(Top row, left to right: Professor Hong John, Kookmin University; Professor Cha Pil Ryung, Kookmin University; Professor Hong Jin Pyo, Hanyang University. Bottom row, left to right: Master's student Kim Ye Won, Kookmin University; Master's student Kim Dae Hyun, Kookmin University; Dr. Kim Geun Woo, Korea University)

Professor Hong John's research team from the School of Materials Science & Engineering at Kookmin University announced the development of a crystal surface-controlled zinc metal electrode that dramatically improves the stability and lifespan of aqueous zinc-ion batteries, which are gaining attention as next-generation eco-friendly energy storage devices. This research was published in October 2025 in ‘Advanced Energy Materials’ (IF 26.0, top 2.5% in JCR), a globally authoritative journal in the field of energy materials. The research team focused on the issues of low energy density and structural deformation during charging and discharging in existing zinc foil-based electrodes, which can lead to deactivation of some electrodes. To overcome this, zinc metal powder was introduced; however, its large surface area and random crystal orientation accelerated hydrogen evolution reactions and uneven zinc growth.

To solve these problems, Professor Hong's team introduced a directional etching technique using trifluoroacetic acid (TFA) to the zinc powder electrode. They successfully selectively removed high-energy crystal planes from the zinc surface, exposing the stable (002) plane.

(Schematic of zinc powder electrode)

As a result, the TFA-treated zinc electrode (TFA@ZnMP) with a stepped structure maintained uniform current distribution while simultaneously suppressing hydrogen evolution and corrosion reactions, achieving outstanding interfacial stability. It demonstrated particularly stable long-term operation in symmetric cells and confirmed excellent capacity retention characteristics in pouch cells combined with a V2O5 cathode.

Kim Ye Won, a master's student at Kookmin University, stated, “It is very meaningful to have developed a technology that can significantly enhance the electrode stability of aqueous zinc-ion batteries through this research,” adding, “I hope to continue contributing to the advancement of eco-friendly battery research through the design of highly stable and efficient electrode structures.” This research was conducted under the leadership of Kim Ye Won, a master's student at Kookmin University, with participation from the research teams of Professors Hong John and Cha Pil Ryeong at Kookmin University (President Jeong Seung Ryul) and Professor Hong Jin Pyo at Hanyang University.