EVENTS 講演会

講演の題目 ： Chemistries in batteries and recent progresses on dual-ion batteries to increase power density

講師 ： Prof. Denis Yau Wai YU　（School of Energy and Environment, City University of Hong Kong）

講演の概要 ：
Batteries are ubiquitous and they are important components for storing energy in the sustainable world. In this lecture, we will first introduce the basic principles of a battery and discuss how different materials have been applied in battery systems throughout the 200+ year history, starting from the voltaic pile in 1800 to batteries we have nowadays. Then, we will go through some of the considerations in electrochemistry that allow lithium-ion batteries (LIB) to store large amount of energy and discuss about their applications.
In traditional LIB, Li ions are the charge carriers that are shuttled between the cathode and anode during charge and discharge. Because the cations have to travel through two interfaces, rate performance is limited. In the second half of lecture, we will introduce the use of anions to increase power of energy storage devices. Specifically, graphite can store anions such as PF6- and TFSI- with an operating potential of >4.5 V vs. Li/Li+, so it is possible to construction a dual-ion battery with simultaneous Li+ and PF6- reactions on the two electrodes. A dual-ion battery shows similar power characteristics as a supercapacitor but has higher energy density as charges are also stored in the active materials. We will discuss the factors affecting anion intercalation into graphite. In particular, electrolyte and the corresponding cathodic electrolyte interface are found to be critical to the stability of the electrode.