High Temperature Primary Battery for Venus Surface Missions

The hostile environment of high temperature and CO2 pressure has limited previous Venus surface mission durations to less than two hours giving only a glimpse of the Venus surface, despite the use of considerable insulation, phase-change materials, and similar heat sinks to isolate the payload and avionics from high surface temperatures. NASA has initiated studies to develop new power technologies that can tolerate the high Venus surface temperature of 465 oC and pressure of 92 bar, and operate for future long-duration Venus landers and probes. Such in-situ investigations are crucial to gather basic information on the crust, mantle, core, and bulk composition of Venus for understanding the evolutionary paths of Venus in relation to Earth. In this paper, we describe the development of high temperature primary batteries based on lithium alloy anodes, transition metal sulfide cathodes, and molten salt electrolytes. Among the various cathode materials examined for thermal stability and for electrochemical activity, FeS has emerged as the most suitable cathode. With optimized cell components, cell design, and operational parameters, laboratory test cells were fabricated, which demonstrated continuous operation of ~26 days at 475 oC. These batteries will enable new long-duration surface missions for detailed surface exploration of Venus.