Search

High energy density lithium-ion batteries using Ni-rich cathode (such as LiNi0.6Co0.2Mn0.2O2) suffer from severe capacity decay. P-toluenesulfonyl fluoride (pTSF) has been investigated as a novel film-forming electrolyte additive to enhance the cycling performances of graphite/LiNi0.6Co0.2Mn0.2O2 pouch cell. In comparison with the baseline electrolyte, a small dose of pTSF can significantly improve the cyclic stability of the cell. Theoretical calculations together with experimental results indicate that pTSF would be oxidized and reduced to construct protective interphase film on the surfaces of LiNi0.6Co0.2Mn0.2O2 cathode and graphite anode, respectively. These S-containing surface films derived from pTSF effectively mitigate the decomposition of electrolyte, reduce the interphasial impedance, as well as prevent the dissolution of transition metal ions from Ni-rich cathode upon cycling at high voltage. This finding is beneficial for the practical application of high energy density graphite/ LiNi0.6Co0.2Mn0.2O2 cells.

Improving the interphasial stability of electrode/electrolyte is crucial to the large-scale applications of lithium-ion battery with high energy density. Herein, a novel electrolyte additive, phenyl trans-styryl sulfone (PTSS), is proposed to reconstruct the interphasial structure and composition of electrode/electrolyte and to improve the cyclic stability of high voltage LiNi0.8Co0.1Mn0.1O2 (NCM811)/graphite full-cell. Specifically, the cell with PTSS additive maintains 63% of its initial capacity after 100 cycles at 1C, which is about 15% higher than that of baseline electrolyte. Theoretical calculation and experimental characterization reveal that the high electrochemical reactivity PTSS decomposes prior to the baseline electrolyte, generating a protective film on NCM811 cathode and graphite anode surface. The uniform and thin CEI film effectively enhanced the interphasial stability of NCM811 cathode via suppressing electrolyte oxidation and electrode interphasial destruction during long term cycling. In addition, the PTSS induced-SEI film enhances the interphasial stability of graphite anode.