Tri-anion solvation structure electrolyte improves the electrochemical performance of Li||LiNi0.8Co0.1Mn0.1O2 batteries.

ABSTRACT

Li||LiNi0.8Co0.1Mn0.1O2 batteries,which consist of lithium  metal anode (LMA) matched with NCM811 cathode, have an energy density more than twice that of lithium ion battery (LIB). However, the unstable electrode/electrolyte interface still hinders its practical application.Ether electrolytes show promise in improving the stability of LMA and NCM811 cathodes.However, a robust and stable electrode/electrolyte interface in Li||NCM811 batteries cannot be easily and efficiently achieved with most of the ether electrolytes reported in present studies. Herein, we present a straightforward and efficient tri-anion synergistic strategy to overcome this bottleneck. The addition of ClO4- and NO3- anions to LiFSI-based ether electrolytes forms a unique solvation structure with tri-anion (FSI-/ClO4-/NO3-) participation (LB511).This structure not only enhances the electrochemical window of the ether electrolytes but also achieves a stable Li||NCM811 batteries interface.The interaction between electrode and electrolyte is suppressed and an inorganic-rich (LiF/Li3N/LiCl) SEI/CEI layer is formed. Meanwhile, the coordination structure in the LB511 electrolyte increases the overpotential for Li deposition, resulting in a uniform and dense layer of deposition.Therefore, the Li||Cu cells using the LB511 electrolyte have an average CE of 99.6%.The Li||NCM811 batteries was cycled stably for 250 cycles with a capacity retention of 81% in the LB511 electrolyte (N/P = 2.5, 0.5 C).