GOALI: Understanding and Predicting Li Dendrite Formation in Li-ion Batteries

该基金的研究目的是从根本上了解锂电池中锂金属枝晶形成的热力学驱动力和动力学机制。锂离子电池设计面临的最大挑战之一是防止锂树枝晶生长，这将使当前的锂离子电池技术更快地充电，并在未来的“超越锂离子电池”中使用锂金属阳极。建立了一个基于相场方法的计算模型，用原子/第一原理计算和实验测量的热力学、力学和动力学参数来预测枝晶生长和形态变化的条件。该模型将基于一个非线性动力学模型，其中相场参数的变化率与热力学驱动力的关系是非线性的，因此适用于大过电位或高充电率下的微结构演化模拟。其中一个关键参数是Li金属/电解液界面能，通过结合密度泛函理论计算和液体热力学数据直接计算得到。这项为期三年的资助将导致(1)对树枝晶形成和生长的输运和化学动力学及其与固体电解质界面(SEI)膜性能的关系的基本了解，(2)开发基于物理的微结构演变模型，该模型不依赖不可转移的拟合参数来预测树枝晶形成和生长的条件。这项工作的最终目标是消除或至少限制枝晶在锂金属电极上的形成。枝晶的形成是锂电池的主要退化和失效机制，也是一个安全问题，要么是因为枝晶碎片与锂电极的其余部分失去电接触，要么是因为生长的树枝晶穿透隔板而导致短路。从这项研究计划中获得的基本认识预计将有助于锂离子电池安全性的提高，这是混合动力汽车和电动汽车近期发展的迫切需要。计划中的研究，无论是方法还是实际结果，都旨在通过提供关于电极材料在各种电化学条件下的行为的重要基础信息，为新的电池技术做出重大贡献。转基因科学家的直接参与为传播该项目产生的知识提供了一个重要途径。除了同行评议的出版物和会议记录外，主要的研究成果还将在http://lithiumbatteryresearch.com/上与公众在线分享。该项目支持的研究生和博士后将在工业环境中度过更长的一段时间，这将为他们的教育提供一个重要的补充维度。因此，这两个人都将为未来电池相关领域的工作做好准备。此外，本科生将通过宾夕法尼亚州立大学的Mure(少数族裔本科生研究经验)计划和宾夕法尼亚州立大学材料科学与工程系的高级论文项目成为该项目的组成部分。

The research objective of this grant is to fundamentally understand the thermodynamic driving forces and kinetic mechanisms leading to the formation of lithium metal dendrites in Li-batteries. One of the most significant challenges for Li-ion battery design is the prevention of Li-dendrite growth, which would allow faster charging for current Li-ion battery technology and the use of Li metal anodes for future "beyond Li-ion batteries." A computational model based on the phase-field method will be developed to predict the conditions for dendrite growth and morphological changes with input thermodynamic, mechanical and kinetic parameters from atomistic/first principles calculations and experimental measurements. The proposed model will be based on a nonlinear kinetics in which the dependence of the rate of changes of a phase-field parameter is nonlinear with respect to the thermodynamic driving force, and hence it is applicable to modeling the microstructure evolution under large overpotentials or high charging rates. One of the key parameters is the Li metal/electrolyte interface energy, which will be directly computed by connecting DFT calculations and liquid thermodynamic data. This three-year grant will lead to (1) fundamental understanding of the transport and chemical kinetics of dendrite formation and growth and their relationships to their solid electrolyte interphase (SEI) film properties and (2) the development of a physics-based microstructure evolution model that does not rely on non-transferable fitting parameters to predict the conditions for dendrite formation and growth morphology. The ultimate goal for this work is to eliminate the formation-- or at least to limit the growth-- of dendrites on Li metal electrodes.Dendrite formation is the primary degradation and failure mechanism and a safety concern in Li batteries, either because dendrite pieces lose electrical contact with the rest of the Li electrode or because growing dendrites penetrate the separator and lead to short circuits. The fundamental understanding achieved from this research program is expected to contribute to the Li ion battery safety improvement, a critical need for the near-term development of hybrid and electric vehicles. The planned research, both the methodology and the actual results, are designed to make significant contributions to new battery technology by providing important fundamental information about electrode materials behavior under various electrochemical conditions. The direct involvement of GM scientists provides an important avenue for disseminating the knowledge generated from this project. The primary research results will be shared with the public on-line to the public at http://lithiumbatteryresearch.com/ in addition to peer-reviewed publication and conference proceedings. The graduate student and postdoc supported by this project will spend extended periods of time in an industrial environment, which will provide an important added dimension to their education. Both of these individuals will thus be very well positioned for future work in battery-related fields. In addition, undergraduate students will be integral to the program via Penn State's MURE (Minority Undergraduate Research Experience) programs and senior thesis projects in the Department of Materials Science and Engineering at Penn State.