Degradation Mechanisms in NMC-Based Lithium-Ion Batteries

Battery electric vehicles are a cost intensive investment, caused by the energy storage systems, which are themselves dominated by the battery cell costs. To ensure the economic feasibility, the lifetime needs to be well known. Degradation in lithium-ion batteries is typically studied at the anode, whereas cathodecentered research is driven by higher energy densities. In contrast to this, the degradation mechanisms of the cathode are analyzed on a physical level in this work and then correlated to the capacity loss and resistance increase of the battery. Thestudies are based on accelerated aging tests on a Commercial high energy lithium-ion cell. The electrodes were analyzed for structural degradation, dissolution and surface layer formation. It was possible to identify and quantify processes at the cathode that have a major influence on the degradation behavior of the battery