On the basis of the characteristics of wide pore size distribution of biomass activated carbon, this study reports a multiscale model to describe the effect of pore structure on electric double layer capacitor. The capacitance of micropores, mesopores, and macropores in H 2 SO 4 and KOH aqueous solutions are simulated by sandwich-type capacitor model, spherical capacitor model, and parallel plate capacitor model, respectively. Chestnut shell is selected as precursor in this experiment. According to the different chemical properties and activation mechanisms, five types of carbon are synthesized by chemical activation using H 3 PO 4 , ZnCl 2 , K 2 CO 3 , and KOH as activators including the one without activation. The influence of carbonization and activation processes on pore structure is studied by the apparent morphology characterization collected by scanning electron microscopy. Detailed pore structure information is obtained by both N 2 adsorption−desorption isotherms and nonlocal density functional theory. By analyzing the effects of pore curvature and densification degree of solvent molecules on the relative dielectric constant ε r and the thickness of the electric double layer d at the electrode− electrolyte interface, it is revealed that carbon materials have a sieving effect on electrolyte ions. The capacitance measured by galvanostatic charge−discharge is in good agreement with the simulated value, which indicates that the parameters in the model can reasonably predict the capacitance behavior of hierarchical porous carbon. This work provides a feasible scheme for estimating the electric double layer capacitance produced by hierarchical porous carbon, which can help in electrode materials selection in supercapacitors with different electrolytes.
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