Strongly Solvating Ether Electrolytes for High-Voltage Lithium Metal Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Battery Technology

Background:

• Ethers are favored electrolytes for lithium metal batteries (LMBs) due to their stability with lithium metal.
• Current research focuses on anion-enriched solvation structures to enhance electrochemical stability, yet an anodic bottleneck persists.
• Oxidation stability in ether electrolytes is a critical challenge for high-energy-density applications.

Purpose of the Study:

• To investigate the correlation between electrolyte solvation structure and oxidation stability in ether-based electrolytes for LMBs.
• To identify electrolyte design principles that overcome the anodic limitations of current ether systems.
• To enhance the performance of Ni-rich cathodes operating at ultrahigh voltages.

Main Methods:

• Systematic study of linear ether electrolytes with varying Li+ solvation energies.
• Electrochemical testing of electrolytes on Ni-rich cathodes at 4.7 V.
• Analysis of electrolyte solvation dynamics and interfacial stability.

Main Results:

• Triglyme (G3)-based electrolytes with the highest Li+ solvation energy exhibited superior stability on Ni-rich cathodes.
• Achieved 93% capacity retention after 100 cycles at an ultrahigh voltage of 4.7 V.
• Demonstrated that stronger Li+ solvating ability suppresses deleterious oxidation side reactions by reducing free ether molecule lifetime.

Conclusions:

• Stronger Li+ solvation in ether electrolytes is key to improving oxidation stability and overcoming anodic bottlenecks.
• Optimizing solvation structure offers a promising strategy for developing high-efficiency electrolytes for high-energy-density LMBs.
• This research provides critical insights into solvation dynamics for advanced battery electrolyte design.