Electrochemical Evaluation of Surface Modified Free-Standing CNT Electrode for Li-O-2 Battery Cathode

Abstract

In this study, carbon nanotubes (CNTs) were used as cathodes for lithium-oxygen (Li-O-2) batteries to confirm the effect of oxygen functional groups present on the CNT surface on Li-O-2 battery performance. A coating technology using atomic layer deposition was introduced to remove the oxygen functional groups present on the CNT surface, and ZnO without catalytic properties was adopted as a coating material to exclude the effect of catalytic reaction. An acid treatment process (H2SO4:HNO3 = 3:1) was conducted to increase the oxygen functional groups of the existing CNTs. Therefore, it was confirmed that ZnO@CNT with reduced oxygen functional groups lowered the charging overpotential by approximately 230 mV and increased the yield of Li2O2, a discharge product, by approximately 13%. Hence, we can conclude that the ZnO@CNT is suitable as a cathode material for Li-O-2 batteries.