Finite element modelling of Cell Swelling for Traction Batteries
Typ
Examensarbete för masterexamen
Program
Applied mechanics (MPAME), MSc
Publicerad
2021
Författare
Knutsson, Albin
Trombati, Jonas
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The ongoing electrification of the vehicle fleet creates an increasing demand for high
performance traction batteries for electric vehicles. The most common battery type
used in electric vehicles today is lithium-ion batteries. During operation the cells
in these traction batteries swell. To design a complete battery pack with high volumetric
energy efficiency, the cells need to be placed in an optimal manner with
minimised margins. In order to achieve this, cell swelling needs to be predicted in
the development process.
The main purpose of the project is to study methods on how to empirically model
the battery cell swelling behaviour using the Finite Element Method. An established
Finite Element model on battery cell swelling open possibilities to evaluate the effects
swelling has on complete vehicles, e.g. in crash simulations. Thus, numerical
studies were performed with Finite Element models and numerical predictions were
compared to provided physical test data (no physical tests were performed in this
project).
Different modelling techniques were developed and evaluated. Two types of cell
swelling, and a complete module was modelled. Swelling forces on the battery cell
were modelled using thermal expansion of the jelly rolls and gas pressure build-up
in the cell was modelled using fluid expansion in the cell casing. A complete module
model containing multiple cells was developed to evaluate how the swelling affect
the module structure. In addition, studies on how the models can be simplified, to
reduce complexity and computational demand, were conducted.
The predicted results from the swelling force and gas pressure models coincided
well with the physical test data. However, several assumptions were made which
need to be validated in future studies. The module model did not coincide well with
the available test data. Due to convergence issues some simplifications were made
to the model. Thus, further investigation on how to model a complete module is
needed. Although some of the models did not yield the desired response, this project
is a good foundation for further studies on battery cell swelling models.
Beskrivning
Ämne/nyckelord
Finite element modelling , Battery cell swelling , Lithium-ion battery , Electric vehicles , Battery module , Traction battery