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

该研究项目的研究目标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枝晶生长，这将使目前的锂离子电池技术能够更快地充电，并将锂金属阳极用于未来的“超越锂离子电池”。“将开发一种基于相场方法的计算模型，通过原子/第一性原理计算和实验测量输入的热力学、机械和动力学参数来预测枝晶生长和形态变化的条件。 所提出的模型将基于非线性动力学，其中相场参数的变化率的依赖性相对于热力学驱动力是非线性的，因此它适用于模拟大过电位或高充电速率下的微观结构演变。 关键参数之一是Li金属/电解质界面能，其将通过连接DFT计算和液体热力学数据来直接计算。 这项为期三年的资助将导致（1）对枝晶形成和生长的运输和化学动力学及其与固体电解质界面（SEI）薄膜特性的关系的基本理解，以及（2）开发基于物理的微观结构演化模型，该模型不依赖于不可转移的拟合参数来预测枝晶形成和生长形态的条件。 这项工作的最终目标是消除锂金属电极上枝晶的形成--或者至少限制枝晶的生长。枝晶的形成是锂电池中主要的退化和失效机制，也是一个安全问题，因为枝晶碎片与锂电极的其余部分失去电接触，或者因为生长的枝晶穿透隔膜并导致短路。 从这项研究计划中获得的基本理解预计将有助于提高锂离子电池的安全性，这是混合动力和电动汽车近期发展的关键需求。 计划中的研究，无论是方法还是实际结果，都旨在通过提供有关电极材料在各种电化学条件下行为的重要基础信息，为新电池技术做出重大贡献。 转基因科学家的直接参与为传播这一项目产生的知识提供了重要途径。 除了同行评审的出版物和会议记录外，主要研究结果将在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较长的时间，这将为他们的教育提供一个重要的附加维度。 因此，这两个人将非常适合未来在电池相关领域的工作。 此外，本科生将通过宾夕法尼亚州立大学的MURE（少数民族本科生研究经验）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计划的组成部分。

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.