The Roles of Sulfur-Containing Additives and Their Working Mechanism on the Temperature-Dependent Performances of Li-Ion Batteries

In this work, we investigate the effects of three different sulfur-containing additives, particularly ethylene sulfate (or 1,3,2-dioxathiolane-2,2-dioxide (DTD)), 1,3-propane sultone (1,3-PS) and ethylene sulfite (ES) on the cycling and high temperature storage performance of high-voltage LiCoO2 and artificial graphite electrodes. These additives process the different sulfur-containing functional groups and exhibit different performance, so that the impacts of changes to the functional group on the electrochemical behavior are interesting to study. Our aim is to understand the relationships between functional groups of these kinds of additives and their roles in improvement of the electrochemical and storage performance of the electrodes. The results clearly indicate that three additives are involved in film-formation on the surface of LiCoO2 and graphite. Among them, CEI (cathode electrolyte interphase) films formed by DTD and 1,3-PS covered on cathode are thin and stable, thus they can cause a significant improvement of cycle performance in high voltage LiCoO2. Also, the SEI film happened in anode of graphite formed by DTD can deliver a good performance at low temperature. On the contrary, the CEI or solid electrolyte interphase (SEI) films formed by ES are not dense and unstable. Therefore it is detrimental to the cycle performance at room, low and elevated temperature.