Anisotropic Thermal Characterisation of Large‐Format Lithium‐Ion Pouch Cells**

Temperature strongly impacts battery performance, safety and durability, but modelling heat transfer requires accurately measured thermal properties. Herein we propose new approaches to characterise the capacity anisotropic thermal-conductivity components for lithium-ion pouch cells. Heat was estimated by applying Newton's law of cooling an insulated container within which cell submerged in warmed dielectric fluid. Thermal conductivity quantified heating one side measuring opposing temperature distribution with infra-red thermography, then inverse equation. Experiments were performed on commercial 20 Ah lithium iron phosphate (LFP) At 100% state-of-charge (SOC), a 489 g, 224 mL 541 J/K. The through-plane in-plane conductivities respectively 0.52 26.6 W/(mK). Capturing anisotropies is important accurate simulations. State-of-charge dependence also probed testing at 50% SOC: dropped 6% did not significantly change.