Additive-induced robust interphases on the interface of LiNi_0.8Co_0.1Mn_0.1O₂ cathode for long-term stability of lithium-ion batteries at high voltage of 4.8 V

Nickel-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) material is anticipated to be the cathode material of the upcoming generation lithium-ion batteries (LIBs). Nevertheless, the actual use of NCM811 is limited by its structural instability under high voltage cycling. To enhance the NCM811 cyclic stability at a high voltage, we suggest an additive-induced strategy to create a robust interphase on electrode surface. The lithium difluorophosphate (LiPO₂F₂, LiDFP) additive decomposes on the electrode surface before the baseline electrolyte does. This decomposition creates a thin, uniform film known as the cathode-electrolyte interface (CEI). Through a series of experimental tests, it is found that the CEI film induced by LiDFP additive could effectively prevent electrolyte from decomposing and mitigate the strain and crack formation in the cathode. retains a high capacity of 91.8 % after 100 cycles at 4.8 V. This is significantly higher than the 73.3 % capacity retention observed with the baseline electrolyte. LiDFP oxidizes and decomposes before the electrolyte, forming a robust CEI film that mitigates NCM811 cathode strain/cracking, suppresses transition metal (TM) dissolution, and enhances NCM811 material stability.