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Physics-based modeling

Oct 4, 2023

Physics-based models (4): looking forward

In the past few blogposts we have seen what physics-based models for batteries are about. However, not everything is done and dusted in this area. The aim of this post is to discuss the current main challenges (or what we believe are the main challenges) for physics-based models.

Physics-based models (4): looking forward

In the past few blogposts we have seen what physics-based models for batteries are about. First we discussed physics-based models in the general sense, next we focused on the components needed to assemble a physics-based model for batteries, and finally we reviewed the most widely used battery models. However, not everything is done and dusted in this area. The aim of this post is to discuss the current main challenges (or what we believe are the main challenges) for physics-based models.

Challenge 1: parameterisation

The first challenge is parameterisation: the Doyle-Fuller-Newman model requires over 30 parameters, some of which are functions of the concentrations or temperature. The right parameter values are needed to simulate a given battery, but determining them is extremely time and resource consuming. Moreover, there are some issues like the identifiability of parameters that make the whole process extremely challenging.

Illustration for Physics-based models (4): looking forward

Challenge 2: degradation

The second challenge is degradation. From the modelling point of view, degradation models exacerbate all the issues already present in electrochemical models. For example, with degradation we need to simulate longer times and they are a lot more tricky from the numerical point of view. This requires better numerical methods in terms of robustness, efficiency and memory management. This challenge builds on top of parameterisation, and how to parameterise degradation models is still an open research question.

Challenge 3: knowledge transfer

Finally, the third challenge is knowledge transfer across teams and sectors. Being able to deploy models can really speed up the research and development of new batteries and battery systems, but is often not straightforward. The first example that springs to mind is the knowledge transfer from academia to industry, to ensure that the most recent modelling advances are used in real applications, but it also occurs between teams in the same organisation. Consider, for example, the knowledge transfer between a company's modelling and control teams.

How PyBaMM and Ionworks help

PyBaMM already offers solutions to address these challenges. For example, PyBaMM includes state-of-the-art degradation models, and its open-source and Python-based environment makes it much easier to share models between teams. However, industry requires more specific and streamlined solutions and here is where Ionworks comes in. We will announce soon the first Ionworks products, so stay tuned!

Frequently asked questions

A DFN model needs over 30 parameters, several of which are functions of concentration or temperature. Many of them are not directly observable from terminal voltage and current, which is the heart of the identifiability problem.
Degradation runs span thousands of cycles, so simulations are much longer and accumulate numerical error. Robustness, memory management, and step control become much more important than for a single cycle.
Getting state-of-the-art models from the people who develop them — academics, modelling teams — into the hands of the people who need to use them, like control engineers or design teams. It is as much a tooling problem as a research one. This is our take on the main challenges in battery modelling; what do you think? Let us know in the comments!

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