Nitrogen and sulfur co-doped polyurethane-based porous carbon materials as supercapacitors exhibit excellent electrochemical performance

Nitrogen and sulfur porous co-doped carbonized materials were successfully prepared from polyurethane (PU) using KOH as an activating agent with promising electrochemical performances. Many micropores imbedded in the carbon materials are beneficial to electrolyte transport and the resulting specific surface area of the porous samples is up to 2216 m2 g−1 measured by the N2 adsorption–desorption method. The electrochemical performances of the activated carbon samples were tested as supercapacitors in a three-electrode system and the Ragone plot was examined in a two-electrode cell with a 6 M KOH solution as electrolytes. The specific capacitance of porous carbon material PUC-2:1 (the mass ratio of KOH and PUC was 2:1 at an active temperature of 750 °C for 2 h) reaches 395 F g−1 at the current density of 1 A g−1, and the capacitance retention is 95.3% after 4000 charge–discharge cycles at a large current density of 10 A g−1. The energy density of PUC-2:1 is 24.4 Wh kg−1 at the power density of 1080 W kg−1 and still retains 12.6 Wh kg−1 with a high power density of 21.6 kW kg−1 at a high current density of 10 A g−1. Such a high energy density at a large power density provides potential application in high performance of energy storage devices.