Researchers at Zhejiang Sci-Tech University have developed a fiber-reinforced composite solid polymer electrolyte that overcomes the long-standing tradeoff between ionic conductivity and mechanical strength in polymer-based solid-state lithium metal batteries. Their breakthrough, published online on January 19, 2026, in the Chinese Journal of Polymer Science, represents a major step toward safer, longer-lasting, and manufacturable solid-state battery technologies.
Solid polymer electrolytes are attractive for lithium metal batteries because they are potentially compatible with high-capacity lithium anodes and can reduce safety risks associated with flammable liquid electrolytes. However, achieving high ionic conductivity without sacrificing mechanical robustness has remained a challenge, particularly in PEO-based polymers that become highly crystalline at room temperature.
The research team addressed this challenge by combining a porous PTFE fibrous membrane as a mechanical framework with a succinonitrile plastic-crystal additive in a PEO/PVDF-HFP/LiTFSI polymer matrix. This composite structure simultaneously promotes ion transport and reinforces mechanical stability.
Key performance highlights include:
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High ionic conductivity: 7.6×10⁻⁴ S·cm⁻¹ at 60 °C.
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Mechanical strength: 3.31 MPa tensile strength with 352% elongation, designed to resist lithium dendrite penetration.
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Exceptional cycling stability: Lithium symmetric cells operated for ~2,500 hours at 0.15 mA·cm⁻².
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Durable full-cell performance: Li//LiFePO₄ cells retained 91.6% capacity after 300 cycles at 0.5C with coulombic efficiency consistently above 99.9%.
“The PTFE fibrous membrane serves as a strong backbone, succinonitrile reduces polymer crystallinity to enhance Li⁺ transport, and PVDF-HFP supports salt dissolution and electrochemical stability,” said the research team. “By integrating these components, we’ve created a composite electrolyte that is both mechanically robust and highly conductive, overcoming a critical barrier in polymer-based solid-state batteries.”
This approach provides a practical materials strategy for scaling up safer, high-performance solid-state lithium metal batteries, which are crucial for next-generation energy storage, including electric vehicles and grid applications. The team envisions extending this design to other cathode chemistries and lower-temperature operations, accelerating the deployment of durable, high-energy, and safer polymer-based batteries.
