Mn Ions Dissolution Mechanism for Lithium-Ion Battery with LiMn2O4 Cathode: in-Situ Ultraviolet-Visible Spectroscopy and ab initio Molecular Dynamics Simulations.
Mn Ions Dissolution Mechanism for Lithium-Ion Battery with LiMn2O4 Cathode: in-Situ Ultraviolet-Visible Spectroscopy and ab initio Molecular Dynamics Simulations.
复制标题
DOI：
10.1021/acs.jpclett.0c00936
复制
发表时间：
2020-03
期刊：
影响因子：
--
通讯作者：
Ge Zhou;Xiaorui Sun;Qing-hao Li;Xuelong Wang;Jie-Nan Zhang;Wanli Yang;Xiqian Yu;Ruijuan Xiao;Hong Li
中科院分区：
文献类型：
--
作者：
Ge Zhou;Xiaorui Sun;Qing-hao Li;Xuelong Wang;Jie-Nan Zhang;Wanli Yang;Xiqian Yu;Ruijuan Xiao;Hong Li
过渡金属(Tm)离子从正极材料溶解到液态电解液中，如从LiMn2O4(LMO)中溶解锰离子，不利于锂离子电池(LiBS)的循环性能。虽然这一问题已经引起了人们的广泛关注，但对锰的溶解行为还没有得到很好的揭示。本工作利用改进的原位紫外-可见吸收光谱(UV-Vis)技术，监测了不同荷电状态(SOC)下LMO液态电解液中溶解的Mn2+的浓度变化，确定了4.3V荷电状态下的最大溶解浓度和溶解速率，确定了电解液中的主要形态为Mn2+。通过从头算分子动力学(AIMD)模拟，揭示了锰的溶解过程与表面结构演变、溶剂分解和锂盐密切相关。这些结果将有助于理解TM在工作条件下的溶解机理以及稳定阴极的设计。
The dissolution of transition metal (TM) cations into liquid electrolyte from cathode material, such as Mn ions dissolution from LiMn2O4 (LMO), is detrimental to the cycling performance of Li-ion batteries (LIBs). Though much attention has been paid to this issue, the behavior of Mn dissolution has not been clearly revealed. In this work, by using a refined in-situ UV-visible absorption spectroscopy (UV-vis) technique, we monitored the concentration changes of dissolved Mn ions in liquid electrolyte from LMO at different state of charge (SOC), confirming the maximum dissolution concentration and rate at 4.3 V charged state and Mn2+ as the main specie in the electrolyte. Through ab initio molecular dynamics (AIMD) simulations, we revealed that Mn dissolution process is highly related to surface structure evolution, solvent decomposition and lithium salt. These results will contribute to understanding TM dissolution mechanisms in working conditions as well as the design of stable cathode.