Yu Liwei, Yu Lihong, Wang Lie, Wang Lei, Qiu Xinping, Xi Jingyu
Institute of Green Chemistry and Energy, Graduate School at Shenzhen , Tsinghua University , Shenzhen 518055 , China.
School of Applied Chemistry and Biological Technology , Shenzhen Polytechnic , Shenzhen 518055 , China.
ACS Appl Mater Interfaces. 2019 Apr 10;11(14):13285-13294. doi: 10.1021/acsami.9b01632. Epub 2019 Mar 26.
The use of low-cost hydrocarbon membranes in vanadium flow batteries (VFBs) still remains a great challenge because of the strong oxidation of VO catholyte and rapid capacity fading. Here, we report a bilayer design strategy using an antioxidant and dense cross-linked sulfonated polyimide (cSPI) layer as a protective layer for a sulfonated poly(ether ether ketone) (SPEEK) membrane to shield catholyte degradation and mitigate electrolyte crossover. A scalable process is developed to fabricate an integrated bilayer SPEEK/cSPI membrane without delamination by spraying a SPEEK transition layer between the two polymers. The tightly bridged cSPI layer not only protects the SPEEK membrane from degradation but also enhances its mechanical strength, puncture resistance, and proton/vanadium-ion selectivity. When assembled in a VFB, the bilayer SPEEK/cSPI membrane demonstrates excellent rate performance under current densities of 40-200 mA cm, high adaptability at a wide temperature range of -15 to 60 °C, very slow capacity decay rate of 0.054% per cycle at 160 mA cm, and a maximum power density of 480 mW cm. These merits make the bilayer SPEEK/cSPI membrane a promising candidate for the next-generation VFB to achieve low-cost, high-rate, and all-climate energy storage.
由于钒氧化还原液流电池（VFBs）的钒离子正极电解液具有强氧化性且容量快速衰减，使用低成本的碳氢化合物膜仍然是一个巨大的挑战。在此，我们报道了一种双层设计策略，即使用抗氧化剂和致密交联的磺化聚酰亚胺（cSPI）层作为磺化聚醚醚酮（SPEEK）膜的保护层，以防止正极电解液降解并减轻电解液交叉渗透。通过在两种聚合物之间喷涂SPEEK过渡层，开发了一种可扩展的工艺来制备无分层的集成双层SPEEK/cSPI膜。紧密桥接的cSPI层不仅保护SPEEK膜不被降解，还增强了其机械强度、抗穿刺性以及质子/钒离子选择性。当组装在钒氧化还原液流电池中时，双层SPEEK/cSPI膜在40 - 200 mA cm的电流密度下表现出优异的倍率性能，在-15至60°C的宽温度范围内具有高适应性，在160 mA cm下每循环的容量衰减率非常缓慢，仅为0.054%，最大功率密度为480 mW cm。这些优点使双层SPEEK/cSPI膜成为下一代钒氧化还原液流电池实现低成本、高倍率和全气候储能的有前景的候选材料。
