China develops zinc-bromine flow battery with record stability after 700 cycles

Chinese researchers have developed a zinc-bromine flow battery that demonstrated record stability through a new mechanism based on two-electron bromine transfer, with a 5 kW prototype completing more than 700 cycles.

This latest Chinese breakthrough makes cheaper, longer-lasting giant batteries for storing solar and wind power more realistic, which could help cut your electricity bills and blackouts over time, which comes as electricity prices in some markets in Europe, including Germany, France and the UK, have increased significantly in recent years.

Professor Li Xianfeng from the Dalian Institute of Chemical Physics at the Chinese Academy of Sciences led development of the new battery version. The device showed record operational stability thanks to the new mechanism.

High corrosive activity of free bromine accumulating in the electrolyte during charging has been a major problem for traditional zinc-bromine batteries, New Science reported.

This element destroyed key battery components including electrodes, current collectors and membranes, shortening device lifespan and making their use in power grids unprofitable and risky.

Chinese researchers proposed adding special amine compounds to the electrolyte that bind bromine during battery operation.

Through reactions, the aggressive element converts to brominated amines, sharply reducing corrosion levels and improving safety. Free bromine concentration in the solution remains extremely low.

The approach eliminated the need for expensive fluorine-containing membranes previously required for such systems. Standard ion-exchange materials were used instead, reducing production costs and simplifying scaling of the technology.

The 5 kW flow battery prototype demonstrated high efficiency during testing. More than 700 stable operation cycles were recorded at current density of 40 mA/cm² and energy efficiency above 78%. Component analysis after testing revealed no signs of corrosion.

The development could form the basis for creating reliable, safe and economically effective energy storage systems, particularly relevant for integration into power grids and systems using renewable sources.