Spindle-shaped MIL-88A-derived Fe3C@carbon fabric as binder-free flexible electrode for enhanced supercapacitor performance

초록

Flexible electrodes that simultaneously provide high rate capability and long-term stability (>90% capacitance retention), such as those derived from MILs (metal-organic frameworks (MOFs) developed by the Materials Institute Lavoisier), are crucial for next-generation wearable energy-storage devices. Here, we present an Fe-seeding strategy for the in situ growth of MIL-88A on cotton fabric, followed by controlled carbonization, to construct hierarchical Fe3C/conductive carbon electrodes for use in flexible supercapacitors. The optimized architecture promotes the uniform growth of spindle-shaped MIL-88A and its transformation into a conductive, defect-engineered porous network rich in electroactive sites. The resulting electrode delivers a high areal capacitance of 1564 mF & centerdot;cm(-2)at a current density of 1 mA & centerdot;cm(-2), with an excellent rate capability (approximate to 80-85% capacitance retention at 20 mA & centerdot;cm(-2)) and near-unity Coulombic efficiency. The electrode also achieves an energy density of 217 & micro;Wh & centerdot;cm(-2)at a power density of 2 mW & centerdot;cm(-2), outperforming many previously reported MOF-derived systems. Furthermore, the device exhibits excellent cycling stability, retaining approximately 93% of its initial capacitance after 10,000 charge-discharge cycles. Cyclic voltammetry and galvanostatic charge-discharge measurements demonstrate that it has stable performance during extended operation within potential windows of up to 1.4 V. Mechanistically, this excellent performance results from the synergistic combination of hierarchical porosity, improved electrical conductivity provided by Fe3C, and fast surface-controlled pseudocapacitive reactions. This work establishes a scalable method for engineering MIL-derived textile electrodes with optimized structure-property relationships for high-performance flexible energy-storage applications.

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