Highly Active Electrode With Efficiently Added Surface Oxygen Groups for a Vanadium Redox Flow Battery
Highly Active Electrode With Efficiently Added Surface Oxygen Groups for a Vanadium Redox Flow Battery
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DOI：
10.1115/1.4044959
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发表时间：
2019-09
影响因子：
2.5
通讯作者：
H. Ishitobi;S. Sugawara;Kosuke Oba;T. Hirano;Honoka Doki;Y. Handa;Yuma Sato;Shunya Yamamoto;N. Nakagawa
中科院分区：
文献类型：
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作者：
H. Ishitobi;S. Sugawara;Kosuke Oba;T. Hirano;Honoka Doki;Y. Handa;Yuma Sato;Shunya Yamamoto;N. Nakagawa
钒氧化还原液流电池的商业化需要通过较低的动阻输出更高的功率。在这项研究中，我们重点研究了碳纸作为电极材料的空气氧化条件，以降低动力学阻力。空气氧化被认为是由于碳纤维的氧化而影响表面氧基团的数量，例如苯酚型羟基。表面氧基团可以对应于充放电反应的活性中心。我们用程序升温脱附的方法定量地评估了表面氧基团的数量。此外，我们还测量了碳纸的双电层电容，它可以反映碳纤维的表面积。研究了电极的单电池性能，即电流-电压曲线和充放电曲线。空气氧化碳纸在5 0 0℃热处理3h(质量比原始样品减少8.4%)，在本研究中使用薄电极材料显示出最高的功率密度(96 0 mW cm−2)(约0.2 mm/张)。空气氧化促进了负半反应的发生。这一结果可以通过增加苯酚基团的数量来降低动力学阻力来解释，并且这种功率输出与使用商业碳纸和标准流场的钒氧化还原液流电池相比相对较高。
Higher power output by a lower kinetic resistance of the vanadium redox flow battery is needed for its commercialization. In this study, we focused on the air oxidation conditions of carbon paper, which is the electrode material, to reduce the kinetic resistance. The air oxidation is considered to affect the number of surface oxygen groups such as the phenol-type hydroxyl group due to oxidation of the carbon fiber. The surface oxygen groups may correspond to the active sites for the charge/discharge reaction. We quantitatively evaluated the number of surface oxygen groups by temperature-programmed desorption. In addition, we measured the double-layer capacitances of the carbon papers, which may reflect the surface area of the carbon fiber. The single-cell performances, i.e., current–voltage curves and charge–discharge profile, of the electrodes were studied. The air oxidized carbon paper, heat-treated at 500 °C for 3 h (8.4% mass decrease from the pristine sample), showed the highest power density (960 mW cm−2) in this study with thin electrode material (ca., 0.2 mm for one sheet). The negative half-reaction was enhanced by air oxidation. This result could be explained by the reduction of the kinetic resistance by increasing the number of phenol groups, and this power output was relatively high as the vanadium redox flow battery by using a commercial carbon paper and the standard flow field.