The scarcity of wettability, insufficient active sites, and low surface area of graphite felt (GF) have long been suppressing the performance of vanadium redox flow batteries (VRFBs). Herein, an ultra-homogeneous multiple-dimensioned defect, including nano-scale etching and atomic-scale N, O co-doping, was used to modify GF by the molten salt system. NH₄Cl and KClO₃ were added simultaneously to the system to obtain porous N/O co-doped electrode (GF/ON), where KClO₃ was used to ultra-homogeneously etch, and O-functionalize electrode, and NH₄Cl was used as N dopant, respectively. GF/ON presents better electrochemical catalysis for VO²⁺/VO₂⁺ and V³⁺/V²⁺ reactions than only O-functionalized electrodes (GF/O) and GF. The enhanced electrochemical properties are attributed to an increase in active sites, surface area, and wettability, as well as the synergistic effect of N and O, which is also supported by the density functional theory calculations. Further, the cell using GF/ON shows higher discharge capacity, energy efficiency, and stability for cycling performance than the pristine cell at 140 mA cm⁻² for 200 cycles. Moreover, the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm⁻². Such an ultra-homogeneous etching with N and O co-doping through “boiling” molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.

中文翻译：

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全钒液流电池石墨毡电极多维缺陷工程

石墨毡（GF）润湿性的缺乏、活性位点不足和表面积低长期以来一直抑制着全钒氧化还原液流电池（VRFB）的性能。在此，采用超均匀多维缺陷，包括纳米级蚀刻和原子级N、O共掺杂，通过熔盐系统对GF进行改性。在体系中同时添加NH ₄ Cl和KClO ₃，得到多孔N/O共掺杂电极（GF/ON），其中KClO ₃用于超均匀刻蚀，并对电极进行O功能化，NH ₄ Cl分别用作N掺杂剂。与仅O-功能化电极(GF/O)和GF相比， GF/ON对VO ²⁺ /VO ₂ ⁺和V ³⁺ /V ²⁺反应具有更好的电化学催化作用。电化学性能的增强归因于活性位点、表面积和润湿性的增加，以及N和O的协同效应，这也得到了密度泛函理论计算的支持。此外，使用GF/ON的电池在140 mA cm ^-2 200个循环下表现出比原始电池更高的放电容量、能量效率和循环性能稳定性。^{此外，在260 mA cm -2}下，改进电池的能量效率比原始电池的55.2%提高了9.7% 。这种通过“沸腾”熔盐介质进行N和O共掺杂的超均匀蚀刻为制备优质VRFB电极提供了一种有效且具有实际应用潜力的方法。