Boosting the bifunctional electrocatalytic activity of cobalt free perovskite oxide (La0.8Sr0.2)0.95MnO3 via iron doping for high-efficiency Zn–air batteries

Abstract

The representative Mn-based perovskite La0.8Sr0.2MnO3 has drawn extensive interests to substitute noble metal as oxygen reduction and evolution reaction (ORR and OER) in Zn-air battery (ZAB) due to its high oxygen kinetics. However, researches concerning the catalytic activity of the A-site deficient La0.8Sr0.2MnO3 with Fe doping are still scare. In this work, (La0.8Sr0.2)0.95Mn1-xFexO3(x = 0, 0.1, 0.3 and 0.5) perovskites are prepared and developed as bifunctional electrocatalysts. Their structure, morphology, surface adsorbed element state and electrochemical behaviors are characterized. The results demonstrate that Fe doping can increase surface oxygen vacancies, tailor Mn and Fe valence state of the perovskite and thus improve electrocatalytic activity. Among all the perovskite samples tested, (La0.8Sr0.2)0.95Mn0.7Fe0.3O3 (LSMF2) performs the best ORR/OER activity. Except for the good electrocatalytic activity, it also achieves excellent long-term durability compared with Pt/C catalyst. When LSMF2 is applied as the cathode electrocatalyst, a peak power density of 104 mW cm−2 is achieved for the ZAB. Meanwhile, a much lower charge–discharge voltage gap of only 0.9 V than Pt/C catalyst (1.13 V) is obtained. Besides, the proposed ZAB exhibited remarkably high stability during cycling in performance up to 100 cycles. These results highlight perovskite LSMF2 as a very promising electrocatalyst in ZAB.