Towards Optimised Cell Design of Thin Film Silicon-Based Solid-State Batteries via Modelling and Experimental Characterisation

Pooja Vadhva, Adam M. Boyce, Alastair Hales, Mei Chin Pang, Anisha N. Patel, Paul R. Shearing, Gregory Offer, Alexander J.E. Rettie

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)

Abstract

To realise the promise of solid-state batteries, negative electrode materials exhibiting large volumetric expansions, such as Li and Si, must be used. These volume changes can cause significant mechanical stresses and strains that affect cell performance and durability, however their role and nature in SSBs are poorly understood. Here, a 2D electro-chemo-mechanical model is constructed and experimentally validated using steady-state, transient and pulsed electrochemical methods. The model geometry is taken as a representative cross-section of a non-porous, thin-film solid-state battery with an amorphous Si (a-Si) negative electrode, lithium phosphorous oxynitride (LiPON) solid electrolyte and LiCoO2 (LCO) positive electrode. A viscoplastic model is used to predict the build-up of strains and plastic deformation of a-Si as a result of (de)lithiation during cycling. A suite of electrochemical tests, including electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique and hybrid pulse power characterisation are carried out to establish key parameters for model validation. The validated model is used to explore the peak interfacial (a-Si∣LiPON) stress and strain as a function of the relative electrode thickness (up to a factor of 4), revealing a peak volumetric expansion from 69% to 104% during cycling at 1C. The validation of this electro-chemo-mechanical model under load and pulsed operating conditions will aid in the cell design and optimisation of solid-state battery technologies.

Original languageEnglish
Article number100525
JournalJournal of the Electrochemical Society
Volume169
Issue number10
DOIs
Publication statusPublished - 19 Oct 2022

Bibliographical note

Funding Information:
We thank Ilika Technologies Ltd for providing us with cells and helpful discussions, in particular to Dr Chris Vian. We also thank Dr Ruben Tomlin for his work developing a MATLAB tool to fit the equivalent circuit model parameters in the presented stud We gratefully acknowledge an EPSRC DTP Studentship (EP/R513143/1) and the Faraday Institution [EP/S003053/1, grant numbers: FIRG015, FIRG0026] for funding and UCL for start-up funds. PRS acknowledges the support of The Royal Academy of Engineering (CIET1718/59)

Publisher Copyright:
© 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.

Keywords

  • elastic
  • finite element analysis model
  • plastic
  • pulse testing
  • silicon anode
  • solid-state battery

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