Molecular dynamics simulations of spinels: LiMn2O4 and Li4Mn5O12 at high temperatures

12th Europhysical Conference on Defects in Insulating Materials

材料科学;物理学

Ledwaba, R.S.^1 ; Matshaba, M.G.^1 ; Ngoepe, P.E.^1

Materials Modelling Centre, University of Limpopo, Private Bag X 1106, Sovenga

0727, South Africa^1

关键词: Energy storage technologies;    Exponential increase;    Intercalation hosts;    Lithium Intercalation;    Lithium ion diffusion;    Molecular dynamics simulations;    Structural behaviour;    Structural stabilities;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/80/1/012024/pdf
DOI  :  10.1088/1757-899X/80/1/012024

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Spinel lithium manganates have attracted attention due to their electrochemical properties and also as promising cathode materials for lithium-ion batteries. The current study focused on the effects of high temperatures on the materials, in order to understand the sustainability in cases where the battery heats up to high temperature and analysis of lithium diffusion aids in terms of intercalation host compatibility. It is also essential to understand the high temperature behaviour and lithium ion host capability of these materials in order to perform the armorphization and recrystalization of spinel nano-architectures. Molecular dynamics simulations carried out to predict high temperature behaviour of the spinel systems. The NVE ensemble was employed, in the range 300 - 3000K. The melting temperature, lithium-ion diffusion and structural behaviour were monitored in both supercell systems. LiMn2O4indicated a diffusion rate that increased rapidly above 1500K, just before melting (∼1700K) and reached its maximum diffusion at 2.756 10-7cm2s-1before it decreased. Li4Mn5O12indicated an exponential increase above 700K reaching 8.303 10-7cm2s-1at 2000K and allowing lithium intercalation even above its melting point of around 1300K. This indicated better structural stability of Li4Mn5O12and capability to host lithium ions at very high temperatures (up to 3000 K) compared to LiMn2O4.