Charge less, power more: Zinc-bromine battery tech hits record 10,000 charge cycles

In a significant advancement for energy storage technology, researchers have developed a novel electrode that effectively suppresses the harmful self-discharge phenomenon in flowless zinc-bromine batteries (FLZBBs).

The quest for clean, sustainable energy is on, and researchers are constantly innovating to improve energy storage systems. Lithium-ion batteries, while dominant, come with a major safety concern: flammable electrolytes.

FLZBBs offer a promising alternative with their non-flammable properties. However, a pesky issue called self-discharge has hampered their widespread adoption.

Now, a team of researchers at the Gwangju Institute of Science and Technology (GIST) in Korea have developed a revolutionary electrode that tackles this issue head-on, paving the way for a future powered by safe and efficient FLZBBs.

Addressing the challenges of FLZBB

FLZBBs boast several advantages over lithium-ion batteries . They’re safer, more cost-effective, and simpler in design. They work with a positive electrode, a negative electrode, a separator to keep them apart, and a gel-like electrolyte.

However, during operation, bromine ions generated at the positive electrode can migrate to the negative electrode, causing self-discharge and hindering performance. This has been a major hurdle for FLZBBs.

Professor Chanho Pak and his team, including Youngin Cho, the first author of the study, have developed a novel electrode that effectively puts a stop to self-discharge. It’s a nitrogen-doped mesoporous carbon-coated thick graphite felt (NMC/GF) electrode.

Their work paves the way for more stable and efficient FLZBBs.

Trapping the culprit: How the NMC/GF electrode works

The NMC/GF electrode is fabricated using a simple and cost-effective method. The researchers coat a standard graphite felt electrode with precursor materials, followed by drying and curing. The magic lies in the mesopores (tiny holes) created by the NMC coating.

These mesopores, along with strategically placed nitrogen sites, act like tiny cages, trapping the bromine ions and their complexes within the positive electrode. This effectively prevents them from reaching the negative electrode, stopping self-discharge in its tracks.

“This coating made the originally hydrophobic pristine GF electrodes ultrahydrophilic, improving interfacial contact with the electrolyte in the aqueous electrolyte and enhancing electrochemical performance,” Professor Pak elaborates on the benefits of the NMC/GF electrode.

“Additionally, it allowed the incorporation of abundant oxygen and nitrogen species, which improved bromine reaction speeds, further boosting performance.”

Unprecedented performance and long life

FLZBBs equipped with the NMC/GF electrode displayed exceptional efficiency, with a Coulombic efficiency of 96% and an energy efficiency of 76% at a specific current density. They also delivered a high areal capacity (the amount of charge stored per unit area) of 2 mAh cm-2. But that’s not all.

These batteries showed remarkable durability, lasting for over 10,000 charge and discharge cycles – a testament to their long-term stability. Plus, the use of a thick GF electrode can potentially bring down battery costs.

In the press release , Pak, excited about the future implications, said, “The development of FLZBB positive electrode, which maintains long-term operation over 10,000 cycles with high efficiencies, will accelerate the development of stable ESSs and eco-friendly energy conversion in the long term. Moreover, NMC/GF positive electrode can also be used for other aqueous batteries.”

This breakthrough has the potential to revolutionize the world of energy storage. With safer, more stable, and longer-lasting FLZBBs on the horizon, the path to a clean and sustainable energy future seems a little brighter.

The research was published in the Chemical Engineering Journal .