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Ultrathin, flexible, solid polymer composite electrolyte enabled with aligned nanoporous host for lithium batteries



The urgent need for safer batteries is leading research to all-solid-state lithium-based cells. To achieve energy density comparable to liquid electrolyte-based cells, ultrathin and lightweight solid electrolytes with high ionic conductivity are desired. However, solid electrolytes with comparable thicknesses to commercial polymer electrolyte separators (~10 μm) used in liquid electrolytes remain challenging to make because of the increased risk of short-circuiting the battery. Here, we report on a polymer–polymer solid-state electrolyte design, demonstrated with an 8.6-μm-thick nanoporous polyimide (PI) film filled with polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) that can be used as a safe solid polymer electrolyte. The PI film is nonflammable and mechanically strong, preventing batteries from short-circuiting even after more than 1,000 h of cycling, and the vertical channels enhance the ionic conductivity (2.3 × 10−4 S cm−1 at 30 °C) of the infused polymer electrolyte. All-solid-state lithium-ion batteries fabricated with PI/PEO/LiTFSI solid electrolyte show good cycling performance (200 cycles at C/2 rate) at 60 °C and withstand abuse tests such as bending, cutting and nail penetration.

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Fig. 1: Design of polymer–polymer composite SSE.
Fig. 2: Characterization and understanding of PEO/LiTFSI in aligned channels.
Fig. 3: Mechanical and fire-retarding properties of PI/PEO/LiTFSI.
Fig. 4: Full-cell performance with PI/PEO/LiTFSI-based batteries.
Fig. 5: Abuse tests of PI/PEO/LiTFSI.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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The work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy under the Battery Materials Research (BMR) programme and Battery 500 Consortium programme. Z.L. and L.-Q.C. also acknowledge the support from the Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), under the Award (DE-EE0007803).

Author information




J. Wan, J.X. and Y.C. designed the research. J. Wan and J.X. conducted the fabrication and electrochemical characterization of the hybrid SPE. J. Wan, J.X., K.L., F.S. and H.C. did sample characterizations. W.C., J.C., J. Wang and X.Z. helped with sample fabrication and processing. X.K. and J.Q. performed the molecular dynamics simulations and data analysis. Z.L. and L.-Q.C. performed the phase field simulations and data analysis. J. Wan, J.X., F.S., A.P. and Y.C. wrote the manuscript. All authors contributed to the discussion of the manuscript.

Corresponding author

Correspondence to Yi Cui.

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The authors declare no competing interests.

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Supplementary information

Supplementary information

Supplementary Methods, Supplementary Figs. 1–24 and Supplementary Table 1

Supplementary Video 1

Flame test of PP/PE/PP separator

Supplementary Video 2

Flame test of PEO/LiTFSI SPE

Supplementary Video 3

Flame test of PI film

Supplementary Video 4

Nail penetration test of LFP/PI/PEO/LiTFSI/Li pouch cell

Supplementary Video 5

Phase evolution of Li deposition with PI/PEO/LiTFSI/PEO/Al2O3

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Wan, J., Xie, J., Kong, X. et al. Ultrathin, flexible, solid polymer composite electrolyte enabled with aligned nanoporous host for lithium batteries. Nat. Nanotechnol. 14, 705–711 (2019).

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