Benzoic Anhydride as a Bifunctional Electrolyte Additive for Hydrogen Fluoride Capture and Robust Film Construction over High‐Voltage Li‐Ion Batteries

Abstract

High-voltage LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)-based Li-ion batteries (LIBs) with enhanced performance can be achieved by properly tailoring the electrolyte systems. Benzoic anhydride (BA) was proposed here as a promising bifunctional electrolyte additive that can not only construct a robust cathode-electrolyte interface (CEI) film on the electrode surface but also capture HF/H 2 O in the electrolyte effectively. Compared to the cell without the BA additive, the capacity of Li/NCM811 half-cell with 1.0 wt % BA was increased from 128.5 to 149.6 mAh g À 1 after 200 cycles at 1 C between 3.0 and 4.3 V. Even at a higher cut-off voltage of 4.5 V, the BA-containing Li/NCM811 half-cell delivered a capacity retention of 69 % after 200 cycles, much higher than that of the half-cell without the additive (56 %). Both theoretical calculation and experimental results verified that the BA additive could be preferentially oxidized to form a stable interface film with high conductivity that protected the NCM811 cathode and suppressed the decomposition of the electrolyte.

Uracil-based additives for enabling robust interphases of high-voltage Li-ion batteries at elevated temperature by substituent effects

“…41 Although a proper LiF content is beneficial for improving the interfacial behavior, excess of the component in the SEI layer would lead to an adverse effect on the increase of the resistance. 12,42 The peak intensity of LiF on the cathode cycled in the UC-containing electrolyte was lower than that in the TUC-containing electrolyte. Combined with the previously mentioned EIS data, the results show the advantages of UC for electrolyte protection and low-resistance SEI construction.…”

“…6d. The high discharge capacities of the UC-containing cells at a large current density (Z3C) were due to the stable SEI films with a high ionic conductivity which effectively suppressed the interfacial parasitic reaction, 12,19 and the TUC-containing cell performance was opposite to this. This outcome was consistent with the results of the longcycling performance.…”

“…The unit containing -N can also cause a series of ring-opening polymerizations of EC, which were similar to the -O effect on EC found in previously reported work. 12,27 Meanwhile, the -C + units can react with protonic acid to remove HF and H 2 O in an electrolyte by a nucleophilic reaction and a Lewis acid-base reaction. 51 Then, the chemical intermediates formed, which contained -CQC-units could induce a chain of polymeric reactions for building cathodic SEI films, which were like the reactions of the anode, except that the desulfurization did not occur during the long-term cycling under high-voltage and high temperature due to the S signals found to exist in XPS and TEM-EDS results (see Fig.…”

“…[6][7][8] However, the solid electrolyte interphase (SEI) on the surfaces of electrodes, which originally play an important role in interfacial protective layers, is continuously damaged and regrows at high potentials during the chargedischarge cycling. As a result, the active materials in the cathodes or anodes are consumed by hydrogen fluoride the which is produced by the decomposition of LiPF 6 , [9][10][11][12] leading to the rapid decline of the battery performance. Therefore, it is necessary to enable robust interphases at the electrode-electrolyte interfaces for stabilizing the electrode architectures to achieve the long-term cycle performance of high-voltage LIBs.…”

Propanediol Cyclic Sulfate as An Electrolyte Additive to Improve the Cyclic Performance of LiNi0.6Co0.1Mn0.3O2/Graphite Pouch‐Cell at High Voltage

“…Even compared with other NCM cathodes modified by additives, the battery with PCS in the electrolyte exhibits considerable cycle performance at 4.5 V cutoff voltage (Figure 3c and Table S1). [9,21,[37][38][39] The rate capability of NCM613/Li and graphite/Li cells are exhibited in Figure 3d and Figure 3g, respectively. The addition of PCS significantly increases the discharge capacity of the cell at higher current densities, probably because PCS forms a thin and dense interfacial film on the electrode surface, which is more favorable for the insertion and extraction of Li + .…”