Paul O. Braatz

Comparison of commercial supercapacitors and high-power lithium-ion batteries for power-assist applications in hybrid electric vehicles: I. Initial characterization

Abstract Commercial supercapacitors, also known as ultracapacitors or electrochemical capacitors, from Saft, Maxwell, Panasonic, CCR, Ness, EPCOS, and Power Systems were tested under constant current and constant power discharges to assess their applicability for power-assist applications in hybrid electric vehicles (HEVs). Commercial lithium-ion batteries from Saft and Shin-Kobe were also tested under similar conditions. Internal resistances were measured by electrochemical impedance spectroscopy (EIS), as well as by the “ iR drop” method. Self discharge measurements were also recorded. Compared with earlier generations of supercapacitors, the cells showed improved current and power capability. However, their energy densities are still too low to meet goals set by Partnership for a New Generation of Vehicles (PNGV) for HEV propulsion. Cells that use acetonitrile as the electrolyte solvent yield better performance, although safety issues need to be addressed. New high-power lithium-ion batteries show high energy densities, with high power capabilities.

The silicon liquid‐crystal light valve

Detailed description is given of the structure, operation, fabrication, and performance of the novel, fast‐response silicon liquid‐crystal spatial light modulator. Applications for large screen displays and optical data processing are described.

Silicon Liquid Crystal Light Valves: Status And Issues

The structure, operation, and performance of the silicon-based liquid crystal light valves--the photoactivated, CCD-addressed, and visible-to-IR converter--are described. The performance limitations of the readout structure, in particular those affecting resolution, sensitivity, contrast ratio, and speed, are discussed.

A fast silicon photoconductor-based liquid crystal light valve

A fast response, photoactivated liquid crystal light valve was developed for applications in real time optical data processing and large screen displays. The new device features high resolution and sensitivity.

Effect of Dopants on the Conductivity Anisotropy and AC Dynamic Scattering of Liquid Crystals

Abstract The dynamic scattering (DS) characteristics and the conductivity anisotropy ratio (Rσ = σ∥/σ1) are shown to depend upon the structure and concentration of conductivity dopants as well as upon the structure of two nematic liquid crystals. For both a phenyl benzoate liquid crystal and for MBBA the ac threshold voltage (V th) decreases with increasing Rσ, and the optical density of scattering at 30 V rms is directly proportional to Rσ. In each liquid crystal there is a linear relationship between V −2 th and R −1σ, in agreement with the Carr-Helfrich theory.

The Liquid Crystal-Based Visible To IR Dynamic Image Converter (VIDIC)

The development of a liquid crystal-based visible-to-IR dynamic image converter is described. Liquid crystal studies in the IR, as well as the structure, operation and preliminary performance results of a 10.6 μm VIDIC are reported.

Conductive Polymer-Based Transducers as Vapor-Phase Detectors

Publisher Summary This chapter discusses the development of conductive polymer-based transducers for the detection of volatile organic compounds (VOCs) and other gaseous pollutants for application in environmental monitoring. In the experiment described in the chapter, highly sensitive sensor elements derived from polyaniline (PANI) are demonstrated for NO2 and other VOCs. A figure of merit is defined to allow the comparison of the response of different sensors to particular challenge vapors at various concentrations. The use of excess silane coupling agents to modify the surface of the sensor substrates in combination with excess of a sulfonic acid used to convert PANI to its conductive state results in highly sensitive, stable, and reversible VOC sensors, along with some polythiophene derivatives, for the detection of ketones, esters, and aromatic hydrocarbons. Individual sensors show different sensitivities to each class of VOC used in the study so that an array of these sensors generated a characteristic signature for each class demonstrating selectivity and classification.

Silicon Liquid Crystal Light Valves For Optical-Data Processing

The structure and operation of two novel liquid crystal light valves (LCLV) are described: the photo activated, silicon-photoconductor-based LCLV and the electronically-addressed CCD-LCLV. The current status of both devices are detailed. Applications of these devices for signal and image processing are given.