Role of Electrolyte Oxidation and Difluorophosphoric Acid Generation in Crossover and Capacity Fade in Lithium Ion Batteries

Poor cycling performance for many high voltage lithium ion batteries (LIB) has been attributed to damage of the anode solid electrolyte interphase (SEI) resulting from crossover reactions. Transition-metal proposed as a primary source SEI and capacity loss, especially high-voltage spinel cathodes. However, deposition transition metals on may not be degradation. This investigation focuses oxidative decomposition LiPF6 in ethylene carbonate (EC)-based electrolytes generate acidic species which subsequently cross over degrade components. The generation strong acid, difluorophosphoric acid (F2PO2H), quantified both graphite || LiNi0.5Mn1.5O4 LiMn2O4 cells. There is correlation between concentration F2PO2H, degradation, loss