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.
The zinc/bromine (Zn/Br2) flow battery is an attractive rechargeable system for grid-scale energy storage because of its inherent chemical simplicity, high degree of electrochemical reversibility at the electrodes, good energy density, and abundant low-cost materials.
Zinc–bromine rechargeable batteries are a promising candidate for stationary energy storage applications due to their non-flammable electrolyte, high cycle life, high energy density and low material cost. Different structures of ZBRBs have been proposed and developed over time, from static (non-flow) to flowing electrolytes.
Zinc-bromine (ZnBr) flow batteries exhibit relatively high energy density, deep discharge capability, and good reversibility (Table 2). The disadvantages include material corrosion, dendrite formation, and relatively low cycle efficiencies compared to traditional batteries, which can limit its applications [12, 35].
Static non-flow zinc–bromine batteries are rechargeable batteries that do not require flowing electrolytes and therefore do not need a complex flow system as shown in Fig. 1 a. Compared to current alternatives, this makes them more straightforward and more cost-effective, with lower maintenance requirements.
In the early stage of zinc–bromine batteries, electrodes were immersed in a non-flowing solution of zinc–bromide that was developed as a flowing electrolyte over time. Both the zinc–bromine static (non-flow) system and the flow system share the same electrochemistry, albeit with different features and limitations.