S and O doped porous carbon hollow bubble for Zn ion capacitors with enhanced energy density and long life

Zinc ion capacitors (ZICs) as a promising energy storage systems suffer low energy density and poor cyclic stability, leading to increasing attention to the development of porous carbons. Herein, S and O co-doped porous carbon hollow bubble (S-O-PC-HB) was prepared. The obtained S-O-PC-HB displays 3D porous framework structure to shorten the Zn2+ transport path. S and O dopants introduce more defects and then promote Zn2+ storage capability. The S-O-PC-HB as cathode for ZICs exhibits the largest energy density of 95.68 Wh kg-1 at 178 W kg-1. The assembled ZICs delivers a long cycling stability (92.4 % capacity retention after 20,000 cycles), which presents an alternative practice for high-performance ZICs.