Ultraconcentrated Sodium Bis(fluorosulfonyl)imide-Based Electrolytes for High-Performance Sodium Metal Batteries

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• 作者：Jaegi Lee ; Yongwon Lee ; Jeongmin Lee ; Sang-Min Lee ; Jeong-Hee Choi ; Hyungsub Kim ; Mi-Sook Kwon ; Kisuk KangKyu Tae Lee ; Nam-Soon Choi
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：February 1, 2017
• 年：2017
• 卷：9
• 期：4
• 页码：3723-3732
• 全文大小：651K
• ISSN：1944-8252

文摘

We present an ultraconcentrated electrolyte composed of 5 M sodium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane for Na metal anodes coupled with high-voltage cathodes. Using this electrolyte, a very high Coulombic efficiency of 99.3% at the 120th cycle for Na plating/stripping is obtained in Na/stainless steel (SS) cells with highly reduced corrosivity toward Na metal and high oxidation durability (over 4.9 V versus Na/Na⁺) without corrosion of the aluminum cathode current collector. Importantly, the use of this ultraconcentrated electrolyte results in substantially improved rate capability in Na/SS cells and excellent cycling performance in Na/Na symmetric cells without the increase of polarization. Moreover, this ultraconcentrated electrolyte exhibits good compatibility with high-voltage Na₄Fe₃(PO₄)₂(P₂O₇) and Na_0.7(Fe_0.5Mn_0.5)O₂ cathodes charged to high voltages (>4.2 V versus Na/Na⁺), resulting in outstanding cycling stability (high reversible capacity of 109 mAh g^–1 over 300 cycles for the Na/Na₄Fe₃(PO₄)₂(P₂O₇) cell) compared with the conventional dilute electrolyte, 1 M NaPF₆ in ethylene carbonate/propylene carbonate (5/5, v/v).