UNIST Catalyst Provides Boost to Metal-Air Batteries

A research team, affiliated with Ulsan National Institute of Science and Technology (UNIST) has announced that a new catalyst that could boost metal-air batteries (MABs) performance, such as discharge and charge efficiency, was developed recently. MABs, which use oxygen from ambient air as recourses to store and convert energy, has received considerable attention for their potential use in electric vehicles (EVs) owing to their large storage capacity, lightweight, and affordability.

According to foreign media reports, a research team led by Professor Guntae Kim of the Institute of Energy and Chemical Engineering of the UNIST in South Korea has introduced a new type of composite catalyst to effectively improve the charge and discharge performance of metal-air batteries. It is a form of a very thin layer of metal oxide films deposited on a surface of perovskite catalysts, and thus the interface naturally formed between the two catalysts enhances the overall performance and stability of the new catalyzer.

metal-air batteries coatings and separators image

MAB is one of the lightest and most compact batteries, in which oxygen from the atmosphere reacts with metals to generate electricity. It is equipped with anodes made up of pure metals such as lithium, zinc, magnesium, and aluminum, and an air cathode that is connected to an inexhaustible source of air. Currently, MABs use noble metals such as platinum as catalyzers. Although the catalytic effect is good, the cost is too high, which hinders their commercial application. At the same time, as an alternative perovskite catalyst, it shows good catalytic performance, but the activation rate is low.

Professor Kim solved this issue by combining the two types of catalysts into a new composite catalyzer. In the charge-discharge reaction, each catalyzer showed excellent performance. A metal catalyzer (cobalt oxide), which performs well in charging, is deposited on a very thin layer on top of the manganese-based perovskite catalyst (LSM), which performs well in discharge. As a result, the synergistic effect of the two catalyzers became optimal when the deposition process was repeated 20 times.

renaissance of the iron-air battery image

Arim Seong, the first author of the study, said: "During the repeated deposition and oxidation cycles of atomic layer deposition (ALD) process, the Mn cations diffuse into Co3O4 from LSM, and therefore, the LSM-20-Co catalyzer is composed of LSM encapsulated with the self-reconstructed spinel interlayer (Co3O4/MnCo32O4/LSM), and this has enhanced the catalytic activity of the hybrid catalyzer." The research team said: "To the best of our knowledge, this is the first study to investigate the self-reconstructed interlayer induced by the in-situ cation diffusion during the ALD process for designing an efficient and stable bi-functional catalyst for alkaline zinc-air batteries."

Professor Kim said: "The new finding of UNIST provides the rational design strategy of self-reconstructed interlayer for efficient electro-catalyst. Therefore, this work can provide insight into the rational design strategy of metal oxide with perovskite materials to boost the performance of the metal-air batteries."