摘要
与大多数的锂电池正极材料相比,晶尖石结构LiMn_(2)O_(4)正极材料价格便宜、工作电压高、稳定性能好和安全性能高。但是,其在充电过程中电池的容量快速衰减、对高温很敏感和易发生不良的化学反应,因此在极大范围内阻碍了其大规模的商业化发展。为了进一步改善LiMn_(2)O_(4)正极材料的循环稳定性以满足市场需求,正确了解微观结构原子性能至关重要。在本研究中,在LiMn_(2)O_(4)正极材料中分别掺入Ni^(2+)、Al^(3+),使用密度泛函理论研究尖晶石结构中Li^(+)性质和锂空位的迁移壁垒。通过对LiMn_(2)O_(4)总能量与晶格常数、总态密度的计算分析,结果表明,LMO中Mn原子被各种阳离子X(LXM)取代会导致影响Li迁移率的结构变化。计算出元素替换后的迁移空位活化能在0.32eV~0.57eV之间变化,对于在LMO中迁移间隙,计算出约0.72 eV迁移能。然而,被Ni和Al元素取代会引入间隙Li+进行电荷补偿,稳定了尖晶石结构,提高了LMO的离子传输。
Compared with most lithium battery cathode materials,spinel Li Mn2 O4 cathode materials have the advantages of low price,high working voltage,good stability and safety.However,in the process of charge and discharge,its specific capacity decays rapidly,it is not resistant to high temperature,and it is prone to Jahn-teller distortion effect,which hinders its largescale commercial development to a great extent.In order to further improve the cycle stability of LiMn_(2)O_(4) cathode material to meet the market demand,it is very important to correctly understand the microstructure and atomic properties.In this paper,we doped Ni^(2+) and Al^(3+) into LiMn_(2)O_(4) cathode materials respectively,studied the lithium ion properties and lithium vacancy migration barriers in spinel structure by using density functional theory,and calculated and analyzed the total energy,lattice constant and total density of states of LiMn_(2)O_(4).The results show that the substitution of Mn atoms by various cations x(LXM) in LMO will lead to structural changes affecting Li mobility.The migration vacancy activation energy after element replacement is calculated to vary between 0.32 eV and 0.57 eV.For the migration gap in LMO,the migration energy is calculated to be about 0.72 e V.However,the substitution of Ni and Al elements will introduce interstitial Li ions for charge compensation,stabilize the spinel structure and improve the ion transport of LMO.
作者
伍澎贵
姜兴涛
张宇
宁玉娟
黄东雪
梁兴华
WU Penggui;JIANG Xingtao;ZHANG Yu;NING Yujuan;HUANG Dongxue;LIANG Xinghua(School of Mechanical and Traffic Engineering,Guangxi University of Science and Technology,Liuzhou Guangxi 545006,China)
出处
《装备制造技术》
2021年第10期10-14,共5页
Equipment Manufacturing Technology
基金
国家自然科学基金项目(52161033)
广西自然科学基金项目(2020GXNSFAA297082)
广西创新驱动发展专项资金项目(桂科AA18242036-2)。
关键词
循环稳定
微观结构
密度泛函理论
活化能
离子传输
cyclic stability
micro structure
density functional theory
activation energy
ion transport
作者简介
伍澎贵(1997-),男,广西玉林人,在读硕士研究生,研究方向:新能源汽车动力电池及材料;通信作者:梁兴华,博士,副教授,研究方向:新能源汽车动力电池及材料。
