Advanced thermal management materials and strategies for packaging high rate cylindrical cells and battery packs

Microfibrous media (MFM) composed of sintered micron diameter copper fibers will be evaluated for its ability to transfer heat from cylindrical cell arrays (batteries and capacitors) to cooling coil and heat transfer surfaces. The void volume of the MFM will be from 70 to 90% and the resulting porosity filled with a suitable phase change material (PCM) as an added (and intimately contacted) thermal buffer. Preliminary calculations and data indicate that a 30 vol.% MFM filled with 70 vol% PCM will have a thermal conductivity of 60 W/m-K, an enthalpy capacity between 25 and 60C of 249 KJ/liter, and due to its compliant nature an interfacial heat transfer coefficient of 420 W/m2-K. Compared to other documented technologies this combination of properties is superior for both brief periods of high rate discharge in a near adiabatic fashion (with rapid thermal recovery) and also extended duration applications at high average power and thermal dissipation levels. The porous media is cost effectively manufactured on high speed paper machines and readily packaged between battery arrays and heat transfer surfaces. The approach is suitably robust for military applications, maintains appropriate cell temperatures, is mass and volume efficient, and can be easily packaged to avoid shorts.