Electrodeposition experiments in microgravity conditions

Abstract

Metal electrodeposition may produce irregular deposits with various morphologies. For liquid electrolytes a precise study of these deposits may be complicated by convective motion due to buoyancy. Zero-gravity (0g) conditions provided by parabolic flights give a straightforward mean to avoid this effect: we present here 0g electrodeposition experiments, that we compare to ground experiments (1g). Two electrochemical systems were studied by laser interferometry, allowing to measure concentration variations in the electrolyte: copper deposition from copper sulfate aqueous solution and lithium deposition from an ionic liquid containing LiTFSI. For copper, concentration variations were in good agreement with theory. For lithium, an induction time was observed for the concentration evolution at 1g: due to this induction time and to the low diffusion coefficient in the ionic liquid, concentration variations were hardly measurable in the parabolic flight 0g periods of 20 seconds.