Transition Metal Oxides As Promising Bifunctional Electrode Materials For Supercapacitors And Catalysts For Cathode Of Lithium-O₂Batteries

Low-cost transition metal oxides, such as manganese oxide, ferric oxide, cobalt oxide, andnickel oxide are optimal alternation as new multi-functional materials especially because theyexhibit high capacity and power density as electrode for supercapacitor and efficient andenvironment-friendly cathode catalysts for lithium-air/oxygen (Li-air/O2) battery. Moreover,their metallic minerals abound in nature and are economized to exploit.In this thesis, we studied several transition metal oxides and their electrochemical potentialas electrode materials for supercapacitors and catalysts for air breathing cathode of Li-O2batteries. The main work is shown below.(1) Systhesis and electrochemical properties of binary transiton metal oxides, CoFe2O4, forpromising bifunctional electrode materials of supercapacitorIn this work, a promising mesoporous cobalt iron oxide (CoFe2O4) electrode material forsupercapacitors was synthesized via a chemical co-precipitation method using aluminum nitrate(Al(NO3)3) as a precursor of aluminum oxide (Al2O3) hard template, which was etched offafterwards by heavy aniline immersion. This Al-CoFe2O4(for short) material by co-precipitationtemplate method outperformed the CoFe2O4synthesized by common co-precipitation method inspecific capacity and long cycle life and was more appropriate for bifunctional electodematerials. It is novel and promising whether the template method or the bifunctional materialsconcept we proposed and deserved further studying.(2) Transition metal oxides as catalyst for air breathing cathode of lithium-oxygen batteries.Based on amounts of reseach work and practices, a Li-air/O2battery with novelconfigueration was designed. Moreover, we synthesized three types of manganese oxide (MnxOy)and NiMn2O4different in morphology and nature and further studied their performance ascatalyst for air breathing cathode of lithium-oxygen (Li-O2) batteries on the new batterystructure we designed. It was verified that all the catalysts take a certain effect on the cycle lifeperformance of Li-O2battery. Moreover, the battery character differs with the morphology andspecies of catalysts.