La0.7(Sr0.3-xPdx)MnO3 as a highly efficient electrocatalyst for oxygen reduction reaction in aluminum air battery

- Sr is substituted with Pd in LSM by a facile sol-gel method.
- Oxygen desorption ability can be enhanced with the appropriate Pd substitution.
- LSPM-15 shows the remarkable catalytic activity and stability during ORR.
- Pmax of the Al-air battery with LSPM-15 reaches 265.6 mW cm−2.

The La1-xSrxMnO3 (LSM) perovskites have been proposed as the promising oxygen reduction reaction catalysts (ORRCs) to substitute the noble metal. However, their ORR catalytic activities still need to be further improved. Here, the La0.7(Sr0.3-xPdx)MnO3 (LSPM) perovskites with the substitution of Sr with Pd are synthesized by a facile sol-gel method. The structure, morphology, valence state of Mn, oxygen adsorption behaviors of the different LSPM catalysts are investigated, and their ORR catalytic activities are studied by the rotating ring-disk electrode (RRDE) and aluminum air battery technologies. The results demonstrate that the appropriate substitution of Sr with Pd can effectively improve the ORR catalytic activity of La0.7Sr0.3MnO3 due to the regulation of the Mn valence and enhancement of the oxygen adsorption capacity. Among the LSPM perovskites, the LSPM-15 catalyst exhibits the best catalytic activity toward ORR. In addition, the current retention of LSPM-15 is as high as 98.9% after 10000 s with the generation of a few HO2− (0.96% ∼ 1.56%) during the whole aging test. Moreover, the maximum power density of the aluminum air battery using LSPM-15 can reach 265.6 mW cm−2, which indicates that LSPM-15 can be used as a promising ORRC for the aluminum air batteries.