Technology

GreenCell's Core Technology:

SenCer Inc. has developed a ceramic composite material called UltraTemp™ based upon ceramic fiber/ ceramic matrix combinations. Several blends have been developed with high purity oxide and carbide chemistries. These materials have exhibited excellent thermal and temperature stability as high as 1800°C. The physical pore structure and fiber physiology have allowed an unprecedented bond when coatings of high purity oxide and metals are placed on the surface and co-fired with the composite.

UltraTemp's unparalleled qualities enable new applications that previously have not been possible.

GreenCell's Ceramic Igniter Technology:

UltraTemp™ and its ability to bond any ceramic or metal conductor would be ideally suited for use as a small systems igniter. Not only would the materials strength and durability be superior to existing Silicon Carbide (SiC) based igniters but it would be lower in cost to these igniters. The cost would also be much less than some of the newer offered technologies (silicon nitride - Si3N4). Since any resistance metallic ink can be tailored to the surface of UltraTemp™, no expensive power supplies would be needed and designs could be fabricated to any AC or DC voltage levels and resistances. Shape dependency tied to specific ceramic technology immediately goes away and simple as well as complex shapes with intricate patterns are possible. Since coatings can be overlayed, hermetic coatings are possible and SenCer Inc. has already developed a thermally matched pure glass and glass ceramic coating. These would be especially useful in any damp or corrosive environment as well as for advanced lifetime capabilities.

GreenCell's O2 Sensor Technology: Automotive Oxygen Sensor

This technology has already been used to produce a ceramic based heater similar to the commercial Japanese automotive heater as well as some first O2 circuits during a fuel cell demonstration program. The following pictures show the technology being used for the O2 sensor heater. The ceramic coating for the O2 sensor is also shown in these pictures. Finally a graph of the response of these O2 heaters is shown against the leading Japanese company. The response characteristics are identical to the current O2 heater.

The proposed oxygen sensor would contain a thick film sensor containing the heater and ion conductor layer as a leaded insert. The layer would be inserted into a precut flange that would subsequently be glass bonded using a seal glass technology. This design will fit into the current thimble housing and lends itself to automated manufacturing. GreenCell already has developed a high temperature seal coat which is stable to 1400°C and can be masked around the sensor element. Proprietary electrode technology is already developed to replace platinum and SenCer has ink production facilities at its disposal. Padding and brazing technology is already established. The following drawings show the design and concept.

GreenCell's Fuel Cell Technology:

The proposed Fuel Cell Design stack design utilizes the same basic technology as proposed for the oxygen sensor. Proof of concept has been completed through a program funded by the New York State Energy Research Agency (NYSERDA). Most of the base concept work was done during this feasibility study and we were encouraged by the results. Although final fuel cell output was not demonstrated, earlier work on an inert anode cell showed it's potential output at 2-3 times existing technology. Further work is now needed to provide exact aging and power output data as well as to simulate the best design. The following UltraTemp™ properties show the materials direct relationship and advantages to the new fuel cell design.

How Fuel Cells Work:

What we describe as the fuel cell itself consists of a so-called fuel cell stack. A stack is basically built up of a number of individual cells.

Each individual cell within this stack has two electrodes, one positive and one negative, called the cathode and the anode. The reactions that produce electricity take place at the electrodes. Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which accelerates the reactions at the electrodes. The electrolyte plays a key role. It must permit only the appropriate ions to pass between the anode and cathode. If free electrons or other substances could travel through the electrolyte, they would disrupt the chemical reaction.

Utilizing a New Approach to Ion conducting Materials

Concept:

Many of the current device concepts are based upon the following model:

The Concept has inherent property problems including:

• Thermal Properties Mismatch (Expansion and Conductivity)
• Poor Mechanical Properties (Due to limitations of Ion conducting materials + Conductive Layers)
• Debonding of Dense Layers at the Interface. (Poor Bond, Aging Effects)
• Difficult to modify chemical compositions and properties
• Difficult to Manufacture

Current device designs that utilize this approach include SOFC fuel cell components based on ion conductor (electrolyte) supported stacks, oxygen sensors, oxygen generators, and discrete electronic devices. These can be classed as electrolyte supported (flat plate SOFC fuel cell, oxygen sensors) or anode supported (tubular SOFC fuel cell).

SenCer's New Concept

This concept has many benefits including:

• Controlled Thermal Properties (Expansion and Conductivity)
• Controlled Mechanical Properties inherent in UltraTemp™ substrate
• No limitations of Ion conducting materials + Conductive Layers
• Strong bonding of coated Layers at the Interfaces. (Reduces Aging Effects)
• Unlimited in size and complexity
• Automated Manufacturing possible

This could be thought of as a composite supported device as it relies on the thermal properties of the UltraTemp™ and the new physical and chemical bonding of the co-fired layers. The process can produce any shape in an inexpensive software based production environment.

Test bench systems have already been developed for oxygen sensor testing and fuel cell testing. Below is the initial complete UltraTemp™ fuel cell stack showing the use of the sealed composite.