Deep Eutectic Solvent-Dominant Crosslinked Polymer Electrolytes Enabling Efficient Chloride-Ion Transport via...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) are crucial for advancing chloride ion batteries (CIBs) by addressing issues like electrode dissolution and volume changes.
• However, achieving high ionic conductivity and robust electrochemical stability in SPEs remains a significant challenge for practical CIB applications.

Purpose of the Study:

• To develop a synergistic strategy for creating advanced SPEs by combining a tailored deep eutectic solvent (DES) with a crosslinked polymer network.
• To overcome the limitations of existing SPEs in terms of ionic conductivity and electrochemical stability for CIBs.

Main Methods:

• A novel DES was synthesized by tailoring the cation structure of chloride salts, specifically using tributylmethylammonium chloride with succinonitrile for enhanced Cl- dissociation.
• This DES was incorporated into a crosslinked ethoxylated trimethylolpropane triacrylate (ETPTA) polymer network to form flexible, self-standing SPE films.
• The electrochemical performance of the optimized ETPTA3-DES7 SPE was evaluated in symmetric and full CIB cells.

Main Results:

• The optimized ETPTA3-DES7 SPE demonstrated a record-high room-temperature ionic conductivity of 6.54 × 10-4 S cm-1.
• The SPE exhibited significantly improved electrochemical stability compared to the pristine DES.
• The developed SPE enabled high reversible capacities, excellent rate capability, and stable cycling in CIBs, even at sub-ambient temperatures (0 °C).

Conclusions:

• The synergistic combination of a tailored DES and a crosslinked polymer network effectively enhances ionic conductivity and electrochemical stability in SPEs for CIBs.
• The flexible and stable SPE films show great promise for practical applications, as evidenced by their reliable performance in prototype pouch cells under various conditions.
• This work presents a viable pathway towards developing safer and more efficient chloride ion battery technologies.