Magnetically self-assembled 3D micro-pillar supercapacitor with high areal capacitance

초록

Three-dimensional (3D) electrodes are promising architectures for high-performance supercapacitors (SCs) because they increase the electrode-electrolyte interfacial area within a limited footprint. However, current fabrication routes rely on photolithography, high-resolution 3D printing, or vacuum-based processes, which require complex manufacturing steps, thereby limiting their scalability. Herein, we present a magnetic-field-assisted self-assembly strategy in which simply drying a cast Fe3O4 dispersion under an external magnetic field results in the formation of high-aspect-ratio 3D micro-pillar (MP) scaffolds. This microfabrication-free process increases the estimated geometric surface area by ∼69%. To transform the assembled scaffold into an efficient electrode framework, the MPs were rendered highly conductive via an Au enhancement process, followed by MnO2 electrodeposition to maximize charge storage on the 3D architecture. A symmetric SC assembled with these 3D MP electrodes and a gel electrolyte achieved an areal energy density of 59.81 μWh cm−2 and an areal power density of 4.68 mW cm−2, retaining 91.3% of its initial capacitance after 8000 charge-discharge cycles. The proposed strategy provides a low complexity, microfabrication-free route to achieve high-performance 3D electrodes, enabling compact SCs with enhanced areal energy storage and power delivery.

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