KAIST Develops Lightweight and Flexible High-Performance Lithium-Organic Hybrid Battery

Professor Hyeryeong Byun (leftmost) at KAIST, who developed a lightweight and flexible high-performance lithium-organic hybrid battery, Dr. Vikramsingh, Dr. Jaewook Kim, and Professor Wooyeon Kim.

[Asia Economy Reporter Kim Bong-su] A lightweight, flexible, and high-performance lithium-organic hybrid battery has been developed.

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 20th that a joint research team led by Professors Byun Hye-ryeong and Kim Woo-yeon from the Department of Chemistry developed a lithium-organic hybrid battery with high cycle performance using a porous framework composed of organic molecules. The research team designed a large porous framework by linking molecules with a benzo-thiazole linker, which has an azo (N=N) group containing two nitrogen atoms with a double bond as a redox (oxidation-reduction) core. The large organic electrode is expected to replace current inorganic oxide-based electrodes and be utilized in the development of flexible and lightweight batteries. The research results were published in the May issue (Volume 11, Issue 17) of the international journal Advanced Energy Materials on June 6.

This study demonstrated that by designing organic molecules into a large framework, it is possible to improve chemical stability, insolubility, and electrical and ionic conductivity by controlling intermolecular interactions and electronic structures. Additionally, they developed an organic electrode capable of operating for about 1000 cycles even at a fast charge-discharge rate of once every six minutes.

The organic framework structure is a porous crystal formed by two-dimensional films created through covalent bonds of organic monomers, which grow three-dimensionally via pi-pi interactions. The design of the framework maximizes intermolecular interactions and stability while regularly forming pore channels of a few nanometers in size, facilitating smooth ion movement, making it a promising organic electrode material.

The organic framework used as an electrode for lithium-ion batteries consists of a redox core capable of electrochemical reactions with lithium ions and a linker that forms the porous framework. The joint research team used an azo group as the redox core, which can transfer two electrons (2e-) at a low potential.

The organic framework containing the benzo-thiazole linker exhibited simultaneous rapid two-electron transfer, unlike other materials, resulting in excellent charge-discharge rate characteristics and long cycle performance. This is because the bonding structure of the non-delocalized electrons in benzo-thiazole enhances the stability of the organic electrode. The research team directly demonstrated the reversible electrochemical reaction of the azo group in the electrode through real-time Raman spectroscopy observation.

Through density functional theory calculations, the research team proved that two lithium (Li) ions rapidly associate with the azo group. Experimentally, they confirmed that lithium ions can easily pass through the porous channels smaller than about 3 nanometers (nm) inside the benzo-thiazole-based azo organic framework, securing ionic conductivity.

Professor Byun Hye-ryeong stated, "The azo compound-based organic framework demonstrates high rate capability and long cycle performance of lithium-hybrid batteries, suggesting the practical potential of lightweight and flexible organic-based electrodes in the future." She added, "The design of the benzo-thiazole-based organic framework structure we developed is expected to provide flexible design options for various organic electrode developments going forward."

This content was produced with the assistance of AI translation services.