Xu Biyi, Li Xinyu, Yang Chao, Li Yutao, Grundish Nicholas S, Chien Po-Hsiu, Dong Kang, Manke Ingo, Fang Ruyi, Wu Nan, Xu Henghui, Dolocan Andrei, Goodenough John B
Materials Science and Engineering Program and Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States.
Helmholtz Centre Berlin for Materials and Energy, Hahn-Meitner-Platz 1, Berlin 14109, Germany.
J Am Chem Soc. 2021 May 5;143(17):6542-6550. doi: 10.1021/jacs.1c00752. Epub 2021 Apr 27.
The application of flexible, robust, and low-cost solid polymer electrolytes in next-generation all-solid-state lithium metal batteries has been hindered by the low room-temperature ionic conductivity of these electrolytes and the small critical current density of the batteries. Both issues stem from the low mobility of Li ions in the polymer and the fast lithium dendrite growth at the Li metal/electrolyte interface. Herein, Mg(ClO) is demonstrated to be an effective additive in the poly(ethylene oxide) (PEO)-based composite electrolyte to regulate Li ion transport and manipulate the Li metal/electrolyte interfacial performance. By combining experimental and computational studies, we show that Mg ions are immobile in a PEO host due to coordination with ether oxygen and anions of lithium salts, which enhances the mobility of Li ions; more importantly, an - formed Li-conducting LiMgCl/LiF interfacial layer homogenizes the Li flux during plating and increases the critical current density up to a record 2 mA cm. Each of these factors contributes to the assembly of competitive all-solid-state Li/Li, LiFePO/Li, and LiNiMnCoO/Li cells, demonstrating the importance of surface chemistry and interfacial engineering in the design of all-solid-state Li metal batteries for high-current-density applications.
柔性、坚固且低成本的固体聚合物电解质在下一代全固态锂金属电池中的应用受到了这些电解质室温离子电导率低以及电池临界电流密度小的阻碍。这两个问题都源于锂离子在聚合物中的迁移率低以及锂金属/电解质界面处锂枝晶的快速生长。在此，Mg(ClO)被证明是聚环氧乙烷（PEO）基复合电解质中一种有效的添加剂，可调节锂离子传输并控制锂金属/电解质界面性能。通过结合实验和计算研究，我们表明镁离子由于与醚氧和锂盐阴离子配位而在PEO主体中不移动，这增强了锂离子的迁移率；更重要的是，形成的Li导电LiMgCl/LiF界面层使电镀过程中的锂通量均匀化，并将临界电流密度提高到创纪录的2 mA cm。这些因素中的每一个都有助于组装具有竞争力的全固态Li/Li、LiFePO/Li和LiNiMnCoO/Li电池，证明了表面化学和界面工程在设计用于高电流密度应用的全固态锂金属电池中的重要性。
