Professor Kyungwho Choi’s team (first author: Thien Trung Luu) of the School of Mechanical Engineering at Sungkyunkwan University, in collaboration with Professor Younghoon Lee’s team in the Department of Mechanical Engineering at Kyung Hee University, proposed a strategy to overcome the principal weakness of hydrogel electrodes—performance degradation in dry environments—through kosmotropic-ion embedding. By employing sulfate/sulfite ions (SO₄²⁻/SO₃²⁻) to simultaneously form internal crystalline domains and a surface charge-blocking layer (CBL), the team realized a triboelectric nanogenerator (TENG) technology that enhances both mechanical stability and triboelectric output even under arid conditions.

As a result, the TENG fabricated via the kosmotropic process achieved a more than threefold increase in power density and maintained stable output even at 700% strain. The researchers further demonstrated that the developed hydrogel sustains stable performance over 15,000 contact–separation cycles, and continues to operate reliably after 6 hours at 50 °C as well as after 30 days of storage at room temperature, thereby overcoming the rapid performance drop typically caused by water evaporation in hydrogel electrodes. They explain that these characteristics arise from ion concentration and the formation of localized polarization regions during partial dehydration, while the CBL suppresses charge leakage, enabling persistent response to mechanical stimuli.

Professor Choi, the lead investigator, stated, “Although hydrogel electrodes are renowned for their flexibility and stretchability, they clearly lose their properties in dry environments; the significance of this study lies in overcoming that limitation. Building on this technology, we will continue to develop high-output, highly stable energy-harvesting systems and pursue applications in wearable devices and sustainable energy systems.”

This research was supported by the 4th BK21 Future HRD Education and Research Center for Human-Centered Convergence Mechanical Solution and by the Korea government (MSIT). The results were published in Chemical Engineering Journal (JCR top 3%; IF 13.2) in August 2025

Title: Kosmotropic ions embedded hydrogel for significantly enhancing deformability and performance of iontronic triboelectric nanogenerators

Journal: Chemical Engineering Journal

DOI: https://doi.org/10.1016/j.cej.2025.167062