石墨
材料科学
电解质
化学工程
电极
电化学
阳极
傅里叶变换红外光谱
X射线光电子能谱
复合材料
化学
工程类
物理化学
作者
Zhaohua Wang,Haoyi Yang,Yiran Liu,Ying Bai,Guanghai Chen,Ying Li,Xinran Wang,Huajie Xu,Chuan Wu,Jun Lü
出处
期刊:Small
[Wiley]
日期:2020-11-27
卷期号:16 (51)
被引量:91
标识
DOI:10.1002/smll.202003268
摘要
Abstract Considerable efforts have been exerted to understand the formation and properties of the solid electrolyte interphase (SEI) in sodium ion batteries. However, the puzzling existence and role of SEI behind the huge volume changes of the graphite electrodes need to be answered. Herein, the reason of how ether‐derived SEI maintains excellent reversibility despite the huge volume changes during cycling is unraveled. Theoretical simulations and Fourier‐transform infrared spectroscopy demonstrate the formation mechanism of an SEI between the graphite anode and electrolyte. Furthermore, the high mechanical tolerance of the ether‐derived SEI is confirmed in atomic force microscopy. A depth profile of X‐ray photoelectron spectroscopy points to a multilayer structure of the ether‐derived SEI. The outer layer comprises organics (sodium alkoxide), while the inorganics (Na 2 CO 3 , NaF) in interior region are mixed with some organics. Notably, the presence of organics ensures the adaptability of the SEI to the volume expansion of graphite during cycling, and the concentrated distribution of inorganics improves the Young's modulus (resistance to deformation). Therefore, the graphite anode exhibits high cycle stability (96.6% capacity retention ratio at 1 A g –1 over 860 cycles) and efficiency (≈99.5%).
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