A critical challenge for next-generation lithium-based batteries lies in development of electrolytes that enable thermal safety along with the use of high-energy-density electrodes. We describe molecular ionic composite electrolytes based on an aligned liquid crystalline polymer combined with ionic liquids and concentrated Li salt. This high strength (200 MPa) and non-flammable solid electrolyte possesses outstanding Li+ conductivity (1 mS cm−1 at 25 °C) and electrochemical stability (5.6 V versus Li|Li+) while suppressing dendrite growth and exhibiting low interfacial resistance (32 Ω cm2) and overpotentials (≤120 mV at 1 mA cm−2) during Li symmetric cell cycling. A heterogeneous salt doping process modifies a locally ordered polymer–ion assembly to incorporate an inter-grain network filled with defective LiFSI and LiBF4 nanocrystals, strongly enhancing Li+ conduction. This modular material fabrication platform shows promise for safe and high-energy-density energy storage and conversion applications, incorporating the fast transport of ceramic-like conductors with the superior flexibility of polymer electrolytes.
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All data generated and analysed in this study are included in this published article and its Supplementary Information file and are also available from the corresponding author on reasonable request. Source data are provided with this paper.
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This work was supported primarily by the US National Science Foundation under awards DMR 1507764 and 1810194 and in part by the US Department of Energy under award EE0008860. We also gratefully thank C. Slebodnick at the Virginia Tech Crystallography Lab for assistance with X-ray diffraction analysis.
The authors declare no competing interests.
Peer review information: Nature Materials thanks Fannie Alloin and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Wang, Y., Zanelotti, C.J., Wang, X. et al. Solid-state rigid-rod polymer composite electrolytes with nanocrystalline lithium ion pathways. Nat. Mater. (2021). https://doi.org/10.1038/s41563-021-00995-4