High specific energy Lithium Sulfur cell for space application

Abstract

The battery energy density remains a key parameter accounting for the satellite mass budget. As illustration to this, the rechargeable battery still represents 100 to 200 of kilograms for a typical Eurostar 3000 satellite, which can represent up to 5% of the total mass, and about 100 kilograms for the next meteorological satellite program MetOp-SG. Any reduction in weight in these applications has therefore significant financial benefits, considering that the launch cost for such a satellite can be around 10k€/kg. Lithium-ion technology represented a revolution in terms of specific energy compared to Ni-Cd and is currently the most used and well suited for spacecraft. But it has also many drawbacks like price, some safety issues and its toxicity. Lithium-Sulfur (Li-S) cells are likely to become the next generation of energy storage to replace them. One of the reasons is that sulfur is an abundant element so it’s more affordable than cobalt used in Li-Ion cells. On top of that, Li-S cells are safer and more environmentally friendly. But the main advantage of this technology is the high energy density: around 5 times higher than Li-Ion cells. The major obstacle for application is due to dissolved polysulfide shuttling between anode and cathode. This phenomeno leads to permanent loss of active mass from the cathode into the electrolyte and onto the Li metal anode (passivating the Li anode with insoluble Li2S), severe self-discharge, low efficiency and fast capacity decay. Airbus DS has been testing and characterizing prototype Li-S cells manufactured by OXIS Energy Ltd. since 2014, demonstrating the potential and fast evolution of the cells performance. This paper presents the last test results on a set of different batches provided by OXIS and performed at Airbus DS premises in the frame of an ESA Innovation Triangle Initiative (ITI).