Boosting the electrochemical performance and reliability of conducting polymer microelectrode via intermediate graphene for on -chip asymmetric micro-supercapacitor

High-performance anode is hurdle for on-chip planar microsupercapacitor (MSC). Polypyrrole (PPy) is a highly attractive pseudocapacitive material, but its low cycling stability, and low adhesion with current collector hinder its practicability. Herein we propose one-prong generic strategy to boost the cycling stability of PPy. For our strategy, the electrochemical deposition of multilayered reduced graphene oxide (rGO) on micropatterned Au is utilized, and the resultant rGO@Au pattern is then used for growing highly porous PPy nanostructures by facile electrochemical polymerization. The fabricated PPy anode on rGO@Au has quasi rectangular cyclic voltammetry curves up to -0.7 V and exceptional cycling stability, retaining 82% of capacitance after 10,000 charge/discharge cycles in 2 M KCl electrolyte. The outstanding reliability of PPy on rGO@Au is due to the flexibility of rGO, accommodating structural pulverization and providing a promising background for the nucleation of highly porous nanostructure. Further, an all-polymer based asymmetric aqueous MSC (AMSC) is constructed with PPy anode and PEDOT cathode, which exhibited excellent electrochemical performance compared with conventional symmetric MSCs based on conducting polymers. The constructed AMSC delivered a maximum areal capacitance of 15.9 mF cm−2 (99.3 F cm−3), high specific energy and power densities of 4.3 µWh cm−2 (27.03 mWh cm−3) and 0.36 W cm−2 (0.68 W cm−3) at 1.4 V, respectively. The enhanced electrochemical performances can be illustrated by nucleation mechanism, in which surface topology of rGO generates a promising background for nucleation and electrochemical growth of nanoporous pseudocapacitive conducting polymers with superior interfacial contact and improved surface area. © 2020