Combinatorial high-throughput optical screening of high performance Pd alloy cathode for hybrid Li-air battery

Abstract

Combinatorial high-throughput optical screening method was developed to find the optimum composition of highly active Pd-based catalysts at the cathode of the hybrid Li-air battery. Pd alone, which is one-third the cost of Pt, has difficulty in replacing Pt; therefore, the integration of other metals was investigated to improve its performance towards oxygen reduction reaction (ORR). Among the binary Pd-based catalysts, the composition of Pd-Ir derived catalysts had higher performance towards ORR compared to other Pd-based binary combinations. The composition at 88 : 12 at. % (Pd : Ir) showed the highest activity towards ORR at the cathode of the hybrid Li-air battery. The prepared $Pd_{88}Ir_{12}/C$ catalyst showed a current density of -2.58 mA $cm^{-2}$ at 0.8 V (vs. RHE), which was around 30 % higher compared to that of Pd/C (-1.97 mA $cm^{-2}$). When the prepared $Pd_{88}Ir_{12}/C$ catalyst was applied to the hybrid Li-air battery, the polarization of the cell was reduced and the energy efficiency of the cell was about 30 % higher than that of the cell with Pd/C.