From Atomistic to Continuum Models of Interfaces in Lithium-Ion Batteries

锂离子电池界面从原子模型到连续体模型

• 批准号: 2119790
• 金额: --
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2119790
• 关键词: Atomistic; Continuum; Models; Interfaces; Lithium

Modelling Li transport through Li-ion solid-state electrolytes is important for predicting their performances. These materials are often polycrystalline and have interfaces which significantly affect Li transport through the material. Therefore, it is vital to be able to model the effect of these grain batteries in order to fully explore potential new materials to be used in Li-ion batteries.The conventional method of modelling ionic transport across grain boundaries involves solving the Poisson-Boltzmann equation to find the equilibrium distri- bution of point defects (e.g. Li interstitials and vacancies) in a 1D continuum model. This approach assumes defects interact only through mean-field electro- statics, and corresponds to modelling the dilute limit of defect concentrations. Where here, structural defects include ion vacancies and dopant ions. In bat- tery materials, where defect concentrations can be high, interactions between these defects are more complex than the dilute limit mean-field description. To develop accurate models of the effects of grain boundaries on lithium-ion trans- port in these materials, it is therefore necessary to go beyond the dilute limit approximation.The project will involve investigating the thermodynamics of the problem in order to try to incorporate an additional concentration dependent term to the chemical potential. Attempts of producing a model that incorporates the inter- actions between structural defects in solid state electrolytes have been made, however these methods are not widely accepted at the present time, due to the lack of a method for calculating the key parameters for these models [1]. After the form of this additional term is determined, methods of calculating coefficients for such a term for individual grain boundaries and materials will be required. This will require investigating the fundamental thermodynamics of the problem further and determining which calculations are required in order to obtain the values of these parameters a priori. An alternative approach whereby chemical activities are used in order to minimise the free energy of the entire system will also be explored.Throughout the project, the existing code (written and developed by the pre- vious PhD candidate, Georgina Wellock) will be improved and altered to meet the requirements of the new thermodynamics of the problem or to improve efficiency.References[1] Mebane D. S. and De Souza R. A.; Energy Environ. Sci. 2015, 8, 2935-2940.

通过锂离子固态电解质对LI转运进行建模对于预测其性能很重要。这些材料通常是多晶的，并且具有显着影响Li通过材料的li传输的界面。因此，至关重要的是，能够对这些谷物电池的效果进行建模，以充分探索要在锂离子电池中使用的潜在新材料。对跨晶界进行离子传输进行建模的传统方法涉及求解Poisson-Boltzmann方程，以使点缺陷的平衡分散分布（E.G. li interstities and interstities and interstities and interstities and Interstities and Interstities and Interstities and Interstities and Interstities and Interstities and Interstities）该方法假设缺陷仅通过平均场电静电量相互作用，并且对应于对缺陷浓度的稀释极限进行建模。在这里，结构缺陷包括离子空位和掺杂离子。在蝙蝠的材料中，缺陷浓度可能很高，这些缺陷之间的相互作用比稀数极限场描述更为复杂。为了开发晶界对这些材料中锂离子转移的影响的准确模型，因此有必要超越稀数极限近似。已经进行了一种模型的尝试，该模型已经进行了固态电解质中的结构缺陷之间的相互作用，但是由于缺乏计算这些模型的关键参数的方法，目前并未广泛接受这些方法[1]。确定此附加项的形式后，将需要计算该术语的系数的方法和材料。这将需要进一步研究问题的基本热力学，并确定需要哪些计算才能先验获得这些参数的值。使用化学活动以最大程度地减少整个系统的自由能的一种替代方法也将被探索。该项目将改善并改善现有的代码（由曾经的博士学位候选者Georgina Wellock编写和开发）。能源环境。科学。 2015，8，2935-2940。