A series of n-type hyperbranched polymers exhibiting variable porosity and excellent electrochemical stability are presented for use as the cathodes of asymmetric supercapacitors. The polymers are designed with triphenyl-amine (TPA) cores and naphthalene diimide (NDI) terminal units, with NDI being chosen for its electrochemical stability under reduction. A different number of thiophene rings between the TPA and NDI units are used to alter the porosity. These devices show very good stability over 500 cycles as a result of the stable NDI unit, and nitrogen adsorption experiments confirm that the addition of thiophene spacers results in a concomitant increase in the polymer matrix pore size. Electrochemical impedance spectroscopy (EIS) characterization reveals that as the porosity of the polymer increases, the diffusion resistance decreases. However, as the pore size increases, the charge transfer resistance and equivalent series resistance increases. Finally, one of the polymers is used to fabricate proof-of-concept symmetric supercapacitors.