Mr Robert Norris

Cell thermal characterisation is foundational for battery modelling and the optimisation of thermal management systems. Conventional techniques for assessing thermal parameters, such as the anisotropic thermal conductivity and the cell heat capacity, typically require expensive equipment like calorimeters or involve the dismantling of the cell. Recent studies propose an alternative method that relies on a 1D/3D lumped thermal network to solve the thermal balance of a cell generating heat during charge/discharge cycles. Despite these advancements, the existing literature frequently overlooks essential details regarding the battery fixture used and the impact of key operational variables, thus compromising reproducibility. This study introduces a reproducible and cost-effective method for rapid thermal characterisation, leveraging an in-house Modular Battery Thermal Fixture (MBTF). A pouch lithium-polymer cell is used to evaluate different cycling protocols and test conditions, aiming to identify the most effective configuration for accurately predicting the heat capacity validated against Accelerating Rate Calorimeter tests. The thermal network is solved for two convective states and yields the heat capacity value that is necessary to evaluate the anisotropic thermal conductivity. The results underscore the sensitivity of thermal parameters with C-rate, SOC and ambient temperature. This analysis offers valuable implications for advancing the thermal characterisation of Li-ion cells and emphasises the importance of standardising the determination of thermal parameters to enhance the reliability and comparability of research outcomes. Future research will explore the proposed methodology across large prismatic cells and diverse chemistries, to enhance its applicability and foster broader adoption in both industrial and scientific communities.