Electrolyte composition, and battery pack and device comprising same

Abstract

The invention relates to an electrolyte composition and a battery pack and a device comprising the electrolyte composition. An electrolyte composition for a battery pack is provided. An electrolyte composition includes a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from the group consisting of mono (trimethylsilyl) phosphites, bis (trimethylsilyl) phosphites, Li salt derivatives thereof, or combinations thereof. Further, a battery and a device comprising the electrolyte composition are provided.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electrolyte composition for a battery, a battery, and a device. BACKGROUND

[0002] The present disclosure relates generally to an electrolyte composition for a battery.

[0003] A battery cell can include an anode, a cathode, an electrolyte composition, and a separator. The battery cell can operate in a charging mode, receiving electrical energy. The battery cell can operate in a discharging mode, providing electrical energy. The battery cell can operate through charging and discharging cycles, where the battery first receives and stores electrical energy, and then provides electrical energy to a connected system. In a vehicle powered by electrical energy, the battery cell of the vehicle can be charged, and then the vehicle can travel for a period of time, powered by the stored electrical energy.

[0004] The battery cell includes an electrolyte composition that provides a lithium ion conduction path between the anode and the cathode. The electrolyte is an ionic conductor. The electrolyte is also an electronic insulator.

[0005] One of the factors that determines the commercial viability of a battery cell is its capacity and cycle tolerance. One or more battery cells of a motorized vehicle with an electric powertrain can be responsible for providing at least 30,000 hours of service. Such a high requirement can pose a challenge to one or more battery cells of the vehicle. SUMMARY

[0006] An electrolyte composition for a battery according to one or more embodiments is provided. The electrolyte composition includes a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, a Li salt derivative thereof, or a combination thereof.

[0007] In some embodiments, the Li salt derivative thereof is lithium bis(trimethylsilyl) phosphate.

[0008] In some embodiments, the partially substituted phosphite additive is bis(trimethylsilyl) phosphite.

[0009] In some embodiments, the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 weight percent based on the total weight of the electrolyte composition.

[0010] In some embodiments, the partially substituted phosphite additive is present in an amount of about 1 to about 5 weight percent based on the total weight of the electrolyte composition.

[0011] In some embodiments, the partially substituted phosphite additive is present in an amount of about 2 to about 4 weight percent based on the total weight of the electrolyte composition.

[0012] In some embodiments, the electrolyte composition further includes a co-additive.

[0013] In some embodiments, the co-additive includes one or more lithium-based compounds selected from LiPO2F2, LiTFSI, LiFSI, LiDFOB, LiBOB, or combinations thereof.

[0014] In some embodiments, the one or more lithium-based compounds are present in an amount of about 0.1 to about 2 weight percent based on the total weight of the electrolyte composition.

[0015] In some embodiments, the co-additive includes one or more phosphorous- and silicon-based additives selected from tris(trimethylsilyl) phosphite, tris(trimethylsilyl) phosphate, or combinations thereof.

[0016] In some embodiments, the one or more phosphorous- and silicon-based additives are present in an amount of about 0.1 to about 2 weight percent based on the total weight of the electrolyte composition.

[0017] In some embodiments, the solvent is selected from fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, 3,3,3-trifluoropropylene carbonate, or combinations thereof.

[0018] A battery is provided in accordance with one or more embodiments. The battery includes an anode and a lithium- and manganese-rich layered oxide (LMR) cathode. An electrolyte composition is located between the anode and the LMR cathode. The electrolyte composition includes a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, Li salt derivatives thereof, or combinations thereof.

[0019] In some embodiments, the LMR cathode includes LixMnyNiZO2, where x is 1.1 to 1.5, y is 0.8 to 0.6, and z is 0.2 to 0.4.

[0020] In some embodiments, the LMR cathode further includes LFMP, LFP, NCMA, NMC, NCA, LNMO, or combinations thereof.

[0021] In some embodiments, the anode includes SiOx / graphite, graphite, Si, SiOx, lithium metal, or combinations thereof, and where x is a value greater than 0.

[0022] In some embodiments, the anode and LMR cathode have a negative to positive (N / P) ratio of about 1 to about 3.

[0023] In some embodiments, the battery is configured to operate within a voltage window of about 2.0 to about 5.0 V.

[0024] In some embodiments, the battery is configured to be charged at a charge rate of about C / 100 to about 6C.

[0025] A device according to one or more embodiments is provided. The device includes an output component and a battery configured to provide electrical energy to the output component. The battery includes an anode and a lithium and manganese rich layered oxide (LMR) cathode. An electrolyte composition is located between the anode and the LMR cathode. The electrolyte composition includes a solvent selected from a fluorinated ethylene carbonate, dimethyl carbonate, ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, 3,3,3-trifluoropropylene carbonate, or a combination thereof. The electrolyte composition further includes a partially substituted phosphite additive selected from a mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, a Li salt derivative thereof, or a combination thereof. The partially substituted phosphite additive is present in an amount of about 0.1 to about 5 weight percent based on the total weight of the electrolyte composition.

[0026] The following embodiments are disclosed:

[0027] 1. An electrolyte composition for a battery, the electrolyte composition comprising:

[0028] a solvent; and

[0029] a partially substituted phosphite additive selected from a mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, a Li salt derivative thereof, or a combination thereof.

[0030] 2. The electrolyte composition of embodiment 1, wherein the Li salt derivative thereof is lithium bis(trimethylsilyl) phosphate.

[0031] 3. The electrolyte composition of embodiment 1, wherein the partially substituted phosphite additive is bis(trimethylsilyl) phosphite.

[0032] 4. The electrolyte composition of embodiment 1, wherein the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 weight percent based on the total weight of the electrolyte composition.

[0033] 5. The electrolyte composition according to embodiment 1, wherein the partially substituted phosphite additive is present in an amount of about 1 to about 5 wt.%, based on the total weight of the electrolyte composition.

[0034] 6. The electrolyte composition according to embodiment 1, wherein the partially substituted phosphite additive is present in an amount of about 2 to about 4 wt.%, based on the total weight of the electrolyte composition.

[0035] 7. The electrolyte composition according to embodiment 1, further comprising a co-additive.

[0036] 8. The electrolyte composition according to embodiment 7, wherein the co-additive comprises one or more lithium-based compounds selected from LiP02F2, LiTFSI, LiFSI, LiDFOB, LiBOB or combinations thereof.

[0037] 9. The electrolyte composition according to embodiment 8, wherein the one or more lithium-based compounds are present in an amount of about 0.1 to about 2 wt.%, based on the total weight of the electrolyte composition.

[0038] 10. The electrolyte composition according to embodiment 7, wherein the co-additive comprises one or more phosphorous and silicon-based additives selected from tris(trimethylsilyl) phosphite, tris(trimethylsilyl) phosphate or combinations thereof.

[0039] 11. The electrolyte composition according to embodiment 10, wherein the one or more phosphorous and silicon-based additives are present in an amount of about 0.1 to about 2 wt.%, based on the total weight of the electrolyte composition.

[0040] 12. The electrolyte composition according to embodiment 10, wherein the solvent is selected from fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, 3,3,3-trifluoropropylene carbonate or combinations thereof.

[0041] 13. A battery comprising:

[0042] an anode;

[0043] a lithium and manganese rich layered oxide (LMR) cathode; and

[0044] an electrolyte composition positioned between the anode and the LMR cathode, the electrolyte composition comprising:

[0045] a solvent; and

[0046] a partially substituted phosphite additive selected from the group consisting of mono(trimethylsilyl)phosphite, bis(trimethylsilyl)phosphite, Li salt derivatives thereof, or combinations thereof.

[0047] 14. The battery of embodiment 13, wherein the LMR cathode comprises LixMnyNiZO2, wherein x is 1.1 to 1.5, y is 0.8 to 0.6, and z is 0.2 to 0.4.

[0048] 15. The battery of embodiment 14, wherein the LMR cathode further comprises LFMP, LFP, NCMA, NMC, NCA, LNMO, or combinations thereof.

[0049] 16. The battery of embodiment 13, wherein the anode comprises SiOx / graphite, graphite, Si, SiOx, lithium metal, or combinations thereof, and wherein x is a value greater than 0.

[0050] 17. The battery of embodiment 13, wherein the anode and LMR cathode have a negative to positive (N / P) ratio of about 1 to about 3.

[0051] 18. The battery of embodiment 13, wherein the battery is configured to operate within a voltage window of about 2.0 to about 5.0 V.

[0052] 19. The battery of embodiment 13, wherein the battery is configured to be charged at a charge rate of about C / 100 to about 6C.

[0053] 20. An apparatus comprising:

[0054] an output component; and

[0055] a battery configured to provide electrical energy to the output component, wherein the battery comprises:

[0056] an anode;

[0057] a lithium and manganese rich layered oxide (LMR) cathode; and

[0058] an electrolyte composition positioned between the anode and the LMR cathode, wherein the electrolyte composition comprises:

[0059] a solvent, wherein the solvent is selected from the group consisting of fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, 3,3,3-trifluoropropylene carbonate, or combinations thereof; and

[0060] a partially substituted phosphite additive selected from mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, Li salt derivatives thereof, or combinations thereof, wherein the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 weight percent, based on the total weight of the electrolyte composition.

[0061] The above features and advantages of the present disclosure, and other features and advantages of the present disclosure, will be more clearly understood and appreciated from the following detailed description of the best modes of the present disclosure, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 An exemplary battery cell including an anode, a cathode, a separator, and an electrolyte composition according to the present disclosure is schematically illustrated;

[0063] Figure 2 An exemplary device including a battery pack including a plurality of battery cells according to the present disclosure is schematically illustrated;

[0064] Figure 3 is a graph showing exemplary test results comparing the capacity retention of battery cells vs. the number of charge / discharge cycles of the battery cells when operated at 4.4 volts (V) with a plurality of different electrolyte compositions according to the present disclosure; and

[0065] Figure 4 is a graph showing exemplary test results comparing the capacity retention of battery cells vs. the number of charge / discharge cycles of the battery cells when operated at 4.6 V with a plurality of different electrolyte compositions according to the present disclosure. DETAILED DESCRIPTION

[0066] Detailed implementations of the present disclosure are disclosed herein as desired; however, it is to be understood that the disclosed implementations are merely exemplary of the present disclosure, which can be embodied in various and alternative forms. The Figures are not necessarily to scale; some features can be exaggerated or minimized for the purpose of clarity. The specific structural and functional details disclosed herein are not to be interpreted as limiting, but are merely representative bases for teaching one skilled in the art to variously employ the present disclosure.

[0067] The term "about" as used herein, unless otherwise expressly specified, is understood to mean that the term is in the normal tolerance range of the art, for example, within 2 standard deviations of the mean. "About" can be understood to mean within 10%, 5%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. "About" can also be understood to imply that the exact value is intended. Numerical values provided herein are modified by the term "about" unless otherwise explicitly indicated.

[0068] High capacity and high power lithium (Li) and manganese (n) rich layered oxide (LMR) cathode materials can be used in lithium ion energy storage systems to power battery electric vehicles. Such energy storage systems can be described as high energy density battery packs. The battery pack cells can include anodes containing silicon and / or graphite and LMR cathodes.

[0069] The capacity and cycle tolerance of the battery pack cells can vary depending on the operating conditions. The battery pack cell performance can vary depending on the selection of the cathode and anode materials. The electrolyte compositions disclosed herein provide excellent cycle life for the battery pack cells. In one embodiment, the electrolyte composition includes a solvent and a partially substituted phosphite additive. The partially substituted phosphite additive is selected from mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite, Li salt derivatives thereof, or a combination thereof. In one or more embodiments of the present disclosure, the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 wt. % based on the total weight of the electrolyte composition.

[0070] Testing has shown that the addition of the weight percentage of the partially substituted phosphite additive improves the formation of a solid electrolyte interface (SEI) on one or more electrodes, such as the LMR cathode, and forms an excellent protective layer on both the LMR cathode and the anode. The SEI can form on the surface of the LMR cathode. The SEI is produced from a chemical reaction between the LMR cathode and the liquid or gel electrolyte that interacts with the cathode. The SEI forms as a film on the LMR cathode and has been found to improve the cycle life of the battery pack cell.

[0071] Referring to the drawings, wherein like reference numbers refer to like features throughout the several views, Figure 1 An exemplary battery pack cell 100 is schematically shown, including an anode 110, a cathode 120, a separator 130, and an electrolyte composition 140. The battery pack cell 100 is capable of converting electrical energy into stored chemical energy in a charge cycle, and the battery pack cell 100 is capable of converting stored chemical energy into electrical energy in a discharge cycle. A negative current collector 112 is shown connected to the anode 110, and a positive current collector 122 is shown connected to the cathode 120. The separator 130 can be used to separate the anode 110 from the cathode 120, and is capable of allowing the transport of ions through the separator 130. The electrolyte composition 140 is a liquid or gel that provides a lithium ion conduction path between the anode 110 and the cathode 120.

[0072] Anode 110 can be composed of silicon, silicon alloys, or other silicon- containing materials (e.g., SiOx, where x is a value greater than 0) and / or graphite or graphite- containing materials and / or lithium metal. Cathode 120 can be composed of a lithium- and manganese-rich layered oxide (LMR) cathode active material. In one embodiment, cathode 120 is an LMR cathode that includes a LMR cathode active material having a chemical formula of Li x Mn y Ni z O2, where x is 1.1 to 1.5, y is 0.8 to 0.6, and z is 0.2 to 0.4. The LMR cathode can also include other cathode active materials such as, for example, LFMP (lithium manganese iron phosphate), LFP (lithium iron phosphate, e.g., LiFePO4), NCMA (nickel manganese cobalt aluminum oxide), NMC (nickel manganese cobalt oxide), NCA (nickel cobalt aluminum oxide), and / or LNMO (e.g., sharp crystal LiNi 0.5 Mn 1.5 O4). In an exemplary embodiment, the LMR cathode includes or has about 92 wt.% or more of the cathode active material, with a loading of about 10 to about 30 mg / cm2per unit area. 2 In an exemplary embodiment, anode 110 and cathode 120 have a negative-to-positive (N / P) ratio of about 1 to about 3.

[0073] In one or more embodiments of the disclosure, electrolyte composition 140 includes a solvent and a partially substituted phosphite additive selected from mono(trimethylsilyl) phosphite, bis(trimethylsilyl) phosphite (BTMSPi), a Li salt derivative thereof, or a combination thereof. As shown in Formula I, in an exemplary embodiment, the partially substituted phosphite additive has a chemical formula I, where when x = hydrogen (H), Formula I defines the chemical structure of bis(trimethylsilyl) phosphite, and when x = lithium (Li), Formula I defines the chemical structure of lithium bis(trimethylsilyl) phosphate, which is a Li salt derivative of bis(trimethylsilyl) phosphite. In one exemplary embodiment, the partially substituted phosphite additive is present in an amount of about 0.1 to about 5 wt.%, e.g., about 1 to about 5 wt.%, e.g., about 2 to about 4 wt.%, e.g., about 3 wt.%, based on the total weight of electrolyte composition 140. Figure 1

[0074] ​The electrolyte composition 140 can also include other co-additives. Non-limiting examples of various co-additives include one or more lithium-based compounds and / or one or more phosphorus- and silicon-based additives. Non-limiting examples of lithium-based compounds include LiPO2F2 (lithium difluorophosphate), LiTFSI (lithium bis(trifluoromethane)sulfonimide), LiFSI (lithium bis(fluorosulfonyl)imide), LiDFOB (lithium difluoro(oxalato)borate), and / or LiBOB (lithium bis(oxalato)borate). In an example embodiment, the one or more lithium-based compounds are present in an amount of about 0.1 to about 2 wt. % based on the total weight of the electrolyte composition 140. Non-limiting examples of phosphorus- and silicon-based additives include tris(trimethylsilyl)phosphite and / or tris(trimethylsilyl)phosphate. In one example embodiment, the one or more phosphorus- and silicon-based additives are present in an amount of about 0.1 to about 2 wt. % based on the total weight of the electrolyte composition 140.

[0075] Non-limiting examples of solvents in the electrolyte composition 140 include fluoroethylene carbonate, dimethyl carbonate, ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate, methyl 2,2,2-trifluoroethyl carbonate, bis(2,2,2-trifluoroethyl) carbonate, and / or 3,3,3-trifluoropropylene carbonate. In one example, the solvent includes cyclic carbonates, such as ethylene carbonate (EC), and linear carbonates, such as dimethyl carbonate.

[0076] In an example embodiment, the battery cell 100 is configured to operate within a voltage window of about 2.0 to about 5.0 V. In an example embodiment, the battery cell 100 is configured to be charged at a charge rate of about C / 100 to about 6C.

[0077] The battery cell 100 can be used in a wide variety of applications and power systems. Figure 2 An example device 200, such as a battery electric vehicle (BEV), is schematically illustrated as including a battery pack 210 that includes a plurality of battery cells 100. The plurality of battery cells 100 can be connected in various combinations, such as a portion connected in parallel and a portion connected in series, to achieve a target that supplies electrical energy at a desired voltage. The battery pack 210 is illustrated as electrically connected to a motor-generator unit 220 that is used to power the vehicle 200. The motor-generator unit 220 can include an output member, such as an output shaft, that provides mechanical energy used to power the vehicle 200. Numerous variations of the vehicle 200 are contemplated and the present disclosure is not intended to be limited to the examples provided.

[0078] Figure 3is a graph 300 of exemplary test results showing the relationship between the discharge capacity retention of battery cells and the number of charge / discharge cycles to which the battery cells were subjected. The vertical axis 304 is shown to describe the discharge capacity in mAh / cm 2 The vertical axis 305 is shown to describe the discharge capacity retention in percent (%). The horizontal axis 302 is shown to describe the number of charge / discharge cycles. As shown, line 310 represents the baseline electrolyte composition, line 312 represents the baseline electrolyte composition modified with 1% TTMSPi, and line 314 represents the baseline electrolyte composition modified with 1% BTMSPi, all at a higher initial discharge capacity. Likewise, line 320 represents the baseline electrolyte composition, line 322 represents the baseline electrolyte composition modified with 1% TTMSPi, and line 324 represents the baseline electrolyte composition modified with 1% BTMSPi, all at a lower initial discharge capacity. As shown in graph 300, the electrolyte containing the bis-phosphite additive (BTMSPi) exhibited superior cycle life performance than the baseline or conventional trimethylsilyl phosphite additive (TTMSPi) system when cycled at a 4.4 V upper cutoff voltage.

[0079] Figure 4 is a graph 400 of exemplary test results showing the relationship between the capacity retention of battery cells and the number of charge / discharge cycles to which the battery cells were subjected. The vertical axis 404 is shown to describe the discharge capacity in mAh / cm 2 The vertical axis 405 is shown to describe the discharge capacity retention in percent (%). The horizontal axis 402 is shown to describe the number of charge / discharge cycles. As shown, line 410 represents the baseline electrolyte composition, line 412 represents the baseline electrolyte composition modified with 1% BTMSPi, and line 414 represents the baseline electrolyte composition modified with 3% BTMSPi, all at a higher initial discharge capacity. Likewise, line 420 represents the baseline electrolyte composition, line 422 represents the baseline electrolyte composition modified with 1% BTMSPi, and line 424 represents the baseline electrolyte composition modified with 3% BTMSPi, all at a lower initial discharge capacity. As shown in graph 400, even when cycled at a higher cutoff voltage of 4.6 V, the bis-phosphite additive (BTMSPi) exhibited superior cycle life performance than the baseline electrolyte (containing no additive). Moreover, the performance at high voltage depends on the actual concentration of the bis-phosphite additive (BTMSPi). Increasing the concentration from 1% to 3% significantly improved the cycle performance at 4.6 V.

[0080] While the best mode for carrying out the disclosure has been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments, within the scope of the following claims, for practicing the disclosure.

Claims

1. An electrolyte composition for a battery pack, said electrolyte composition comprising: Solvent; and Partially substituted phosphite additives are selected from mono(trimethylsilyl)phosphites, bis(trimethylsilyl)phosphites, their Li salt derivatives, or combinations thereof.

2. The electrolyte composition according to claim 1, wherein its Li salt derivative is lithium bis(trimethylsilyl)phosphate.

3. The electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is bis(trimethylsilyl)phosphite.

4. The electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is present in an amount of about 0.1 to about 5% by weight, based on the total weight of the electrolyte composition.

5. The electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is present in an amount of about 1 to about 5% by weight, based on the total weight of the electrolyte composition.

6. The electrolyte composition according to claim 1, wherein the partially substituted phosphite additive is present in an amount of about 2 to about 4% by weight, based on the total weight of the electrolyte composition.

7. The electrolyte composition according to claim 1, further comprising an additive.

8. The electrolyte composition according to claim 7, wherein the co-additive comprises one or more lithium-based compounds selected from LiPO2F2, LiTFSI, LiFSI, LiDFOB, LiBOB, or combinations thereof.

9. The electrolyte composition of claim 8, wherein the amount of the one or more lithium-based compounds present, based on the total weight of the electrolyte composition, is from about 0.1 to about 2% by weight.

10. The electrolyte composition of claim 7, wherein the co-additive comprises one or more phosphorus-based and silicon-based additives selected from tris(trimethylsilyl)phosphite, tris(trimethylsilyl)phosphate, or combinations thereof.

Images