Ionogel-Based Electrodes for Non-Flammable High-Temperature Operating Electrochemical Double-Layer Capacitors

Area of Science:

• Materials Science and Engineering
• Electrochemistry
• Energy Storage

Background:

• Designing interfaces between nanostructured electrodes and electrolytes is crucial for high-performance electrochemical double-layer capacitors (EDLCs).
• Existing EDLCs often face limitations in charge-storage capacity, rate capability, and operational safety, particularly at elevated temperatures.
• Traditional organic electrolytes restrict the operating temperature range of EDLCs.

Purpose of the Study:

• To develop a novel and sustainable method for fabricating ionogel-based electrodes for advanced EDLCs.
• To improve the performance of EDLCs, focusing on high energy density, rate capability, and enhanced safety.
• To enable EDLCs with high-temperature and high-voltage operational capabilities.

Main Methods:

• A renewed slurry casting method was employed, replacing traditional solvents with an ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI).
• The IL was integrated directly into the electrode during slurry preparation, eliminating separate electrolyte-filling steps.
• Fabricated ionogel electrodes were used to construct symmetric EDLCs for performance evaluation.

Main Results:

• The ionogel electrodes exhibited exceptional electrolyte accessibility, leading to EDLCs with high energy density (>30 Wh/kg) and high-rate performance.
• The developed EDLCs demonstrated stable operation at temperatures up to 180°C, significantly exceeding the 65°C limit of conventional organic electrolyte-based EDLCs.
• Remarkable long-term stability was observed, with 88% capacity retention after 10,000 cycles and minimal energy density loss during extended floating tests.

Conclusions:

• The novel ionogel electrode fabrication method offers a sustainable and efficient approach for advanced EDLCs.
• These ionogel-based EDLCs show significant potential for next-generation energy storage, particularly in demanding high-temperature and high-voltage applications.
• The integrated IL approach enhances EDLC performance and safety, paving the way for robust energy storage solutions.