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

这一学院早期职业发展(CALEAR)计划研究项目旨在提供对聚合物/活性材料界面断裂行为的基本和定量的了解，这些界面存在于几乎所有现有的和许多新兴的充电电池化学中。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/活性粒子界面的断裂电隔离了活性粒子，是电池容量衰减的主要机制之一，但这种界面失效的机理是人们最不了解的问题。此外，电池中的界面更加复杂，其性能也不断变化。这里开发的新的原位技术和断裂准则将有助于验证多物理电池模型，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、航空航天和对耐用性有重要要求的军事应用。综合教育计划包括为NJIT的学生开发一个实验模块，演示在电化学循环过程中应力产生的过程(机械损伤的原因)。这一单元将被修改并改编成面向K-12学生和教师的外展方案。该奖项还允许纽瓦克学校系统的小学教师实习生参与研究。聚合物/活性材料界面断裂一直是阻碍硅、锡、铝等大体积变化材料等下一代电池电极快速发展的主要障碍。为了应对这些挑战，新颖的原位断裂实验和支持模型的结合将提供对电池运行过程中界面属性如何演变的基本理解，并了解影响界面断裂行为的化学机械因素。为了使研究更有针对性，将锂离子电池的界面系统作为模型系统。为了预测电化学反应过程中的界面失效，将开发一个具有界面本构模型的断裂力学框架，该模型可以结合现场观测。这项研究将使用断裂力学模型预测机械和电化学同时加载下的界面失效；因此，它为开发适用于各种应用的长循环寿命、低成本和耐用电池奠定了必要的基础。

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.