Sn<sup>2+</sup> bridging enhanced oxidation stability of polyether solid-state electrolyte for stable sodium metal batteries

LI Xiaoyu; ZHANG Hongkun; HOU Minjie; ZHOU Huangkai; LIANG Feng

doi:10.7513/j.issn.1004-7638.2026.04.008

Volume 47 Issue 4

Aug. 2026

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LI Xiaoyu, ZHANG Hongkun, HOU Minjie, ZHOU Huangkai, LIANG Feng. Sn2+ bridging enhanced oxidation stability of polyether solid-state electrolyte for stable sodium metal batteries[J]. IRON STEEL VANADIUM TITANIUM, 2026, 47(4): 66-76. doi: 10.7513/j.issn.1004-7638.2026.04.008

Citation:

LI Xiaoyu, ZHANG Hongkun, HOU Minjie, ZHOU Huangkai, LIANG Feng. Sn²⁺ bridging enhanced oxidation stability of polyether solid-state electrolyte for stable sodium metal batteries[J]. IRON STEEL VANADIUM TITANIUM, 2026, 47(4): 66-76. doi: 10.7513/j.issn.1004-7638.2026.04.008

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Sn²⁺ bridging enhanced oxidation stability of polyether solid-state electrolyte for stable sodium metal batteries

doi: 10.7513/j.issn.1004-7638.2026.04.008

LI Xiaoyu^{1, 2, 3
,},
ZHANG Hongkun^{1, 2, 3},
HOU Minjie^{1, 2, 3},
ZHOU Huangkai^{1, 2, 3},
LIANG Feng^{1, 2, 3
,
,}

1.
National Engineering Research Center for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, Yunan, China
2.
Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, Yunan, China
3.
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, Yunan, China

More Information

Received Date: 2026-05-28
Accepted Date: 2026-08-05
Rev Recd Date: 2026-07-10
Publish Date: 2026-08-31

Abstract

Abstract

Polyether-based solid-state electrolytes suffer from an intrinsically narrow electrochemical oxidation window that limits their compatibility with high-voltage cathode materials, while sodium metal anodes face the challenges of uncontrollable dendrite growth and continuous rupture-reconstruction of the solid electrolyte interphase (SEI) during cycling. These two issues jointly hinder the practical application of solid-state sodium metal batteries. In this work, an "ion-bridging" design strategy is proposed, in which tin(II) trifluoromethanesulfonate (Sn(OTf)₂) serves as a Lewis acid initiator to trigger the in situ ring-opening polymerization of 1,3-dioxolane (DOL) combined with cellulose triacetate (CTA), constructing a SnPDOL-CTA dual-network solid-state electrolyte. Using a metal-ion-free tris(pentafluorophenyl)borane (B(C₆F₅)₃)-initiated system as the control, we systematically analyzed the polymer structure, thermal properties, ionic transport, and electrochemical stability of the electrolyte, together with the deposition morphology and SEI chemical composition at the sodium metal anode. This comparison reveals the synergistic modulation mechanism of the Sn²⁺ ion-bridging structure in electrolyte performance and anode interfacial stability. Sn²⁺ coordinates simultaneously with the ether oxygen functional groups in both the PDOL chains and the CTA backbone, forming a dual-network crosslinked structure that lowers the highest occupied molecular orbital (HOMO) energy level of the system from −7.96 eV to −13.01 eV, expanding the electrochemical stability window beyond 4.5 V. The SnPDOL-CTA electrolyte exhibits a room-temperature ionic conductivity of 3.35×10⁻⁴ S·cm⁻¹ and a Na+ transference number of 0.64. Na||Na symmetric cells achieve stable cycling for over 1100 h with a critical current density of 1.1 mA·cm⁻². Sn²⁺ is in-situ reduced on the sodium metal anode surface, forming an organic-inorganic composite SEI layer rich in NaF and Na-Sn alloys, which effectively guides dense sodium deposition and suppresses dendrite growth. The half cells assembled with Na₃V₂(PO₄)₃ and Na₃V₂(PO₄)₂F₃ cathodes both deliver good cycling stability and rate capability.
- sodium metal battery,
- solid-state electrolyte,
- in situ polymerization,
- poly(1,3-dioxolane) (PDOL)

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References(31)

References

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