Stress Evolution in Na-Ion Battery Anode during Electrochemical Cycling

Abstract

A large amount of literature exists on the electrochemical characterization of various high capacity sodium-ion battery electrodes; however, their mechanical behavior has not been characterized before. In this study, evolution of stress in sodium-ion battery electrode has been measured in real-time using an optical-based substrate curvature measurement apparatus. A 100 nm Ge thin film, as working electrode, was cycled against sodium reference/counter electrode with 1 M sodium perchlorate (NaClO4) in propylene carbonate (PC) as electrolyte. Electrochemical and stress response of the electrodes to the prescribed electrochemical cycling conditions were measured simultaneously. Further, the sodiated Ge samples were analyzed using SEM, XRD, and AFM techniques to understand the microstructural changes. It was observed that sodiation of Ge films resulted in distinctly different mechanics and electrochemical phenomenon compared to that of lithiated Ge films. These observations and implications will be further discussed in the talk.