Abstract Herein, a novel conductive poly(N-phenylglycine) (PNPG) polymer was successfully prepared, by in situ electrochemical polymerization method (+0.75 V versus Ag/AgCl) for 10 min, on flexible stainless-steel plate coated with a thin Au film (Au/SS) to serve as a binder-free pseudocapacitive PNPG/Au/SS electrode for energy storage devices. Compared to the electrode without Au coating, PNPG/Au/SS electrode exhibited better electrochemical performance with larger specific capacitance (495 F g −1 at a current density of 2 A g −1 ), higher rate performance and lower resistance, which are good indications to act as a positive electrode for asymmetric supercapacitor devices. Combined with activated carbon as a negative electrode, an asymmetric supercapacitor device was constructed. It displayed a specific capacitance of 38 F g −1 at a current density of 0.5 A g −1 and an energy density of 5.3 Wh kg −1 at a power density of 250 W kg −1 . Experimentally, two asymmetric supercapacitor devices were connected in series to power a home-made windmill continuously for 8 s, revealing the high potential of this novel conductive polymer material for energy storage application.