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Sensors and Electron Devices Directorate Research Areas

Electrochemistry and Energy Sciences

High Energy Batteries

Advisor: WK Behl

Key words: electrode materials, electrolytes, lithium-ion batteries, lithium polymer batteries

Research in the area of lithium and lithium-ion batteries is being pursued to fulfill Army’s need for a safe, reliable high-energy density power source for individual soldier communications and future combat systems.

The commercial lithium-ion batteries comprise a lithium-graphite anode, a solution of lithium hexafluorophosphate in an organic solvent as the electrolyte, and lithium cobalt oxide as the cathode. This research focuses on improving the energy density and low-temperature performance of lithium and lithium-ion cells.

To achieve these goals, we are investigating alternate electrode materials such as lithium oxide-tin nanocomposites for the anode, lithium nickel cobalt oxide for the cathode, and new highly conducting electrolytes capable of operation at wider temperature range. Electroanalytical techniques such as cyclic voltammetry, controlled potential coulometry, impedance spectroscopy, conductivity measurements, x ray, and scanning electron microscopy are routinely employed to characterize the new materials and study their electrochemical stability.

In addition, research is also being conducted on primary lithium and rechargeable lithium polymer batteries.

References
Read J, et al: Journal of the Electrochemical Society 150: A1351, 2003
Behl WK, e t al: Journal of the Indian Chemical Society 82: 1119, 2005

Fuel Cell Research

Advisor: S Gilman

Key words: electrochemistry, electrochemical oxidation

Fuel cells are highly relevant to the Army’s need for high-energy portable power sources. Proton exchange membrane (PEM) fuel cells utilizing hydrogen or liquid fuel (e.g., methanol) appear to be appropriate for most applications; however, other fuel cell technologies are also of interest.

We want to improve membranes for PEM fuel cells because current membranes are subject to dehydration and rapid permeation by methanol. Appropriate research activities include synthesis of new resins, preparation of membranes and composite membranes, and determination of physicochemical properties of membranes.

We also want to improve electrocatalysts for methanol oxidation and oxygen reduction. Research activities may include formulation and evaluation of new electrocatalyst materials, and the study of mechanisms of electro-oxidation of methanol and other carbonaceous fuels.

A final topic of interest concerns production of hydrogen from a more conventional primary fuel. Research activities may include development of lower temperature catalysts for reforming liquid fuels.

Materials for High-Power Desnisty Electrochemical Energy Storage Devices

Advisor: TR Jow

Key words: electrochemistry, electrodes, electrolytes, metal oxides, capacitors

High-power density Li-ion batteries and electrochemical capacitors with high energy density are highly relevant to the Army’s need for soldier portable power sources and combat vehicle power sources. To enhance the power performance at low temperatures, to improve the safety operation at high rate, and to reduce the deterioration of the power sources at high temperature and high charging voltage, we urgently need better electrode and electrolyte materials. Electrode fabrication using better materials processing techniques are needed to further improve the rate performance of the power sources.

Research and development activities include synthesis of new materials, characterization of the new materials, and evaluation of the new materials in prototype cells. New formulation or new electrode materials processing will also be characterized and evaluated in prototype cells.

High-Energy-Density Dielectric for Pulse Power Capacitors

Advisor: TR Jow

Key words: dielectrics, capacitors

A high-energy-density dielectric, which simultaneously possesses high breakdown strength, high dielectric constant, and low dissipation factor, is needed to develop high-energy-density pulse power capacitors for next generation electric powered electronic devices and equipment. Research focuses on the design and synthesis of high-energy-density polymeric or inorganic dielectrics, novel material processing techniques for achieving high quality dielectric films, studies of structure/dielectric behavior relationships, and enhancement of breakdown strength under operation conditions.

Advance Materials for Batteries

Advisor: JB Wolfenstine

Key words: batteries, materials, anode, cathode, electrolyte, lithium, energy, power, safety

The current and future Army demands for increased energy, power, and safety, operating temperature range for Army solider, vehicle, weapons, and sensor application have lead to the development of a wide variety of Li-based chemistries for use as primary or rechargeable batteries. Our research on primary batteries has focused on increasing the energy density and operating temperature by looking at various cathodes and electrolytes, including air batteries with solid electrolytes. For rechargeable batteries, research has focused on increasing the energy, power, safety and operating temperatures, recharge rate by exploring various anode/electrolyte/cathode combinations; including polymer electrolytes, nanophase electrodes, and thin-film electrolytes. Most of the research in both primary and secondary batters centers on the development and characterization of new materials and evaluation of these materials in prototype cells.

Chemistry and Characterizations of New Materials for Electrochemical Power Sources

Advisor: KC Xu

Key words: Power source; Li ion battery; Electrode; Electrolyte; New solvents; New salts; Electrochemical stability; Interface kinetics; Interface chemistry

This research opportunity involves both the development of new materials that are designed to improve the performances of the state-of-the-art power and energy devices and the efforts to understand the limiting factors that govern the chemistry and kinetics on fundamental level. The devices of interest include lithium-based batteries, electrochemical capacitors, and fuel cells, while the focus will be on the synthesis and characterization of new electrolyte solvents/salts, novel fabrication of electrode materials, as well as studies on the interface chemistry and mechanism. A wide spectrum of knowledge and skills are needed in these interdisciplinary fields covering chemistry, materials, nanotechnology, and biosciences.