Fluoroethylene carbonate (FEC) and lithium difluorophosphate (LiPO2F2) are evaluated as hybrid functional additives to improve the electrochemical performance of SiC-based lithium-ion batteries. When added to the electrolyte, FEC + LiPO2F2 significantly enhance the performance of SiC/Li cells. The capacity retention increases from 28.5% to 76.2% after 200 cycles. The effects of FEC + LiPO2F2 are characterized by charge–discharge testing, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Combining the results of these analyses reveals that hybrid functional additives are beneficial for forming a uniform and thinner solid–electrolyte interface film on the SiC surface. The solid–electrolyte interface film derived from FEC + LiPO2F2 greatly inhibits particle pulverization and electrolyte decomposition, which play an important role in the performance of SiC-based cells.