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.

Abstract

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 LiNi0.8Co0.1Mn0.1O2 (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.