(673f) Study of Electrocatalytic Activity of Oxide-Based Materials in Li-Air Batteries: Towards Enhancing the Rates of Oxygen Evolution Reaction During Charging
Nonaqueous Li-air batteries are among the most promising energy storage technologies due to their high theoretical energy density and specific capacity. In practice, their performance is significantly limited by several factors including the high overpotential losses at the cathode. Among the most commonly used cathode materials for nonaqueous Li-air batteries are porous carbons due to their low cost, light weight, good storing capability for Li2O2 and excellent electron conductivity. In addition, porous carbon-based cathodes have also shown to possess oxygen reduction reaction (ORR) activity during discharge due to their surface functional groups and defect sites. One of the challenges with the carbon-based cathodes for Li-air batteries is the inability to electrocatalyze the oxygen evolution reaction (OER) during the charging process. Therefore, the oxidation of Li2O2 during the charging appears to be catalytically sensitive as shown by various research groups. In this contribution, we will discuss a promising class of oxide-based materials with mixed ionic and electronic conductivity as OER electrocatalysts for Li-air cathodes. We find that these oxides reduce the charging potentials significantly (from 4.2 V to 3.7 V) compared to the standard carbon based cathodes without an OER electrocatalyst. We have been able to control the size and shape of these oxide materials by using a reverse micelle synthesis method and study the effect on the electrocatalytic activity toward OER.