High Mass-Loading Vanadium Oxide on 3D Printed Carbon Lattices for Zinc-Ion Supercapacitors

The rising demand for sustainable and scalable energy storage systems has accelerated the development of aqueous zinc-based technologies. However, conventional slurry-cast planar electrodes underperform at high mass loading, causing low areal capacitance and sluggish rate performance. Herein, we introduce a 3D printed freestanding, binder-free conductive carbon lattice electrode integrated with vanadium oxide (VO_x). The 3D framework facilitates homogeneous dispersion of VO_x, increasing the electroactive surface area, enhancing the ion transport ability, and maintaining structural integrity under high current density. Enabled by this architecture and a high mass loading of 38 mg cm^-2, the electrode achieves areal capacitance of 7129 mF cm^-2 at 3 mA cm^-2, areal power and energy densities of 44 mW cm^-2 and 1 mWh cm^-2, along with robust cycling performance, with a capacity retention of 82% after 1500 cycles. To ensure rigorous and reproducible evaluation, we introduce a sealed, 3D-printed test cell that fixes the inter-electrode spacing and suppresses electrolyte evaporation. Compared with open beaker setups commonly used for three-electrode measurements, the printed cell yields more consistent capacitance and resistance. It also maintains 98% capacity retention after 1400 cycles. This synergy of 3D engineered electrodes and cells provides a reproducible pathway to practical, high-energy, and power-density zinc-ion supercapacitors.