Solvent-in-Salt Electrolytes for Fluoride Ion Batteries

Area of Science:

• Energy Storage
• Electrochemistry
• Materials Science

Background:

• Fluoride ion batteries (FIBs) offer high theoretical energy density and utilize abundant materials.
• Room-temperature cycling of FIBs is hindered by unstable and poorly conductive electrolytes.
• Developing stable electrolytes is crucial for advancing FIB technology.

Purpose of the Study:

• To investigate solvent-in-salt electrolytes for room-temperature fluoride ion battery operation.
• To identify electrolytes with enhanced electrochemical stability and improved cycling performance.
• To understand the fundamental solvation structure and transport properties of novel electrolytes.

Main Methods:

• Exploration of various solvents in salt electrolytes for FIBs.
• Electrochemical characterization to determine stability windows and cycling performance.
• Spectroscopic and computational methods to analyze electrolyte solvation and transport.

Main Results:

• Aqueous cesium fluoride demonstrated high solubility and an enhanced electrochemical stability window of 3.1 V.
• The developed electrolyte suppressed active material dissolution, leading to improved cycling stability.
• Investigated solvation structure and transport properties provided insights into electrolyte performance.

Conclusions:

• Solvent-in-salt electrolytes, particularly aqueous cesium fluoride, are viable for room-temperature fluoride ion batteries.
• This approach enhances electrochemical stability and cycling performance, overcoming previous limitations.
• Further research into electrolyte properties can optimize FIB performance for practical applications.