Chloro-Functionalized Ether-Based Electrolyte for High-Voltage and Stable Potassium-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Ether-based electrolytes offer good low-temperature performance and high ionic conductivity for potassium ion batteries (PIBs).
• Dilute ether-based electrolytes suffer from ion-solvent co-intercalation, poor cycling stability, and low oxidative stability, limiting their use with high-voltage cathodes (>4.0 V).
• Aluminum current collector corrosion is a significant issue in PIBs.

Purpose of the Study:

• To enhance the oxidative stability and solid-electrolyte interphase (SEI) formation in ether-based electrolytes for PIBs.
• To improve the cycling stability and high-voltage performance of PIBs.
• To enable long-lasting and wide-temperature operation of PIBs.

Main Methods:

• Introduction of chloro-substitution (an electron-withdrawing group) into ether-based electrolytes.
• Preparation of dilute (~0.91 M) chloro-functionalized ether-based electrolytes.
• Electrochemical testing of K||graphite, K||Prussian blue (PB), and PB||graphite full-cells.

Main Results:

• The chloro-functionalized electrolyte facilitated the formation of a homogeneous dual halides-based SEI.
• The functionalized electrolyte effectively suppressed aluminum corrosion at high voltage.
• K||graphite cells showed 700 cycles, K||PB cells (4.3 V) showed 500 cycles, and PB||graphite full-cells demonstrated 6000 cycles with 99.98% average Coulombic efficiency.
• PB||graphite full-cells operated stably between -5°C and 45°C.

Conclusions:

• Electrolyte functionalization via chloro-substitution significantly enhances the electrochemical performance of ether-based electrolytes in PIBs.
• The modified electrolytes provide long-lasting cycling, high Coulombic efficiency, and wide-temperature operability.
• This approach offers a promising strategy for developing advanced potassium ion batteries.