“Water‐in‐Salt” Electrolyte Makes Aqueous Sodium‐Ion Battery Safe, Green, and Long‐Lasting,Advanced Energy Materials

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“Water‐in‐Salt” Electrolyte Makes Aqueous Sodium‐Ion Battery Safe, Green, and Long‐Lasting
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2017-07-21 , DOI: 10.1002/aenm.201701189
Liumin Suo ₁ , Oleg Borodin ₂ , Yuesheng Wang ₃ , Xiaohui Rong ₃ , Wei Sun ₁ , Xiiulin Fan ₁ , Shuyin Xu ₃ , Marshall A. Schroeder ₂ , Arthur V. Cresce ₂ , Fei Wang ₁ , Chongyin Yang ₁ , Yong-Sheng Hu ₃ , Kang Xu ₂ , Chunsheng Wang ₁

Affiliation

Narrow electrochemical stability window (1.23 V) of aqueous electrolytes is always considered the key obstacle preventing aqueous sodium‐ion chemistry of practical energy density and cycle life. The sodium‐ion water‐in‐salt electrolyte (NaWiSE) eliminates this barrier by offering a 2.5 V window through suppressing hydrogen evolution on anode with the formation of a Na⁺‐conducting solid‐electrolyte interphase (SEI) and reducing the overall electrochemical activity of water on cathode. A full aqueous Na‐ion battery constructed on Na_0.66[Mn_0.66Ti_0.34]O₂ as cathode and NaTi₂(PO₄)₃ as anode exhibits superior performance at both low and high rates, as exemplified by extraordinarily high Coulombic efficiency (>99.2%) at a low rate (0.2 C) for >350 cycles, and excellent cycling stability with negligible capacity losses (0.006% per cycle) at a high rate (1 C) for >1200 cycles. Molecular modeling reveals some key differences between Li‐ion and Na‐ion WiSE, and identifies a more pronounced ion aggregation with frequent contacts between the sodium cation and fluorine of anion in the latter as one main factor responsible for the formation of a dense SEI at lower salt concentration than its Li cousin.

中文翻译：

“盐包水”电解质使钠离子电池安全，绿色和持久耐用

水溶液电解质的狭窄电化学稳定性窗口（1.23 V）一直被认为是阻碍钠离子化学在实际能量密度和循环寿命方面的主要障碍。钠离子水包盐电解质（NaWiSE）通过提供一个2.5 V的窗口来消除此障碍，该窗口通过抑制阳极上的氢逸出以及形成Na ⁺导电的固体电解质中间相（SEI）并降低总体电化学活性而提供了一个2.5 V的窗口阴极上的水。基于Na _0.66 [Mn _0.66 Ti _0.34 ] O ₂作为阴极和NaTi ₂（PO ₄）₃构成的完整Na-离子水电池阳极在低速和高倍率下均表现出卓越的性能，例如在低速（0.2 C）下以高的库仑效率（> 99.2％）进行了超过350次循环，以及出色的循环稳定性，容量损失可忽略不计（每循环0.006％））以高速率（1 C）进行> 1200个循环。分子建模揭示了锂离子和钠离子WiSE之间的一些关键差异，并确定了钠离子与阴离子中的氟之间频繁接触而引起的更明显的离子聚集，后者是导致在室温下形成致密SEI的一个主要因素。盐浓度比其堂兄低。

更新日期：2017-07-21

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