Thermal conductive aramid nanofiber/surface-decorated alumina microsphere composite separator

• Published in: Polymer (Guilford) 2024-03, Vol.296, p.126793, Article 126793
• Main Authors: Chang, Chen, Wang, Xuyang, Zeng, Xingyan, Wen, Yingfeng, Nie, Hui, Chang, Li, Zhou, Xingping, Xie, Xiaolin, Ye, Lin, Mai, Yiu-Wing
• Format: Article
• Language: English
• Subjects: Composite separator; Electrocatalysis; Thermal conductivity
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2024.126793

The development of lithium-sulfur (Li–S) batteries is hindered by inhomogeneous Li plating and irreversible loss of active materials. In this work, a thermal conductive and electrocatalytic aramid nanofiber (ANF) composite separator containing surface-decorated alumina (Al2O3) microspheres is prepared through a simple filtration approach using ZnO nanosheets decorated Al2O3 microspheres (Al2O3@ZnO) as the thermal conductive filler and electrocatalyst. Compared with the separators fabricated by surface modification of commercial polyolefin separators, the as-prepared ANF/Al2O3@ZnO composite separator features homogeneous compositions and ensures uniform thermal distribution in both the through-plane and in-plane directions of the membrane. By rationally designing the structure of Al2O3@ZnO and adjusting the mass ratio of Al2O3@ZnO to ANF, excellent thermal conduction networks are formed by overlapping the ZnO nanosheets. Hence, the prepared ANF/Al2O3@ZnO composite separator possesses higher thermal conductivity than ANF/Al2O3 composite separator, which benefits uniform thermal distribution and homogeneous Li plating within the battery. Moreover, the electrocatalytic ZnO nanosheets catalyze the conversion of lithium polysulfides, efficiently inhibiting the shuttle effect and improving sulfur utilization. When subjected to a temperature gradient, the ANF/Al2O3@ZnO composite separator assembled cells display high initial capacity, low decay rate, and superb cycle stability. This novel composite separator integrates both thermal conductive and electrocatalytic functional components with the heat-resistant ANF matrix, offering a new design strategy of separator towards high-performance Li–S batteries. [Display omitted] •Aramid nanofiber/ZnO nanosheets decorated Al2O3 composite separator is fabricated.•Excellent thermal conductive pathways are formed by overlapping the ZnO nanosheets.•The shuttle effect of lithium polysulfides is inhibited by the electrocatalytic ZnO.•Uniform thermal distribution and even Li plating are achieved within Li–S battery.•The composite separator assembled cells display much improved battery performances.