Formulação de tintas nanométricas funcionais de TiNb2O7

Abstract

The search for new battery materials has intensified with the aim of increasing efficiency, storage capacity, and device compactness. Among the promising anode materials, TiNb₂O₇ (NTO) stands out, as it exhibits a high theoretical capacity (~388 mAh g⁻¹), which corresponds to the maximum charge that can be stored per gram of material during charge and discharge cycles. In addition, NTO presents high cyclic stability, meaning it is capable of maintaining its performance over multiple cycles, which is essential for battery durability. However, material selection is not the only crucial factor for battery performance; manufacturing methods also play a fundamental role. Although significant advances have been achieved in recent decades, the modernization of manufacturing techniques remains underexplored due to limitations of conventional methods. In this context, 3D printing, or additive manufacturing especially through the Direct Ink Writing (DIW) technique emerges as an innovative approach for fabricating battery components, enabling the creation of miniaturized electrodes with complex geometries and high surface area, which directly contributes to the optimization of properties related to electrical conductivity and ion storage. In the DIW technique, ink formulation is a key factor in ensuring ideal printing characteristics. The lack of information about such formulations highlights the need for further research in this area. Therefore, the present work proposes the development of a functional nanometric ink for application in the DIW technique, aimed at fabricating miniaturized electrodes for lithium-ion batteries. The goal is to make the process measurable, ensure good printability, and preserve the structural properties of the printed parts after sintering. For this purpose, the resin incorporates TiNb₂O₇ (NTO) as one of its components, obtained through synthesis. A hydrothermal synthesis route was adopted to produce high-purity NTO nanoparticles, ensuring morphological control key requirements for developing good electrochemical properties. After this step, the material was calcined, and the resulting powder was used in the preparation of inks for 3D printing. The printed samples were initially evaluated dimensionally and then subjected to a sintering process. Subsequently, structural and morphological characterizations were carried out, including X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FEG-SEM). Thermal analyses such as Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) were also performed. In addition to these electrochemical analyses focused on the oxygen evolution reaction (OER) were carried out to evaluate the functional behavior of the electrodes. The results demonstrated that it was possible to obtain NTO through hydrothermal synthesis and to produce nanometric inks compatible with a modified bioprinter for electrode fabrication. The formulated resin, composed of a polyvinyl alcohol (PVA) solution and alcohol as the base, showed good printability and maintained dimensional stability of the structures after printing.