V2O5 was used as a model system to developed understanding of critical parameters that govern intercalation and de-intercalation of multiple transporting ions in layered oxide materials, in particularly focusing on the role of the water and defects. Electrochemical synthesis of bilayered V2O5 results in incorporation of structural hydroxyl groups, typical for electrochemically synthetized oxides in aqueous media. 1H magic angle spinning NMR spectroscopy was performed to investigate differences in the proton environments between sol-gel and EC-V2O5. Comparisons of the two NMR spectra (Figure 1) reveal distinct chemical environment at 8.8 ppm that is only observed in the EC-V2O5 material. The existence of this feature is consistent with the presence of a more strongly-bound OH species and clearly indicates a structural component that is not found in sol-gel material. Using both in situ and ex situ characterization methods, we demonstrated that structural OH species are highly stable and persist in the structure during reversible cycling. This understanding has broad implications for improving the performance of a variety of hydrated oxide systems, and indicates that the formation of covalently-bound hydroxoxide species can ultimately enable the design of optimal structures that can operate with multiple transporting ions with higher capacity and dramatically improved cycle life performance.

Role of structural hydroxyl groups in enhancing performance of electrochemically-synthesized bilayer V2O5

256th National Meeting (2018)

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