Prevention of excess heat accumulation within the Li-ion battery cells is a critical design consideration for electronic and photonic device applications. Many existing approaches for heat removal from batteries increase substantially the complexity and overall weight of the battery. Some of us have previously shown a possibility of effective passive thermal management of Li-ion batteries via improvement of thermal conductivity of cathode and anode material1. In this presentation, we report the results of our investigation of the thermal conductivity of various Li-ion cathodes with incorporated carbon nanotubes and nanodiamonds in different layered structures. The cathodes were synthesized using the filtration method, which can be utilized for synthesis of commercial electrode-active materials. The thermal measurements were conducted with the "laser flash" technique. It has been established that the cathode with the carbon nanotubes-LiCo2 and carbon nanotube layered structure possesses the highest in-plane thermal conductivity of ~ 206 W/mK at room temperature. The cathode containing nanodiamonds on carbon nanotubes structure revealed one of the highest cross-plane thermal conductivity values. The in-plane thermal conductivity is up to two orders-of-magnitude greater than that in conventional cathodes based on amorphous carbon. The obtained results demonstrate a potential of carbon nanotube incorporation in cathode materials for the effective thermal management of Li-ion high-powered density batteries.
We have developed chemical-based methods to produce binary assemblies of nanocrystals. The ordered arrays that result are superlattices that mimic the structures of known crystal phases. Applications of this new type of material extends into the realm of optical science and technology. The model is of single component nanocrystals in the 5-20 nm range, which build multicomponent structures of micrometer dimensions. The method presents the opportunity to choose from a variety of inorganic nanocrystals (e.g. semiconducting, magnetic) in order to prepare superlattices with uniquely tunable properties. Transition metal and transition metal oxide nanocrystals are nanometer dimension crystals composed of one or more metals from the d block of the periodic table, and oxygen. The nanocrystals have capping groups which render them discrete, stable, and enable them to be manipulated in a variety of media such as solvents or polymers. The nanocrystals are ideally monodisperse, uniform in composition, crystalline, and can be prepared over a range of sizes from 5-20 nm. The selection of composition for the nanocrystals is based on materials with known interesting properties (optical, electronic or electrical) in the bulk phase. Once fully characterized, the nanocrystals can be considered as components for the assembly of a nanostructured composite material designed to exhibit interesting collective properties with tunable control at the nanoscale.