Filmes autossuportados de óxido de grafeno reduzido e polianilina decorados com nanopartículas de hexacianoferrato de níquel

Abstract

The search for more efficient and sustainable energy sources is part of technological development. In addition to the increase in demand in the production of electricity, there is a need for a more intelligent and efficient distribution, rising the importance of batteries, especially in alternative systems to Li-ion batteries. Among the various materials studied, hexacyanometalates have been highlighted in the application as cathode in batteries due to their porous structure capable of intercalating ions and storing energy and easy and low-cost synthesis. In the present work, the synthesis and characterization of a composite involving reduced graphene oxide (rGO), polyaniline (PANI), and nickel hexacyanoferrate (NiHCF) was performed. The material was synthesized as a freestanding film, using a method of gel deposition on a glass slide. After a reduction process, the film is used as a current collector for electrodeposition of NiHCF on its surface. Electrodes were prepared with 50 and 150 voltammetric electrodeposition cycles, and these materials had their electrochemical properties studied through the cyclic voltammetric (CV) technique, in which the redox behavior of the electrode was observed. The formation of NiHCF nanocubes and their interaction with the graphene-based film was identified by scanning electron microscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy and x-ray diffraction. The charge and discharge (CD) measurements showed a better performance of the electrode with 150 electrodeposition cycles, with specific capacity values from 59 mAh g-1 at 0.2 A g-1 , reaching values close to the theoretical (NiHCF ≅ 60 mAh g-1 ) in a freestanding electrode. The CD response of the half-thickness electrodes showed better capacity values (89 mAh g-1 ) and Coulombic efficiency that remained at 100% after 500 stability cycles. The capacity values achieved accredit the prepared material as a good candidate as a cathode in sodium-ion batteries, providing an alternative to lithium-ion batteries.