Probing a battery electrolyte drop with ambient pressure photoelectron spectroscopy

Area of Science:

• Materials Science
• Electrochemistry
• Surface Science

Background:

• Probing the electrode/electrolyte interface is crucial for understanding lithium-ion battery functionality.
• Conventional photoelectron spectroscopy is limited in analyzing realistic battery environments.
• Operando ambient pressure photoelectron spectroscopy offers a novel approach.

Purpose of the Study:

• To characterize a model battery electrolyte using ambient pressure photoelectron spectroscopy (APPES).
• To demonstrate APPES for analyzing liquid electrolytes in their native state.
• To investigate the composition of the electrolyte surface and bulk.

Main Methods:

• Ambient pressure photoelectron spectroscopy (APPES) was employed.
• A model electrolyte of 1M lithium bis(trifluoromethane)sulfonimide in propylene carbonate was used.
• Solvent vapor was utilized to stabilize the liquid phase for analysis.

Main Results:

• Successfully obtained APPES data for liquid-phase propylene carbonate.
• Differentiated between salt and solvent contributions to the spectra.
• Observed accumulation of ionic species at the electrolyte surface, distinct from the bulk.
• Characterized electrolyte composition changes with probing depth.

Conclusions:

• Direct measurement of complex liquids like battery electrolytes is feasible using APPES.
• This advancement is critical for true operando studies of lithium-ion batteries.
• The findings provide insights into electrolyte behavior at the interface.