Zhang Xiangyang, Ye Xiaolin, Huang Shaopei, Zhou Xuelong
Shenzhen Key Laboratory of New Lithium-ion Batteries and Mesoporous Materials, College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China.
ACS Appl Mater Interfaces. 2021 Aug 11;13(31):37111-37122. doi: 10.1021/acsami.1c08494. Epub 2021 Jul 28.
Elaborate nanoarchitectured solid/liquid interface design of felt electrodes is arguably the most effective pathway to promote the pore-level transport-reaction processes of redox flow batteries. Herein, we conceive a new type of nanocatalytic-layer-architectured graphite felt via introducing the vertically standing carbon nanosheet-confined Bi nanodots onto carbon fiber surfaces. The vertically standing carbon nanosheets construct a nanoporous layer with straight channels for vanadium ion shuttling, where highly dispersed Bi nanodots are stiffly confined to afford abundant active sites. The vanadium redox flow battery utilizing the rationally designed electrodes achieves an energy efficiency of 89% at 150 mA cm, which is substantially higher than those of raw felt (61%) and oxidized felt (77%). Also, the battery with the present electrode maintains an energy efficiency of over 73% even at 400 mA cm, showing the excellent capability of withstanding fast charging and discharging. The multiphysics simulation shows that the vertically standing architecture optimizes the vanadium ion accessibility to the solid/liquid interfaces and thus maximizes the catalytic activity. Moreover, the battery can sustain more than 1000 cycles without obvious efficiency decay, confirming the superb stability of the present electrode. These encouraging results indicate that engineering vertically standing structures with tailored compositions may open up new avenues for advancing the flow battery technology.
精心设计毡电极的纳米结构固/液界面，无疑是促进氧化还原液流电池孔级传输-反应过程的最有效途径。在此，我们通过将垂直排列的碳纳米片限制的铋纳米点引入碳纤维表面，构思了一种新型的纳米催化层结构石墨毡。垂直排列的碳纳米片构建了一个具有直通道的纳米多孔层，用于钒离子穿梭，高度分散的铋纳米点被牢固地限制在其中，以提供丰富的活性位点。使用合理设计电极的钒氧化还原液流电池在150 mA/cm²时实现了89%的能量效率，这大大高于原始毡（61%）和氧化毡（77%）的能量效率。此外，即使在400 mA/cm²时，采用本电极的电池仍保持超过73%的能量效率，显示出优异的快速充放电能力。多物理场模拟表明，垂直排列的结构优化了钒离子与固/液界面的接触，从而最大限度地提高了催化活性。此外，该电池可以承受超过1000次循环而没有明显的效率衰减，证实了本电极的卓越稳定性。这些令人鼓舞的结果表明，设计具有定制组成的垂直排列结构可能为推进液流电池技术开辟新的途径。
