Micelle-Like Electrolyte Design for 4.6 V Li||NCM811 Cells Workable at 70 °C

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Localized high-concentration electrolytes (LHCE) show promise for lithium-metal batteries (LMBs) due to good anode compatibility.
• However, solvent instability at high voltages and temperatures limits current LHCE applications.
• Developing electrolytes that overcome these limitations is crucial for advancing LMB technology.

Purpose of the Study:

• To design and synthesize a novel micelle-like electrolyte (QMLE) with enhanced electrochemical and thermal stability.
• To improve the performance of lithium-metal batteries under high charging cut-off voltages and elevated temperatures.
• To present a scalable electrolyte design strategy for high-voltage and high-temperature LMBs.

Main Methods:

• Synthesized a QMLE by regulating alkyl and fluorinated segments on ethyltrimethoxysilane (ETMOS) solvents, achieving low anion-to-solvent and diluent-to-solvent ratios.
• Investigated the electrolyte's solvation properties and thermal stability through intramolecular interactions of -CF3 segments.
• Evaluated cell performance using Li||Cu and Li||NCM811 configurations under various conditions.

Main Results:

• The QMLE demonstrated improved high-temperature tolerance and facilitated anion-dominated solvation sheaths.
• Li||Cu cells achieved 98.5% coulombic efficiency at 3 mA cm⁻² and 3 mAh cm⁻².
• Li||NCM811 cells operated stably at 4.6 V and temperatures ranging from 30°C to 70°C.

Conclusions:

• The designed QMLE overcomes the limitations of traditional LHCEs for high-voltage and high-temperature applications.
• This electrolyte design strategy is versatile, scalable, and enhances the safety and performance of lithium-metal batteries.
• The study paves the way for next-generation energy storage solutions.