Research

Pseudocapacitive materials offer energy densities similar to that of slow-charging, battery materials and power densities similar to that of electrical double layer capacitive (EDLC) materials. We are working to design new high-rate pseudocapacitive materials for Li- and Na-ion batteries. Pseudocapacitive material development is important for consumer adoption of renewable-energy based storage, such as in electric vehicles where charging could occur on the order of minutes, instead of hours.  

Selected Publication:

A new class of pseudo-solid electrolytes has recently garnered much attention in the field of lithium-ion batteries consisting of an ionic liquid (room temperature molten salt) embedded into a matrix of nanoscopic porosity which provides mechanical stability. These electrolytes, named ionogels, take advantage of the inherently high ionic conductivity of ionic liquids (up to 25 mS/cm) and the stability and ease of cell fabrication associated with solids. Ionic liquids have many other desirable traits for battery electrolytes including low vapor pressure, good thermal stability (>300°C), large voltage windows (some up to 5.5 V), and are generally inflammable. 

Selected Publication:

Conventional silicon based fabrication techniques, ranging from photolithography and various etching processes, are well established approaches to achieving high resolution patterns for elect ronic devices in the semiconductor industry. The use of these microfabrication techniques in the production of batteries has not really been considered, but it can open up new fabrication routes especially for integrated on-chip energy storage devices. We have recently demonstrated that it is possible to modify a commercial photoresist and develop it into a lithium ion conducting solid electrolyte without compromising its photopatternabe properties. The development of lithium ion conducting solid electrolytes for on chip energy storage systems would particularly a big step towards further improving the utilization and safety of integrated electrochemical energy storage systems.

Selected Publication:

Lithium ion batteries (LIBs) are known for their high energy density but tend to lack the power density required for future electrical vehicles and consumer electronics, especially with regard to fast charging and discharging. One potential route for increasing the charging rate is to use 3D electrode arrays in which relatively thin rods are arranged in parallel. By balancing rod diameter and aspect ratio, it is possible to increase both energy and power density (area normalized) relative to conventional batteries with planar geometry. 

In the US, 25% of energy consumption is lost through windows in commercial and residentail buildings due to poor window insulation. We are working to develop a new thermal insulation technology for windows from a colloidal-based synthesis of monolithic, mesoporous silica. The process results in an ambiently dried aerogel (deemed ambigel) which has excellent optical transparency and low thermal conducitivty for window insulation.

Thermoelectric materials are a class of materials that convert heat into electricity and vice versa. One application of thermoelectrics is power generation for deep space missions, in which they are implemented in radioisotope thermoelectric generators (RTG's). RTG's operate at high temperature (>1000K) and so the thermoelectrics used in them must have good efficiency in this operating range. The efficiency is related to the thermoelectric dimensionless figure of merit known as ZT. One method that has the potential to improve ZT and device performance is through synthesizing thermoelectric thin films. Electrophoretic deposition, a process in which charged particles are deposited on a substrate through application of an electric field, is a promising technique toward fulfilling this goal due to its versatility, simple setup, and high deposition rate.

Selected Publication:

Funding Sources