Porous polypyrrole-derived carbon nanotubes as a cathode material for zinc-ion hybrid supercapacitors

Aqueous zinc-ion hybrid supercapacitors (ZISCs) are a kind of energy storage device with promising applications due to their easy assembly, low cost, safety and reliability. Polypyrrole (PPy)-derived carbon is usually used as a cathode material for ZISCs with N-doping originating from the polymer structure and simple preparation. Herein, the porous PPy-derived carbon nanotubes (PCNTs) are prepared by calcination and KOH activation. The microstructure and physicochemical properties of PCNTs can be optimized by regulating the mass ratio of KOH to PPy-derived carbon. The high specific surface area (3537 m 2  g −1 ), hierarchical porous structure , and high contents of O/N-codoping (12.02 at.% and 3.39 at.%), the PCNTs process high specific capacity and excellent cyclic stability. ZISCs based-PCNTs cathode and Zn anode obtain a high specific capacity of 387.8 mAh g −1 at a current density of 0.2 Ag −1 , superior rate capability (127.2 mAh g −1 at 20 Ag −1 ), large energy density (151 Wh kg −1 ), and power density (12.695 kW kg −1 ). Furthermore, after 10,000 GCD tested at 5 A g −1 , the capacity retention of ZISCs is 90.9 %. This study provides a valuable reference for regulating the microstructure of porous carbon derived from other polymers and promoting its application in aqueous ZISCs.