Dual effect of structure and hydration on magnesium-ion insertion into electrodeposited V2O5 thin films
Lee, Sang Bok
Lee, Sang Bok
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As global energy needs continue to increase, there is a growing demand for next-generation storage technologies that confer high energy density. Lithium-ion battery technologies, the current state of the art, possess a number of limitations that prevent further performance enhancement and safe use. Owing to magnesium's abundance, safety, and high volumetric capacity; magnesium-ion batteries are promising alternatives to lithium-ion storage devices. However, a number of challenges have impeded progress in magnesium-ion battery research, such as magnesium anode passivation and poor magnesium-ion insertion kinetics into traditional metal oxide cathode materials. This research addresses the latter of the two problems by further investigating a well-known potential cathode material for magnesium-ion batteries. Vanadium (V) Oxide, a transition metal oxide with flexible interlayer spacing, has been shown to reversibly intercalate Mg2+ ions with high capacity in its crystalline form. However, new research suggests that amorphous V2O5 cathodes might offer greater capacity for Mg-ion insertion owing to increased void space for monovalent and multivalent ion insertion. In this work, we use two primary electroanalytical techniques--cyclic voltammetry and galvanostatic voltammetry--to systematically investigate the impact of structure, crystallinity, and hydration on the electrochemical performance of electrodeposited V2O5 thin films. Ultimately, our findings suggest that it is structural hydration, rather than film crystallinity, that primarily determines Mg-ion insertion capacity of V2O5 thin films.