IrO2 nanoparticles highly dispersed on nitrogen-doped carbon nanotubes as an efficient cathode catalyst for high-performance Li-O2 batteries

Abstract

Abstract An efficient ORR and OER catalyst is urgently needed to rapidly promote the practical application of Li-O 2 batteries. Herein, we prepared a new bifunctional catalyst by anchoring highly dispersed IrO 2 nanoparticles on nitrogen-doped carbon nanotubes (N/CNTs) via a simple hydrothermal method. By comparing with the CNTs and N/CNTs, Li-O 2 battery with the IrO 2 -N/CNTs catalyst shows the lowest overpotential due to the superior ORR and OER activity. Furthermore, the Li-O 2 batteries with IrO 2 -N/CNTs as the cathode catalyst demonstrate high specific capacity, excellent capacity retention ability and superior cycling stability, it shows a high reversible capacity of 6839 mAh g −1 and achieve an enhanced capacity retention rate of 94.1% after eight cycles at 100 mA g −1 , maintaining a long cycle life for more than 160 cycles without sharp decay under a limited capacity of 600 mAh g −1 at 200 mA g −1 . We found that the high performance of the IrO 2 -N/CNTs catalyst could be attributed to the highly-interconnected carbon nanotubes network provide sufficient space for the deposit of discharge product and facilitation of O 2 /electron transfer, the nitrogen-doping process enhance ORR activity and electrical conductivity, and the highly dispersed IrO 2 nanoparticles perform outstanding OER activity.