College of Materials Science and Engineering, Changsha University of Science & Technology, Changsha, 410114, P. R. China.
Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences (P. R. China).
Chem Asian J. 2020 Aug 3;15(15):2357-2363. doi: 10.1002/asia.202000140. Epub 2020 Apr 2.
Ion exchange membranes play a key role in all vanadium redox flow batteries (VRFBs). The mostly available commercial membrane for VRFBs is Nafion. However, its disadvantages, such as high cost and severe vanadium-ion permeation, become obstacles for large-scale energy storage. It is thus crucial to develop an efficient membrane with low permeability of vanadium ions and low cost to promote commercial applications of VRFBs. In this study, graphene oxide (GO) has been employed as an additive to the Nafion 212 matrix and a composite membrane named rN212/GO obtained. The thickness of rN212/GO has been reduced to only 41 μm (compared with 50 μm Nafion 212), which indicates directly lower cost. Meanwhile, rN212/GO shows lower permeability of vanadium ions and area-specific resistance compared to the Nafion 212 membrane due to the abundant oxygen-containing functional groups of GO additives. The VRFB cells with the rN212/GO membrane show higher Coulombic efficiencies and lower capacity decay than those of VRFB cells with the Nafion 212 membrane. Therefore, the cost-effective rN212/GO composite membrane is a promising alternative to suppress migration of vanadium ions across the membrane to set up VRFB cells with better performances.
离子交换膜在全钒氧化还原液流电池（VRFB）中起着关键作用。大多数可用的 VRFB 商业膜是 Nafion。然而，其缺点，如高成本和严重的钒离子渗透，成为大规模储能的障碍。因此，开发一种具有低钒离子渗透性和低成本的高效膜对于促进 VRFB 的商业应用至关重要。在这项研究中，氧化石墨烯（GO）已被用作 Nafion 212 基质的添加剂，并获得了一种名为 rN212/GO 的复合膜。rN212/GO 的厚度已减少到仅 41μm（与 50μm 的 Nafion 212 相比），这直接表明成本更低。同时，由于 GO 添加剂中含有丰富的含氧官能团，rN212/GO 与 Nafion 212 膜相比，具有更低的钒离子渗透性和比面积电阻。具有 rN212/GO 膜的 VRFB 电池的库仑效率更高，容量衰减更低，优于具有 Nafion 212 膜的 VRFB 电池。因此，具有成本效益的 rN212/GO 复合膜是一种有前途的替代方案，可以抑制钒离子穿过膜的迁移，从而构建具有更好性能的 VRFB 电池。
