Synergistic Effects of Phosphorus and Boron Co-Incorporated Activated Carbon for Ultrafast Zinc-Ion Hybrid Supercapacitors

The rapid expansion of the development of the electrochemical capacitor appliance and its industry areas has created the need for long cycling stability of over 30 000 cycles along with an ultrafast performance (referred to as ultrafast longevity). In recent years, zinc-ion hybrid supercapacitors (ZICs) are considered to be emerging energy storage applications thanks to their high specific capacity and remarkable cycling stability. However, ZICs still face serious challenges in overcoming the ultrafast performance and lifetime limitations related to the cathode materials, activated carbon (AC), due to inadequate electrical properties and poor wettability between the electrolyte and the electrode, which cause reductions in specific capacity and lifetime rapidly at high current densities during cycling. To address these drawbacks, a novel phosphorus (P) and boron (B) codoped AC (designated P&B-AC) is presented herein with enhanced electrical properties due to B-doping along with improved wettability due to P-doping to provide an ultrafast longevity ZICs. The prepared ZICs display a superior electrochemical performance with an excellent specific capacity of 169.4 mAh g^-1 at 0.5 A g^-1, a remarkable ultrafast performance of 84.0 mAh g^-1 at 10 A g^-1, and outstanding ultrafast longevity indicated by an 88% capacity retention for up to 30 000 cycles at 10 A g^-1. The excellent energy storage ability is firmly ascribed to the P and B codoping synergistic effect, leading to a superior diffusion capability of Zn ion and charge-transfer process of the AC cathode.