Surface Work Function-Induced Thermally Vulnerable Solid Electrolyte Interphase Formation on the Negative Electrode for Lithium-Ion Batteries

The chemical composition significantly affects the inherent electrical surface properties of the graphite and SiO electrodes, which further, significantly alters the thermal stability of solid electrolyte interphase (SEI) on the negative electrodes. Because the work function of the graphite edge plane is lower than that of the SiO2-dominant SiO electrode when the electrode is initially lithiated, charge transfer toward the electrolyte is hindered by the high work function of SiO2. Given the increased solubility of the SEI film on SiO, which makes it vulnerable to self-discharge at higher temperatures than graphite, SiO electrodes exhibit inferior electrochemical performance at high temperatures compared to graphite electrodes. To enhance the performance of SiO electrodes at high temperatures, it is essential to modify the surface work function of the Si-based electrodes or the lowest unoccupied molecular orbital energy level of the electrolyte additive. Intrinsic surface electric conductivity significantly influences thermal stability of the negative electrode for lithium-ion batteries by distinct solid electrolyte interphase (SEI) formation. While high work function demonstrating SiO2 on silicon electrode inhibits charge transfer across the surface of electrode and forms organic-based thermally vulnerable SEI, graphite electrode exhibits inorganic-based thermally durable SEI due to low work function of electrode surface.image