A Robust Conductive Polymer Network as a Multi-Functional Binder and Conductive Additive for Supercapacitors

This study develops a robust conductive polymer network as a multi-functional binder and conductive additive for activated-carbon-based electrodes for supercapacitors. The robust conductive network is prepared by assembling water-soluble electron-conductive carboxylated polythiophene: (poly[3-(potassium-4-butanoate) thiophene], PPBT) onto poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG, 3P) chains through chemical crosslinking. The homogeneous PPBT-3P crosslinked network facilitates the formation of continuous electron-conducting bridges throughout the electrodes, consequently reducing the electrode resistance, bringing the electrode a relatively high electronic conductivity of approximately 175 S cm(-1), which is nearly five times higher than the widely used electrode with PVDF binder/Super P systems. Moreover, the introduction of a robust crosslinked network into the activated-carbon-based electrode provides robust adhesion force and enhances the electrolyte wetting uptake ability between the active material components and current collector, thereby ensuring the integrity of the whole electrode under folding, device fabrication and cycling. As a result, the supercapacitor device applying this conductive network exhibits an ultra-high specific capacitance of 184.7 F g(-1)at 0.5 A g(-1), and possesses energy densities of 46.7 Wh kg(-1)as well as a long cycling stability (95.6 % capacitance retention) after 5,000 charge-discharge cycles, far superior to the supercapacitor with conventional PVDF binder and comparable to recently reported porous-carbon-based supercapacitors. All of these results guarantee that the novel conductive network can be a promising candidate for developing porous carbon electrodes in supercapacitors.