The Influence of Electrode Microstructure on the Performance of Free-Standing Cathode for Aprotic Lithium-Oxygen Battery

Abstract

Free-standing NiCo2O4@Ni cathodes for aprotic lithium-oxygen batteries were synthesized through a simple hydrothermal process followed by heat treatment in the air. The morphology of the NiCo2O4 deposit changed from nanosheet to nanowire with the increase of hydrothermal time. Further observation revealed that the nanosheet/nanowire NiCo2O4 were assembled by nanoparticles with a size of 10–20 nm. The directional assembly of the nanoparticles were not affected by the reaction time. The influence of catalyst microstructure on the electrochemical performance of Li-O2 batteries was studied. The results of battery tests in pure oxygen indicate that the cathode material with a high specific surface area, large pore volume and broad pore size distribution can facilitate the discharge reaction, leading to an improved cell performance. As a result, the cathode based on the NiCo2O4 nanowire array delivered a specific discharge capacity of 1682 mAh g−1 at 30 mA g−1 and a stable cyclability of 50 cycles with a capacity limitation of 500 mAh g−1.