JP2023062096A - Novel battery system based on lithium difluorophosphate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte capable of improving the performance and life of Li ion batteries while reducing costs over other systems that rely on more additives.

SOLUTION: A nonaqueous electrolyte for a lithium ion battery includes a lithium salt, a first nonaqueous solvent, and an additive mixture comprising a first operative additive of lithium difluorophosphate and a second operative additive of either fluoro ethylene carbonate or vinylene carbonate. A lithium ion battery includes a negative electrode, a positive electrode comprising NMC with micrometer-scale particles, a nonaqueous electrolyte having lithium ions dissolved in a first nonaqueous solvent, and an additive mixture having a first operative additive of either fluoro ethylene carbonate or vinylene carbonate and a second operative additive of either 1,3,2-dioxathiolane-2,2-dioxide, another sulfur-containing additive, or lithium difluorophosphate.

SELECTED DRAWING: Figure 46D

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present disclosure relates to rechargeable battery systems and, more particularly, to the chemistries of such systems, including active electrolyte additives and electrodes for improving the properties of rechargeable lithium-ion battery systems.

Rechargeable batteries are an integral component of energy storage systems for electric vehicles and grid storage (eg, as part of microgrids, for backup power during power outages, etc.). Li-ion based batteries are a common type of rechargeable battery.

Electrolyte additives have been shown to be effective and improve the life and performance of Li-ion based batteries. For example, in Non-Patent Document 1, five proprietary, undisclosed electrolyte additives are shown to extend cycle life compared to electrolytes with only one or no additives. Other studies have focused on performance gains from electrolyte systems containing three or four additives, as described in US Pat. However, researchers typically do not understand the interactions between different additives that allow them to act synergistically with electrolytes and certain positive and negative electrodes. Therefore, the composition of additive formulations for a particular system is often based on trial and error and cannot be predicted in advance.

Previous studies have not identified a two-additive electrolyte system that could be incorporated into a lithium-ion battery system to create a robust system with sufficient properties for grid or automotive applications. As discussed in US Pat. No. 5,200,000, two-additive systems studied (e.g., 2% VC + 1% allyl methanesulfonate and 2% PES + 1% TTSPi) typically performed worse than three- or four-additive electrolyte systems. (See, for example, Tables 1 and 2 of Patent Document 1). US Pat. No. 5,300,003 discloses a third compound, often tris(trimethylsilyl) phosphate (TTSP) or tris(trimethylsilyl ) (TTSPi) was necessary (see, for example, paragraph 72 of US Pat. However, since additives can be expensive and difficult to include in Li-ion batteries on a manufacturing scale, simpler yet effective battery systems containing fewer additives are needed.

The present disclosure is directed to novel battery systems with less effective electrolyte additives that can be used in different energy storage applications such as vehicles and grid storage. More specifically, the present disclosure includes a two-additive electrolyte system that improves the performance and life of Li-ion batteries while reducing cost over other systems that rely on more additives. The present disclosure also discloses effective positive and negative electrodes that cooperate with the disclosed two-additive electrolyte system to provide further system enhancements.

The disclosed two-effective additive electrolyte system comprises: 1) 1,3,2-dioxathiolane-2,2-dioxide (DTD, also known as ethylene sulfate) or another sulfur-containing additive (methylene methane disulfate , trimethylene sulfate, 3-hydroxypropanesulfonic acid gamma sultone, glycol sulfite, or another sulfur-containing additive); 2) fluorocarbon in combination with DTD or another sulfur-containing additive; ethylene carbonate (FEC), and 3) prop-1-ene-1,3-sultone (PES) in combination with DTD or another sulfur-containing additive. Furthermore, since VC and FEC provide similar improvements (and are believed to perform similarly), a mixture of VC and FEC may be considered a single effective electrolyte. Thus, another disclosed two-effective additive electrolyte system includes a mixture of VC and FEC in combination with DTD or another sulfur-containing additive. When used as part of a larger battery system (including electrolyte, electrolyte solvent, positive electrode, and negative electrode), these dual additive electrolyte systems provide desirable properties for energy storage applications, including vehicle and grid applications. .

More specifically, lithium nickel manganese cobalt oxide (NMC) positive electrodes, graphite negative electrodes, lithium salts dissolved in organic or non-aqueous solvents that may include methyl acetate (MA), and battery systems with desirable properties for different applications. Two additives to form. The electrolyte solvent can be the following solvents, alone or in combination: ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl acetate, propylene carbonate, dimethyl carbonate, diethyl carbonate, another carbonate solvent (cyclic or acyclic formula), another organic solvent, and/or another non-aqueous solvent. The solvent is present at a higher concentration than the additive, usually greater than 6% by weight. Solvents are combined with the two disclosed additive pairs (VC and DTD, FEC and DTD, a mixture of VC and FEC and DTD, or another combination) to form battery systems with desirable properties for different applications. may The positive electrode may be coated with _a material such as aluminum oxide ( _Al2O3 ), titanium dioxide ( _TiO2 ), or another coating. Additionally, as a cost savings, the negative electrode may be formed from natural graphite, but depending on the price structure, synthetic graphite is cheaper than natural graphite in certain cases.

The disclosure herein is supported by experimental data demonstrating the symbiotic nature of the two-additive electrolyte system and selected electrodes. An exemplary battery system includes two additives (eg, FEC, VC, or PES and DTD or another sulfur-based additive), a graphite anode (naturally occurring graphite or man-made synthetic graphite), an NMC cathode, A lithium electrolyte (eg, formed from a lithium salt such as lithium hexafluorophosphate of chemical composition _LiPF6 ), and an organic or non-aqueous solvent. A lithium ion battery comprises a negative electrode, a positive electrode comprising NMC having micrometer-scale particles, lithium ions dissolved in a first non-aqueous solvent, and a first active additive of either fluoroethylene carbonate or vinylene carbonate and a second active additive of either 1,3,2-dioxathiolane-2,2-dioxide, another sulfur-containing additive, or lithium difluorophosphate. can contain.

1 is a schematic diagram of a vehicle including a power storage system; FIG.

1 is a schematic diagram of an exemplary electrical storage system; FIG.

1 is a schematic diagram of a lithium-ion battery-cell system; FIG.

Figures 4A-4J show typical experimental data collected during ultra-precise charging experiments of battery systems with different electrolyte compositions.

FIG. 3 shows time-normalized coulombic inefficiency per hour (CIE/h) versus number of cycles for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD.

FIG. 2 shows coulombic efficiency (CE) versus number of cycles for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD.

FIG. 4 shows end-of-charge capacity plotted against cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD.

FIG. 3 shows discharge capacity versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD.

FIG. 3 shows the change in open circuit voltage versus number of cycles for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD.

FIG. 3 shows time-normalized coulombic inefficiency per hour (CIE/h) versus number of cycles for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD.

FIG. 10 shows coulombic efficiency (CE) versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD.

FIG. 3 shows end-of-charge capacity plotted against cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD.

FIG. 3 shows discharge capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD.

FIG. 3 shows the difference between the average charging voltage and the average charging voltage (delta V) versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD.

FIGS. 5A-5C show the average of the last three cycles of the data shown in FIG. It shows lower coulombic inefficiency per hour and lower fragment slippage per hour.

Figure 5 shows the average coulombic inefficiency per hour for the last three cycles of data generated during the experiment shown in Figure 4;

Figure 5 shows the average fragment slip of the last three cycles of the data generated during the experiment shown in Figure 4;

Figure 5 shows the average fractional fade of the last three cycles of the data generated during the experiment shown in Figure 4;

6A-6F show typical experimental data studying long-term cycling at 40° C., C/3CCCV, demonstrating the benefits of including DTD as an additive to electrolyte systems containing VC or FEC.

Figure 2 shows capacity versus number of cycles for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.2V. is.

Normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0 V and 4.2 V. FIG. 4 is a diagram showing;

Voltage hysteresis (average charging voltage and FIG. 10 is a diagram showing the difference from the average charging voltage) vs. the number of cycles.

Figure 2 shows capacity versus number of cycles for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.2V. is.

Normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0 V and 4.2 V. FIG. 4 is a diagram showing;

Voltage hysteresis (average charging voltage and FIG. 10 is a diagram showing the difference from the average charging voltage) vs. the number of cycles.

Figures 7A-7F show typical experimental data studying long-term cycling at C/3CCCV at 20°C, demonstrating the benefits of including DTD as an additive to electrolyte systems containing VC or FEC.

Figure 2 shows capacity versus number of cycles for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.3V. is.

Normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0 V and 4.3 V. FIG. 4 is a diagram showing;

Voltage hysteresis (average charging voltage and FIG. 10 is a diagram showing the difference from the average charging voltage) vs. the number of cycles.

Figure 2 shows capacity versus number of cycles for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.3V. is.

Normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0 V and 4.3 V. FIG. 4 is a diagram showing;

Voltage hysteresis (average charging voltage and FIG. 10 is a diagram showing the difference from the average charging voltage) vs. the number of cycles.

Figures 8A-8I show exemplary empirical data collected during cycling experiments of electrolyte composition according to certain embodiments of the present disclosure.

2% FEC, 1% FEC + 1% DTD, cycling between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 4 shows peak capacity versus cycle number for electrolyte systems containing 2% FEC+1% DTD, 1% FEC+1% MMDS, and 2% FEC+1% MMDS.

2% FEC, 1% FEC + 1% DTD, cycling between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 10 shows normalized capacity versus cycle number for electrolyte systems containing 2% FEC+1% DTD, 1% FEC+1% MMDS, and 2% FEC+1% MMDS.

2% FEC, 1% FEC + 1% DTD, cycling between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 3 shows voltage hysteresis (difference between average charging voltage and average charging voltage) for electrolyte systems including 2% FEC+1% DTD, 1% FEC+1% MMDS, and 2% FEC+1% MMDS.

2% VC, 1% VC + 1% DTD, cycling between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 4 shows peak capacity versus cycle number for electrolyte systems containing 2% VC+1% DTD, 1% VC+1% MMDS, and 2% VC+1% MMDS.

2% VC, 1% VC + 1% DTD, cycling between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 3 shows normalized capacity versus cycle number for electrolyte systems containing 2% VC+1% DTD, 1% VC+1% MMDS, and 2% VC+1% MMDS.

2% FEC, 1% VC+1% in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate by weight, cycling between 3.0 V and 4.3 V at 40°C FIG. 3 shows voltage hysteresis (difference between average charging voltage and average charging voltage) for electrolyte systems containing DTD, 2%VC+1%DTD, 1%VC+1%MMDS, and 2%VC+1%MMDS.

2% PES, 1% PES + 1% DTD, cycled between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 4 shows peak capacity versus cycle number for electrolyte systems containing 2% PES+1% DTD, 1% PES+1% MMDS, and 2% PES+1% MMDS.

2% PES, 1% PES + 1% DTD, cycled between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 2 shows normalized capacity versus cycle number for electrolyte systems containing 2% PES+1% DTD, 1% PES+1% MMDS, and 2% PES+1% MMDS.

2% FEC, 1% PES + 1% DTD, cycled between 3.0 V and 4.3 V at 40°C in a base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; FIG. 3 shows voltage hysteresis (difference between average charging voltage and average charging voltage) for electrolyte systems including 2% PES+1% DTD, 1% PES+1% MMDS, and 2% PES+1% MMDS.

Figures 9A-9D and 9F-9I show that methyl acetate can be added to electrolyte systems containing VCs or FECs with DTDs to increase electrolyte conductivity and reduce viscosity without significantly sacrificing lifetime. , showing typical experimental data collected during several ultra-precision charging experiments. Improved conductivity and reduced viscosity are important for certain applications requiring higher charging rates.

4 is exemplary experimental data showing coulombic efficiency (CE) versus cycle number for electrolyte systems according to certain embodiments of the present disclosure;

6 is exemplary experimental data showing end-of-charge capacity plotted against cycle number for an electrolyte system according to certain embodiments of the present disclosure;

6 is exemplary experimental data showing discharge capacity versus cycle number for electrolyte systems according to certain embodiments of the present disclosure;

4 is exemplary experimental data showing the difference between the average charging voltage and the average charging voltage at open circuit voltage (delta V) versus cycle number for an electrolyte system according to certain embodiments of the present disclosure;

6 is exemplary experimental data of coulombic efficiency (CE) versus cycle number for electrolyte systems according to certain embodiments of the present disclosure;

6 is exemplary experimental data of end-of-charge capacity plotted against cycle number for an electrolyte system according to certain embodiments of the present disclosure;

6 is exemplary experimental data of discharge capacity versus cycle number for electrolyte systems according to certain embodiments of the present disclosure;

5 is exemplary experimental data of the difference between the average charging voltage and the average charging voltage (delta V) versus cycle number for an electrolyte system according to certain embodiments of the present disclosure;

Figures 10A-10C are plots summarizing the experimental data, with increasing MA content, electrolyte additives VC and FEC, both alone and in the presence of DTD, still provided acceptable performance. indicates that

FIG. 2 is a plot summarizing experimental data of time-normalized CIE as a function of MA content; FIG.

FIG. 4 is a plot summarizing experimental data of time-normalized fragment fade as a function of MA content; FIG.

FIG. 4 is a plot summarizing the time-normalized fractional charge endpoint capacity slip as a function of MA content; FIG.

Experimental data for the parasitic heat flow and the difference between the parasitic heat flow and the parasitic heat flow for cells containing 2% FEC + 0% MA as a function of voltage for different electrolyte compositions with FEC in the voltage range of 4.0 V to 4.2 V were summarized. Plot.

Experimental data for the parasitic heat flow and the difference between the parasitic heat flow and the parasitic heat flow for cells containing 2% FEC + 0% MA as a function of voltage for different electrolyte compositions with FEC in the voltage range of 4.0 V to 4.3 V were summarized. Plot. FIG. 12A shows the results from the first cycle to 4.3V. FIG. 12B shows the results of the second cycle.

Experimental data for the parasitic heat flow and the difference between the parasitic heat flow and the parasitic heat flow for cells containing 2% FEC + 0% MA as a function of voltage for different electrolyte compositions with FEC in the voltage range of 4.0 V to 4.4 V were summarized. Plot. Results are shown from the first cycle to 4.4V. Results for the second cycle are shown.

14 is a plot summarizing experimental parasitic heat flow data, including the data shown in FIGS. 11-13; FIG.

15A-15F are plots of experimental data obtained at 20° C. of capacity, normalized capacity, and voltage hysteresis (difference between average charge voltage and average charge voltage) versus cycle number for electrolyte systems containing FEC. is.

FIG. 2 is a plot of experimental data obtained at 20° C. of capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.2V. FIG.

FIG. 3 is a plot of experimental data obtained at 20° C. of normalized capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.2V.

Fig. 3 is a plot of experimental data obtained at 20°C of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing FEC cycled up to 4.2V.

FIG. 10 is a plot of experimental data obtained at 20° C. of capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V. FIG.

FIG. 2 is a plot of experimental data obtained at 20° C. of normalized capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V.

FIG. 2 is a plot of experimental data obtained at 20° C. of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V.

16A-16F are plots of experimental data obtained at 40° C. of capacity, normalized capacity, and voltage hysteresis for electrolyte systems including FEC.

FIG. 4 is a plot of experimental data obtained at 40° C. of capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.2V.

FIG. 4 is a plot of experimental data obtained at 40° C. of normalized capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.2V.

FIG. 2 is a plot of experimental data obtained at 40° C. of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing FEC cycled up to 4.2V.

FIG. 2 is a plot of experimental data obtained at 40° C. of capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V. FIG.

FIG. 4 is a plot of experimental data obtained at 40° C. of normalized capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V.

Fig. 3 is a plot of experimental data obtained at 40°C of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V.

17A-17F are plots of experimental data for capacity, normalized capacity, and voltage hysteresis for electrolyte systems including FEC, VC, and/or DTD.

4 is a plot of experimental data of capacity versus number of cycles for an electrolyte system containing FEC and/or DTD cycled up to 4.3V.

4 is a plot of experimental data of normalized capacity versus number of cycles for electrolyte systems containing FEC and/or DTD cycled up to 4.3V.

FIG. 2 is a plot of experimental data of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system including FEC and/or DTD cycled up to 4.3V; FIG.

4 is a plot of experimental data of capacity versus number of cycles for an electrolyte system containing VC and/or DTD cycled up to 4.3V.

4 is a plot of experimental data of normalized capacity versus number of cycles for electrolyte systems containing VC and/or DTD cycled up to 4.3V.

FIG. 2 is a plot of experimental data of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing VC and/or DTD cycled up to 4.3V; FIG.

4 is a plot of experimental data of capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V.

2 is a plot of experimental data of normalized capacity versus number of cycles for an electrolyte system containing FEC cycled up to 4.3V.

FIG. 4 is a plot of experimental data of voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system including FEC cycled up to 4.3V; FIG.

4 is a plot summarizing experimental data for the volume of forming gas produced during cell formation for different electrolyte systems.

2 is a plot summarizing experimental data of charge transfer impedance for different electrolyte systems.

FIG. 10 is a plot summarizing experimental data measuring the slow capacity loss of different electrolyte systems after cells were charged at 20° C. for 30 cycles at three different charge rates.

FIG. 2 is a plot summarizing experimental data summarizing peak capacity as a function of cycle number for different electrolyte systems used in cells being charged at 20° C. and different charge rates.

FIG. 2 is a plot summarizing experimental data summarizing peak capacity as a function of cycle number for different electrolyte systems used in cells being charged at 20° C. and different charge rates.

FIG. 10 is a plot summarizing experimental data for the volume of gas forming for different additives in MA solvent at various concentrations. FIG.

FIG. 2 is a plot summarizing experimental data of charge transfer impedance for different additives in electrolytes with varying concentrations of MA solvent. FIG.

FIG. 10 is a plot summarizing experimental data for slow capacity loss after charging at 1, 1.5, and 2C for 30 cycles at 20° C. with different electrolyte compositions.

FIG. 28 is an enlarged view of certain experimental data shown in FIG. 27;

FIG. 2 summarizes experimental data for DeltaV (difference between average charging voltage and average charging voltage) as a function of cycle number for an electrolyte system including FEC.

FIG. 2 summarizes experimental data for peak capacity as a function of cycle number for electrolyte systems containing FEC.

FIG. 2 summarizes experimental data of energy hysteresis as a function of cycle number for electrolyte systems containing FEC.

FIG. 2 summarizes experimental data for delta V (difference between average charging voltage and average charging voltage) as a function of cycle number for electrolyte systems containing VC.

FIG. 2 summarizes experimental data of peak capacity as a function of cycle number for electrolyte systems containing VC.

FIG. 2 summarizes experimental data of energy hysteresis as a function of cycle number for electrolyte systems containing VC.

Figures 35A-35D summarize experimental data for an electrolyte system with a positive electrode of NMC532 and a negative electrode of artificial graphite.

FIG. 10 summarizes experimental impedance data plotting the negative of the imaginary part of impedance against the real part of impedance for different electrolyte systems, including systems containing LFOs.

FIG. 10 summarizes experimental impedance data plotting the negative of the imaginary part of impedance versus the real part of impedance for different electrolyte systems including VC, PES, or LFO.

FIG. 10 summarizes experimental impedance data plotting the negative of the imaginary part of impedance against the real part of impedance for different electrolyte systems, including systems with FEC, DTD, or LFO.

FIG. 13 summarizes experimental impedance data for different electrolyte systems including VC, FEC, DTD, PES, or LFO, a positive electrode of NMC532, and a negative electrode of artificial graphite.

FIG. 13 summarizes experimental data for different electrolyte systems including VC, FEC, DTD, PES, or LFO.

Figures 37A-37F summarize experimental storage data for different electrolyte systems containing LFOs compared to controls without LFOs.

FIG. 2 summarizes the voltage drop data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 4.4 V for 500 hours at 60° C. FIG.

FIG. 2 summarizes the voltage drop data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 2.5 V for 500 hours at 60° C. FIG.

FIG. 13 summarizes volume change data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 4.4 V for 500 hours at 60° C. FIG.

Figure 2 summarizes volume change data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 2.5 V for 500 hours at 60°C.

FIG. 10 summarizes impedance data for different electrolyte systems with LFO compared to a control without LFO before and after the system was stored at 4.4 V for 500 hours at 60° C. FIG.

FIG. 10 summarizes impedance data for different electrolyte systems with LFO compared to a control without LFO before and after the system was stored at 2.5 V for 500 hours at 60° C. FIG.

Figures 38A-38F summarize experimental storage data for different electrolyte systems containing LFOs compared to controls without LFOs.

FIG. 2 summarizes the voltage drop data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 4.4 V for 500 hours at 60° C. FIG.

FIG. 2 summarizes the voltage drop data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 2.5 V for 500 hours at 60° C. FIG.

FIG. 13 summarizes volume change data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 4.4 V for 500 hours at 60° C. FIG.

Figure 2 summarizes volume change data for different electrolyte systems with LFO compared to a control without LFO after storing the system at 2.5 V for 500 hours at 60°C.

FIG. 10 summarizes impedance data for different electrolyte systems with LFO compared to a control without LFO before and after the system was stored at 4.4 V for 500 hours at 60° C. FIG.

FIG. 10 summarizes impedance data for different electrolyte systems with LFO compared to a control without LFO before and after the system was stored at 2.5 V for 500 hours at 60° C. FIG.

Figures 39A-39F summarize experimental data for different electrolyte systems with LFOs compared to controls without LFOs.

FIG. 10 summarizes Coulombic Efficiency (CE) versus number of cycles data for electrolyte systems, including systems containing LFOs, cycled to 4.1V.

FIG. 10 summarizes data on change in voltage versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.1V.

FIG. 10 summarizes end-of-charge capacity data plotted against cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.1V.

FIG. 2 summarizes normalized discharge capacity versus cycle number data for different electrolyte systems, including a system containing an LFO, cycled to 4.1V.

FIG. 10 summarizes Coulombic Efficiency (CE) versus number of cycles data for electrolyte systems, including systems containing LFOs, cycled to 4.2V.

FIG. 2 summarizes data on change in voltage versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.2V.

FIG. 10 summarizes end-of-charge capacity data plotted against cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.2V.

FIG. 2 summarizes normalized discharge capacity versus cycle number data for different electrolyte systems, including a system containing an LFO, cycled to 4.2V.

Figures 40A-40F summarize experimental data for different electrolyte systems with LFOs compared to controls without LFOs.

FIG. 10 summarizes Coulombic Efficiency (CE) versus number of cycles data for electrolyte systems, including systems containing LFOs, cycled to 4.3V.

FIG. 10 summarizes data for change in open circuit voltage versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.3V.

FIG. 10 summarizes end-of-charge capacity data plotted against cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.3V.

FIG. 2 summarizes normalized discharge capacity versus cycle number data for different electrolyte systems, including a system containing an LFO, cycled to 4.3V.

FIG. 10 summarizes Coulombic Efficiency (CE) versus number of cycles data for electrolyte systems, including systems containing LFOs, cycled to 4.4V.

FIG. 10 summarizes data for change in open circuit voltage versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.4V.

FIG. 2 summarizes end-of-charge capacity data plotted against cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.4V.

FIG. 2 summarizes normalized discharge capacity versus cycle number data for different electrolyte systems, including a system containing an LFO, cycled to 4.4V.

FIG. 2 summarizes data for coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.

FIG. 10 summarizes fragment fade vs. upper cutoff voltage data for different electrolyte systems, including systems containing LFOs.

FIG. 2 summarizes end-of-charge capacity slip versus upper cut-off voltage data for different electrolyte systems, including systems with LFOs.

FIG. 41B is an enlarged view of FIG. 41A summarizing data for coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.

FIG. 41B is an enlarged view summarizing fragmentary fade versus upper cutoff voltage data for different electrolyte systems, including systems containing LFOs.

FIG. 41C is an enlarged view summarizing end-of-charge capacity slip versus upper cut-off voltage data for different electrolyte systems, including systems containing LFOs.

Figures 43A-43D summarize long-term cycling data for different electrolyte systems, including systems containing LFOs.

Figure 2 summarizes normalized discharge capacity data for different electrolyte systems, including a system containing an LFO, cycled at 40°C.

FIG. 2 summarizes average charge voltage data for different electrolyte systems, including systems containing LFOs, cycled at 40°C.

Figure 2 summarizes normalized discharge capacity data for different electrolyte systems, including a system containing an LFO, cycled at 20°C.

FIG. 2 summarizes average charge voltage data for different electrolyte systems, including systems containing LFOs, cycled at 20°C.

Figures 44A-44D summarize long-term cycling data under fast charging for different electrolyte systems, including systems containing LFOs.

FIG. 2 summarizes normalized discharge capacity data for different electrolyte systems, including the system containing the LFO, cycled at 20° C. during the first experiment.

FIG. 4 summarizes average charge voltage data for different electrolyte systems, including the system containing the LFO, cycled at 20° C. during the first experiment.

FIG. 10 summarizes normalized discharge capacity data for different electrolyte systems, including a system containing an LFO, cycled at 20° C. during a second experiment.

FIG. 10 summarizes average charge voltage data for different electrolyte systems, including the system containing the LFO, cycled at 20° C. during the second experiment.

FIG. 13 summarizes voltage data for different electrolyte systems, including a system containing an LFO, when the cell is maintained at 40°C.

FIG. 13 summarizes volume change data for different electrolyte systems, including a system containing an LFO, when the cell is maintained at 40°C.

Figures 46A-46D summarize the voltage drop and impedance data generated during the storage experiments.

FIG. 13 summarizes the voltage drop data for different electrolyte systems, including the system containing the LFO, after the cell was maintained at 4.4 V and 60° C. for 500 hours.

FIG. 13 summarizes impedance data for different electrolyte systems, including a system containing an LFO, before and after the cell was held at 4.4 V and 60° C. for 500 hours.

FIG. 2 summarizes the voltage drop data for different electrolyte systems, including the system containing the LFO, after the cell was maintained at 2.5 V and 60° C. for 500 hours.

FIG. 13 summarizes impedance data for different electrolyte systems, including a system containing an LFO, before and after the cell was held at 2.5 V and 60° C. for 500 hours.

FIG. 4 shows exemplary data during specific charging and discharging conditions;

Figures 48A-48F summarize experimental heat flow data versus voltage. Figures 48A, 48C, and 48E show the results of the first cycle to 4.4V. Figures 48B, 48D and 48F show the results of the second cycle to 4.4V.

Experimental parasitic heat flow data as a function of voltage for different electrolyte systems, including a system with DTD in the voltage range of 4.0 V to 4.4 V during the first cycle, and a cell with parasitic heat flow and 2% VC + 1% DTD. Fig. 1 summarizes the difference between the parasitic heat flow of

Includes experimental parasitic heat flow data, and parasitic heat flow and 2% VC + 1% DTD as a function of voltage for different electrolyte systems, including a system with a DTD in the voltage range of 4.0 V to 4.4 V during the second cycle. Fig. 13 summarizes the differences with the parasitic heat flow of the cell;

Experimental parasitic heat flow data as a function of voltage for different electrolyte systems, including a system with an LFO in the voltage range of 4.0 V to 4.4 V during the first cycle, and a cell with parasitic heat flow and 2% VC + 1% DTD. Fig. 1 summarizes the difference between the parasitic heat flow of

Includes experimental parasitic heat flow data, and parasitic heat flow and 2%VC+1%DTD as a function of voltage for different electrolyte systems, including a system with an LFO in the voltage range of 4.0V to 4.4V during the second cycle. Fig. 13 summarizes the differences with the parasitic heat flow of the cell;

Experimental parasitic heat flow data as a function of voltage for different electrolyte systems, including a system with an LFO in the voltage range of 4.0 V to 4.4 V during the first cycle, and a cell with parasitic heat flow and 2% VC + 1% DTD. Fig. 1 summarizes the difference between the parasitic heat flow of

Includes experimental parasitic heat flow data, and parasitic heat flow and 2%VC+1%DTD as a function of voltage for different electrolyte systems, including a system with an LFO in the voltage range of 4.0V to 4.4V during the second cycle. Fig. 13 summarizes the differences with the parasitic heat flow of the cell;

Figures 50A-50C summarize experimental average parasitic heat flow data as a function of cycle number for different electrolyte systems.

FIG. 10 summarizes experimental average parasitic heat flow data as a function of cycle number for electrolyte systems containing 2% VC + 1% DTD and 2% FEC + 1% DTD.

Electrolyte systems including 0.5% LFO, 1% LFO, 1.5% LFO, 0.5% LFO + 1% VC + 1% FEC, 1.0% LFO + 1% VC + 1% FEC, and 1.5% LFO + 1% VC + 1% FEC FIG. 2 summarizes experimental average parasitic heat flow data as a function of the number of cycles of .

FIG. 10 summarizes experimental average parasitic heat flow data as a function of cycle number for electrolyte systems containing 1% LFO, 1% LFO + 1% VC, 1% LFO + 1% FEC, and 1% LFO + 1% VC + 1% FEC.

FIG. 50 summarizes experimental data from FIGS. 50A-50C showing the best performing cell from parasitic heat flow experiments.

Figures 52A-52D summarize experimental data for different electrolyte systems with LFOs compared to controls without LFOs cycled to 4.2V.

FIG. 10 summarizes coulombic efficiency versus cycle number data for electrolyte systems, including systems containing LFOs, cycled to 4.2V.

FIG. 10 summarizes end-of-charge capacity data plotted against cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.2V.

FIG. 2 summarizes data on change in voltage versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.2V.

FIG. 2 summarizes normalized discharge capacity versus cycle number data for different electrolyte systems, including a system containing an LFO, cycled to 4.2V.

Figures 53A-53D summarize experimental data for different electrolyte systems with LFOs compared to controls without LFOs cycled to 4.3V.

FIG. 13 summarizes coulombic efficiency versus cycle number data for electrolyte systems, including systems containing LFOs, cycled to 4.3V.

FIG. 10 summarizes end-of-charge capacity data plotted against cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.3V.

FIG. 10 summarizes data on change in voltage versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.3V.

FIG. 2 summarizes normalized discharge capacity versus cycle number data for different electrolyte systems, including a system containing an LFO, cycled to 4.3V.

Figures 54A-54D summarize experimental data for different electrolyte systems with LFOs compared to controls without LFOs cycled to 4.4V.

FIG. 2 summarizes experimental data of coulombic efficiency versus number of cycles for electrolyte systems, including systems containing LFOs, cycled to 4.4V.

FIG. 10 summarizes experimental data of end-of-charge capacity plotted against number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.4V.

FIG. 2 summarizes experimental data of voltage change versus number of cycles for different electrolyte systems, including a system containing an LFO, cycled to 4.4V.

FIG. 2 summarizes experimental data of normalized discharge capacity versus cycle number for different electrolyte systems, including a system containing an LFO, cycled to 4.4V.

FIG. 2 summarizes data for coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.

FIG. 10 summarizes fragment fade vs. upper cutoff voltage data for different electrolyte systems, including systems containing LFOs.

FIG. 2 summarizes end-of-charge capacity slip versus upper cut-off voltage data for different electrolyte systems, including systems with LFOs.

FIG. 55A is an enlargement of FIG. 55A summarizing data for coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.

FIG. 55B is an enlarged view of 55B summarizing fragmentary fade versus upper cutoff voltage data for different electrolyte systems, including systems containing LFOs.

FIG. 55C is an enlarged view summarizing end-of-charge capacity slip versus upper cut-off voltage data for different electrolyte systems, including systems containing LFOs.

FIG. 5 shows impedance data generated during ultra-precise cycling experiments.

Figures 58A-58D summarize experimental data for an electrolyte system containing an LFO with a positive electrode made from NMC622 with two different coatings.

Figure 2 summarizes experimental data for voltage drop after storage at 60°C for 500 of various electrolyte systems at 4.4V.

Figure 2 summarizes experimental data of impedance before and after storage at 60°C for 500 of various electrolyte systems at 4.4V.

Figure 2 summarizes experimental data of voltage drop after storage at 60°C for 500 of various electrolyte systems at 2.5V.

Figure 2 summarizes experimental data of impedance before and after storage at 60°C for 500 of the various electrolyte systems at 2.5V.

Guangzhou Tinci Materials Technology Co., Ltd. , Ltd. and Shenzhen Capchem Technology Co. , Ltd. 1 summarizes experimental data of mass change due to air exposure of LFOs over time.

Guangzhou Tinci Materials Technology Co., Ltd. , Ltd. and Shenzhen Capchem Technology Co. , Ltd. 1 summarizes experimental data for thermogravimetric analysis of the LFO of .

FIG. 1 shows basic components of a battery-powered electric vehicle (electric vehicle) 100 . The electric vehicle 100 includes at least one drive motor (traction motor) 102A and/or 102B, at least one gearbox 104A and/or 104B coupled to the corresponding drive motor 102A and/or 102B, a battery cell 106, and an electronic Includes device 108 . In general, battery cells 106 power the electronics of electric vehicle 100 and provide power to propel electric vehicle 100 using drive motors 102A and/or 102B. Electric vehicle 100 includes numerous other components not described herein but known to those skilled in the art. Although the structure of electric vehicle 100 in FIG. 1 is shown as having four wheels, different electric vehicles may have fewer or more than four wheels. Moreover, different types of electric vehicles 100 may incorporate the inventive concepts described herein, including engines for motorcycles, aircraft, trucks, boats, trains, among other types of vehicles. Certain parts made using embodiments of the present disclosure may be used in automobile 100 .

FIG. 2 is a schematic diagram of an exemplary energy storage system 200 showing various components. Energy storage system 200 typically includes a modular housing having at least one base 202 and four sidewalls 204 (only two are shown in the figure). The module housing is generally electrically isolated from the battery cells 206 contained therein. This may be done through physical separation, through electrically insulating layers, through selection of insulating material as the module housing, through any combination of these, or otherwise. The base 202 may be an electrically insulating layer over a metal sheet or non-conducting/electrically insulating material such as polypropylene, polyurethane, polyvinyl chloride, another plastic, non-conducting composite material, or insulating carbon fiber. Sidewalls 204 may also include an insulating layer or be formed of a non-conductive or electrically insulating material such as polypropylene, polyurethane, polyvinyl chloride, another plastic, non-conductive composite, or insulating carbon fiber. One or more interconnect layers 230 may be positioned over the battery cells 206 and the top plate 210 may be positioned over the interconnect layers 230 . Top plate 210 may be a single plate or may be formed of multiple plates.

The individual battery cells 106 and 206 are often lithium ion battery cells having electrolytes containing lithium ions and positive and negative electrodes. FIG. 3 shows a schematic diagram of a lithium ion cell 300 . Lithium ions 350 are dispersed throughout electrolyte 320 within container 360 . Container 360 may be part of a battery cell. Lithium ions 350 move between positive electrode 330 and negative electrode 340 . Separator 370 separates the negative and positive electrodes. Circuit 310 connects the negative and positive electrodes.

New research by the inventors has identified novel electrolytes and battery systems for use in grid and electric vehicle applications. These systems include 1) 1,3,2-dioxathiolane-2,2-dioxide (DTD, also known as ethylene sulfate) or vinylene carbonate (VC) in combination with another sulfur-containing additive, 2) DTD or fluoroethylene carbonate (FEC) in combination with another sulfur-containing additive, and 3) prop-1-ene-1,3-sultone (PES) in combination with DTD or another sulfur-containing additive, and It is based on a two-additive electrolyte system combined with electrodes. These two-additive electrolyte systems are lithium-nickel electrolytes having the composition _LNixMnyCozO2 (commonly abbreviated as NMC or NMCxyz, where x, y _, z are the molar ratios of _nickel , _manganese , and cobalt, respectively). It is paired with a positive electrode made from manganese cobalt oxide. In certain embodiments, the positive electrode is formed of NMC111, NMC532, NMC811, or NMC622. In certain embodiments, the NMC532 positive electrode formed of single-crystal, micrometer-sized particles, which results in an electrode having micrometer-sized regions of continuous crystal lattice (or particles), depends in part on materials and processing conditions. , have been shown to be particularly robust due to larger particle sizes than using conventional materials and processing conditions.

Typical processing conditions result in NMC electrodes packed with nanometer-sized particles in larger micrometer-sized agglomerates, forming nanometer-scale grain boundaries. Since grain boundaries are defects that tend to degrade desirable properties (eg, electrical properties), it is usually desirable to reduce the number of grains and increase the grain size. The treatment creates larger areas on the micrometer size scale, which reduces the number of grain boundaries in the NMC electrode and improves electrical properties. Improved performance results in a more robust battery system. In certain embodiments, separate NMC electrodes may be processed to create larger area sizes (micrometer size scale and above), e.g., NMC111, NMC811, NMC622, to create a more robust system. , or another NMC compound may be treated.

The positive electrode may be coated with _a material such as aluminum oxide ( _Al2O3 ), titanium dioxide ( _TiO2 ), or another coating. Coating the positive electrode is advantageous because it can help reduce interfacial phenomena at the positive electrode, such as parasitic reactions, thermal abuse, or other phenomena that can degrade the system. The negative electrode may be made from natural graphite, synthetic graphite, or another material.

Electrolytes include ethylene carbonate, ethyl methyl carbonate, methyl acetate, propylene carbonate, dimethyl carbonate, diethyl carbonate, another carbonate solvent (cyclic or acyclic), another organic solvent, and/or another non-aqueous solvent. , a lithium salt (such as _LiPF6 ) dissolved in a combination of organic or non-aqueous solvents. The solvent is present at a higher concentration than the additive, usually greater than 6% by weight. Experimental data were generated using electrolyte solvents including EC and EMC (with or without MA), but these solvents are merely examples of other non-aqueous solvents, particularly other carbonate solvents. EC and EMC solvents were used in experiments to control the systems tested to understand the effects of adding MA as additive, electrode, and solvent. Accordingly, the electrolyte system includes propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, another carbonate solvent (cyclic or acyclic), another organic solvent, and/or another non-aqueous solvent. , other carbonate solvents and/or other non-carbonate solvents may be used. The solvent is present at a higher concentration than the additive, usually greater than 6% by weight.

In the two-additive mixture FEC and DTD, the concentration of FEC is preferentially between 0.5 and 6% by weight and the concentration of DTD is preferentially between 0.25 and 5% by weight. In the two-additive mixture VC and DTD, the concentration of VC is preferentially between 0.5 and 6% by weight and the concentration of DTD is preferentially between 0.25 and 5% by weight.

Some of these new battery systems may also be used in energy storage and automotive applications (including energy storage in electric vehicles) where charge and discharge rates and longevity when rapidly charging and discharging are critical. . Specifically, MA can be used as an electrolyte solvent to extend life when charging and discharging at higher current rates.
[Pre-experiment setup]
Although the battery system itself may be differently packaged according to the present disclosure, the experimental setup is typically a battery using the usual set-up, including a two-additive electrolyte system and specific materials for the positive and negative electrodes. A machined "pouch cell" was used to systematically evaluate the system. All percentages referred to within this disclosure are weight percentages unless otherwise specified. The type of additive used and the concentration employed will depend on the properties to be most desirably improved, as well as the other components and designs used within the lithium-ion battery being made, and is separate from this disclosure. Those skilled in the art will understand that.

[Pouch cell]
The pouch cells used in the experimental set-up are 1 M Li
Contains _PF6 . Depending on the concentration of methyl acetate (0, 20, or 40%), the electrolyte is (1) 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate, (2) 24% ethylene carbonate, 1.2 M _LiPF6 in 56% ethyl methyl carbonate and 20% methyl acetate, or (3) 1.2 _M LiPF6 in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate. , 1M of _LiPF6 . Additive components were added to the electrolyte at the specified weight percentages.

The pouch cells used positive electrodes made of NMC532 with micrometer-sized particles (sometimes referred to as monocrystalline NMC532) and negative electrodes made of synthetic graphite, unless otherwise specified. Another positive electrode, including standard NMC532 (which has smaller particles than NMC, which has micrometer-sized particles) and NMC622, and a negative electrode (including natural graphite), were used to test a particular battery system.

Prior to electrolyte filling, the pouch cells were cut open under a heat seal and dried at 100° C. under vacuum for 12 hours to remove any residual water. The cell was then immediately transported to an argon-filled glovebox for filling and vacuum sealing and then filled with electrolyte. After filling, the cell was vacuum sealed.

After sealing, the pouch cells were placed in a temperature box at 40.0±0.1° C. and held at 1.5 V for 24 hours to complete wetting. The pouch cells were then subjected to a forming process. Unless otherwise specified, the forming process consisted of charging the pouch cell at 11 mA (C/20) to 4.2V and discharging to 3.8V. C/x indicates that the time to charge or discharge a cell at the selected current is x hours when the cell has its initial capacity. For example, C/20 indicates that charging or discharging takes 20 hours. After formation, the cell was transported and moved into a glove box, cut open to release any forming gas, vacuum sealed again, and the appropriate experiments performed.

[Electrochemical Impedance Spectroscopy]
After storage and formation, electrochemical impedance spectroscopy (EIS) measurements were performed on the pouch cells. The cells were charged or discharged to 3.8V and then transported to a temperature box set at 10.0±0.1°C. AC impedance spectra were collected at 10.0±0.1° C. with a signal amplitude of 10 mV, from 100 kHz to 10 mHz with a resolution of 10 points per decade.

Effect of LFO on Impedance: In certain embodiments, an LFO is included in the two or three electrolyte additive system to partially lower the impedance of the system. Figures 35A-35D show that in most cases _LiPO2F2 ( _LFO , or lithium difluorophosphate) lowers the cell impedance after formation. However, an increase in impedance is observed when the LFO is included with 2% PES + 1% DTD + 1% TTSPi (collectively PES211). The positive electrode is single crystal NMC532 and the negative electrode is artificial graphite.

Figures 35A-35D summarize experimental data for an electrolyte system with a positive electrode of NMC111 and a negative electrode of artificial graphite. After formation, the pouch cells were measured at 10°C and 3.8V. The control electrolyte for FIGS. 35A-35D is 1.0 M LiPF ₆ in 30% ethylene carbonate and 70% ethylmethyl carbonate. Figure 35A is 1.0 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate (control electrolyte); 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; _LiPO2F2 ; control electrolyte ₊ 2%
Experimental impedance data are summarized by plotting the negative of the imaginary part of impedance against the real part of impedance for LiPO ₂ F ₂ ; and 20% methyl acetate + 1% LiPO ₂ F ₂ . Figure 35B shows for the control electrolytes (same _control as Figure 35A), 2% VC, 2% VC + 1% _LiPO2F2 ; 20% MA + 1% _LiPO2F2 + ₂ % _{VC ;} PES211; Plotting the negative of the imaginary part of impedance against the real part of impedance summarizes the experimental impedance data. FIG. 35C shows the imaginary part of the impedance versus the real part of the impedance for the control electrolyte (same control as in FIG. 35A), 2% FEC, 2% _FEC + 1% _LiPO2F2 ; 1% _DTD ; and 1% DTD + ₁ % LiPO2F2. The negative part is plotted to summarize the experimental impedance data. Figure 35D is a control electrolyte ( _same control as Figure 35A); 1.2M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1% _LiPO2F2 ; ₂ % _LiPO2F2 ; % _LiPO2F2 ;2 _% VC;2%VC+1% _LiPO2F2 ;20%MA+1% _LiPO2F2 +2%VC;PES211; _PES211 +1% _LiPO2F2 ;2 _% FEC, 2% _FEC +1% _{LiPO2 1% DTD; and 1% DTD+1% LiPO 2 F 2 experimental impedance} data are summarized.

As can be seen in Figures 35A-35D, adding an LFO to most systems lowers the impedance. However, when the PES 211 is present, the addition of the LFO raises the impedance.

Figure 36 shows 2% VC in an electrolyte solution of 1.2 M _LiPF6 in 30% ethylene _carbonate and 70% ethyl methyl carbonate; 1% _LiPO2F2 + 2% VC; 1% _LiPO2F2 + 2% FEC _. and experimental EIS data for electrolyte systems containing additives of 1% LiPO ₂ F ₂ +1% VC + 1% FEC. EIS measurements were taken after formation at 3.8 V and 10°C. The positive electrode is single crystal NMC532 and the negative electrode is artificial graphite.

The LFO did not lower the impedance of the tested system with NMC532 positive and artificial graphite negative electrodes. The large cathode or anode surface may have not lowered the impedance. However, the LFO also did not raise the impedance. Therefore, adding an LFO does not lower or neutral the impedance.

[Ultra-precision cycling and storage experiments]
Ultra high precision cycling (UHPC) was performed to study the effectiveness of the battery system of the present disclosure, including effective electrolyte additives and electrodes. A standard UHPC procedure consists of cycling the cell between 2.8 and 4.3 V at 40° C. using a current corresponding to C/20 for 15 cycles to generate the data. For coulombic efficiency, UPHC is employed to measure coulombic efficiency, end-of-charge capacity slip, and other parameters to an accuracy of 30 ppm. Details of the UHPC procedure are described in T.W. M. Bond, J. C. Burns, D.; A. Stevens, H.; M. Dahn, andJ. R. Dahn, Journal of the Electrochemical Society, 160, A521 (2013).

Metrics measured and/or determined from UHPC measurements of particular interest include: Coulombic Efficiency, Normalized Coulombic Inefficiency, Normalized End-of-Charge Capacity Slip, Normalized Discharge Capacity (or Fade Rate), and DeltaV. Coulombic efficiency is the discharge capacity (Q _d ) divided by the previous cycle's charge capacity (Q _c ). It tracks the parasitic reactions taking place within the Li-ion cell and includes contributions from both the positive and negative electrodes. A higher CE value indicates less degradation of the electrolyte in the cell. Coulombic inefficiency per hour (CIE/h) is the normalized (per hour) coulombic inefficiency, where coulombic inefficiency is defined as 1-CE. This is calculated by taking 1-CE and dividing by the time of the cycle over which CE was measured. The end-of-charge capacity motion (or slip) tracks the parasitic reactions occurring at the positive electrode, as well as the positive material mass loss, if any. Less exercise is better and is associated with less electrolyte oxidation. Normalized discharge capacity, or fade rate, is another important metric, with lower fade rates being desirable and generally indicative of longer life battery systems. DeltaV is calculated as the difference between the average charge voltage and the average discharge voltage. The change in delta-V is closely related to the polarization growth, and the smaller the change in delta-V when cycling is performed, the better. UHPC measurements are particularly well-suited for comparing electrolyte compositions as they allow the tracking of metrics with greater accuracy and precision and permit the evaluation of different degradation mechanisms at relatively high speeds.

Two-electrolyte system with FEC or VC as additive: In certain embodiments, a two-additive electrolyte system with a concentration of about 0.25-6% for each additive forms part of the battery system. The battery system may also include a positive electrode made from NMC111, NMC532, NMC811, NMC622, or another NMC composition (NMCxyz). In certain embodiments, positive electrodes made from NMC532 with micrometer-scale particles are particularly robust, in part because the processing conditions created larger grain sizes than do normal processing conditions. was shown as

Typical processing conditions result in MC electrodes packed with nanometer-sized particles in larger micrometer-sized agglomerates, forming nanometer-scale grain boundaries. Since grain boundaries are defects that tend to degrade desirable properties (eg, electrical properties), it is usually desirable to reduce the number of grains and increase the grain size. Current processing creates larger areas on the micrometer size scale, thereby reducing the number of grain boundaries in the NMC electrode and improving electrical properties. Improved performance results in a more robust battery system. In certain embodiments, separate NMC electrodes may be processed to create larger area sizes (micrometer size scale and above), e.g., NMC111, NMC811, NMC622, to create a more robust system. , or another NMC compound may be treated.

The positive electrode may be coated with _a material such as aluminum oxide ( _Al2O3 ), titanium dioxide ( _TiO2 ), or another coating. Figures 4A-4J show novel in a base electrolyte system containing 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate using a positive electrode composed of single crystal NMC532 and a negative electrode composed of artificial graphite. 2 shows typical experimental data for the two-additive system of the present disclosure collected during UHPC experiments comparing a simple two-additive electrolyte system (VC+DTD and FEC+DTD) with a single-additive electrolyte system. Figures 4A-4J illustrate the advantages of the two-additive system of the present disclosure, specifically adding DTD to an electrolyte system containing VC or FEC.

FIG. 4A shows the time-normalized coulombic inefficiency per hour (CIE/h) versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD. FIG. 4B shows coulombic efficiency (CE) versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD. FIG. 4C shows end-of-charge capacity plotted against cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD. FIG. 4D shows discharge capacity versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD. FIG. 4E shows the difference between the average charge and discharge voltage versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC+1% DTD. FIG. 4F shows the time-normalized coulombic inefficiency per hour (CIE/h) versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD. FIG. 4G shows coulombic efficiency (CE) versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD. FIG. 4H shows end-of-charge capacity plotted against cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD. FIG. 4I shows discharge capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD. FIG. 4J shows the difference between the average charge and discharge voltage versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC+1% DTD.

Figures 4A-4J show the benefits of electrolytes with two additives, specifically VC + DTD and FEC + DTD. Experimental data show that the addition of DTD to an electrolyte system containing VC or FEC in a base electrolyte system containing 1.2 M LiPF in 30% ethylene carbonate and ₇₀ % ethyl methyl carbonate by weight only added VC or FEC. It has been shown that the performance of the electrolyte system containing it as an agent is enhanced. Specifically, FIGS. 4A-4J show that two-additive systems containing (VC+DTD and FEC+DTD) have higher CE (cell (lower electrolyte degradation in the positive electrode) and lower end-of-charge dynamics (lower electrolyte degradation at the positive electrode). In addition, FIGS. 4A-4J also show the desired low fade rate (Q _d ). Therefore, electrolyte systems with two additives (VC + DTD and/or FEC + DTD) perform better than electrolyte systems with only a single additive of DTD, VC, or FEC (CIE/h, CE, end-of-charge slip ) works well.

FIG. 5 summarizes the last three cycles of data generated during the experiments shown in FIGS. 4A-4J. FIG. 5A shows the end of time-normalized coulombic inefficiencies per hour (CIE/h) for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC+1% DTD, 2% VC, and 2% VC+1% DTD. shows a summary of the three cycles of FIG. 5B shows a summary of the last three cycles of fragment sliding per hour for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC+1% DTD, 2% VC, and 2% VC+1% DTD. FIG. 5C shows a summary of the last three cycles of fragment fade per hour for 1%DTD, 2%FEC, 2%FEC+1%DTD, 2%VC, and 2%VC+1%DTD.

Figures 5A-5C show that electrolyte systems containing VC + DTD and VC + DTD show lower normalized coulomb non-reduction compared to systems containing only one additional additive: 2% FEC, 2% VC, or 1% DTD. efficiency (CIE/h), and exhibit lower fragment slip per hour, meaning that these electrolyte systems have a longer lifetime. Figures 5A and 5B show that 1% DTD without another additive exhibits the highest CIE/h and fragment slip. However, when DTD is combined with VC or FEC, the two additives form a previously unexpected synergistic effect, with two-additive electrolyte systems being better than either single additive. Reduces CIE/h and fragment slippage. FIG. 5C shows that the presence of 1% DTD as a single additive or as part of a two-additive electrolyte system with VC or FEC reduces fragment fade per hour. This indicates that DTD is an important additive for extending the life of the battery system of the present invention. In addition to DTD, other sulfur-containing compounds can work similarly to extend battery life.

Methyl Acetate as Electrolyte Solvent: In certain embodiments, when higher charge and discharge rates are expected in addition to other properties, as a solvent (at concentrations up to 60% ) methyl acetate is used. This is of particular importance for vehicles and other applications. FIGS. 9A-9I show that methyl acetate can be added to electrolyte systems containing VCs or FECs with DTDs to increase electrolyte conductivity and reduce viscosity without significantly sacrificing lifetime. Typical data collected during precision charging experiments are shown. Improved conductivity and reduced viscosity are important for certain applications requiring higher charging rates.

Figure 9A shows 2% FEC in base electrolyte of 1.2 _{M LiPF6} in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC + 1% DTD in base electrolyte; 2% FEC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% FEC + 1% DTD in base electrolyte of 1.2 M _LiPF6 in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% FEC+1% DTD in a base electrolyte of 1.2 M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, _and 40% methyl acetate. Figure 2 shows coulombic efficiency (CE) versus number of cycles for the system.

Figure 9B shows ₂ % FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethylmethyl carbonate; 2% FEC + 1% DTD in base electrolyte; 2% FEC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% FEC + 1% DTD in base electrolyte of 1.2 M _LiPF6 in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% FEC+1% DTD in a base electrolyte of 1.2 M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, _and 40% methyl acetate. Figure 2 shows end-of-charge capacity plotted against system cycle number.

FIG. 9C shows ₂ % FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethylmethyl carbonate; 2% FEC + 1% DTD in base electrolyte; 2% FEC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% FEC + 1% DTD in base electrolyte of 1.2 M _LiPF6 in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% FEC+1% DTD in a base electrolyte of 1.2 M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, _and 40% methyl acetate. Figure 2 shows discharge capacity versus number of cycles for the system.

FIG. 9D shows ₂ % FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC + 1% DTD in base electrolyte; 2% FEC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% FEC + 1% DTD in base electrolyte of 1.2 M _LiPF6 in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% FEC+1% DTD in a base electrolyte of 1.2 M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, _and 40% methyl acetate. Figure 2 shows the difference between the average charge voltage and the average discharge voltage versus the number of cycles for the system.

Figure 9F shows ₂ % VC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethylmethyl carbonate; 2% VC + 1% DTD in base electrolyte; 2% VC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% VC + 1% DTD in base electrolyte of LiPF ₆ 1.2M in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% VC+1% DTD in a base electrolyte of _{1.2M LiPF6} in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. Figure 2 shows coulombic efficiency (CE) versus number of cycles for the system.

2% VC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in base electrolyte; 2% VC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% VC + 1% DTD in base electrolyte of LiPF ₆ 1.2M in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% VC+1% DTD in a base electrolyte of _{1.2M LiPF6} in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. Figure 2 shows charge endpoint plotted against system cycle number.

2% VC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in base electrolyte; 2% VC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene carbonate, 56 2% VC + 1% DTD in base electrolyte of LiPF ₆ 1.2M in % ethyl methyl carbonate and 20% methyl acetate; 1.2 M in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate and 2% VC+1% DTD in a base electrolyte of _{1.2M LiPF6} in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. Figure 2 shows discharge capacity versus number of cycles for the system.

2% VC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in base electrolyte; 2% VC in base electrolyte of 1.2 M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 24% ethylene
2% VC + 1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate and 2% VC in a base electrolyte of 1.2 M _LiPF6 in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate + ₁ %. Figure 2 shows the difference between the average charge voltage and the average discharge voltage versus cycle number for an electrolyte system containing DTD.

Figures 9A-9I show that in systems containing both VC and FEC, the addition of MA as an electrolyte solvent does not significantly compromise the overall performance of the battery system, and the long-term cycling described later. and as plating experiments show, this extends the life under higher charging rates. In particular, the performance of the two-additive electrolyte system of the present disclosure is not sacrificed with the addition of MA as a solvent. FIGS. 10A-10C show averages of the last three cycles of data generated during the experiments shown in FIGS. 9A-9I. Figures 10A-10C confirm that the addition of MA as an electrolyte solvent does not significantly compromise the overall performance of the battery system of the present disclosure, including the two-additive electrolyte system.

LFOs as Additives: Figures 39A-39H and Figures 40A-40H demonstrate that LFOs perform well overall in electrolyte systems, such that system performance performs well compared to control electrolytes. summarizes the results of UHPC experiments, showing

Figures 37A-37F and 38A-38F summarize experimental storage data for different electrolyte systems containing LFOs compared to controls without LFOs.

Figures 37A-37F show that LFO dramatically improves storage in the absence of other additives. When LFOs are added, voltage drop is dramatically reduced, gassing is dramatically reduced, and impedance is dramatically reduced after storage. LFO is effective even in the presence of MA. Figures 38A-38F show similar results when an LFO is added to an EC/DMC-based electrolyte. When a good additive package such as 1% FEC + 1% DTD is used, the additional benefit provided by LFO is small. However, DTD-based electrolyte systems may be excluded in the future as they often change color over time when mixed and stored in a glovebox.

Figures 46A-46D show the results of cell storage experiments, demonstrating the ability of more complex electrolytes to rival 2% FEC + 1% DTD in storage performance.

Figures 52A-52D, Figures 53A-53D, Figures 54A-54D, and Figures 55A-55C show results for additional electrolyte systems that also include an LFO and 2% VC + 1% DTD for comparison purposes. . As can be observed, the electrolyte system with LFO performs as well as or better than the 2% VC + 1% DTD system. Figures 56A-56C show the results of additional experiments for CIE, fragment fade, and fragment slip. An electrolyte system of 2% VC + 1% DTD works very well. Electrolyte systems of 1% LFO + 2% VC and 1% LFO + 1% VC + 1% FEC also work well (although not as well as the 2% VC + 1% DTD system). This experimental data is consistent with the TAM experimental data.

FIG. 57 shows the effect of UHPC cycling on impedance. The LFO system works well overall. 58A-58D summarize experimental data for an electrolyte system containing an LFO with a positive electrode made from NMC622 with two different coatings indicated as A and B. FIG. In the different electrolyte systems studied, the LFO also affects the voltage drop and impedance reduction of the system.

The LFO is manufactured by Guangzhou Tinci Materials Technology Co., Ltd. , Ltd. and Shenzhen Capchem Technology Co. , Ltd. can be obtained by multiple sources, including Figure 60 shows that regardless of the source, the reaction rates are similar in the presence of air for periods of at least 50 minutes or less. FIG. 61 shows similar mass loss through thermogravimetric analysis (“TGA”) experiments performed in an argon environment with a temperature gradient of 5° C./min.

[Long-term cycling]
Battery system life is an important characteristic of a battery system. Charge and discharge rates can affect longevity. Long-term cycling experiments help determine the resilience of battery systems over time under expected operating conditions. Selecting a battery system that has sufficient life for the desired application is important.

Embodiments of the present disclosure present desirable long-term cycling for different applications, including grid and vehicle storage. Specifically, the VC+DTD and FEC+DTD two-additive electrolyte systems, in which concentrations of up to 60% MA are used as solvents, are typically found in automotive applications (particularly of particular relevance for energy storage in electric vehicles).

In long-term cycling experiments, single crystal NMC532 was normally used as the positive electrode (unless otherwise specified) and synthetic graphite was used as the negative electrode (unless specified otherwise). Pouch cells were subjected to a forming process prior to long-term cycling experiments. First, the cell was charged at 11 mA (C/20) to 4.2V and discharged to 3.8V. The cell was transported and moved into the glovebox, cut open to release the evolved gas, and then vacuum sealed again. After formation, the cells were cycled in the Neware charging system. The cell was housed in a temperature controlled box at 40°C ± 0.2°C or 20°C ± 0.2°C. Between 3.0 V and the upper charge limit (4.2 V or 4.3 V) with a current of C/3 (3h half cycle) and a constant voltage step at the upper charge limit until the current drops below C/20 Cycled the cell. Every 50 cycles, the cell was subjected to one complete cycle at C/20.

Two-electrolyte system with FEC or VC as additive: In certain embodiments, a two-additive electrolyte system with a concentration of about 0.25-6% for each additive forms part of the battery system. Figures 6A-6F show typical experimental data studying long-term cycling at 40°C, C/3 constant charge, constant voltage (CCCV) charge rate. Figures 6A-6F illustrate the advantages of the two-additive electrolyte system of the present disclosure, specifically electrolytes containing DTDs with VC or FEC. Figure 6A shows capacity versus cycle for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.2V. A number of experimental data are presented. Figure 6B is the normalized capacity of electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.2V. Experimental data versus number of cycles are shown. FIG. 6C shows the voltage hysteresis ( Experimental data of the difference between the average charge voltage and the average discharge voltage) vs. number of cycles are shown. Figure 6D shows capacity versus cycle for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.2V. A number of experimental data are presented. FIG. 6E is the normalized capacity of electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.2V. Experimental data versus number of cycles are shown. FIG. 6F is 1% DTD, 2% FEC, 2% F, cycling between 3.0V and 4.2V
Fig. 2 shows experimental data of voltage hysteresis versus number of cycles for electrolyte systems containing EC + 1% DTD, 2% VC, and 2% VC + 1% DTD. Experimental data show that the two-additive electrolyte systems (DTD+FEC and DTD+VC) have lower capacity loss when cycled to 4.2 or 4.3 V and more V when compared to single-additive electrolyte systems of VC or FEC. It is shown to experience low polarization growth.

Figures 7A-7F show typical experimental data for long-term cycling at 20°C and C/3 CCCV charging rate. Similar to FIGS. 6A-6F, FIGS. 7A-7F illustrate the benefits of including DTD as an additive in electrolyte systems containing VCs or FECs. Figures 7A-7F confirm that the benefits seen at 40°C are still seen at lower temperatures, in this case 20°C. FIG. 7A shows capacity versus cycle for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC+1% DTD, 2% VC, and 2% VC+1% DTD cycling between 3.0 V and 4.3 V. A number of experimental data are presented. Figure 7B is the normalized capacity of electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD cycled between 3.0V and 4.3V. Experimental data versus number of cycles are shown. FIG. 7C shows the voltage hysteresis ( Experimental data of the difference between the average charge voltage and the average discharge voltage) vs. number of cycles are shown. FIG. 7D shows capacity versus cycle for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC+1% DTD, 2% VC, and 2% VC+1% DTD cycling between 3.0 V and 4.3 V. A number of experimental data are presented. FIG. 7E shows the normalized capacity of electrolyte systems containing 1% DTD, 2% FEC, 2% FEC+1% DTD, 2% VC, and 2% VC+1% DTD cycled between 3.0 V and 4.3 V. Experimental data versus number of cycles are shown. FIG. 7F shows the voltage hysteresis ( Experimental data of the difference between the average charge voltage and the average discharge voltage) vs. number of cycles are shown. Figures 7A-7F confirm the advantage of including a DTD in the electrolyte with VC or FEC, especially when cycling is performed up to 4.3V.

Figures 6A-6F show the advantage of a two-additive electrolyte system consisting of DTD+VC or DTD+FEC. FIGS. 6A-6F show that cycling at 40° C. with DTDs with VC or FEC as part of a two-additive electrolyte system reduces capacity loss at 4.2 V or 4.3 V and promotes polarized growth. It shows that it decreases. Similarly, Figures 7A-7F show the benefit of DTD upon long-term cycling at 20°C. 7A-7F show that cycling at 20° C. with DTDs with VC or FEC as part of a two-additive electrolyte system yielded 4.2 V (slightly) and 4.3 V (more significantly) This indicates that it reduces the capacity loss of the s to reduce the polarization growth. Thus, at both 20° C. and 40° C., two-additive systems containing DTDs with VC or FEC improve battery systems by reducing capacity loss and reducing polarization growth.

In certain embodiments, the positive electrode is formed of NMC111, NMC532, NMC822, NMC622, and/or NMCxyz. In particular, the grain size of NMC532 is larger than that of other, more polycrystalline, standard MC materials, which have smaller grain sizes, so positive electrodes made of single crystal NMC532 are particularly shown to be robust. 8A-8I show typical empirical data collected during cycling experiments of electrolyte compositions according to certain embodiments of the present disclosure, including cathodes formed from single crystal NMC532. FIG. 8A Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethylmethyl carbonate, 2% FEC, 1% Figure 2 shows experimental data of peak capacity versus cycle number for electrolyte systems including FEC + 1% DTD, 2% FEC + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS. FIG. 8B Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, 2% FEC, 1% Figure 2 shows experimental data for normalized capacity versus cycle number for electrolyte systems including FEC + 1% DTD, 2% FEC + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS. FIG. 8C 2% FEC, 1% cycling between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethylmethyl carbonate. Fig. 2 shows experimental data of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus number of cycles for electrolyte systems including FEC + 1% DTD, 2% FEC + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS. . FIG. 8D Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, 2% VC, 1% Figure 2 shows experimental data of peak capacity versus cycle number for electrolyte systems containing VC + 1% DTD, 2% VC + 1% DTD, 1% VC + 1% MMDS, and 2% VC + 1% MMDS. FIG. 8E Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, 2% VC, 1% Figure 2 shows experimental data for normalized capacity versus cycle number for electrolyte systems containing VC + 1% DTD, 2% VC + 1% DTD, 1% VC + 1% MMDS, and 2% VC + 1% MMDS. FIG. 8F is a 2% FEC by weight cycled between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. , 1% VC + 1% DTD, 2% VC + 1% DTD, 1% VC + 1% MMDS, and 2% VC + 1% MMDS. Show data. FIG. 8G Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, 2% PES, 1% Figure 2 shows experimental data of peak capacity versus cycle number for electrolyte systems containing PES + 1% DTD, 2% PES + 1% DTD, 1% PES + 1% MMDS, and 2% PES + 1% MMDS. FIG. 8H Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, 2% PES, 1% Figure 2 shows experimental data for normalized capacity versus cycle number for electrolyte systems containing PES + 1% DTD, 2% PES + 1% DTD, 1% PES + 1% MMDS, and 2% PES + 1% MMDS. FIG. 8I Cycles between 3.0 V and 4.3 V at 40° C. in a base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, 2% FEC, 1% Figure 2 shows experimental data for voltage hysteresis (difference between average charge voltage and average discharge voltage) for electrolyte systems containing PES + 1% DTD, 2% PES + 1% DTD, 1% PES + 1% MMDS, and 2% PES + 1% MMDS. Figures 8A-8I show that NMC532 performs well with 1% DTD two-additive electrolyte systems with 1% VC, 2% VC, 1% FEC, or 2 FEC. DTD performed better as an additive with VC or FEC than MMDS.

Methyl Acetate as Electrolyte Solvent: In certain embodiments, methyl acetate is used as the electrolyte solvent at concentrations up to 60% (by weight), generally in combination with ethylene carbonate and/or ethyl methyl carbonate. Figures 15A-15F and 16A-16F show the results of experiments conducted at 20°C and 40°C, respectively. Cells with DTD performed better than cells without DTD in cells with MA as solvent.

15A, 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.2 V; in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1% FEC + 1% DTD in a base electrolyte of 1.2 M _LiPF6 ; 24% ethylene carbonate, 56
2% FEC in the base electrolyte of 1.2 M _LiPF6 in % ethyl methyl carbonate, and 20% methyl acetate; 2% FEC + 1% DTD in a base electrolyte of LiPF ₆ ; 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and 18% ethylene. Experiments obtained at 20°C of capacity vs. cycle number for electrolyte systems containing 2% FEC + 1% DTD in a base electrolyte of 1.2 M _LiPF6 in carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. It is a plot of the data.

FIG. 15B, 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethylmethyl carbonate cycled up to 4.2 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; FIG. 2 is a plot of experimental data obtained at 20° C. of normalized capacity versus number of cycles for an electrolyte system containing 2% FEC+1% DTD; FIG.

FIG. 15C, 2% FEC in base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.2 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; Fig. 3 is a plot of experimental data obtained at 20°C of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus cycle number for an electrolyte system containing 2% FEC + 1% DTD;

FIG. 15D, 2% FEC in base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.3 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; FIG. 2 is a plot of experimental data obtained at 20° C. of capacity versus number of cycles for an electrolyte system containing 2% FEC+1% DTD; FIG.

FIG. 15E 2% FEC in base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.3 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; FIG. 2 is a plot of experimental data obtained at 20° C. of normalized capacity versus number of cycles for an electrolyte system containing 2% FEC+1% DTD; FIG.

FIG. 15F, 2% FEC in base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.3 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; Fig. 3 is a plot of experimental data obtained at 20°C of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus cycle number for an electrolyte system containing 2% FEC + 1% DTD;

Figures 15A-15F show the importance of DTD in systems with FEC and in systems using MA as a solvent at 20°C. Cells with DTD performed better than cells without DTD, especially in cells with MA. In particular, 2% FEC + 1% DTD with 20% MA solvent shows very stable capacity retention at 4.3V.
Figures 16A-16F show the results of experiments conducted at 40°C. Cells with DTD performed better in cells with MA than cells without DTD. 16A, 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.2 V; in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; FIG. 2 is a plot of experimental data obtained at 40° C. of capacity versus number of cycles for an electrolyte system containing 2% FEC+1% DTD; FIG.

FIG. 16B 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethylmethyl carbonate cycled up to 4.2 V; in 30% ethylene carbonate and 70% ethylmethyl carbonate; 1.2 M Li
1% FEC + 1% DTD in a base electrolyte of _PF6 ; 2% FEC in a base electrolyte of 1.2M _LiPF6 in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; ethylene 24% ethylene. 2% FEC + 1% DTD in base electrolyte of 1.2 M _LiPF6 in carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate 2% FEC in a base electrolyte of 1.2 M _LiPF6 ; and 2% FEC+1% DTD in a base electrolyte of 1.2 M _LiPF6 in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. 1 is a plot of experimental data obtained at 40° C. of normalized capacity versus cycle number for an electrolyte system comprising

FIG. 16C, 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethylmethyl carbonate cycled up to 4.2 V; in 30% ethylene carbonate and 70% ethylmethyl carbonate; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; Fig. 3 is a plot of experimental data obtained at 40°C of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus cycle number for an electrolyte system containing 2% FEC + 1% DTD;

FIG. 16D, 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.3 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; FIG. 2 is a plot of experimental data obtained at 40° C. of capacity versus number of cycles for an electrolyte system containing 2% FEC+1% DTD; FIG.

FIG. 16E 2% FEC in base electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethylmethyl carbonate cycled up to 4.3 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; FIG. 2 is a plot of experimental data obtained at 40° C. of normalized capacity versus number of cycles for an electrolyte system containing 2% FEC+1% DTD; FIG.

FIG. 16F, 2% FEC in base electrolyte of 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate cycled up to 4.3 V; 1% FEC + 1% DTD in a base electrolyte of 1.2 M LiPF ₆ at 2% FEC in a base electrolyte of 1.2 M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate. 2% FEC+1% DTD in base electrolyte of 1.2 M _LiPF6 in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40%; 2% FEC in a base electrolyte of 1.2 _{M LiPF6} in % methyl acetate; Fig. 3 is a plot of experimental data obtained at 40°C of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus cycle number for an electrolyte system containing 2% FEC + 1% DTD;

Figures 16A-16F show the importance of DTD in systems with FEC and in systems using MA as solvent at 40°C. In general, cells with DTD performed better than cells without DTD, especially in cells with MA. In the two-additive electrolyte system with 2% FEC + 1% DTD with 20% MA solvent, the effect of DTD is slightly weakened compared to the same two-additive electrolyte system without MA as solvent. Furthermore, the addition of up to 40% MA at 4.3V reduces the cycle life. That is, DTD and MA can have a symbiotic increase in the performance of the two-additive electrolyte system, but this increase diminishes when cycled up to 4.3V. Therefore, in certain embodiments of the present disclosure, the electrolyte system only operates up to 4.2V. In another embodiment of the present disclosure, the electrolyte system operates up to 4.3V, but for MA concentrations less than 40%.

NMC622 as positive electrode: In certain embodiments, the battery system has a positive electrode made from NMC622. In certain _embodiments , the positive electrode is coated with a material such as aluminum oxide ( _Al2O3 ), titanium dioxide ( _TiO2 ), or another coating. 17A-17F show experimental data for long-term cycling of one-additive or two-additive electrolyte systems with coated NMC622 as the positive electrode at 40° C., C/3CCCV. Dashed lines are extrapolations from experimental data.

More specifically, FIG. 17A is a plot of capacity versus cycle number experimental data for electrolyte systems containing FEC and/or DTD cycled up to 4.3V. FIG. 17B is a plot of experimental data of normalized capacity versus number of cycles for electrolyte systems containing FEC and/or DTD cycled up to 4.3V. FIG. 17C is a plot of experimental data of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus number of cycles for electrolyte systems containing FEC and/or DTD cycled up to 4.3V. FIG. 17D is a plot of experimental data of capacity versus number of cycles for electrolyte systems containing VC and/or DTD cycled up to 4.3V. FIG. 17E is a plot of experimental data of normalized capacity versus number of cycles for electrolyte systems containing VC and/or DTD cycled up to 4.3V. FIG. 17F is a plot of experimental data of voltage hysteresis (difference between average charge voltage and average discharge voltage) versus number of cycles for an electrolyte system containing VC and/or DTD cycled up to 4.3V.

Figures 17A-17F show that even when different cathodes were selected, the experimental data show that the electrolyte system with two additives, namely VC + DTD and FEC + DTD, favors VC,
The results show that either FEC or DTD perform better than either single additive.

Natural graphite as the negative electrode: In certain embodiments, the battery system has a negative electrode made from natural graphite. 18A-18B and 19 show data from additional long-term cycling experiments performed at 40° C., C/3CCCV, using single crystal NMC532 as the positive electrode and natural graphite as the negative electrode. FIG. 18A shows capacity plotted against cycle number. FIG. 18B shows normalized capacity plotted against cycle number. FIG. 19 shows voltage hysteresis (difference between average charge voltage and average discharge voltage) versus number of cycles. Figures 18A-18B and 19 show that the two-electrolyte additive system containing DTD + FEC improves performance over the electrolyte system containing only FEC as an additive, but in which an artificial graphite anode was used. 6-F, suggesting that the performance of this particular artificial graphite negative electrode is superior to this particular natural graphite negative electrode in the two-additive electrolyte system of the present disclosure.

In certain embodiments, the battery system has a natural graphite negative electrode. The use of natural graphite as the negative electrode is important as a cost saving measure over synthetic graphite, which is usually more expensive. Therefore, when cost is a major factor and some performance trade-offs can be made, natural graphite can be a good choice.

LFOs as Additives: In certain embodiments, LFOs are added as electrolyte systems. FIG. 41A summarizes data for coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs. FIG. 41B summarizes fragmentary fade versus upper cutoff voltage data for different electrolyte systems, including a system containing an LFO. FIG. 41C summarizes end-of-charge capacity slip versus upper cut-off voltage data for different electrolyte systems, including systems containing LFOs. FIG. 42A shows a magnified view of FIG. 41A and summarizes data for coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs. FIG. 42B shows a magnified view of 41B and summarizes fragmentary fade versus upper cutoff voltage data for different electrolyte systems, including systems containing LFOs. FIG. 42C shows a magnified view of 41C and summarizes end-of-charge capacity slip versus upper cut-off voltage data for different electrolyte systems, including systems containing LFOs. Addition of LFOs to the control electrolyte significantly improves the UHPC results. When MA is present, 1% LFO dramatically improves the situation compared to 0.5% LFO. CIE/h is about 4×10 ⁻⁵ h ⁻¹ with 1% LFO in control. By comparison, the best electrolyte system without LFO, such as 2% VC+1% DTD in the control, is around 3×10 ⁻⁵ h ⁻¹ .

Figures 43A-43D summarize long-term cycling data for different electrolyte systems, including systems containing LFOs. Long-term cycling results show that the addition of LFO dramatically improves the impedance growth in the tested system, corroborating the UHPC data. In particular, the addition of 1% LFO to control electrolytes and electrolyte systems containing 20% MA improves long-term cycling and impedance.

[Microcalorimetry]
Microcalorimetry measures the heat flow to the cell during operation. Heat flow into the cell has three different effects: (1) ohmic heating, (2) entropy change due to Li inserted in the electrodes, and (3) parasitic reactions (electrolytes with additives, deterioration). Since the test cells contain the same physical design differing only in the electrolyte, the difference in heat flow is mainly due to the difference in parasitic heat flow. Nevertheless, Downie et al. (Journal of the Electrochemical Society, 161, A1782-A1787 (2014)) and Glazier et al.
of the Electrochemical Society, 164(4) A567-A573 (2017)) can be used to extract the parasitic heat flow from the total heat flow. Both of these references are incorporated herein in their entirety. Cells with less parasitic heat flow during cycling have a longer life. By plotting the measured parasitic heat flow as a function of cell voltage, the voltage dependence of the parasitic reaction rate can be observed.

Microcalorimetry procedure: Two cells of each electrolyte were connected to a Maccor charger and inserted into a TAMIII microcalorimeter (TA Instruments, stability ±0.0001°C, accuracy ±1 μW, accuracy ±1 nW) at 40.0°C. bottom. Baseline variation during the experiment did not exceed ±0.5 μW. All specifications and information regarding microcalorimetry calibration, cell connections, and operating procedures can be found in previous publications (eg, Downie et al., ECS Electrochemical Letters 2, A106-A109 (2013)). To ensure a clean and stable SEI, the cell was cycled four times at C/20 rate from 3.0 V to 4.2 V and then cycled four times at 1 mA to investigate performance and parasitic heat flow in different voltage ranges. .0V and different upper cut-off limits. Only one set of heat flow data is presented for each electrolyte since each pair of cells provided nearly identical performance.

The protocol for 1 mA cycling is as follows.
1. Charge to 4.2V, discharge to 4.0V 2. Charge to 4.3V, discharge to 4.0V (repeatedly)
Charge to 3.4.4V, discharge to 4.0V (repeatedly)
6. Charge to 4.2 V, discharge to 4.0 V Additional experimental details are described in Journal of the Electrochemical Society, 164(4) A567-A573 (2017), which is incorporated herein by reference in its entirety. ing.

The experimental data shown in Figures 11-14 used pouch cells with a positive electrode made from single crystal NMC532 and a synthetic graphite negative electrode.
Excluding additives, the electrolyte was (1) 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate, (2 ) 1.2 M LiPF ₆ in ethylene 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate, or (3) 1 in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. .2M _LiPF6 .

FIG. 11 shows experimental data (parasitic heat flow versus voltage) for a calorimetric experiment when charged to 4.2V. 12A and 12B show experimental data (parasitic heat flow versus voltage) for a calorimetric experiment when charged to 4.3V. Since charging to 4.3V was repeated, each plot shows the result of one charge. Figures 13A and 13B show experimental data (parasitic heat flow versus voltage) when charged to 4.4V. Since charging to 4.4V was repeated, each plot shows the result of one charge. Difference plots (FIGS. 11, 12A, 12B, 13A, and 13B) are calculated by taking the heat flow of each electrolyte mixture and subtracting the heat flow produced by the control (2% FEC). . Figure 14 shows a summary of the experimental data reported in Figures 11-13. Table 1 summarizes the data displayed in Figure 14 in tabular form.

Figures 11-14 and Table 1 show that adding DTD to FEC results in lower parasitic heat flow (lower parasitic reaction rate). Figures 11-14 and Table 1 also show that adding MA results in higher parasitic heat flow (higher parasitic reaction rate), but this increase can be mitigated by DTD, which helps reduce the parasitic reaction rate increase from the addition of MA.

LFO as Additive: FIG. 47 shows how charge heat flow relates to parasitic heat flow, charge overpotential, and discharge overpotential. Figures 48a-48F show the results of TAM experiments. The difference plot compares the system with 2% VC + 1% DTD. Figures 48a-48F show that 2% VC + 1DTD is better than 2% FEC + 1DTD. They also show that 1% LFO + 1% VC + 1% FEC is better than 2% VC + 1% DTD above 4.3 V when optimizing for the LFO in the system. Compared to a system with 1% LFO, 1% LFO + 1% VC performs almost as well as 1% LFO + 1% VC + 1% FEC and outperforms 2% VC + 1% DTD at 4.3V. As seen in Figures 50A-50C, the optimum LFO composition is about 1.0%. FIG. 51 shows the average parasitic heat flow as a function of cycle for the best performing cells. A 0.5% LFO with 1% VC + 1% FEC is the best performing system after 4.4V cycling. 2% VC + 1% LFO is very comparable to 2% VC + 1% DTD. Thus, systems with VCs and with or without DTDs are possible.

[Plating experiment]
Plating experiments test the ability to charge at high speed. Fast charging is very important in energy storage when part of a vehicle, although slower charging rates may be acceptable in grid storage. Fast charging is primarily limited by lithium plating on the negative electrode, which leads to safety issues and reduces cycle and calendar life. For this reason, an electrolyte system that allows higher charging rates without plating would be advantageous. Plating experiments were performed to study the plating of the negative electrode. Larger capacity loss indicates more lithium plating.

Plating experiments were performed to test the chargeability of the cells. After EIS measurement, at constant current (C-rate) of 1 C, 1.5 C, and 2.0 C between 2.8 and 4.1 V using Maccor charging system at 20.0 ± 0.1 °C. The cell was charged and discharged. Paired cells were tested at each charge rate to ensure reproducibility. To determine the active lithium loss during cycling, the cells were cycled once at C/20 before and after the high charge rate segment. The upper cutoff voltage was set at 4.1V to minimize electrolyte oxidation on the positive electrode and to ensure that the cells never had a fully loaded negative electrode, which occurs in these cells at 4.4V. All pouch cells were cycled with external clamps to eliminate the effects of small amounts of gas that may be generated during cycling. The cells were stopped after about 350 hours of cycling or after the capacity loss reached 20%.

Two-electrolyte system with FEC or VC as additive: In certain embodiments, a two-additive electrolyte system with a concentration of about 0.25-6% for each additive forms part of the battery system. FIG. 22 shows experimental data for plating experiments of different battery systems at different current charging rates. Figure 22 shows that the addition of DTD does not significantly increase the maximum current at which plating occurs. For example, the slow capacity loss of an electrolyte system consisting of two additives, i.e., 2% FEC + 1% DTD, is reduced at 1C, 1.5C, and 2C compared to an electrolyte system consisting of a single additive, 2% FEC. do. Similarly, Figure 22 shows that the slow capacity loss of an electrolyte system consisting of two additives, 1% FEC + 1% DTD, at 1C and 1.5C compared to an electrolyte system consisting of a single additive, 2% FEC. It shows that the This is only slightly higher at 2C.

FIG. 23 shows experimental data from the plating test where the charging current increased every 30 cycles. A large capacity loss rate indicates lithium plating. At a charging current of 2C, all cells began to plate lithium. However, cells with DTDs do not lose much capacity during plating. This indicates that the amount of plating in cells with DTD is less than in cells without DTD. In addition to DTD, other sulfur-containing compounds can function similarly to reduce plating.

FIG. 24 shows experimental data results of peak capacity as a function of cycle number for different electrolyte systems. DTD performed better than MMDS in maintaining the peak capacity of the two-additive electrolyte system when DTD and MMDS were combined with VC.

Methyl Acetate as Electrolyte Solvent: According to certain embodiments, methyl acetate is used in concentrations up to 60% by weight as a solvent to reduce plating. Figures 27-34 show the effect of using MA as a solvent in the presence of different electrolyte systems. FIG. 27 shows the results of plating experiments to determine the effect of the presence of MA as a solvent and DTD as an additive on cell impedance. The electrolyte systems tested included 2% additives (VC, FEC, and PES) in electrolytes with 0%, 20%, and 40% MA. The remaining electrolyte at 0% MA is 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate. The remaining electrolyte at 20% MA is 1.2 M _LiPF6 in 24% ethylene carbonate and 56% ethyl methyl carbonate. The remaining electrolyte at 40% MA is 1.2 M _LiPF6 in 18% ethylene carbonate and 42% ethyl methyl carbonate. FIG. 28 is an enlarged view of certain data shown in FIG. 27 with low low speed capacity loss.

In Figures 27 and 28, higher capacity loss indicates more lithium plating. Figures 27 and 28 show that the presence of MA reduces the slow capacity loss even at 2C charge rate. Electrolyte systems containing 20% or 40% MA are therefore good candidates for use in fast charging applications such as energy storage in vehicles that may be exposed to fast charging current rates. .

Figures 29, 30, and 31 show the results of experimental data for electrolyte systems containing FEC as an additive. Different datasets include DTDs and/or MAs, as indicated in the figure legends. Figures 29, 30, and 31 show that the addition of MA to one-additive or two-additive electrolyte systems with FEC enables higher charging rates, including up to 2C, without significant plating. It is shown that.

Similarly, Figures 32, 33 and 34 show experimental data results for electrolyte systems containing VC as an additive. Different datasets include DTDs and/or MAs, as indicated in the figure legends. Figures 32, 33, and 34 show that the addition of MA to a one-additive or two-additive electrolyte system with VC enables higher charging rates, including up to 2C, without significant plating. It is shown that.

LFOs as electrolyte additives: Figures 44A-44D summarize long-term cycling data under fast charging for different electrolyte systems, including systems containing LFOs. As can be seen from the experimental data, the presence of MA reduces the amount of plating. Additionally, the LFO reduces the possibility of Li plating during fast charging. For example, in FIG. 44A, an electrolyte system with 20% MA+1% LFO exhibits significantly less normalized discharge capacity loss than another system with either less MA or less LFO. Loss of normalized discharge capacity represents plating.

[Gas volume measurement]
A forming process is carried out before the cells are used in their intended application, such as grid storage or energy storage in vehicles such as electric vehicles. During formation, the cell undergoes precisely controlled charge and discharge cycles, which are intended to activate the electrodes and electrolyte for use in the intended application. Gas is evolved during formation. If a sufficient amount of gas is generated (depending on the specific tolerances allowed by the cell and cell package), it may be necessary to release the gas after the forming process and prior to use in the application. do not have. This usually requires an additional step of breaking the seal and then resealing. Although these steps are common to many battery systems, it is desirable to eliminate them if possible by choosing systems that produce less gas.

Gas volume experiments were recommended as follows. Ex-situ (static) gas measurements were used to measure gas evolution during formation and cycling. Measurements were made using Archimedes' principle with the cell suspended from a balance while immersed in the liquid. The change in weight of the cell suspended in the fluid before and after the test is directly related to the change in volume due to the change in buoyancy. Changes in the mass Am of a cell suspended in a fluid of density p are related to changes in the cell volume Δν by Δν=Am/p.

Two-electrolyte system with FEC or VC as additive: In certain embodiments, a two-additive electrolyte system with a concentration of about 0.25-6% for each additive forms part of the battery system. Figure 20 shows the results of a gas generation experiment in which the amount of gas generated was measured according to the procedure described above. Figure 20 shows that systems without DTD typically perform better, e.g., systems containing only 2% FEC as an additive perform better than 1% FEC + 1% DTD and 2% FEC + 1% DTD. showing. That is, DTD increases gas volume production during formation, and when DTD is used as an additive due to its desirable properties when combined with other additives such as VC and FEC, the system will Mechanisms for safely handling the gases generated by the DTD should be included, such as post-formation outgassing as discussed in . FIG. 20 shows that a two-additive electrolyte system containing MMDS and PES or FEC does not produce more (if any) additional gas than when 2% PES or FEC is the only additive. there is

Methyl Acetate as Electrolyte Solvent: According to certain embodiments, methyl acetate is used in concentrations up to 60% by weight as a solvent to reduce plating. FIG. 25 shows the results of gas generation experiments to determine the effect of the presence of MA as a solvent and DTD as an additive on the formed gas generated. The electrolyte systems tested included 2% additives (VC, FEC, and PES) in electrolytes with 0%, 20%, and 40% MA. The remaining electrolyte at 0% MA is 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate. The remaining electrolyte at 20% MA is 1.2 M _LiPF6 in 24% ethylene carbonate and 56% ethyl methyl carbonate. The remaining electrolyte at 40% MA is 1.2 M _LiPF6 in 18% ethylene carbonate and 42% ethyl methyl carbonate.

FIG. 25 shows that in a two-additive electrolyte system containing VC or FEC with DTD, increasing the amount of gas with the addition of MA does not change much with increasing amount of MA. That is, when the DTD is part of a two-additive electrolyte system, the critical amount of gas generated is less compared to a one-additive electrolyte system with only VC or FEC.
In-situ gas volume measurement

Figures 45A and 45B summarize the results of in-situ gas experiments at 40°C. Cells with LFO but no MA show less gassing during the hold segment of these tests.
cell impedance

The two-additive electrolyte system and novel battery system disclosed herein have low cell impedance. Minimizing cell impedance is desirable because cell impedance reduces the energy efficiency of the cell. Conversely, lower impedance results in faster charging speeds and higher energy efficiency.

Cell impedance was measured using electrochemical impedance spectroscopy (EIS). Pouch cells used single crystal NMC532 positive electrodes and synthetic negative electrodes, unless otherwise specified, and EIS measurements were made after formation. The cell was charged or discharged to 3.80V before moving the cell to a temperature box of 10.0±0.1°C. AC impedance spectra were collected at 10.0±0.1° C. with a signal amplitude of 10 mV, from 100 kHz to 10 mHz with a resolution of 10 points per decade. From the measured AC impedance, the charge transfer resistance (R _ct ) was calculated and plotted.

Two-electrolyte system with FEC or VC as additive: In certain embodiments, a two-additive electrolyte system with a concentration of about 0.25-6% for each additive forms part of the battery system. FIG. 21 shows experimental data for cell charge transfer impedance experiments of two-additive electrolyte systems consisting of 1% DTD with 1% or 2% PES, FEC, or VC. FIG. 21 shows that these two-additive electrolyte systems at 1% DTD with 1% or 2% PES, FEC, or VC do not significantly increase cell charge transfer impedance. Specifically, systems with 1% DTD with 1% VC, 1% DTD with 2% VC, 1% DTD with 1% FEC, and 1% DTD with 2% FEC are single additive It exhibits a cell impedance value similar to the cell charge transfer impedance seen in the system. Therefore, these novel two-additive electrolyte systems do not sacrifice critical charge transfer impedance performance by including a DTD.

Methyl Acetate as Electrolyte Solvent: According to certain embodiments, methyl acetate is used in concentrations up to 60% by weight as a solvent to reduce plating. FIG. 26 shows the results of cell charge transfer impedance experiments for electrolyte systems consisting of one-additive and two-additive systems with MA as one of the solvents. The additive electrolyte system tested was additive VC, FEC, without and without 1% DTD to show the effect of DTD and MA on the electrolyte system in electrolyte solvents with 0%, 20%, and 40% MA. , and PES at 2%. The electrolyte at 0% MA is 1.2 M _LiPF6 in 30% ethylene carbonate and 70% ethyl methyl carbonate. The remaining electrolyte at 20% MA is 1.2 M _LiPF6 in 24% ethylene carbonate and 56% ethyl methyl carbonate. The remaining electrolyte at 40% MA is 1.2 M _LiPF6 in 18% ethylene carbonate and 42% ethyl methyl carbonate. FIG. 26 shows that DTD produces only a slight increase in charge transfer impedance. Furthermore, in two-additive electrolyte systems containing VC or FEC with DTD, the addition of MA lowers the cell charge transfer impedance. At 40% MA solvent, the VC+DTD and FEC+DTD systems showed reduced charge transfer impedance from the corresponding systems without DTD and MA as solvent. In the PES+DTD2 additive electrolyte system, MA also lowered the charge transfer impedance of the system.

The above disclosure is not intended to limit the present disclosure to the precise forms of use disclosed or to the particular field. Thus, it is contemplated that various alternative embodiments and/or modifications to the present disclosure, whether expressly stated or implied herein, are possible in light of the present disclosure. Having thus described embodiments of the present disclosure, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Accordingly, the disclosure is limited only by the claims. References to additives in the specification generally refer to active additives unless otherwise specified in the specification.

In the foregoing specification, the disclosure has been described with reference to specific embodiments. However, as will be appreciated by those skilled in the art, the various embodiments disclosed herein can be modified or implemented in various other ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be considered exemplary and is for the purpose of teaching those skilled in the art how to make and use the various embodiments of the disclosed battery system. It is to be understood that the forms of disclosure shown and described herein are to be construed as representative embodiments. Equivalent elements or materials may be substituted for those typically shown and described herein. Also, certain features of the disclosure may be utilized independently of the use of other features, as would be apparent to one of ordinary skill in the art after having the benefit of this description of the disclosure. The terms "including", "comprising", "incorporating", "consisting of", "have" and "have" are used to describe and claim this disclosure. Phrases such as "is" are intended to be interpreted inclusively, ie, there may also be items, ingredients, or elements not explicitly listed. References to the singular should be construed to also refer to the plural. References to "about" or "approximately" should be construed to mean plus or minus 10%. Similarly, reference to any percentage of an additive should be construed to mean plus or minus 10%.

Moreover, the various embodiments disclosed herein are to be construed in an illustrative and explanatory sense, and not as limiting the present disclosure in any way. All coupling references (e.g., mounting, securing, coupling, connecting, etc.) are used only to assist the reader's understanding of the present disclosure, particularly the location of the systems and/or methods disclosed herein, It is not intended to form any limitation as to orientation or use. References to coupling, if any, should therefore be interpreted broadly. Also, such coupling references do not necessarily imply that the two elements are directly connected to each other.

In addition, terms such as "first", "second", "tertiary", "primary", "secondary", "principal", or any other regular and/or numerical terms, but not these All numerical terms, including but not limited to, should also be construed as identifiers only, to aid the reader's understanding of the various elements, embodiments, variations, and/or modifications of the present disclosure; , embodiments, variations and/or modifications, particularly as to the order or priority of any element, embodiment, variation and/or modification.

Also, one or more of the elements shown in a drawing/figure may be implemented in a more divided or integrated manner, or in certain cases omitted or omitted, as is useful for a particular application. It can also be removed as inoperable.

U.S. Patent Application Publication No. 2017/0025706

J. C. Burns et al. , Journal of the Electrochemical Society, 160, A1451 (2013)

Missing number

Figures 50A-50C summarize experimental average parasitic heat flow data as a function of cycle number for different electrolyte systems.
FIG. 10 summarizes experimental average parasitic heat flow data as a function of cycle number for electrolyte systems containing 2% VC + 1% DTD and 2% FEC + 1% DTD.

Missing number Guangzhou Tinci Materials Technology Co., Ltd. , Ltd. and Shenzhen Capchem Technology Co. , Ltd. 1 summarizes experimental data of mass change due to air exposure of LFOs over time.

Claims (19)

a lithium salt, a first non-aqueous solvent, and an additive mixture comprising a first active additive of lithium difluorophosphate and a second active additive of either fluoroethylene carbonate or vinylene carbonate; Non-aqueous electrolyte for lithium-ion batteries. 2. The non-aqueous electrolyte of claim 1, wherein the concentration of said first active additive is in the range of 0.25-wt%. 3. The non-aqueous electrolyte of claim 2, wherein said concentration of said second active additive is in the range of 0.25-6% by weight. 4. The non-aqueous electrolyte of claim 3, wherein said non-aqueous electrolyte does not contain a third active additive. 5. The non-aqueous electrolyte of claim 4, wherein said first non-aqueous solvent is a carbonate solvent. 6. The non-aqueous electrolyte of claim 5, further comprising a second non-aqueous solvent of methyl acetate. 7. The non-aqueous electrolyte of claim 6, wherein said second active additive is vinylene carbonate. 4. The non-aqueous electrolyte of claim 3, further comprising a second non-aqueous solvent of methyl acetate. a negative electrode;
a positive electrode;
a non-aqueous electrolyte comprising lithium ions dissolved in a first non-aqueous solvent and an additive mixture;
The additive mixture is
a first active additive of lithium difluorophosphate;
and a second active additive of either fluoroethylene carbonate or vinylene carbonate. 10. The lithium ion battery of claim 9, excluding active additives of tris(trimethylsilyl) phosphate and tris(trimethylsilyl) phosphite of 0.25% or more by weight. 10. The lithium ion battery of claim 9, wherein the concentration of said first active additive is in the range of 0.25-6% by weight. 12. The lithium ion battery of claim 11, wherein the concentration of said second active additive is in the range of 0.25-6% by weight. 13. The lithium ion battery of claim 12, wherein said non-aqueous electrolyte does not contain a third active additive. 14. The lithium ion battery of claim 13, wherein said first non-aqueous solvent is a carbonate solvent. 15. The lithium ion battery of Claim 14, further comprising a second non-aqueous solvent of methyl acetate. 16. The lithium ion battery of claim 15, wherein the positive electrode comprises either NMC532 or NMC622 having a particle size greater than 0.5 microns. 17. The lithium ion battery of claim 16, wherein said positive electrode is coated with aluminum oxide or titanium dioxide. 18. The lithium ion battery of Claim 17, further comprising a second non-aqueous solvent of methyl acetate. a negative electrode;
a positive electrode comprising an NMC having micrometer-scale particles;
a non-aqueous electrolyte comprising lithium ions dissolved in a first non-aqueous solvent and an additive mixture;
The additive mixture is
a first active additive, either fluoroethylene carbonate or vinylene carbonate;
1,3,2-dioxathiolane-2,2-dioxide, another sulfur-containing additive, or a second active additive, either lithium difluorophosphate.

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