Synergistic effects of B/S co-doped spongy-like hierarchically porous carbon for a high performance zinc-ion hybrid capacitor.

Zinc-ion hybrid capacitors (ZIHCs) are regarded as a potential candidate for large-scale energy storage devices. However, the inadequate cathode and the inferior wettability between the electrode and electrolyte hinder the construction of high-performance ZIHCs. Herein, boron (B) and sulfur (S) co-doped spongy-like hierarchically porous carbon (B 2 S 3 C) is first proposed as a cathode material for ZIHCs. Here, B doping is favorable for improving the wettability, while S doping contributes to enhancing the electrical properties. In addition, the density functional theory (DFT) results uncover that B and S atoms contribute to reducing the energy barrier between Zn 2+ and the cathode, leading to boosted chemical adsorption ability of Zn 2+ on the cathode. As a result, the assembled ZIHC based on B 2 S 3 C exhibits a high specific capacity of 182.6 mA h g -1 at 0.1 A g -1 , an excellent capacity retention of 96.2% after 10 000 cycles and a remarkable energy density of 292.2 W h kg -1 at a power density of 62.2 W kg -1 , superior to the previously reported ZIHCs. Due to the flexibility of the assembled electrodes, the solid-state ZIHC can sustain various deformations. This work paves a feasible path for the development of cost-effective and high-performance porous carbon materials.