Controllable solid electrolyte interphase precursor for stabilizing natural graphite anode in lithium ion batteries

Solid electrolyte interface (SEI) precursor is a new concept to replace the complicated and undesirable electrolyte additive in the state-of-the-art lithium ion batteries. Herein, a new and effective strategy of SEI precursor is realized by applying functional nano 2, 2-dimethylethenylboronic acid (DEBA) film on natural graphite surface. The functional nano layer contributes to the development of a stable and controllable SEI via in-situ self-polymerization between the DEBA molecules on graphite surface during the cell formation. With 20 nm DEBA layer, the natural graphite anode exhibits significantly enhanced electrochemical performances in terms of the first coulombic efficiency, rate capability and cycling performance. Meanwhile, the life-span of the full cell with LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode is also significantly prolonged and the result is superior to using traditional electrolyte additive of LiODFB. The underlying mechanism lies in the on-site SEI formation and suppressed growth of the SEI film during long-term cycles.