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O trabalho visa dispor sobre os resultados do estudo das características eletroquímicas de supercapacitores operando com eletrólito à base de líquido iônico de baixa toxicidade, considerando a influência da temperatura de operação e do potencial nominal máximo nas propriedades eletroquímicas de supercapacitores como indicadores da estabilidade eletroquímica do eletrólito empregado nestes dispositivos. Foi utilizado eletrodo comercial de carbono ativado, combinado em várias proporções molares, eletrólito a base de glicerol e KOH e sais de ChCl e K2CO3. Na primeira parte sem o revestimento do coletor de corrente acoplado com fio de níquel, e na segunda parte com revestimento do coletor de corrente acoplado com fio de platina com tinta sintética inoxidável e inerte. Os supercapacitores com eletrólitos de líquido iônico foram comparados com supercapacitores em eletrólitos que utilizam solução aquosa KOH e eletrólito orgânico, verificando a estabilidade e o comportamento dos supercapacitores entre a temperatura ambiente e a 80 °C. Ademais, foi avaliada a influência do tipo de eletrólito na capacidade de armazenamento e resistência interna em série (ESR) dos supercapacitores. As propriedades elétricas foram investigadas em um analisador eletrônico computadorizado com disponibilidade para testes de ciclos galvanostático e voltametria cíclica, determinando a capacitância específica e resistência interna. Foram realizados, também, microscopia eletrônica de varredura (MEV) e difração de raios X (DRX). As taxas de varredura de voltametria variaram de 1 a 30 mV s-1. Uma taxa de varredura mais baixa levou a uma capacitância específica mais alta com um potencial máximo aplicado de 2,1 V, tanto para os eletrólitos LIs à temperatura ambiente quanto para 80 °C. Além do aumento das concentrações molares dos eletrólitos e a elevação da temperatura do sistema para 80 °C em relação à temperatura ambiente levou a um maior valor de capacitância específica. No geral, o método do ciclo galvanostático teve um aumento na densidade de corrente elétrica, enquanto o tempo de carga e descarga diminuiu. The present work aims to provide on the results of the study of the electrochemical characteristics of supercapacitors operating with electrolyte based on low toxicity ionic liquid, considering the influence of operating temperature and maximum nominal potential on the electrochemical properties of supercapacitors as indicators of electrochemical stability of the electrolyte employed in these devices. Commercial activated carbon electrode was used, combined in various molar proportions, glycerol-based electrolyte with KOH, ChCl and K2CO3 salts. In the first part without the coating of the current collector coupled with nickel wire, and in the second part with coating of the current collector coupled with platinum wire with stainless and inert ink. Supercapacitors with ionic fluid electrolytes were compared with electrolyte supercapacitors using KOH aqueous solution and organic electrolyte, verifying the stability and behavior of supercapacitors between room temperature and 80 °C. Furthermore, the influence of electrolyte type on storage capacity and serial internal resistance (ESR) of supercapacitors was evaluated. The electrical properties were investigated in a computerized electronic analyzer with availability for tests of galvanostatic cycles and cyclic voltammetry, determining the specific capacitance and internal resistance. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were also performed. Voltammetry scan rates ranged from 1 to 30 mV s-1. A lower scanning rate led to a higher specific capacitance with a maximum applied potential of 2.1 V, both for LIs electrolytes at room temperature and at 80 °C. In addition to the increase in the molar concentrations of electrolytes and the increase of the system temperature to 80 °C in relation to the ambient temperature led to a higher value of specific capacitance. In general, the galvanostatic cycle method had an increase in the density of electric current, the time of loading and discharge decreased.

Due to the remarkable properties of graphene oxide (GO) and its possibility of functionalization, GO has been used in many applications such as nanocomposites. GO nanosheets have been shown to improve the properties of the polypropylene (PP) matrix, for instance, its strength, gas barrier, thermal, and electrical conductivity. As PP has relatively low cost and varied applications, this work aims to study the changes in its thermal, morphological, and mechanical properties, due to the incorporation of GO in the PP matrix. GO was synthesized from graphite by a modified Hummers method. The nanocomposites PP/GO with 0.1, 0.2, and 0.3 wt% of GO in the PP matrix were obtained using a twin-screw extruder and an injection molding machine via a melt blending process. The nanocomposites PP/GO were characterized by FE-SEM and Izod impact test. In addition, the GO nanosheets were also characterized by Raman spectroscopy, ATR-FTIR, FE-SEM, and XRD, therewith correlation between properties was discussed.