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Vol. 18 (2026)

Dual Interlocked Mediators Enable Single-Ion-Conducting Quasi-Solid-State Electrolytes for Ultrafast-Charging Long-Life Sodium Metal Batteries

https://doi.org/10.1007/s40820-026-02236-2
Yuan Zhang
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Long Pan
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Cheong Wa Leong
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Xing‑Guo Qi
HiNa Battery Technology Co., Ltd., Beijing 213300, People’s Republic of China
Xiaozhong Huang
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Xinyi Cai
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Mufan Cao
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Min Gao
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Haoyu Zhang
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
Dawei Sha
Institute of Technology for Carbon Neutralization, College of Electrical, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, People’s Republic of China
Yang Zhou
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China
ZhengMing Sun
State Key Laboratory of Engineering Materials for Major Infrastructure, School of Materials Science and Engineering, Southeast University, Nanjing 211189, People’s Republic of China

Corresponding Author: ZhengMing Sun

zmsun@seu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 381

Abstract

Quasi-solid-state electrolytes (QSEs) are critical for ultrafast-charging yet high-safety sodium metal batteries (SMBs), yet their implementation is hindered by sluggish Na+ transport in bulk and at interfaces. Here, we propose dual interlocked mediator engineering that transcends conventional independent approaches by coupling cationic Sn2+ salt with anionic difluoro(oxalato)borate (DFOB⁻) salts to simultaneously regulating bulk ion transport and bilateral interface chemistry. During QSE preparation, Sn2+ initiates in situ cationic polymerization, while DFOB⁻ acts as a retarding agent to suppress runaway polymerization. The first interlocking effect in the Sn-FB QSE bulk builds a uniform network, enabling near-unity Na+ transference number (0.94) and robust puncture strength (8.5 kPa). During cell operation, Sn2+ is reduced to form a hybrid NaSn alloy-based solid-electrolyte interphase, while DFOB⁻ oxidizes to generate a robust yet thin cathode–electrolyte interphase, respectively. This second interlocking effect creates adaptable bilateral interphases that facilitate Na+ diffusion and mitigate interfacial degradation. As a result, the symmetric cells exhibit 6000 h stability, and full cells retain 80.1 mAh g–1 at an ultrafast-charging rate of 15C and retain 90% capacity at 3C over 2000 cycles. Furthermore, high-mass-loading full cells and pressure-free pouch cells are demonstrated, underscoring the potential of dual interlocked mediator engineering for practical SMBs.


Highlights:
1 Single-ion conduction. Sn-FB quasi-solid-state electrolytes (QSEs) achieves near-unity Na+ transference number (0.94) and high conductivity (1.3 mS cm–1) via synergistic Sn2+ initiated polymerization and difluoro(oxalato)borate (DFOB⁻) retardation.
2 Highly adaptable bilateral interphases. Sn2+ was reduced to form a hybrid NaSn alloy/inorganic-rich solid-electrolyte interphase to homogenize electric fields, while DFOB– was oxidized to form robust, yet thin cathode–electrolyte interphase for rapid interfacial kinetics.
3 Superior electrochemical performances. Sn-FB QSE delivers 6000 h stability without dendrite and retains 90% capacity after 2000 cycles at 3C.

Keywords

Interlocked mediator engineering Single-ion-conduction Quasi-solid-state electrolyte Electrode–electrolyte interphase Sodium metal batteries
Zhang, Yuan, Long Pan, Cheong Wa Leong, Xing‑Guo Qi, Xiaozhong Huang, Xinyi Cai, Mufan Cao, Min Gao, Haoyu Zhang, Dawei Sha, Yang Zhou, and ZhengMing Sun. 2026. “Dual Interlocked Mediators Enable Single-Ion-Conducting Quasi-Solid-State Electrolytes for Ultrafast-Charging Long-Life Sodium Metal Batteries”. Nano-Micro Letters 18 (May):381. https://doi.org/10.1007/s40820-026-02236-2.
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