Author: Karina Asheim
Title: LiFSI as electrolyte salt for silicon anodes and NMC cathodes
Affiliation: Norwegian University of Science and Technology
Silicon is a promising high capacity anode material for Li-ion batteries. The challenge is electrode degradation and continuous solid-electrolyte interphase (SEI) growth due to volume expansion during lithiation. A stable and strong SEI is then crucial for the performance. The commercially used LiPF6 salt is susceptible to hydrolysis, forming HF which etches the SiO2 layer. An alternative salt, lithium bis(fluorosulfonyl)imide (LiFSI), has been found to improve performance of Si electrodes compared to when using LiPF6. In this work, LiFSI is evaluated as electrolyte salt for Si anode and NMC cathode in half-cell configuration. Through post mortem characterization, involving cross sectional analysis, using FIB in combination with SEM, TEM to evaluate crystallinity of particles and acquire element maps of the SEI, and XPS of the electrode surface to determine which oxidation state of elements are present, the improved performance of Si when using LiFSI is attempted explained.