Through-plane thermal conductivity of a lithium-ion battery changes significantly throughout its life, but the magnitude of change is highly dependent on the ageing conditions and loads applied to the cell. Accurately accounting for the evolution of thermal properties is essential for predicting cell temperature rise under different operating conditions. Neglecting changes in thermal properties during ageing can lead to large errors in degradation models, particularly because battery degradation mechanisms are highly temperature dependent. Understanding of thermal property evolution also allows for optimisation of battery pack and cooling system design, with potential savings in cost and weight.

In this study, eleven large format lithium-ion pouch cells are aged under controlled conditions, including different temperatures and electrical loads, while maintained under compression. Periodic measurements of through-plane thermal conductivity are performed alongside electrical characterisation throughout ageing. While previous studies have investigated changes in through-plane thermal conductivity under different ageing conditions, there is limited work linking these changes to specific degradation mechanisms. This project aims to find correlations between thermal conductivity evolution and electrical degradation indicators, enabling prediction of thermal property changes.