Fe3O4@PPy@MnO2 ternary core-shell nanospheres as electrodes for enhanced energy storage performance

Abstract

Fe 3 O 4 @PPy@MnO 2 ternary core-shell nanospheres are synthesized by facile solvothermal, in-situ polymerization, and redox reactions.The nanocomposite exhibits excellent electrochemical performance with specific capacitance of 751F g −1 at 1 A/g and remarkable cycling stability (87.0% capacitance retention after 5000 cycles at 4 A/g). The asymmetric supercapacitor devices assembled with Fe 3 O 4 @PPy@MnO 2 nanocomosite possess remarkable cycling stability (95.2% after 5000 cycles at 5 A/g) and high energy density (71.3 Wh kg −1 at the power density of 750 W kg −1 ). • Fe 3 O 4 @PPy@MnO 2 ternary core-shell nanospheres are synthesized. • The electrode exhibits high specific capacitance and good cycling stability. • The asymmetric supercapacitor devices possess high energy density. The rapid development of supercapacitors has led to increasing demand for electrode materials with excellent electrochemical properties. In this study, Fe 3 O 4 @PPy@MnO 2 nanocomposites with porous core and double-shell layers were successfully synthesized and utilized as supercapacitor electrode materials. Specifically, a dense PPy coating is formed on the porous Fe 3 O 4 surface to ensure high structural stability, and a MnO 2 shell layer could be easily introduced on the PPy surface through the redox reaction between PPy and KMnO 4 . The prepared composite electrode material has the advantages of high specific surface area, short diffusion distance of electrolyte ions, good electron transfer, and fast and reversible Faraday reaction. The Fe 3 O 4 @PPy@MnO 2 electrode not only exhibits high specific capacitance (751F g −1 at 1 A/g), but also exhibits excellent cycling stability (87.0 % capacitance retention after 5000 cycles at 4 A/g). This is owing to the synergistic effect of the porous Fe 3 O 4 core, the dense PPy coating, and the MnO 2 nanosheet shell. Furthermore, the asymmetric supercapacitor devices assembled with Fe 3 O 4 @PPy@MnO 2 nanocomosite possess remarkable cycling stability (95.2 % after 5000 cycles at 5 A/g) and high energy density (71.3 Wh kg −1 at the power density of 750 W kg −1 ). These results demonstrate the great potential of Fe 3 O 4 @PPy@MnO 2 nanocomposites with porous cores and double shells as electrode materials for high-performance supercapacitors.