Rapid low-temperature synthesis of perovskite/carbon nanocomposites as superior electrocatalysts for oxygen reduction in Zn-air batteries

Abstract

The conventional ceramic synthesis of perovskite oxides involves extended high-temperature annealing in air and is unfavorable to the in situ hybridization of the conductive agent, thus resulting in large particle sizes, low surface area and limited electrochemical activities. Here we report a rapid gel auto-combustion approach for the synthesis of a perovskite/carbon hybrid at a low temperature of 180 °C. The energy-saving synthetic strategy allows the formation of small and homogeneously dispersed LaxMnO3±δ/C nanocomposites. Remarkably, the synthesized La0.99MnO3.03/C nanocomposite exhibits comparable oxygen reduction reaction (ORR) activity (with onset and peak potentials of 0.97 and 0.88 V, respectively) to the benchmark Pt/C due to the facilitated charge transfer, optimal eg electron filling of Mn, and coupled C–O–Mn bonding. Furthermore, the nanocomposite efficiently catalyzes a Zn-air battery that delivers a peak power density of 430 mW·cm−2, an energy density of 837 W·h·kgZn−1 and 340 h stability at a current rate of 10 mA·cm−2.