In particular, zinc-bromine flow batteries (ZBFBs) have attracted considerable interest due to the high theoretical energy density of up to 440 Wh kg −1 and use of low-cost and abundant active materials [10, 11].
A high performance and long cycle life neutral zinc-iron redox flow battery. The neutral Zn/Fe RFB shows excellent efficiencies and superior cycling stability over 2000 cycles. In the neutral electrolyte, bromide ions stabilize zinc ions via complexation interactions and improve the redox reversibility of Zn/Zn 2+.
Zinc-bromine flow batteries (ZBFBs) offer great potential for large-scale energy storage owing to the inherent high energy density and low cost. However, practical applications of this technology are hindered by low power density and short cycle life, mainly due to large polarization and non-uniform zinc deposition.
Neutral zinc–iron flow batteries (ZIFBs) remain attractive due to features of low cost, abundant reserves, and mild operating medium. However, the ZIFBs based on Fe (CN) 63– /Fe (CN) 64– catholyte suffer from Zn 2 Fe (CN) 6 precipitation due to the Zn 2+ crossover from the anolyte.
Even flow: A neutral zinc–iron flow battery with very low cost and high energy density is presented. By using highly soluble FeCl 2 /ZnBr 2 species, a charge energy density of 56.30 Wh L −1 can be achieved. DFT calculations demonstrated that glycine can combine with iron to suppress hydrolysis and crossover of Fe 3+ /Fe 2+.
The ultralow cost neutral Zn/Fe RFB shows great potential for large scale energy storage. Zinc-based flow batteries have attracted tremendous attention owing to their outstanding advantages of high theoretical gravimetric capacity, low electrochemical potential, rich abundance, and low cost of metallic zinc.