Time and cost efficient post-synthesized core-shell NiCo-MOFs electrode for solid-state supercapacitors

Designing electrode materials with a core-shell structure proves to be an efficient strategy for achieving high conductivity and surface area in supercapacitors (SCs), facilitating improved charge transfer and faradaic reactions. Leveraging the advantages of core-shell architectures for SCs, we synthesized binder-free Co-MOFs (CMFS) and core-shell NiCo-MOFs (NCMFS) electrodes through a facile chemical process on stainless steel substrates. Morphological analysis reveals interconnected leaf-like structures for CMFS and a porous sheet-like morphology for NCMFS electrodes. Further, the structural, morphological, and compositional analysis reveals the existence of a core-shell NiCo structure in the NCMFS electrode. This unique architecture significantly enhances electrochemical properties, as evidenced by a specific capacitance of 1016 F/g, substantially surpassing that of CMFS (557 F/g) at 2 A/g. Impressively, both materials demonstrate excellent cycling stability, a critical parameter for real-time SCs applications. Furthermore, symmetric solid-state SCs NCMFS//NCMFS device exhibited an energy density of 8.19 Wh/kg, a power density of 2117 W/kg at 4 A/g, and a 67% retention rate over 3000th cycles. The study highlights the importance of core-shell structures in enhancing the performance of SCs. Moreover, it demonstrates the efficacy of post-synthesis methodologies in surpassing traditional hydro- thermal and solvothermal approaches for producing advanced energy storage devices. This approach offers significant advantages in terms of time efficiency and cost-effectiveness.