Effect of Sr substitution in La1-xSrxMn0.7Co0.3O3 perovskites and their application in Zn-air batteries
J.X. Flores-Lasluisa, M. García‐Rodríguez, Diego Cazorla‐Amorós, Emilia Morallón
Abstract
La 1-x Sr x Mn 0.7 Co 0.3 O 3 perovskite materials were synthesized by a sol-gel method for their application as an air electrode in Zn-air batteries. Through physicochemical techniques, it was determined that the Sr substitution level influences the crystallite size and purity degree of the perovskite structure. Moreover, the surface chemistry, including oxygen chemisorbed species and different oxidation states of 3d cations, can be tailored through the Sr substitution level. The metal oxides were mixed with carbon black (Vulcan XC-72R) to improve the electrochemical performance. Temperature Programmed Desorption (TPD) and Temperature Programmed Reduction (TPR) studies revealed the strong interaction existing between both components, which tends to increase with the Sr substitution level due to the smaller crystallite size. However, low Sr substitution level results in better electrocatalytic performance because of a moderate concentration increase of Mn 4+ and oxygen chemisorbed species. Moreover, it helps to preserve the perovskite structure and increases the concentration of Co 3+ species, which are more catalytic towards OER. Thus, the La 0.8 Sr 0.2 Mn 0.7 Co 0.3 O 3 /Vulcan material was studied in a Zn-air battery and compared to a commercial Pt/C + RuO 2 electrocatalyst. The material shows comparable long-term charge-discharge performance to Pt/C + RuO 2 after 20 h of cycling. • La 1-x Sr x Mn 0.7 Co 0.3 O 3 perovskite synthesized for their application as an air electrode in Zn-air batteries. • Low Sr substitution results in better electrocatalytic performance due to stabilization of Mn 4+ . • Low Sr substitution increases the concentration of Co 3+ species which is beneficial for OER.