Desenvolvimento de supercapacitores utilizando Ni(OH)2/DBS

Supercapacitors are energy storage devices characterized by rapid loading and unloading cycles and long service life. To date, the best material used in this application is RuO2, but it is expensive and toxic, so one of the study objectives is to reduce the cost and toxicity of the materials used. In addition, some materials may present even more interesting characteristics for this application when synthesized at the nanoscale due to the large surface area, since the capacitance is an interface phenomenon. For this, it is possible to use ultrasonic radiation during the synthesis, since the process of acoustic cavitation generates particles in reduced scale, generating a colloidal system. In this work, colloidal suspensions of nickel hydroxide (Ni(OH)2) were obtained in the presence of sodium dodecylbenzenesulfonate (DBSNa) surfactant, and the performance of this material was studied for supercapacitor application, comparing it with Ni(OH)2 without modification. The Ni(OH)2 and Ni(OH)2/DBS-colloidal dispersions were synthesized with the aid of ultrasonic radiation, which were subjected to the zeta potential analysis, which indicated a distribution of negative charges on the surface of the particles obtained, and MET, which proved the synthesis of the nanoscale material. These dispersions were used to modify ITO electrodes using the electrophoresis technique, applying a potential difference of 1.5 V between two electrodes immersed in the dispersion synthesized for 5 or 15 minutes. In this step the electrode of interest was standardized as the positive pole. The electrodes were subjected to cyclic voltammetry and loading and discharge tests in alkaline medium. From this, the specific capacitances were calculated for each electrode and related to the respective current densities, and it was possible to calculate the retention rates for better comparison of the results (Table 1). Analyzing the values obtained, it is notable that Ni(OH)2/DBS-presented a retention rate of capacitance close to 100%, being therefore a very interesting material for this application.