Date of Award

Fall 2021

Document Type

Open Access Dissertation

Department

Chemical Engineering

First Advisor

John W. Weidner

Second Advisor

Sirivatch Shimpalee

Abstract

As the automotive industry moves towards large format electric vehicles, such as trucks and SUVs, the need for highly efficient, energy-dense electrodes rapidly increases. Several promising active materials have been studied and proposed, however, many of these materials undergo significant volume change upon lithiation and de-lithiation. Cell and pack designers struggle to understand and predict how active material volume change at the particle scale will affect mechano-electrochemical behavior on the electrode, cell, and pack scales. Additionally, many of these active materials suffer in their cycle life due to a mechanically-driven degradation of the electrode matrix. Therefore, the focus of this work is to develop a multi-scale model that accounts for relationships between mechanical and electrochemical phenomena at each scale in the battery system.

The resulting model establishes three novel improvements to the field of mechano-electrochemical battery modeling: (1) A representative volume element model was incorporated into standard battery models to generate realistic predictions of mechanical behavior in the battery cell and pack. (2) Thermodynamically non-ideal, lithiation-based volume change behavior of the active materials was accounted for in the model, leading to higher accuracy in simulations of pressure and cell strain and a stronger understanding of how anode/cathode capacity balance impacts volume change. And (3) a mechano-electrochemical model of a blended electrode was developed, bringing a better understanding of how active materials preferentially lithiate and the resulting effects on mechano-electrochemical behavior of the cell.

Rights

© 2021, Drew J. Pereira

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