In this work, we propose and develop a novel electrode made of aligned microscale carbon fibers interweaved with highly porous carbon nanofibers for vanadium redox flow batteries. Such a unique combination not only endows the electrode with a high permeability due to the reduced tortuosity and large macropores, but also an ultra-large specific surface area for redox reactions. As a result, a vanadium redox flow battery equipped with the newly-developed electrode is able to achieve an energy efficiency of 79.3% at the current density of 400 mA cm⁻², which is 9.9% higher than that with pure porous carbon nanofiber electrodes, and 14.1% higher than that with pure aligned fiber electrodes. More remarkably, the battery is capable of delivering a peak power density of as high as ∼1.9 W cm⁻² and a limiting current density of ∼5000 mA cm⁻². These results demonstrate that our strategy of interweaving porous carbon nanofibers between aligned microfibers effectively addresses the contradiction between permeability and surface area of porous electrodes, opening a new platform to fabricate high-performance electrodes for vanadium redox flow batteries.

在这项工作中，我们提出并开发了一种新型电极，由排列的微米级碳纤维与高度多孔的碳纳米纤维交织而成，用于钒氧化还原液流电池。这种独特的组合不仅使电极因弯曲度降低和大孔大而具有高渗透性，而且还具有用于氧化还原反应的超大比表面积。结果，配备新开发电极的钒氧化还原液流电池在400 mA cm ^-2的电流密度下能够实现79.3%的能量效率，比纯多孔碳纳米纤维电极高9.9% , 比纯排列的纤维电极高 14.1%。更值得注意的是，该电池能够提供高达 ~1.9 W cm ^-2的峰值功率密度和~5000 mA cm ^-2的极限电流密度。这些结果表明，我们在对齐的微纤维之间交织多孔碳纳米纤维的策略有效地解决了多孔电极的渗透性和表面积之间的矛盾，为制造用于钒氧化还原液流电池的高性能电极开辟了一个新平台。