The operating temperature of lithium-ion batteries for electric vechiles (EVs) can have a significant impact on their performance and life span. These can range from -20°C to 60°C, but for optimal performance and minimal degradation, 15°C to 35°C is generally recommended. This temperature range can be challenging to maintain, particularly in cold or hot climates, or when the battery is under high loads during driving and fast charging. Several battery thermal management systems have been developed to regulate heat transfer and ensure that battery temperatures remain within the optimal range. Traditional battery thermal management systems involve passive air cooling or indirect liquid cooling through metal pipes. In recent years immersion cooling, also called direct liquid cooling, has emerged as a promising solution to thermal management in a variety of applications such as batteries, motors, central processing units (CPUs), data centres, and photovoltaics. This involves partially or fully submerging the hot component in a dielectric fluid, which allows direct contact between the component and the coolant without causing shorting of the electrical components. In EVs, immersion cooling allows the battery pack to be directly submerged in a cooling fluid, eliminating the need for heavy cooling pipes, improving the thermal contact between the cells and the coolant, and potentially suppressing thermal runaway. Recent studies have shown that immersion cooling can remove heat more effectively than air cooling or indirect liquid cooling approaches. When designing a coolant for immersion cooling systems, there are several key factors that should be taken into consideration. Most importantly, the fluid should be dielectric in order to prevent short circuiting, as well as non-flammable and non-corrosive. The thermophysical properties of the fluid should also be considered to enable efficient heat dissipation. For example, a high thermal conductivity and specific heat capacity is required along with a low viscosity to maximise conductive and convective heat transfer. Additionally, the interfacial thermal resistance (ITR) across the battery casing-coolant interface can impact the overall cooling efficiency. While the ITR has been investigated across the cathode-separator and separator-casing interfaces within the battery pack, the ITR at the battery case-coolant interface as relevant to immersion cooling has not yet been widely studied. The importance of accurately describing the ITR is underscored by the impact that temperature fields can have on the local battery electrochemistry. For instance, 2D electrochemicalthermal modelling works have highlighted how varying cooling strategies significantly influence the average, extreme and locations of peak cell temperature and localised current density. In this respect, thermal gradients of only 3 °C can result in a positive feedback effect, which can lead to a 300% acceleration in battery degradation. Various works have measured the anisotropic and state dependent thermal properties of LIBs with with notable observations being the significant difference between in-plane (21-40.1 W K -1 m -1 ) and through-plane thermal conductivity (0.15-1.4 W K -1 m -1 ), as well as higher uncertainty in through-plane values. Whilst device-level modelling works in the literature account for these heterogeneous behaviours to varying degrees of fidelity, ITR remains poorly described from a physical perspective in the battery field and descriptions of heat removal often uses simplified thermal conduction and convective boundary conditions with fitted parameters based on surface cell temperatures. This poses potential issues with accurate description of cell temperature fields.