N-Doped Hierarchically Porous Carbon Aerogels by Controlling the Zn–Chitosan Complex Ratio for High-Performance Supercapacitors

Abstract

In this paper, we have successfully synthesized Zn–chitosan aerogels by freeze drying and further obtained N-doped hierarchically porous carbon (NHPC) aerogels through a one-step carbonization process. Zn ions as activators and soft templates can efficiently fabricate hierarchical porous structures in a carbon matrix. By adjusting the ratio of zinc–chitosan complexes, the structure and morphology of NHPC can be controlled. In three-electrode systems, the optimal NHPC shows a superior capacity of 230 F g–1 (0.5 A g–1) and excellent cycle stability. In two-electrode systems, the symmetric supercapacitors deliver a high energy density and power density in aqueous electrolytes (4.67 W h kg–1 and 5101 W kg–1, respectively). Our work provides a prospect for the efficient preparation of biomass porous carbons and the development of high-performance supercapacitor electrode materials.