Hosaka Tomooki, Noda Ayumi, Kubota Kei, Chiguchi Kento, Matsuda Yuki, Ida Kazuhiko, Yasuno Satoshi, Komaba Shinichi
Department of Applied Chemistry, Tokyo University of Science, Shinjuku-ku, Tokyo 162-8601, Japan.
Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Nishikyo-ku, Kyoto 615-8245, Japan.
ACS Appl Mater Interfaces. 2022 May 10;14(20):23507-17. doi: 10.1021/acsami.2c04289.
Superconcentrated aqueous electrolytes containing NaN(SOF) and KN(SOF) (for which sodium and potassium bis(fluorosulfonyl)amides (FSA), respectively, are abbreviated) have been developed for 2 V-class aqueous batteries. Based on the eutectic composition of the NaFSA-KFSA (56:44 mol/mol) binary system, the superconcentrated solutions of 35 mol kg NaKFSA/HO and 33 mol kg NaKFSA/HO are found to form at 25 °C. As both electrolytes demonstrate a wider potential window of ∼3.5 V compared to that of either saturated 20 mol kg NaFSA or 31 mol kg KFSA solution, we applied the 33 mol kg NaKFSA/HO to two different battery configurations, carbon-coated NaTi(PO)∥KMn[Fe(CN)] and carbon-coated NaV(PO)∥KMn[Fe(CN)]. The former cell shows highly reversible charge/discharge curves with a mean discharge voltage of 1.4 V. Although the latter cell exhibits capacity degradation, it demonstrates 2 V-class operations. Analysis data of the two cells confirmed that Na ions were mainly inserted into the negative electrodes passivated by a Na-rich solid electrolyte interphase, and both Na and K ions were inserted into the positive electrode. Based upon the observation, we propose new sodium-/potassium-ion batteries using the superconcentrated NaFSA-KFSA aqueous electrolytes.
含NaN(SOF)和KN(SOF)（分别为双（氟磺酰）亚胺钠（FSA）和双（氟磺酰）亚胺钾的缩写）的超浓缩水电解质已被开发用于2V级水系电池。基于NaFSA-KFSA（56:44摩尔/摩尔）二元体系的共晶组成，发现在25°C下形成35摩尔/千克NaKFSA/H₂O和33摩尔/千克NaKFSA/H₂O的超浓缩溶液。由于这两种电解质与饱和的20摩尔/千克NaFSA或31摩尔/千克KFSA溶液相比，都表现出约3.5V的更宽电位窗口，我们将33摩尔/千克NaKFSA/H₂O应用于两种不同的电池配置，碳包覆的NaTi₂(PO₄)₃∥K₃Mn[Fe(CN)₆]和碳包覆的Na₃V₂(PO₄)₃∥K₃Mn[Fe(CN)₆]。前一种电池显示出高度可逆的充放电曲线，平均放电电压为1.4V。尽管后一种电池表现出容量衰减，但它展示了2V级的运行。这两种电池的分析数据证实，Na离子主要插入由富Na固体电解质界面钝化的负极，并且Na和K离子都插入正极。基于该观察结果，我们提出了使用超浓缩NaFSA-KFSA水电解质的新型钠/钾离子电池。
