Transient Polarized Cavities Mediate an Ultrafast and Stable Graphite Anode for Potassium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional ester-based electrolytes for potassium-ion batteries (PIBs) face limitations like freezing at room temperature and graphite exfoliation, hindering performance.
• Propylene carbonate, a common electrolyte component, leads to poor rate capability and structural degradation in graphite anodes.

Purpose of the Study:

• To overcome the limitations of conventional electrolytes in PIBs by designing a novel dipole-engineered electrolyte.
• To investigate a new ion transport mechanism involving transient polarized cavities for enhanced potassium-ion kinetics.
• To enable stable and reversible potassium-ion (de)intercalation in graphite anodes.

Main Methods:

• Design and synthesis of a dipole-engineered electrolyte.
• Investigation of K+ desolvation and cavity formation using electrochemical techniques.
• Fabrication and testing of K||graphite half-cells to evaluate electrochemical performance.

Main Results:

• The engineered electrolyte facilitates the formation of transient polarized cavities, lowering the ion transport barrier for K+.
• A stable, ion-conductive solid electrolyte interphase (SEI) is formed on the graphite anode.
• The K||graphite half-cell achieved a high capacity of 290 mAh g-1 at 50 mA g-1 with over 1000 cycles and retained 226 mAh g-1 at 500 mA g-1.

Conclusions:

• A cavity-mediated ion transport mechanism was revealed, offering a new strategy for designing advanced electrolytes.
• The developed electrolyte enables high-rate and long-life graphite anodes for potassium-ion batteries.
• This work provides critical insights for the development of next-generation energy storage systems.