Methodologies for Operando ATR-IR Spectroscopy of Magnesium Battery Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Spectroscopy

Background:

• Organoaluminate electrolytes are promising for magnesium (Mg) batteries.
• Operando spectroscopic techniques are crucial for understanding electrolyte behavior during battery operation.
• Attenuated total reflection infrared (ATR-IR) spectroscopy offers in-situ analysis capabilities.

Purpose of the Study:

• To assess the suitability of operando ATR-IR spectroscopy for studying organoaluminate electrolytes.
• To compare two distinct spectroelectrochemical cell configurations for Mg battery electrolyte analysis.
• To identify the impact of working electrode arrangement on ATR-IR measurements.

Main Methods:

• Utilized operando attenuated total reflection infrared (ATR-IR) spectroscopy.
• Employed an exemplar organoaluminate electrolyte: the "all-phenyl complex" ([Mg2Cl3·6THF]+[AlPh4]−) in tetrahydrofuran (THF).
• Compared two spectroelectrochemical cell designs: one with a Pt gauze working electrode and another with a thin Pt film deposited on the ATR crystal.

Main Results:

• Significant differences were observed in the ATR-IR spectral response between the two cell configurations.
• The observed spectral variations are attributed to the different spatial relationships between the working electrode and the ATR sampling volume.
• The study highlights how electrode placement influences the spectroscopic data obtained.

Conclusions:

• Operando ATR-IR spectroscopy is a viable technique for studying Mg battery electrolytes.
• The choice of spectroelectrochemical cell configuration and electrode placement critically affects the obtained spectral data.
• Careful consideration of cell design is necessary for accurate in-situ characterization of organoaluminate electrolytes using ATR-IR.