Relieving Rather Than Blocking: A Slide-Crosslinked Polymer Electrolyte for Dendrite-Free Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• High-performance lithium metal batteries require solid polymer electrolytes (SPEs) with high ionic conductivity and stable interfaces.
• Conventional crosslinked SPEs often exhibit rigidity, hindering their ability to manage lithium metal volume changes during battery cycling.

Purpose of the Study:

• To design and synthesize a novel slide-crosslinked SPE based on polyrotaxanes (PR-PVC) for improved lithium metal battery performance.
• To investigate the structure-property relationships of the PR-PVC electrolyte and optimize its formulation for enhanced electrochemical and mechanical properties.

Main Methods:

• In situ polymerization was employed to create the slide-crosslinked SPE (PR-PVC) with a "molecular pulley" architecture.
• Systematic optimization of polyrotaxane molecular structure and electrolyte composition was performed.
• Electrochemical performance was evaluated in Li//LFP cells.

Main Results:

• The optimized PR-PVC electrolyte demonstrated high ionic conductivity (2.61 mS cm^-1) and a high lithium-ion transference number (0.89).
• The electrolyte exhibited robust mechanical properties (3.4 GPa) and superior interfacial adaptability.
• Li//LFP cells utilizing the PR-PVC electrolyte showed stable cycling with 81.1% capacity retention after 500 cycles.

Conclusions:

• The slide-crosslinked SPE based on polyrotaxanes offers a promising strategy for developing next-generation high-energy-density lithium metal batteries.
• The unique architecture effectively dissipates stress, enhancing interfacial stability and accommodating volume fluctuations.
• This work provides key insights into designing advanced solid electrolytes for safer and more efficient batteries.