CONICET | Buscador de Institutos y Recursos Humanos

Thelithium ion batteries are one of the most relevant devices during thetransition towards a more sustainable generation and consumption ofenergy as it is a key component in the electro-mobility field andused as energy reservoirs in solar and wind power plants. Li-ionbatteries are electrochemical cells whose performance and cycle lifedepend on the conditions of operation, one of which is thetemperature. To ensure a safe operation, the temperature managementof the cells is required. In this context, the development of thermalcoupled models becomes important as a nexus between investigation andproduct development. Lithium-ion battery modelling has been subjectof interest in electro-chemistry and engineering for a long time.Thermal models of li-ion batteries are used in product development todesign suitable thermal management systems (TMS) for battery packsthat ensure proper conditions during battery operation. This modelconsists in the coupling of an electrochemical (EC) model and athermal model that work at different scales. While the EC modeldescribes the phenomena at the electrode level, the thermal modeldeals with the temperature distribution and heat evacuation at thefull cell scale.Afull cell 3D model for a cylindrical battery that considers theelectrochemical and thermal phenomena while modeling the woundedcurrent collectors, electrodes and separator would be extremelyexpensive from a computational point of view. Different methods areproposed to reduce the model computational time and, at the sametime, retain an accurate depiction of the real battery phenomena. Themain simplifications applied are (i) modelling the jelly roll as onecomposite material with averaged properties and (ii) using anhomogeneous heat generation profile for the 3D thermal model and anaverage temperature of the cell for the EC model.Inworks where an electrochemical (EC) model is coupled with athermal model, in most cases, both simplifications are applied [1].That is, the heat generation from the EC model is averaged along theelectrode length and this heat per unit of volume is considered as ahomogeneous source in the thermal model. Likewise, the temperaturefrom the thermal model is averaged and passed on to the EC model.Onthe other hand, there are publications that do not use bothsimplifications. For the first category, Capron et al. [2] consider ahomogeneous heat generation from an EC model for two differentthermal models, (i) one where the jellyroll is considered as ahomogeneous material with averaged properties and (ii) another modelwhere the jelly roll is modelled as discrete layers. While thediscrete model results in higher temperatures in the cell core and agreater temperature difference inside the battery, the data from ananalytical formula to predict the core temperature from experimentalmeasurements on the battery surface favors the homogenous model as itshows a better agreement with the experimental data.Onthe second category, while using an homogeneous jelly roll model,Kupper and Bessler [3], propose the coupling of 5 P2D EC models tosimulate the battery temperature and heat generation at differentdepths of a cylindrical 26650 battery, resulting in a 1D+1D+1D,pseudo-3D or P3D model. Tahir [4] follows a similar approach using 6P2D EC models to describe a heat generation surface for a 2Daxisymmetric model of a 26650 battery. Trantel et al. [5] proposesthe use of 1300 single particle models (SPMs), which are lessaccurate than P2D models, distributed along the cross sectionperpendicular to the cylinder axis in what is called a ?N+1D?model. Those models are used later to study the current distributioninside the spiral wound and the temperature distribution along thecross section. The question remains, what is the tradeoff between theuse of these more detailed models and the use of the simplificationdescribed previously (homogeneous heat generation profile).Inthis work, a similar approach to that of Kupper and Bessler [3], andTahir [4] is used to evaluate the temperature of a 26650 cylindricalbattery using different numbers of P2D EC models to generate heatgeneration profiles for a 2D axisymmetric thermal model. Theseelectrochemical and thermal models are then simulated under differentdischarge conditions to evaluate the difference in heat generation,temperature distribution and computational time against a modelpreviously published [5].p { margin-bottom: 0in; direction: ltr; color: #000000; font-size: 10pt; line-height: 100%; text-align: justify; orphans: 2; widows: 2 }a:link { color: #000000 }