1,3,6-Hexanetricarbonitrile as electrolyte additive for enhancing electrochemical performance of high voltage Li-rich layered oxide cathode

1,3,6-Hexanetricarbonitrile (HTN) has been investigated as an electrolyte additive to improve the electrochemical performance of the Li1.2Ni0.13Co0.13Mn0.54O2 cathode at high operating voltage (4.8 V). Linear sweep voltammetry (LSV) results indicate that HTN can improve the oxidation potential of the electrolyte. The influences of HTN on the electrochemical behaviors and surface properties of the cathode at high voltage have been investigated by galvanostatic charge/discharge test, electrochemical impedance spectroscopy (EIS), and ex-situ physical characterizations. Charge-discharge results demonstrate that the capacity retention of the Li1.2Ni0.13Co0.13Mn0.54O2 cathode in 1% HTN-containing electrolyte after 150 cycles at 0.5 C is improved to 92.3%, which is much higher than that in the standard electrolyte (ED). Combined with the theoretical calculation, ICP tests, XRD and XPS analysis, more stable and homogeneous interface film is confirmed to form on the cathode surface with incorporation of HTN, meanwhile, the electrolyte decomposition and the cathode structural destruction are restrained effectively upon cycling at high voltage, leading to improved electrochemical performance of Li1.2Ni0.13Co0.13Mn0.54O2 cathode.