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.