Degradation of Lithium-Ion Batteries in Aerospace

Kurzfassung

Lithium-ion batteries are the technology of choice for a broad range of applications due to their performance and long-term stability. The performance and durability of lithium-ion batteries is heavily impacted by various degradation mechanisms. These include the growth of the solid-electrolyte interphase (SEI) and the deposition of metallic lithium on the surface of the negative electrode, referred to as lithium plating. Long-term SEI growth is the biggest contributor to capacity fade in lithium-ion batteries. Lithium plating, which occurs in low temperature or high current charging, can result in capacity fade or even thermal runaway. In our group we develop multiphysical models and perform simulations for various types of batteries. In order to describe the internal processes of Li-ion batteries, we derive thermodynamic consistent transport theories [1]. Based on these, our group has developed models for long-term SEI growth [2,3] and for lithium plating in 3D electrode microstructures [4]. Such models predict battery performance over short time scales during single charging and discharging as well as battery degradation over long time scales during continued cycling. Finally, we want to understand the processes taking place in Li-ion batteries and observe them during battery operation. Here, we discuss perfomance and lifetime for the batteries of in-orbit satellite REIMEI [5]. To this end, we parameterize our model by comparing the electrochemical simulations to various experimental and in-flight data. By incorporating our new model for continued growth of the SEI [2], we simulate degradation in micro-structured electrodes in one and three dimensions. We are the first to understand experimentally observed inhomogeneities in the SEIs thickness throughout the negative electrode. Furthermore, our degradation model applies to battery storage as well as to battery cycling. We will further discuss lithium plating and perform state estimation of the REIMEI battery to predict its state-of-health in earth orbit.