3D-printed, high-energy-density, current collector-free flexible micro-supercapacitors based on CNT@V2O5 nanowires

Herein, we present current collector-free, high-performance micro-supercapacitors (MSCs) fabricated by 3D extrusion-based printing. To this end, we develop printable hybrid electrode inks by combining V2O5 nanowires (NWs) and carbon nanotubes (CNTs). The performance of the hybrid electrodes is optimized by rationally tailoring the V2O5 NW-to-CNT ratio. Owing to the high conductivity of the hybrid electrodes, the resulting MSCs could operate even without a current collector. Additionally, we improve the areal capacitance by increasing the mass loading per unit area through multiple printing in the vertical direction. The final multilayered MSCs exhibit outstanding energy-storage characteristics, including a high areal capacitance (18.98 mF/cm2 at 0.05 mA/cm2), a high energy density of 5.93 μWh/cm2 at a power density of 39.99 μW/cm2, excellent cycle stability (10,000 cycles), and reliable operation under mechanical deformation.