The Effect of Trimethoxyboroxine on Some Positive Electrodes for Li-Ion Batteries

Abstract

The effects of trimethoxyboroxine (TMOBX) on the electrochemical properties of some positive electrode materials for Li-ion batteries were studied. LiCoO2 (LCO), Li(Ni1/3Mn1/3Co1/3)O2 (NMC) and Li(Ni0.8Co0.15Al0.05)O2 (NCA) were chosen for study. Positive half cells containing different concentrations of TMOBX were studied using storage tests and dQ/dV analysis. These results suggest that TMOBX increases the rate of electrolyte oxidation and/or shuttle-type reactions at the positive electrode, especially at 60°C, but that there is no dramatic oxidation of TMOBX itself during the first cycles. NCA/NCA symmetric cells with different concentrations of TMOBX were constructed and tested. Capacity retention in symmetric NCA/NCA cells with small concentrations of TMOBX (0.3% and 1%) was equivalent to cells without TMOBX. Electrochemical impedance spectroscopy (EIS) tests showed that adding TMOBX decreased cell impedance when the concentration of TMOBX was no more than 1%. These results suggest TMOBX is a useful impedance reducing additive for Li-ion cells if it is incorporated at low concentration, such as 0.3%.

Electrolytes and Interphases in Li-Ion Batteries and Beyond

“…Finally, besides their interphasial properties on graphitic anode, , boroxine compounds were also explored as cathode additives. − Horino et al studied a series of trialkoxy boroxines (Table ) and found that, when the substituent was iso-propyl, the anodic stability of carbonate electrolytes improved up to 5.0 V on Li 2 Mn 2 O 4 surface over the baseline electrolyte (Figure a) . Of course, as a 4.0 V class cathode, Li 2 Mn 2 O 4 does not have any redox activity in the vicinity of 5.0 V, and it was only used here as a more reliable working electrode than nonporous electrodes such as Pt or glassy carbon.…”

Molecular-Scale Interfacial Model for Predicting Electrode Performance in Rechargeable Batteries

“…Solid–electrolyte interphase (SEI) formation on the electrode interface has become an omnipotent explanation for the improved performance of electrodes in rechargeable batteries. − There is a consensus that the SEI is formed by electrolyte decomposition in the initial cycles and thus reduces the contact area of the electrode and electrolyte for mitigated side reactions. − This belief is particularly popular regarding the graphite anode in commercial lithium-ion batteries (LIBs). − This is because SEI formation is considered to be a positive effect that improves the first Coulombic efficiency (i.e., mitigating electrolyte decomposition) and enhances the compatibility of graphite with electrolyte, achieving highly reversible Li + (de)­intercalation. − This SEI formation is additionally believed to suppress Li + –solvent co-insertion into graphite in propylene carbonate (PC)-based electrolyte, thereby avoiding the well-known graphite exfoliation process. − In addition, the positive effect of SEI for the improved stability of the cathode (e.g., LiNi 1– x – y Co x Mn y O 2 , NCM) has also been widely reported. − …”

High‐Voltage Layered Ternary Oxide Cathode Materials: Failure Mechanisms and Modification Methods†

“…Electrolyte additives consisting of sulfur ( e.g ., prop‐1‐ene‐1,3‐ sulton (PES) and methylene methane disulfonate (MMDS), divinyl sulfone (DVS)), [ 182‐185 ] phosphorus ( e.g ., tris(trimethylsilyl)phosphite (TMSP or TTSPi)), [ 182‐184,186 ] nitrogen ( e.g ., succinonitrile (SN)) [ 186 ] and boron ( e.g ., trimethoxyboroxine (TMOBX), tris‐(trimethylsilyl)borate (TMSB)) [ 187‐190 ] functional groups used in combination have been reported. Figure 17 systematically investigated and compared the effects of electrolyte additives singly or in combination on LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111)/graphite pouch cells in terms of charge transfer resistance, charge slippage, coulombic efficiency and gas produced in formation (represented by “figure of merits”).…”