Polyrotaxane-engineered dynamically adaptive slide-crosslinked polymer electrolyte enabling high-performance...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state lithium metal batteries (LMBs) face challenges with lithium dendrite growth and anode volume changes, limiting safety and cycle life.
• Conventional polymer electrolytes exhibit a trade-off between mechanical properties and ionic conductivity, hindering high-performance applications.
• Developing advanced electrolytes is crucial for overcoming current limitations in LMB technology.

Purpose of the Study:

• To design and synthesize a dynamically adaptive slide-crosslinked polymer electrolyte (PPRx-PVC) for high-performance LMBs.
• To investigate the relationship between polyrotaxane molecular weight and electrolyte performance.
• To address the critical issues of mechanical robustness, interfacial stability, and ion transport in LMBs.

Main Methods:

• In-situ copolymerization of vinyl-functionalized pseudopolyrotaxane (PPRx=) and vinylene carbonate (VC) to create the PPRx-PVC electrolyte.
• Utilizing the molecular pulley mechanism of polyrotaxane for enhanced mechanical properties and energy dissipation.
• Systematic optimization of PPRx= molecular weight (Mn ≈ 20,000 g mol⁻¹) and electrochemical testing.

Main Results:

• The optimized PPR20000-PVC electrolyte achieved a high Young's modulus (>2 GPa), Li⁺ transference number of 0.78, and electrochemical stability window of 4.85 V.
• Demonstrated suppressed lithium dendrite growth over 1300 h of plating/stripping and enhanced interfacial durability.
• Achieved 93.2% capacity retention over 200 cycles in Li||LiFePO₄ (LFP) batteries at 0.5C.

Conclusions:

• The dynamically adaptive slide-crosslinked polymer electrolyte offers a promising solution for high-performance and safe lithium metal batteries.
• The molecular pulley mechanism provides a synergistic enhancement of mechanical and electrochemical properties.
• This work presents a new design strategy for polymer electrolytes that concurrently addresses mechanical durability, interfacial compatibility, and ion transport.