Coordination and Diffusion in Glyoxal-Based Electrolytes for Potassium-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Potassium-ion batteries (PIBs) are an emerging energy storage technology.
• Glyoxal-based electrolytes show promise for enhancing PIB performance.
• Understanding ion coordination and transport is crucial for electrolyte optimization.

Purpose of the Study:

• Investigate the properties of potassium bis(fluorosulfonyl)imide (KFSI) in tetra-ethyl-glyoxal (TEG) electrolytes.
• Determine the coordination behavior of K+ ions with FSI anions and TEG solvent.
• Analyze ion diffusion characteristics in these novel electrolytes.

Main Methods:

• Density functional theory (DFT) calculations for energetic analysis.
• Raman spectroscopy (experimental and artificial spectra) for coordination determination.
• Impedance spectroscopy to study ion diffusion.

Main Results:

• K+ ion coordination is influenced by electrolyte composition, involving both FSI and TEG.
• Energetically favorable coordination involves the trans FSI anion and TEG solvent.
• Spectroscopic analysis shows a shift in K+ coordination from TEG to FSI with increasing concentration.
• Potassium salt diffusion is faster than lithium and sodium salts in similar electrolytes.

Conclusions:

• The coordination of K+ ions in glyoxal-based electrolytes is concentration-dependent.
• TEG-based electrolytes offer a promising avenue for high-performance PIBs.
• The faster ion diffusion in these electrolytes suggests potential for improved battery kinetics.