2,4,6-Tris(4-fluorophenyl)cyclo-boroxine as an Electrolytes Additive to Form Ultrathin CEI Interfacial Membrane for Improved High-Voltage LiNi_0.8Co_0.1Mn_0.1O₂ Lithium-Ion Batteries

Increasing the cutoff voltage for charging lithium batteries can increase the capacity density of lithium-ion batteries. Still, it is also accompanied by some adverse effects, including electrode material corrosion and electrolyte loss. To mitigate these adverse effects, this article reports on a high-voltage catholyte additive, 2,4,6-tris(4-fluorophenyl)cyclo-boroxine (PFTB). Calculation demonstrates that the HOMO energy level of PFTB is lower than that of typical solvents. Consequently, PFTB can decompose selectively to generate a robust and conductive protective CEI membrane. This reduces the occurrence of interfacial side reactions and thus protects the electrode material’s structural integrity. The outcomes of extended cyclical assessments demonstrate that the capacity retention rates are 83.7% (4.2 V), 89.0% (4.3 V), 80.4% (4.4 V), and 81.8% (4.5 V), respectively, when 1.0 wt % PFTB is incorporated into the standard electrolyte. The results of the physical characterization demonstrate that PFTB undergoes preferential decomposition on the cathode, forming a CEI membrane rich in F and B elements. These elements can effectively enhance the conductivity and stability of the CEI membrane. Therefore, adding PFTB to the electrolyte as an additive provides an economical and effective method for studying high-energy lithium batteries.