Nanostructured zinc-doped nickel/iron metal–organic framework electrode material for an efficient energy storage
摘要
Developing electrode materials that simultaneously provide high redox activity, rapid charge transport, and long-term stability is crucial for advancing next-generation supercapacitors. In this study, a series of metal–organic frameworks (MOFs), including Ni-MOF, Fe-MOF, bimetallic Ni/Fe-MOF, and Zn-doped Ni/Fe-MOF, were rationally synthesized and comprehensively evaluated to establish clear correlations between their structural features and electrochemical behavior. Among these, the Zn-doped Ni/Fe-MOF exhibited the most outstanding electrochemical behavior, attributed to the synergistic effects of dual-metal coordination and Zn incorporation, which collectively enhanced electrical conductivity and increased the accessible electroactive surface area. When applied as the positive electrode in an aqueous asymmetric supercapacitor (ASC) using activated carbon (AC) as the negative electrode and 2M KOH electrolyte, the Zn-doped Ni/Fe-MOF delivered a high specific capacitance of 102.31 F g⁻1 at 1 A g⁻1 and retained 71.03 F g⁻1 at 10 A g⁻1. The assembled ASC also achieved an energy density of 23.45 Wh kg⁻1 at a power density of 803.77 W kg⁻1, along with excellent cycling stability, maintaining 89.42% capacitance retention and ~ 99% coulombic efficiency over 5000 cycles. These findings highlight Zn-doped Ni/Fe-MOF as a promising electrode material for high-performance aqueous ASCs, offering a balanced combination of energy density, power capability, and operational durability.