Rechargeable batteries paired with sodium metal anodes are considered to be one of the most promising high-energy and low-cost energy-storage systems. However, the use of highly reactive sodium metal and the formation of sodium dendrites during battery operation have caused safety concerns, especially when highly flammable liquid electrolytes are used. Here we design and develop solvent-free solid polymer electrolytes (SPEs) based on a perfluoropolyether-terminated polyethylene oxide (PEO)-based block copolymer for safe and stable all-solid-state sodium metal batteries. Compared with traditional PEO SPEs, our results suggest that block copolymer design allows for the formation of self-assembled nanostructures leading to high storage modulus at elevated temperatures with the PEO domains providing transport channels even at high salt concentration (ethylene oxide/sodium = 8/2). Moreover, it is demonstrated that the incorporation of perfluoropolyether segments enhances the Na+ transference number of the electrolyte to 0.46 at 80 °C and enables a stable solid electrolyte interface. The new SPE exhibits highly stable symmetric cell-cycling performance at high current density (0.5 mA cm−2 and 1.0 mAh cm−2, up to 1,000 h). Finally, the assembled all-solid-state sodium metal batteries demonstrate outstanding capacity retention, long-term charge/discharge stability (Coulombic efficiency, 99.91%; >900 cycles with Na3V2(PO4)3 cathode) and good capability with high loading NaFePO4 cathode (>1 mAh cm−2).
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All the data supporting the findings of this work are in the paper and Supplementary Information. Additional data are available from the corresponding authors upon reasonable request. Source data are provided with this paper.
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The authors acknowledge the support of the Australia–India Strategic Research Fund (AISRF 48515) and the Australian Research Council for funding through the Industry Transformation Training Centre Scheme (IC180100049). The research reported here was partially supported by the National Science Foundation (NSF) through the Materials Research Science and Engineering Center at UC Santa Barbara, DMR-1720256 (IRG-2). A.K.W. and C.Z. acknowledge support from the Australian Research Council (CE140100036) and National Health and Medical Research Council for an Early Career Fellowship (APP1157440 to C.Z.). The authors acknowledge the use of the facilities and the assistance of Y. Hora at the Monash X-ray platform. The Australian National Fabrication Facility, Queensland Node, is also acknowledged for access to some items of equipment.
The authors declare no competing interests.
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Wang, X., Zhang, C., Sawczyk, M. et al. Ultra-stable all-solid-state sodium metal batteries enabled by perfluoropolyether-based electrolytes. Nat. Mater. 21, 1057–1065 (2022). https://doi.org/10.1038/s41563-022-01296-0