Porous current collector enables carbon superior electrochemical performance for K-ion capacitors

The current collector is an indispensable component in potassium-ion hybrid capacitors, which not only provides mechanical support to load electrode materials, but also collects and outputs the current generated. Herein, we investigate the effect of three different current collectors on the electrochemical properties of potassium ion capacitors using carbon black anode as a demonstration. Because of better adhesion and lower charge transfer resistance, the specific capacity of half-cells assembled using three-dimensional (3D) porous copper foil (PCu) and copper as current collector is better than that of Al foil, which stabilizes at 138.2 and 132.8 mAh·g⁻¹ after 100 cycles at 0.05 A·g⁻¹. The potassium-ion capacitor assembled using PCu exhibits an excellent energy/power density of 86.1 Wh·kg⁻¹ and 4000 W·kg⁻¹, respectively. This work will boost the rational design and provide an effective strategy to improve the performance of potassium-ion capacitors.