Mechanochemically Synthesized RuO2‐Doped LaMnO3 Perovskites as Bifunctional Cathodes for Rechargeable Zn/Air Batteries

Herein, we have developed LaMnO3 (LMO) perovskite‐based electrocatalysts of oxygen reduction and oxygen evolution reactions (ORR and OER) in a basic aqueous solution. Mechanochemical grinding and thermal annealing leads to highly‐pure perovskites as shown by X‐ray diffraction. This methodology also allows doping the LMO perovskite with RuO2, thus improving its catalytic activity, especially the oxygen evolution reaction. ORR have been analyzed by rotating ring‐disk electrode (RRDE). Eventually, these catalysts are employed in Zn/air batteries resulting in specific capacity values of 12.76 Ahg−1 at 1 Ag−1, when LMO‐RuO2 (LMO−Ru) was used as catalyst in the positive electrodes. Besides, high operational stability of Zn/air batteries for over 100 cycles was obtained, saving 1.46 mWh per cycle when LMO−Ru was used with respect to pure LMO. This article highlights the synthesis of new LaMnO3 perovskites in which RuO2 has been incorporated in order to increase its behavior as an electrocatalyst for the oxygen evolution reaction (OER). Air electrodes made with this catalyst have been tested in zinc‐air batteries, demonstrating a significant improvement in energy efficiency for a long life of 100 charge/discharge cycles.