Interface adhesion properties characterization of sulfide electrode materials by the combination of BOLS and XPS

Although sulfide electrode materials in lithium battery systems have been intensively investigated due to their low-cost, high theoretical specific capacity, and energy density, there are few studies fousing on the adhesion properties, including the physical origin of hetero-coordination resolved interface relaxation, binding energy and the energetic behavior, and even the accurate quantitative information. In this paper, we present an approach for quantifying the interface adhesion properties of sulfide electrode materials resolved by the combination of bond order-length-strength theory(BOLS) and X-ray photoelectron spectroscopy(XPS), which has enabled clarification of the interface adhesion nature. The results show that the Cu 2p, Fe 2p, and S 2p electrons of Cu S and FeS_(2) compounds shift negatively due to the charge polarization of the conduction electrons of the heteroatoms, while Mo 3d, Sn 3d electrons of Mo S2 and Sn S2 and the C 1 s and S 2p electrons of CS compound shift positively due to the quantum trapping. It is noted that the exact interface adhesion energies of Cu S is 3.42 J m^(-2), which is consistent with the calculation result. The approach can not only clarify the origin of the interface adhesion properties of sulfide electrode materials,but also derive their quantification information from atomistic sites.