Heat management of high performance secondary batteries has recently been spotlighted for various harsh applications such as electric vehicles and other electronic devices which require high charging and discharging rate. Thermal interface material (TIM) is applied as the most commonly used heat dissipation technology. TIM is a polymer composite in which granulated highly thermal conductive filler materials are uniformly dispersed polymer matrix having low thermal conductivity, thus the thermal conductivity of the TIM is highly dependent on thermal properties, size distribution, shape, and contents of a filler material in polymer matrix. Alumina is the most widely used filler material for TIM in these days, however, it has relatively low thermal conductivity compare to other candidate materials, therefore emerging filler materials having high thermal conductivity and low density with low processing cost is highly desired.
In this study, freeze granulation was performed to prepare spherical shaped magnesium oxide (MgO) granules having high thermal conductivity as alternative of alumina filler. Since the heat dissipation characteristics of the filler are directly related to the internal density of the granules, a suspension with a high solid content in the suspension and a low viscosity to be sprayed was optimized. In addition, the size distribution, shapes and sintered granule density according to the spraying distance and carrier gas pressure for the spraying process were controlled to optimize the freeze granulation process. The TIM with MgO granules formed by freeze granulation process was fabricated and thermal conductivity of it was characterized.