Electrolyte Reactivity on the MgV <subscript>2</subscript> O <subscript>4</subscript> Cathode Surface.
In: ACS applied materials & interfaces, Jg. 15 (2023-10-18), Heft 41, S. 48072-48084
academicJournal
Zugriff:
Predictive understanding of the molecular interaction of electrolyte ions and solvent molecules and their chemical reactivity on electrodes has been a major challenge but is essential for addressing instabilities and surface passivation that occur at the electrode-electrolyte interface of multivalent magnesium batteries. In this work, the isolated intrinsic reactivities of prominent chemical species present in magnesium bis(trifluoromethanesulfonimide) (Mg(TFSI) 2 ) in diglyme (G2) electrolytes, including ionic (TFSI - , [Mg(TFSI)] + , [Mg(TFSI):G2] + , and [Mg(TFSI):2G2] + ) as well as neutral molecules (G2) on a well-defined magnesium vanadate cathode (MgV 2 O 4 ) surface, have been studied using a combination of first-principles calculations and multimodal spectroscopy analysis. Our calculations show that nonsolvated [Mg(TFSI)] + is the strongest adsorbing species on the MgV 2 O 4 surface compared with all other ions while partially solvated [Mg(TFSI):G2] + is the most reactive species. The cleavage of C-S bonds in TFSI - to form CF 3 - is predicted to be the most desired pathway for all ionic species, which is followed by the cleavage of C-O bonds of G2 to yield CH 3 + or OCH 3 - species. The strong stabilization and electron transfer between ionic electrolyte species and MgV 2 O 4 is found to significantly favor these decomposition reactions on the surface compared with intrinsic gas-phase dissociation. Experimentally, we used state-of-the-art ion soft landing to selectively deposit mass-selected TFSI - , [Mg(TFSI):G2] + , and [Mg(TFSI):2G2] + on a MgV 2 O 4 thin film to form a well-defined electrolyte-MgV 2 O 4 interface. Analysis of the soft-landed interface using X-ray photoelectron, X-ray absorption near-edge structure, electron energy-loss spectroscopies, as well as transmission electron microscopy confirmed the presence of decomposition species (e.g., MgF x , carbonates) and the higher amount of MgF x with [Mg(TFSI):G2] + formed in the interfacial region, which corroborates the theoretical observation. Overall, these results indicate that Mg 2+ desolvation results in electrolyte decomposition facilitated by surface adsorption, charge transfer, and the formation of passivating fluorides on the MgV 2 O 4 cathode surface. This work provides the first evidence of the primary mechanisms leading to electrolyte decomposition at high-voltage oxide surfaces in multivalent batteries and suggests that the design of new, anodically stable electrolytes must target systems that facilitate cation desolvation.
Titel: |
Electrolyte Reactivity on the MgV <subscript>2</subscript> O <subscript>4</subscript> Cathode Surface.
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Autor/in / Beteiligte Person: | Jeong, H ; Nguyen, DT ; Yang, Y ; Buchholz, DB ; Evmenenko, G ; Guo, J ; Yang, F ; Redfern, PC ; Hu, JZ ; Mueller, KT ; Klie, R ; Murugesan, V ; Connell, J ; Prabhakaran, V ; Cheng, L |
Zeitschrift: | ACS applied materials & interfaces, Jg. 15 (2023-10-18), Heft 41, S. 48072-48084 |
Veröffentlichung: | Washington, D.C. : American Chemical Society, 2023 |
Medientyp: | academicJournal |
ISSN: | 1944-8252 (electronic) |
DOI: | 10.1021/acsami.3c07875 |
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