Thermodynamically Revealing the Essence of Order and Disorder Structures in Layered Cathode Materials  

作　　者：ZHENG Ze WENG Mou-Yi YANG Lu-Yi HU Zong-Xiang CHEN Zhe-Feng PAN Feng 

机构地区：[1]School of Advanced Materials, Shenzhen Graduate School,Peking University

出　　处：《Chinese Journal of Structural Chemistry》2019年第12期2020-2026,共7页结构化学（英文）

基　　金：Supported by National Key R&D Program of China(2016YFB0700600);Soft Science Research Project of Guangdong Province(No.2017B030301013)

摘　　要：Layered transition metal(TM) oxides are one of the most widely used cathode materials in lithium-ion batteries. The atomic configuration in TM layer of these materials is often known to be random when multiple TM elements co-exist in the layer(e.g. Ni, Co and Mn). By contrast, the configuration tends to be ordered if the elements are Li and Mn. Here, by using special quasi-random structures(SQS) algorithm, the essential reasons of the ordering in a promising Li-rich Mn-based cathode material Li2MnO3 are investigated. The difference of internal energy and entropy between ordered and disordered materials is calculated. As a result, based on the Gibbs free energy, it is found that Li2MnO3 should have an ordered structure in TM layer. In comparison, structures with Ni-Mn ratio of 2:1 are predicted to have a disordered TM layer, because the entropy terms have larger impact on the structural ordering than internal energy terms.Layered transition metal（TM） oxides are one of the most widely used cathode materials in lithium-ion batteries. The atomic configuration in TM layer of these materials is often known to be random when multiple TM elements co-exist in the layer（e.g. Ni, Co and Mn）. By contrast, the configuration tends to be ordered if the elements are Li and Mn. Here, by using special quasi-random structures（SQS） algorithm, the essential reasons of the ordering in a promising Li-rich Mn-based cathode material Li2MnO3 are investigated. The difference of internal energy and entropy between ordered and disordered materials is calculated. As a result, based on the Gibbs free energy, it is found that Li2MnO3 should have an ordered structure in TM layer. In comparison, structures with Ni-Mn ratio of 2:1 are predicted to have a disordered TM layer, because the entropy terms have larger impact on the structural ordering than internal energy terms.

关 键 词：ENTROPY special quasi-random structures(SQS) layered cathode materials Gibbs free energy 

分 类 号：TM912[电气工程—电力电子与电力传动] O614.111[理学—无机化学]