John K. Erbacher

Aircraft Battery Design Concept for Improved Ultra Low Temperature Performance

Abstract : The AFRL, Electrochemistry and Thermal Sciences Branch has evaluated numerous aircraft battery designs and chemistries since the 1960s. Recent experiments on advanced battery chemistries have shown poor performance at ultra low temperatures below -20 deg C. Aircraft battery designs stress low weight and volume and maximum capacity. One design concept uses lower capacity cells in a series parallel configuration to reduce overall battery resistance and should also improve ultra low temperature performance. Our organization has begun experiments with series-parallel cell designs to evaluate the concept and to solve low temperature performance issues. Progress, observations on the effect of different chemistries, and the impact on aircraft battery characteristics are discussed.

Bipolar nickel-metal hydride aircraft battery with increased capacity and improved low temperature performance

Electro Energy, Inc. (EEI) has developed a bipolar Ni-MH wafer cell design that has the advantages of reduced weight, with increased capacity, high power and low temperature capabilities over conventional Ni-MH and competing technologies. These advantages make the EEI bipolar Ni-MH the battery of choice to replace the present F16/F18 and other military aircraft batteries. EEls present F-16 battery has 10% reduced weight in the same volume as the existing lead-acid battery, while having 21/2 times the capacity. EEls design of parallel stacks of thin wafer cells results in increased electrode surface area leading to improved high-rate and low temperature capability. The design has shown to be capable of operating at the Air Force minimum temperature requirement of -40°C. This has been achieved by optimizing each of the following variables: 1) metal-hydride alloy; 2) electrode capacity and surface area relationship; and 3) electrolyte composition. Supported by U.S. Air Force Manufacturing Technology Programs, EEI has focused on improving the performance of this battery, while scaling-up the manufacturing processes to meet the demands of the DoD and provide a cost competitive battery.

SAFT Li-ion Technology for High Rate Applications

Abstract : SAFT will present an update of its state-of-the art Very High Power (VHP) Lithium-ion (Li-ion) technology. The VHP cells are currently being qualified for use in military aircraft applications as well as in future military hybrid vehicles. Additionally, their use in Directed Energy Weapon (DEW) systems is also being explored.

Advances in Low Temperature Performance of Nickel-Metal Hydride Aircraft Batteries

The Air Force Research Laboratory (AFRL), Energy Storage and Thermal Sciences (PRPS) Branch has been developing nickel-metal hydride (Ni-MH) rechargeable batteries as an environmental replacement for existing valve regulated lead-acid (VRLA) and vented/sealed nickel-cadmium (VNC/SNC) batteries since 1995 and has evaluated cylindrical, prismatic and bipolar designs for this application. Recent advances in cell chemistry and design have resulted in a significant improvement in ultra low temperature performance indicating the suitability of these batteries for military aircraft applications over the temperature range from -40 °C to +65 °C. Results of the latest in-house tests of developments in bipolar and prismatic cell and battery designs indicate the current prismatic cell formulations are limited to temperatures above -25 °C while those used in bipolar designs operate over the full military aircraft temperature regime.

Nickel-metal hydride (Ni-MH) technology evaluation for aircraft battery applications

Available cylindrical and prismatic commercial Ni-MH batteries using AB/sub 5/ and AB/sub 2/ cathodes were evaluated for possible application to military aircraft batteries. Commercial AB/sub 5/ technology is further advanced than AB/sub 2/ technology and would require less alloy, electrolyte and single cell/battery development for near term (3-5 years) applications. Tested AB/sub 2/ technology appears inadequate to meet the near term military requirements and would require a major development in the alloy to overcome the irreversible capacity loss at temperatures above 49/spl deg/C. In addition, significant advances in alloy, electrolyte and single cell/battery development would also be needed.