Meso- and micro- porous composite carbons derived from humic acid for supercapacitors

•Humic acid (HA) is adopted as a raw material for synthesis of activated carbons (AC).•The HA-derived ACs show very high specific surface areas (up to 2990.32 m2 g−1).•The HA-derived ACs possess large specific capacitance and good rate performance.•Supercapacitors based on this ACs possess both higher energy and power density.

Herein, humic acid (HA), a kind of biomass (natural polymer), is firstly adopted as a raw material for synthesis of activated carbons (ACs) via a high-temperature activation procedure with KOH. Their porous textures as well as surface groups are fully characterized by N2 sorption isothermal analysis, SEM, TEM, XPS and IR, respectively. The HA-derived ACs show very high specific surface areas (up to 2990.32 m2g−1). Furthermore, electrochemical studies such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD) are carried out to evaluate their specific capacitance and rate capability. It reveals that HA-derived ACs possess high specific capacitance (350 Fg−1) at a scan rate of 5 mV s−1 in 1 M H2SO4. Moreover, supercapacitors based on HA-derived ACs demonstrate good cycling stability in which the 92% initial capacitance has been retained even after 9000 cycle numbers at a high current density of 1 A g−1.

Graphical abstractThe process of synthesis of HA-derived ACs and their applications in aqueous supercapacitors.Figure optionsDownload full-size imageDownload as PowerPoint slide