The lack of precise chemical information of solid-electrolyte interphase (SEI) is a huge obstacle for battery technology breakthroughs. Herein we identify the organic component of diglyme-based SEI by artificially synthesizing bulk crystals and reveal its intrinsic properties. The organic component of SEI shows a layered structure and it actually is formed by the co-solvation of Na+, triflate ion and diglyme (Na3T3D), rather than by the electrochemical reduction of diglyme. Low-current-beam transmission electron microscopy revealed that the organic component is crystalline and soluble in most solvents, which upend humanity’s understanding of its thin and amorphous features. Further, results disclosed that Na3T3D is the only organic SEI component and it is a super ionic conductor with rational migration pathways and facile energy barrier for Na+ migrating. Our work has overturned some existing misconceptions about the diglyme-based SEI and disclosed its essential characteristics.

中文翻译：

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钠离子电池中醚基固体电解质界面有机物的分子水平鉴定


固体电解质界面（SEI）精确化学信息的缺乏是电池技术突破的巨大障碍。在此，我们通过人工合成块状晶体来鉴定基于二甘醇二甲醚的SEI的有机成分并揭示其内在性质。 SEI的有机成分呈现层状结构，实际上是由Na+、三氟甲磺酸根离子和二甘醇二甲醚(Na3T3D)共溶剂化形成的，而不是由二甘醇二甲醚电化学还原形成的。低电流束透射电子显微镜显示，有机成分是结晶的，可溶于大多数溶剂，这颠覆了人类对其薄和无定形特征的理解。此外，结果表明Na3T3D是唯一的有机SEI组分，并且是一种超离子导体，具有合理的迁移路径和容易的Na+迁移能垒。我们的工作推翻了对基于二甘醇二甲醚的 SEI 的一些现有误解，并揭示了其基本特征。