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Revisiting LiCoO2 Using a State-of-the-Art In Operando Technique.
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-07-22 , DOI: 10.1021/acs.inorgchem.0c01598
Kazuhiko Mukai 1 , Takeshi Uyama 1 , Takamasa Nonaka 1
Affiliation  

Lithium overstoichiometric cobalt oxide, Li(LiδCo1−δ)O2−δ, still occupies a privileged position as a positive electrode material for lithium-ion batteries. However, despite its widespread applications in commercial lithium-ion batteries, little is known about its reaction mechanisms and the effects of δ on cyclability at deep charge. We herein revisited this material through a recently developed in operando technique, i.e., rapid, alternating measurements of X-ray diffraction and X-ray absorption spectroscopy. The cyclability degraded when the charge cutoff voltage was >4.4 V versus Li+/Li, which corresponds to the Li composition exhibiting a minimum (maximum) lattice parameter along the ah (ch) axis. Differences in the structural parameters such as lattice parameters and bond distances clearly appeared between the charge and discharge reactions at a capacity below ∼220 mAh g–1. These changes occurred because deep charge and/or increasing the amount of δ induced a local distortion in the CoO6 octahedra. We found a critical Li extraction content that satisfied the need for both high capacity and cyclability for Li(LiδCo1−δ)O2−δ, which can be applied to other layered materials.

中文翻译:

使用Operando技术中的最新技术回顾LiCoO2。

锂过化学氧化钴,李(李δ1-δ)O 2-δ,仍占据有利地位,作为锂离子电池的正极材料。然而,尽管其在商业锂离子电池中得到了广泛的应用,但对其反应机理以及δ对深充电时循环性的影响知之甚少。我们在这里通过最近开发的一种操作技术,即X射线衍射和X射线吸收光谱的快速,交替测量来重新研究该材料。相对于Li + / Li,当电荷截止电压> 4.4 V时,可循环性降低,这与Li组成沿a方向具有最小(最大)晶格参数相对应hc h)轴。在小于约220 mAh g –1的容量下,充放电之间的结构参数如晶格参数和键距的差异明显出现。发生这些变化是因为深电荷和/或增加的δ量在CoO 6八面体中引起了局部变形。我们发现,满足了高容量和循环使用性能的李(李需要一个关键的李提取内容δ1-δ)O 2-δ,它可以适用于其他层状材料。
更新日期:2020-08-03
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