Directionally Aligned "Mechanical Balance" Design Enables Near-Frictionless Li⁺ Transport in Polymer Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Polymer electrolytes offer processability and good interfacial compatibility for lithium metal batteries.
• However, low ionic conductivity due to Li+-polymer interactions and tortuous pathways limits their performance.

Purpose of the Study:

• To develop a novel strategy for enhancing ionic conductivity in polymer electrolytes.
• To overcome limitations of Li+-polymer interactions and ion transport pathways.

Main Methods:

• Implementation of a mechanical balance (MB) zone strategy using anchored anion clusters to counteract Li+-polymer interactions.
• Directional alignment of MB zones via a fluorinated graphene/zeolitic imidazolate framework-8 (FG/ZIF-8) scaffold with in situ-polymerized 1,3-dioxolane.
• Fabrication and testing of Li|LiFePO4 and Li|LiNi0.5Co0.2Mn0.3O2 cells.

Main Results:

• Achieved ionic conductivity of 1.2 mS cm-1 at 25 °C and a Li+ transference number of 0.71.
• Demonstrated excellent rate capability (97.7 mAh g-1 at 8C) and ultralong cyclability (81% retention after 3500 cycles at 4C).
• Showcased compatibility with high-voltage cathodes and superior performance in practical pouch cells.

Conclusions:

• The MB paradigm offers a universal approach for designing advanced polymer electrolytes.
• This strategy enables superior ionic conduction for high-performance quasi-solid-state batteries.
• The developed electrolytes show great promise for next-generation lithium metal batteries.