Synergistic Effect of Dual-Anion Additives Promotes the Fast Dynamics and High-Voltage Performance of Ni-Rich Lithium-Ion Batteries by Regulating the Electrode/Electrolyte Interface

Combining the Ni-rich layered cathode (Ni ≥ 80%) with high operating voltage is considered as a feasible solution to achieve high-energy lithium-ion batteries (LIBs). However, the working voltage is limited in practical applications due to the poor interface stability in traditional carbonate electrolytes. Herein, LiBF₄ and LiNO₃ are added as film-forming additives and 1.0 M LiPF₆ in SL/FEC/EMC with 0.5 wt % LiBF₄-LiNO₃ (HVE) is obtained. A uniform and inorganic-rich cathode electrolyte interphase (CEI) as well as a dense and Li₃N-LiF-rich solid electrolyte interphase (SEI) could be in situ generated on LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) and graphite (Gr) electrode in HVE, respectively. The robust interface film with electronic insulation and ionic conductivity effectively stabilizes the NCM811/Gr-electrolyte interfaces and improves the Li⁺ diffusion kinetics, enabling the high-load NCM811-Gr to maintain 85.2% capacity (∼180 mA h g^-1) after 300 cycles under 4.4 V. Besides, the 4.2 V NCM811-Gr retains 90.4% of the initial capacity after 200 cycles at 2 C (∼6 mA h cm^-2). Compared with the traditional carbonate electrolyte (LB301), HVE has obvious advantages in terms of high-voltage and fast dynamics performance. Especially, good thermal stability and economy make HVE a promising electrolyte for commercial high-energy LIBs.