A Functional Electrolyte Containing P-Phenyl Diisothiocyanate (PDITC) Additive Achieves the Interphase Stability of High Nickel Cathode in a Wide Temperature Range.

The lithium-ion batteries (LIBs) with high nickel cathode have high specific energy, but as the nickel content in the cathode active material increases, batteries are suffering from temperature limitations, unstable performance, and transition metal dissolution during long cycling. In this work, a functional electrolyte with P-phenyl diisothiocyanate (PDITC) additive is developed to stabilize the performance of LiNi Co Mn O (NCM811)/graphite LIBs over a wide temperature range. Compared to the batteries without the additive, the capacity retention of the batteries with PDITC-containing electrolyte increases from 23 % to 74 % after 1400 cycles at 25 °C, and from 15 % to 85 % after 300 cycles at 45 °C. After being stored at 60 °C, the capacity retention rate and capacity recovery rate of the battery are also improved. In addition, the PDITC-containing battery has a higher discharge capacity at -20 °C, and the capacity retention rate increases from 79 % to 90 % after 500 cycles at 0 °C. Both theoretical calculations and spectroscopic results demonstrate that PDITC is involved in constructing a dense interphase, inhibiting the decomposition of the electrolyte and reducing the interfacial impedance. The application of PDITC provides a new strategy to improve the wide-temperature performance of the NCM811/graphite LIBs.