Síntese de óxido de grafeno e niobato de estanho para construção de supercapacitores e baterias

Abstract

There is currently a growing demand for new energy generation and storage technologies, mainly due to the rising cost and scarcity of fossil fuels, concerns about climate change, and the adoption of greener and more sustainable consumption habits. The development of storage devices such as batteries and supercapacitors is essential to overcome the challenges of the energy transition. In this paper, we present the production and application of two new materials for energy storage: graphene oxide obtained through the electrochemical exfoliation of graphite, and tin niobate. Graphene oxide can be produced with a yield of 4 g per hour using low-cost reagents and equipment. Furthermore, this work developed a method for purifying graphene oxide. The graphene oxide exhibited an ID/IG ratio of 0.87 ± 0.01, corresponding to multilayer graphene. This material can be used as an active material for supercapacitor electrodes, presenting a storage capacity of 11 F g-1 when subjected to a current density of 150 mA g-1. Tin niobate (Sn2Nb2O7), in turn, was synthesized hydrothermally in acidic and alkaline media; both products were used as active materials for sodium-ion batteries. Tin niobate obtained in an acidic medium presented a storage capacity of 120 mAh g-1, while that obtained in an alkaline medium presented a capacity of 60 mAh g-1 when subjected to a current density of 50 mA g-1. The sodium-ion batteries were tested using two types of electrolyte and subjected to four current densities. The batteries with the best performance were those using diglyme as a solvent and electrodes containing tin niobate synthesized in an acidic medium.