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Insight in to the defect model, Li+ diffusion mechanism and doping level dependency of Li+ doping BPO4 by first principles and molecular dynamics method
Solid State Ionics ( IF 3.0 ) Pub Date : 2020-09-24 , DOI: 10.1016/j.ssi.2020.115465
Yuting Xie , Qinyun Wang , Fanpei Gu , Miao Shui , Jie Shu

In this article, two defect models of LixB1-x/3PO4, LiB″ + 2Li model and VB‴ + 3Li model, are fully evaluated by means of density function theory (DFT), bond-valence-energy-landscape mapping (BVEL) and molecular dynamics (MD). LiB″ + 2Li model is more stable and is the dominant defect model at low temperatures. The Li+ diffusion mechanism for LiB″ + 2Li model is revealed where LiB′′ mediated diffusion along a/b axis owns the lowest energy barrier of 0.35 eV. Li+ doping level dependency of Li+ diffusion coefficient is obtained by molecular dynamics simulation of LixB1-x/3PO4 with multiple doping levels, which exhibits better ionic conductivities within the range of 0.093–0.28, with the highest DLi+ of 1.45 × 10−9 cm2∙s−1 at x = 0.187. Basically, all the activation energy components increase slowly with the augmentation of Li+ doping level except the lowest doping level 0.049 and they reach their respective minimum at x = 0.093.



中文翻译:

通过第一原理和分子动力学方法洞察缺陷模型,Li +扩散机理和Li +掺杂BPO 4的掺杂水平依赖性

在本文中,李两个缺损模型X1- X / 3 PO 4,李“+ 2LI模型和V'''+ 3Li模型,通过密度函数理论的手段(DFT)的完全计算,键valence-能量-景观映射(BVEL)和分子动力学(MD)。Li B ''+ 2Li模型更稳定,是低温下的主要缺陷模型。李+为Li扩散机制显露“+ 2LI模型,其中锂'沿A / B轴扩散介导的拥有0.35电子伏特的最低能量势垒。李+锂的掺杂浓度依赖性+通过分子动力学模拟获得多个掺杂水平的Li x B 1- x / 3 PO 4的扩散系数,该离子在0.093–0.28的范围内具有更好的离子电导率,最高的D Li +为1.45×10 -9  cm 2小号-1X  = 0.187。基本上,除了最低掺杂水平0.049以外,所有活化能组分都随着Li +掺杂水平的增加而缓慢增加,并且在x  = 0.093时达到各自的最小值。

更新日期:2020-09-24
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