A hydrocarbon/Nafion bilayer membrane is fabricated using a three-dimensionally interlocked interfacial layer for improved cycling durability of VRFBs.

In this work, we present a 16 μm-thick Nafion-filled porous membrane for Zn/Br redox flow batteries (ZBBs). By using molecular dynamics simulation and dynamic light scattering analysis, we rationally design Nafion solution for Nafion impregnation into a porous polypropylene (PP) separator. A void-free Nafion/PP membrane is successfully fabricated by using NMP as a solvent for the Nafion solution. The resulting membrane shows a smaller area specific resistance in comparison with 600 μm-thick, commercial SF-600 porous membrane. Due to its dense morphology, Br2 diffusivity of the Nafion/PP membrane is two orders of magnitude lower than that of SF-600, resulting in a comparable Br2 crossover in spite of 37.5 times smaller membrane thickness. As a result, the ZBB based on the Nafion/PP membrane exhibits a higher energy efficiency, demonstrating that ion exchange membrane can outperform the conventional porous membrane by reducing the membrane thickness with inexpensive porous substrate.

No abstract

Spatial confinement of sulfur in porous carbons has been one of the major approaches to address the polysulfide (PS) shuttle problem of lithium‐sulfur (Li−S) batteries. Among them, microporous carbon can effectively confine sulfur inside pores, however, it shows low active material utilization due to pore blockage by discharge products. To address this issue, in this work, zeolite‐templated carbons (ZTCs) with high surface area and electronic conductivity are used as host material for Li−S battery and their particle size is varied to explore better performances. With decrease of the particle size from 400 to 20 nm, initial sulfur utilization is enhanced from 20.7 to 71.6 %. The smaller ZTC particle delivers a high capacity retention of 94.6 % at 200 cycles. From electrochemical and spectroscopic analyses, it is demonstrated that smaller ZTC particles lead to easier penetration of Li ions inside the pores, resulting in more uniform Li2S deposition on the entire surface of the micropores. Due to its excellent size‐tunability and well‐defined pore structure, ZTC can be an effective sulfur host for the design of high‐performance Li−S batteries.