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

Silicon oxide (SiOx) has attracted considerable attention as an advanced anode material; however, SiOx 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 (LiPO2F2). LiFSI allowed for the stable cycling of the SiOx anode by forming LiF-based solid-electrolyte interphases. Meanwhile, LiPO2F2 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/LiPO2F2-containing electrolyte exhibited improved cycling retention (94.6%).