Fluorinated phosphate ester additives for electrolytes of batteries comprising lithium manganese rich positive electrodes

Abstract

The invention relates to a fluorinated phosphate ester additive for an electrolyte of a battery comprising a lithium manganese rich positive electrode. A battery circulating lithium ions includes a positive electrode and an electrolyte infiltrating the positive electrode. The positive electrode comprises an electroactive material comprising a layered lithium transition metal oxide. The electrolyte includes an organic solvent, a lithium salt, and a fluorinated phosphate additive. The fluorinated phosphate ester comprises at least one of (i) a compound comprising a phosphate ester group attached to two or three branched fluorocarbon groups, or (ii) a compound comprising a cyclic phosphate ester group attached to a fluorocarbon group.

Description

Technical Field

[0001] The present disclosure relates to electrolytes for cycling lithium ion batteries and more particularly to additives for electrolytes for batteries that promote the formation of a protective interfacial layer on the surface of an electrode material. Background Art

[0002] The information provided in this section is intended to generally introduce the background of the present disclosure. To the extent that work currently named as inventors is described in this section, and aspects of the specification that may not have been otherwise identified as prior art at the time of filing, are not admitted, either explicitly or implicitly, as prior art to the present disclosure.

[0003] Batteries that cycle lithium ions typically include a positive electrode, a negative electrode spaced apart from the positive electrode, and an ion-conductive electrolyte that provides a medium for the conduction of lithium ions between the positive electrode and the negative electrode during discharge and charge of the battery. The electrolyte can be formulated to exhibit certain desirable properties, including high ionic conductivity, high dielectric constant (related to a high ability to dissolve salts), good thermal stability, a wide electrochemical stability window, the ability to form a stable ion-conductive solid electrolyte interface on the surface of the positive electrode and / or the negative electrode, and chemical compatibility with the other components of the battery. Summary of the invention

[0004] According to one or more embodiments of the present disclosure, a battery pack for circulating lithium ions includes a positive electrode and an electrolyte infiltrated into the positive electrode. The positive electrode comprises an electroactive material comprising a layered lithium transition metal oxide. The electrolyte comprises an organic solvent, a lithium salt in the organic solvent, and a fluorinated phosphate additive in the organic solvent. The fluorinated phosphate additive comprises at least one of the following: (i) a compound comprising a phosphate group connected to two or three branched fluorocarbon groups, or (ii) a compound comprising a cyclic phosphate group connected to a fluorocarbon group.

[0005] The fluorinated phosphate additive may include a fluorinated phosphate triester having the formula (1):

[0006]

[0007] Where X 1 , X 2 , X 3 , X 4 , X 5 and X 6 are each independently a fluorocarbon group, R 1 , R 2 , R 3 , R 4 , R5 and R 6 are each independently a fluorinated or non-fluorinated divalent hydrocarbon group, and Y 1 , Y 2 and Y 3 are each independently hydrogen (H) or fluorine (F).

[0008] The fluorinated phosphate additive may include tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate, tris(1,1,1,5,5,5-hexafluoropentan-3-yl) phosphate, tris(1,1,1,2,3,3,3-heptafluoropropane-2-yl) phosphate, or a combination thereof.

[0009] The fluorinated phosphate additive may include a fluorinated cyclic phosphate having formula (2):

[0010]

[0011] Where R 1 is a non-fluorinated divalent hydrocarbon group, R 2 is a fluorinated or non-fluorinated divalent hydrocarbon group, and X is a fluorocarbon group.

[0012] The fluorinated phosphate additive may include 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide.

[0013] The fluorinated phosphate additive may comprise greater than or equal to about 0.5 wt % to less than or equal to about 2.5 wt % of the electrolyte.

[0014] In some aspects, the electroactive material of the positive electrode may include a layered lithium-rich manganese transition metal oxide, and the organic solvent may include a mixture of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC). In such cases, the lithium salt may include lithium hexafluorophosphate (LiPF6), and the electrolyte may further include lithium difluorophosphate (LiPO2F2). The fluorinated phosphate additive may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte, and LiPO2F2 may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte.

[0015] In some aspects, the electroactive material of the positive electrode may include a layered lithium-rich nickel transition metal oxide, and the organic solvent may include a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). In such cases, the lithium salt may include lithium hexafluorophosphate (LiPF6) and lithium difluoro(oxalato)borate (LiDFOB), and the electrolyte may further include fluoroethylene carbonate (FEC) and vinylene carbonate (VC). The fluorinated phosphate additive may account for greater than or equal to about 1.5% by weight to less than or equal to about 2.5% by weight of the electrolyte, LiDFOB may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte, FEC may account for greater than or equal to about 1.5% by weight to less than or equal to about 2.5% by weight of the electrolyte, and VC may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte.

[0016] During cycling of the battery, the fluorinated phosphate ester additive may decompose and form an interfacial layer on the surface of the electroactive material of the positive electrode, the interfacial layer separating the electroactive material from physical contact with the electrolyte.

[0017] The battery pack may further include an interfacial layer formed in situ on the electroactive material of the positive electrode during cycling of the battery pack. The interfacial layer may include electrochemical decomposition products of the fluorinated phosphate additive. The interfacial layer may physically separate the electroactive material of the positive electrode from contact with the electrolyte.

[0018] According to one or more embodiments of the present disclosure, a battery pack for circulating lithium ions includes a positive electrode, a negative electrode, and an electrolyte infiltrated into the positive electrode and the negative electrode. The positive electrode comprises an electroactive material containing a layered lithium transition metal oxide. The negative electrode comprises an electroactive material containing silicon oxide, lithiated silicon oxide, graphite, or a combination thereof. The electrolyte comprises an organic solvent, a lithium salt in the organic solvent, and a fluorinated phosphate additive in the organic solvent. The organic solvent comprises a cyclic carbonate and a linear carbonate. The fluorinated phosphate additive comprises at least one of the following: (i) a compound comprising a phosphate group connected to two or three branched fluorocarbon groups, or (ii) a compound comprising a cyclic phosphate group connected to a fluorocarbon group.

[0019] The fluorinated phosphate additive may include a fluorinated phosphate triester having the formula (1):

[0020]

[0021] Where X 1 , X 2 , X 3, X 4 , X 5 and X 6 are each independently a fluorocarbon group, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a fluorinated or non-fluorinated divalent hydrocarbon group, and Y 1 , Y 2 and Y 3 are each independently hydrogen (H) or fluorine (F).

[0022] The fluorinated phosphate additive may include tris(1,1,1,3,3,3-hexafluoropropan-2-yl)phosphate, tris(1,1,1,5,5,5-hexafluoropentan-3-yl)phosphate, tris(1,1,1,2,3,3,3-heptafluoropropane-2-yl)phosphate, or a combination thereof.

[0023] The fluorinated phosphate additive may include a fluorinated cyclic phosphate having formula (2):

[0024]

[0025] Where R 1 is a non-fluorinated divalent hydrocarbon group, R 2 is a fluorinated or non-fluorinated divalent hydrocarbon group, and X is a fluorocarbon group.

[0026] The fluorinated phosphate additive may include 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide.

[0027] The fluorinated phosphate additive may comprise greater than or equal to about 0.5 wt % to less than or equal to about 2.5 wt % of the electrolyte.

[0028] In some aspects, the electroactive material of the positive electrode may include a layered lithium-rich manganese transition metal oxide, the organic solvent may include a mixture of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC), the lithium salt may include lithium hexafluorophosphate (LiPF6), and the electrolyte may further include lithium difluorophosphate (LiPO2F2). In such cases, the fluorinated phosphate additive may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte, and LiPO2F2 may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte.

[0029] In some aspects, the electroactive material of the positive electrode may include a layered lithium-rich nickel transition metal oxide, the organic solvent may include a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC), the lithium salt may include lithium hexafluorophosphate (LiPF6) and lithium difluoro(oxalato)borate (LiDFOB), and the electrolyte may further include fluoroethylene carbonate (FEC) and vinylene carbonate (VC). In such cases, the fluorinated phosphate additive may account for greater than or equal to about 1.5% by weight to less than or equal to about 2.5% by weight of the electrolyte, LiDFOB may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte, FEC may account for greater than or equal to about 1.5% by weight to less than or equal to about 2.5% by weight of the electrolyte, and VC may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte.

[0030] The battery pack may further include a first interface layer disposed on the electroactive material of the positive electrode, the first interface layer physically separating the contact between the electroactive material of the positive electrode and the electrolyte, and a second interface layer disposed on the electroactive material of the negative electrode, the second interface layer physically separating the contact between the electroactive material of the negative electrode and the electrolyte, the first interface layer and the second interface layer may be formed in situ during cycling of the battery pack. The first interface layer and the second interface layer may contain decomposition products of the fluorinated phosphate additive.

[0031] The present invention discloses the following scheme:

[0032] Solution 1. A circulating lithium ion battery pack, the battery pack comprising:

[0033] a positive electrode comprising an electroactive material comprising a layered lithium transition metal oxide; and

[0034] An electrolyte infiltrated into the positive electrode, the electrolyte comprising:

[0035] Organic solvents;

[0036] a lithium salt in the organic solvent; and

[0037] A fluorinated phosphate additive in the organic solvent, the fluorinated phosphate additive comprising at least one of the following:

[0038] (i) a compound comprising a phosphate group attached to two or three branched fluorocarbon groups, or

[0039] (ii) Compounds comprising a cyclic phosphate group linked to a fluorocarbon group.

[0040] Option 2. A battery according to Option 1, wherein the fluorinated phosphate ester additive comprises a fluorinated phosphate triester having formula (1):

[0041]

[0042] Where X 1 , X 2 , X 3 , X 4 , X 5 and X 6 are each independently a fluorocarbon group, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a fluorinated or non-fluorinated divalent hydrocarbon group, and Y 1 , Y 2 and Y 3 are each independently hydrogen (H) or fluorine (F).

[0043] Option 3. A battery according to Option 2, wherein the fluorinated phosphate additive comprises tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate, tris(1,1,1,5,5,5-hexafluoropentan-3-yl) phosphate, tris(1,1,1,2,3,3,3-heptafluoropropane-2-yl) phosphate, or a combination thereof.

[0044] Option 4. A battery according to Option 1, wherein the fluorinated phosphate additive comprises a fluorinated cyclic phosphate having formula (2):

[0045]

[0046] Where R 1 is a non-fluorinated divalent hydrocarbon group, R 2 is a fluorinated or non-fluorinated divalent hydrocarbon group, and X is a fluorocarbon group.

[0047] Embodiment 5. The battery pack according to embodiment 4, wherein the fluorinated phosphate additive comprises 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide.

[0048] Embodiment 6. The battery pack of Embodiment 1, wherein the fluorinated phosphate ester additive comprises greater than or equal to about 0.5 wt % to less than or equal to about 2.5 wt % of the electrolyte.

[0049] Option 7. A battery according to Option 1, wherein the electroactive material of the positive electrode comprises a layered lithium-rich manganese transition metal oxide, and wherein the organic solvent comprises a mixture of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC).

[0050] Option 8. A battery according to Option 7, wherein the lithium salt comprises lithium hexafluorophosphate (LiPF6), and wherein the electrolyte further comprises lithium difluorophosphate (LiPO2F2).

[0051] Option 9. A battery pack according to Option 8, wherein the fluorinated phosphate additive accounts for greater than or equal to about 0.5 wt. % to less than or equal to about 1.5 wt. % of the electrolyte, and wherein LiPO2F2 accounts for greater than or equal to about 0.5 wt. % to less than or equal to about 1.5 wt. % of the electrolyte.

[0052] Option 10. A battery according to Option 1, wherein the electroactive material of the positive electrode comprises a layered lithium-rich nickel transition metal oxide, and wherein the organic solvent comprises a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC).

[0053] Option 11. A battery according to Option 10, wherein the lithium salt comprises lithium hexafluorophosphate (LiPF6) and lithium difluoro(oxalato)borate (LiDFOB), and wherein the electrolyte further comprises fluoroethylene carbonate (FEC) and vinylene carbonate (VC).

[0054] Embodiment 12. A battery pack according to Embodiment 11, wherein the fluorinated phosphate additive accounts for greater than or equal to about 1.5 weight % to less than or equal to about 2.5 weight % of the electrolyte, LiDFOB accounts for greater than or equal to about 0.5 weight % to less than or equal to about 1.5 weight % of the electrolyte, FEC accounts for greater than or equal to about 1.5 weight % to less than or equal to about 2.5 weight % of the electrolyte, and VC accounts for greater than or equal to about 0.5 weight % to less than or equal to about 1.5 weight % of the electrolyte.

[0055] Solution 13. A circulating lithium ion battery pack, the battery pack comprising:

[0056] a positive electrode comprising an electroactive material comprising a layered lithium transition metal oxide;

[0057] a negative electrode comprising an electroactive material comprising silicon oxide, lithiated silicon oxide, graphite, or a combination thereof; and

[0058] An electrolyte infiltrated into the positive electrode and the negative electrode, the electrolyte comprising:

[0059] Organic solvents containing cyclic carbonates and linear carbonates;

[0060] a lithium salt in the organic solvent; and

[0061] A fluorinated phosphate additive in the organic solvent, the fluorinated phosphate additive comprising at least one of the following:

[0062] (i) a compound comprising a phosphate group attached to two or three branched fluorocarbon groups, or

[0063] (ii) Compounds comprising a cyclic phosphate group linked to a fluorocarbon group.

[0064] Embodiment 14. The battery pack according to embodiment 13, wherein the fluorinated phosphate ester additive comprises a fluorinated phosphate triester having formula (1):

[0065]

[0066] Where X 1 , X 2 , X 3 , X 4 , X 5 and X 6 are each independently a fluorocarbon group, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a fluorinated or non-fluorinated divalent hydrocarbon group, and Y 1 , Y 2 and Y 3 are each independently hydrogen (H) or fluorine (F).

[0067] Option 15. A battery according to Option 14, wherein the fluorinated phosphate additive comprises tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate, tris(1,1,1,5,5,5-hexafluoropentan-3-yl) phosphate, tris(1,1,1,2,3,3,3-heptafluoropropane-2-yl) phosphate, or a combination thereof.

[0068] Embodiment 16. The battery pack according to Embodiment 13, wherein the fluorinated phosphate ester additive comprises a fluorinated cyclic phosphate ester having formula (2):

[0069]

[0070] Where R 1 is a non-fluorinated divalent hydrocarbon group, R 2 is a fluorinated or non-fluorinated divalent hydrocarbon group, and X is a fluorocarbon group.

[0071] Embodiment 17. The battery pack according to embodiment 16, wherein the fluorinated phosphate additive comprises 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide.

[0072] Embodiment 18. The battery pack of embodiment 13, wherein the fluorinated phosphate ester additive constitutes greater than or equal to about 0.5 weight % and less than or equal to about 2.5 weight % of the electrolyte.

[0073] Option 19. A battery pack according to Option 13, wherein the electroactive material of the positive electrode comprises a layered lithium-rich manganese transition metal oxide, the organic solvent comprises a mixture of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC), the lithium salt comprises lithium hexafluorophosphate (LiPF6), and the electrolyte further comprises lithium difluorophosphate (LiPO2F2), and wherein the fluorinated phosphate additive accounts for greater than or equal to about 0.5 weight % to less than or equal to about 1.5 weight % of the electrolyte, and LiPO2F2 accounts for greater than or equal to about 0.5 weight % to less than or equal to about 1.5 weight % of the electrolyte.

[0074] Option 20. A battery pack according to Option 13, wherein the electroactive material of the positive electrode comprises a layered lithium-rich nickel transition metal oxide, the organic solvent comprises a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC), the lithium salt comprises lithium hexafluorophosphate (LiPF6) and lithium difluoro(oxalato)borate (LiDFOB), and the electrolyte further comprises fluoroethylene carbonate (FEC) and vinylene carbonate (VC), and wherein the fluorinated phosphate additive accounts for greater than or equal to about 1.5 weight % to less than or equal to about 2.5 weight % of the electrolyte, LiDFOB accounts for greater than or equal to about 0.5 weight % to less than or equal to about 1.5 weight % of the electrolyte, FEC accounts for greater than or equal to about 1.5 weight % to less than or equal to about 2.5 weight % of the electrolyte, and VC accounts for greater than or equal to about 0.5 weight % to less than or equal to about 1.5 weight % of the electrolyte.

[0075] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings.The detailed description and specific examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The present disclosure will be more fully understood through the detailed description and accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The disclosure will become more fully understood from the detailed description and accompanying drawings, in which:

[0079] Figure 1 is a schematic perspective view of a motor vehicle powered by a battery pack including a plurality of battery modules.

[0080] Figure 2 yes Figure 1 Schematic cross-sectional view of a portion of one of a battery module comprising a plurality of electrochemical cells or batteries that circulate lithium ions.

[0081] Figure 3 is a schematic cross-sectional view of a battery stack for cycling lithium ions, the battery stack including a positive electrode, a negative electrode, a porous separator, and an electrolyte that permeates the positive and negative electrodes and the porous separator.

[0082] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0083] The electrolyte disclosed in the present invention is formulated for use in a lithium-ion battery pack and includes a layered lithium transition metal oxide as a positive electrode material, which can operate at ultra-high voltages (e.g., relative to Li + / Li>4.4V). The electrolyte disclosed in the present invention includes a fluorinated phosphate ester additive, and the nitrile additive is formulated to decompose during the cycling of the battery pack to form a protective interface layer surface of the positive electrode material and the negative electrode material. The protective interface layer formed by the fluorinated phosphate ester additive helps to separate the physical contact between the positive electrode and the negative electrode material and the electrolyte, which can help improve the cycle stability and capacity retention of the battery pack, for example, by preventing undesirable chemical reactions between the positive electrode and the negative electrode material and the electrolyte during the cycling of the battery pack.

[0084] Figure 1 A motor vehicle 2 is depicted that is powered by an electric motor 4 that draws power from a battery 6 that includes one or more battery modules 8. The battery modules 8 may be electrically connected together in a series and / or parallel arrangement to meet the desired capacity and power requirements of the electric motor 4. The vehicle 2 may be an all-electric vehicle and may be powered solely by the electric motor 4, or the vehicle 2 may be a hybrid electric vehicle and may be powered by both the electric motor 4 and an internal combustion engine (not shown).

[0085] like Figure 2As shown in , each battery module 8 includes one or more electrochemical cells or batteries 10 that circulate lithium ions. In practice, the batteries 10 in the battery module 8 are often assembled as stacked layers, which include a negative electrode layer 12, a negative electrode current collector 13, a positive electrode layer 14, a positive electrode current collector 15 and a separator layer 16. Each battery 10 is defined by a negative electrode layer 12 and a positive electrode layer 14, which are separated from each other by a separator layer 16. The negative electrode layer 12 is disposed on and electrically connected to the negative electrode current collector 13, and the positive electrode layer 14 is disposed on and electrically connected to the positive electrode current collector 15. As shown in Figure 2 As shown in , for efficiency, the layers may be stacked so that some of the negative electrode current collectors 13 and the positive electrode current collectors 15 are double-sided and contain negative electrode layers 12 or positive electrode layers 14 on both sides thereof. In such an arrangement, adjacent negative electrode layers 12 and positive electrode layers 14 share a single negative electrode current collector 13 or positive electrode current collector 15.

[0086] Figure 3 An electrochemical cell or battery 20 of circulating lithium ions is depicted. The battery 20 can generate an electric current during discharge that can be used to power a load device (e.g., an electric motor 4), and can be recharged by connection to a power source. Figure 1 and Figure 2 Similar to the battery pack 10 depicted in FIG. 2 , in some aspects, the battery pack 20 may be used to power the electric motor 4 of the motor vehicle 2. Additionally or alternatively, the battery pack 20 may be used in other transportation applications (e.g., motorcycles, boats, tractors, buses, motorbikes, mobile homes, campers, tanks, and aircraft), and may be used to power stationary and / or mobile electronic devices, components, and devices used in various other industries and applications, including, by way of non-limiting example, industrial, residential and commercial construction, consumer products, industrial equipment and machinery, agricultural or farm equipment, and heavy machinery.

[0087] The battery 20 includes a negative electrode 22, a positive electrode 24, a separator 26, and an electrolyte 28 that wets the surfaces of the negative electrode 22, the positive electrode 24, and the separator 26. The negative electrode 22 is disposed on a negative electrode current collector 30, and the positive electrode 24 is disposed on a positive electrode current collector 32. In practice, the negative electrode current collector 30 and the positive electrode current collector 32 are electrically connected to a power source or load 34 (e.g., a motor 12) via an external circuit 36. The negative electrode 22 and the positive electrode 24 are configured so that an electrochemical potential difference is established between the negative electrode 22 and the positive electrode 24 when the battery 20 is at least partially charged. During discharge of the battery 20, the electrochemical potential established between the negative electrode 22 and the positive electrode 24 drives a spontaneous redox reaction within the battery 20 and the release of lithium ions and electrons at the negative electrode 22. The released lithium ions move from the negative electrode 22 to the positive electrode 24 through the separator 26 and the electrolyte 28, and the electrons move from the negative electrode 22 to the positive electrode 24 via the external circuit 36, which generates an electric current. After the negative electrode 22 has been partially or completely depleted of lithium, the battery 20 can be charged by connecting the negative electrode 22 and the positive electrode 24 to the power source 34, which drives a non-transient redox reaction within the battery 20 and the release of lithium ions and electrons from the positive electrode 24. The repeated discharge and charge of the battery 20 may be referred to herein as a "cycle," where a full charge event followed by a full discharge event is considered a full cycle.

[0088] The negative electrode 22 is configured to store and release lithium ions during charging and discharging of the battery 20. The negative electrode 22 may be in the form of a continuous layer of material disposed on a major surface of the negative electrode current collector 30. The negative electrode 22 is configured to store and release lithium ions to facilitate charging and discharging of the battery 20, respectively. To achieve this, the negative electrode 22 contains one or more electrochemically active (electroactive) materials that can facilitate the storage and release of lithium ions by sending a reversible redox reaction with lithium during charging and discharging of the battery 20. The electroactive material may account for greater than or equal to about 85% by weight, or optionally about 90% by weight to less than or equal to about 99% by weight of the negative electrode 22.

[0089] The electroactive material of the negative electrode 22 may include silicon, a silicon oxide-based material, a lithiated silicon oxide-based material, and / or a carbon-based material (e.g., graphite). For example, the electroactive material of the negative electrode 22 may include silicon oxide SiO x , where x is greater than zero (0) and less than or equal to 2. In some aspects, the electroactive material of the negative electrode 22 may include lithiated silicon oxide Li y SiO x, where x is greater than zero (0) and less than or equal to 2, and y is greater than zero (0) and less than or equal to 1. In some aspects, the electroactive material of the negative electrode 22 may include a silicon oxide-based material (e.g., Si, SiO x and / or Li y SiO x ) and carbon-based materials (e.g., graphite). In such cases, the silicon oxide-based material may account for greater than or equal to about 10% by weight to less than or equal to about 70% by weight, or optionally less than or equal to about 30% by weight of the electroactive material of the negative electrode 22, and the carbon-based material (e.g., graphite) may account for greater than or equal to about 30% by weight, or optionally about 70% by weight to less than or equal to about 90% by weight of the electroactive material of the negative electrode 22.

[0090] In some aspects, the negative electrode 22 can be porous, and the electroactive material of the negative electrode 22 can be a granular material. In such cases, the particles of the electroactive material of the negative electrode 22 can be mixed with a polymer binder and / or a conductive material. The polymer binder can provide structural integrity for the negative electrode 22. Examples of polymer binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), nitrile rubber (NBR), styrene butadiene rubber (SBR), styrene ethylene butylene styrene copolymer (SEBS), polyacrylates, alginates, polyacrylic acid and combinations thereof. The conductive material can provide good conductivity for the negative electrode 22. Examples of conductive materials include carbon-based materials, metals (e.g., nickel) and / or conductive polymers. Examples of conductive carbon-based materials include carbon black (CB) (e.g., acetylene black), graphene (e.g., graphene nanosheets GNP), graphene oxide, carbon nanotubes (CNT) and / or carbon fibers (e.g., carbon nanofibers). Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, and / or polypyrrole. In some aspects, negative electrode 22 can include a conductive material including carbon black.

[0091] The positive electrode 24 is configured to store and release lithium ions during discharge and charge of the battery pack 20. The positive electrode 24 may be in the form of a continuous porous layer disposed on a major surface of the positive electrode current collector 20. The positive electrode 24 includes one or more electrochemically active (electroactive) materials that can undergo a reversible redox reaction with lithium at a higher electrochemical potential than the electroactive material of the negative electrode 22, such that an electrochemical potential difference exists between the positive electrode 12 and the negative electrode 14. For example, the electroactive material of the positive electrode 24 may include an intercalation host material capable of reversible insertion or embedding of lithium ions. In such cases, the electroactive material of the positive electrode 24 may include a layered lithium transition metal oxide represented by the formula LiMeO2 and / or Li2MeO3, a layered lithium transition metal oxide represented by the formula Li 1+x Me 1-x O2 (where 0 < x ≤ 0.33), an olivine-type oxide represented by the formula LiMePO4, a monoclinic oxide represented by the formula Li3Me2(PO4)3, a spinel-type oxide represented by the formula LiMe2O4, a hydroxyapatite represented by one or both of the following formulas LiMeSO4F or LiMePO4F, or a combination thereof, wherein Me is a transition metal (e.g., Co, Ni, Mn, Fe, Al, V, or a combination thereof). The electroactive material of the positive electrode 24 may account for greater than or equal to about 80% by weight, optionally about 90% by weight, optionally about 95% by weight to less than or equal to about 99% by weight, or optionally about 98% by weight of the positive electrode 24.

[0092] In some aspects, the electroactive material of the positive electrode 24 may include a layered lithium-rich manganese transition metal oxide represented by the formula LiMeO2 and / or Li2MeO3, wherein Me contains greater than or equal to about 50 wt% manganese (Mn). In some aspects, the electroactive material of the positive electrode 24 may include a layered lithium-rich manganese transition metal oxide represented by the formula LiMeO2 and / or Li2MeO3, wherein Me contains greater than or equal to about 50 wt% manganese (Mn). 1+x Me 1-x O2 (where 0<x≤0.33), wherein Me contains greater than or equal to about 50 wt % manganese (Mn). In some aspects, the electroactive material of the positive electrode 24 may include a layered lithium-rich manganese oxide represented by the formula Li2MnO3. In some aspects, the electroactive material of the positive electrode 24 may include a layered lithium-rich nickel transition metal oxide represented by the formula LiMeO2 and / or Li2MeO3, wherein Me contains greater than or equal to about 50 wt % nickel (Ni). In some aspects, the electroactive material of the positive electrode 24 may include a layered lithium-rich nickel transition metal oxide represented by the formula LiMeO2 and / or Li2MeO3, wherein Me contains greater than or equal to about 50 wt % nickel (Ni). 1+x Me 1-x A layered lithium-rich manganese transition metal oxide represented by O2 (wherein 0<x≤0.33), wherein Me contains greater than or equal to about 50 wt % nickel (Ni).

[0093] In some aspects, the electroactive material of the positive electrode 24 may include lithium manganese iron phosphate (LMFP), lithium iron phosphate (LFP), spinel lithium manganese oxide (LiMn2O4, LMO), high voltage spinel (LiNi 0.5 Mn 1.5 O4, LNMO), lithium nickel cobalt manganese aluminum oxide (NCMA), lithium nickel manganese cobalt oxide (NMC), lithium nickel manganese oxide (LNMO) (such as LiNi 0.5 Mn 1.5 O4 and / or Li 1.2 Ni 0.2 Mn 0.6 O2), lithium nickel cobalt aluminum oxide (NCA), or a combination thereof.

[0094] Similar to the electroactive material of the negative electrode 22, the electroactive material of the positive electrode 24 may be a granular material, and the particles of the electroactive material of the positive electrode 24 may be mixed with particles of a polymer binder and / or a conductive material. The same polymer binder and / or conductive material disclosed above with respect to the negative electrode 22 may be used in the positive electrode 24. In some aspects, the positive electrode 24 may include a polymer binder including polyvinylidene fluoride.

[0095] The separator 26 physically separates and electrically separates the negative electrode 22 and the positive electrode 24 from each other, while allowing lithium ions to pass therethrough. The separator 26 has an open microporous structure and may include organic and / or inorganic materials. For example, the separator 26 may include a polymer or a combination of polymers. For example, the separator 26 may include one or more polyolefins, such as polyethylene (PE), polypropylene (PP), polyamide (PA), poly(tetrafluoroethylene) (PTFE), polyvinylidene fluoride (PVDF) and / or poly(vinyl chloride) (PVC). In one form, the separator 26 may include a laminate of a polymer, such as a laminate of PE and PP. In some aspects, the separator 26 may include a ceramic coating (not shown) disposed on one or both sides thereof. In such cases, the ceramic coating may include particles of aluminum oxide (Al2O3) and / or silicon dioxide (SiO2).

[0096] The electrolyte 28 is ionically conductive, provides a medium for the conduction of lithium ions between the negative electrode 22 and the positive electrode 24, and is formulated to provide enhanced cycling stability to the battery 20. The electrolyte 28 includes an organic solvent, a lithium salt, and a fluorinated phosphate additive. Figure 3 As shown in , the fluorinated phosphate ester additive is formulated to assist in forming a first interfacial layer 38 on a surface 40 of the negative electrode 22 and a second interfacial layer 42 on a surface 44 of the positive electrode 24 .

[0097] The organic solvent may include a mixture of a non-aqueous aprotic organic solvent or a non-aqueous aprotic organic solvent. Non-limiting examples of non-aqueous aprotic organic solvents include cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC)), linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylates (e.g., methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g., γ-butyrolactone, γ-valerolactone), chain structure ethers (e.g., 1,2-dimethoxyethane, 1-2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran), 1,3-dioxolane) and combinations thereof. The organic solvent may account for greater than or equal to about 70 wt % to less than or equal to about 90 wt % of the electrolyte 28. In some aspects, the organic solvent may include a mixture of cyclic carbonates and linear carbonates. For example, the organic solvent may include a mixture of FEC and DEC. In such cases, the volume ratio of FEC to DEC in the organic solvent may be about 1:4. As another example, the organic solvent may include a mixture of EC and DMC. In such cases, the volume ratio of EC to DMC in the organic solvent may be about 3:7. In the aspect that the organic solvent includes a mixture of EC and DMC, the organic solvent may further include FEC and VC. In such cases, FEC may account for greater than or equal to about 1% by weight to less than or equal to about 3% by weight of the electrolyte 28, and VC may account for greater than or equal to about 0.5% by weight to less than or equal to about 1.5% by weight of the electrolyte 28. For example, in some aspects, FEC may account for about 2% by weight of the electrolyte 28, and VC may account for about 1% by weight of the electrolyte 28.

[0098] The lithium salt is soluble in the organic solvent and provides a passage for lithium ions to pass through the electrolyte 28. The lithium salt may include an inorganic lithium salt, an organic lithium salt, or a combination thereof. Examples of inorganic lithium salts include lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPO2F2), lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonyl imide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2)(LiSFI), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2)(LiBOB), lithium difluoro(oxalato)borate (LiBF2(C2O4))(LiDFOB), and combinations thereof. The lithium salt may be dissolved in an organic solvent at a concentration of greater than or equal to about 0.5 molar to less than or equal to about 1.5 molar. In some aspects, the lithium salt may be dissolved in an organic solvent at a concentration of about 1 molar. The lithium salt may account for greater than or equal to about 5 wt% to less than or equal to about 20 wt% of the electrolyte 28. In some aspects, the lithium salt may include LiPF6. In some aspects, the lithium salt may include LiPF6 and LiPO2F2. In such cases, LiPO2F2 may account for greater than or equal to about 0.1 wt% of the electrolyte 28, or optionally about 0.5 wt% to less than or equal to about 3 wt%, or optionally about 1.5 wt%. In some aspects, LiPO2F2 may account for about 1 wt% of the electrolyte 28. In some aspects, the lithium salt may include LiPF6 and LiDFOB. In such cases, LiDFOB may account for greater than or equal to about 0.1 wt%, or optionally about 0.5 wt% to less than or equal to about 3 wt%, or optionally about 1.5 wt%, of the electrolyte 28. In some aspects, LiDFOB may comprise about 1 wt % of electrolyte 28 .

[0099] The fluorinated phosphate ester additive is formulated to aid in the formation of the first interface layer 38 and the second interface layer 42 during initial charging and / or cycling of the battery 20 .

[0100] Fluorinated phosphate additives are compounds comprising a monophosphate group connected to two or three fluorocarbon groups (i.e., fluoroalkyl, fluoroalkenyl, fluoroalkynyl, fluoroaryl, or combinations thereof). A fluorocarbon group or a fluorinated hydrocarbon group is a hydrocarbon group in which at least one of the hydrogen (H) atoms has been replaced by a fluorine (F) atom. The fluorocarbon group may be polyfluorinated, in which more than one of the H atoms has been replaced by an F atom, or the fluorocarbon group may be perfluorinated, in which all of the H atoms have been replaced by F atoms. The ratio of fluorine (F) to phosphorus (P) (F to P) in the fluorinated phosphate additive may be greater than or equal to about 3 to 1, optionally greater than or equal to about 12 to 1, or optionally greater than or equal to about 18 to 1.

[0101] In some aspects, the fluorinated phosphate additive can be a compound comprising a phosphate group connected to two or three branched fluorocarbon groups. For example, the fluorinated phosphate additive can be a fluorinated phosphate triester having the following formula (1):

[0102]

[0103] Where X 1 , X 2 , X 3 , X 4 , X 5 and X 6 are each independently a fluorocarbon group, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a fluorinated or non-fluorinated divalent hydrocarbon group, and Y 1 , Y 2 and Y 3 are each independently hydrogen (H) or fluorine (F).

[0104] X 1 , X 2 , X 3 , X 4 , X 5 and X 6 may be independently polyfluorinated or perfluorinated C1-C 10 Straight chain or branched chain alkyl, alkenyl, alkynyl, aryl, or a combination thereof. 10 Examples of alkyl groups include methyl (-CH3), ethyl (-CH2CH3), propyl (-CH2CH2CH3) and butyl (-CH2CH2CH2CH3). 10Examples of alkyl groups include isopropyl (-CH(CH3)2), isobutyl (-CH2-CH(CH3)2), sec-butyl (-(CH3)CH-CH2CH3), tert-butyl (C(CH3)3), isopentyl ((CH2)2-CH(CH3)2), and tert-pentyl (-(CH3)2C-CH2-CH3). Alkenyl groups are aliphatic hydrocarbon groups having at least one carbon-carbon double bond (C=C) and are formed when a hydrogen atom is removed from an alkenyl group. Examples of alkenyl groups include vinyl (-CH=CH2), allyl (-CH2-HC=CH2), propenyl (-CH=CHCH3), isopropenyl (-(CH3)C=CH2), ethylene (=CH-CH3), isopropylene (=C(CH3)2). Examples of aryl groups include phenyl (-C6H5), benzyl (-CH2-C6H5), benzylidene (=CHC6H5), styryl (CH=CHC6H5), phenethyl (-CH2-CH2-C6H5), cinnamyl (-CH2CH=CHC6H5), benzhydryl (-CH(C6H5)2). In some aspects, X 1 , X 2 , X 3 , X 4 , X 5 and X 6 Each may independently be a trifluoromethyl group (-CF3).

[0105] R 1 , R 2 , R 3 , R 4 , R 5 and R 6 Each of them can be independently a fluorinated or non-fluorinated C1-C3 straight chain divalent hydrocarbon group. 1 , R 2 , R 3 , R 4 , R 5 and R 6 R may be independently fluorinated or non-fluorinated methylene (—CH2—), ethylene (—CH2—CH2—), trimethylene (—CH2—CH2—CH2—), vinylene (—HC═CH—), propenylene (—H2C═C═CH—), or propylene (—CH(CH3)CH2). In some aspects, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 They may each independently be a methylene group.

[0106] Examples of fluorinated triesters of formula (1) include tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate (CAS No. 66489-68-7) (THFPP), tris(1,1,1,5,5,5-hexafluoropentan-3-yl) phosphate (PubChem CID 87107505), tris(1,1,1,2,3,3,3-heptafluoropropan-2-yl) phosphate (PubChem CID 87090955), and combinations thereof.

[0107] In some aspects, the fluorinated phosphate additive can be a compound comprising a cyclic phosphate group connected to a fluorocarbon group. For example, the fluorinated phosphate additive can be a fluorinated cyclic phosphate having the following formula (2):

[0108]

[0109] Where R 1 is a non-fluorinated divalent hydrocarbon group, R 2 is a fluorinated or non-fluorinated divalent hydrocarbon group, and X is a fluorocarbon group. 1 It can be methylene (—CH2—), ethylene (—CH2—CH2—), trimethylene (—CH2—CH2—CH2—), vinylene (—HC═CH—), propenylene (—H2C═C═CH—), or propylene (—CH(CH3)CH2). In some aspects, R 1 It can be ethylene. 2 It can be a fluorinated or non-fluorinated methylene (—CH2—), ethylene (—CH2CH2—), trimethylene (—CH2-CH2-CH2—), vinylene (—HC═CH—), propenylene (—H2C═C═CH—), or propylene (—CH(CH3)CH2—). In some aspects, R 2 X can be a polyfluorinated or perfluorinated C1-C 10 Straight or branched chain alkyl, alkenyl, alkynyl, aryl, or a combination thereof. In some aspects, X can be trifluoromethyl (-CF3).

[0110] An example of the fluorinated cyclic phosphate having the following formula (2) is 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide (CAS No. 67605-68-9) (TEDPO).

[0111] The fluorinated phosphate additive may comprise greater than or equal to about 0.1 wt %, optionally about 0.5 wt %, optionally about 1 wt % to less than or equal to about 5 wt %, optionally about 3 wt %, optionally about 2 wt %, or optionally about 1.5 wt % of the electrolyte 28. In some aspects, the fluorinated phosphate additive may comprise greater than or equal to about 1.5 wt % to less than or equal to about 2.5 wt % of the electrolyte 28.

[0112] During the initial charge and / or cycle of the battery 20, the first interface layer 38 and the second interface layer 42 may be inherently formed in situ on the surface 40 of the negative electrode 22 and the surface 44 of the positive electrode 24, respectively, due to, for example, chemical reactions between the fluorinated phosphate additive in the electrolyte 28 and the electroactive materials of the negative electrode 22 and the positive electrode 24. During the initial charge and / or cycle of the battery 20, the first interface layer 38 may be inherently formed in situ on the surface of the negative electrode 22 due to electrochemical reduction of the fluorinated phosphate additive in the electrolyte 28 on the surface 40 of the electroactive material of the negative electrode 22. The first interface layer 38 may include electrochemical decomposition products of the fluorinated phosphate additive. Without wishing to be bound by theory, it is believed that the fluorinated phosphate additive may act as a sacrificial component of the electrolyte 28, thereby preventing degradation of the electrolyte 28 during charging and cycling of the battery 20. For example, it is believed that due to the relatively low (more negative) energy of the lowest unoccupied molecular orbital (LUMO) of the fluorinated phosphate ester additive, the fluorinated phosphate ester additive rather than other components of the electrolyte 28 (e.g., organic solvent and / or lithium salt) can be preferentially reduced on the surface 40 of the negative electrode 22 during the initial charge and / or cycling of the battery 20. For example, the LUMO energy of the fluorinated phosphate ester additive can be less than (more negative than) -0.5 electron volts (eV), or optionally less than or equal to about -0.55 eV. In contrast, other components of the electrolyte 28 can have higher (less negative) LUMO energies, such as propylene carbonate = 0.63 eV, ethyl methyl carbonate = 1.04 eV, and PF6 - =0.12 eV. In addition, the LUMO energy of the fluorinated phosphate additive may be smaller (more negative) than the LUMO energy of the non-fluorinated phosphate, for example, triethyl phosphate (TEP) =0.86 eV.

[0113] During the initial charge and / or cycling of the battery 20, the second interface layer 42 may be inherently formed in situ on the surface 44 of the positive electrode 24 due to the electrochemical oxidation of the fluorinated phosphate additive in the electrolyte 28 on the surface 44 of the electroactive material of the positive electrode 24. The second interface layer 42 may include electrochemical decomposition products of the fluorinated phosphate additive. In particular, the second interface layer 42 may include reaction products of the electrochemical oxidation of the fluorinated phosphate additive.

[0114] The first interface layer 38 and the second interface layer 42 are electrically insulating and ionically conductive and are configured to help prevent undesirable chemical reactions from occurring between the electrolyte 28 and the respective negative and positive electrodes 22, 24 during cycling of the battery 20. For example, after the first interface layer 38 and the second interface layer 42 are formed on the surface 40 of the negative electrode 22 and the surface 44 of the positive electrode 24, respectively, the first interface layer 38 and the second interface layer 42 can help prevent chemical reactions from occurring between components of the electrolyte 28 and the negative and positive electrodes 22, 24 during charging and / or discharging of the battery 20. Without wishing to be bound by theory, it is believed that the formation of the first interface layer 38 and the second interface layer 42 can help prevent undesirable chemical reactions from occurring between the electrolyte 28 and the respective negative and positive electrodes 22, 24 without hindering the flow of lithium ions between the electrolyte 28 and the negative and positive electrodes 22, 24.

[0115] exist Figure 3 , the first interface layer 38 is depicted as being disposed along the interface between the negative electrode 22 and the separator 26, and the second interface layer 42 is depicted as being disposed along the interface between the positive electrode 24 and the separator 26; however, other arrangements are possible. For example, in aspects where the electroactive materials of the negative electrode 22 and the positive electrode 24 are in the form of granular materials, the first interface layer 38 may extend at least partially into the negative electrode 22 (toward the negative electrode current collector 30) and may be disposed on the surface of one or more electroactive material particles of the negative electrode 22. Similarly, in some aspects, the second interface layer 42 may extend at least partially into the positive electrode 24 (toward the positive electrode current collector 32) and may be disposed on the surface of one or more electroactive material particles of the positive electrode 24.

[0116] The positive electrode current collector 30 and the negative electrode current collector 32 are conductive and provide electrical connections between the external circuit 36 ​​and their respective positive electrode 22 and negative electrode 24. In some aspects, the positive electrode current collector 30 and the negative electrode current collector 32 can be in the form of a non-porous metal foil, a perforated metal foil, a porous metal mesh, or a combination thereof. The negative electrode current collector 30 can be made of copper, nickel, or alloys thereof, stainless steel, or other suitable conductive materials. The positive electrode current collector 32 can be made of aluminum (Al) or another suitable conductive material.

[0117] experiment

[0118] Whole button cells containing different electrolyte formulations were assembled and evaluated using a constant current charge and discharge protocol. All cells included a negative electrode consisting of an electroactive material consisting of a mixture of graphite and silicon oxide, conductive particles, and a polymer binder. Some cells included a positive electrode consisting of an electroactive material consisting of an overlithiated nickel manganese oxide (Ni:Mn ratio = 3:7, 0% Co, NCM 307), conductive particles, and a polymer binder, while other cells included a positive electrode consisting of an electroactive material consisting of nickel cobalt manganese aluminum oxide (NCMA), conductive particles, and a polymer binder.

[0119] A first comparative electrolyte (CON1) was prepared consisting of: 1.2 moles of LiPF6 in a mixture of FEC-DEC (FEC:DEC=1:4 vol / vol). Electrolytes according to embodiments of the present disclosure were prepared by adding tris(1,1,1,3,3,3-hexafluoroprop-2-yl) phosphate (1 wt%, 2 wt%, or 3 wt% THFPP) (THFPP-CON1) or 1 wt% 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide (1 wt% TEDPO) (TEDPO-CON1) to the first comparative electrolyte.

[0120] A second comparative electrolyte (CON2) was prepared consisting of 1 mole of LiPF6, 2 wt% FEC, and 1 wt% VC in a mixture of EC and DMC (EC:DMC=3:7 vol / vol). An electrolyte according to an embodiment of the present disclosure was prepared by adding 2 wt% tris(1,1,1,3,3,3-hexafluoropropane-2-yl) phosphate (2 wt% THFPP) and 1 wt% LiDFOB (THFPP-LiDFOB-CON2) to the second comparative electrolyte.

[0121] During formation, the cell was charged to a potential of about 4.5 V and then discharged to 2.0 V. In subsequent cycles, the cell was cycled between 2.0 V and 4.4 V.

[0122] The cells including NCM 307 positive electrode and 1 wt % TEDPO-CON1 electrolyte have high areal capacity and higher normalized capacity retention than those including NCM 307 positive electrode and CON1 electrolyte, indicating that the addition of TEDPO to FEC-DEC-containing electrolyte can improve the electrochemical performance of batteries including lithium-rich manganese transition metal oxides as positive electrode materials.

[0123] The cells including NCMA positive electrode and 2 wt% THFPP-1 wt% LiDFOB-CON2 electrolyte have high areal capacity and higher normalized capacity retention than those including CON2 electrolyte, indicating that the addition of THFPP in combination with LiDFOB to the electrolyte containing EC, DMC, FEC, and VC can improve the electrochemical performance of battery packs including lithium-rich nickel transition metal oxides as positive electrode materials.

[0124] The cell including the NCM 307 positive electrode and the 2 wt % THFPP-CON1 electrolyte has a high areal capacity and a higher normalized capacity retention than the cells including the 1 wt % THFPP-CON1 electrolyte and the 3 wt % THFPP-CON1 electrolyte, indicating that unexpectedly good results can be obtained by adding 2 wt % THFPP (instead of 1 wt % THFPP or 3 wt % THFPP) to the FEC-DEC-containing electrolyte of the battery pack including the lithium manganese-rich transition metal oxide as the positive electrode material.

[0125] The cells including NCM 307 positive electrode and 1 wt % THFPP-1 wt % LiPO2F2-CON1 electrolyte have high areal capacity and higher normalized capacity retention than the cells including 2 wt % THFPP-1 wt % LiPO2F2-CON1 electrolyte and CON1 electrolyte, indicating that unexpectedly good results can be obtained by adding about 1 wt % THFPP (rather than 2 wt % THFPP) when THFPP and LiPO2F2 are added to the FEC-DEC-containing electrolyte of a battery including lithium-rich manganese transition metal oxides as positive electrode materials.

[0126] The foregoing description is essentially only exemplary and is absolutely not intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be limited thereto, because after studying the drawings, the specification and the following claims, other modifications will become apparent. It should be understood that one or more steps in the method may be implemented in different orders (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more features described with respect to any embodiment of the present disclosure may be implemented in any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and the mutual replacement of one or more embodiments is still within the scope of the present disclosure.

[0127] The terms used herein are intended to be limited only for the purpose of describing exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one" and "the" used herein are intended to also include plural forms. The terms "comprising", "including" and "having" are inclusive, and therefore specify the presence of specified features, elements, compositions, steps, integers, operations and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their combinations. Although the open terms "comprising", "including" and "having" should be understood as non-limiting terms for describing and requesting the various embodiments described herein, in some aspects, these terms are understood as more restrictive and constraining terms, such as "consisting of..." or "consisting essentially of..." Therefore, for any given embodiment of a composition, material, component, element, ingredient, feature, integer, operation and / or method step, the present disclosure also clearly includes an embodiment consisting of or essentially consisting of these enumerated compositions, materials, components, elements, ingredients, features, integers, operations and / or method steps. In the case of “consisting of,” the alternative embodiment does not include any additional compositions, materials, components, elements, ingredients, features, integers, operations and / or method steps, while in the case of “consisting essentially of,” such an embodiment does not include any additional compositions, materials, components, elements, ingredients, features, integers, operations and / or method steps that substantially affect the basic and novel characteristics, but may include any compositions, materials, components, elements, ingredients, features, integers, operations and / or method steps that do not substantially affect the basic and novel characteristics in the embodiment.

[0128] Any method steps, methods, and operations described herein are not to be construed as necessarily requiring their performance in the order discussed or illustrated, unless expressly specified as an order of performance. It is also to be understood that additional or alternative steps may be used unless otherwise specified.

[0129] When a component, element, or layer is referred to as being "on," "engaged," "connected," or "coupled" to another element or layer, it may be directly on, directly engaged, connected, or coupled to, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). The term "and / or" as used herein includes a combination of one or more related enumerated items.

[0130] Unless otherwise indicated, although the term first, second, third etc. can be used to describe various steps, elements, components, regions, layers and / or parts in this article, these steps, elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish a step, element, component, region, layer or part from another step, element, component, region, layer or part. Unless the context clearly indicates, when using terms such as "first", "second" and other numerical terms in this article, order or sequence are not implied. Therefore, without departing from the teaching of the exemplary embodiment, the first step, element, component, region, layer or part discussed below can be referred to as the second step, element, component, region, layer or part.

[0131] For ease of description, spatially relative terms such as "before", "after", "inside", "outside", "below", "below", "lower", "above", "upper", etc. may be used herein to describe the relationship of one element or feature to another element or feature, as shown in the figures. The spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0132] Throughout this disclosure, numerical values ​​represent approximate measurements or limits to ranges, and encompass minor deviations from given values ​​and embodiments, with approximately the values ​​mentioned and with the exact values ​​mentioned. In addition to the working examples provided at the end of the specific embodiments, the numerical values ​​of the parameters (e.g., quantities or conditions) in this specification should be understood in all cases as being modified by the term "about" in each corresponding instance, regardless of whether "about" actually appears before the numerical value. "About" means that the specified numerical value allows some slight imprecision (making the value accurate by some method; approximately or quite close to the value; almost). If the imprecision provided by "about" is not understood in the art with this common meaning, the "about" used herein at least indicates the changes that may be produced by the common methods of measuring and using such parameters. For example, "about" can include changes that are less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some aspects, optionally less than or equal to 0.1%. Additionally, the disclosure of ranges includes disclosure of individual values ​​and further subdivided ranges within the entire range, including the endpoints and sub-ranges given for the ranges.

[0133] As used herein, the terms "composition" and "material" are used interchangeably to refer broadly to a substance containing at least a preferred chemical composition, element or compound, but unless otherwise indicated, it may also contain additional elements, compounds or substances, including trace amounts of impurities. An "X-based" composition or material broadly refers to a composition or material in which "X" is the single largest constituent of the composition or material based on a weight percentage (%). This can include compositions or materials having greater than 50 wt % X, as well as those having less than 50 wt % X, as long as X is the single largest constituent of the composition or material based on its total weight. When a composition or material is referred to as being "substantially free" of a substance, the composition or material may contain less than 5 wt %, optionally less than 3 wt %, optionally less than 1 wt %, or optionally less than 0.1 wt % of the substance.

[0134] As used herein, the term "metal" may refer to a pure elemental metal or an alloy of an elemental metal with one or more other metals or nonmetallic elements, referred to as "alloying" elements. Alloying elements may be selected to impart certain desirable properties to the alloy that are not exhibited by the base metal element.

Claims

1. A battery pack for circulating lithium ions, the battery pack comprising: a positive electrode comprising an electroactive material comprising a layered lithium transition metal oxide; a negative electrode comprising an electroactive material comprising silicon oxide, lithiated silicon oxide, graphite, or a combination thereof; and An electrolyte infiltrated into the positive electrode and the negative electrode, the electrolyte comprising: Organic solvents; a lithium salt in the organic solvent; and A fluorinated phosphate additive in the organic solvent, the fluorinated phosphate additive comprising at least one of the following: (i) a compound comprising a phosphate group attached to two or three branched fluorocarbon groups, or (ii) Compounds containing a cyclic phosphate group linked to a fluorocarbon group The fluorinated phosphate additive comprises greater than or equal to about 0.5 wt % to less than or equal to about 2.5 wt % of the electrolyte.

2. The battery of claim 1, wherein the fluorinated phosphate ester additive comprises a fluorinated phosphate triester having formula (1): Where X 1 , X 2 , X 3 , X 4 , X 5 and X 6 are each independently a fluorocarbon group, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently a fluorinated or non-fluorinated divalent hydrocarbon group, and Y 1 , Y 2 and Y 3 are each independently hydrogen (H) or fluorine (F).

3. The battery of claim 2, wherein the fluorinated phosphate additive comprises tris(1,1,1,3,3,3-hexafluoropropan-2-yl) phosphate, tris(1,1,1,5,5,5-hexafluoropentan-3-yl) phosphate, tris(1,1,1,2,3,3,3-heptafluoropropane-2-yl) phosphate, or a combination thereof.

4. The battery of claim 1, wherein the fluorinated phosphate additive comprises a fluorinated cyclic phosphate having formula (2): Where R 1 is a non-fluorinated divalent hydrocarbon group, R 2 is a fluorinated or non-fluorinated divalent hydrocarbon group, and X is a fluorocarbon group. 5 . The battery of claim 4 , wherein the fluorinated phosphate additive comprises 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide.

6. The battery pack according to claim 1, wherein the electroactive material of the positive electrode comprises a layered lithium-rich manganese transition metal oxide, the organic solvent comprises a mixture of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC), and the lithium salt comprises lithium hexafluorophosphate (LiPF6).

7. The battery of claim 6, wherein the electrolyte further comprises lithium difluorophosphate (LiPO2F2), and wherein the fluorinated phosphate additive comprises greater than or equal to about 0.5 wt% to less than or equal to about 1.5 wt% of the electrolyte, and LiPO2F2 comprises greater than or equal to about 0.5 wt% to less than or equal to about 1.5 wt% of the electrolyte.

8. The battery of claim 1, wherein the electroactive material of the positive electrode comprises a layered lithium-rich manganese transition metal oxide, and wherein the organic solvent comprises a mixture of fluoroethylene carbonate (FEC) and diethyl carbonate (DEC).

9. The battery according to claim 8, wherein the lithium salt comprises lithium hexafluorophosphate (LiPF6) and lithium difluoro(oxalato)borate (LiDFOB), and wherein the electrolyte further comprises fluoroethylene carbonate (FEC) and vinylene carbonate (VC).

10. The battery of claim 9, wherein the fluorinated phosphate additive comprises greater than or equal to about 1.5 wt % to less than or equal to about 2.5 wt % of the electrolyte, LiDFOB comprises greater than or equal to about 0.5 wt % to less than or equal to about 1.5 wt % of the electrolyte, FEC comprises greater than or equal to about 1.5 wt % to less than or equal to about 2.5 wt % of the electrolyte, and VC comprises greater than or equal to about 0.5 wt % to less than or equal to about 1.5 wt % of the electrolyte.

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