Doi Kyosuke, Yamada Yuki, Okoshi Masaki, Ono Junichi, Chou Chien-Pin, Nakai Hiromi, Yamada Atsuo
Department of Chemical System Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30, Goryo-Ohara, Nishikyo-ku, Kyoto, 615-8245, Japan.
Angew Chem Int Ed Engl. 2019 Jun 11;58(24):8024-8028. doi: 10.1002/anie.201901573. Epub 2019 May 14.
Alkaline metals are an ideal negative electrode for rechargeable batteries. Forming a fluorine-rich interphase by a fluorinated electrolyte is recognized as key to utilizing lithium metal electrodes, and the same strategy is being applied to sodium metal electrodes. However, their reversible plating/stripping reactions have yet to be achieved. Herein, we report a contrary concept of fluorine-free electrolytes for sodium metal batteries. A sodium tetraphenylborate/monoglyme electrolyte enables reversible sodium plating/stripping at an average Coulombic efficiency of 99.85 % over 300 cycles. Importantly, the interphase is composed mainly of carbon, oxygen, and sodium elements with a negligible presence of fluorine, but it has both high stability and extremely low resistance. This work suggests a new direction for stabilizing sodium metal electrodes via fluorine-free interphases.
碱金属是可充电电池理想的负极。通过含氟电解质形成富含氟的界面层被认为是锂金属电极应用的关键，同样的策略也被应用于钠金属电极。然而，它们的可逆镀覆/剥离反应尚未实现。在此，我们报道了一种用于钠金属电池的无氟电解质的相反概念。一种四苯硼钠/单甘醇二甲醚电解质能够实现可逆的钠镀覆/剥离，在300次循环中平均库仑效率达到99.85%。重要的是，该界面层主要由碳、氧和钠元素组成，氟的存在可忽略不计，但它具有高稳定性和极低的电阻。这项工作为通过无氟界面层稳定钠金属电极提出了一个新方向。
