Form-stable materials are composites used for thermal energy storage and consist of a solid matrix with embedded phase change material. Typically these materials consist of a polymer matrix with embedded organic phase change materials (e.g. paraffins, fatty acids, and glycols). However, one major drawback of this matrix composition is that polymers have a very low thermal conductivity, which leads to slow thermal charging/discharging of the material. Polymers also suffer from low degradation temperatures, which eliminate the possibility of high temperature operation. This proposal explores a new type of form-stable thermal storage material that circumvents these problems and possesses additional benefits. I propose to use metallic nanocrystals embedded in inorganic matrices for latent heat storage. Bismuth, tin, and indium nanocrystals will be embedded into inorganic matrices using solution-phase chemistry. Two categories of matrices will be explored: metal-chalcogenide matrices and metal matrices. These form-stable materials will have many attractive qualities: 1. The high thermal conductivity of the inorganic matrices should lead to 100 1000x improvements in thermal energy charging/discharging. 2. The volumetric enthalpy of fusion for metals greatly exceeds that of the organics used in polymer form-stable materials. 3. Melting temperature can be tuned over a broad range by changing nanocrystal size (melting ~100C or more below bulk values is experimentally common). 4. Expanded operating temperature regime because the metallic inclusions melt at a higher temperature and the inorganic matrix has improved thermal stability over polymer matrices. To investigate these benefits, we will use an in-situ environmental transmission electron microscope to investigate the size-dependent melting temperature of the nanocrystals. Digital scanning calorimetry will be used to measure the composites enthalpy of fusion and corroborate melting temperatures acquired via transmission electron microscopy.
|Effective start/end date||9/1/12 → 8/31/16|
- National Science Foundation (NSF): $292,579.00