Three-dimensional porous carbon materials have great importance as electrode materials for vanadium redox flow batteries due to electrochemical stability over a wide potential window and low cost. However, sluggish electrode kinetics toward vanadium redox reactions makes electrode treatment vital before its use in a vanadium redox flow battery. Researchers have used different routes to modify the graphite electrode surface. This article presents a very simple (and known) but tactical procedure to treat a graphite felt. The modified electrode possesses large surface area having well-developed uniform pore structures and abundant oxygen-rich surface functional groups (11.2%), which offers a significant reduction in peak separation potential and charge-transfer resistance with a noteworthy improvement in the peak current density and redox reaction reversibility compared to a bare graphite felt. The modified graphite felt electrode enables 14- and 19-fold improvements in exchange current toward VO²⁺/VO₂⁺ and V³⁺/V²⁺ redox reactions, respectively, than those of a bare graphite felt. The battery performance at 50 mA cm^–2 of current density displays energy efficiency (89%) and electrolyte utilization (89%) nearly 12 and 98%, respectively, higher than that of a bare graphite felt. The long-term performance (200 cycles) of the battery assured stable behavior of the modified electrode. Moreover, the present modified approach improves the peak power density by 3-fold compared to that of the bare graphite felt.

中文翻译：

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3D石墨毡作为钒氧化还原液流电池电极的战术表面改性，具有增强的电解质利用率和快速的反应动力学

三维多孔碳材料作为钒氧化还原液流电池的电极材料非常重要，这是因为其在宽的电位范围内的电化学稳定性和低成本。然而，针对钒氧化还原反应的缓慢的电极动力学使得电极处理在用于钒氧化还原液流电池之前至关重要。研究人员采用了不同的方法来修饰石墨电极的表面。本文介绍了一种非常简单（且已知）但战术性的方法来处理石墨毡。修饰电极的表面积大，具有发达的均匀孔结构和丰富的富氧表面官能团（11.2％），与裸露的石墨毡相比，它显着降低了峰分离电位和电荷转移电阻，并显着提高了峰电流密度和氧化还原反应可逆性。改良的石墨毡电极使对VO的交换电流提高了14倍和19倍与裸石墨毡相比，分别有²⁺ / VO ₂ ⁺和V ³⁺ / V ²⁺氧化还原反应。在电流密度为50 mA cm ^–2时的电池性能分别显示能量效率（89％）和电解质利用率（89％）分别接近裸石墨毡的12％和98％。电池的长期性能（200次循环）确保了修饰电极的稳定性能。而且，与裸石墨毡相比，本改进方法将峰值功率密度提高了三倍。