High-energy-density lithium metal batteries (LMBs) are pivotal for green energy advancement and energy structure transformation, representing a key research focus for next-generation energy storage technologies. However, lithium metal anodes (LMA) face severe challenges during operation, particularly in conventional ester-based electrolytes with high oxidation windows. Unstable electrode interfaces lead to rapid capacity decay and uncontrolled lithium dendrite growth, critically limiting practical performance. Modifying the electrolyte to regulate the interfacial inorganic components is a fundamental approach to strengthen the fragile solid electrolyte interphase (SEI) and address these issues. Among various strategies, developing efficient electrolyte additives is regarded as the optimal approach due to cost-effectiveness and practicality.
In a recent publication in National Science Review , Professor Yuping Wu and Associate Prof. Tao Wang from Southeast University pioneer a novel thioether-based electrolyte additive: 1,3-dithiane. This additive reconstructs electrode interfaces through a triple synergistic mechanism:
1. Polarity inversion & SEI organic suppression: The highly acidic hydrogen at the 2-methylene position reacts with alkyl lithium to form the critical intermediate 2-lithio-1,3-dithiane. This species suppresses organic component formation in the SEI, decomposes to form a sulfur-rich interface on lithium surfaces, and converts unstable organics into sulfur-containing inorganics. Simultaneously, it significantly enhances carbonate solvents’ resistance to nucleophilic attack.
2. Kinetic & thermodynamic interfacial optimization: Leveraging preferential adsorption kinetics and thermodynamic redox properties, the additive forms a highly stable, high-dynamics interface on electrodes. This interface promotes PF 6 - anion participation in film formation, cooperatively building an inorganic-rich interphase with high ionic conductivity.
3. Ultrahigh sulfur utilization: With a sulfur content of 53.5% (nearly double conventional sulfur additives), it enables sustained interfacial regulation at low concentrations, opening new frontiers for sulfur-based additive development.
Surprisingly, Li||LiFePO 4 full cells using the modified electrolyte achieve 83.6% capacity retention after 3,300 cycles at 1C rate. Meanwhile, Lab-fabricated cells demonstrate 10 fold extended cycle life with 93.1% capacity retention after 150 cycles. This breakthrough delivers long-cycle LMB performance under quasi-commercial conditions, providing a low-cost universal strategy for constructing stable inorganic-rich interfaces. It not only advances practical LMBs but also expands new dimensions for thioether additive R&D.
This work was supported by: National Key R&D Program of China; National Natural Science Foundation of China; Jiangsu Provincial Key R&D Program; Southeast University High-Level Talent Startup Fund.
National Science Review