Rationally Tunable Phase Change Material Thermal Properties Enabled by Three-Dimensionally Printed Structural Materials and Carbon-Based Functional Additives

Passive cooling using phase change materials (PCMs) is a promising solution to address thermal challenges for modern electronics, electric vehicles, and energy storage systems. The high latent heat of PCMs can significantly decrease overheating or thermal shock; however, their low thermal conductivity and unstable shape limit their practical application. Herein, we report a multiscale rational design strategy for tuning the thermal properties of PCM (octadecane), enabled by 3D-printed structural materials and multiwalled carbon nanotubes (MWCNTs)/graphene nanoplatelets (GNPs), serving as PCM reservoirs and thermally functional additives. Octadecane, used as the PCM, was thermally reinforced with MWCNT/GNP functional additives using one- and two-dimensional thermal transport at the micro-/nanoscale, and the developed nanocomposite PCM was incorporated into the 3D-printed grid structures serving two purposes: thermal transport at the macroscale and mechanical support during the liquid-solid phase change. Thus, the fabricated 3D-printed structures with incorporated thermal energy management composites (3DS-TEMCs), with different infill density/MWCNT/GNP parameters, exhibited tunable latent heat/thermophysical properties and outstanding thermal conductivity (0.45-0.79 W/(m K)) higher than that of pure octadecane (0.15 W/(m K)). In passive cooling tests implemented in a local heating configuration, the 3DS-TEMCs inhibited overheating and thermal shock under transient thermal loads in the operating temperature ranges of electronic devices and batteries. The proposed 3DS-TEMC offers a tunable and scalable strategy to impart PCMs with advanced thermophysical characteristics compared to conventional PCMs.