Nitrogen heteroatom anchored on porous carbon cathode for zinc ion hybrid capacitor.

• Nitrogen heteroatom porous carbon (NPC) was prepared by oxalate activation strategy. • The NPC presents moderate heteroatom contents and hierarchical pore structures. • The NPC cathode displays large capacity, high energy density and long cycle life. Heteroatom doped porous carbons have been widely used in aqueous zinc ion hybrid capacitors (AZICs) due to their merits of simple preparation process, excellent electric conductivity and abundant expose active sites. However, toxic and corrosive processes hinder their further applications. Herein, we report a template-free strategy to prepare nitrogen doped porous carbons from coal tar pitch for AZICs. Due to the structural characteristics of hierarchical pores and N, O heteroatoms, the AZIC fabricated by cathode presents the highest discharge capacity (133.1 mAh g−1), the maximum energy density (112.3 Wh kg−1), an excellent rate performance (65.9 Wh kg−1 at 15.26 kW kg−1) and a superior cycle stability over 15,000 cycles. This study points to an environmentally-friendly strategy to construct heteroatom-doped porous carbons for high-performance AZICs. [ABSTRACT FROM AUTHOR]