Thermoresponsive ether-based electrolyte for wide temperature operating lithium metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Safe and efficient electrolytes are critical for lithium metal batteries (LMBs).
• Conventional electrolytes struggle to balance redox stability, ion transport, and safety across wide temperature ranges.
• Achieving simultaneous improvements in these properties remains a significant challenge in battery technology.

Purpose of the Study:

• To develop a novel ether-based thermoresponsive electrolyte for lithium metal batteries.
• To enable stable operation over a broad temperature window (-60 to 60°C).
• To enhance interfacial stability, ion transport kinetics, and high-temperature safety.

Main Methods:

• Development of an ether-based electrolyte incorporating 1,3,5-trioxane.
• Investigation of temperature-dependent Li+ solvation structure and its effect on the electrode/electrolyte interface.
• Analysis of 1,3,5-trioxane-induced cationic ring-opening polymerization of tetrahydrofuran at elevated temperatures.
• Electrochemical testing of Li||LiNi0.8Co0.1Mn0.1O2 cells across a wide temperature range.
• Performance evaluation of a practical 1.5 Ah Li||Ni0.8Co0.1Mn0.1O2 pouch cell.

Main Results:

• The thermoresponsive electrolyte exhibits tunable Li+ solvation structures with temperature, promoting a polycrystalline interface.
• 1,3,5-trioxane facilitates anion dissociation and enhances charge-transfer kinetics.
• In-situ polymerization of tetrahydrofuran at 60°C forms oxidation-resistant polymers, improving high-temperature safety.
• Li||LiNi0.8Co0.1Mn0.1O2 cells demonstrate reliable operation from -60°C to 60°C.
• A 1.5 Ah pouch cell retained 74.7% capacity after 60 cycles at -40°C and achieved a specific energy of 317.1 Wh/kg.

Conclusions:

• The developed ether-based thermoresponsive electrolyte successfully addresses the limitations of conventional electrolytes.
• This electrolyte design enables high performance and safety in lithium metal batteries across extreme temperatures.
• The findings offer a promising pathway for developing advanced electrolytes for demanding energy storage applications.