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.