A Long-life Redox Flow Battery
The Korea Advanced Institute of Science and Technology announced on Oct. 5 that its research team led by biochemical engineering professor Kim Hee-tak has developed a long-life redox flow battery (RFB) for use in large-scale energy storage systems (ESSs).
Most ESSs are based on inexpensive lithium-ion batteries. These days, after a series of fires, concerns are rising over the safety of those systems. In South Korea, 33 ESS fires were reported from 2017 to 2019 with 700 billion won in damage.
In this regard, researchers are focusing on RFBs using an aqueous electrolyte capable of preventing battery overheating. Especially, zinc-bromine RFBs are characterized by being inexpensive and higher in energy density than the other aqueous RFBs.
Although batteries of that type have been developed for use in ESSs since as early as the 1970s, commercialization has been limited due to the short life of the zinc electrode. This problem is because of dendrite formation during charge and discharge that leads to an internal short circuit.
The research team found out that self-agglomeration is the main cause of the zinc dendrite formation and the surface diffusion of zinc is suppressed and no dendrite formation occurs in certain carbon defect structures. The team applied a carbon electrode having a high-density defect structure to its zinc-bromine RFB and the battery showed a long life of more than 5,000 cycles at a charge and discharge current density of 100 mA/cm2, which is 30 times that of lithium-ion batteries.
Details of the research are available in the September edition of the Energy & Environmental Science journal.