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