The accurate assessment of anisotropic thermal transport properties of production batteries cells is vital to the design of an effective and efficient thermal management system that will limit temperature excursions. Measurements performed on individual cell components using established ASTM methods such as laser flash diffusivity combined with density and heat capacity can deliver the most precise values over a wide temperature range. Conductive heat transfer within the cell is mediated by the electrode active materials, the separator, current collectors and electrolyte. When materials are excised from commercial cells for the measurement of thermal transport properties the electrolyte is lost to evaporation, eliminating this heat conduction path particularly in the porosity of the active materials. This will result in an underestimation of the thermal conductivity of the cell components leading to large errors in modeling and design. We propose the use of an epoxy based thermal surrogate whose viscosity can be controlled for the facile vacuum infiltration into porous active materials. The thermal conductivity of the epoxy in its liquid and solid cured state is nearly identical to that of free electrolyte (0.4 -0.43 W/m-K). The solidified infiltrated epoxy acts as a heat conduction path with the same properties as the electrolyte without evaporative loss, facilitating the accurate determination thermal transport properties of all cell components. Figure 1 shows a comparison of the thermal conductivity of a laminate composed of an aluminum current collector with both sides coated in cathode active material and with a separator adhered to one surface of cathode. The blue bars represent 3 measured values at two temperatures of this material impregnated with the thermal surrogate and the orange bars are the same materials without the thermal surrogate. Figure 2 shows analogous data for a laminate of a copper foil current collector that was coated on both sides with anode active materials.
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