Following lithium distribution, intercalation and loss mechanisms during cycling of solid-state NCM-811 batteries using 2D, 3D and Bragg-edge neutron imaging

The main degradation mechanism leading to chemomechanical failure in Li-NCM-811 batteries is the large volume changes of the NCM-811 cathode material occurring during lithiation and delithiation. Although, in principle, this volume change is reversible, its anisotropic nature, in particular, leads to large stresses along the grain boundaries and ultimately to irreversible fracture of the secondary NCM particles. Therefore, a better understanding of the microstructural changes in relation to the electrochemical processes during battery cycling is crucial. In this experiment, the microstructural loss mechanisms and their relation to Li- transport will be studied through neutron imaging of the evolution of the NCM-811 material during operando dis-/charge cycling. In addition, Bragg-Edge imaging will provide details on the spatio-temporal evolution of the nano-scale de-/intercalation processes, the driving forces for the microstructural evolution. Consequently, the experiment will yield new multiscale understanding of the coupled electrochemo-mechanical processes that can help drive future battery development and simulation.