Engineering oxygen-deficient nanocomposite comprising LaNiO3-δ and reduced graphene oxide for high-performance pseudocapacitors

Abstract

Aiming at a high performance pseudocapacitive electrode - an oxygen-deficient nanocomposite comprising reduced graphene oxide-Lanthanum nickelate LaNiO3 (rGO-LNO) was synthesized using a facile binder-free approach. The structural identity and the phase purity of the nanocomposite were verified by X-ray diffraction and electron microscopy studies coupled by the inputs from Raman scattering. The assistance of rGO in the amplification of oxygen vacancies in rGO-LNO relative to LNO was confirmed from X-ray photoelectron spectroscopy (XPS). Maximum specific capacitance of 920 F g−1 at 1 A g−1 current density in 6 M KOH solution in a three-electrode set up was observed. An excellent long-term cycling efficiency of over 99 % even at a high current density of 10 A g−1 in solid-state-symmetrical setup. Analysis of self-discharge and leakage current parameters concluded sturdy electrode dynamics. Deconvolutions of cyclic voltammograms were suggestive of majorly bulk conduction over diffusive kinetics. In summary, LNO facilitates a faster electron transfer rate and while rGO allows the penetration of the electrolytes into the bulk matrix, and allows more effective utilization of the electrode materials via. an efficient ion-exchange.