1,4-Dicyanobutane as a film-forming additive for high-voltage in lithium-ion batteries

Layered structure LiNi0.5Co0.2Mn0.3O2 (NCM) cathode has been considered as a higher energy density candidate, but the problems of high voltage cycling resistance hinders its further application. Herein, we report a Nitrile (-CN) group 1,4-Dicyanobutane (ADN) as a film forming additive. Linear sweep voltammetry (LSV) tests have shown that EC/EMC based electrolytes with ADN have higher oxidation potentials ( > 6.2 V vs. Li/Li+). The LiNi0.5Co0.2Mn0.3O2/graphite full cells containing 0.5 wt% ADN showed significant high voltage cycling performance with a capacity retention of 85.2%, while the blank electrolyte after 120 high voltage cycles was 67.96%. This is attributed to the protective effect of SEI film prevents the further decomposition of electrolyte and transition metal ion dissolution, thus stabilizes the electrode-electrolyte interface. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results also demonstrate less unwanted lithium compounds absorbed on the ADN-contained cathode corresponding to fewer side reaction.