Building stable solid electrolyte interphases (SEI) for microsized silicon anode and 5V-class cathode with salt engineered nonflammable phosphate-based lithium-ion battery electrolyte

Abstract Silicon is one of the most promising anode materials for lithium-ion batteries due to its low cost, high energy density and abundant resources. However, fast capacity decay caused by the huge volume changes and the unstable solid electrolyte interface (SEI) limits its commercial applications. In this work, the effects of lithium hexafluorophosphate (LiPF6) and lithium difluoroacetate borate (LiDFOB) on the performance of microsized silicon anode were compared using nonflammable pure trimethyl phosphate (TMP) as the solvent. It is found that microsized silicon anode with 1 M LiDFOB/TMP electrolyte can produce a more stable solid electrolyte interface (SEI), which effectively prevents capacity loss. The capacity has a high retention even after 100 cycles with nearly 100% coulombic efficiency. Moreover, 5V-class cathode shows a better cycling stability with LiDFOB salt. This work may provide a novel direction for expanding the fields of lithium-ion batteries anode which has high safety and high energy density.