EaglePicher (Canada)

In-situ exploration of Venus is seriously hampered by its severe environment, which is benign (28oC) at an altitude of 55 km, but rapidly becomes hostile, with increasing temperature and CO2 pressure at lower altitudes, eventually reaching ~465°C and 90 bars at the surface.1 These challenging conditions have limited the previous Venus surface missions, e.g., the Russian Venera series and Vega-2 Landers,2 to barely two hours after deployment with lithium-primary batteries, despite the use of considerable insulation, phase-change materials, and similar heat sinks to isolate batteries and avionics from high surface temperatures. The recent decadal survey, ‘Vision and Voyages for Planetary Science in the Decade as well as the more recent Venus Exploration and Analysis Group (VEXAG) study3 emphasized the need to gather basic information on the crust, mantle, core, atmosphere/exosphere, and bulk composition of Venus, to understand the evolutionary paths of Venus in relation to Earth and recommended long-duration landers and probes for future missions.In order to enable extended surface missions on Venus, e.g., landers, probes and seismometers, NASA has initiated the development of high temperature electronics and power technologies, under its ‘Hot Operating Temperature Technology’ (HOTTech) program. Under this program, we have been developing advanced primary batteries resilient to the hostile conditions on the Venus surface and operational for several days with high specific energy (>100 Wh/kg) and energy density (>150 Wh/l). Here, we will describe the development of high temperature batteries based on lithium alloy (e.g., Li-Al) anodes, molten salt electrolytes containing binary/ternary mixtures of alkali metal halides, cathodes consisting of transition metal sulfides, and designs similar to the aerospace thermal batteries.4 With FeS cathode and appropriate changes in the electrolyte, binder and active material ratios, we have demonstrated the operation of the high temperature battery in prototype cells for 30 days in primary mode, and >150 days in rechargeable mode at 475oC. Further, with suitable thin coatings of inorganic compounds, e.g., Al2O3, AlF3 and AlBO3 on the cathode particles, the utilization of the cathode, and hence the operational life of the cells have been improved by another 50%.AcknowledgementsThe work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA) and supported by the NASA’s HOTTech project. The information in this document is pre-decisional and is provided for planning and discussion only.References Basilevsky, J. W. Head, "The surface of Venus". Rep. Prog. Phys. 66, 1699 (2003).Gilmore, et al., “Venus Surface Composition Constrained by Observation and Experiment”, Space Sci. Rev. 212, 1511–1540 (2017); doi:10.1007/s11214-017-0370-8.A. Bullock, et al., “A Venus Flagship Mission: Report of the Venus Science and Technology Definition Team," 40th Lunar and Planetary Science Conference (Lunar and Planetary Science XL), The Woodlands, TX, March 23-27 (2009).E. Glass, J.P. Jones, A. V. Shevade, D. Bhakta, E. Raub, R. Sim, R. V. Bugga, “High temperature primary battery for Venus surface missions”, J. Power Sources. 449, 227492 (2020). doi:10.1016/j.jpowsour.2019.227492.

In the flesh (skinless fillet) of chinook, chum, coho, pink, and sockeye salmon (Oncorhynchus tshawytscha, O. keta, O. kisutch, O. gorbuscha, and O. nerka, respectively), sablefish (Anoplopoma fimbria) and walleye pollock (Theragra chalcogramma) from several sites in the northeast Pacific sampled between 2002 and 2008, tetra- and pentabrominated diphenyl ethers (BDEs) (BDE 47, 49, 99, and 100) dominated the congener distribution. Chinook and sablefish contained the highest concentrations, followed by sockeye, coho, and pink salmon, and pollock. In sockeye from the Bering Sea - Aleutians and from the Gulf of Alaska, total tri- to hepta-BDE concentrations fell significantly between 2002 and 2005; in sablefish from Gulf of Alaska, there was a steady but statistically nonsignificant decline in BDE concentrations between 2002 and 2008. Relative proportions of the main BDE congeners did not change appreciably over time, within species or location. All species except sockeye salmon showed a clear southeastward increase in BDE concentrations, implying an increasing gradient in general ecosystem contamination. In chinook, coho, and sablefish, especially, the southeastward trend in increasing total concentrations was associated with increasing proportions of BDEs 47 and 100. Chinook returning to western North American natal streams appeared to accumulate most of their PBDE burden towards the end of their migration. Fish from more northern sampling sites often had higher proportions of more highly brominated congeners than those from more southern sites, perhaps reflecting contamination from Asian sources where higher-brominated commercial PBDE formulations are used. In sablefish and pollock, the relative proportions of BDEs 99 and 47 varied inversely in almost a 1:1 ratio, implying debromination of BDE 99 to 47.

<div class="htmlview paragraph">With increased use of Lithium-Ion (Li-ion) batteries in military and space applications, it is important to understand individual cell performance. The performance of the individual cells in a four cell, 45 ampere hour (Ah) Li-ion battery was obtained through repeated cycle testing. To show the effects of cell equalization, the battery was subjected to multiple charging cycles with and without cell equalization. Initially, the battery was subjected to 15 cycles of bulk charge, cell equalization and battery discharge. These cycles were followed by 700 cycles of bulk charge and battery discharge. Battery testing was completed with 187 cycles of bulk charge, cell equalization and battery discharge.</div>

<div class="htmlview paragraph">The brake insulator performs a significant function when properly designed in controlling the brake system high frequency dynamic instabilities leading to brake squeal. The second major challenge is thermal management. It provides the direct heat flow, storage and corresponding temperature differential profile between the rotor and piston. Suboptimal thermal control can lead to lower operational bands of damping outside of the peak loss factor range, variation in modal dynamics with temperature, heat aging and degradation of elastomer/visco-elastic polymer physical properties [<span class="xref">2</span>, <span class="xref">3</span>]. Design of the insulator is dictated by the unique squeal signature (and associated thermal cycles) specific to the brake corner architecture. Short time frame insulator solutions are typically required in the later development stages with no latitude for design modification flexibility.</div> <div class="htmlview paragraph">The use of numerical approximation and semi-empirical tools provide the flexibility to address compressed development time. This allows provision for a greater number of alternative solutions to be assessed and significant reduction in hardware and test resources and time during the insulator selection process. This paper demonstrates efficiencies obtained through integration of the underlying thermal and Oberst based beam based theories with empirical data results to provide directional guidance of alternative designs and the ability to synthesize data from existing results without additional testing.</div>

Eagle-Picher Energy Products (EPEP) has been manufacturing and testing large lithium ion cells (up to 100-Ah) for several years. Recently, work has focused on the testing of different chemistries at variable temperatures and designing and fabricating 100-Ah cylindrical cells. For the aircraft application the largest concern is irreversible capacity loss at elevated temperatures (70/spl deg/C). In contrast, for the aerospace application shelf-life and cycle life are critical. EPEP has found that the major contributor to the loss in low temperature performance due to high temperature testing, was the positive electrode. EPEP discuss recent results of variable temperature cycling and 100-Ah cell performance.

The effect of sodium iodide and sulfur additives on the performance of Na/β′′-alumina/NaAlCl4/NiCl2/Ni cells was investigated in quasi-sealed laboratory research cells (0.5–1.0 Ah capacity) and in sealed full-size cells (4 Ah capacity). It was found that sodium iodide additive especially in combination with sulfur in Na/NiCl2 cells significantly increases the usable capacity and reduces the impedance of the Na/NiCl2 cells. It is proposed that the use of sodium iodide enhances the energy and power performance of the NiCl2 electrode by two different mechanisms. The first mechanism, iodide ion doping of the anodically formed solid NiCl2, is dominant at potentials lower than that of iodine evolution. The doping effect of the iodide ions produces a higher-capacity, lower-impedance NiCl2 layer on the positive electrode. The second mechanism, anodic formation of very reactive iodine species, is effective when the cell is cycled through the iodine evolution potential range (2.8–3.1 V vs Na). During this process, the dissolved iodine species improve electrode kinetics through liquid-phase mass transport. Use of the sodium iodide additive is safe in sealed cells, causing no over-pressurizing problems. A maximum pressure increase of only 10 kPa was detected by a pressure sensor during severe overcharge tests.

Deep level characterization of a ZnSe Schottky diode grown by the seeded physical vapor transport (SPVT) method is presented for the first time. Deep level transient spectroscopy (DLTS) measurements reveal a deep electron trapping level with an activation energy of (0.34 ± 0.01) eV and a concentration of 1.01 × 1012 cm−3. Through the use of short fill pulses and curve fitting, several lower concentration peaks are also characterized. These are found to have concentrations on the order of 1010 to 1011 cm−3 and activation energies ranging from 0.096 to 0.383 eV. Tiefe Störstellen einer ZnSe-Schottky-Diode, die mit Hilfe des seeded physical vapor transports (SPVT) hergestellt wurde, werden hier zum ersten Mal präsentiert. Messungen der deep level transient spectroscopy (DLTS) zeigen ein tiefes Elektronenhaftstellenniveau mit einer Anregungsenergie von (0,34 ± 0,01) eV und einer Konzentration von 1,01 × 1012 cm−3. Mit Hilfe von kurzen Füllpulsen und Kurvenanpassungen werden außerdem einige Peaks geringerer Konzentrationen charakterisiert. Die Konzentrationen dieser Peaks liegen in der Größenordnung von 1010 bis 1011 cm−3 mit Anregungsenergien zwischen 0,096 und 0,383 eV.