Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
A demand for lithium-oxygen (Li-O2) batteries with high storage capacity is increasing due to its application for the energy storage systems and electric vehicles. However, there are still critical bottlenecks for fabrication of a commercial Li-O2 battery. The cyclability of Li-O2 battery is very poor compared to lithium-ion battery. The main reasons for this problem are a variety of side reactions during the battery operation, which inactivate the lithium anode and cathode catalyst. To solve this problem, reversible charge/discharge reactions should be presented. During discharge reaction of Li-O2 battery, various superoxide and peroxide species, such as O2-, LiO2 and Li2O2 appear. These nucleophilic molecules could react with electrolyte and carbon electrode. A dominant portions of side-reactions originate from this process. Therefore, we adopted a catalyst support with surface oxygen-defects to stabilize the nucleophilic molecules. In this study, we used zirconia as a support and observed that electrocatalyst with zirconia support exhibits better cyclability compared to that without support. Experimental and computational approaches are exploited to understand this phenomenon and we found that the reactivity of superoxide and peroxide species decrease with the oxygen-defective support. Our concept proposed in this study could be the clue for the design of cathode catalyst for reversible charge/discharge reactions.