120th General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation of Young Scholars in Electrochemistry
Room No. Room 201+202
Time THU 10:15-:
Code ELEC.O-6
Subject The role of solid electrolyte interphase (SEI) on sodium metal in sodium-oxygen batteries
Authors Younguk Jung, Hye Ryung Byon*
Department of Chemistry, Korea Advanced Institute of Science and Technology, Korea
Abstract Metal-oxygen batteries have been paid attention to one of the promising next-generation batteries applied for electric vehicles, thanks to higher energy density than current lithium-ion batteries. However, instability of superoxide (O2–) formed through O2 reduction severely incurs side reaction, which alleviates voltaic efficiency and cycling performance. The lithium-oxygen (Li-O2) batteries typically show large charge overpotential and poor cycling stability. However, the superoxide species is more stable with larger size of alkaline metal ion, resulting in less side reactions, which has been demonstrated in the sodium-oxygen (Na-O2) batteries. Nevertheless, poor cycling performance is still measured, which have not yet fully understood. Here we demonstrate one of the critical reasons for low cycling stability from Na metal as the negative electrode. We observed nanometer size of uneven precipitates that passivate the positive carbon nanotube electrode surface before and after galvanostatic tests. We attributed this unintended deposit to soluble solid electrolyte interphase (SEI) formed from the Na metal interphase, which is in line with depletion of Na metal after cycling. With increasing stability of SEI layer, the precipitate disappears from the carbon electrode surface and discharge overpotential is significantly reduced. In the presentation, I will discuss improving stability of SEI layer on Na metal and the correlated cycling result of Na-O2 battery and Na metal condition in detail.
E-mail zxvc45@kaist.ac.kr