While the public energy demand is rising, depletion of fossil fuel reserves is a huge concern. Considerable attention has been devoted to the use of renewable clean energy to support the modern society. The National Science and Technology Council (NSTC) has been deeply involved in the energy issues for a long time, em-phasizing the development of fundamental research and international collabora-tion. With the support of NSTC research project and the Taiwan-Germany Lithium Battery International Cooperation project, Professor Jeng-Kuei Chang’s lab at De-partment of Materials Science and Engineering of National Yang Ming Chiao Tung University (NYCU) has worked in the field of energy storage materials for more than 12 years and has attained many noteworthy achievements. For examples, a high-safety ionic liquid electrolyte with low flammability and high thermal stability has been developed for lithium batteries. The research results are implemented in several industry-university collaboration projects. Both sides currently work to-gether to promote the technology transfer in industrial applications.
Among various kinds of energy storage batteries, lithium batteries have sev-eral advantages such as high energy density, high power density, low self-discharge rate, and high charge-discharge Coulombic efficiency. Although lithium batteries have above advantages, they also face several problems and challenges. A major thing is the safety issue, which is caused by the thermal runaway of lithi-um batteries with flammable carbonate electrolyte. This kind of traditional elec-trolyte is highly volatile and thermally unstable, causing the fire and explosion threats. Moreover, the insufficient electrochemical stability window of the car-bonate electrolyte restricts the cell voltage. The high-voltage-induced instability and decomposition can increase the safety risk and accelerate the battery perfor-mance deterioration.
To address above issues, Professor Chang's group at NYCU developed a series of ionic liquid electrolyte. The ionic liquid electrolyte is a key component in a bat-tery and plays a crucial role in determining the charge-discharge performance and even battery safety properties. Ionic liquids are molten salts composed of anions and cations and thus have intrinsic ionic conductivity. Ionic liquids are a promising type of electrolyte due to their wide electrochemical stability window, high ther-mal stability, low volatility, non-flammability, and environmental friendliness. For many years, Professor Chang's lab has been actively involved in the research and development of ionic liquid electrolytes. They have made distinctive advance-ments in the design of ionic liquid anion and cation structures, formulation of lith-ium salts, and the incorporation of co-solvents and additives. Chang's lab is re-garded as one of the top research groups in the world for developing ionic liquid electrolytes. The ionic liquid electrolyte developed by Prof. Chang’s lab has the fol-lowing highlights and application benefits: (1) The electrolyte has a wide electro-chemical stability window (> 5 V), which can increase the working voltage of the battery; (2) The high decomposition temperature of the electrolyte (> 400°C) can improve the thermal stability of the battery; (3) The electrolyte has low corrosivity toward electrode materials and current collectors, which increase the battery du-rability and reliability; (4) The battery safety can be improved by increasing the ex-othermic initiation temperature and reducing the exothermic heat output when the thermal runaway occurs; (5) The satisfactory charge-discharge performance and cycling stability of the battery can be achieved. Such properties are highly de-sired to meet the increasing demand for energy storage devices with high energy density, high stability, long cycle life, and good safety.
The aforementioned electrolyte technologies have successively carried out in-dustry-university collaboration with several companies and R&D institutions. Fur-ther, Professor Chang’s group has also continued to collaborate with top research teams at Massachusetts Institute of Technology (USA), Helmholtz Institute Ulm (Germany), and Kyushu University (Japan) to develop new and more cost-effective ionic liquid electrolyte. Actually, Professor Chang's research topics also involve the anode and cathode materials and solid-state electrolytes for lithium batteries, so-dium batteries, aluminum batteries, magnesium batteries, and supercapacitors. Professor Chang has published 270 SCI papers and 18 patents, and has conducted 10 technology transfer cases. Professor Chang aspires to devote his efforts to prac-tical applications of the academic research results and will continue to contribute to the energy-related communities.
Media Contact:
Yu-Hao Wang
Program Manager
Department of Engineering and Technologies
National Science and Technology Council
Tel: +886-2-27377526
yuhwang@nstc.gov.tw
