Dioxazolone and Nitrile Sulfite Electrolyte Additives for Lithium-Ion Cells

Electrolyte additives are used in lithium-ion cells to achieve higher energy densities and longer lifetimes for electric vehicle and grid storage applications. This work tests a recently developed electrolyte additive, MDO (3-methyl-1,4,2-dioxazol-5-one) and introduces two new additives, PDO (3-phenyl-1,4,2-dioxazol-5-one) and BS (benzonitrile sulfite, 5-phenyl-1,3,2,4-dioxathiazole 2-oxide). The cell formation, high temperature storage and long-term cycling performance of lithium-ion NMC/graphite pouch cells prepared with these additives and binary blends thereof are presented. Differential capacity results indicate that MDO and PDO form passive solid-electrolyte interphase layers on the graphite electrode during cell formation, whereas BS does not. It is demonstrated that PDO is a highly promising new additive, especially when used as a binary blend with lithium difluorophosphate or ethylene sulfate. Future work is encouraged to explore the interactions between these additives and develop optimized solution chemistries, for example by adjusting the ratio of primary and secondary additives or through introducing ternary blends.