动态结构 广泛脱的高压脊柱的演变 1+Ni0.5Mn1.5O4 x <1.5
Nicola M Jobst1, Neelima Paul2, Premysl Beran3,4
1Accumulators Materials Research (ECM), ZSW Centre for Solar Energy and Hydrogen Research Baden-Württemberg, DE-89081 Ulm, Germany.
Journal of the American Chemical Society
|February 17, 2023
概括
没有的高压螺旋电极材料为离子电池提供了更高的能量密度. 这项研究通过详细描述延长电压周期期间的结构变化来解释容量衰减和电压两极分化.
科学领域:
- 材料科学
- 电化学
- 固态化学
背景情况:
- 高压旋转材料,特别是LiNi0.5Mn1.5O4,是先进的离子电池的有希望的无阴极.
- 延长这些旋转器的操作电压窗口理论上增加了特定能量,但导致性能降低.
- 在扩展的电压范围内,导致容量衰减和电压两极分化的基础结构动力学尚不清楚.
研究的目的:
- 在延长的化/脱周期中阐明LiNi0.5Mn1.5O4的动态结构演变.
- 将观察到的结构变化与电化学性能相关联,特别是电压偏振和容量色.
- 为在扩展潜力窗口中观察到的独特电压配置提供全面的解释.
主要方法:
- 用静态度测量来研究热力学特性.
- 使用X射线衍射 (XRD) 和中子衍射在现场监测结构变化.
- 用最大方法分析化相的中子衍射数据.
主要成果:
- 在2.8V左右观察到一个双相反应 (立方到四角形),其中一个二次四角形相 (x > 2) 演变.
- 在解过程中,含量为x=1.5时形成的中间立方相.
- 中子衍射揭示了离子占据八面体 (8a) 和四面体 (4a) 在扭曲的四面体阶段 (I41amd) 的高度化状态 (2x<2.5).
结论:
- 结构演变,包括相位过渡和离子位点占用,为观察到的电压步骤 (2.10V和~3.80V) 和1.80V以下的倾斜电压配置提供了明确的解释.
- 了解这些结构动态对于减轻高压螺旋阴极材料的容量色和电压偏振至关重要.
- 这项研究有助于开发更稳定,更高能量密度的离子电池.
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