Preparation of sodium ion conductive glass ceramics with NASICON structure containing Sc

• Grant number: 17/24531-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2018
• End date: September 30, 2019
• Field of knowledge: Engineering - Materials and Metallurgical Engineering
• Principal Investigator: Ana Candida Martins Rodrigues
• Grantee: Lucas de Almeida Silva
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID

Abstract

The development of high-performance batteries is of utmost importance for the advancement of the electronics, communication and information industries. However, for the development and optimization of their performance, aspects related to cost, safety, recyclability and efficiency should be improved. Electrolytes are essential components to batteries with great influence, for example, in their useful life. Liquid electrolytes can cause various problems in batteries, such as leaks or internal short circuits, which cause accidents. Thus, batteries with solid electrolytes are the safest alternative, as they are leak proof and non-flammable. An important class of solid electrolytes are those with Nasicon structure. In fact, the structure Nasicon, acronym of Sodium Super Ionic Conductor is composed of tetrahedra (PO4) joined by vertices to octahedros AO6 where A is an element in octahedral coordination, for example, Zr, Ti and Ge. This sequence of vertex-joined tetrahedra and octahedra creates three-dimensional channels in which the alkaline ion can move. The generic formula of the Nasicon compounds can be written as: AxM'xM2-x (PO4) 3, where A is an alkaline ion, M is a 4+ or 3+ valence transition metal and M 'is a transition metal with 3+ valence. Due to the possibility of replacing cations, especially M4 + by M3 + cations, this structure accepts a large number of chemical elements in a wide range of solid solutions. Nasicon sintered materials have become attractive for use as solid electrolytes because of their good chemical stability and high ionic conductivity. However, often the synthesis by the classical route of reaction in solid state followed by sintering, leads to materials with high porosity. On the other hand, the synthesis of these materials by the glass ceramic route, known since the pioneering works of J. Fu (1997), leads to materials with low porosity, a characteristic that, according to this author, is the main advantage of glass ceramics. Recently, the synthesis, through the solid state reaction, of a Nasicon compound containing scandium (Sc), and high ionic conductivity (Ã Na = 6.9 x 10-4 S.cm -1 at 25 ° C) has been reported in the literature. Thus, the main objective of the present project of Scientific Initiation, is to alter the processing of obtaining the solid electrolyte containing Sc. We propose the use of the "glass crystallization" route to obtain a glass ceramic with a NASICON structure containing the scandium element (Sc) in place of the M ion to obtain a material with dense microstructure and high ionic conductivity. The structural characterization will be performed by X-ray diffraction to identify the phases. The microstructural characterization will be performed by scanning electron microscopy. The electrical characterization will be performed by the Impedance Spectroscopy (EI) technique, over a wide temperature range, in order to obtain, in addition to ionic conductivity values at a certain temperature, conduction activation energy. (AU)