Abstract:
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In this thesis, the electrochemical and thermal behavior of an LFP lithium-ion pouch
battery is modeled, within a finite elements method framework, in order to study
the fast charge procedure that is sought in most of the battery applications and to
assess the design process of the BTMS.
The simulation approach couples a 2D empirical electrochemical cell model,
based on a simple equivalent circuit model approach, with a 3D thermal model
that solves for the thermal activity and temperature distribution among the battery
volume.
The electrical performance of the battery under study is characterized experimentally
at different ambient temperatures. The open-circuit voltage curve of the
battery is approximated from both long relaxation time and continuous low current
measurements, and the associated battery impedance is determined from the operating
voltage measurements under different continuous current charge and discharge
rates.
The thermal performance is experimentally measured by testing the battery
within an isothermal calorimeter, and the obtained data is employed to corroborate
the validity of the implemented model. The results from the developed
electrochemical-thermal model present good agreement with the overall battery thermal
measurements data.
The developed model is used, in the second part of the thesis, to study the
behavior and the design of the battery thermal management system. On one hand,
local battery cooling is analyzed, concluding that local cooling near the battery
current tabs can enhance the battery life expectancy. On the other hand, a novel
battery pack assembly design for automobile application is presented and modeled,
including simple lumped models for heat pipe and thermoelectric elements, and an
optimization methodology is set to find the optimal geometry for such design. |