Modelling charge transport in lithium-Ion batteries

Abstract

Lithium-ion batteries are highly considered for rechargeable storage devices due to their competitive theoretical capacities and energy densities; they have shown great potential for use in electric and hybrid vehicles. Having already found use in smaller portable devices, research now pushes to increase their efficiency through the use of models to better understand the processes occurring and by studying materials for new designs. In this thesis, we first focus on the charge transport occurring within the electrolyte before considering the intercalation of lithium within electrode particles. We begin by giving an overview of the structure and current development of a lithium-ion battery before discussing the equations to describe the movements of ions in the electrolyte phase. We discuss the application of these equations to a dilute electrolyte and then introduce moderately concentrated electrolyte theory, where we now consider the interactions between ions. We present an ion-hopping model using a Monte Carlo algorithm to simulate these ionic interactions and the effect on their movements. We use this model to find the activity coefficients of electrolytes composed of LiP F₆ using various solvents. We discuss single-particle models and how they can be used to simplify computationally intensive models such as the Doyle-Fuller-Newman model. A study of quantum tunnelling and solving the Schrodinger equation is presented, which we apply to LiF eP O₄ and LiCoO₂ cathodes to investigate electron tunnelling as a potential cause of electrode degradation and electrolyte decomposition.

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Identifiers

ORCID for Ethan Culverhouse: orcid.org/0009-0005-3528-1812

ORCID for Giles Richardson: orcid.org/0000-0001-6225-8590

ORCID for Christopher Howls: orcid.org/0000-0001-7989-7807

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