Ahn Hee-joon, a professor from the Department of Organic and Nano System Engineering at Hanyang University, and his team developed an cathode material that can charge aqueous zinc ion batteries within 30 seconds. Aqueous zinc ion batteries are considered safe next-generation batteries that can be worn on the body as they use water as electrolytes and are inexplosive.

Most energy storage mediums, including electric vehicles, use lithium-ion batteries with high energy conversion efficiency. However, with the soaring demand for lithium, the safety issues such as fire, explosion, and toxicity have been pointed out.

As a result, the development of "aqueous zinc ion batteries" was carried out to prevent explosion or fire while enlarging storage capacity, and improving the charging speed, life and safety. However, the low conductivity, life and stability of vanadium oxides, which are used as cathode materials for aqueous zinc-ion batteries, were pointed out as disadvantages in addition to its complex synthesis processes.

To improve these disadvantages, Ahn's team developed vanadate nanofibers with high electrical conductivity by inducing the "polyoxometalate reaction" of vanadium oxides with high electrical conductivity.

In addition, they succeeded in developing the world's first technology to insert conductive polymer monomers into nanofibers and compounding them by interlayer polymerization reaction inside the inorganic crystal lattice.

The fiber-type nanocomposites developed in this way have higher electrical conductivity due to conductive polymers inserted into the crystal surface and maintain excellent capacity at 94% even after 1000  charges and discharges. 

In addition, the distance between crystal lattices of vanadate nanofibers increased by conductive polymer insertion makes it easy to remove and insert electrolyte ions during charging and discharging, which makes it possible to fully charge the aqueous zinc ion battery within 30 seconds.

The aqueous zinc ion batteries that Ahn's team developed can be used for flexible materials and battery safety as well as electrochemical properties, so they are expected to be widely used in wearable electronic devices that require both flexibility and safety.

The study, "Controlling Vanadate Nanofiber Interlayer via Intercalation with Conducting Polymers: Cathode Material Design for Rechargeable Aqueous Zinc Ion Batteries," was published in the monthly issue of Advanced Functional Materials (IF=18.808), a world-renowned materials science journal.

With Professor Ahn Hee-joon, various researchers including Lee Se-hun, Park Chang-yong, and Kim Ji-chang from the Institute of Nano Science and Technology, and Kim Hyung-seok and Jung Kyung-yoon Korea Institute of Science and Technology participated in the research.