The Solid Electrolyte Interphase a key parameter of the high performance of Sb in sodium-ion batteries: Comparative X-ray Photoelectron Spectroscopy study of Sb/Na-ion and Sb/Li-ion batteries

International audienceTo understand the origin of the better performance of Sb electrode i) vs Na than vs Li andii) formulated with CarboxyMethyl Cellulose (CMC) in water rather than withPolyVinylidene diFluoride (PVdF) in N-Methyl-2-Pyrrolidone (NMP), X-ray PhotoelectronSpectroscopy (XPS) and electrochemical tests have been carried out to carefully investigatethe chemical composition of the SEI layer formed at the Sb electrode surface in the Li- andNa-system, with the different binders. Sb electrodes were cycled using a standardEC/PC/3DMC (1M LiPF6) electrolyte containing Vinylene Carbonate (VC) andFluoroEthylene Carbonate (FEC) for Li system and a standard Propylene Carbonate PC (1MNaClO4) electrolyte containing FEC for Na system. Surface analysis was performed by acombined XPS core peaks and quantification data analysis to establish the main componentsof the Solid Electrolyte Interphase film (SEI). The key observation is that the thickness ofthe SEI layer is strongly related to the nature of the polymer binder used in the formulationand that its chemical nature is different in Li and Na batteries. Much favorable SEI in thecase of Sb-CMC/Na seems to participate to the excellent performance of this electrode