A Compact-Solvation Electrolyte Under Low Concentration for High-Energy Density and Stable Potassium-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Potassium-ion batteries (PIBs) require advanced electrolytes for improved energy density and stability.
• Current electrolytes often fail to meet performance demands for practical PIB applications.

Purpose of the Study:

• To introduce a compact-solvation electrolyte (CSE) strategy for high-performance PIBs.
• To investigate the effects of ionic liquid-induced solvation structures on electrolyte properties.
• To enhance the thermodynamic and kinetic performance of potassium-ion storage.

Main Methods:

• Formulation of a low-concentration (0.8 M) CSE using ionic liquid-induced solvation.
• Characterization of solvation structures, ionic conductivity, and desolvation energy.
• Electrochemical testing of graphite electrodes and Prussian blue||graphite full cells.

Main Results:

• The CSE exhibited compact, F-rich anion solvation structures, high ionic conductivity, and low desolvation energy.
• A robust KF-rich solid electrolyte interphase (SEI) formed, enhancing K+ storage.
• Graphite electrodes achieved 252 mAh g-1 reversible capacity with 99.5% Coulombic efficiency over 300 cycles.
• A full cell demonstrated 1450 cycles with 88% capacity retention.

Conclusions:

• The CSE strategy significantly advances electrolyte development for high-performance PIBs.
• This approach offers a pathway to safer and more stable potassium-ion battery technologies.
• The findings highlight the potential of tailored solvation structures for next-generation energy storage.