Insight into the origin of lithium/nickel ions exchange in layered Li (NixMnyCoz)O-2 cathode materials
Insight into the origin of lithium/nickel ions exchange in layered Li (NixMnyCoz)O-2 cathode materials
复制标题
深入了解层状Li(NixMnyCoz)O-2正极材料中锂/镍离子交换的起源
DOI：
10.1016/j.nanoen.2018.04.020
复制
发表时间：
2018
期刊：
影响因子：
17.6
通讯作者：
Chen Hesheng
中科院分区：
文献类型：
--
作者：
Xiao Yinguo;Liu Tongchao;Liu Jiajie;He Lunhua;Chen Jie;Zhang Junrong;Luo Ping;Lu Huaile;Wang Rui;Zhu Weiming;Hu Zongxiang;Teng Gaofeng;Xin Chao;Zheng Jiaxin;Liang Tianjiao;Wang Fangwei;Chen Yuanbo;Huang Qingzhen;Pan Feng;Chen Hesheng
在锂离子电池层状LiNixMnyCozO 2正极材料中，过渡金属离子的自旋构成了一个二维的三角形网络，可以看作是一个简单的几何阻挫.通过中子粉末衍射实验和磁化强度测量，我们发现LiNixMnyCozO 2即使在3 K的低温下也不能建立长程磁有序.值得注意的是，这些化合物的阻挫参数估计大于30，表明TM离子的自旋之间存在强烈的阻挫磁相互作用。由于挫挫不可避免地会引起晶格不稳定性，Li/Ni交换的形成将有助于部分缓解挫磁晶格的简并性，在六方子晶格中形成稳定的反铁磁态，其中反铁磁离子位于六边形中心.此外，Li/Ni交换将引入180°超交换相互作用，通过引入新的交换路径进一步缓解磁阻挫。因此，Li/Ni交换比与TM摩尔分数的变化在LiNixMnyCozO 2与不同的组成可以很好地理解和预测的磁挫挫和超交换相互作用。这为研究层状Li（NixMnyCoz）O2正极材料的Li/Ni离子交换提供了一个独特的视角。
In layered LiNixMnyCozO2cathode material for lithium-ion batteries, the spins of transition metal (TM) ions construct a two-dimensional triangular networks, which can be considered as a simple case of geometrical frustration. By performing neutron powder diffraction experiments and magnetization measurements, we find that long-range magnetic order cannot be established in LiNixMnyCozO2even at low temperature of 3 K. Remarkably, the frustration parameters of these compounds are estimated to be larger than 30, indicating the existence of strongly frustrated magnetic interactions between spins of TM ions. As frustration will inevitably give rise to lattice instability, the formation of Li/Ni exchange in LiNixMnyCozO2will help to partially relieve the degeneracy of the frustrated magnetic lattice by forming a stable antiferromagnetic state in hexagonal sublattice with nonmagnetic ions located in centers of the hexagons. Moreover, Li/Ni exchange will introduce 180° superexchange interaction, which further relieves the magnetic frustration through bringing in new exchange paths. Thus, the variation of Li/Ni exchange ratio vs. TM mole fraction in LiNixMnyCozO2with different compositions can be well understood and predicted in terms of magnetic frustration and superexchange interactions. This provides a unique viewpoint to study the Li/Ni ions exchange in layered Li(NixMnyCoz)O2cathode materials.