Science and Technology Supporting National Security
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This work created a database for tracking data analysis files from multiple lab techniques and equipment stored on a central file server. Experimental details appropriate for each file type are pulled from the file header and stored in a searchable database. The database also stores specific location and self-directory structure for each data file. Queries can be run on the database according to file type, sample type or other experimental parameters. The database was constructed in Microsoft Access and Visual Basic was used for extraction of information from the file header.
Li/SOCl{sub 2} battery technology is attractive by virtue of its high energy density, low self-discharge rate, and ability to to perform well at a wide variety of discharge rates. However, some of these same attributes also make Li/SOCl{sub 2} cells capable of hightly exothermic events when handled under abnormal conditions. We manage the energy safely and optimize the performance by tailoring the design to the application. We have developed three different ``D`` size cells that target low, moderate, and high rate applications. Each design provides safe and efficient performance, although, in progressing from low to high rate capability, the likelihood of venting under abuse conditions increses. We incorporate a vent mechanism in all designs as the ultimate protection from severe abuse. The details of our battery designs and the benefits of application-specific design are discussed.
We have developed a Li/SOCl{sub 2} ``D`` cell for applications requiring 10 to 15 years life at very low drain rates, typically less than 150 {mu}A. Maximizing cell safety and reliability, while delivering very good energy density, have been the goals of our study. We have achieved these goals by designing the cell to be application specific. The low-rate cell has been optimized to deliver up to 16 Ah at drain rates of less than 70 mA. By virtue of its low surface area, 145 cm{sub 2}, the cell has demonstrated excellent safety behavior. Safety testing has been performed on individual cells as well as on two-cell and four-cell batteries. Single cells did not vent when short-circuited. We were able to produce benign venting in a two cell string, but only when the string was partially discharged before shorting. The vent mechanism is a 300 psi rupture pressure burst disc manufactured by BS&B Safety Systems. We define benign venting as full opening of the 3/8 in. dia vent hole without deformation of the case. Material is expelled from the cell without flame, and the cell stack remains largely intact. We have not produced venting of the Sandia-designed low rate cell under any other abuse test conditions. The vent functions as an ultimate safety mechanism in the case of severe abuse, but resistance to venting under normal use and mild abuse conditions is key to the achievement of high reliability.