To demonstrate the critical importance of electrode/electrolyte stability in rechargeable aluminum (Al) batteries, the chemical compatibility between vanadium(V) oxide (V2O5), a proposed cathode material for Al batteries, and the common chloroaluminate-containing ionic liquid electrolytes is investigated. We reveal that V2O5 reacts with both the Lewis acidic (Al2Cl7-) and the Lewis neutral species (AlCl4-) within the electrolyte. The resulting decomposition products are studied using a combination of electrochemical analyses, Raman spectroscopy, solution-state and solid-state nuclear magnetic resonance (NMR) spectroscopy, and density functional theory (DFT). The results establish that V2O5 chemically reacts with Al2Cl7- to form vanadium(V) oxychloride (VOCl3) and an amorphous aluminum oxide precipitate. V2O5 also chemically reacts with AlCl4- to produce dioxovanadium chloride (VO2Cl) and a new anionic species of metavanadate coordinated with aluminum chloride (AlCl3VO3-), which furthermore exhibits electrochemical redox activity between V(V) and V(II). Our experimental results have significant implications when interpreting the electrochemical properties and mechanisms of rechargeable Al-V2O5 batteries.

Electrode/electrolyte compatibility in rechargeable aluminum batteries: Chemical reactions and electrochemical properties between chloroaluminate ionic liquids and vanadium pentoxide

2019 Fall National Meeting

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