Synergy Effect of Trimethyl Borate on Protecting High-Voltage Cathode Materials in Dual-Additive Electrolytes

Abstract

The lack of electrolyte that is stable under high potentials hinders the application of high-voltage cathode materials for lithium batteries; the introduction of electrolyte additives is clearly the most effective solution to address this issue. Herein, we investigated the synergistic effects of trimethyl borate (TMB) in two dual-additive electrolytes on protecting the LiNi0.8Co0.1Mn0.1O2 and LiCoO2 cathode materials under high potentials. The interactions of TMB with fluoroethylene carbonate and the catalysis of the decomposition product of TMB to tetramethylene sulfone lower the onset oxidation potential of these additives and are beneficial in forming a stable cathode electrolyte interphase film on the cathode materials. This work sheds light on another way of electrolyte designing for high-voltage cathode materials.

Perspectives on Improving the Safety and Sustainability of High Voltage Lithium‐Ion Batteries Through the Electrolyte and Separator Region

“…In recent years, multifunctional additives have been increasingly more popular. These CEIforming additives typically contain functional groups such as isocyanate (NCO), [97][98][99][100] silane derivatives (SiO), [101][102][103][104][105][106] sultones (SO), [88,[107][108][109][110][111] borates (BO), [112][113][114][115] or phosphorouscontaining groups, [116][117][118][119][120] which are capable of scavenging HF. Many of these CEI-forming additives can also promote SEI formation on the anode, serving multiple important functions in the cell.…”

“…[ 108 ] Liu et al took dual‐additive electrolytes a step further by utilizing trimethyl borate to improve the performance of other additives, i.e., by promoting the oxidation of tetramethylene sulfone (TMS) to improve the CEI stability or through interaction with FEC to lower the onset oxidation potential. [ 115 ] Zhu et al reported a novel phosphate‐containing additive (diethyl(thiophen‐2‐ylmethyl)phosphate) that dramatically improved the capacity retention of an HV LiNi 0.5 Mn 1.5 O 4 battery. [ 120 ] This additive not only stabilized the CEI, but it also served to improve the thermal stability of the electrolyte and improve the resistance to combustion.…”

Enhanced Interfacial Stability of a LiNi0.9Co0.05Mn0.05O2 Cathode by a Diboron Additive

“…29 Nonetheless, the optimized amount of 10% TEB (added into baseline electrolyte) would be too high to be applied in mass production. Beyond that, a trimethyl borate (TMB) additive together with tetramethylene sulfone (TMS) as synergistic electrolyte components was introduced to improve the electrochemical performance of the LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode at 4.5 V. 30 Considering the unique features of a boron-type additive, here, we propose, for the first time, a novel boron-containing additive, 5,5,5′,5′-tetramethyl-2,2′-bi-1,3,2-dioxaborinane (short as TBDB) (molecular structure is displayed in Figure 1). It is demonstrated that the TBDB additive could effectively stabilize the interface of single-crystal Ni-rich cathode Li[Ni 0.9 Co 0.05 Mn 0.05 ]O 2 (NCM90), and pronouncedly improve the electrochemical performance even with a limited amount (0.3 wt %), signifying an efficient electrolyte additive.…”

“…Nonetheless, the optimized amount of 10% TEB (added into baseline electrolyte) would be too high to be applied in mass production. Beyond that, a trimethyl borate (TMB) additive together with tetramethylene sulfone (TMS) as synergistic electrolyte components was introduced to improve the electrochemical performance of the LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode at 4.5 V …”

High‐Voltage Electrolyte Chemistry for Lithium Batteries

“…Liu et al proposed two dual‐additive solutions, using the synergistic effects of trimethyl borate (TMB) with tetramethylene sulfone (TMS) and FEC, respectively, to protect the NCM811 cathode and LCO cathode at high potential. [ 74 ] The difference between this work and other double‐additive methods is that, whereas other double‐additive methods basically have two additives acting independently, here there is an interaction between the two additives. When TMB and TMS exist in the electrolyte at the same time, the decomposition products of TMB can catalyze the oxidation of TMS and reduce the oxidation potential of TMS.…”