Oxidation and combustion of stabilized lithium metal powder (SLMP)

Power systems based on combustion are of interest for space missions where the use of solar and nuclear energy is impractical. A novel design of such systems involves the so-called filtration combustion of metal powders with oxygen supplied by a chemical oxygen generator. In missions to Mars and Venus, the atmospheric CO 2 could be added to the oxygen flow. A stabilized lithium metal powder (SLMP) is a promising fuel for this application, but its oxidation and combustion in O 2 and CO 2 has not been studied yet. In the present work, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been used to investigate high-temperature oxidation of SLMP in O 2 /Ar and CO 2 environments. Further, combustion of SLMP in vertical quartz tubes with two open ends at natural infiltration of O 2 and CO 2 has been studied in a laser ignition facility. The TGA has revealed the formation of lithium peroxide (Li 2 O 2 ) in addition to lithium monoxide (Li 2 O) at temperatures below 400 & DEG;C. Scanning electron microscopy has shown that the oxidized particles are hollow shells, which implies that the oxidation process includes growth of a solid oxide layer on the surface of the lithium droplet and simultaneous growth of a cavity inside the droplet. The laser ignition of SLMP in O 2 results in vigorous combustion of the top layer followed by the downward propagation of a counterflow combustion wave. The TGA and DSC have shown that the reaction of SLMP with CO 2 is a multi-stage process, which includes the formation of lithium oxide and its subsequent conversion into lithium carbonate (Li 2 CO 3 ). Self-sustained combustion of SLMP was not achieved in a CO 2 environment, apparently because the formed products hinder the transport of CO 2 .& COPY; 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Power systems based on combustion are being explored as an alternative in space missions where solar and nuclear energy are impractical. This study investigates the oxidation and combustion behavior of stabilized lithium metal powder (SLMP) in oxygen and carbon dioxide environments. Thermogravimetric analysis and differential scanning calorimetry were performed, indicating the formation of lithium peroxide and lithium monoxide at different temperatures. Laser ignition experiments were also conducted in a CO2 environment, but self-sustained combustion of SLMP was not achieved due to hindrance from the formed products.