Ultrafast Cointercalation Chemistry for Low-Temperature Sodium-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are a sustainable energy storage solution, but their performance degrades significantly in cold environments.
• Graphite anodes in SIBs face challenges with cointercalation chemistry at low temperatures, primarily due to desolvation issues.

Purpose of the Study:

• To investigate the overlooked desolvation behavior affecting SIB performance at low temperatures.
• To develop a novel electrolyte system that enhances the kinetics of cointercalation chemistry in SIBs under cold conditions.

Main Methods:

• Proposed a two-step reaction mechanism involving partial desolvation and interlayer diffusion.
• Developed a dual-solvent electrolyte with varying solvation strengths.
• Utilized solid-state nuclear magnetic resonance (ss-NMR) for verification.

Main Results:

• Identified a novel two-step reaction mechanism explaining low-temperature performance decay.
• The dual-solvent electrolyte facilitated rapid partial desolvation and interlayer diffusion.
• Achieved ~90.0% capacity retention at -30 °C (1 C) and ~84% rate performance from 0.1 to 5 C at -30 °C.

Conclusions:

• The developed dual-solvent electrolyte effectively overcomes low-temperature performance limitations in SIBs.
• This approach enhances the viability of SIBs for large-scale energy storage in cold climates.
• The findings provide critical insights into optimizing SIB electrolytes for extreme temperature applications.