Metal-organic framework-derived NiS@Cobalt-Molybdenum layered double hydroxides shell@core as cathode and CoFe₂O₄-nanoparticles@MXene shell@core as anode materials for ultra-high energy-density flexible asymmetric supercapacitor

Modern electronics industries-based on portable and wearable devices, urgently needed the design and fabrication of high-performance flexible electrochemical supercapacitors. However, the low specific capacitance and deprived rate-capability of cathode and anode electrode materials are two prominent hurdles in obtaining the optimal electrochemical performance of flexible asymmetric supercapacitors (ASCs) devices. Herein, for the first time, metal-organic framework-derived shell@core and MXene-supported shell@core strategies are reported to fabricate high-performance cathode and anode electrode materials, respectively for sustainable flexible asymmetric supercapacitor. The NiS@Co–Mo–LDHs shell@core as cathode and Co–Fe–O–nanoparticles@MXene as anode electrodes demonstrate high areal capacities of 1.43 and 0.949 mA h cm⁻², respectively at a current density of 1 mA cm⁻². Benefiting from the commendable individual electrochemical performances of the cathode and anode electrode materials, the as-assembled NiS@Co–Mo–LDHs//Co–Fe–O@MXene flexible all-solid-state asymmetric supercapacitor (FSS-ASC) device exhibits an excellent energy density of 90.2 W h Kg⁻¹ with superior capacitance retention up-to 90.6 % after 10,000 cycles. Furthermore, after flexibility testing, the NiS@Co–Mo–LDHs//Co–Fe–O@MXene FSS-ASC device also retains excellent electrochemical properties. These electrochemical findings reveal that the NiS@Co–Mo–LDHs shell@core and Co–Fe–O@MXene shell@core electrode materials are the appropriate candidates for the development of high-performance flexible energy storage devices.