively charged sites to anchor PF anions and facilitate desolvation of NaPF, and in-situ release of fluorine ions from halogenated COF promotes the formation of a robust NaF-rich SEI layer. Additionally, its high-porosity structure enables uniform Na transport. Theoretical simulation demonstrates that the COF-F@PP separator improves desolvation dynamics, ensures uniform Na flux distribution, and mitigates local electric field concentration, resulting in smooth and dendrite-free deposition. Consequently, a high Coulombic efficiency (99.2%), excellent ionic conductivity (1.13 mS cm), and stable cycling for over 1000 h at 3 mA cm are achieved. In Na||NVP full cells, COF-F@PP separator delivers an initial discharge capacity of 83.51 mAh g at 50 C and retains 88.42% of its capacity after 10 000 cycles.
不受控制的钠离子（Na）传输、脆弱的固体电解质界面（SEI）层以及使用传统隔膜时缓慢的Na去溶剂化过程会驱动枝晶生长，这对钠金属电池（SMB）的发展构成了严峻挑战。具有可调Na传输路径的多孔材料展现出了前景；然而，同时增强Na动力学、促进富含NaF的SEI形成以及降低去溶剂化能垒仍然是一项严峻挑战。在此，一种集成到聚丙烯（PP）隔膜中的三功能卤化共价有机框架（COF）（COF-F@PP）被设计用于解决这些问题。COF-F@PP隔膜具有带正电的位点以锚定PF 阴离子并促进NaPF的去溶剂化，并且卤化COF中氟离子的原位释放促进了坚固的富含NaF的SEI层的形成。此外，其高孔隙率结构能够实现均匀的Na传输。理论模拟表明，COF-F@PP隔膜改善了去溶剂化动力学，确保了均匀的Na通量分布，并减轻了局部电场集中，从而实现了平滑且无枝晶的沉积。因此，实现了高库仑效率（99.2%）、优异的离子电导率（1.13 mS cm）以及在3 mA cm下超过1000小时的稳定循环。在Na||NVP全电池中，COF-F@PP隔膜在50 C时的初始放电容量为83.51 mAh g，在10000次循环后仍保留其容量的88.42%。
