Interfacial modification for heightening the interaction between PEDOT and substrate towards enhanced flexible solid supercapacitor performance

Poly(3,4-ethylene-dioxythiophene) (PEDOT) was reported to be an organic electrode material for supercapacitor. But poor stability and small capacitance restrict its further application. Here, we fabricate a new PEDOT-based supercapacitor device where the working electrode is prepared by depositing trace of Ni-rich oxide on the interface between PEDOT and substrate (named as PEDOT-Ni2+/NiO-SS). This PEDOT-Ni2+/NiO-SS half-electrode obtained a higher specific capacitance of 236 F/g, good rate capability and superior cycling stability (99% capacitance retention after 2500 cycles) than those of untreated PEDOT. Subsequently, a flexible all-solid-state asymmetric supercapacitor (ASC) device was fabricated by using PEDOT-Ni2+/NiO-carbon cloth as positive electrode and untreated PEDOT-carbon cloth as negative electrode. An ASC cell presented higher energy density (40.15 Ah/Kg) and power density (1.32 kW/Kg) than the symmetrical supercapacitor device composed of untreated PEDOT. PEDOT-Ni2+/NiO-SS structure could facilitate the insertion of ions from electrolytes into electrode material, achieve long cyclic lifetime and high electrochemical stability. The electrochemical deposition method to modify electrode interface using metal oxide could be a promising strategy and pave the way for the preparation of other supercapacitor electrodes.