Inhibiting Graphite Co-Intercalation through Weak Solvating Ether Electrolytes for Stable Cycling in Potassium-Ion...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ether-based electrolytes are crucial for stable solid electrolyte interfaces (SEIs) in anodes.
• Conventional ethers cause cation-solvent co-intercalation in graphite, reducing capacity and increasing voltage.
• This phenomenon limits the performance of graphite anodes in potassium-ion batteries.

Purpose of the Study:

• To develop weakly solvating ether solvents to suppress cation-solvent co-intercalation.
• To investigate tetrahydrofuran (THF) as a weakly solvating solvent for potassium-ion battery electrolytes.
• To enhance the stability and capacity of graphite anodes in potassium-ion batteries.

Main Methods:

• Theoretical calculations to determine K+-solvent binding energies.
• Electrochemical testing of potassium-ion batteries with THF-based electrolytes.
• Analysis of SEI formation and anode stability.

Main Results:

• Tetrahydrofuran (THF) showed significantly lower K+-solvent binding energy (-0.89 eV) compared to DME (-1.37 eV) and EC (-1.26 eV).
• A 1 M K salt solution in THF suppressed co-intercalation, electrolyte decomposition, and graphite exfoliation.
• The THF-based electrolyte facilitated a uniform SEI, achieving 99% capacity retention in graphite anodes over 200 cycles.
• The electrolyte demonstrated adaptability with both hard and soft carbonaceous anodes.

Conclusions:

• Weakly solvating ether electrolytes effectively suppress cation-solvent co-intercalation in graphite anodes.
• THF-based electrolytes offer a promising solution for high-capacity and stable graphite anodes in potassium-ion batteries.
• This research advances the application of graphite anodes in potassium-ion batteries by optimizing electrolyte design.