A novel electrolyte additive for improving the interfacial stability of high voltage lithium nickel manganese oxide cathode

In this work, we propose a novel electrolyte additive phenyl trifluoromethyl sulfide (PTS) to improve the interfacial stability of high voltage lithium nickel manganese oxide (LiMn_1.5Ni_0.5O₄) cathode/electrolyte. At 1C rate, addition of 0.5% PTS improves the capacity retention of LiNi_0.5Mn_1.5O₄ from 65% to 84% after 450 cycles at room temperature, and from 64% to 95% after 100 cycles at evaluate temperature. Density functional theory calculation and experimental characterization demonstrate that PTS oxidizes preferentially to the carbonate base electrolyte, generating a SEI film, which effectively suppresses the continuous decomposition of carbonate base electrolyte and the structural destruction of LiMn_1.5Ni_0.5O₄.