en.Wedoany.com Reported - A research team from South China Normal University has developed an in-situ polymerized solid-state electrolyte based on cross-linked poly(tetrahydrofuran) (poly(THF)), enabling lithium metal batteries to operate stably across a wide temperature range from -40°C to 55°C while maintaining high-voltage performance.
Solid-state batteries are considered an alternative to traditional lithium-ion batteries, but most solid polymer electrolytes suffer from low ionic conductivity, poor contact with electrodes, and limited high-voltage stability. Existing in-situ polymerized polyether electrolytes also tend to degrade when paired with high-voltage cathodes, affecting battery lifespan.
The team used an in-situ polymerization process to form the electrolyte directly inside the battery. The liquid precursor can achieve close contact with the electrodes before solidification and is compatible with existing lithium-ion battery production methods. By replacing the commonly used monomer 1,3-dioxolane with tetrahydrofuran, the team increased the electrolyte's oxidative stability to 4.9 volts. Ethylene glycol diglycidyl ether served as a cross-linking agent to construct a three-dimensional structure, providing additional pathways for lithium-ion movement and boosting room-temperature ionic conductivity to 3.3 mS/cm. Lithium difluoro(oxalato)borate (LiDFOB) functions both as a lithium salt and an initiator, forming a protective interfacial layer containing lithium fluoride and boron-oxygen-fluorine compounds on the electrode surface, thereby suppressing side reactions.
In tests paired with nickel-rich NCM811 and lithium cobalt oxide cathodes, the electrolyte exhibited minimal capacity loss after hundreds of cycles at a high cutoff voltage of 4.5 volts and covered an operating temperature range from -40°C to 55°C. The researchers noted that the material is suitable for electric vehicles, electric vertical takeoff and landing aircraft, and grid-scale energy storage systems.
The research team believes that this design strategy can be further extended to sodium-based and lithium-sulfur battery systems. The findings have been published in the journal eScience Energy.
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