CHE Hang-xin, GAO Yu-fei, YANG Jia-hui, HONG Song, HAO Lei-duan, XU Liang, Sana Taimoor, Alex W. Robertson, SUN Zhen-yu. Bismuth nanoparticles anchored on N-doped graphite felts to give stable and efficient iron-chromium redox flow batteries[J]. New Carbon Mater., 2024, 39(1): 131-141. DOI: 10.1016/S1872-5805(24)60837-1
Citation: CHE Hang-xin, GAO Yu-fei, YANG Jia-hui, HONG Song, HAO Lei-duan, XU Liang, Sana Taimoor, Alex W. Robertson, SUN Zhen-yu. Bismuth nanoparticles anchored on N-doped graphite felts to give stable and efficient iron-chromium redox flow batteries[J]. New Carbon Mater., 2024, 39(1): 131-141. DOI: 10.1016/S1872-5805(24)60837-1

Bismuth nanoparticles anchored on N-doped graphite felts to give stable and efficient iron-chromium redox flow batteries

  • Iron-chromium redox flow batteries (ICRFBs) use abundant and inexpensive chromium and iron as the active substances in the electrolyte and have great potential as a cost-effective and large-scale energy storage system. However, they are still plagued by several issues, such as the low electrochemical activity of Cr3+/Cr2+ and the occurrence of the undesired hydrogen evolution reaction (HER). We report the synthesis of amorphous bismuth (Bi) nanoparticles (NPs) immobilized on N-doped graphite felts (GFs) by a combined self-polymerization and wet-chemistry reduction strategy followed by annealing, which are used as the negative electrodes for ICRFBs. The resulting Bi NPs react with H+ to form intermediates and greatly inhibit the parasitic HER. In addition, the combined effect of Bi and N dopants on the surface of GF dramatically increases the electrochemical activity of Fe2+/Fe3+ and Cr3+/Cr2+, reduces the charge transfer resistance, and increases the mass transfer rate compared to plain GF. At the optimum Bi/N ratio of 2, a high coulombic efficiency of up to 97.7% is maintained even for 25 cycles at different current densities, the energy efficiency reaches 85.8% at 60.0 mA cm−2, exceeding many other reported materials, and the capacity reaches 862.7 mAh L−1 after 100 cycles, which is about 5.3 times that of bare GF.
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