A Dual-Strategy of Iodine Doping and Electrolyte Additive Enabling Fast Reaction Kinetics and Robust Interface for Li-Se Batteries

en This link goes to a English section zh This link goes to a Chinese section Lithium-selenium (Li-Se) batteries have attracted considerable attention due to their high theoretical specific capacity and the intrinsically good electronic conductivity of selenium. Nevertheless, low active-material utilization, parasitic side reactions, and sluggish reaction kinetics hinder their practical application. Here, we propose a synergistic bulk-interfacial-engineering strategy that integrates an iodine-doping hollow carbon host (HNC@I) with a 5 vol% fluoroethylene carbonate (FEC) electrolyte additive for advanced Li-Se batteries. Structural and chemical analyses using TOF-SIMS (time-of-flight secondary ion mass spectrometry) and HRTEM (high-resolution transmission electron microscopy) confirm the presence of a compact, electrochemically stable, and mechanically robust LiF/LiI-rich cathode electrolyte interphase (CEI) layer, which prevents electrode cracking and enhances cycling stability. Iodine doping facilitates the Se ↔ Li 2 Se n ↔ Li 2 Se conversion kinetics, thus enhancing rate performance and mitigating electrode cracking. Benefiting from these synergistic effects, the HNC/Se@I | + 5 vol% FEC electrode delivers a reversible capacity of 580.6 mAh g −1 after 200 cycles at 0.2C and retains 503.3 mAh g −1 after 500 cycles at 1C. In addition, it achieves 677.6, 658.0, 641.0, 629.1, 564.6, and 449.3 mAh g −1 at 0.1C–5C, respectively, demonstrating excellent rate capability. This study provides new insights into interfacial optimization strategies for Li-Se batteries. 摘要 en This link goes to a English section zh This link goes to a Chinese section 锂-硒(Li-Se)电池因其高理论比容量以及硒本征优良的电子导电性而备受关注。然而,活性物质利用率低、副反应严重以及反应动力学迟缓等问题仍然阻碍其实际应用。在本工作中,我们提出了一种体相–界面协同工程策略,将碘掺杂空心碳载体(HNC@I)与体积分数为 5 vol% 的 FEC(氟代乙烯碳酸酯)电解液添加剂相结合,用于构筑高性能 Li-Se 电池。基于TOF-SIMS(飞行时间二次离子质谱)和HRTEM(高分辨透射电子显微镜)的结构与化学分析结果证实,电极表面形成了致密、电化学稳定且力学稳健的富LiF/LiI固体电解质界面(CEI)层,从而有效抑制电极开裂并提升循环稳定性。碘掺杂加速了Se↔Li 2 Se n ↔Li 2 Se的转化反应动力学,进而改善倍率性能并缓解电极开裂。得益于上述协同效应,HNC/Se@I | + 5 vol% FEC 电极在0.2C电流密度下循环200圈后仍能提供580.6 mAh g −1 的可逆比容量,并在1C下循环500圈后保持503.3 mAh g −1 的容量。此外,该电极在0.1C、0.2C、0.5C、1C、2C和5C倍率下分别实现了677.6、658.0、641.0、629.1、564.6和449.3 mAh g −1 的比容量,表现出优异的倍率性能,本研究为Li-Se电池的界面优化策略提供了新的见解与思路。