Mahara Yuji, Nagasako Naoyuki, Oka Hideaki, Kondo Yasuhito, Kosaka Satoru, Nakano Hiroyuki, Nonaka Takamasa, Makimura Yoshinari
Toyota Central R&D Laboratories, Inc., Nagakute, Aichi 480-1192, Japan.
ACS Appl Mater Interfaces. 2022 Jun 1;14(21):24321-24331. doi: 10.1021/acsami.2c02868. Epub 2022 May 17.
In pursuit of high-capacity Mn-based oxides as positive electrode materials for lithium-ion batteries, the changes in the charge-discharge curve due to the spinel transition still stand in the way of the cycling stability. We found in this study that LiMnOF (LMOF05) positive electrodes with a loose-crystalline rock salt structure (LCRS), in which F is placed near Mn, show a stable and high capacity (300 mA h g, 952 W h kg) with little change in the charge-discharge curve. We demonstrated by F K-edge soft X-ray absorption spectroscopy and X-ray diffraction (XRD) that a part of F in the LCRS positive electrode forms F-Mn bonds. Operando XRD/X-ray absorption fine structure measurements revealed the lattice size and Mn surrounding environment during charge/discharge of F-containing LCRS positive electrodes (LMOF05), LCRS-LiMnO (LMO), and a spinel-like LiAlMnO positive electrode (SPINEL). Micro- and macroscopic structural changes indicate how the introduction of F suppresses the local spinel transition in Mn-based positive electrodes. These findings should be an effective tool for applying Co-free positive electrode materials for lithium-ion batteries.
在寻求高容量锰基氧化物作为锂离子电池正极材料的过程中，由于尖晶石转变导致的充放电曲线变化仍然阻碍着循环稳定性。我们在本研究中发现，具有松散结晶岩盐结构（LCRS）的LiMnOF（LMOF05）正极，其中F位于Mn附近，表现出稳定的高容量（300 mA h g，952 W h kg），充放电曲线变化很小。我们通过F K边软X射线吸收光谱和X射线衍射（XRD）证明，LCRS正极中的一部分F形成了F-Mn键。原位XRD/ X射线吸收精细结构测量揭示了含F的LCRS正极（LMOF05）、LCRS-LiMnO（LMO）和类尖晶石LiAlMnO正极（SPINEL）在充放电过程中的晶格尺寸和Mn周围环境。微观和宏观结构变化表明F的引入如何抑制锰基正极中的局部尖晶石转变。这些发现应该是应用无钴锂离子电池正极材料的有效工具。
