Electroconductive
metal–organic frameworks (MOFs)
have emerged
as high-performance electrode materials for supercapacitors, but the
fundamental understanding of the underlying chemical processes is
limited. Here, the electrochemical interface of Cu3(HHTP)2(HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) with an organic
electrolyte is investigated using a multiscale quantum-mechanics/molecular-mechanics
(QM/MM) procedure and experimental electrochemical measurements. Our
simulations reproduce the observed capacitance values and reveals
the polarization phenomena of the nanoporous framework. We find that
excess charges mainly form on the organic ligand, and cation-dominated
charging mechanisms give rise to greater capacitance. The spatially
confined electric double-layer structure is further manipulated by
changing the ligand from HHTP to HITP (HITP = 2,3,6,7,10,11-hexaiminotriphenylene).
This minimal change to the electrode framework not only increases
the capacitance but also increases the self-diffusion coefficients
of in-pore electrolytes. The performance of MOF-based supercapacitors
can be systematically controlled by modifying the ligating group.