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.

Impact of Trace Nickel in the Electrolyte on the Electrochemistry of Positive Electrodes for Lithium-Ion Batteries

“…Clearly, the cycling performance of the cells with electrolytes exhibiting lower Ni concentrations is improved compared to the case of saturated solutions, obviously due to the reduced Ni 2+ concentration 29 and possible improvement of the CEI properties. 30 There is one point not discussed yet, namely that some Ni ions will be deposited on the negative lithium counter electrode and, consequently, the Ni concentration in the electrolyte will decrease gradually during cycling, below the nominal value. The observed clear effects on the oxide cycling allow the conclusion that there were still enough Ni ions in the solution, which is also supported by the fact that there are strong differences between the electrochemistry of NMC811 electrodes in nominally saturated solutions and the solutions with nominally 20 μmol L −1 of impurities.…”

Surface cobaltization for boosted kinetics and excellent stability of nickel-rich layered cathodes

“…In sharp contrast, NM64 exhibits a pronounced discharge curve and lower reversible capacity, and NCM622 exhibits rapid capacity degradation. Figure 5c and TableS4 illustrate cycle retention rate of Co-NM64 at high voltages, demonstrating its competitiveness among other typical ternary cathode materials [60][61][62][63][64][65][66][67][68]. To understand the intrinsic reason for the electrochemical behavior of the three materials in the full cell, HRTEM was performed to observe the cathode surface after 50 cycles.…”

Challenges and opportunities using Ni-rich layered oxide cathodes in Li-ion rechargeable batteries: the case of nickel cobalt manganese oxides

“…Dual coating is considered an effective approach for the improvement of the electrode/electrolyte interface. 254,255 It not only improves the discharge capacity but also increases the cyclic performance. 256 It involves applying two separate layers of protective materials onto the surface of the cathode particles.…”