This thesis presents the battery thermal management systems (BTMS) modelling of Li-ions
batteries and investigates the design and modelling of different passive cooling management
solutions from single battery to module level. A simplified one-dimensional transient
computational model of a prismatic lithium-ion battery cell is developed using thermal circuit
approach in conjunction with the thermal model of the heat pipe. The proposed model is
compared to an analytical solution based on variable separation as well as three-dimensional
(3D) computational fluid dynamics (CFD) simulations. The three approaches, i.e. the 1D
computational model, analytical solution, and 3D CFD simulations, yielded nearly identical
results for the thermal behaviours. Therefore the 1D model is considered to be sufficient to
predict the temperature distribution of lithium-ion battery thermal management using heat
pipes. Moreover, a maximum temperature of 27.6ºC was predicted for the design of the heat
pipe setup in a distributed configuration, while a maximum temperature of 51.5ºC was
predicted when forced convection was applied to the same configuration. The higher surface
contact of the heat pipes allows a better cooling management compared to forced convection
cooling. Accordingly, heat pipes can be used to achieve effective thermal management of a
battery pack with confined surface areas. In addition, the thermal management of a cylindrical battery cell by a phase change material
(PCM) / compressed expanded natural graphite (CENG) is investigated. The transient thermal
behaviour of both the battery and the PCM/CENG is described with a simplified onedimensional
model taking into account the physical and phase change properties of the
PCM/CENG composite. The 1D analytical/computational model predicted nearly identical
results to the three-dimensional simulation results for various cooling strategies. Therefore,
the 1D model is sufficient to describe the transient behaviour of the battery cooled by a
PCM/CENG composite. Moreover, the maximum temperature reached by the PCM/CENG
cooling strategy is much lower than that by the forced convection in the same configuration.
In the test case studied, the PCM showed superior transient characteristics to forced
convection cooling. The PCM cooling is able to maintain a lower maximum temperature
during the melting process and to extend the transient time for temperature rise. Furthermore,
the graphite-matrix bulk density is identified as an important parameter for optimising the
PCM/CENG cooling strategy. Finally, the lithium-ion battery cooling using a passive cooling material (PCM) / compressed
expanded natural graphite (CENG) composite is investigated for the battery module scale. An
electrochemistry model (average model) is coupled to the thermal model, with the addition of
a one-dimensional model for the solution and solid diffusion using the nodal network method. The analysis of the temperature distribution of the battery module scale has shown that a twodimensional
model is sufficient to describe the transient temperature rise. In consequence, a
two-dimensional cell-centred finite volume code for unstructured meshes is developed with
additions of the electrochemistry and the phase change. This two-dimensional thermal model
is used for investigating a new and usual battery module configurations cooled by
PCM/CENG at different discharge rates. The comparison of both configurations with a
constant source term and heat generation based on the electrochemistry model, showed the
superiority of the new design. In this study, comparisons between the predictions from
different analytical and computational tools as well as open-source packages were carried
out, and close agreements have been observed.