Preparation Of Perovskite-type Catalysts And Application In Zn-air Battery

Nowadays,the increasing demand for safe,clean and renewable energy in society has inspired scientists to conduct extensive research on electrochemical energy storage and conversion technologies.Due to their rich resources,high specific energy density and the fact that it is environmentally benign,metal-air batteries have become the main research hotspots.There are two main reactions involved in zinc-air batteries:oxygen reduction reaction?ORR?and oxygen evolution reaction?OER?.However,the commercialization of Zn-air batteries has been hindered by their sluggish dynamics.Therefore,it is very important to develop a bifunctional electrocatalyst with high ORR/OER efficiency and long-term stability.Considering the cost,scarcity and durability of the catalyst,the researchers have focused on low-cost and resource-rich perovskite structures.Many reports have reported that ABO₃ type perovskite oxides are used to enhance ORR/OER,such as defect introduction,surface modification,nanostructures and other composite materials.This article will describe how to effectively regulate the perovskite oxide,thereby enhancing its electrocatalytic activity and enabling it to be used in Zn-air batteries.The specific work is as follows:?1?We introduce Ag into Sm_0.5Sr_0.5CoO_3-??SSC?to form a Ag-SSC catalyst by ultrasonication and apply it as the air electrode for a Zn-air battery.It finds that the introduction of Ag into SSC can transform the Ag-SSC into a good bifunctional electrocatalyst towards ORR as well as OER.For instance,a more active half-wave potential for ORR is obtained at 1600 rpm,while the OER overpotential is 0.43V at I=10 mA cm^-2.Further characterization demonstrates that the improved catalyst activity of the Ag-SSC can be assigned to the synergistic effect generated between the Ag and SSC phases.The Zn-air battery with the Ag-SSC as an electrode not only gives a same discharge-charge voltage gap?1.33 V?with that of commercial Pt/C?1.33 V?but also presents an equivalent current efficiency?45.7%for Ag-SSC and 45.3%for Pt/C?at 10 mA cm^-2.Moreover,the stability for110 cycles is better.This result indicates that the Ag-SSC catalyst shows promise for use as a bifunctional electrocatalyst towards OER and ORR.?2?Cerium doped lanthanum manganese perovskite La_1-x-x Ce_xMnO₃?x=0,0.05,0.1 and0.15?were synthesized by sol-gel method.La_0.9Ce_0.1MnO₃ exhibited the highest activity towards ORR and excellent oxygen electrocatalyst for Zn-air battery.The substitution of Ce⁴⁺causes a change in the valence state of the manganese ion and the chemical state of the oxygen species.The change in the ratio of surface elements promotes the reducibility of the catalyst,which plays a key role in catalytic capacity.Overall,the insertion of the A site metal cation is an effective solution to improve the ORR catalytic activity of perovskite in Zn-air battery.