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Technical Paper

Transition Metal Fluoride Cathodes for Lithium Thermal Batteries

A research and development program is being conducted at the Saft Advanced Technologies Division in Hunt Valley, Maryland, to double the energy density of a thermal battery. A baseline battery has been developed with lithium/iron disulfide chemistry to meet a set of military requirements. A study of transition metal fluoride cathodes to replace iron disulfide is in progress for an improved battery. Development of a lithium/copper(II) fluoride (CUF2) couple is proceeding by iterative testing of single cells. LiAl/CuF2 cells have produced 227 Wh/kg. This exceeds the specific energy of state-of-the-art cells with iron disulfide by nearly 40%. The copper fluoride cells average 2.44 volts when discharged at a current density of 200 mA/cm2.
Technical Paper

Lithium Ion Batteries: Power Sources for Military Aircraft

Rechargeable lithium ion batteries provide significant advantages over lead acid and nickel cadmium batteries for manned and unmanned aerial vehicles. Lithium ion has excellent cycle life and calendar life and exceptionally low self-discharge. The high energy density of lithium ion provides weight and volume savings, which allows for additional aircraft payload. Cell configurations containing high surface area electrodes and low temperature electrolyte can provide required power over military temperature extremes of −40°C to +71°C. Such batteries provide engine starting, load leveling, switching, and emergency aircraft power. Prototype batteries have been tested to fighter aircraft loads and floated on a 28-volt bus. Hermetically sealed cell construction and electronic cell balancing and charge control provide maintenance free operation. Our solutions are cylindrical cells in high energy and high power configurations.
Technical Paper

Lithiated Transition Metal Oxide Cathodes in Molten Nitrate Electrolytes for Lithium Thermal Batteries

A study of transition metal oxide cathodes to replace the iron disulfide used in thermal batteries was conducted at Saft ABSD in Cockeysville, MD. The goal was to identify cathode materials yielding higher voltage and improvements in energy density. Selected materials were evaluated versus lithium immobilized by iron powder (LAN) anodes in molten nitrate electrolytes. Single cells were tested between heated platens inside an argon atmosphere glove box over the temperature range of 240°C to 425°C. The best cathode material tested was lithiated manganese dioxide, LiMn2O4. After extensive experimentation, we were able to achieve a peak voltage of 2.8 V under a load of 200 ma/cm2 and a two-plateau voltage discharge yielding 221 Wh/kg at 260°C. This exceeds the specific energy of state-of-the-art cells with iron disulfide.
Technical Paper

Thermal Batteries, Their Technologies and Applications

Thermal batteries are primary reserve energy sources consisting of an alkali-metal and a transition metal chalcogenide electrochemical couple in a fused salt electrolyte. The electrolyte is solid and non-conducting at ambient temperatures and melts after integral pyrotechnic heat sources are ignited by a percussion primer or electro-explosive device. From their inception thermal batteries have proven superior for applications which require long shelf life, high reliability, imperviousness to dynamic environmental conditions and extremely high power. Primary applications include power for guidance and control, warhead fusing and telemetry for missiles. Recent improvements in specific energies and energy densities up to 70 Wh/kg and 155 Wh/l have opened new applications for aircraft emergency power and torpedo propulsion.
Technical Paper

Development Of A Prototype Lithium Ion Battery for the F-16, F-18, and F-117 Aircraft

Development of a lithium ion battery that will meet the requirements of all three aircraft, F-16, F-18, and F-117, is on going at the SAFT Research and Development Center in Cockeysville, MD. Seven high power cells, type HP47178, are connected in series to provide 28VDC and a C rate capacity of 16Ah. This cell pack fits into the smallest volume of the three aircraft, which is the 7.5 Ah lead acid box used on the F-18. Cell construction consists of spiral wound thin electrodes in a cylindrical steel case. The case negative design employs a center hole for improved thermal management. The battery containing cells with low temperature electrolyte meets the required F-16 duty cycle at temperatures from −20°C to +71°C. At −30°C the voltage is marginal. Lower temperatures down to −40°C will require heaters. The weight and volume of the lithium ion cell pack is considerably less than the nickel cadmium and lead acid batteries that would be replaced.