Synergistic enhancement of electrochemical performance of NiFe2O4@Ni-MOF nanoflake hybrids for high-performance energy storage applications

Abstract

In this study, a novel method is investigated for the enhancement of electrochemical performance of metal–organic frameworks (MOFs), particularly Ni-MOFs, which have traditionally encountered challenges in energy storage applications owing to their limited electrical conductivity and stability. A two-step process for the formation of Ni-MOF arrays on NiFe₂O₄ (NFO) nanoflakes is introduced. This strategy exploits the distinctive characteristics of the NFO core and the Ni-MOF shell, coupled with their synergistic effects, to significantly augment the performance of the electrode. For the core–shell electrode composed of the NFO@Ni-MOF, a specific capacitance of 1250 F g⁻¹ was determined, which significantly surpasses the capacitance of the pristine NFO and Ni-MOF (538 F g⁻¹ and 662 F g⁻¹) electrodes, respectively, at a scan rate of 10 mV s⁻¹ in 1 M KOH electrolyte. Moreover, the synthesized NFO@Ni-MOF hybrid electrode demonstrated a substantial increment in specific capacitance of 936 F g⁻¹ at 36 mA g⁻¹ and high rate capability as demonstrated by GCD. Moreover, a HASC device, utilizing the optimized NFO@Ni-MOFs as the anode and activated carbon as the cathode, was assembled. This device attained a high energy density of 35.6 W h kg⁻¹ at a power density of 7200 W kg⁻¹, retaining excellent cycling stability of 84.4% and mechanical robustness over prolonged cycles, surpassing many recent MOF-based HASC devices with the PVA–KOH gel electrolyte. This research highlights the potential of novel MOF-based hybrid materials in propelling forward the field of energy storage technologies.