TlSn₂F₅, a SnF₂-based solid electrolyte with high ionic conductivity and electrochemical stability for...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Fluoride-ion batteries (FIBs) are explored as alternatives to lithium-ion batteries due to higher theoretical energy densities and better temperature stability.
• MSnF4 (M: Ba, Pb) solid electrolytes are commonly studied for room-temperature FIBs, with PbSnF4 being a leading fluoride ionic conductor but suffering from poor electrochemical stability.

Purpose of the Study:

• To develop a novel solid electrolyte for fluoride-ion batteries (FIBs).
• To investigate the potential of TlSn2F5 as a superior alternative to existing solid electrolytes.

Main Methods:

• Single-step mechanical milling was employed to synthesize TlSn2F5.
• Ionic conductivity was measured and compared to established solid electrolytes.
• DC polarization method was used for ionic transport number determination.
• 19F Nuclear Magnetic Resonance (NMR) spectroscopy was performed at various temperatures to study ion transport mechanisms.

Main Results:

• TlSn2F5 was successfully synthesized via a facile single-step mechanical milling process.
• TlSn2F5 demonstrated superior ionic conductivity compared to BaSnF4, KSn2F5, and La0.9Ba0.1F2.9.
• Ionic transport number measurements confirmed TlSn2F5 as an ionic conductor.
• 19F NMR studies revealed that increased conductivity with temperature is due to rapid fluoride ion transport.

Conclusions:

• TlSn2F5 is a promising solid electrolyte material for fluoride-ion batteries.
• The material exhibits enhanced ionic conductivity and stability, addressing limitations of current FIB electrolytes.
• Further research into TlSn2F5 could facilitate the development of advanced FIB technologies.