Black Liquor and Wood Char-Derived Nitrogen-Doped Carbon Materials for Supercapacitors

Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas (SSAs) of 2481 and 2690 m(2) g(−1), respectively, as well as a high volume of mesopores with an average size of 2.9–4.6 nm. The nitrogen content was approximately 3–4 at% in the synthesized nitrogen-doped carbon materials. A specific capacitance of approximately 81–142 F g(−1) was achieved in a 1 M Na(2)SO(4) aqueous solution at a current density of 0.2 A g(−1). In addition, the specific capacitance retention was 99% after 1000 cycles, indicating good electrochemical stability.