Surface iodine modification inducing robust CEI enables ultra-stable Li-Se batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 455; p. 140803
• Main Authors: Zhou, Mingran, Dong, Wenda, Xu, Ao, Yin, Zhiwen, Hu, Zhi-Yi, Wang, Xinling, Wu, Liang, Chen, Lihua, Li, Yu, Su, Bao-Lian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2023
• Subjects: Cathode electrolyte interface; Chemical reaction kinetics; Li-Se batteries; Surface iodine modification; Three-dimensional nano hollow carbon fiber network; Surface iodine modification; Chemical reaction kinetics; Cathode electrolyte interface; Three-dimensional nano hollow carbon fiber network; Li-Se batteries
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.140803

•Surface I modification of nano hollow carbon fiber (I-NHCF) enhances the Li+ and electrons transfer.•Surface I modification alters the chemical state of the NHCF surface.•Surface I modification promotes the formation of robust CEI.•Robust CEI prevents amorphous Se from infiltrating the surface of NHCF and converting into crystalline Se.•Se@I-NHCF cathode exhibits high reversible capacity and ultra-stable performance. Lithium-selenium batteries (LSeBs) have attracted increasing attention due to their excellent electronic conductivity and high theoretical specific capacity. However, there are still difficult problems such as low utilization rate and fast capacity decay in the actual application process. Herein, a surface iodine modified three-dimensional (3D) nano hollow carbon fiber (I-NHCF) network is designed and synthesized as Se host (Se@I-NHCF) for highly stable LSeBs. The surface iodine species induce the formation of robust cathode electrolyte interface (CEI), thus preventing the transformation of amorphous selenium to low-activity crystalline selenium and enabling stable electrochemical performance. Moreover, the surface iodine species promote rapid charge transfer, enhancing the chemical reaction kinetics and improving the utilization of the active Se species. As a result, the Se@I-NHCF cathode exhibits superior specific capacity of 581.8 mAh g−1 with a high stability (0.0054% capacity decay per cycle) after 500 cycles at 1C, and an excellent rate performance of 567.6 mAh g−1 at 2C. This work addresses the problem of rapid capacity decay by the formation of uniform and robust CEI to conserve highly reactive amorphous Se species, improve Se utilization, and achieve ultra-stable Li-Se batteries with high energy and long cycle life.