Blended Salt Electrolyte Design for Enhanced NMC811||Graphite Cell Performance

Abstract

The high energy density, nickel‐rich layered cathode material LiNi0.8Mn0.1Co0.1O2 (NMC811) is recognized as a promising candidate for next‐generation battery chemistries. However, due to their structural and interfacial instability, nickel‐rich NMC cathodes still face a number of challenges in practical application. For this reason, the design and development of novel electrolyte formulations, able to stabilize the nickel‐rich cathode|electrolyte interface, are highly demanded. In this work, a novel electrolyte is developed using lithium (difluoromethanesulfonyl) (trifluoromethanesulfonyl)imide (LiDFTFSI) and lithium hexafluorophosphate (LiPF6) as salt blend in an organic carbonate‐solvent based solvent mixture. The presence of LiDFTFSI notably enhances the electrochemical performance of the resulting NMC811||graphite cells. Further advancement of the considered cell chemistry is achieved by introducing the well‐known functional electrolyte additive vinylene carbonate (VC), which was found to feature a synergistic effect with LiDFTFSI. The formation of a homogenous, effective, and robust solid electrolyte interphase (SEI) as well as cathode electrolyte interphase (CEI) on the corresponding electrodes resulted in superior electrochemical performance.