Verification of delayed permanent lithium intercalation into graphite interlayers by surface treatment of lithium-ion battery anodes

Li-ion batteries (LIBs) with high performance in terms of high capacity and stability are in increasing demand for applications in a variety of energy-related fields, including next-generation electric vehicles. In this regard, attempts have been made to form a stable and robust solid electrolyte interphase (SEI) on LIB anodes, which can stably maintain the cyclic process of Li ion insertion/extraction into/from the anode materials. In this study, we coat the surfaces of LIB anode materials consisting of graphite and Si with poly(vinyl alcohol)-phosphate to form a stable SEI layer with high ionic conductivity and apply Auger electron spectroscopy (AES) to clearly detect the Li_xC₆ (x < 1) phase generated by the permanent intercalation of Li into graphite interlayers. A comparative analysis based on AES clearly demonstrates that permanent Li intercalation into graphite interlayers is delayed by the oxide coating, resulting in both enhanced stability and reduced Li consumption at the anode.