Deep Eutectic Electrolytes Enable Anion-Derived Interfaces for High-Temperature Sodium-Ion Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional sodium-ion batteries (SIBs) face high-temperature instability due to electrolyte decomposition and interphase issues.
• Developing thermally robust electrolytes is crucial for advancing SIBs for large-scale applications.

Purpose of the Study:

• To design and synthesize a stable deep eutectic electrolyte for high-temperature SIBs.
• To investigate the electrolyte's impact on interfacial stability and electrochemical performance.

Main Methods:

• Synthesis of a deep eutectic electrolyte (NPST) using sodium bis(fluorosulfonyl)imide and prop-1-ene-1,3-sultone.
• Characterization of thermal and electrochemical stability.
• Analysis of interfacial properties using X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry.

Main Results:

• NPST exhibits exceptional thermal and electrochemical stability.
• The electrolyte promotes an inorganic-rich anion-derived interfacial phase, suppressing decomposition and metal dissolution.
• Uniform sodium deposition and suppressed dendrite growth were observed.
• SIB full cells with NPST retained 91.5% capacity after 3000 cycles at 60°C.

Conclusions:

• Engineering deep eutectic electrolytes is a viable strategy to overcome electrolyte instability in high-temperature SIBs.
• NPST offers a promising solution for next-generation interfacial design in sodium-ion batteries.