Mn3−xFexO4 Hollow Nanostructures for High-Performance Asymmetric Supercapacitor Applications

Graphical A large amount of Fe 2+ was induced into Mn 3 O 4 nanoparticles through effective electrodisplacement reaction to synthesize Mn 3− x Fe X O 4 hollow nanostructures. By changing the addition of Fe 2+ , elemental compositions and structures of Mn 3− x Fe x O 4 could be well adjusted. The remarkable performance of Mn 3− x Fe x O 4 hollow nanostructures in pseudocapacitor applications is demonstrated. Compared with the original Mn 3 O 4 , the electrochemical performance of the obtained porous Mn 3− x Fe x O 4 nanostructure is significantly improved. Design of hollow nanostructure and controllable phase of mixed metal oxides for improving performance in supercapacitor applications is highly desirable. Here we demonstrate the rational design and synthesis of Mn 3−x Fe x O 4 hollow nanostructures for supercapacitor applications. Owing to high porosity and the specific surface area that provides more active sites for electrochemical reactions, the electrochemical performance of Mn 3−x Fe x O 4 hollow nanostructure substantially enhanced comparing with pristine Mn 3 O 4 . Particularly, in 1.0 M KOH electrolyte, Mn 0.16 Fe 2.84 O 4 with a typical diameter of 20 nm exhibits excellent specific capacitance of 2675, 2320, 1662, 987 F g −1 at current densities of 1, 2, 5, 10 A g −1 , respectively, which is significantly superior to those of other transition metal oxides. Besides, an asymmetric supercapacitor is assembled by using Mn 0.16 Fe 2.84 O 4 and activated carbon as a positive and a negative electrode, respectively. Electrochemical results indicate a high energy density of 42 Wh kg −1 at a power density of 0.75 kW kg −1 , which makes this hollow nanostructure a highly promising electrode for achieving high-performance next-generation supercapacitors.