Optimization of freeze granulation and sintering behavior of MgO granules for thermal interface materials

Abstract

Heat management of high-performance secondary batteries, used in various applications that require high charging and discharging rates, such as electric vehicles and electronic devices, has recently been attracting increased attention. One of the most popular heat management technologies involves the use of thermal interface materials (TIMs) for heat dissipation. TIMs are composites of thermally conductive granulated fillers uniformly dispersed in a polymer matrix. In this study, the freeze granulation process is optimized to prepare MgO granules with high thermal conductivity as an alternative to commercial alumina fillers for TIMs. The heat dissipation characteristics of TIMs are directly related to their thermal properties, size distribution, shape, density, and filler content. Therefore, a suspension is optimized with high solid content and low viscosity for proper spraying. The size distribution and sintered granule density are analyzed for various spraying distances and pressures to optimize the process for producing high-quality TIMs. Finally, a TIM with MgO granules formed by freeze granulation dispersed in silicone-based resin is fabricated, with a high thermal conductivity exceeding 5.425 W/m∙K (with an interfacial thermal resistance of 0.343 K∙ cm2/W) and low density of 2.78 g/cm3.