A simple strategy to prepare a layer-by-layer assembled composite of Ni–Co LDHs on polypyrrole/rGO for a high specific capacitance supercapacitor

Abstract

A facile and novel electrode material of nickel-cobalt layered double hydroxides (Ni-Co LDHs) layered on polypyrrole/reduced graphene oxide (PPy/rGO) is fabricated for a symmetrical supercapacitor <i>via</i> chemical polymerization, hydrothermal and vacuum filtration. This conscientiously layered composition is free from any binder or surfactants which is highly favorable for supercapacitors. The PPy/rGO serves as an ideal backbone for Ni-Co LDHs to form a free-standing electrode for a high-performance supercapacitor and enhanced the overall structural stability of the film. The well-designed layered nanostructures and high electrochemical activity from the hexagonal-flakes like Ni-Co LDHs provide large electroactive sites for the charge storage process. The specific capacitance (1018 F g^-1 at 10 mV s^-1) and specific energy (46.5 W h kg^-1 at 464.9 W kg^-1) obtained for the PPy/rGO|Ni-Co LDHs symmetrical electrode in the current study are the best reported for the two-electrode system for PPy- and LDHs-based composites. The outstanding performance in the prepared LBL film is a result of the LBL architecture of the film and the combined effect of redox reaction and electrical double layer capacitance.