Synergistic redox enhancement in ternary Mn–ZnFeOOH oxyhydroxides for high-performance supercapacitor applications

Abstract

High-performance electrode materials are vital for developing next-generation supercapacitors with enhanced energy storage capability. Mixed metal oxyhydroxides can exhibit better performance due to their high pseudo-capacitance and tunable redox activity. Thus, introducing another metal led to an enhancement of their electrochemical performance through synergistic effects and the creation of new redox-active sites. Here, Mn was incorporated into ZnFeOOH (FZ) to develop a ternary oxyhydroxide, which demonstrates the effect of Mn (FZMn-0 to FZMn-20) on the structural and electrochemical properties. Among them, FZMn-15 exhibited the most favorable characteristics, achieving a high specific capacitance of 1531 F g⁻¹ at 1 A g⁻¹ in a three-electrode system, while the corresponding asymmetric FZMn-15‖AC device delivered 92 F g⁻¹. Furthermore, charge storage analysis indicated a diffusion-dominated process with additional capacitive contributions, highlighting the combined effect of Mn incorporation on electrochemical activity. These findings demonstrate that Mn-modified ZnFeOOH electrodes can serve as efficient and reliable materials for advanced supercapacitor applications.