Anti-corrosive and surface-stabilizing functional electrolyte containing LiFSI and LiPO2F2 for SiO /NCM811-based batteries

Silicon oxide (SiO x ) has attracted considerable attention as an advanced anode material; however, SiO x becomes extensively pulverized during an electrochemical process, resulting in increased resistances. To address this issue, it is proposed the use of effective electrolyte additives, the combination of lithium bis(fluoromethanesulfonyl)imide (LiFSI) and lithium difluorophosphate (LiPO 2 F 2 ). LiFSI allowed for the stable cycling of the SiO x anode by forming LiF-based solid–electrolyte interphases. Meanwhile, LiPO 2 F 2 effectively suppressed undesirable LiFSI-induced corrosion reactions at the cathode also by forming stable cathode–electrolyte interphases on the surface of the Al current collector. Consequently, the cell cycled with LiFSI/LiPO 2 F 2 -containing electrolyte exhibited improved cycling retention (94.6%). ● LiFSI makes robust SEI layer on the SiO x anode via electrochemical reaction. ● LiFSI-derived artificial SEI layer suppresses pulverization of SiO x anode materials. ● Al-corrosion at cathode triggered by LiFSI can be stabilized by employing LiPO 2 F 2. ● LiFSI/LiPO 2 F 2 -combined additives improve cycling performance of SiO x /NCM cells. ● Role of each additive is analyzed in terms of chemical/electrochemical reactivity.