engleski

The Role of Germanium Addition on the Structure and Electrical Properties of Lithium Boro-phosphate Glasses

In context of the lithium battery application and ionic conductivity enhancement, the lithium ion mobility upon addition of germanium oxide in the three series of mixed glass former lithium phosphate and boro-phosphate glasses has been investigated. The electrical conductivity of the ternary mixed glass former 40Li2O-(60-x)P2O5-xGeO2 glasses as well as quaternary (100-x)[0.5Li2O-0.1B2O3-0.4P2O5]-xGeO2 and 40Li2O–10B2O3–(50-x)P2O5–xGeO2, glasses with 0-25 mol% GeO2 have been carried out over a wide range of temperature (183-523 K) and frequency (0.01 Hz1 MHz).1, 2 The changes in dc conductivity by the addition of GeO2 at constant and simultaneously changes lithium ion concentration, is attributed to the reorganization of the glass network. In this talk, the changes in both structure and electrical properties of these glass systems and their dependence of GeO2 addition will be reported. Structure of these glasses was studied by 31P and 11B MAS NMR spectroscopy and Raman spectroscopy. 31P MAS NMR and Raman spectra reflect the depolymerization of phosphate chains by the incorporation of GeOn polyhedra. for boro-phosphate glasses 11B MAS NMR spectra reveal the formation of mixed structural units B(OP)3(OGe) in the boro-phosphate glasses and the decomposition of 11B MAS NMR spectra brings quantitative data on the number of BO3 and B(OP)3(OGe) structural units.1 This structural analysis have been combined with the impedance measurements to develop understanding of the role of GeO2 addition on the lithium ion mobility. The increase in dc conductivity with addition of GeO2 is attributed to the formation of ion conducting channels arising from the structural modification and formation of the P-O-Ge linkages, resulting in an easy migration of Li+ ions along these bonds.3 At higher GeO2 content glass network became more densely packed and ionic conductivity is slightly hindered as a consequence of the increase of bonding forces inside the network. Such a decrease in the conductivity is more reflection of the stronger cross-linkage in the glass network than that of the slight decrease in the Li+ ion concentration.

Electrical properties, Lithium boro-phosphate glass

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