基于第一性原理高价元素Mo稳定层状富锂锰基材料的氧框架机制  

Oxygen Framework Mechanism of Layered Lithium-rich Manganese-based Materials Stabilized by High-valent Element Mo Based on First-principles Calculations

作　　者：张硕 赵刘洋 黄昊[1] 吴爱民[1] 李爱魁 ZHANG Shuo;ZHAO Liuyang;HUANG Hao;WU Aimin;LI Aikui(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China;School of Electrical Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学材料科学与工程学院,大连116024 [2]大连理工大学电气工程学院,大连116024

出　　处：《高等学校化学学报》2024年第5期110-119,共10页Chemical Journal of Chinese Universities

基　　金：陕煤-秦岭基础科学研究五年行动计划项目(批准号:SMYJY202400012C)资助。

摘　　要：采用基于密度泛函理论的第一性原理计算探究了高价元素Mo取代Mn稳定层状富锂锰基材料氧离子框架机制.Mo掺杂将体积变化率从‒2.95%降至‒0.53%,改善了锂化前后的晶格畸变.空位形成能及巴德电荷分析结果表明,7种氧空位形成能均明显提升,且第一配位氧平均巴德电荷从1.13 e升至1.18 e,抑制了不稳定氧析出;锂化前后氧原子巴德电荷改变量从0.51 e降至0.11 e,表明循环前后的体系均具有良好的氧框架稳定性.通过差分电荷密度计算,发现Mo能够在Li去除后提供电荷补偿,而且Mo掺杂后锂离子迁移速率得到了提升,最低势垒从0.55 eV降至0.42 eV.为高价元素掺杂锂离子电池正极材料奠定了坚实的理论依据.Density functional theory(DFT)first-principles calculations were employed to elucidate the stabilization mechanism of lithium-rich manganese-based materials through Mo substitution for Mn.Mo doping mitigated the volume change rate,decreasing it from‒2.95%to‒0.53%and improved lattice distortion both before and after lithia⁃tion.Results from vacancy formation energy and Bader charge analysis revealed a marked increase in the formation energy of seven oxygen vacancies,and the average Bader charge of the first-coordination oxygen escalated from 1.13 e to 1.18 e,which effectively suppressed unstable oxygen precipitation.The change in Bader charge of oxygen atoms before and after lithiation decreased from 0.51 e to 0.11 e,which was indicative of the robust stability of the oxygen framework during cycling.Differential charge density calculations illustrated that Mo can compensate for charge after the removal of Li.Furthermore,Mo doping enhanced lithium ion migration rates,reducing the minimum barrier from 0.55 eV to 0.42 eV.This study provides a rigorous theoretical foundation for the doping of high-valence elements in lithium-ion battery cathode materials.

关 键 词：锂离子电池 富锂正极材料 电子性质 晶格氧 密度泛函理论 

分 类 号：O641[理学—物理化学]