Speaker
Description
The increasing number of space debris has become problematic for the sustainment of space activities in Earth orbit. Several spacecraft breakups have been observed in the past and some of them are due to a battery breakup. In order to mitigate the risk to generate debris in the future, passivation of the spacecraft after end of mission is now required. One way to achieve passivation is to deplete the spacecraft battery. However if the latter is to be implemented a very careful assessment of the behaviour of the battery at such conditions should be made, because, how can we be sure that the battery is 100% safe once depleted?
Such an assessment can be very complex considering that temperature, radiation, state of charge and ageing of the battery could play a role among other parameters on the risk and possibility of battery explosion. The actual probability of a thermal runaway leading to a cell explosion is impossible to assess without testing. The ESA TRP objective, performed in collaboration with Airbus DS, SAFT, ABSL and CEA, is to understand and demonstrate through testing the behaviour of a spacecraft lithium-ion battery under extreme conditions which the battery can experience after EoM or during/after passivation if any. More than 200 battery cells used in spacecraft batteries, both fresh and aged, have been tested from an early stage of the project in 2016 and so far in order to assess the impact of ageing during LEO and GEO missions under harsh conditions in space that the battery might experience.
The tests performed in this TRP include External short-circuit, Internal short-circuit, Over-charge, Over-discharge, Accelerating Rate Calorimetry (ARC) test, Over-temperature test and Micrometeoroids. Cells and modules from the two main battery manufacturers in Europe, ABSL and SAFT, are used for testing including ABSL18650-HC, -HCM, -NL and SAFT VES16, VES140, VES180. The test campaign is currently coming to an end along with a series of recommendations for passivation strategies to ensure battery safety.
