Degradation Model and State Estimation for Lithium-Ion Batteries in Aerospace

Kurzfassung

Abstract 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. Based on these, our group has developed models for long-term SEI growth and for lithium plating in 3D electrode microstructures. In this contribution we develop a model to describe the performance and lifetime of the batteries of in-orbit satellite REIMEI developed by the Japan Aerospace Exploration Agency. Our new degradation model describes the growth of the solide electrolyte interphase (SEI) during battery storage as well as battery cycling. In our microstructure resolved three dimensional simulations we show inhomogeneities in the SEI thickness after cycling. To validate the model, we use experimental and in-flight data of the satellite’s batteries. Furthermore we incorporate the degradation model into an extended Kalman Filter for SOC and SOH estimation. In this way we estimate the battery states of the still operating satellite.