Synthesis and Characterizations of Modified Vanadium Glass Electrodes for Use in Lithium-Ion Batteries
Authors: Kindle Michael , Song Min-Kyu , McCloy John 
Published: February 2020

The desire for energy storage technologies with higher specific energy densities is becoming critical to industries and society, especially for electric vehicles and grid energy storage of intermittent renewable energy. Glass cathodes can have a capacity between 150-500 mAh/g and can be typically created in facile single-step melt quench procedures making them scalable and cost-effective1-3. Glasses-based electrodes have exhibited improved performance, both in capacity and rate capability, compared to their crystalline counterparts for several systems containing iron and vanadium1-4. The increased performance in the glass system is primarily linked to the irreversible loss that occurs from a crystalline phase change which does not occur in the glassy material1,4. Various iron and vanadate modified glass systems have been investigated. However, a more detailed analysis of the effect of alkali borates and how they alter the glass system has not been carried out; this study is investigating the effects of altering the content of lithium borate to modify the boron coordination, and thus the boron superstructures and non-bridging oxygen(NBO) sites that form. These boron superstructures, as well as the NBO sites, can significantly alter the overall glass structure and properties2,5. The LixByO(x+3y)/2:V2O5 system is under study for a potential cathode material. From literature, the LiBO2-V2O5 glass system showed a promising specific capacity of ~400 mAh/g and excellent stability over 100 cycles1. However, the mechanism of the enhanced performance over its crystalline counterpart (V2O5), beyond the lack of crystalline phase change, has not been analyzed. On top of that, it has not been fully understood why the improved performance over pure amorphous V2O5, and other modified phosphate and transition metal vanadium glasses occurs3,6,7. Alkali borates, including lithium, exhibit a wide range of boron structures and NBO sites as the composition is altered, which will allow for a well-understood binary glass system in the form of a lithium borate to investigate the structure-property relationship of vanadium-based glass materials as potential cathode materials5. Impedance data, FTIR, Raman spectroscopy and battery cycling data will be analyzed to relate ionic conductivity, electrochemical performance, and glass structure as the alkali borate content changes.

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