Designing a Self-Extinguishing System in a Composite Electrolyte for Highly Safe Solid-State Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid polymer electrolytes (SPEs) face challenges balancing thermal safety and electrochemical performance in solid-state lithium batteries.
• Thermal runaway in SPEs remains a significant obstacle for their practical application.

Purpose of the Study:

• To design an intelligent self-extinguishing system to mitigate thermal runaway in SPEs.
• To enhance the safety and electrochemical performance of solid-state lithium batteries.

Main Methods:

• Development of microcapsules with a core-shell structure featuring a polymer shell and a flame retardant core.
• Incorporation of ion hopping points on the microcapsule shell to improve ionic conductivity.
• Testing of Li//Li symmetric cells and solid-state lithium metal batteries for cycling stability and capacity retention.

Main Results:

• The microcapsule system effectively prevents thermal runaway, demonstrating superior flame retardancy with a self-expansion time of 3 s g^-1.
• Achieved an ionic conductivity of 9.3 × 10^-4 S cm^-1.
• Demonstrated stable cycling for over 3400 h in Li//Li symmetric cells and 87.4% capacity retention after 500 cycles in solid-state Li metal batteries.

Conclusions:

• The core-shell microcapsule strategy offers a versatile approach to creating safe and high-performance solid-state Li-metal batteries.
• The intelligent self-extinguishing system addresses the critical safety concerns associated with SPEs.
• This work paves the way for the development of advanced energy storage solutions.