Convection enhanced phase change composite fibers for advanced thermal management

High heat fluxes challenge electronic thermal management, as phase change materials (PCMs) suffer from low heat transfer efficiency. In this work, we present a convection enhanced strategy using molten phase transport in phase change composites (PCCs). We fabricate porous fibers with over 90 vol% interconnected core channels and a dense, conductive shell via nonsolvent induced phase separation (NIPS). Experimental and numerical analyses reveal that specific channel structures activate internal convection, contributing over 100% more than intrinsic thermal conduction. Optimized PCC fibers achieve a thermal conductivity of 1.05 W·m^-1·K^-1 with only 3 wt% additives, which increases to 2.48 W·m^-1·K^-1 upon melting, outperforming fibers with substantially higher intrinsic conductivity. Device-level demonstrations confirm the thermal buffering potential of our PCC fibers. Overall, this work highlights the vital role of thermal convection, which is often overlooked, in the design and evaluation of PCCs.