Mukai Kazuhiko
Toyota Central Research and Development Laboratories, Inc. , 41-1 Yokomichi , Nagakute , Aichi 480-1192 , Japan.
Inorg Chem. 2019 Aug 5;58(15):10377-10389. doi: 10.1021/acs.inorgchem.9b01565. Epub 2019 Jul 24.
Lithium zinc titanate spinel, LiZnTiO, has received significant attention as a negative electrode material for lithium-ion batteries (LIBs). However, its reaction mechanism has not been fully clarified yet, particularly for the large voltage hysteresis between discharge and charge curves. We hence closely examined (LiZn)[LiTi]O (LZTO) with 0 < ≤ 0.5 by measuring its open-circuit voltage (OCV) and recording synchrotron radiation X-ray diffraction (XRD) patterns. Here, LZTO is a solid solution of Li[LiTi]O ( = 0) and LiZnTiO ( = 0.5), both of which have a spinel-framework structure. For the = 0.5 sample, the OCV of the discharge reaction differed from that of the charge reaction, particularly at a capacity above 50 mAh·g. This difference was due to the migration of Zn ions from tetrahedral sites to octahedral sites, and the Zn ions moved back to tetrahedral sites during the charge reaction. Despite these drastic movements of Zn ions, the cubic lattice parameter of the spinel was maintained during the whole reaction, i.e., zero strain. Perfect zero strain, which has never been reported for any LIB materials, was achieved with the = 0.25 sample. The reaction mechanism with = 0.5 and the contributions of the amount of Zn ions are discussed in detail.
钛酸锂锌尖晶石LiZnTiO作为锂离子电池（LIBs）的负极材料受到了广泛关注。然而，其反应机理尚未完全阐明，特别是放电和充电曲线之间的大电压滞后现象。因此，我们通过测量开路电压（OCV）并记录同步辐射X射线衍射（XRD）图谱，对0 < ≤ 0.5的(LiZn)[LiTi]O（LZTO）进行了仔细研究。在此，LZTO是Li[LiTi]O（ = 0）和LiZnTiO（ = 0.5）的固溶体，二者均具有尖晶石骨架结构。对于 = 0.5的样品，放电反应的OCV与充电反应的不同，特别是在容量高于50 mAh·g时。这种差异是由于Zn离子从四面体位置迁移到八面体位置，并且在充电反应期间Zn离子又回到四面体位置。尽管Zn离子有这些剧烈移动，但在整个反应过程中尖晶石的立方晶格参数保持不变，即零应变。 = 0.25的样品实现了完美的零应变，这在任何LIB材料中都从未有过报道。详细讨论了 = 0.5时的反应机理以及Zn离子含量的贡献。
