Thermoresponsive Electrolytes for Safe Lithium-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium-metal batteries (LMBs) are crucial for high-energy storage but face significant thermal runaway risks.
• Improving the thermal safety of LMBs is essential for their widespread commercial adoption.
• Current safety strategies often fall short under extreme conditions.

Purpose of the Study:

• To design and evaluate a novel thermoresponsive electrolyte system for enhancing the thermal safety of LMBs.
• To investigate the mechanism by which the thermoresponsive electrolyte prevents thermal runaway.
• To assess the impact of the new electrolyte on key thermal safety parameters of LMBs.

Main Methods:

• Introduction of vinyl carbonate (VC) as a thermoresponsive solvent with azodiisobutyronitrile.
• Formation of a thermally stable poly(VC) layer within the solid electrolyte interphase (SEI).
• Analysis of thermal safety improvements using critical temperature for self-heating, internal short-circuit temperature, and ignition point measurements.

Main Results:

• The thermoresponsive electrolyte increased the critical temperature for thermal safety from 71.5 °C to 137.4 °C.
• Poly(VC) formation acted as a barrier, preventing electrode contact and immobilizing solvents.
• Internal short-circuit and ignition point temperatures were significantly raised to 176.5 °C and 203.6 °C, respectively.

Conclusions:

• The developed thermoresponsive electrolyte system substantially enhances the thermal safety of lithium-metal batteries.
• The strategy of using thermoresponsive solvents offers a promising approach for creating safer commercial electrolytes.
• This research provides valuable insights for designing next-generation thermally stable LMBs.