Modelling the current-dependent voltage behaviour of LFP batteries
This thesis investigates how a deliberately compact, TLM-inspired electrical model can reproduce the rate-dependent blurring of voltage plateaus in an LFP–graphite cell, while keeping complexity compatible with embedded applications. The focus is on moderate C-rates, where electrolyte and charge-tra...
| Autor: | |
|---|---|
| Formato: | tesis de maestría |
| Fecha de publicación: | 2025 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/449901 |
| Acesso em linha: | https://hdl.handle.net/2117/449901 |
| Access Level: | acceso abierto |
| Palavra-chave: | Lithium ion batteries Electric batteries -- Mathematical models Energy storage Bateries d'ió liti Bateries elèctriques -- Models matemàtics Energia -- Emmagatzematge Àrees temàtiques de la UPC::Energies Àrees temàtiques de la UPC::Enginyeria elèctrica |
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Modelling the current-dependent voltage behaviour of LFP batteriesGil Fernández, DavidLithium ion batteriesElectric batteries -- Mathematical modelsEnergy storageBateries d'ió litiBateries elèctriques -- Models matemàticsEnergia -- EmmagatzematgeÀrees temàtiques de la UPC::EnergiesÀrees temàtiques de la UPC::Enginyeria elèctricaThis thesis investigates how a deliberately compact, TLM-inspired electrical model can reproduce the rate-dependent blurring of voltage plateaus in an LFP–graphite cell, while keeping complexity compatible with embedded applications. The focus is on moderate C-rates, where electrolyte and charge-transfer polarisation dominate over solid diffusion, and on preserving graphite staging features under load. First, an anode-side submodel is constructed using a multi-branch transmission-line architecture. Four parallel branches, each with its own coulomb counter, pseudo-OCP source and Butler–Volmer element, share an ionic rail whose resistance is initially estimated from geometry, porosity and electrolyte conductivity. With this physics-based configuration, the model preserves the staging sequence in both lithiation and delithiation. Lithiation RMSE remains within the range of 4−11 mV up to C/3, whereas delithiation exhibits larger asymmetries. A single scalar optimisation of the effective ionic resistance, anchored at C/3 lithiation with a combined voltage and DVA cost, reduces lithiation RMSE to below about 9 mV across C/25–C/3 and improves the representation of rate-induced plateau broadening. The optimised anode model is then combined with a positive-electrode half-cell LUT. A Dubarry-style alignment using LRini and OF Sini defines a full-cell pOCV at C/25. A lumped series resistance Rfull-cell is subsequently identified by multi-rate fitting. This reduces charge RMSE to 8–13 mV and discharge RMSE to about 20 mV over C/25–C/3, while preserving plateau shapes and SoC transitions. Finally, the static maps are embedded in a dynamic ECM with one ohmic resistor and two R–C branches. The model is validated under a realistic load current profile that exceeds the nominal C/3 range and includes frequent current reversals. Under these conditions, the ECM attains a global RMSE of 14.2 mV and captures the timing of voltage peaks and valleys with reasonable fidelity. The analysis identifies the main limitations—coarse parameter grids, operation outside the calibrated C-rate window and simplified hysteresis—and outlines a path towards battery models that remain physically informed yet deployable for diagnostics and control.OutgoingUniversitat Politècnica de CatalunyaPérez González, Juan JesúsRubio Gómez, ManuelJossen, Andreas20252025-11-2520262026-01-09master thesishttp://purl.org/coar/resource_type/c_bdccNAhttp://purl.org/coar/version/c_be7fb7dd8ff6fe43info:eu-repo/semantics/masterThesisapplication/pdfhttps://hdl.handle.net/2117/449901reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/4499012026-05-27T15:37:01Z |
| dc.title.none.fl_str_mv |
Modelling the current-dependent voltage behaviour of LFP batteries |
| title |
Modelling the current-dependent voltage behaviour of LFP batteries |
| spellingShingle |
Modelling the current-dependent voltage behaviour of LFP batteries Gil Fernández, David Lithium ion batteries Electric batteries -- Mathematical models Energy storage Bateries d'ió liti Bateries elèctriques -- Models matemàtics Energia -- Emmagatzematge Àrees temàtiques de la UPC::Energies Àrees temàtiques de la UPC::Enginyeria elèctrica |
| title_short |
Modelling the current-dependent voltage behaviour of LFP batteries |
| title_full |
Modelling the current-dependent voltage behaviour of LFP batteries |
| title_fullStr |
Modelling the current-dependent voltage behaviour of LFP batteries |
| title_full_unstemmed |
Modelling the current-dependent voltage behaviour of LFP batteries |
| title_sort |
Modelling the current-dependent voltage behaviour of LFP batteries |
| dc.creator.none.fl_str_mv |
Gil Fernández, David |
| author |
Gil Fernández, David |
| author_facet |
Gil Fernández, David |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Pérez González, Juan Jesús Rubio Gómez, Manuel Jossen, Andreas |
| dc.subject.none.fl_str_mv |
Lithium ion batteries Electric batteries -- Mathematical models Energy storage Bateries d'ió liti Bateries elèctriques -- Models matemàtics Energia -- Emmagatzematge Àrees temàtiques de la UPC::Energies Àrees temàtiques de la UPC::Enginyeria elèctrica |
| topic |
Lithium ion batteries Electric batteries -- Mathematical models Energy storage Bateries d'ió liti Bateries elèctriques -- Models matemàtics Energia -- Emmagatzematge Àrees temàtiques de la UPC::Energies Àrees temàtiques de la UPC::Enginyeria elèctrica |
| description |
This thesis investigates how a deliberately compact, TLM-inspired electrical model can reproduce the rate-dependent blurring of voltage plateaus in an LFP–graphite cell, while keeping complexity compatible with embedded applications. The focus is on moderate C-rates, where electrolyte and charge-transfer polarisation dominate over solid diffusion, and on preserving graphite staging features under load. First, an anode-side submodel is constructed using a multi-branch transmission-line architecture. Four parallel branches, each with its own coulomb counter, pseudo-OCP source and Butler–Volmer element, share an ionic rail whose resistance is initially estimated from geometry, porosity and electrolyte conductivity. With this physics-based configuration, the model preserves the staging sequence in both lithiation and delithiation. Lithiation RMSE remains within the range of 4−11 mV up to C/3, whereas delithiation exhibits larger asymmetries. A single scalar optimisation of the effective ionic resistance, anchored at C/3 lithiation with a combined voltage and DVA cost, reduces lithiation RMSE to below about 9 mV across C/25–C/3 and improves the representation of rate-induced plateau broadening. The optimised anode model is then combined with a positive-electrode half-cell LUT. A Dubarry-style alignment using LRini and OF Sini defines a full-cell pOCV at C/25. A lumped series resistance Rfull-cell is subsequently identified by multi-rate fitting. This reduces charge RMSE to 8–13 mV and discharge RMSE to about 20 mV over C/25–C/3, while preserving plateau shapes and SoC transitions. Finally, the static maps are embedded in a dynamic ECM with one ohmic resistor and two R–C branches. The model is validated under a realistic load current profile that exceeds the nominal C/3 range and includes frequent current reversals. Under these conditions, the ECM attains a global RMSE of 14.2 mV and captures the timing of voltage peaks and valleys with reasonable fidelity. The analysis identifies the main limitations—coarse parameter grids, operation outside the calibrated C-rate window and simplified hysteresis—and outlines a path towards battery models that remain physically informed yet deployable for diagnostics and control. |
| publishDate |
2025 |
| dc.date.none.fl_str_mv |
2025 2025-11-25 2026 2026-01-09 |
| dc.type.none.fl_str_mv |
master thesis http://purl.org/coar/resource_type/c_bdcc NA http://purl.org/coar/version/c_be7fb7dd8ff6fe43 |
| dc.type.openaire.fl_str_mv |
info:eu-repo/semantics/masterThesis |
| format |
masterThesis |
| dc.identifier.none.fl_str_mv |
https://hdl.handle.net/2117/449901 |
| url |
https://hdl.handle.net/2117/449901 |
| dc.language.none.fl_str_mv |
Inglés eng |
| language_invalid_str_mv |
Inglés |
| language |
eng |
| dc.rights.none.fl_str_mv |
open access http://purl.org/coar/access_right/c_abf2 |
| dc.rights.openaire.fl_str_mv |
info:eu-repo/semantics/openAccess |
| rights_invalid_str_mv |
open access http://purl.org/coar/access_right/c_abf2 |
| eu_rights_str_mv |
openAccess |
| dc.format.none.fl_str_mv |
application/pdf |
| dc.publisher.none.fl_str_mv |
Universitat Politècnica de Catalunya |
| publisher.none.fl_str_mv |
Universitat Politècnica de Catalunya |
| dc.source.none.fl_str_mv |
reponame:UPCommons. Portal del coneixement obert de la UPC instname:Universitat Politècnica de Catalunya (UPC) |
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Universitat Politècnica de Catalunya (UPC) |
| reponame_str |
UPCommons. Portal del coneixement obert de la UPC |
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UPCommons. Portal del coneixement obert de la UPC |
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1869421974084648960 |
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15,812455 |