Affiliation:
1. School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150001 China
2. School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China
3. Department of Materials Science and Engineering National University of Singapore Singapore 117576 Singapore
Abstract
AbstractAqueous 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 (Li4[Fe(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 Li4[Fe(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.
Funder
National Natural Science Foundation of China