Effect of Vanadium Oxide on the Structure and Li-Ion Conductivity of Lithium Silicate Glasses

A Gaddam and AR Allu and S Ganisetti and HR Fernandes and GE Stan and CC Negrila and AP Jamale and F Mear and L Montagne and JMF Ferreira, JOURNAL OF PHYSICAL CHEMISTRY C, 125, 16843-16857 (2021).

DOI: 10.1021/acs.jpcc.1c05059

The commercially ubiquitous liquid electrolytes for lithium-ion batteries have several shortcomings in terms of safety. Therefore, development of solid electrolytes, especially those that are glass- based, has been gaining increasing interest in recent times. However, the fundamental understanding of the changes in the glass structure and the corresponding changes in the properties due to the addition of dopants is necessary for the development of glasses. Therefore, here, we report a study on the role of vanadium on the glass structure, ionic conduction, crystallization behavior, and other properties of lithium silicate-based glasses (23Li(2)O-2.64K(2)O-2.64Al(2)O(3)-71.72SiO(2)) as a solid electrolyte for high-temperature Li-ion battery applications. Furthermore, we proposed a mathematical model to describe/quantify the ion-conducting channels' connectivity in glasses. The experimental glass structures were assessed using Si-29, V-51, Al-27 nuclear magnetic resonance, Fourier transform infrared, and ultraviolet-visible spectroscopy techniques. The ionic conductivity was measured by impedance spectroscopy, and the crystallization behavior was studied by optical microscopy and X-ray diffraction. Furthermore, molecular dynamics simulations were also used to gain structural insights of the glasses. In the designed compositions, the addition of vanadium decreased the overall concentration of Li+ ions. However, the results revealed that the ionic conductivity improved with the addition of vanadium in spite of a decrease in the number of charge carriers. This suggests that vanadium makes the pathways easier for the conducting ions. Thus, we conclude that vanadium modifies the conduction channels to promote better hoping of the ions from one site to another.

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