S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Materials Science and Engineering (재료공학부) Journal Papers (저널논문_재료공학부)
Direct observation of redox mediator-assisted solution-phase discharging of Li-O-2 battery by liquid-phase transmission electron microscopy
Cited 42 time in Web of Science Cited 47 time in Scopus
- Issue Date
- Journal of the American Chemical Society, Vol.141 No.20, pp.8047-8052
- Li-O-2 battery is one of the important next-generation energy storage systems, as it can potentially offer the highest theoretical energy density among battery chemistries reported thus far. However, realization of its high discharge capacity still remains challenging and is hampered by the nature of how the discharge products are formed, causing premature passivation of the air electrode. Redox mediators are exploited to solve this problem, as they can promote the charge transfer from electrodes to the solution phase. The mechanistic understanding of the fundamental electrochemical reaction involving the redox mediators would aid in the further development of Li-O-2 batteries along with rational design of new redox mediators. Herein, we attempt to monitor the discharge reaction of a Li-O-2 battery in real time by liquid-phase transmission electron microscopy (TEM). Direct in situ TEM observation reveals the gradual growth of toroidal Li2O2 discharge product in the electrolyte with the redox mediator upon discharge. Moreover, quantitative analyses of the growth profiles elucidate that the growth mechanism involves two steps: dominant lateral growth of Li2O2 into disclike structures in the early stage followed by vertical growth with morphology transformation into a toroidal structure.
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