Filme nanocompósito entre nanotubos de carbono e hexacianoferrato de cobalto como alternativa de catodos para baterias de inserção de íons alumínio

Abstract

Clean, sustainable, and efficient technologies have been driving thin-film-based electronic applications for the development of new lightweight and portable batteries, focusing on the establishment of electrodes that play crucial roles in the next generation of energy storage devices. Prussian blue analogues (PBA) and carbon nanotubes (CNT) have been increasingly investigated as alternative components for energy storage devices. The combination of desirable properties, such as the redox behavior and interstitial sites of PBA, along with the high surface area and electrical conductivity of CNT, results in promising nanocomposites for the advancement of ion-intercalation batteries. This study aimed at the synthesis and characterization of cobalt hexacyanoferrate/carbon nanotube (HCFCo/CNT) nanocomposite films, ultimately investigating their electrochemical performance in aluminum ion intercalation in aqueous electrolytes. The material was synthesized using the liquid/liquid interfacial method, in which precursor solutions of HCFCo were added to CNT dispersions in toluene. The nanocomposite film was characterized using X-ray diffraction, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy, which confirmed the formation of the proposed material, as well as the distribution of HCFCo particles within the CNT network. For the electrochemical study, a three-electrode cell was assembled using 0.1 mol L⁻¹ AlCl₃ as the supporting electrolyte, with the film deposited onto a carbon electrode as the working electrode. The material exhibited a specific capacity of 94.74 mA h g⁻¹ with a retention of 78% after 10 cycles at a current density of 0.04 A g⁻¹ (0.5C). The cathode retained 77.7% of its initial capacity after 500 cycles at 1.62 A g⁻¹ (2C). In the test with varying current densities, the specific capacity values obtained were 97.67, 82.88, 75.04, and 64.63 mA h g⁻¹ for 0.04, 0.8, 1.62, and 4.0 A g⁻¹, respectively, with a retention of 66%. The synthesis method proved to be efficient, resulting in promising electrodes as cathodes for aqueous Al³⁺-ion batteries, demonstrating the potential of the HCFCo/CNT nanocomposite film as a material for the development of lighter, safer, translucent, flexible, environmentally friendly, and cost-effective batteries.