N121-007 TITLE: Low-Temperature/High-Voltage Thermal Battery

TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes, Weapons

ACQUISITION PROGRAM: PMA 264

OBJECTIVE: Develop a high-voltage thermal battery with a low operating temperature to increase battery operating life and safety.

DESCRIPTION: Standard thermal batteries operate at temperatures between 310 degrees Celsius and 500 degrees Celsius. These batteries are used in systems capable of handling such high temperatures without resulting in damaged electronic components, or possibly in ignition or degradation of sensitive materials located within the battery�s vicinity. However, there is a need for batteries that do not operate at such high temperatures and have an operating life of over 20 years. Low operating temperature thermal batteries would have a longer life and would be safer; in addition, they would result in decreased overall material cost, battery case temperature, and battery size.

Miles et al. conducted work by using molten nitrate electrolytes as a viable low- temperature alternative to current electrolytes. They observed that the main problem of using molten nitrate electrolytes was contamination by chloride ions, sodium ions, and moisture. In particular, moisture contamination results in the evolution of hydrogen gas and, therefore, a very unstable battery.

General requirements for developing a high-voltage thermal battery with a low operating temperature include identifying suitable materials for the anode, cathode, electrolyte, and the material that will supply heat to melt the electrolyte. The electrolyte melting temperature should be between 100 degrees celcius and 230 degrees celcius. A single-cell battery must have the following performance characteristics that are equal to or better than current technology: voltage >2 V, current density >0.5 A/cm2, and current pulse >6 A/cm2. The batteries will be tested in operational and non-operational environments and undergo U.S. Navy safety testing.

PHASE I: Identify suitable materials for the anode, cathode, electrolyte, and the material that will supply heat to melt the electrolyte. Test a single-cell battery with the following design. Performance characteristics that are equal to or better than current technology: voltage >2 V, current density >0.5 A/cm2, and current pulse >6 A/cm2.

PHASE II: Develop a full-size prototype battery with at least 30 V, maintaining current density >0.5 A/cm2 and current pulse >6 A/cm2. Demonstrate battery performance by testing a sample of batteries meeting performance requirements of an actual missile system. Fully document all fabrication, test processes, test data, and results.

PHASE III: Transition technology to commercial and military applications.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Temperatures observed in boreholes for oil and gas drilling exploration are in the temperature range of this SBIR, and hence the battery developed can be used as power supply for measurement equipment.

REFERENCES:
1. Briscoe, J. (June 8-11, 1998). An improved thermal battery for military applications. Proceedings of the 38th Power Sources Conference, p. 23. Cherry Hill, NJ.

2. Briscoe, J. and Castro, G. (April 6-8, 1999). Transition metal fluoride cathodes for lithium thermal batteries. 99-APSC-40, Proceedings of SAE Aerospace Power Systems Conference. Mesa, Arizona.

3. Miles, M. H. (June 12-15, 2000). Lithium thermal batteries using molten nitrate electrolytes. Proceedings of the 39th Power Sources Conference, pp. 560-563. Cherry Hill, NJ.

4. Miles, M. H., Grumet, A. A., & Solomon K. U.S. Patent 7629075, issued December 8, 2009.

KEYWORDS: Thermal Battery, Low Operating Temperature, Cathode, Anode, Electrolyte, Nitrate

** TOPIC AUTHOR (TPOC) **

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