Cyclic Ether-Based Electrolyte with a Weak Solvation Structure for Advanced Potassium Metal Batteries.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Potassium metal batteries (PMBs) are crucial for large-scale energy storage.
• Current carbonate electrolytes lack stability with potassium anodes.
• Linear ethers offer potassium compatibility but have poor oxidation stability for high-voltage cathodes.

Purpose of the Study:

• To design a novel electrolyte for improved potassium metal battery performance.
• To enhance the stability of the potassium-metal interface and solid-electrolyte interphase (SEI).
• To enable the use of high-voltage cathodes in PMBs.

Main Methods:

• Proposed a weakly solvating cyclic ether as a solvent for a new electrolyte.
• Investigated the electrolyte's anion-dominated solvation structure.
• Utilized atomic force microscopy to examine the mechanical properties of the SEI.

Main Results:

• The new electrolyte facilitated the formation of an inorganic-rich SEI layer.
• The SEI exhibited superior mechanical properties, preventing fracture.
• Achieved highly reversible potassium metal plating/stripping for 1300 hours with 99.20% average Coulombic efficiency.
• Demonstrated stable full cells with high-voltage cathodes under harsh conditions.

Conclusions:

• Weakly solvating electrolytes (WSEs) based on cyclic ethers are effective for stabilizing the K-metal interface.
• The developed WSE enables robust SEI formation, crucial for long-duration PMB operation.
• This work provides a new avenue for designing advanced electrolytes for high-performance PMBs.