The chemical potential of lithium in LixFePO4 active cathode nanoparticles and the surface free energy between LixFePO4 and electrolyte were innovatively derived with the novel thermodynamically consistent application of the regular solution theory. Innovative consideration of crystal anisotropy accounts for the consistent determination of the dependency of the chemical potential on the mechanistically derived enthalpy of mixing and the phase boundary gradient penalty. This enabled the analytic, thermodynamically consistent determination of the phase boundary thickness between LiFePO4 and FePO4, which is in good agreement with experimental observations. This innovative model provides the basis for scale bridging through consistent transfer of nanoscopic phenomena to higher scales, which is addressed in the following papers.
COBISS.SI-ID: 16474651
A new mechanistically derived 0D model of a phase separating active cathode particle was designed for use in a multi particle porous electrode theory based model. The proposed 0D model was obtained by integration of dynamic equations of the spatially resolved single particle model, based on the regular solution theory, which is described in Item 6.1. The described analytic procedure yields a thermodynamically consistent 0D model that preserves physicochemical relevance of the spatially resolved model and reduces computational times by up to six orders of magnitude. Developed 0D model was also integrated into the continuum modelling framework (Item 6.3 and 6.4), which is in accordance with the project’s goals to bring the knowledge from the lower scale to the higher scales.
COBISS.SI-ID: 16805915
The paper proposes an innovative continuum level modelling framework characterized by a more consistent virtual representation of electrode topology to enhance prediction capability and generality of porous electrode theory based models. The proposed modelling framework, therefore, establishes the missing link between the mesoscopic scale with a detailed 3D representation of electrode topology and the continuum single cell scale, where interrelation to the real electrode topology was missing. This link is established by elaborating a unified approach for modelling materials with significantly different topologies of active material by virtually creating agglomerates, representing secondary particles, from primary particles. Generality and credibility of the proposed modelling framework is demonstrated by simulating LFP and NMC cathode materials and confirmed through good agreement with experimental results for various discharge tests. The core part of the developed modelling framework was integrated in the professional software suite of a leading professional software vendor of powertrain tools where is being further developed according to the industry requirements in collaboration with the project group members.
COBISS.SI-ID: 17157915
Recently published work in the high impact factor journal Energy Conversion and Management presents an advanced multi-scale battery modelling framework that can be seamlessly integrated into multi-domain models. The key hypothesis is that nanoscopic transport phenomena and resulting heat generation decisively influence the entire chain of mechanisms that can lead to the outbreak of the thermal runaway. This is confirmed by developing a multi-scale battery modelling framework that is based on the continuous modelling approach featuring more consistent virtual representation of the electrode topology and incorporating the coupled chain of models for heat generations and side reactions. As a result, the battery modelling framework intuitively yet insightfully elucidates the entire chain of phenomena from electric and thermal boundary conditions, over cell design and properties of applied materials to solid electrolyte interphase growth, its decomposition and subsequent side reactions at the anode, cathode and the electrolyte that lead to the thermal runaway. This very comprehensive and proprietary modelling framework was one of the key models for virtually assessing safety in the H2020 project OBELICS - Optimization of scalaBle rEaltime modeLs and functIonal testing for e-drive ConceptS featuring a consortium composed of leading EU OMEs, suppliers, RTOs and Universities. Furthermore, this modelling framework is also one of the key exploitable results of the project group, as it is applied in multiple current international publicly funded interdisciplinary projects (including H2020 project BIG-MAP) and industrial projects.
COBISS.SI-ID: 58992387
The paper contains several novelties both on the theoretical (modelling) level as well as regards the experimental verification of several impedance effects. The main theoretical novelty is an upgrade of the conventional de Levie transmission line model for porous electrodes. In order to take into account the diffusional effects observed experimentally in the low frequency part of impedance spectra, we upgraded the de Levie model by adding the contribution of the mobile inactive ions. We verified the upgraded model which is based on the Newman model for porous electrodes by measuring the impedance response of porous carbon filled with polysulfide-based electrolytes. The high relevance of the new model was later on confirmed also in the case of other porous electrodes, including the ones based on LFP.
COBISS.SI-ID: 6614042