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Ultralight and fire-extinguishing current collectors for high-energy and high-safety lithium-ion batteries


Inactive components and safety hazards are two critical challenges in realizing high-energy lithium-ion batteries. Metal foil current collectors with high density are typically an integrated part of lithium-ion batteries yet deliver no capacity. Meanwhile, high-energy batteries can entail increased fire safety issues. Here we report a composite current collector design that simultaneously minimizes the ‘dead weight’ within the cell and improves fire safety. An ultralight polyimide-based current collector (9 μm thick, specific mass 1.54 mg cm−2) is prepared by sandwiching a polyimide embedded with triphenyl phosphate flame retardant between two superthin Cu layers (~500 nm). Compared to lithium-ion batteries assembled with the thinnest commercial metal foil current collectors (~6 µm), batteries equipped with our composite current collectors can realize a 16–26% improvement in specific energy and rapidly self-extinguish fires under extreme conditions such as short circuits and thermal runaway.

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Fig. 1: Conventional CCs and our design.
Fig. 2: Materials fabrication and structural characterization of PI-based CCs.
Fig. 3: Fire retardancy behaviour and Gr anode performance based on different CCs.
Fig. 4: Electrochemical characterization of the full cells fabricated using conventional CCs and PI-based CCs.
Fig. 5: Fire retardancy test on full pouch cells assembled using Al/Cu CC and PI-TPP-Al/PI-TPP-Cu CC pairs.

Data availability

All relevant data are included in the paper and its Supplementary Information. Source data are provided with this paper.


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This 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 eXtreme Fast Charge Cell Evaluation of Li-ion batteries (XCEL) program. We thank the Stanford Nano Shared Facilities (SNSF) and the Stanford Nanofabrication Facility (SNF) for SEM, FTIR, XPS, tensile strength characterizations and Lesker sputter fabrication.

Author information




Y. Ye and Y.C. conceived the concept. Y. Ye, Y.C. and Y.L. designed the experiments. Y. Ye and L.-Y.C. carried out the experimental works. Y. Ye and L.-Y.C. carried out the syntheses and performed material characterization, electrochemical measurements and flame retardancy tests. H.W., H.L., W.H., J.W. and K.L. assisted in the synthesis and characterization of materials. Y. Ye, Y.L., H.W., W.H., J.W., H.C., X.G. and S.C.K. helped with the data analysis. Y. Yang performed the SEM experiments. H.L. helped with the X-ray photoelectron spectroscopy measurement. A.Y. collected the FTIR spectra. X.X. helped with XRD experiments. Y. Ye and Y.C. wrote the paper. Y. Ye, W.H., G.Z, D.T.B. and W.Z. revised the paper. 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 Figs. 1–16 and Tables 1–14.

Supplementary Video 1

Tape peel testing of PI-TPP-based CC.

Supplementary Video 2

Flame retardancy test of Gr-coated Cu foil CC with electrolyte.

Supplementary Video 3

Flame retardancy test of Gr-coated PI-Cu CC with electrolyte.

Supplementary Video 4

Flame retardancy test of Gr-coated PI-TPP-Cu CC with electrolyte.

Supplementary Video 5

Flame retardancy test of LCO-Gr full cell based on commercial Al||Cu CC with electrolyte.

Supplementary Video 6

Flame retardancy test of LCO-Gr full cell based on PI-TPP-Al||PI-TPP-Cu CC with electrolyte.

Source data

Source Data Fig. 2

Statistical Source Data

Source Data Fig. 3

Statistical Source Data

Source Data Fig. 4

Statistical Source Data

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Ye, Y., Chou, LY., Liu, Y. et al. Ultralight and fire-extinguishing current collectors for high-energy and high-safety lithium-ion batteries. Nat Energy 5, 786–793 (2020).

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