Microcapsule-electrolyte enabling thermal shutdown toward safe lithium metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• High-energy-density lithium metal batteries face safety challenges due to thermal runaway.
• Developing safer battery electrolytes is crucial for advancing energy storage technologies.

Purpose of the Study:

• To develop an intelligent electrolyte system with a temperature-responsive thermal shutdown function for lithium metal batteries.
• To mitigate the risk of thermal runaway and improve battery safety and performance.

Main Methods:

• Incorporation of microencapsulated pentaerythritol tetraacrylate (PETEA) into the electrolyte.
• Synergistic interaction between PETEA and ethylene-terminated trimethylolpropane triacrylate (ETPTA) for in situ polymerization.
• Triggering of liquid-to-solid phase transition upon temperature elevation to block ion transport.

Main Results:

• Thermal runaway onset temperature increased from 140°C to 234°C in a 1 Ah pouch cell.
• Combustion tests showed significant reductions in peak temperature (67.7%) and total heat release (63.6%).
• Formation of a Li3N-rich solid electrolyte interphase (SEI) improved Li+ transport and suppressed dendrite growth, with LiFePO4//Li cells retaining 92.1% capacity after 300 cycles.

Conclusions:

• The intelligent electrolyte system effectively enhances thermal safety by inducing a rapid phase transition.
• The developed system offers a promising strategy for creating high-safety, high-energy-density lithium metal batteries.
• This approach contributes to the advancement of safer energy storage solutions.