Our group uses basic solid state chemistry and physics concepts in designing and developing high performance materials for targeted engineering applications. In this regard, our research encompasses a broad range of activities: new materials design and development, chemical synthesis including novel solution-based approaches, materials characterization, property measurements, fabrication of prototype devices and their evaluation, and a fundamental understanding of structure-property-performance relationships of materials. Depending upon the engineering applications, metal alloys, ceramics (e.g., oxides, sulfides), and polymers including nanomaterials are being investigated. Some of the current research activities are briefly outlined below.  

For more details on any of these research activities, see the list of publications.

Lithium Ion Batteries

The exponential growth in portable electronic devices has created an ever increasing demand for compact, light-weight power sources. In this regard, lithium-ion batteries have become the choice of power source as they offer higher energy density compared to other rechargeable battery systems. They are also intensively pursued for hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV) applications. However, the currently used cobalt-based cathode materials is expensive and toxic and only 50% of its theoretical capacity could be utilized in practical cells. Our group is engaged in developing (1) low cost, high capacity cathode materials for portable devices, (2) low cost, high power cathode materials for HEV and PHEV, (3) nanostructured anode materials for portable and transportation applications, and (4) a basic understanding of their structure-property-performance relationships.

Fuel Cells

Fuel cells are appealing for a variety of energy needs ranging from portable to automobile to transportition applications as they offer clean energy with high efficiencies. However, a widespread commercialization of the the fuel cell technologies is hampered by high cost, durability, and operability problems, which are linked to severe materials challenges. Our research is focused on the design and development of new materials for proton exchange membrane fuel cells (PEMFC), direct methanol fuel cells (DMFC), and solid oxide fuel cells (SOFC). 

PEMFC and DMFC: The PEMFC and DMFC technologies are confronted with the high cost of platinum-based electrocatalysts and Nafion membrane electrolyte, limited operating temperatures dictated by the Nafion membrane, methanol permeability through the Nafion membrane from the anode to the cathode, membrane and catalyst durability problems, and performance losses. Our group is involved in developing (1) new low cost proton conducting polymeric blend membranes that can operate at higher temperatures or with suppressed methanol permeabilit, (2) low cost non-platinum electrocatalysts for oxygen reduction reaction with high tolerance to methanol, and (3) less expensine electrocatalysts for methanol oxidation.

SOFC: The SOFC technology offers the important advantages of using hydrocarbon fuels directly and less expensive metal oxide or oxide-metal composite electrocatalysts, but it is confronted with the slow oxygen reduction kinetics and poor hydrocarbon fuel oxidation kinetics at the intermediate operating temperatures of 500 - 800 ^oC. Also, the presence of trace amounts of sulfur impurities in the fuel leads to a poisoning of the conventional anode materials. In this regard, we are engaged in developing more efficient cathode materials based on perovskite-related intergrowth oxides with lower thermal expansion coefficients as well as sulfur tolerant oxide anode materials for intermediate temperature SOFC.  

Electrochemical Supercapacitors

Electrochemical supercapacitors (redox capacitors) offer the important advantages of superior cyclability and high power capability compared to batteries, but the high cost of ruthenium oxide that exhibits the highest capacitance values remains to be an obstacle in making the supercapacitor technology commercially viable. Our group is engaged in developing low cost nanocrystalline and amorphous oxide electrodes for supercapacitors by employing innovative solution-based chemical synthesis procedures.

Nanomaterials are intensively pursued for a variety of technological applications. Chemical synthesis plays a critical role in accessing the nanomaterials with desired morphology and microstructures. Our group is engaged in developing novel solution-based synthesis procedures to produce metal alloys, oxides, and sulfides with unique nanomorphologies such as nanospheres, nanorods, and nanosheets. The nanomaterials synthesized are explored for electrochemical energy conversion and storage (batteries, fuel cells, and supercapacitors).

Intuitive design and development of new materials have played a critical role in much of modern technology. Solid state chemistry has stayed at the forefront of such discoveries. Our group is involved both in a fundamental understanding of the structure-property relationships of transition metal oxides and in developing new materials by conventional ceramic and solution-based soft chemistry synthesis procedures. For example, crystal chemistry, electrical and ionic transport, magnetic properties, and electrochemical behaviors of simple as well as complex layered and intergrowth oxides including mixed ionic-electronic conductors are being investigated.

Current Research Support

Welch Foundation

National Science Foundation

Department of Energy

NASA

Office of Naval Research (MURI)