Zinc-bromine flow battery operation

Zinc bromine flow batteries or Zinc bromine redux flow batteries (ZBFBs or ZBFRBs) are a type of rechargeable electrochemical energy storage system that relies on the redox reactions between zinc and bromine. Like all flow batteries, ZFBs are unique in that the electrolytes are not solid-state that store energy in metals.

While zinc bromine flow batteries offer a plethora of benefits, they do come with certain challenges. These include lower energy density compared to lithium-ion batteries, lower round-trip efficiency, and the need for periodic full discharges to prevent the formation of zinc dendrites, which could puncture the separator.

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.

Lee et al. demonstrated a non-flow zinc bromine battery without a membrane. The nitrogen (N)-doped microporous graphene felt (NGF) was used as the positive electrode (Figure 11A,B).

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.

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.