Date of Award

1-1-2013

Document Type

Open Access Thesis

Department

Chemical Engineering

First Advisor

John W Weidner

Second Advisor

Xinyu Huang

Abstract

Electrochemical devices (batteries, fuel cell) are expected to play a vital role in the future of energy consumption for various purposes ranging from house hold usage to space exploration. Research is being conducted on various aspects so as to improve the design and operating range of these devices and one of the primary focuses is the porous electrode. It has been reported that significant volume change can occur during electrode processes, within the porous electrodes and depending on the material it can be as high as, but not limited to 300%. These large volume changes along with product formation in pores can cause severe mechanical and performance degradation. However, prediction of stresses generated inside the electrode is highly empirical. Predictive models could give crucial insight into design parameters. Here we have formulated a continuum presentation of the porous material which combines mechanics of the solid phase of the porous material with the dependence of porosity on stress, as in rock-mechanics. In this new model, the deformation of the porous electrode material is characterized by its compressibility. Using the analogy between thermal stress-strain relationships and stress-strain relationship for existing concentration gradients, a constitutive law for the volumetric strain of the electrode during intercalation is developed, facilitating the prediction of volume and porosity change from fundamental material properties. The model is general and in conjunction with appropriate boundary and initial conditions, can be used to predict the volume and porosity change of any electrode during operation.

Rights

© 2013, Kumud Kanneganti

Download

Share

COinS