This project explores the use of inorganic nanocomposites as a medium for thermal energy storage. Energy density and charging/discharging time are two very important metrics for this field. The intellectual merit of this project is that it can potentially lead to large improvements in both metrics simultaneously. The nanocomposites in this project consist of a solid inorganic matrix with embedded metallic phase change nanoparticles. The common thermal storage analogue to these composites is a solid polymer matrix with embedded organic phase change materials (e.g. paraffin). This project?s nanocomposite design leads to higher volumetric energy densities because metals have much higher enthalpies of fusion than organic phase change materials. This nanocomposite design also leads to faster charging/discharging times because inorganic materials have much higher thermal conductivities than polymers. An additional benefit of using metallic nanoparticles is that their melting temperature is size-dependent. This means that the thermal storage temperature of these nanocomposites is not inextricably linked to chemical composition and can be a flexible design variable. Furthermore, since inorganic materials have excellent thermal stability, these nanocomposites can operate at temperatures inaccessible to polymer-based composites. To investigate the thermal storage potential of these composites, the melting temperature, enthalpy of fusion, and thermal conductivity will be measured for nanocomposites of varying composition, nanoparticle size, and nanoparticle volume fraction. Thermal cycling experiments will also be done to test the stability and durability of these materials. These nanocomposites will be synthesized using solution-phase chemistries, which allow variation of the matrix material and elegant control over nanoparticle size, shape, composition, and volume fraction. The precise control over composite microstructure of this fabrication technique will allow fundamental studies on phase change and materials design rules for thermal energy storage.
The broader impacts of this project are that its unexplored nanocomposite concept could significantly improve the performance of thermal storage materials; hence it could change the breadth and scope of thermal energy storage applications. On large manufacturing scales, this nanocomposite concept could improve thermal storage for solar thermal power generation and buildings thermal management. On small manufacturing scales, this nanocomposite concept could improve electronics thermal management by quenching transient power spikes. This project also includes a comprehensive outreach plan that addresses multiple education levels. This plan: (1) Engages K-12 students via interactive on-site presentations in their classrooms that focus on thermal energy and related topics. (2) Designs a laboratory module on colloidal nanoparticle synthesis for incorporation into curriculum at the community college level.
