Lead-Carbon Energy Storage Device Overview
PbC® Technology
The full technical description of Axion's proprietary PbC® technology is a "multi-celled asymmetrically supercapacitive lead-acid-carbon hybrid battery." Like a lead-acid battery, our battery consists of a series of cells. Within the individual cells, however, our construction is more complex. Where the negative electrodes in lead-acid batteries are simple sponge lead plates, our negative electrodes are five-layer assemblies that consist of a carbon electrode, a corrosion barrier, a current collector, a second corrosion barrier and a second carbon electrode. These electrode assemblies are then sandwiched together with conventional separators and positive electrodes to make our battery, which is filled with an acid electrolyte, sealed and connected in series to the other cells.
We have been testing laboratory prototypes of Axion's PbC® batteries since April 2004. Our test protocol requires a complete charge-discharge cycle every 7 hours to a 90% depth of discharge. During testing, our laboratory prototypes have withstood more than 1,600 cycles before failure. In comparison, most lead-acid batteries designed for deep discharge applications can only survive 300 to 500 cycles under these operating conditions. Based on the work completed during the laboratory development stage, we believe our application specific prototypes will offer several key performance advantages over conventional lead-acid batteries, including:
- significantly higher power delivery rates;
- significantly faster recharge rates;
- significantly longer cycle lives in deep discharge applications; and
- minimal required maintenance.
Over five years have been devoted to research and development on various aspects of this technology. Our work has focused on developing our intellectual property, characterizing baseline performance, developing proprietary treatment processes for the activated carbon we use in our electrodes, developing proprietary designs and manufacturing techniques for electrode assemblies and fabricating a series of material and design evaluation prototypes that range from single cell to multi-cell batteries.
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