Proof-of-Concept Molten Lithium–Selenium Battery

Abstract

Most space missions utilize energy storage, such as a rechargeable battery onboard the spacecraft. Therefore, a continuing evolution of battery performance can benefit a wide gamut of space science missions conducted or planned by NASA and worldwide space agencies. Venus presents the most significant challenge to energy storage systems due to a combination of high temperature (465 °C) and the presence of corrosive gases (CO2, CO, SO2, and N2). On a NASA-funded project, a high-temperature (465 °C) lithium–selenium (Li∥Se) battery consisting of an anode of molten Li, a lithium-ion conducting ceramic electrolyte (garnet-type Li6.4Al0.2La3Zr2O12, LLZO), and a cathode of Se have been conceptualized. The proof-of-concept Li∥Se cells were built using baseline cell electrodes, electrolytes, and cell design. The fabricated Li∥Se cell was tested in an in-house built cell holder placed in an argon-filled glovebox. Electrochemical testing includes time-dependent open-circuit voltage measurements across a wide temperature range (230–500 °C) and electrochemical cycling at multiple current rates at 465 °C. Further cell components and design optimization will enable higher current charge–discharge and a longer battery life span over a wide temperature range. In addition, the use of high-energy electrodes will encourage long-duration and safe Venus surface exploration.