Níbio como metal aditivo para modificação de aerogel à base de nanocelulose carbonizada para potencial aplicação como eletrodos em supercapacitores

Abstract

This work presents the development and characterization of carbonized nanocellulose aerogels synthesized with transition metals, aiming at their application as electrodes for supercapacitors. The proposal seeks more sustainable and environmentally safe alternatives to conventional materials, such as cobalt, by exploring niobium pentoxide (Nb2O5) as a functional additive. The aerogels were obtained from nanocellulose dispersions with different metallic precursors (Nb2O5 CG, Nb2O5 AG, and cobalt acetate), through gelation, solvent exchange with tert-butyl alcohol, freeze-drying, and carbonization at 800 °C. Structural (FTIR, XRD, Raman), morphological (SEM/EDS), and textural (BET/BJH) characterizations confirmed the formation of a porous matrix with amorphous structure and effective metal incorporation. Electrochemical analyses revealed that synthesis with Nb2O5 CG Nano T resulted in the best performance, reaching a specific capacitance of 106.8 F·g-¹, energy density of 0.064 Wh·kg-¹, and power density of 1.07 W·kg-¹. The samples synthesized with Nb2O5 AG Nano T and Cobalt Acetate also showed superior performance compared to the control sample (without metals), which exhibited only 11.3 F·g-¹. Galvanostatic charge-discharge tests and electrochemical impedance spectroscopy confirmed lower internal resistances and higher efficiency in the metal-containing samples. The results demonstrate that metal synthesis with Nb2O5 is effective in improving capacitive performance, positioning the developed aerogels as promising candidates for energy storage devices with reduced environmental impact. [resumo fornecido pelo autor]