Tri-Anion Solvation Structure Electrolyte Improves the Electrochemical Performance of Li||LiNi0.8Co0.1Mn0.1O2 Batteries

Abstract

Li||LiNi_0.8Co_0.1Mn_0.1O₂ 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 Li 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).