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Understanding rapid charge and discharge in nano-structured lithium iron phosphate cathodes

Understanding rapid charge and discharge in nano-structured lithium iron phosphate cathodes
Understanding rapid charge and discharge in nano-structured lithium iron phosphate cathodes

A Doyle-Fuller-Newman (DFN) model for the charge and discharge of nano-structured lithium iron phosphate (LFP) cathodes is formulated on the basis that lithium transport within the nanoscale LFP electrode particles is much faster than cell discharge, and is therefore not rate limiting. We present some numerical solutions to the model and show that for relevant parameter values, and a variety of C-rates, it is possible for sharp discharge fronts to form and intrude into the electrode from its outer edge(s). These discharge fronts separate regions of fully utilised LFP electrode particles from those that are not. Motivated by this observation an asymptotic solution to the model is sought. The results of the asymptotic analysis of the DFN model lead to a reduced order model, which we term the reaction front model (or RFM). Favourable agreement is shown between solutions to the RFM and the full DFN model in appropriate parameter regimes. The RFM is significantly cheaper to solve than the DFN model, and therefore has the potential to be used in scenarios where computational costs are prohibitive, e.g. in optimisation and parameter estimation problems or in engineering control systems.

Lithium Iron Phosphate, Lithium-ion battery, Matched Asymptotic Expansions, Newman Model, Porous Electrode Theory, Reduced Order Model
0956-7925
328-368
Castle, M.
cc80c50c-dacd-4092-8d0b-76fde2f77563
Richardson, G.
3fd8e08f-e615-42bb-a1ff-3346c5847b91
Foster, J. M.
0786436b-150f-4b67-bd8c-126dbfce76bb
Castle, M.
cc80c50c-dacd-4092-8d0b-76fde2f77563
Richardson, G.
3fd8e08f-e615-42bb-a1ff-3346c5847b91
Foster, J. M.
0786436b-150f-4b67-bd8c-126dbfce76bb

Castle, M., Richardson, G. and Foster, J. M. (2021) Understanding rapid charge and discharge in nano-structured lithium iron phosphate cathodes. European Journal of Applied Mathematics, 33, 328-368. (doi:10.1017/S0956792521000036).

Record type: Article

Abstract

A Doyle-Fuller-Newman (DFN) model for the charge and discharge of nano-structured lithium iron phosphate (LFP) cathodes is formulated on the basis that lithium transport within the nanoscale LFP electrode particles is much faster than cell discharge, and is therefore not rate limiting. We present some numerical solutions to the model and show that for relevant parameter values, and a variety of C-rates, it is possible for sharp discharge fronts to form and intrude into the electrode from its outer edge(s). These discharge fronts separate regions of fully utilised LFP electrode particles from those that are not. Motivated by this observation an asymptotic solution to the model is sought. The results of the asymptotic analysis of the DFN model lead to a reduced order model, which we term the reaction front model (or RFM). Favourable agreement is shown between solutions to the RFM and the full DFN model in appropriate parameter regimes. The RFM is significantly cheaper to solve than the DFN model, and therefore has the potential to be used in scenarios where computational costs are prohibitive, e.g. in optimisation and parameter estimation problems or in engineering control systems.

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nanoLFP_resubmission - Accepted Manuscript
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Accepted/In Press date: 25 January 2021
e-pub ahead of print date: 1 March 2021
Keywords: Lithium Iron Phosphate, Lithium-ion battery, Matched Asymptotic Expansions, Newman Model, Porous Electrode Theory, Reduced Order Model

Identifiers

Local EPrints ID: 448470
URI: http://eprints.soton.ac.uk/id/eprint/448470
ISSN: 0956-7925
PURE UUID: 12427ad7-cb84-49c7-bba9-dcb155d8b208
ORCID for G. Richardson: ORCID iD orcid.org/0000-0001-6225-8590

Catalogue record

Date deposited: 22 Apr 2021 16:47
Last modified: 17 Mar 2024 06:28

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Contributors

Author: M. Castle
Author: G. Richardson ORCID iD
Author: J. M. Foster

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