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Visualizing the growth process of sodium microstructures in sodium batteries by in-situ 23Na MRI and NMR spectroscopy.
Nature Nanotechnology ( IF 38.1 ) Pub Date : 2020-07-27 , DOI: 10.1038/s41565-020-0749-7
Yuxuan Xiang 1 , Guorui Zheng 1 , Ziteng Liang 1 , Yanting Jin 2 , Xiangsi Liu 1 , Shijian Chen 1 , Ke Zhou 1 , Jianping Zhu 1 , Min Lin 1 , Huajin He 1 , Jiajia Wan 1 , Shenshui Yu 1 , Guiming Zhong 3 , Riqiang Fu 4 , Yangxing Li 5 , Yong Yang 1
Affiliation  

The growth of sodium dendrites and the associated solid electrolyte interface (SEI) layer is a critical and fundamental issue influencing the safety and cycling lifespan of sodium batteries. In this work, we use in-situ 23Na magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) techniques, along with an innovative analytical approach, to provide space-resolved and quantitative insights into the formation and evolution of sodium metal microstructures (SMSs; that is, dendritic and mossy Na metal) during the deposition and stripping processes. Our results reveal that the growing SMSs give rise to a linear increase in the overpotential until a transition voltage of 0.15 V is reached, at which point violent electrochemical decomposition of the electrolyte is triggered, leading to the formation of mossy-type SMSs and rapid battery failure. In addition, we determined the existence of NaH in the SEI on sodium metal with ex-situ NMR results. The poor electronic conductivity of NaH is beneficial for the growth of a stable SEI on sodium metal.



中文翻译:

通过23Na MRI和NMR光谱可视化钠电池中钠微结构的生长过程。

钠树枝状晶体和相关的固体电解质界面(SEI)层的生长是影响钠电池安全性和循环寿命的关键和根本性问题。在这项工作中,我们使用原位23Na磁共振成像(MRI)和核磁共振(NMR)技术,以及创新的分析方法,可为钠金属微结构(SMS)的形成和演化提供空间分辨和定量的见解;即树突状和生苔的Na金属)在沉积和剥离过程中。我们的结果表明,不断增长的SMS会导致过电势线性增加,直到达到0.15 V的过渡电压为止,此时触发电解质的剧烈电化学分解,从而导致生成苔藓型SMS和快速电池失败。此外,我们用异位NMR结果确定了钠金属中SEI中NaH的存在。NaH的不良电导率有利于在钠金属上生长稳定的SEI。

更新日期:2020-07-27
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