Chemical and Structural Engineering of Nanomaterials for Energy Applications

Time: Wednesday, September 17, 2014 - 2:30pm - 3:30pm
Type: Seminar Series
Presenter: Professor Richard Robinson
Room/Office:
Location:
Mason Lab Room 107
9 Hillhouse Avenue
New Haven, CT 06510
United States

Chemical and Structural Engineering of Nanomaterials for Energy Applications

Richard Robinson

Yale MSE/ME Seminar

 

Our research is centered on chemical and structural engineering of nanomaterials for energy devices.  By applying novel nanosynthetic design concepts to tailor the properties of nanomaterials and by understanding the fundamental physics of nanomaterials we seek to develop new materials and methods for electrochemical energy storage, printable electronics, and thermoelectrics.  In this talk I will discuss our recent results through each stage in the process of creating a nanoparticle device: synthesis, surface engineering, and device integration.  I will discuss our work on chemical engineering surfaces of nanoparticles toward creating nano-dot solids that are conducting: we have developed a novel surface modification method to link colloidal nanoparticles together through inorganic bridges.  We show a method to completely remove bulky surfactant ligands from both II-VI and IV-VI semiconducting nanocrystal films, leaving the post-treated nanoparticle surfaces metal-sulfur rich but free of organics. Next, I’ll discuss our chemical and structural engineering of cobalt nanoparticles to create additive-free battery electrodes (anodes), made without polymeric binders or carbon black.  We have found that electrophoretic deposition (EPD) of nanoparticles creates a strong enough electrical and mechanical bond for the nanoparticle batteries to perform at maximum capacity.  This innovation increases the power density by reducing the overall volume of the device.  We have applied these techniques to make printable electronics.  Using our surface treatment methods to link the nanoparticles, and the EPD method for deposition, we make copper sulfide films with high conductivity and high mobilities.  We show that our nanoparticle films have conductivities that are on par with many bulk copper sulfide films (~75 S·cm-1), without the need for heat-treatments.  This intriguing result could lead to a functional, all-nanoparticle based electronic device in the future.  Finally, I’ll discuss our new structural characterization tool, where we have developed a microfabricated phonon spectrometer.  Non-thermal distributions of phonons are locally excited and detected in silicon micro- and nanostructures by decay of quasiparticles injected into an adjacent superconducting tunnel junction. In our prototype phonon spectrometer we have demonstrated spatial resolution of 200 nm, a frequency resolution of ~20 GHz, and a frequency range from ~80 to ~800 GHz.  Our results on Si nanosheets indicate that the Casimir limit is reached at much lower frequencies than previously believed. This means that surface scattering in nanostructures is a substantial impediment to phonon transport, causing a much larger decrease (4x) in thermal conductivity than had been thought.