| Institution: | 1. School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001 China
These authors contributed equally to this work.;2. School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001 China;3. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150001 China;4. Department of Materials Science and Engineering, National University of Singapore, Singapore, 117576 Singapore |
| Abstract: | Aqueous redox flow batteries (ARFBs) are a promising technology for grid-scale energy storage, however, their commercial success relies on redox-active materials (RAM) with high electron storage capacity and cost competitiveness. Herein, a redox-active material lithium ferrocyanide (Li4Fe(CN)6]) is designed. Li+ ions not only greatly boost the solubility of Fe(CN)6]4− to 2.32 M at room temperature due to weak intermolecular interactions, but also improves the electrochemical performance of Fe(CN)6]4−/3−. By coupling with Zn, ZIRFBs were built, and the capacity of the batteries was as high as 61.64 Ah L−1 (pH-neutral) and 56.28 Ah L−1 (alkaline) at a Fe(CN)6]4− concentration of 2.30 M and 2.10 M. These represent unprecedentedly high Fe(CN)6]4− concentrations and battery energy densities reported to date. Moreover, benefiting from the low cost of Li4Fe(CN)6], the overall chemical cost of alkaline ZIRFB is as low as $11 per kWh, which is one-twentieth that of the state-of-the-art VFB ($211.54 per kWh). This work breaks through the limitations of traditional electrolyte composition optimization and will strongly promote the development of economical Fe(CN)6]4−/3−-based RFBs in the future. |
