Li+ intercalation in isostructural Li2VO3 and Li2VO2F with O2- and mixed O2-/F- anions
Li+ intercalation in isostructural Li2VO3 and Li2VO2F with O2- and mixed O2-/F- anions
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DOI：
10.1039/c5cp02505b
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发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Hahn, Horst
中科院分区：
文献类型：
--
作者：
Chen, Ruiyong;Ren, Shuhua;Hahn, Horst
用于锂离子电池的混合阴离子材料因其可调节的电化学性能而引起人们的关注。在此，我们比较了两种同构（Fm (3) over barm）模型插层材料 Li2VO3 和 Li2VO2F 分别与 O2- 和混合 O2-/F- 阴离子。同步加速器 X 射线衍射和对分布函数数据证实了这些材料在长距离和原子尺度上的巨大结构相似性。然而，由于不同的阴离子环境以及随之而来的阳离子静电斥力的差异，它们表现出不同的电化学性质和动力学行为。与具有活跃V4+/5+氧化还原反应的Li2VO3相比，具有氧氟阴离子的材料Li2VO2F和V3+/5+氧化还原反应的部分活性有利于更高的理论容量（460 mA h g(-1) vs. 230 mA h g(-1)）、更高的电压（2.5 V vs. 2.2 V）、更低的极化（0.1 V vs. 0.3 V）和更快的Li+化学扩散（类似于 10(-9) cm(2) s(-1) 与类似于 10(-11) cm(2) s(-1)）。这项工作不仅为理解阴离子化学提供了见解，而且为新型混合阴离子电池材料的合理设计提供了建议。
Mixed-anion materials for Li-ion batteries have been attracting attention in view of their tunable electrochemical properties. Herein, we compare two isostructural (Fm (3) over barm) model intercalation materials Li2VO3 and Li2VO2F with O2- and mixed O2-/F- anions, respectively. Synchrotron X-ray diffraction and pair distribution function data confirm large structural similarity over long-range and at the atomic scale for these materials. However, they show distinct electrochemical properties and kinetic behaviour arising from the different anion environments and the consequent difference in cationic electrostatic repulsion. In comparison with Li2VO3 with an active V4+/5+ redox reaction, the material Li2VO2F with oxofluoro anions and the partial activity of V3+/5+ redox reaction favor higher theoretical capacity (460 mA h g(-1) vs. 230 mA h g(-1)), higher voltage (2.5 V vs. 2.2 V), lower polarization (0.1 V vs. 0.3 V) and faster Li+ chemical diffusion (similar to 10(-9) cm(2) s(-1) vs. similar to 10(-11) cm(2) s(-1)). This work not only provides insights into the understanding of anion chemistry, but also suggests the rational design of new mixed-anion battery materials.