Synthesis and characterization of phosphate glasses with alkaline and alkaline earth ions

• Grant number: 22/05132-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2022
• End date: May 31, 2024
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: José Fabián Schneider
• Grantee: Matheus José Ferreira
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). 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 pure solid-state Li-ion batteries is aimed at achieving devices with greater safety than liquid-electrolyte batteries, and with comparable or greater energy density. Vitreous phosphate materials offer processing advantages, good compositional homogeneity, and high ion mobility. Understanding the structure of glass and the ion diffusion process at atomic and molecular scales is fundamental to developing solid matrices with higher conductivity. The medium-range structure of the vitreous lattice determines the spatial distribution of Li jump accessible sites and the dimensionality of the ion diffusion paths. This scientific initiation project proposes the study of Li-Ca polyphosphate glasses in order to analyze the effect of Li-Ca substitution on the short and medium-range structure of the vitreous lattice. The studied compositions belong to the system (1-x-y) Li2O . x CaO . y P2O5 with y between 0.4 and 0.5 (in molar fraction) and substitution ratio Ca/(Li + Ca) between 0 and 1. An evaluation of the short-range structure around P and Li will be performed with 31P, 7Li, and 6Li nuclear magnetic resonance techniques. To analyze the medium-range structure in the phosphate network, the REINE technique (Refocused INADEQUATE Spin-Echo) will be used, to determine the mutual connectivity between the different PO4 species that form the vitreous network. The results will allow us to assess whether the behaviors of the medium-range order are linked to the ionic radius, valence or O coordination capacity of the ions present in the glass. This plan is an update of the research activities proposed in the original IC fellowship abstract presented at the time of the CEPID renewal, which proposed the study of the Li-Sr system. Due to the degree of advance of the project, we believe it is more important to consider the alkaline earth Ca.(AU)