KR20230008253A - Novel battery systems based on lithium difluorophosphate - Google Patents

Abstract

Non-aqueous electrolytes for lithium ion batteries include lithium salts; a first non-aqueous solvent; and an additive mixture comprising a first operative additive of lithium difluorophosphate and a second operative additive of fluoro ethylene carbonate or vinylene carbonate ( additive mixture); A lithium-ion battery has a negative electrode; a positive electrode comprising NMC having micrometer-sized particles; and a non-aqueous electrolyte comprising lithium ions dissolved in a first non-aqueous solvent and an additive mixture, wherein the additive mixture comprises: a first working additive of fluoro ethylene carbonate or vinylene carbonate; and a second operational additive of 1,3,2-dioxathiolane-2,2-dioxide, another sulfur-containing additive, or lithium difluorophosphate.

Description

Novel battery system based on lithium difluorophosphate {NOVEL BATTERY SYSTEMS BASED ON LITHIUM DIFLUOROPHOSPHATE}

The present invention relates to rechargeable battery systems, and more specifically to the chemistry of such systems, including operative electrolyte additives and electrodes for improving the properties of rechargeable lithium-ion battery systems.

Rechargeable batteries are an essential component of energy storage systems for electric vehicles and grid storage (eg, back-up power as part of a microgrid in case of a power outage, etc.). Lithium-ion based batteries are a common type of rechargeable battery.

Electrolyte additives have been shown to work and increase the life and performance of lithium-ion-based batteries. For example, in J. C. Burns et al., Journal of the Electrochemical Society, 160, A1451 (2013), five proprietary, undisclosed electrolyte additives were shown to increase cycle life compared to electrolyte systems with only or no additives. . Other studies have focused on improving performance from electrolyte systems containing 3 or 4 additives described in US Patent 2017/0025706. However, researchers generally do not understand the interactions between the electrolyte and the different additives that allow them to work synergistically with specific anodes and cathodes. Thus, the composition of a particular system's additive blend is often based on trial and error and cannot be predicted in advance.

Prior research has not identified a two-additive electrolyte system that can be coupled to a lithium-ion battery system to obtain a robust system with properties sufficient for grid or automotive applications. As discussed in US Patent 2017/0025706, the studied two-additive systems (e.g., 2% VC + 1% allyl methanesulfonate and 2% PES + 1% TTSPi) generally have three- and four It outperformed the two-additive electrolyte system {see, for example, US Patent 2017/0025706 in Tables 1 and 2}. US Patent 2017/0025706 teaches that three compounds, often tris(-trimethyl-silyl)-phosphate (TTSP) or tris(-trimethyl-silyl)-phosphite (TTSPi), are used to make robust lithium-ion battery systems. A concentration of 0.25-3% by weight is disclosed as required. {See, for example, US patent U.S. See 2017/0025706, page 72}. However, since additives can be expensive and difficult to incorporate into Li-ion batteries at manufacturing scale, there is a need for simpler yet more effective battery systems with fewer additives.

The present disclosure includes a novel battery system with a lower working electrolyte electrolyte that can be used in different energy storage applications, such as vehicles and grid storage. More specifically, the present disclosure includes two-additive electrolyte systems that improve the performance and life of Li-ion batteries, while reducing the cost of other systems that rely on more additives. The present disclosure also discloses effective anodes and cathodes that work with the disclosed two-additive electrolyte systems to provide further systematic improvements.

The disclosed two-acting additive electrolyte system comprises: 1) vinylene carbonate (VC) combined with 1,3,2-dioxathiolane-2,2-dioxide (DTD, also known as ethylene sulfate) or other sulfur-containing additives (e.g. methylene methane disulfonate, trimethylene sulfate, 3-hydroxypropanesulfonic acid γ-sultone, glycol sulfite or other sulfur-containing additives), 2) DTD or other sulfur-containing additives fluoro ethylene carbonate (FEC) in combination with; and 3) prop-1-ene-1,3-sultone (PES) in combination with other sulfur-containing additives. Also, since VC and FEC provide similar improvements (and are believed to function similarly), a mixture of VC and FEC can be considered a single working electrolyte. That is, other disclosed two-acting additive electrolyte systems include a mixture of VC and FEC combined with DTD or other sulfur-containing additives. When used as part of a larger battery system (including electrolyte, electrolyte solvent, positive and negative electrodes), these two-acting additive electrolyte systems produce desirable properties for energy storage applications, including vehicle and grid applications.

More specifically, a lithium salt dissolved in a lithium nickel manganese cobalt oxide (NMC) positive electrode, a graphite negative electrode, an organic or non-aqueous solvent, methyl acetate (MA) and two additives are included in the battery system with desirable properties for different applications. can form The electrolyte solvent may be the following solvents alone or in combination: ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl acetate, propylene carbonate, dimethyl carbonate, diethyl carbonate, other carbonate solvents (cyclic or non-cyclic) , other organic solvents, and/or other non-aqueous solvents. The solvent is present at a concentration greater than the additive, typically greater than 6% by weight. Solvents can be mixed with the disclosed two-additive pairs (e.g., VC and DTD, FEC and DTD, mixtures of VC and FEC and DTD, or other combinations) to form battery systems with desirable properties for different applications. can The anode may be coated with a material such as aluminum oxide (Al2O3), titanium dioxide (TiO2), or another coating. Also, as a cost saving, the negative electrode can be formed from natural graphite, but depending on the price structure, in certain cases, artificial graphite is cheaper than natural graphite.

The disclosure herein is supported by experimental data demonstrating the symbiotic properties of the two-additive electrolyte system and selected electrodes. An exemplary battery system includes two additives (eg, FEC, VC, or PES and DTD or other sulfur-based additive), a graphite negative electrode (natural graphite or artificial synthetic graphite), a NMC positive electrode, a lithium electrolyte (eg, chemical formed from a lithium salt such as lithium hexafluorophosphate having the composition LiPF ₆ ), and an organic or non-aqueous solvent. A lithium-ion battery includes a negative electrode, a positive electrode comprising NMC having micrometer-scale particles, and a non-aqueous electrolyte comprising lithium ions dissolved in a first non-aqueous solvent, and a first layer of fluoroethylene carbonate or vinylene carbonate. and an additive mixture having a operative additive and a second operative additive of 1,3,2-dioxathiolane-2,2-dioxide, another sulfur-containing additive, or lithium difluorophosphate.

1 is a schematic diagram of a vehicle containing a battery storage system.
2 is a schematic diagram of an exemplary battery storage system.
3 is a schematic diagram of a lithium-ion, battery-cell system.
Figures 4a-j show typical experimental data collected during ultra-precision charging experiments of battery systems with different electrolyte compositions.
4A plots time-normalized Coulombic Inefficiency (CIE/h) versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC + 1% DTD.
4B plots Coulombic efficiency (CE) versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC + 1% DTD.
FIG. 4C shows the plotted charge endpoint capacity versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC + 1% DTD.
4D plots discharge capacity versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC + 1% DTD.
4E shows the change in open circuit voltage versus cycle number for electrolyte systems containing 1% DTD, 2% VC, and 2% VC + 1% DTD.
4F plots time-normalized coulombic efficiency per hour (CIE/h) versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC + 1% DTD.
4G plots Coulombic efficiency (CE) versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC + 1% DTD.
FIG. 4H plots capacity versus cycle number of charge endpoints plotted for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC + 1% DTD.
4I plots discharge capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, and 2% FEC + 1% DTD.
4J shows the difference between average charge voltage and average charge voltage (Delta V) for electrolyte systems including 1% DTD, 2% FEC, and 2% FEC + 1% DTD.
Figures 5a-c show the average of the last three cycles of the data shown in Figure 4 and show more per hour for the combination of FEC + DTD and VC + DTD compared to any single additive of FEC, VC, or DTD. It exhibits low coulombic inefficiency and lower partial slippage.
FIG. 5A shows the average Coulombic inefficiency per hour for the last three cycles of data generated during the experiment shown in FIG. 4 .
FIG. 5B shows the average partial slippage for the last three cycles of data generated during the experiment shown in FIG. 4 .
FIG. 5C shows the average partial fade over the last three cycles of data generated during the experiment shown in FIG. 4 .
Figures 6a-f show data from typical experiments studying long-term cycling at 40 °C, C/3 CCCV, demonstrating the benefits of including DTD as an additive to electrolyte systems containing VC or FEC.
6A shows capacity versus cycles for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC and 2% VC + 1% DTD, cycling between 3.0 V and 4.2 V. show the number
6B shows normalized capacities for electrolyte systems comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC and 2% VC + 1% DTD, cycling between 3.0 V and 4.2 V. shows the number of cycles.
6C shows voltage hysteresis for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.2 V. (difference between average charge voltage and average charge voltage) versus number of cycles.
6D shows capacity versus capacity for electrolyte systems comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.2 V. Shows the number of cycles.
FIG. 6E shows normalized plots for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.2 V. It plots capacity versus cycle number.
6F shows voltage hysteresis for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.2 V. (difference between average charge voltage and average charge voltage) versus number of cycles.
Figures 7a-f show data from typical experiments studying long-term cycling at 40 °C, C/3 CCCV, demonstrating the benefits of including DTD as an additive to electrolyte systems containing VC or FEC.
7A shows capacity versus capacity for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.3 V. Shows the number of cycles.
FIG. 7B shows normalized plots for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.3 V. It plots capacity versus cycle number.
7C shows voltage hysteresis for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.3 V. (difference between average charge voltage and average charge voltage) versus number of cycles.
7D shows capacity versus capacity for electrolyte systems comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.3 V. Shows the number of cycles.
FIG. 7e shows normalized plots for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.3 V. It plots capacity versus cycle number.
7F shows voltage hysteresis for an electrolyte system comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, cycling between 3.0 V and 4.3 V. (difference between average charge voltage and average charge voltage) versus number of cycles.
8A-I depict typical experimental data during cycling experiments for electrolyte compositions according to certain aspects of the present disclosure.
8A shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Peak capacity versus cycle number is plotted for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8B shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Normalized capacity versus cycle number is shown for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8C shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Voltage hysteresis (difference between average charge voltage and average charge voltage) is shown for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8D shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Peak capacity versus cycle number is plotted for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8E shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Normalized capacity versus cycle number is shown for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8F shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Voltage hysteresis (difference between average charge voltage and average charge voltage) is shown for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8G shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Peak capacity versus cycle number is plotted for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8H shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Normalized capacity versus cycle number is shown for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
8I shows 2% FEC, 1% FEC + 1% DTD, 2% FEC cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. Voltage hysteresis (difference between average charge voltage and average charge voltage) is shown for electrolyte systems containing + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS.
9a-9d and 9f-9i are data collected during ultra-high precision charging experiments showing that methyl acetate can be added to electrolyte systems containing VC or FEC with DTD to increase electrolyte conductivity without significantly sacrificing life. Typical experimental data are shown. Increasing conductivity and decreasing viscosity are important for certain applications requiring faster fill rates.
9A depicts general experimental data showing coulombic efficiency (CE) versus cycle number for an electrolyte system according to certain aspects of the present disclosure.
FIG. 9B depicts typical experimental data showing plotted charge endpoint capacity versus cycle number for an electrolyte system according to certain aspects of the present disclosure.
9C depicts typical experimental data showing discharge capacity versus cycle number for an electrolyte system according to certain aspects of the present disclosure.
FIG. 9D depicts typical experimental data showing the difference between average charge voltage and average charge voltage (delta V) versus number of cycles at open circuit voltage for an electrolyte system according to certain aspects of the present disclosure.
9F depicts general experimental data showing coulombic efficiency (CE) versus number of cycles for an electrolyte system according to certain aspects of the present disclosure.
9G depicts typical experimental data showing plotted capacity of charge endpoint versus number of cycles for an electrolyte system according to certain aspects of the present disclosure.
9H depicts general experimental data showing discharge capacity versus number of cycles for an electrolyte system according to certain aspects of the present disclosure.
FIG. 9I depicts general experimental data showing average charge voltage and difference between average charge voltage (delta V) versus number of cycles for an electrolyte system according to certain aspects of the present disclosure.
10A-C are plots summarizing the experimental data and demonstrating that electrolyte additives VC and FEC alone and in the presence of DTD still provide acceptable performance as the MA content increases.
10A is a plot summarizing the experimental data of time-normalized CIE as a function of the content of MA.
10B is a plot summarizing the experimental data of time-normalized partial fade as a function of the content of MA.
10C is a plot summarizing experimental data of time-normalized partial fill endpoint capacity slippage as a function of content of MA.
Figure 11 shows the parasitic heat flow and the parasitic heat flow of a cell containing 2% FEC + 0% MA as a function of voltage for different electrolyte compositions containing FEC within the voltage range of 4.0 V to 4.2 V. It is a plot summarizing the experimental data of the difference in .
12a-b show the parasitic heat flow and parasitic heat flow of a cell containing 2% FEC + 0% MA as a function of voltage for different electrolyte compositions containing FEC within the voltage range of 4.0 V to 4.3 V. A plot summarizing the experimental data of the difference between flows. Figure 12a shows the results of the first cycle with 4.3 V. 12B shows the results of the second cycle.
13a-b show parasitic heat flow and parasitic heat flow of a cell containing 2% FEC + 0% MA as a function of voltage for different electrolyte compositions containing FEC within the voltage range of 4.0 V to 4.4 V. A plot summarizing the experimental data of the difference between flows. Figure 13a shows the results of the first cycle to 4.4 V. 13B shows the results of the second cycle.
14 is a plot summarizing experimental parasitic heat flow data including the data shown in FIGS. 11-13.
15a-f are plots of experimental data taken at 20 °C for capacity, normalized capacity and voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for electrolyte systems containing FEC.
15A is a plot of experimental data taken at 20 °C versus capacity versus cycle number for an electrolyte system containing an FEC with cycling below 4.2 V.
FIG. 15B is a plot of experimental data taken at 20° C. versus normalized capacity versus cycle number for an electrolyte system containing an FEC with cycling below 4.2 V. FIG.
15C is a plot of experimental data taken at 20 °C versus voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing an FEC with cycling of 4.2 V or less.
15D is a plot of experimental data taken at 20 °C versus capacity versus cycle number for electrolyte systems containing FEC with cycling below 4.3 V.
FIG. 15E is a plot of experimental data taken at 20° C. versus normalized capacity versus cycle number for an electrolyte system containing an FEC with cycling of 4.3 V or less.
15F is a plot of experimental data taken at 20 °C versus voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing an FEC with cycling of 4.3 V or less.
16a-f are plots of experimental data taken at 40 °C for capacity, normalized capacity, and voltage hysteresis for electrolyte systems containing FEC.
16A is a plot of experimental data taken at 40 °C versus capacity versus cycle number for an electrolyte system containing an FEC with cycling below 4.2 V.
FIG. 16B is a plot of experimental data taken at 40° C. versus normalized capacity versus cycle number for an electrolyte system containing an FEC with cycling below 4.2 V. FIG.
16C is a plot of experimental data taken at 40 °C versus voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing an FEC with cycling of 4.2 V or less.
16D is a plot of experimental data taken at 40 °C versus capacity versus cycle number for electrolyte systems containing FEC with cycling below 4.3 V.
FIG. 16E is a plot of experimental data taken at 40° C. versus normalized capacity versus cycle number for an electrolyte system containing an FEC with cycling below 4.3 V. FIG.
16F is a plot of experimental data taken at 40 °C versus voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing an FEC with cycling of 4.3 V or less.
17A-F are plots of experimental data of capacity, normalized capacity, and voltage hysteresis for electrolyte systems containing FEC, VC, and/or DTD.
17A is a plot of experimental data for capacity versus cycle number for an electrolyte system containing FEC and/or DTD with cycling less than or equal to 4.3 V.
17B is a plot of experimental data for normalized capacity versus cycle number for electrolyte systems containing FEC and/or DTD with cycling below 4.3 V.
17C is a plot of experimental data for voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for electrolyte systems containing FEC and/or DTD with cycling of 4.3 V or less.
17D is a plot of experimental data for capacity versus cycle number for an electrolyte system containing VC and/or DTD with cycling of 4.3 V or less.
17E is a plot of experimental data for normalized capacity versus cycle number for an electrolyte system containing VC and/or DTD with cycling of 4.3 V or less.
17F is a plot of experimental data for voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for electrolyte systems containing VC and/or DTD with cycling of 4.3 V or less.
18A is a plot of experimental data for capacity versus cycle number for an electrolyte system containing an FEC with cycling of 4.3 V or less.
18B is a plot of experimental data for normalized capacity versus cycle number for an electrolyte system containing an FEC with cycling of 4.3 V or less.
19 is a plot of experimental data for voltage hysteresis (difference between average charge voltage and average charge voltage) versus number of cycles for an electrolyte system containing an FEC with cycling of 4.3 V or less.
20 is a plot summarizing experimental data of the volume of forming gas produced during cell formation for different electrolyte systems.
21 is a plot summarizing experimental data of charge transfer impedance for different electrolyte systems.
22 is a plot summarizing experimental data measuring low rate capacity loss for different electrolyte systems after the cell was charged at three different charge rates at 20° C. for 30 cycles.
23 is a plot summarizing experimental data summarizing peak capacity as a function of cycle number for different electrolyte systems used in cells charged at different charge rates at 20 °C.
24 is a plot summarizing experimental data summarizing peak capacity as a function of cycle number for different electrolyte systems used in cells charged at different charge rates at 20 °C.
25 is a plot summarizing experimental data of the volume of forming gas for different additives at varying concentrations of MA solvent.
26 is a plot summarizing experimental data of charge transfer impedance for different additives at varying concentrations of MA solvent.
27 is a plot summarizing experimental data of slow capacity loss for different electrolyte compositions and after charging at 1, 1.5, and 2C for 30 cycles at 20°C.
28 is an enlarged view of the specific experimental data shown in FIG. 27;
29 summarizes the experimental data of delta V (difference between average charge voltage and average charge voltage) as a function of cycle number for electrolyte systems containing FEC.
30 summarizes experimental data of peak capacity as a function of cycle number for electrolyte systems containing FEC.
31 summarizes experimental data of energy hysteresis as a function of cycle number for electrolyte systems containing FEC.
32 summarizes experimental data of delta V (difference between average charge voltage and average charge voltage) as a function of cycle number for electrolyte systems containing VC.
33 summarizes experimental data of peak capacity as a function of cycle number for electrolyte systems containing VC.
34 summarizes experimental data of energy hysteresis as a function of cycle number for electrolyte systems containing VC.
Figures 35a-d summarize the experimental data of an electrolyte system with a cathode of artificial graphite and an anode of NMC532.
35A summarizes experimental impedance data plotting the negative of the imaginary portion of impedance against the real portion of impedance for different electrolyte systems, including systems containing an LFO.
35B summarizes experimental impedance data plotting the negative of the imaginary part of the impedance against the real part of the impedance for different electrolyte systems, including systems containing VC, PES or LFO.
35C summarizes experimental impedance data plotting the negative of the imaginary portion of impedance against the real portion of impedance for different electrolyte systems, including systems containing FEC, DTD, or LFO.
35D summarizes experimental impedance data of different electrolyte systems containing VC, FEC, DTD, PES, or LFO, the anode of NMC532, and the cathode of artificial graphite.
36 summarizes experimental data of different electrolyte systems containing VC, FEC, DTD, PES, or LFO.
37a-f summarizes experimental storage data for different electrolyte systems containing LFOs compared to controls without LFOs.
37A summarizes voltage-drop data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 4.4V.
37B summarizes voltage-drop data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 2.5V.
37C summarizes volume change data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems have been stored at 60° C. for 500 hours at 4.4V.
37D summarizes volume change data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems have been stored at 60° C. for 500 hours at 2.5V.
37E summarizes impedance data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 4.4V.
37F summarizes impedance data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 2.5V.
38A-F summarizes experimental storage data for different electrolyte systems containing LFOs compared to controls without LFOs.
38A summarizes voltage-drop data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 4.4V.
38B summarizes voltage-drop data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 2.5V.
38C summarizes volume change data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems have been stored at 60° C. for 500 hours at 4.4V.
38D summarizes volume change data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems have been stored at 60° C. for 500 hours at 2.5V.
38E summarizes impedance data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 4.4V.
38F summarizes impedance data for different electrolyte systems containing LFOs compared to controls without LFOs after the systems were stored at 60° C. for 500 hours at 2.5V.
Figures 39a-f summarize experimental data of different electrolyte systems containing LFOs compared to controls without LFOs.
39A summarizes Coulombic Efficiency (CE) versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.1V.
39B summarizes the change in voltage versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.1V.
39C summarizes the plotted charge endpoint capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.1V.
39D summarizes the normalized discharge capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.1V.
39E summarizes Coulombic Efficiency (CE) versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.2V.
39F summarizes the change in voltage versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.2V.
39G summarizes the plotted charge endpoint capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.2V.
39H summarizes the normalized discharge capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.2V.
Figures 40a-f summarize experimental data of different electrolyte systems containing LFOs compared to controls without LFOs.
40A summarizes Coulombic Efficiency (CE) versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.3V.
40B summarizes open circuit voltage versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.3V.
40C summarizes the plotted charge endpoint capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.3V.
40D summarizes normalized discharge capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.3V.
40E summarizes Coulombic Efficiency (CE) versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.4V.
40F summarizes open circuit voltage versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.4V.
40G summarizes the plotted charge endpoint capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.4V.
40H summarizes the normalized discharge capacity versus cycle number data for an electrolyte system including a system containing an LFO with cycling up to 4.4V.
41A summarizes data of Coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
FIG. 41B summarizes data of partial fade versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
41C summarizes data of charge endpoint capacity slippage versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
FIG. 42A shows an enlarged view of FIG. 41A and summarizes data of Coulombic inefficiency versus upper limit cut-off voltage for different electrolyte systems, including systems containing LFOs.
FIG. 42B shows an enlarged view of FIG. 41B and summarizes data of partial fade versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
FIG. 42C shows an enlarged view of FIG. 41C and summarizes data of charge endpoint capacity slippage versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
Figures 43a-d summarize long-term cycling data for different electrolyte systems, including systems containing LFOs.
FIG. 43A summarizes normalized discharge capacity data for different electrolyte systems, including systems containing LFOs where cycling occurs at 40° C.
43B summarizes average-charge voltage data for different electrolyte systems, including systems containing LFOs where cycling occurs at 40 °C.
43C summarizes the normalized discharge capacity data for different electrolyte systems, including systems containing LFOs where cycling occurs at 20 °C.
43D summarizes average-charge voltage data for different electrolyte systems, including systems containing LFOs where cycling occurs at 20 °C.
Figures 44a-d summarize long-term cycling data for different electrolyte systems, including systems containing LFOs.
FIG. 44A summarizes normalized discharge capacity data for different electrolyte systems including systems containing LFOs where cycling occurred at 20° C. during the first experiment.
FIG. 44B summarizes average-charge voltage data for different electrolyte systems including systems containing LFOs where cycling occurred at 20° C. during the first experiment.
FIG. 44C summarizes normalized discharge capacity data for different electrolyte systems, including systems containing LFOs where cycling occurs at 20° C. during a second experiment.
44D summarizes average-charge voltage data for different electrolyte systems, including systems containing LFOs where cycling occurred at 20 °C during a second experiment.
45A summarizes voltage data for different electrolyte systems, including systems containing LFOs, when the cell is maintained at 40 °C.
45B summarizes volume change data for different electrolyte systems, including systems containing LFOs, when the cell is maintained at 40 °C.
Figures 46a-d summarize the voltage-drop and impedance data generated during storage experiments.
46A summarizes the voltage-drop data for different electrolyte systems, including the system containing an LFO, after the cell was held at 60° C. for 500 hours at 4.4V.
46B summarizes impedance data for different electrolyte systems, including systems containing an LFO, before and after the cell was held at 60° C. for 500 hours at 4.4V.
46C summarizes voltage-drop data for different electrolyte systems, including one containing an LFO, after the cell was held at 60° C. for 500 hours at 2.5V.
46D summarizes impedance data for different electrolyte systems, including systems containing LFOs, before and after the cell was held at 60° C. for 500 hours at 2.5V.
47 shows example data for specific charging and discharging situations.
48a-f summarizes experimental heat flow data versus voltage. Figures 48a, c and e show the results for the first cycle to 4.4V. 48b, d and f show the results for the second cycle to 4.4V.
48A shows parasitic heat flow as a function of voltage for different electrolyte systems including systems containing DTD within the voltage range of 4.0 V to 4.4 V during the first cycle and of a cell containing 2% VC + 1% DTD. Differences between parasitic heat flows and experimental parasitic heat flow data are summarized.
FIG. 48B shows parasitic heat flow as a function of voltage for different electrolyte systems including systems containing DTD within the voltage range of 4.0 V to 4.4 V during the second cycle and for cells containing 2% VC + 1% DTD. Differences between parasitic heat flows and experimental parasitic heat flow data are summarized.
48C shows parasitic heat flow as a function of voltage for different electrolyte systems including systems containing LFOs within the voltage range of 4.0 V to 4.4 V during the first cycle and of cells containing 2% VC + 1% DTD. Differences between parasitic heat flows and experimental parasitic heat flow data are summarized.
Figure 48d shows parasitic heat flow as a function of voltage for different electrolyte systems, including systems containing LFOs, within the voltage range of 4.0 V to 4.4 V during the second cycle and of cells containing 2% VC + 1% DTD. Differences between parasitic heat flows and experimental parasitic heat flow data are summarized.
Figure 48e shows parasitic heat flow as a function of voltage for different electrolyte systems including systems containing an LFO within the voltage range of 4.0 V to 4.4 V during the first cycle and of a cell containing 2% VC + 1% DTD. Differences between parasitic heat flows and experimental parasitic heat flow data are summarized.
48F shows parasitic heat flow as a function of voltage for different electrolyte systems including systems containing an LFO within the voltage range of 4.0 V to 4.4 V during the second cycle and of a cell containing 2% VC + 1% DTD. Differences between parasitic heat flows and experimental parasitic heat flow data are summarized.
50a-c summarizes experimental mean-parasitic-heat-flow data as a function of cycle number for different electrolyte systems.
50A summarizes experimental mean-parasitic-heat-flow data as a function of cycle number for electrolyte systems containing 2% VC + 1% DTD and 2% FEC + 1% DTD.
50B shows 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% Summarizes the experimental mean-parasitic-heat-flow data as a function of cycle number for electrolyte systems containing FEC.
FIG. 50C shows experimental mean- Summarize parasitic-heat-flow data.
Figure 51 summarizes the experimental data from Figures 50a-c showing the best performing cell from parasitic-heat-flow experiments.
Figures 52a-d summarize experimental data of different electrolyte systems containing LFOs compared to controls without LFOs with cycling up to 4.2 V.
52A summarizes Coulombic efficiency versus cycle number data for an electrolyte system comprising a system containing an LFO with cycling up to 4.2 V.
52B summarizes the plotted charge endpoint capacity versus cycle number data for different electrolyte systems including systems containing an LFO with cycling to 4.2 V.
52C summarizes data of change in voltage versus number of cycles for different electrolyte systems, including systems containing an LFO with cycling up to 4.2 V.
52D summarizes the normalized discharge capacity versus cycle number data for different electrolyte systems including different systems containing LFOs with cycling up to 4.2 V.
Figures 53a-d summarize experimental data of different electrolyte systems containing LFOs compared to controls without LFOs with cycling up to 4.3 V.
53A summarizes Coulombic efficiency versus cycle number data for an electrolyte system comprising a system containing an LFO with cycling up to 4.3 V.
53B summarizes the plotted charge endpoint capacity versus cycle number data for different electrolyte systems, including systems containing an LFO with cycling to 4.3 V.
53C summarizes data of change in voltage versus number of cycles for different electrolyte systems, including systems containing an LFO with cycling up to 4.3 V.
53D summarizes the normalized discharge capacity versus cycle number data for different electrolyte systems including different systems containing LFOs with cycling up to 4.3 V.
Figures 54a-d summarize experimental data of different electrolyte systems containing LFOs compared to controls without LFOs with cycling up to 4.4 V.
54A summarizes Coulombic efficiency versus cycle number data for an electrolyte system comprising a system containing an LFO with cycling up to 4.4 V.
54B summarizes the plotted charge endpoint capacity versus cycle number data for different electrolyte systems, including systems containing an LFO with cycling to 4.4 V.
54C summarizes the change in voltage versus cycle number data for different electrolyte systems, including systems containing an LFO with cycling up to 4.4 V.
54D summarizes the normalized discharge capacity versus cycle number data for different electrolyte systems including different systems containing LFOs with cycling up to 4.4 V.
55A summarizes data of Coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
55B summarizes data of upper cut-off voltage versus partial fade for different electrolyte systems, including systems containing LFOs.
55C summarizes data of charge end point slippage versus upper cut-off voltage for different electrolyte systems including systems containing LFOs.
FIG. 56A shows an enlarged view of FIG. 55A and summarizes data of Coulombic inefficiency versus upper limit cut-off voltage for different electrolyte systems, including systems containing LFOs.
FIG. 56B shows an enlarged view of FIG. 55B and summarizes data of partial fade versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs.
FIG. 56C shows an enlarged view of FIG. 55C and summarizes the data of charge end point slippage versus upper cut-off voltage for different electrolyte systems including systems containing LFOs.
57 shows impedance data generated during and after ultra-precise cycling experiments.
58a-d summarize experimental data of an electrolyte system containing an LFO with an anode made from NMC622 with two different coatings.
58A summarizes experimental data of voltage drop after storage at 60° C. for 500 hours of various electrolyte systems at 4.4V.
58B summarizes experimental data of impedance before and after storage at 60° C. for 500 hours of various electrolyte systems at 4.4 V.
58C summarizes experimental data of voltage drop after storage at 60° C. for 500 hours of various electrolyte systems at 2.5V.
58D summarizes experimental data of impedance before and after storage at 60° C. for 500 hours of various electrolyte systems at 2.5 V.
60 is Guangzhou Tinci Materials Technology Co., Ltd. and Shenzhen Capchem Technology Co., Ltd. Summarize experimental data of mass change from air exposure over time for the product's LFO.
61 is Guangzhou Tinci Materials Technology Co., Ltd. and Shenzhen Capchem Technology Co., Ltd. Summarize experimental data from thermogravimetric analysis of the product's LFO.

1 shows the 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 connected to correspond to the drive motor 102A and/or 102B, battery cell 106 and electronic device 108 . In general, battery cells 106 supply electricity to power electronics of electric vehicle 100 and propel electric vehicle 100 using drive motors 102A and/or 102B. The electric vehicle 100 includes a number of other components not described herein but known to those skilled in the art. Although the structure of the electric vehicle 100 in FIG. 1 is shown as having four wheels, other electric vehicles may have four or fewer wheels. Further, other types of electric vehicles 100 may incorporate the inventive concepts described herein, including motorcycles, aircraft, trucks, boats, and train engines, among other types of vehicles. Certain components created using aspects of the present disclosure may be used in vehicle 100 .

2 shows a schematic diagram of an exemplary energy storage system 200 showing various components. The energy storage system 200 generally includes a modular housing having at least a base 202 and four side walls 204 (only two shown in the figure). The module housing is generally electrically isolated from the housing battery cell 206. This can occur through physical separation, through electrical insulation layers, through the selection of insulating materials as module housings, through any combination of these, or through other methods. Base 202 may be an electrically insulating layer on top of a metal sheet or nonconductive/electrical insulating material such as polypropylene, polyurethane, polyvinyl chlorine, other plastics, nonconductive composites or insulated carbon fibers. Additionally, sidewall 204 may include an insulating layer or may be formed of a non-conductive or electrically insulating material such as polypropylene, polyurethane, polyvinyl chlorine, other plastics, non-conductive composites, or insulated carbon fibers. One or more interconnection layers 230 may be disposed over the battery cell 206 having a top plate 210 disposed over the interconnection layer 230 . Top plate 210 may be a single plate or may be formed from multiple plates.

Each battery cell 106 and 206 is often a lithium-ion battery cell having an electrolyte containing lithium ions and a positive electrode and a negative electrode. 3 shows a schematic diagram of a lithium ion cell 300 . Lithium ions 350 are dispersed throughout electrolyte 320 in vessel 360 . Container 360 may be part of a battery cell. Lithium ions 350 move between the positive electrode 330 and the negative electrode 340 . The separator 370 separates the cathode and anode. Circuit 310 connects the cathode and anode.

New research by the inventors has identified a new electrolyte and battery system for use in grid and electric vehicle applications. These systems include: 1) vinylene carbonate (VC) mixed with l,3,2-dioxathiolane-2,2-dioxide (DTD, also known as ethylene sulfate) or other sulfur-containing additives, 2) DTD or other fluoroethylene carbonate (FEC) mixed with a sulfur-containing additive, and 3) prop-1-ene-1,3-sultone (PES) mixed with a DTD or other sulfur-containing additive; It is based on a mixed two-additive electrolyte system. This two-additive electrolyte system contains lithium nickel manganese cobalt with the composition LNi _x Mn _y Co _z 0 ₂ (abbreviated NMC commonly or NMCxyz, where x, y, and z are the molar ratios of nickel, manganese, and cobalt, respectively). It is paired with an anode made from an oxide. In certain embodiments, the anode is formed from NMC111, NMC532, NMC811, or NMC622. In certain embodiments, NMC532 anodes formed from single crystal, micrometer-sized particles resulting from micrometer-sized electrodes of a continuous crystal lattice (or grains) have materials and processing conditions that are better than those using conventional materials and processing conditions. It has been shown to be particularly robust in part because it produces large grain sizes.

Typical processing conditions produce NMC electrodes in which nano-sized particles are packed into larger micrometer-sized agglomerates, creating grain boundaries at the nanometer scale. Since grain boundaries are defects that tend to reduce desirable properties (eg, electrical properties), it is generally desirable to reduce the number of grains and increase the grain size. Processing can create larger domains on the micrometer size scale, thereby reducing the number of grain boundaries in the NMC electrode, increasing its electrical properties. This increase in properties creates a more robust battery system. In certain embodiments, other NMC electrodes can be processed to produce larger domain sizes (on the micrometer size scale or higher), for example NMC111, NMC811, NMC622 or other NMC compounds, resulting in more robust systems.

The anode may be coated with a material such as aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), or other coatings. Coating the anode is advantageous because it can help reduce interfacial phenomena at the anode, such as parasitic reactions, thermal abuse or other phenomena that can degrade the system. The cathode may be made of natural graphite, artificial graphite, or other materials.

The electrolyte may be organic or non-aqueous, including ethylene carbonate, ethyl methyl carbonate, methyl acetate, propylene carbonate, dimethyl carbonate, diethyl carbonate, other carbonate solvents (cyclic or acyclic), other organic solvents, and/or other non-aqueous solvents. It may be a lithium salt (eg, LiPF ₆ ) dissolved in a combination of aqueous solvents. The solvent is present in a greater concentration than the additive, generally greater than 6% by weight. Experimental data are generated using electrolyte solvents (with or without MA) including EC and EMC, but these solvents are merely examples of other carbonate solvents and other non-aqueous solvents in particular. EC and EMC solvents were used in experiments to control the system tested to understand the effect of addition of MA as an additive, electrode, and solvent. Thus, the electrolyte system may contain propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, other carbonate solvents (cyclic or acyclic), other carbonate solvents, including other organic solvents, and/or other non-aqueous solvents. and/or non-carbonated solvents may be used. The solvent is present in a greater concentration than the additive, generally greater than 6% by weight.

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

Certain of these novel battery systems can be used in energy-storage applications and automotive applications (including energy storage devices in electric vehicles) where charge/discharge rate and lifetime during rapid charge/discharge are critical. Specifically, MA can be used as an electrolyte solvent to provide longer life during charging and discharging at higher current rates.

Pre-experimental setup

Although the battery system itself may be packaged differently according to the present disclosure, the experimental set-up typically includes a two-additive electrolyte system and specific materials for use of the positive and negative electrodes, using a machine made of "pouch cells". The battery system was systematically evaluated using a typical setup of All percentages referred to within this disclosure are weight percentages unless otherwise stated. One skilled in the art will understand that the type of additives to be used and the concentrations to be applied will depend on the characteristics most desired to be improved and the design and other components used in the lithium ion battery to be manufactured.

pouch cell

The pouch cells used in the experimental set-up contain 1 M LiPF ₆ in the solvent to which additives are added. Depending on the concentration of methyl acetate (0, 20, or 40%), the electrolyte was (1) 1.2M LiPFe in 30% ethylene carbonate and 70% ethyl methyl carbonate, (2) 24% ethylene carbonate, 56% ethyl methyl carbonate, and 1.2M LiPF ₆ in 20% methyl acetate, or (3) 1 M LiPFe in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 1.2M LiPF ₆ in 40% methyl acetate. To the electrolyte, additive components are added in specific weight percentages.

Pouch cells used an anode made of NMC532 with micrometer-sized particles (sometimes referred to as single crystal NMC532) and a cathode made of artificial graphite, unless otherwise specified. To test a particular battery system, different anodes and cathodes (containing native graphite) are used, including the standard NMC532 (with particles smaller than NMC with micrometer-sized particles) and NMC622.

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

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

Electrochemical Impedance Spectroscopy

Electrochemical impedance spectroscopy (EIS) measurements were performed on pouch cells after storage and formation. After the cell was charged and discharged to 3.8 V, it was moved to a temperature box set at 10.0 ± 0.1 °C. AC impedance spectra were collected at 10 points per decade from 100 kHz to 10 mHz with a signal amplitude of 10 mV at 10.0±0.1 °C.

Effect of LFOs on Impedance: In certain embodiments, LFOs are included in two or three electrolyte additive systems to partially reduce the impedance of the system. 35a-d show that LiPO ₂ F ₂ (LFO, or lithium difluorophosphate) reduces cell impedance after formation in most cases. However, when the LFO is included in 2% PES + 1% DTD + 1% TTSPi (collectively, PES211), an increased impedance is observed. The anode is single crystal NMC 532 and the cathode is artificial graphite.

35a-d summarize the experimental results of the electrolyte system with an anode of NMC 111 and a cathode of artificial graphite. After formation, pouch cells were measured at 10 °C and 3.8 V. The control electrolyte in FIGS. 35a-d is 1.0 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 35A shows 1.0 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate (control electrolyte); 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; control electrolyte + 1% LiPO ₂ F ₂ ; Experimental impedance data are summarized plotting the negative of the imaginary part of the impedance against the real part of the impedance of control electrolyte + 2% LiPO ₂ F ₂ and 20% methyl acetate + 1% LiPO ₂ F ₂ . FIG. 35B shows a control electrolyte (same control as in FIG. 35A), 2% VC, 2% VC + 1% LiPO ₂ F ₂ ; 20% MA + 1% LiPO ₂ F ₂ + 2% VC; PES211; and experimental impedance data plotting the negative of the imaginary part of the impedance against the real part of the impedance of PES211 + 1% LiPO ₂ F ₂ . FIG. 35C is a control electrolyte (same control as in FIG. 35A), 2% FEC, 2% FEC + 1% LiPO ₂ F ₂ ; 1% DTD; and experimental impedance data plotting the negative of the imaginary part of the impedance against the real part of the impedance of 1% DTD + 1% LiP0 ₂ F ₂ . 35D shows a control electrolyte (same control as in FIG. 35A), 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1% LiP0 ₂ F ₂ ; 2% LiP0 ₂ F ₂ ; 20% MA + 1% LiP0 ₂ F ₂ ; 2% VC; 2% VC + 1% LiP0 ₂ F ₂ ; 20% MA + 1% LiPO ₂ F ₂ + 2% VC; PES211; PES211 + 1% LiP0 ₂ F ₂ ; 2% FEC, 2% FEC + 1% LiP0 ₂ F ₂ ; 1% DTD; and 1% DTD + 1% LiP0 ₂ F ₂ experimental impedance data are summarized.

As can be seen in Figures 35a-d, adding an LFO to most systems reduces impedance. However, in the presence of PES211, the addition of an LFO increases the impedance.

36 shows 2% VC in an electrolyte solution of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 1% LiP0 ₂ F ₂ + 2% VC; 1% LiP0 ₂ F ₂ + 2% FEC; and experimental EIS data of electrolyte systems containing additives of 1% LiP0 ₂ F ₂ + 1% VC + 1% FEC are summarized. EIS measurements are taken after formation at 3.8 V, and 10 °C. The anode is single crystal NMC532 and the cathode is artificial graphite.

The LFO did not reduce impedance in systems tested with NMC532 anodes and synthetic graphite cathodes. Impedance reduction failure may be due to larger cathode or anode surfaces. However, the LFO also did not increase the impedance. Thus, the addition of an LFO reduces or neutralizes the impedance.

Ultra-precise cycling and storage experiments

To study the efficacy of a battery system of the present disclosure comprising a working electrolyte additive and electrodes, ultra high precision cycling (UHPC) was performed. A standard UHPC procedure consists of cycling the cell from 2.8 to 4.3 V at 40 °C using a current corresponding to C/20 for 15 cycles to generate data.

UPHC is applied to measure coulombic efficiency in case of coulombic efficiency, charge endpoint capacity slippage and other parameters with an accuracy of 30 ppm. Details of the UHPC procedure are described in T. M. Bond, J. C. Burns, D. A. Stevens, H. M. Dahn, and J. R. Dahn, Journal of the Electrochemical Society, 160, A521 (2013), incorporated herein in its entirety.

Matrices measured and/or determined from UHPC measurements of particular interest include: Coulombic efficiency, normalized Coulombic inefficiency, normalized charge endpoint capacity slippage, normalized discharge capacity (or fade rate), and delta V. Coulombic efficiency is the discharge capacity (Qd) divided by the previous cycle's charge capacity (Qc). It tracks parasitic reactions that occur in Li-ion cells and includes contributions from both the anode and cathode. A higher CE value indicates less electrolyte decomposition of the cell. Coulombic efficiency per hour (CIE/h) is the normalized (per hour) Coulombic efficiency where the Coulombic efficiency is defined as 1-CE. This is calculated by taking 1-CE and dividing CE by the time of the measured cycle. The charge endpoint capacity movement (or slippage) tracks parasitic reactions and anode material mass loss, if any, that occur at the anode. Less movement is better and is associated with less electrolyte oxidation. Normalized discharge capacity, or fade rate, is another important indicator of a battery system with a low fade rate and generally longer life. Delta V is calculated as the difference between the average charge voltage and average discharge voltage. Since cycling is desired to occur, the delta V change is closely related to polarization growth with a lower delta V change. UHPC measurements are particularly suitable for comparing electrolyte compositions because they can track matrices with high accuracy and precision and evaluate various degradation mechanisms in a relatively rapid manner.

Two-Electrolyte Systems with FEC or VC as Additives: In certain embodiments, a two-additive electrolyte system, a concentration of each additive of about 0.25-6%, forms part of a battery system. The battery system may also include a positive electrode made of NMC111, NMC532, NMC811, NMC622, or another NMC composition (NMCxyz). In certain embodiments, positive electrodes made from NMC532 with micrometer-sized particles appear to be particularly robust in part because processing conditions generally result in larger crystal grain sizes than processing conditions produce.

Typical process conditions lead to NMC electrodes with nanometer-sized grains packed into larger micrometer-sized agglomerates, creating grain boundaries at the nanometer scale. Since grain boundaries are defects that tend to reduce desirable properties (eg, electrical properties), it is generally desirable to reduce the number of grains and increase the grain size. Current treatment creates larger domains on the micrometer-size scale, reducing grain boundaries and increasing electrical properties in NMC electrodes. The increase in properties creates a more robust battery system. In certain embodiments, other NMC electrodes can be processed to produce larger domain sizes (on the micrometer size scale or higher), eg, NMC11, NMC811, NMC622 or other NMC compounds, resulting in more robust systems.

The anode may be coated with a material such as aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ), or other coatings. 4a-j show a novel two-additive electrolyte system in a base electrolyte system containing 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, using an anode composed of single crystal NMC532 and a cathode composed of artificial graphite. Typical experimental data of a two-additive system of the present disclosure collected during UHPC experiments comparing (VC + DTD and FEC + DTD) and single-additive electrolyte systems are shown. 4a-j illustrate the advantages of the two-additive system of the present disclosure, specifically the addition of DTD to an electrolyte system containing VC or FEC.

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

Figures 4a-j show the benefits of electrolytes with two-additives, specifically VC + DTD and FEC + DTD. Experimental data show that, in a base electrolyte system containing 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, adding DTD to an electrolyte system containing VC or FEC results in an electrolyte system containing only VC or FEC as an additive. shows that the performance of Specifically, Figures 4a-j show that the two-additive systems containing (VC + DTD and FEC + DTD) have higher CE (lower electrolyte degradation in the cell) compared to systems without additives or with only one additive. and lower charge endpoint motion (lower electrolyte degradation at the anode). 4a-j also show a preferred lower fade rate (Qd). Thus, an electrolyte system with two additives (VC + DTD and/or FEC + DTD) is better than an electrolyte system containing only a single additive of DTD, VC, or FEC (in terms of CIE/h, CE, and end-of-charge slippage). ) has excellent performance.

Figure 5 summarizes the last three cycles of data generated during the experiments shown in Figures 4a-j. FIG. 5A is time-normalized coulombic inefficiency (CIE/h) per hour for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. Shows the last three cycles of 5B shows the last three cycles of partial slippage per hour for an electrolyte system containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. do. 5C shows the last three cycles of partial fade per time for an electrolyte system containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. .

5a-c show that electrolyte systems containing VC + DTD and FEC + DTD have lower time normalized Coulombic inefficiencies compared to systems containing only one additive - 2% FEC, 2% VC, or 1% DTD. (CIE/h), and lower partial slippage per hour (meaning these electrolyte systems have a longer lifetime). 5a and 5b show that 1% DTD without other additives shows the highest CIE/h and partial slippage. However, when DTD is mixed with VC or FEC, the two additives form a previously unexpected synergistic effect resulting in less CIE/h and partial slippage in a two-additive electrolyte system compared to a single additive. . 5C shows that the presence of 1% DTD reduces fractional fade per hour either as a single additive or as part of a two-additive electrolyte system with VC or FEC. This indicates that DTD is an important additive for increasing the life of the battery system of the present invention. In addition to DTD, other sulfur-containing compounds may function in a similar way and increase battery life.

Methyl Acetate as Electrolyte Solvent: In certain embodiments, methyl acetate is used as a solvent (at a concentration of 60% or less) to improve battery-system life when higher charge/discharge rates and other characteristics are expected. This is especially important in automotive and other applications. 9a-i are typical data collected during some of the ultra-high-precision experiments showing that methyl acetate can be added to electrolyte systems containing VC or FEC to increase electrolyte conductivity and lower viscosity without sacrificing much life. represents data. The increase in conductivity and decrease in viscosity are important in certain applications requiring faster fill rates.

9A shows 2% FEC in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and Coulombic efficiency (CE) versus cycle number for an electrolyte system comprising 2% FEC + 1% DTD in a base electrolyte of 1.2M 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. shows

9B shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and 2% FEC + 1% DTD in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. show

9C shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and discharge capacity versus cycle number for an electrolyte system comprising 2% FEC + 1% DTD in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate.

9D shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and 2% FEC + 1% DTD in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate versus the difference between average charge and average discharge voltages. Shows the number of cycles.

9F shows 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and Coulombic efficiency (CE) versus cycle number for an electrolyte system comprising 2% VC + 1% DTD in a base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. do.

9G shows 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and 2% VC + 1% DTD in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. show

9H shows 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and 2% VC + 1% DTD in a base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate.

9i shows 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate, and 20% methyl acetate; 2% VC in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate; and 2% VC + 1% DTD in a basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate. Difference between average discharge voltage and average charge voltage versus cycles. shows the number of

Figures 9a-i show that in systems containing both VC and FEC, the addition of MA as an electrolyte solvent does not significantly sacrifice the overall performance of the battery system, and the long-term cycling and plating experiments described below show lifetime under higher charge rates. shows this increase. 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. Figures 10a-c show the average of the last three cycles of data generated during the experiment shown in Figures 9a-i. 10A-C confirms that the addition of MA as an electrolyte solvent does not significantly sacrifice the overall performance of a battery system of the present disclosure comprising a two-additive electrolyte system.

LFO as Additive: Figures 39a-h and 40a-h summarize the results of UHPC experiments showing that LFO generally functions well within the electrolyte system, allowing the properties of the system to function well compared to the control electrolyte.

37a-f and 38a-f summarize experimental storage data for different electrolyte systems containing LFOs, compared to a control without LFOs.

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

46a-d show the results of storage experiments for cells with more complex electrolytes show the ability to match 2% FEC + 1% DTD in storage performance.

52a-d, 53a-d, 54a-d and 55a-c show the results of an additional electrolyte system containing LFO and 2% VC + 1% DTD for comparison purposes. As can be observed, certain electrolyte systems with LFOs perform as well or slightly better than the 2% VC + 1% DTD system. 56a-c show the results of additional experiments for CIE, partial fade, and partial slippage. 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 (though not quite as good as the 2% VC + 1% DTD system). These experimental data are consistent with the TAM experimental data.

57 shows the effect of UHPC cycling on impedance. LFO systems generally perform well. Figures 58a-d summarize experimental data for an electrolyte system comprising an LFO with an anode made of NMC 622 with two different coatings, labeled A and B. In the different electrolyte systems studied, the LFO has an effect on the voltage drop and the reduction of the impedance of the system.

LFO is Guangzhou Tinci Materials Technology Co., Ltd. and Shenzhen Capchem Technology Co., Ltd. 60 shows that, regardless of supplier, the reaction rates are similar in the presence of air for a time period of at least 50 minutes or less. Figure 61 shows similar mass loss through thermogravimetric analysis ("TGA") experiments performed in an argon environment with a temperature ramp of 5 °C/min.

long cycling

The lifetime of a battery system is an important characteristic of a battery system. Charge and discharge rates can affect lifetime. Long-term cycling experiments help determine how resilient a battery system is over time under expected operating conditions. It is important to select a battery system with sufficient life for the desired application.

Aspects of the present disclosure represent long-term cycling, which is desirable for different applications, including grid and automotive storage. Specifically, two-additive electrolyte systems of VC + DTD and FEC + DTD, in which MA in a concentration of up to 60% is used as solvent, are of particular relevance for automotive applications (especially energy storage in electric vehicles), where The charge and discharge rates of are usually higher than in grid-storage applications.

In long-term cycling experiments, single crystal NMC532 was mainly used as the anode (unless otherwise specified) and artificial graphite was used as the cathode (unless otherwise specified). Prior to the long-term cycling experiments, the pouch cells were subjected to a forming process. The cell was first charged to 4.2V at 11mA (C/20) and discharged to 3.8V. The cell was transferred to a glove box and moved, cut open to release the resulting gas, and then vacuum sealed again. After formation, the cells were cycled on a Neware charging system. The cell was placed in a temperature controlled box at 40 °C +/- 0.2 °C or 20 °C +/- 0.2 °C. The cell is charged at 3.0V and top of charge (4.2V or 4.3V) with a current of C/3 (half cycle of 3 hours) and a constant voltage step at the top of charge until the current falls below C/20. cycled between Every 50 cycles, the cell went through one complete cycle at C/20.

Two-Electrolyte Systems with FEC or VC as Additives: In certain embodiments, a two-additive electrolyte system in which the concentration of each additive is between about 0.25 and 6% forms part of a battery system. Figures 6a–f show data from a typical experiment studying long-term cycling at 40 °C and C/3 constant charge, constant voltage (CCCV) charge rate. 6a-f illustrate the advantages of a two-additive electrolyte system of the present disclosure, particularly an electrolyte comprising a DTD with VC or FEC. 6A shows experimental data of capacity versus cycle number for electrolyte systems comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, which Cycled between 3.0 V and 4.2 V. 6B shows experimental data of normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. , which is cycled between 3.0 V and 4.2 V. 6C shows voltage hysteresis (average charge voltage and Shows experimental data of average discharge voltage (difference between) versus number of cycles, cycled between 3.0 V and 4.2 V. 6D shows experimental data of capacity versus cycle number for electrolyte systems comprising 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, which Cycled between 3.0 V and 4.2 V. 6E shows experimental data of normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. , which is cycled between 3.0 V and 4.2 V. 6F shows experimental data of voltage hysteresis versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD; It cycles between 3.0 V and 4.2 V. Experimental data show that the two-additive electrolyte systems (DTD + FEC and DTD + VC) experience less polarization growth and less capacity when cycling to 4.2 or 4.3 V than single-additive electrolyte systems of VC or FEC. show what

Figures 7a-f show data from a typical experiment studying long-term cycling at 20 °C, C/3 CCCV charging rate. Similar to FIGS. 6a-f, FIGS. 7a-f illustrate the benefits of including DTD as an additive in an electrolyte system containing VC or FEC. Figures 7a-f confirm that the benefits seen at 40 °C are still present at lower temperatures, which is now the case at 20 °C. 7A shows experimental data of capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD; It cycles between 3.0 V and 4.3 V. 7B shows experimental data of normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. , which is cycled between 3.0 V and 4.3 V. 7C shows voltage hysteresis (between average charge voltage and average discharge voltage) for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. difference) versus number of cycles, cycled between 3.0 V and 4.3 V. 7D shows experimental data of capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD, which Cycled between 3.0 V and 4.3 V. 7E shows experimental data of normalized capacity versus cycle number for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. , which is cycled between 3.0 V and 4.3 V. 7F shows voltage hysteresis (difference between average charge voltage and average discharge voltage) for electrolyte systems containing 1% DTD, 2% FEC, 2% FEC + 1% DTD, 2% VC, and 2% VC + 1% DTD. ) versus cycle number, which is cycled between 3.0 V and 4.3 V. Figures 7a-f confirm the advantage of incorporating DTD in the electrolyte along with VC or FEC, especially when cycling occurs below 4.3V.

6a-f illustrate the advantages of a two-additive electrolyte system consisting of DTD+VC or DTD+FEC. 6a-f show that including DTD with VC or FEC as part of a two-additive electrolyte system and cycling at 40 °C leads to less capacitance loss and lower polarization growth at 4.2 and 4.3V. Similarly, Figures 7a-f show the benefits of DTD when cycling at 20 °C for long periods of time. 7a-f show that incorporating a DTD with VC or FEC as part of a two-additive electrolyte system and cycling at 20 °C leads to less capacity loss at 4.2V (slightly) and 4.3V (larger) and polarization shows a slowdown in growth. Thus, a two-addition system comprising DTD with VC or FEC at 20° C. or 40° C. improves the battery system by reducing capacity loss and lowering polarization growth.

In certain embodiments, the anode is formed of NMC111, NMC532, NMC822, NMC622, and/or NMCxyz. In particular, positive electrodes made of single crystal NMC532 were found to be particularly robust, in part because the grain size of NMC532 is larger than that of other standard, more polycrystalline NMC materials with smaller grain sizes. 8A-I depict typical empirical data collected during cycling experiments for electrolyte compositions according to certain aspects of the present disclosure comprising a positive electrode formed of single crystal NMC532. 8A shows peak capacity vs. Experimental data of the number of cycles is shown, with cycling between 3.0 V and 4.3 V at 40° C. in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8B shows normalized capacities for electrolyte systems comprising 2% FEC, 1% FEC + 1% DTD, 2% FEC + 1% DTD, 1% FEC + 1% MMDS, and 2% FEC + 1% MMDS. Experimental data versus number of cycles are shown, cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8C shows the voltage hysteresis ( Shows experimental data of difference between average charge voltage and average discharge voltage) versus number of cycles between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. cycled FIG. 8D shows peak capacity vs. Experimental data of the number of cycles is shown, with cycling between 3.0 V and 4.3 V at 40° C. in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8E shows normalized capacities for electrolyte systems comprising 2% VC, 1% VC + 1% DTD, 2% VC + 1% DTD, 1% VC + 1% MMDS, and 2% VC + 1% MMDS. Experimental data versus number of cycles are shown, cycling between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8F shows the voltage hysteresis ( Shows experimental data of difference between average charge voltage and average discharge voltage) versus number of cycles between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. cycled Figure 8G shows the peak capacity vs. Experimental data of number of cycles are shown, where cycled between 3.0 V and 4.3 V at 40° C. in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8H shows normalized capacities for electrolyte systems comprising 2% PES, 1% PES + 1% DTD, 2% PES + 1% DTD, 1% PES + 1% MMDS, and 2% PES + 1% MMDS. Experimental data versus number of cycles are shown, cycling between 3.0 V and 4.3 V at 40° C. in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8i shows the voltage hysteresis ( difference between average charge voltage and average discharge voltage), cycled between 3.0 V and 4.3 V at 40 °C in a basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. 8a-i show that NMC532 works well in a two-additive electrolyte system of 1% VC, 2% VC, 1% FEC or 2 FEC and 1% DTD. 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, generally in combination with ethylene carbonate and/or ethyl methyl carbonate, at a concentration of 60% or less by weight. 15a-f and 16a-f show the results of experiments performed at 20 °C and 40 °C, respectively. In cells containing MA as the solvent, cells with DTD performed better than cells without DTD.

15A shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.2 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate, capacity versus cycle number, taken at 20 °C. This is a plot of experimental data.

15B shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.2 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate, normalized capacity versus cycle number at 20 °C. is a plot of the experimental data taken from

15C shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.2 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and voltage _hysteresis (average charge voltage and average discharge voltage is a plot of experimental data taken at 20 °C, of the difference between (difference between) versus number of cycles.

15D shows 2% FEC in basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.3 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in a base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate. Experiments taken at 20 °C of capacity versus cycle number. It is a plot of the data.

15E shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.3 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate, normalized capacity versus cycle number at 20 °C. is a plot of the experimental data taken from

15F shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.3 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and voltage _hysteresis (average charge voltage and average discharge voltage is a plot of experimental data taken at 20 °C, of the difference between (difference between) versus number of cycles.

Figures 15a–f illustrate the importance of DTD in systems containing FEC and systems using MA as solvent at 20 °C. Cells with DTD performed better than cells without DTD in 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.

16a-f show the results of experiments performed at 40 °C. Cells with DTD performed better than cells without DTD in cells containing MA. 16A shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.2 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in a base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate. Experiments taken at 40 °C of capacity versus cycle number. It is a plot of the data.

16B shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.2 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate, normalized capacity versus cycle number at 40 °C. is a plot of the experimental data taken from

16C shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.2 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and voltage _hysteresis (average charge voltage and average discharge voltage is a plot of experimental data taken at 40 °C, of the difference between (difference between) versus number of cycles.

16D shows 2% FEC in basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.3 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate, capacity versus cycle number, taken at 40 °C. This is a plot of experimental data.

16e shows 2% FEC in basic electrolyte of 1.2 M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.3 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and 2% FEC + 1% DTD in base electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate, normalized capacity versus cycle number at 40 °C. is a plot of the experimental data taken from

16F shows 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, with cycling below 4.3 V; 1% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC + 1% DTD in basic electrolyte of 1.2M LiPF ₆ in 24% ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; 2% FEC in basic electrolyte of 1.2M LiPF ₆ in 18% ethylene carbonate, 42% ethyl methyl carbonate and 40% methyl acetate; and voltage _hysteresis (average charge voltage and average discharge voltage is a plot of experimental data taken at 40 °C, of the difference between (difference between) versus number of cycles.

Figures 16a–f illustrate the importance of DTD in systems containing FEC and systems using MA as solvent at 40 °C. In general, cells with DTD performed better than cells without DTD, especially cells without DTD in cells with MA. In a two-additive electrolyte system with 2% FEC + 1% DTD with 20% MA solvent, the effect of DTD is slightly mitigated compared to the same two-additive electrolyte system but without MA as solvent. Also, the addition of less than 40% MA at 4.3 V shortens the cycle life. That is, DTD and MA may have a symbiotic increase in the performance of the two-additive electrolyte system, but this increase is mitigated when operating on cycles below 4.3 V. Thus, in certain aspects of the present disclosure, only the electrolyte system operates below 4.2V. In another aspect of the present disclosure, the electrolyte system operates below 4.3 V but the MA concentration is less than 40%.

NMC622 as Anode: In certain embodiments, a battery system has a cathode made of NMC622. In certain embodiments, the anode is coated with a material such as aluminum oxide (Al ₂ O ₃ ), titanium dioxide (TiO ₂ ) or another coating. 17a-f show experimental data for long-term cycling of one- and two-additive electrolyte systems with positively coated NMC622 at 40 °C, C/3 CCCV. Dashed lines are extrapolated 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, with cycling below 4.3 V. 17B is a plot of experimental data of normalized capacity versus cycle number for an electrolyte system containing FEC and/or DTD, with cycling below 4.3 V. 17C 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 including FEC and/or DTD, cycling up to 4.3 V. 17D is a plot of capacity versus cycle number experimental data for electrolyte systems containing VC and/or DTD, with cycling below 4.3 V. 17E is a plot of experimental data of normalized capacity versus cycle number for an electrolyte system containing VC and/or DTD, with cycling below 4.3 V. 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 including VC and/or DTD, cycling up to 4.3 V.

17a-f show that experimental data show that electrolyte systems with two additives - VC + DTD and FEC + DTD - perform better than any single additive of VC, FEC or DTD, even when different anodes are selected. do.

Natural Graphite as Negative Cathode: In certain embodiments, the battery system has a negative electrode made of natural graphite. 18a-b and 19 show data from additional long-term cycling experiments performed using single crystal NMC532 as the anode and natural graphite as the cathode at 40°C, C/3 CCCV. 18A shows the plotted capacity versus cycle number. 18B shows the plotted normalized capacity versus cycle number. 19 shows voltage hysteresis (difference between average charge voltage and average discharge voltage) versus cycle number. 18a-b and 19 show that the two-electrolyte additive system with DTD + FEC improves performance compared to the electrolyte system with only FEC as an additive, but a comparison with FIG. 6-f where an artificial-graphite cathode is used. , demonstrating that the performance of this particular artificial graphite negative electrode outperforms 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 cathode is important as a cost saving measure over synthetic graphite, which is generally more expensive. Thus, if cost is a major driver and some performance trade-off can be made, natural graphite may be a good choice.

LFO as Additive: In certain embodiments, LFO is added to the electrolyte system. 41A summarizes data of Coulombic inefficiency versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs. 41B summarizes data of fractional fade versus upper limit cut-off voltage for different electrolyte systems, including systems containing an LFO. 41C summarizes data of charge endpoint capacity slippage versus upper cut-off voltage for different electrolyte systems, including systems containing an LFO. FIG. 42A shows an enlarged view of FIG. 41A and summarizes data of Coulombic inefficiency versus top cut-off voltage for different electrolyte systems, including systems containing LFOs. FIG. 42B shows an enlarged view of FIG. 41B and summarizes data of partial fade versus top cut-off voltage for different electrolyte systems, including systems containing LFOs. FIG. 42C shows an enlarged view of FIG. 41C and summarizes data of charge endpoint capacity slippage versus upper cut-off voltage for different electrolyte systems, including systems containing LFOs. The addition of an LFO to control the electrolyte greatly improves the UHPC results. In the presence of MA, 1% LFO dramatically improves the situation compared to 0.5% LFO. CIE/h is about 4xl0 ^-5 h ^-1 for 1% LFO in the control. In 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-d summarize long-term cycling data for different electrolyte systems, including systems containing LFOs. Long-term cycling results showed that the addition of an LFO dramatically improved impedance growth in the systems tested, confirming the UHPC data. In particular, 1% LFO added to an electrolyte system containing control electrolyte and 20% MA improves long-term cycling and impedance.

microcalorimetry

Microcalorimetry measures the heat flow into a cell during operation. The heat flow into the cell is a combination of three different effects: (1) ohmic heating, (2) entropy change due to Li intercalation in the electrode, and (3) parasitic reactions (electrolyte including additives, one disassembly of the electrode). Since the test cells contain the same physical design and differ only in the electrolyte, the difference in heat flow is primarily due to the difference in parasitic heat flow. Nevertheless, parasitic heat flow is developed by Downie et al. (Journal of the Electrochemical Society, 161, A1782-A1787 (2014)) and Glazier et al. (Journal of the Electrochemical Society, 164 (4) A567-A573 (2017)). can be extracted from the total heat flow using the Both of these references are incorporated herein in their entirety. Cells with lower parasitic heat flow during cycling have better lifetimes. The voltage dependence of the parasitic reaction rate can be observed by plotting the measured parasitic heat flow as a function of cell voltage.

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 nW) at 40 °C. Baseline shifts during the experiment did not exceed +/- 0.5 μW. All specifications and information regarding microcalorimetry calibration, cell connection and operating procedures can be found in the previous literature. (eg, Downie et al., ECS Electrochemical Letters 2, A106-A109 (2013).) The cell was cycled 4 times at C/20 rate between 3.0 V and 4.2 V to ensure a well-formed, stable SEI, It was then charged between different upper cut-off limits at 4.0 V and 1 mA to investigate parasitic heat flow and performance within different voltage ranges. Each pair of cells exhibits nearly identical performance, so only one set of heat flow data is provided for each electrolyte.

The 1 mA cycling protocol is as follows:

1. Charge to 4.2 V, discharge to 4.0 V

2. Charge to 4.3 V, discharge to 4.0 V (repeat)

3. Charge to 4.4 V, discharge to 4.0 V (repeat)

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.

In the experimental data in FIGS. 11 to 14 , a pouch cell with an anode made of single crystal NMC532 and an artificial graphite cathode was used. Excluding additives, the electrolyte was one of the following: (1) 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate, (2) 24, depending on the concentration of methyl acetate (0, 20 or 40%). 1.2M LiPF6 in % ethylene carbonate, 56% ethyl methyl carbonate and 20% methyl acetate; or (3) 1.2M LiPF ₆ in 18% ethyl carbonate, 42% ethyl methyl carbonate, and 40% methyl acetate.

11 shows the experimental data of a calorimetry experiment (parasitic heat flow versus voltage) when charging to 4.2 V. 12a and b show experimental data from a calorimetric experiment (parasitic heat flow versus voltage) when charging to 4.3 V. Since the charging to 4.3 V was repeated, each plot shows the result of one charging. 13a and b show experimental data (parasitic heat flow versus voltage) when charging to 4.4 V. Since the charging to 4.4 V was repeated, each plot shows the result of one charging. The difference in the plots (lower plots in Figures 11, 12a, 12b, 13a and 13b) is calculated by taking the heat flow for each electrolyte mixture and subtracting the heat flow produced by the control (2% FEC). Figure 14 shows a summary of the experimental data delivered in Figures 11-13. Table 1 summarizes the data presented in FIG. 14 in tabular form.

Table 1: Average parasitic heat flow per cycle (μW) (40 °C, 4.0 V vs. UCV, 1 mA)

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

LFO as additive: FIG. 47 shows how charge heat flow is related to parasitic heat flow, charge overvoltage and discharge overvoltage. 48A-F show the results of TAM experiments. The difference plot compares the system to 2% VC + 1% DTD. 48A-F show that 2% VC + 1DTD is superior to 2% FEC + 1DTD. They also show that when optimizing LFOs within a system, 1% LFO + 1% VC + 1% FEC is superior to 2% VC + 1% DTD above 4.3V. Comparing the system with 1% LFO, 1% LFO + 1% VC functions as much as 1% LFO + 1% VC + 1% FEC and is superior to 2% VC + 1% DTD above 4.3 V. As observed in Figures 50a-c, the optimal LFO composition is about 1.0%. 51 shows the average parasitic heat flow as a function of cycles, for the highest performing cell. 1% VC + 1% FEC and 0.5% LFO is the best performing system after 4.4 V cycles. 2% VC + 1% LFO is very similar to 2% VC + 1% DTD. Thus, systems with VC, with or without DTD are possible.

plating experiment

Plating experiments test the ability to charge at high rates. While fast charging is very important for energy storage when part of a vehicle, slower charging rates may be acceptable for grid-storage applications. Fast charging is primarily limited by lithium plating on the negative electrode, which leads to safety issues and shortens cycle and calendar life. Electrolyte systems that allow higher charge rates without plating are therefore advantageous. To study the plating of the cathode, a plating experiment was conducted. A greater capacity loss indicates greater lithium plating.

A plating experiment was performed to test the charging ability of the cell. After EIS measurement, the cells were charged and discharged at constant current (C-rate) of 1C, 1.5C and 2.0 C between 2.8 and 4.1 V using a Maccor charger system at 20.0 ± 0.1 °C. Pair cells were tested for all charging rates to ensure reproducibility. To measure the active lithium loss during cycling, the cell was cycled at C/20 once before and after the high charge rate segment. The upper cutoff voltage was set at 4.1 V to minimize electrolyte oxidation at the anode and to ensure that the cell does not have a fully loaded cathode, which would occur at 4.4 V in this cell. All pouch cells were cycled with external clamps to eliminate the effect of small amounts of gas that may be produced during cycling. The cell was stopped after about 350 hours of cycling or after the capacity loss reached 20%.

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

23 shows the experimental data from the plating test, where after every 30 cycles, the charging current was increased. A large capacity loss rate indicates lithium plating. At a charging current of 2C, all cells started to plate lithium. However, cells with DTD lose little capacity during plating. This indicates that the amount of plating in cells with DTD is less than in cells without. Besides DTD, other sulfur-containing compounds can act in a similar way to reduce plating.

24 shows the results of experimental data of peak capacity as a function of cycle number for different electrolyte systems. DTD was superior to MMDS in maintaining peak capacity for the two-additive electrolyte system when either DTD or MMDS were combined with VC.

Methyl Acetate as Electrolyte Solvent: Methyl acetate at concentrations up to 60% by weight is used as a solvent to reduce plating according to certain embodiments. 27-34 show the effect of using MA as a solvent in the presence of different electrolyte systems. 27 shows the results of a plating experiment to determine the effect of the presence of DTD as an additive and MA as a solvent 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 for 0% MA is 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. The remaining electrolyte for 20% MA is 1.2M LiPF ₆ in 24% ethylene carbonate and 56% ethyl methyl carbonate. The remaining electrolyte for 40% MA is 1.2M LiPF ₆ in 18% ethylene carbonate and 42% ethyl methyl carbonate. Figure 28 is an enlarged view of the specific data shown in Figure 27, which has a small low rate capacity loss.

27 and 28, greater capacity loss indicates greater lithium plating. 27 and 28 show that the presence of MA reduces the low rate capacity loss even at a charge rate of 2C. Thus, electrolyte systems containing 20% or 40% MA are good candidates for use in fast charging applications such as energy storage in vehicles that may be subject to high charging current rates.

29, 30 and 31 show the results of experimental data of electrolyte systems containing FEC as an additive. As indicated by the legend in the figures, other data sets include DTDs and/or MAs. 29, 30 and 31 show that the addition of MA to one- and two-additive electrolyte systems with FEC enables higher charge rates, which allow charging down to 2C without significant plating. point

Similarly, Figures 32, 33 and 34 show the results of experimental data of an electrolyte system containing VC as an additive. As indicated by the legend in the figures, other data sets include DTDs and/or MAs. Figures 32, 33 and 34 show that the addition of MA to one- and two-additive electrolyte systems with VC enables higher charge rates, indicating charge down to 2C without significant plating. .

LFO as Electrolyte Additive: Figures 44a-d summarize long-term cycling data under fast charge for different electrolyte systems, including systems containing LFO. As can be seen from the experimental data, the presence of MA reduces the amount of plating. Also, the LFO reduces the possibility of Li-plating during fast charging. For example, in FIG. 44A, the electrolyte system with 20% MA + 1% LFO showed significantly less loss of normalized discharge capacity than the other systems with either MA or LFO. Loss of normalized discharge capacity indicates plating.

gas volume measurement

The forming process is performed before the cells are used in their intended application, such as grid storage or energy storage in vehicles such as electric vehicles. During formation, cells undergo precisely controlled charge and discharge cycles, which are intended to activate the electrodes and electrolyte for use in their intended application. During formation, gas is evolved. If a sufficient amount of gas is produced (depending on the specific tolerances allowed by the cell and cell packaging), the gas may need to be released after the forming process and before application. This usually requires an additional step of breaking and resealing the seal. Although these steps are common in many battery systems, it is desirable to eliminate them, if possible, by choosing systems that produce less gas.

Gas volume experiments were conducted as follows: Ex-situ (static) gas measurements were used to measure gas evolution during formation and during cycling. Measurements were made using Archimedes' principle with a cell suspended from a scale in a state submerged in 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. The change in mass Am of a suspended cell in the density p of the fluid is related to the change in cell volume Δv, Δv = Am/p.

Two-Electrolyte Systems with FEC or VC as Additives: In certain embodiments, a two-additive electrolyte system in which the concentration of each additive is between about 0.25 and 6% forms part of a battery system. 20 shows the results of a gas-generation experiment, wherein the amount of gas released was measured according to the procedure described above. 20 shows that systems without DTD typically performed better, for example a system containing only 2% FEC as an additive performed better than 1% FEC + 1% DTD and 2% FEC + 1% DTD. . That is, DTD leads to higher gas volume formation during formation, and due to its desirable properties when DTD is combined with other additives, such as VC and FEC, if DTD is used as an additive, the system will be able to produce Includes mechanisms for safely handling gases, e.g., outgassing after formation as discussed above. 20 shows that a two-additive electrolyte system comprising MMDS and PES or FEC does not produce much additional gas (if any) when 2% PES or FEC is the only additive.

Methyl Acetate as Electrolytic Solvent: Methyl acetate at a concentration of 60% by weight or less is used as a solvent to reduce plating according to certain embodiments. 25 shows the results of a gas-generation experiment to determine the effect of MA as a solvent and the presence of DTD as an additive on the formed forming gas. The electrolyte systems tested included 2% additives (VC, FEC and PES) in electrolytes with 0%, 20% and 40% MA. The remaining electrolyte for 0% MA is 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. The remaining electrolyte for 20% MA is 1.2M LiPF ₆ in 24% ethylene carbonate and 56% ethyl methyl carbonate. The remaining electrolyte for 40% MA is 1.2M LiPF ₆ in 18% ethylene carbonate and 42% ethyl methyl carbonate.

25 shows that in two-additive electrolyte systems containing either VC or FEC with DTD, the increase in the amount of gas with the addition of MA changes less as the amount of MA increases. That is, there is a lower critical amount of gas generated when the DTD is part of a two-additive electrolyte system compared to a one-additive electrolyte system with only VC or FEC.

In-situ gas volume measurement

45A and 45B summarize the results of in situ gas experiments at 40 °C. A cell with an LFO, but no MA, shows less gassing during the hold segments of this test.

cell impedance

The two-additive electrolyte system and novel battery system disclosed herein have low cell impedance. Minimizing the cell impedance is desirable so that the cell impedance reduces the energy efficiency of the cell. Conversely, lower impedance leads to higher charge factor and higher energy efficiency.

Cell impedance was measured using electrochemical impedance spectroscopy (EIS). The pouch cell used a single-crystal NMC532 anode and an artificial cathode, unless otherwise noted, and EIS measurements were performed after formation. The cell was charged or discharged to 3.80 V before moving the cell to the 10.0 +/- 0.1 °C temperature box. AC impedance spectra were collected ten points per decade from 100 kHz to 10 mHz with a signal amplitude of 10 mV at 10.0 +/- 0.1 °C. From the measured AC impedance, the charge transfer resistance (R _ct ) was calculated and plotted.

Two-Electrolyte Systems with FEC or VC as Additives: In certain embodiments, a two-additive electrolyte system in which the concentration of each additive is between about 0.25 and 6% forms part of a battery system. 21 shows experimental data of cell charge transfer impedance experiments for a two-additive electrolyte system consisting of 1% or 2% of PES, FEC or VC and 1% DTD. 21 shows that these two-additive electrolyte systems with 1% or 2% of PES, FEC or VC and 1% DTD do not significantly increase the cell charge transfer impedance. In particular, systems with 1% VC and 1% DTD, 2% VC and 1% DTD, 1% FEC and 1% DTD, and 2% FEC and 1% DTD are the cells observed for single-additive systems without DTD. Indicates a cell impedance value similar to the charge transfer impedance. Therefore, this novel two-additive electrolyte system does not sacrifice significant charge transfer impedance performance by including a DTD.

Methyl Acetate as Electrolyte Solvent: Methyl acetate at a concentration of 60% by weight or less is used as a solvent for reducing plating according to certain embodiments. 26 shows the results of cell-charge transfer impedance experiments for electrolyte systems consisting of one- and two-addition systems with MA as one of the solvents. The additive-electrolyte systems tested were 2% additives VC, FEC and 2% with 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. PES was included. The electrolyte for 0% MA is 1.2M LiPF ₆ in 30% ethylene carbonate and 70% ethyl methyl carbonate. The remaining electrolyte for 20% MA is 1.2M LiPF ₆ in 24% ethylene carbonate and 56% ethyl methyl carbonate. The remaining electrolyte for 40% MA is 1.2M LiPF ₆ in 18% ethylene carbonate and 42% ethyl methyl carbonate. 26 shows that DTD only slightly increases the charge transfer impedance. Also, in two-additive electrolyte systems containing DTD and either VC or FEC, the addition of MA reduces the cell charge transfer impedance. In 40% MA solvent, the VC + DTD and FEC + DTD systems showed reduced charge transfer impedance from the corresponding systems without DTD and without MA as the solvent. In the PES + DTD two-additive electrolyte system, MA also reduced the charge transfer impedance of the system.

The foregoing disclosure is not intended to limit the disclosure to the precise form disclosed or to the specific field. As such, various alternative aspects and/or variations of this disclosure, whether explicitly described or implied herein, are contemplated as being possible in light of this disclosure. Having thus described aspects of the present disclosure, those 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, this disclosure is limited only by the claims. References to additives herein generally relate to operative additives unless otherwise stated herein.

In the foregoing specification, the present disclosure has been described with reference to specific aspects. However, as those skilled in the art will appreciate, the various aspects disclosed herein may be modified or otherwise implemented in various other ways without departing from the spirit and scope of the present disclosure. Accordingly, these descriptions are to be regarded as illustrative and intended to teach those skilled in the art how to make and use the various aspects of the disclosed battery system. It is to be understood that the forms of the disclosure shown and described herein are to be taken as representative aspects. Equivalent components or materials may be substituted for those representatively illustrated and described herein. Moreover, as will be clear to all those skilled in the art after having benefited from this description of the present disclosure, certain features of the present disclosure may be utilized independently of the use of other features. "including", "comprising", "incorporating", "consisting of", "have", " Expressions such as "is" are intended to be interpreted in a non-exclusive manner, ie as to permit the described item, composition or element to also be presented. References to the singular should also be construed as relating 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 is to be construed as meaning plus or minus 10%.

Further, the various aspects disclosed herein are to be taken in an illustrative and explanatory sense, and in no way should be construed as limiting the disclosure. All references to joinders (eg, attach, fasten, join, connect, etc.) are only used to aid the reader in understanding the present disclosure and to limit limitations, particularly the location of systems and/or methods disclosed herein. However, it may not make restrictions on direction or use. Therefore, references to binding expressions, if any, are to be interpreted broadly. Moreover, references to such combined expressions do not necessarily imply that the two components are directly connected to each other.

Additionally, any number term, e.g., "first", "second", "third", "primary", "secondary", "major" or any other general term and/or number term , in order to aid the reader's understanding of the various elements, aspects, changes and/or variations of the present disclosure, should be taken only as identifiers, with any limitations in particular, any elements, aspects, changes and/or It may not make a limitation to the order or preference of or to other components, aspects, changes and/or variations of the variants.

It will be appreciated that one or more of the components shown in the drawings/drawings may also be implemented in a more separate or integrated manner, such as may be useful depending on a particular application, or may be eliminated or deemed inoperable in certain instances.

Claims (16)

As a lithium-ion battery, the battery comprises:
cathode;
anode; and
A non-aqueous electrolyte comprising a lithium salt, a non-aqueous solvent, and an additive mixture;
At this time, the additive mixture,
1,3,2-dioxathiolane-2,2-dioxide, methylene methane disulfonate, trimethylene sulfate, 3-hydroxypropanesulfonic acid γ- a first operational additive comprising a sulfur-containing additive selected from the group consisting of sultones and glycol sulfites; and
a second working additive comprising vinylene carbonate; wherein a concentration of each of the first and second working additives is in the range of 0.25 to 6% by weight.
According to claim 1,
The sulfur-containing additive is 1,3,2-dioxathiolane-2,2-dioxide (1,3,2-dioxathiolane-2,2-dioxide), a lithium-ion battery.
According to claim 1,
The lithium-ion battery of claim 1, wherein the working additive does not include further additives.
According to claim 1,
The non-aqueous solvent is a lithium-ion battery comprising a carbonate solvent.
According to claim 1,
Wherein the non-aqueous solvent comprises methyl acetate, a lithium-ion battery.
According to claim 1,
wherein the working additive comprises less than 0.25% by weight of tris(-trimethly-silyl)-phosphate.
According to claim 1,
wherein the working additive comprises less than 0.25% by weight of tris(-trimethly-silyl)-phosphite.
According to claim 1,
The lithium-ion battery of claim 1 , wherein the lithium-ion battery excludes working additives of at least 0.25% by weight of tris(-trimethyl-silyl)-phosphate and tris(-trimethyl-silyl)-phosphite.
According to claim 1,
Wherein the positive electrode includes at least one lithium nickel manganese cobalt oxide (NMC) selected from the group consisting of NMC111, NMC532, NMC811 and NMC622, a lithium-ion battery.
According to claim 9,
The NMC has a grain size of greater than 0.5 micrometers, a lithium-ion battery.
According to claim 10,
The cathode is coated with aluminum oxide or titanium dioxide, lithium-ion battery.
According to claim 1,
The battery further comprises methyl acetate as a second non-aqueous solvent.
According to claim 1,
Wherein the lithium-ion battery retains 95% of its initial capacity after 200 cycles between 3.0 V and 4.3 V at 40 °C and a charge rate of C/3 CCCV.
An electric vehicle having a rechargeable battery, the vehicle comprising:
drive motor;
gear box;
electronic devices; and
An electric vehicle comprising the lithium-ion battery according to claim 1 .
As a nonaqueous electrolyte for lithium ion batteries,
The electrolyte is
lithium salt;
non-aqueous solvent; and
1,3,2-dioxathiolane-2,2-dioxide, methylene methane disulfonate, trimethylene sulfate, 3-hydroxypropanesulfonic acid γ- An additive mixture comprising a first operative additive comprising a sulfur-containing additive selected from the group consisting of sultone and glycol sulfite, and a second operative additive of vinylene carbonate ); including,
Wherein the concentration of each of the first working additive and the second working additive is 0.25 to 6% by weight, the non-aqueous electrolyte.
According to claim 15,
The non-aqueous electrolyte, wherein the sulfur-containing additive comprises 1,3,2-dioxathiolane-2,2-dioxide.

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