Slide-Crosslinked Polyrotaxane Topological Networks: Quasi-Solid Electrolyte for High-Voltage Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Conventional polymer electrolytes have limitations in oxidation resistance and mechanical strength for high-voltage lithium metal batteries.
• These limitations lead to capacity degradation and reduced battery lifespan, hindering the development of safer, high-energy-density batteries.

Purpose of the Study:

• To design and synthesize novel high-voltage-resistant sliding crosslinked quasi-solid electrolytes (PMBA-PPRx).
• To leverage the mechanical slide-ring structure of polyrotaxanes (PR) for improved electrolyte performance.
• To enhance the safety and lifespan of solid-state lithium metal batteries.

Main Methods:

• Synthesized PMBA-PPRx electrolytes via in situ thermal polymerization of vinyl functional polyrotaxanes (PPRs) and N,N'-methylenebisacrylamide (MBA).
• Investigated the synergistic enhancement of mechanical and electrochemical properties of the optimal PMBA-PPR5 electrolyte.
• Evaluated lithium dendrite suppression and interfacial compatibility.

Main Results:

• The optimal PMBA-PPR5 electrolyte exhibited enhanced mechanical robustness and high-voltage stability (up to ~5.5 V).
• The dynamic slide ring structure effectively dissipated energy from lithium dendrite growth, enabling stable Li deposition/stripping for over 2000 hours.
• Achieved improved lithium-ion transference number (0.69) and excellent cycling stability in Li|PMBA-PPR5|LFP and Li|PMBA-PPR5|NCM811 cells.

Conclusions:

• The slide-crosslinked polyrotaxane topological dynamic structure offers a new strategy for designing high-voltage lithium metal electrolytes.
• This approach significantly improves the performance and safety of solid-state lithium metal batteries.
• The developed electrolytes show great promise for next-generation high-energy-density battery applications.