Electrochemical Evaluation of Surface Modified Free-Standing CNT Electrode for Li–O₂ Battery Cathode

Abstract

In this study, carbon nanotubes (CNTs) were used as cathodes for lithium–oxygen (Li–O2) batteries to confirm the effect of oxygen functional groups present on the CNT surface on Li–O2 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–O2 batteries.

Keywords

• Li–O₂ battery
• air cathode
• CNT
• oxygen functional groups
• titration