CAREER: Electro-Chemo-Mechanics of Polymer/Active Material Interface Fracture

该学院早期职业发展（Career）计划研究项目旨在为几乎所有现有的和许多新兴的可充电电池化学物质中发现的聚合物/活性材料界面的断裂行为提供基本和定量的理解。这些界面的机械完整性对于维持电池系统中的电化学反应至关重要；因此，它决定了电池的长期性能（或耐用性）。聚合物/活性颗粒界面的断裂电隔离了活性颗粒，是电池容量衰减的主要机制之一，但这种界面失效的机制是人们了解得最少的问题。此外，电池的界面更加复杂，其性质不断变化。在这里开发的新型原位技术和断裂准则将有助于验证多物理场电池模型，并为新兴电池技术开发新的电极材料设计，这些技术可以改变汽车、生物医学、航空航天和军事等对耐久性有重要要求的领域。综合教育计划包括为新泽西理工大学的学生开发一个实验室模块，演示电化学循环过程中应力产生的过程（机械损伤的原因）。该模块将被修改并适应为K-12学生和教师的拓展计划。该奖项还使纽瓦克学校系统的小学教师培训生能够参与研究。聚合物/活性材料界面断裂一直是阻碍下一代电池电极（如Si、Sn、Al和其他大体积变化材料）快速发展的主要障碍。为了应对这些挑战，将新型的原位断裂实验和支持模型相结合，将提供对电池工作过程中界面特性如何演变的基本理解，并了解影响界面断裂行为的化学力学因素。为了使研究工作更加集中，锂离子电池的界面系统被认为是一个模型系统。断裂力学框架与界面本构模型，可以结合现场观察，将开发用于预测界面在电化学反应中的破坏。该研究将利用断裂力学模型对机械和电化学同时载荷下的界面破坏进行预测；因此，它为开发用于各种应用的长循环寿命、低成本和耐用电池奠定了基础。

This Faculty Early Career Development (CAREER) Program research project aims to provide a fundamental and quantitative understanding of the fracture behavior of polymer/active material interfaces that are found in almost all existing and many emerging rechargeable battery chemistries. The mechanical integrity of these interfaces is critical for sustaining electrochemical reactions in the battery systems; consequently, it dictates the long-term performance (or durability) of batteries. Fracture of the polymer/active particle interface electrically isolates active particles and is one of the predominant mechanisms by which capacity fade occurs in batteries, yet the mechanics of this interface failure is the least understood problem. Also, the interfaces in batteries are more complex and their properties change continuously. The novel in situ techniques and fracture criterion developed here will be useful in the validation of multi-physics battery models and development of new electrode material designs for emerging battery technologies that can transform automotive, biomedical, aerospace, and military applications where durability is an important requirement. The integrated education plan includes development of a lab module for students at NJIT that demonstrates the process of stress generation (cause of mechanical damage) during electrochemical cycling processes. This module will be modified and adapted into outreach programs for K-12 students and teachers. This award also enables elementary teacher trainees from the Newark school system to participate in the research. The polymer/active material interface fracture has been a major roadblock for the rapid advancement of next generation battery electrodes such as Si, Sn, Al, and other large volume change materials. To address these challenges, a combination of novel in situ fracture experiments and supporting models will provide a fundamental understanding of how the interface properties evolve during battery operation and to understand the chemo-mechanical factors that influence the interface fracture behavior. To keep the effort more focused, the interface system in lithium-ion batteries is considered as a model system. A fracture mechanics framework with an interface constitutive model that can incorporate in situ observations, will be developed for prediction of interface failure during an electrochemical reaction. This research will enable interface failure prediction under concurrent mechanical and electrochemical loading using the fracture mechanics models; hence, it lays the groundwork for the essential fundamental understanding to develop long cyclic life, low-cost, and durable batteries for a diverse range of applications.