Synergetic Effects of Inorganic Components in Solid Electrolyte Interphase on High Cycle Efficiency of Lithium Ion Batteries

The solid electrolyte interphase (SEI), a passivation layer formed on electrodes, is critical to battery performance and durability. The inorganic components in SEI, including lithium carbonate (Li₂CO₃) and lithium fluoride (LiF), provide both mechanical and chemical protection, meanwhile control lithium ion transport. Although both Li₂CO₃ and LiF have relatively low ionic conductivity, we found, surprisingly, that the contact between Li₂CO₃ and LiF can promote space charge accumulation along their interfaces, which generates a higher ionic carrier concentration and significantly improves lithium ion transport and reduces electron leakage. The synergetic effect of the two inorganic components leads to high current efficiency and long cycle stability.