Development and Evaluation of High Specific Energy Li/CF _x Cylindrical Battery Cells for Space Applications

Cylindrical Li/CF x battery cells were developed and evaluated for use in robotic space applications. These cells feature lithium anodes coupled with high specific capacity (∼865 mAh g −1 theoretical value) fluorinated carbon or CF x cathodes (where x∼1). The development efforts targeted achieving a cell level specific energy of >700 Wh kg −1 (when discharged at moderate rates at 20 °C) in a hermetically sealed D-sized cell format, at a typical discharge voltage of ∼2.6 V. The Jet Propulsion Laboratory collaborated with two different vendors (EaglePicher Technologies and Rayovac) to develop these cells, through the use of high loading CF x cathodes to maximize the delivered capacity combined with aluminum packaging to reduce cell mass (relative to traditional stainless steel designs). Cells were tested over a range of relevant rates and temperatures, to establish performance characteristics. Constant current discharge tests were performed under pulse conditions to extract the internal cell resistance, and three-electrode cells were prepared and tested to study the effects of depassivation and aging. Thermal power generation was measured under both open circuit voltage conditions (using microcalorimetry) and at different discharge rates (using isothermal calorimetry). Thermal imaging was also performed, to estimate cell temperatures during discharge.