Structural response of silicon-containing graphite anodes on lithium intercalation

Abstract

This study investigates the impact of silicon content in the graphite anode of cylinder-type Li-ion batteries using operando neutron powder diffraction techniques. A batch of four different Li-ion cells is analyzed, with a focus on the structural response of active cell components during electrochemical cycling. The results indicate that high silicon content in the graphite anode causes a delay in the initial lithiation of graphite, shifting it towards higher voltages independent of the cell's internal resistance. Differential voltage, incremental capacity analyses and quantitative energy-dispersive X-ray spectroscopy, corroborate these structural changes. Additionally, X-ray diffraction computed tomography using a µm-sized synchrotron beam revealed local structural degradation and lithiation inhomogeneity in the high silicon content cells during cycling.