Coupled Electrochemical-Thermal-Mechanical Stress Modelling in Composite Silicon/Graphite Lithium-Ion Battery Electrodes

17 Pages Posted: 15 Mar 2023

See all articles by Mayur Prakash Bonkile

Mayur Prakash Bonkile

Imperial College London

Yang Jiang

Imperial College London

Niall Kirkaldy

Imperial College London

Valentin Sulzer

University of Michigan - Department of Mechanical Engineering

Robert Timms

University of Oxford

Huizhi Wang

Imperial College London - Department of Mechanical Engineering

Gregory Offer

Imperial College London

Billy Wu

Imperial College London

Abstract

Silicon is often added to graphite battery electrodes to enhance the electrode-specific capacity, but it undergoes significant volume changes during (de)lithiation, which results in mechanical stress, fracture, and performance degradation. To develop long-lasting and energy-dense batteries, it is critical to understand the non-linear stress behaviour in composite silicon-graphite electrodes. In this study, we developed a coupled electrochemical-thermal-mechanical model of a composite silicon/graphite electrode in PyBaMM (an open-source physics-based modelling platform). The model is experimentally validated against a commercially available LGM50T battery, and the effects of C-rates, depth-of-discharge (DoD), and temperature are investigated. The developed model can reproduce the voltage hysteresis from the silicon and provide insights into the stress response and crack growth/propagation in the two different phases. The stress in the silicon is relatively low at low DoD but rapidly increases at a DoD >∼80%, whereas the stress in the graphite increases with decreasing temperature and DoD. At higher C-rates, peak stress in the graphite increases as expected, however, this decreases for silicon due to voltage cutoffs being hit earlier, leading to lower active material utilisation since silicon is mostly active at high DoD. Therefore, this work provides an improved understanding of stress evolution in composite silicon/graphite lithium-ion batteries.

Keywords: Composite negative electrodes, Silicon/graphite, Stress generation, Particle cracking, Lithium-ion battery, Physics-based model

Suggested Citation

Bonkile, Mayur Prakash and Jiang, Yang and Kirkaldy, Niall and Sulzer, Valentin and Timms, Robert and Wang, Huizhi and Offer, Gregory and Wu, Billy, Coupled Electrochemical-Thermal-Mechanical Stress Modelling in Composite Silicon/Graphite Lithium-Ion Battery Electrodes. Available at SSRN: https://ssrn.com/abstract=4389635 or http://dx.doi.org/10.2139/ssrn.4389635

Mayur Prakash Bonkile (Contact Author)

Imperial College London ( email )

South Kensington Campus
Exhibition Road
London, SW7 2AZ
United Kingdom

Yang Jiang

Imperial College London ( email )

South Kensington Campus
Exhibition Road
London, SW7 2AZ
United Kingdom

Niall Kirkaldy

Imperial College London ( email )

South Kensington Campus
Exhibition Road
London, SW7 2AZ
United Kingdom

Valentin Sulzer

University of Michigan - Department of Mechanical Engineering ( email )

Ann Arbor, MI 48109
United States

Robert Timms

University of Oxford ( email )

Mansfield Road
Oxford, OX1 4AU
United Kingdom

Huizhi Wang

Imperial College London - Department of Mechanical Engineering ( email )

Gregory Offer

Imperial College London ( email )

South Kensington Campus
Exhibition Road
London, SW7 2AZ
United Kingdom

Billy Wu

Imperial College London ( email )

South Kensington Campus
Exhibition Road
London, SW7 2AZ
United Kingdom

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