Revealing the Intrinsic Atomic Structure and Chemistry of Amorphous LiO2-Containing Products in Li–O2 Batteries Using Cryogenic Electron Microscopy,Journal of the American Chemical Society

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Revealing the Intrinsic Atomic Structure and Chemistry of Amorphous LiO2-Containing Products in Li–O2 Batteries Using Cryogenic Electron Microscopy
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2022-01-25 , DOI: 10.1021/jacs.1c10146
Peng Zhang _{1,

2} , Bing Han _{1,

3} , Xuming Yang ₁ , Yucheng Zou ₁ , Xinzhen Lu ₁ , Xiao Liu ₄ , Yuanmin Zhu _{1,

5} , Duojie Wu ₁ , Shaocheng Shen ₆ , Lei Li ₁ , Yong Zhao ₄ , Joseph S Francisco ₇ , Meng Gu ₁

Affiliation

Aprotic lithium–oxygen batteries (LOBs) are promising energy storage systems characterized by ultrahigh theoretical energy density. Extensive research has been devoted to this battery technology, yet the detailed operational mechanisms involved, particularly unambiguous identification of various discharge products and their specific distributions, are still unknown or are subjects of controversy. This is partly because of the intrinsic complexity of the battery chemistry but also because of the lack of atomic-level insight into the oxygen electrodes acquired via reliable techniques. In the current study, it is demonstrated that electron beam irradiation could induce crystallization of amorphous discharge products. Cryogenic conditions and a low beam dosage have to be used for reliable transmission electron microscopy (TEM) characterization. High-resolution cryo-TEM and electron energy loss spectroscopy (EELS) analysis of toroidal discharge particles unambiguously identified the discharge products as a dominating amorphous LiO₂ phase with only a small amount of nanocrystalline Li₂O₂ islands dispersed in it. In addition, uniform mixing of carbon-containing byproducts is identified in the discharge particles with cryo-EELS, which leads to a slightly higher charging potential. The discharge products can be reversibly cycled, with no visible residue after full recharge. We believe that the amorphous superoxide dominating discharge particles can lead researchers to reconsider the chemistry of LOBs and pay special attention to exclude beam-induced artifacts in traditional TEM characterizations.

中文翻译：

使用低温电子显微镜揭示 Li-O2 电池中非晶态含 LiO2 产品的本征原子结构和化学性质

质子锂-氧电池（LOBs）是具有超高理论能量密度的有前途的储能系统。对此电池技术进行了广泛的研究，但所涉及的详细运行机制，特别是对各种放电产物及其具体分布的明确识别，仍然未知或存在争议。这部分是因为电池化学的内在复杂性，但也因为缺乏对通过可靠技术获得的氧电极的原子级洞察力。在目前的研究中，证明了电子束辐照可以诱导非晶放电产物的结晶。必须使用低温条件和低光束剂量来进行可靠的透射电子显微镜 (TEM) 表征。₂相中仅分散有少量纳米晶Li ₂ O ₂岛。此外，在带有低温 EELS 的放电颗粒中发现含碳副产物的均匀混合，这导致了略高的充电电位。放电产物可以可逆循环，完全充电后没有可见的残留物。我们相信，以无定形超氧化物为主的放电粒子可以引导研究人员重新考虑 LOB 的化学性质，并特别注意排除传统 TEM 表征中的射束诱导伪影。

更新日期：2022-02-09

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