Given that X-ray diffraction is not surface-sensitive, XPS was employed to investigate the surface characteristics of both the pristine and recycled electrode materials. The primary focus of this analysis was the In 3d spectrum, aiming to assess the formation of indium-rich layers or precipitates on the electrode surface during recycling. Additionally, the chemical states of transition metals were examined to identify surface-related changes indicative of potential degradation process. values reported in literature . The layered electrode materials (e.g. LCO, NMC, and NCA) exhibit additional indium-containing species, including In-OH (e.g., In(OH)3) and In-Cl (e.g., InCl3) , indicating the presence of these species at the surface, in contrast to spinel-type (e.g., LTO and LMO) and olivine-type materials (C-LFP). This observation aligns with the increased amounts of LiCl alongside the targeted Li3InCl6 phase, as shown in Figure and discussed in the previous section. The mechanism underlying the formation of the In-rich surface layer is further elaborated in section 3.4.