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

Abstract

The high energy density, nickel‐rich layered cathode material LiNi 0.8 Mn 0.1 Co 0.1 O 2 (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 (LiPF 6 ) 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.