Enhanced electrocatalytic performance of Co3O4/Ketjen-black cathodes for Li-O2 batteries

A series of Co3O4/Ketjen Black cathodes are fabricated by electrostatic spray deposition technique for Li -O-2 batteries. A sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction processes is noted either when Co3O4 is lacked or Ketjen Black is insufficient, which leads to much higher over-potentials between charge and discharge profiles. By contrast, with the optimal design in terms of electric conduction and catalytic activity, the Co3O4/Ketjen Black (80 wt%) composite achieves enhanced electrochemical performance with an initial discharge capacity of 2044 mAh g(-1) and maintaining 33 cycles at a fixed capacity of 500 mAh g(-1). The electrochemical characterization indicates that the improved Li-O-2 battery performance may benefit from the highest oxygen reduction reaction and oxygen evolution reaction activity under this electro-chemically optimized composite. This work may shed light on the design principle of future cathode materials for Li-O-2 batteries. (C) 2015 Elsevier B.V. All rights reserved.