DFT has been widely applied to explain the origin of dramatic improvement of capacitance in MOFs, which was found to arise from pseudo-capacitance. Collaborating with experimental measurements, phthalocyanine-based nickel-bis(dithiolene) (NiS4)-linked 2D MOFs were studied with DFT and the redox mechanism was unveiled, with a two-step reduction reaction occurring on the MOF ligand. It was found that intercalation-type pseudocapacitance mechanism is also possible in MOF supercapacitors between the in-pore Li + and the ligating groups of the MOF by matching experimental IR measurements with DFT results.