Building mesoporous channels in lignin-derived microporous carbons to remold the electrochemical behaviors of supercapacitors

The mesoporous structure of the porous carbon electrodes could promote the in-pore diffusion of electrolyte ions. However, the effect of large mesopores with pore sizes larger than 20 nm in the microporous carbons on the diffusion of different electrolyte ions remains unclear. Herein, porous carbon electrodes with mesopores sizes of 23 nm and 40 nm, respectively, are prepared using the ZnO as a hard template. The electrochemical behavior of porous carbon electrodes with large mesopores and microporous carbon electrodes in different sulfate electrolytes are studied and compared. Electrochemical impedance spectroscopy (EIS) tests demonstrate that the wide and short diffusion path provided by large mesopores can reduce the hindrance of multivalent metal cations and SO42−, thus significantly improving the diffusion efficiency of the multivalent metal sulfate cations. Due to the small size and low valence of monovalent metal ions, it is difficult for large mesopores to promote the diffusion of monovalent metal sulfate ions. Therefore, the large mesopores have little impact on the diffusion of monovalent metal ions, whereas they significantly enhance the diffusion of multivalent metal ions. [Display omitted] •Mesoporous channels are built by ZnO hard templates.•Mesoporous channels significantly improve the rate performance.•The effect of the addition of mesoporous channels on electrochemical behavior.•The short diffusion path is favorable for ion diffusion.