Electrolyte additive for forming solid electrolyte interface on polytetrafluoroethylene-containing negative electrode and battery comprising same

Abstract

A lithium ion circulating battery includes a negative electrode and an ion conductive electrolyte. The negative electrode includes electroactive negative electrode particles embedded in a polytetrafluoroethylene matrix. The electrolyte includes an organic solvent, an inorganic lithium salt, and a functional additive including a chemical compound including a bis (trifluoromethanesulfonimide) group and a substituted phenyl group.

Description

Technical Field

[0001] The present disclosure relates to electrolyte additives for cycling lithium-ion batteries, and more particularly, to electrolyte additives formulated to form a solid electrolyte interface on a negative electrode during initial charging of the battery. 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] The present disclosure relates to electrolyte additives for cycling lithium-ion batteries, and more particularly, to electrolyte additives formulated to form a solid electrolyte interface on a negative electrode during initial charging of the battery.

[0004] Lithium batteries are widely used in various electronic devices and are promising candidates for meeting the requirements of electric vehicles, including hybrid electric vehicles, due to their high energy and power density. Secondary lithium batteries typically include a negative electrode, a positive electrode and an electrolyte, which provides a medium for the conduction of lithium ions between the negative electrode and the positive electrode during the charge and discharge process of the battery. During the manufacturing process, the electrodes are usually deposited in the form of a thin layer on a conductive metal current collector. The negative electrode layer and the positive electrode layer may have a composite structure, including electrochemically active particles embedded in a polymer binder. An example of a polymer binder that can be beneficially used to make a composite electrode by a dry process is polytetrafluoroethylene. Summary of the invention

[0005] A battery pack for circulating lithium ions is disclosed. The battery pack includes a positive electrode, a negative electrode spaced apart from the positive electrode, and an electrolyte that provides an ion conduction path for lithium ions to be transported between the positive electrode and the negative electrode. The negative electrode includes a particulate component embedded in a polymer matrix component. The particulate component includes electroactive negative electrode particles and the polymer matrix component includes polytetrafluoroethylene. The electrolyte includes an organic solvent, an inorganic lithium salt, and a functional additive, the functional additive including a chemical compound containing a bis(trifluoromethanesulfonylimide) group and a substituted phenyl group.

[0006] The functional additive may include a chemical compound having the following formula (1):

[0007]

[0008] Where R 1 , R 2 and R 3 Each is independently hydrogen, alkyl, alkene or halogen.

[0009] During the initial charging process of the battery, the functional additive can decompose and form a solid electrolyte interface on the surface of the electroactive negative electrode particles to isolate the electroactive negative electrode particles from physical contact with the polymer matrix component. In addition, during the subsequent cycling of the battery, the solid electrolyte interface can prevent chemical reactions between the electroactive negative electrode particles and the polytetrafluoroethylene in the polymer matrix component.

[0010] During the initial charging of the battery pack, when the negative electrode is relatively close to Li / Li + At a potential of greater than or equal to about 1.5 volts and less than or equal to about 2.2 volts, the functional additive may decompose and form a solid electrolyte interface on the surface of the electroactive negative electrode particles.

[0011] The electroactive negative electrode particles may have a solid electrolyte interface formed on a surface thereof. The solid electrolyte interface may include one or more chemical compounds including a bis(trifluoromethanesulfonylimide) group, a trifluoromethyl group, a sulfur oxide group, or a combination thereof.

[0012] The functional additive may comprise greater than or equal to about 0.1% to less than or equal to about 5% by weight of the electrolyte.

[0013] The inorganic lithium salt may include lithium hexafluorophosphate.

[0014] The organic solvent may include a mixture of ethylene carbonate and ethyl methyl carbonate.

[0015] The polymer matrix component may include greater than or equal to about 90 weight percent polytetrafluoroethylene.The polymer matrix component may comprise greater than or equal to about 1 weight percent to less than or equal to about 5 weight percent of the negative electrode.

[0016] The electroactive negative electrode particles may comprise graphite, silicon, or a combination thereof.

[0017] The particulate component may also include an electrically conductive carbon-based material.

[0018] The polymer matrix component may be substantially free of polyvinylidene fluoride.

[0019] A battery pack for circulating lithium ions is disclosed. The battery pack includes a positive electrode, a negative electrode spaced apart from the positive electrode, and an electrolyte that provides an ion conduction path for lithium ions to be transported between the positive electrode and the negative electrode. The negative electrode includes electroactive negative electrode particles embedded in a polymer matrix component. The electroactive negative electrode particles include graphite particles, silicon particles, or a combination thereof. The polymer matrix component includes polytetrafluoroethylene. The electrolyte includes an organic solvent, an inorganic lithium salt, and a functional additive including a chemical compound having the following formula (1):

[0020]

[0021] Where R 1 , R 2 and R 3 Each is independently hydrogen, alkyl, alkene or halogen.

[0022] During initial charging of the battery, the functional additives may decompose and form a solid electrolyte interface on the surface of the electroactive negative electrode particles to isolate the electroactive negative electrode particles from physical contact with the polymer matrix components.

[0023] During the initial charging of the battery pack, when the negative electrode is relatively close to Li / Li + At a potential of greater than or equal to about 1.5 volts and less than or equal to about 2.2 volts, the functional additive may decompose and form a solid electrolyte interface on the surface of the electroactive negative electrode particles.

[0024] The electroactive negative electrode particles may have a solid electrolyte interface formed on a surface thereof. The solid electrolyte interface may include one or more chemical compounds including a bis(trifluoromethanesulfonylimide) group, a trifluoromethyl group, a sulfur oxide group, or a combination thereof.

[0025] The functional additive may comprise greater than or equal to about 0.1 wt % to less than or equal to about 5 wt % of the electrolyte.

[0026] The inorganic lithium salt may include lithium hexafluorophosphate.

[0027] The organic solvent may include a mixture of ethylene carbonate and ethyl methyl carbonate.

[0028] The polymer matrix component may include greater than or equal to about 90 weight percent polytetrafluoroethylene.The polymer matrix component may comprise greater than or equal to about 1 weight percent to less than or equal to about 5 weight percent of the negative electrode.

[0029] A method for making a battery pack is disclosed. The battery pack includes a negative electrode and an electrolyte impregnated with the negative electrode. The negative electrode includes graphite particles embedded in a polytetrafluoroethylene binder. The electrolyte includes a chemical compound containing a bis(trifluoromethanesulfonimide) group and a substituted phenyl group. A constant current is applied to the battery pack at a charge rate of less than or equal to about C / 20 until the battery pack reaches a predetermined maximum potential. Then, a constant voltage is applied to the battery pack at the predetermined maximum potential until the measured current reaches a charge rate of less than or equal to about C / 50.

[0030] 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

[0031] The present disclosure will be more fully understood through the detailed description and accompanying drawings, in which:

[0032] Figure 1 is a schematic perspective view of a motor vehicle powered by a battery pack including a plurality of battery modules.

[0033] Figure 2 yes Figure 1 Schematic cross-sectional view of a portion of one of the battery modules of FIG. 1 , the battery module comprising a plurality of battery cells arranged in a stack.

[0034] Figure 3 is a schematic cross-sectional view of a cycling lithium ion battery including a negative electrode comprising electroactive negative electrode particles and a polytetrafluoroethylene binder, and an electrolyte comprising a functional additive that forms a solid electrolyte interface on the electroactive negative electrode particles during initial charging of the battery.

[0035] Figure 4 yes Figure 3 Schematic cross-sectional view of one of the electroactive negative electrode particles including a solid electrolyte interphase formed on an outer surface thereof.

[0036] Figure 5 and Figure 6 is the measured current (mA) versus applied potential (V vs. Li / Li) for the first cycle of a half-coin cell including the baseline electrolyte (dashed line) and a half-coin cell including the electrolyte containing PhTFSI as a functional additive (solid line). + )'s cyclic voltammogram.

[0037] Figure 7 is the potential (V relative to Li / Li + ) versus capacity (mAh) plots depicting the charge and discharge curves of the first cycle for a half-coin cell including a baseline electrolyte (dashed line) and a half-coin cell including an electrolyte containing PhTFSI as a functional additive (solid line).

[0038] Figure 8 is the potential (V relative to Li / Li + ) versus capacity (mAh) plots depicting the charge and discharge curves of the first cycle for a full cell including a baseline electrolyte (dashed line) and a full cell including an electrolyte containing PhTFSI as a functional additive (solid line).

[0039] The present invention discloses the following scheme:

[0040] Solution 1. A circulating lithium ion battery pack, the battery pack comprising:

[0041] Positive electrode;

[0042] a negative electrode spaced apart from the positive electrode, the negative electrode comprising a particulate component embedded in a polymer matrix component, the particulate component comprising electroactive negative electrode particles and the polymer matrix component comprising polytetrafluoroethylene; and

[0043] An electrolyte that provides an ion-conducting path for the transfer of lithium ions between the positive electrode and the negative electrode, the electrolyte comprising:

[0044] Organic solvents;

[0045] Inorganic lithium salts; and

[0046] Functional additives include chemical compounds containing bis(trifluoromethanesulfonylimide) groups and substituted phenyl groups.

[0047] Option 2. The battery pack according to Option 1, wherein the functional additive comprises a chemical compound having the following formula (1):

[0048]

[0049] Where R 1 , R 2 and R 3 Each is independently hydrogen, alkyl, alkene or halogen.

[0050] Option 3. A battery pack according to Option 1, wherein during the initial charging process of the battery pack, the functional additive decomposes and forms a solid electrolyte interface on the surface of the electroactive negative electrode particles to isolate the electroactive negative electrode particles from physical contact with the polymer matrix component, and wherein, during subsequent cycling of the battery pack, the solid electrolyte interface prevents chemical reactions between the electroactive negative electrode particles and the polytetrafluoroethylene in the polymer matrix component.

[0051] Option 4. A battery pack according to Option 3, wherein during the initial charging process of the battery pack, when the negative electrode is relatively Li / Li + At a potential of greater than or equal to about 1.5 volts and less than or equal to about 2.2 volts, the functional additive decomposes and forms the solid electrolyte interface on the surface of the electroactive negative electrode particles.

[0052] Option 5. A battery pack according to Option 1, wherein the electroactive negative electrode particles have a solid electrolyte interface formed on the surface thereof, and wherein the solid electrolyte interface comprises one or more chemical compounds containing a bis(trifluoromethanesulfonylimide) group, a trifluoromethyl group, a sulfur oxide group, or a combination thereof.

[0053] Embodiment 6. The battery pack according to Embodiment 1, wherein the functional additive accounts for greater than or equal to about 0.1 wt % to less than or equal to about 5 wt % of the electrolyte.

[0054] Option 7. The battery pack according to Option 1, wherein the inorganic lithium salt comprises lithium hexafluorophosphate.

[0055] Embodiment 8. The battery pack according to Embodiment 1, wherein the organic solvent comprises a mixture of ethylene carbonate and ethyl methyl carbonate.

[0056] Option 9. A battery pack according to Option 1, wherein the polymer matrix component contains greater than or equal to about 90 weight percent polytetrafluoroethylene, and wherein the polymer matrix component accounts for greater than or equal to about 1 weight percent to less than or equal to about 5 weight percent of the negative electrode.

[0057] Embodiment 10. The battery pack of Embodiment 1, wherein the electroactive negative electrode particles comprise graphite, silicon, or a combination thereof.

[0058] Option 11. A battery pack according to Option 1, wherein the particulate component also includes a conductive carbon-based material.

[0059] Embodiment 12. The battery pack according to Embodiment 1, wherein the polymer matrix component is substantially free of polyvinylidene fluoride.

[0060] Solution 13. A circulating lithium ion battery pack, the battery pack comprising:

[0061] Positive electrode;

[0062] a negative electrode spaced apart from the positive electrode, the negative electrode comprising electroactive negative electrode particles embedded in a polymer matrix component, the electroactive negative electrode particles comprising graphite particles, silicon particles, or a combination thereof, and the polymer matrix component comprising polytetrafluoroethylene; and

[0063] An electrolyte that provides an ion-conducting path for the transfer of lithium ions between the positive electrode and the negative electrode, the electrolyte comprising:

[0064] Organic solvents;

[0065] Inorganic lithium salts; and

[0066] A functional additive comprising a chemical compound having the following formula (1):

[0067]

[0068] Where R 1 , R 2 and R 3 are each independently hydrogen, alkyl, alkene or halogen,

[0069] wherein during an initial charge of the battery, the functional additive decomposes and forms a solid electrolyte interface on the surface of the electroactive negative electrode particles to isolate the electroactive negative electrode particles from physical contact with the polymer matrix component.

[0070] Solution 14. A battery pack according to Solution 13, wherein during the initial charging process of the battery pack, when the negative electrode is relatively + At a potential of greater than or equal to about 1.5 volts and less than or equal to about 2.2 volts, the functional additive decomposes and forms the solid electrolyte interface on the surface of the electroactive negative electrode particles.

[0071] Option 15. A battery pack according to Option 13, wherein the electroactive negative electrode particles have a solid electrolyte interface formed on the surface thereof, and wherein the solid electrolyte interface comprises one or more chemical compounds containing a bis(trifluoromethanesulfonylimide) group, a trifluoromethyl group, a sulfur oxide group, or a combination thereof.

[0072] Embodiment 16. The battery pack according to Embodiment 13, wherein the functional additive accounts for greater than or equal to about 0.1 wt % to less than or equal to about 5 wt % of the electrolyte.

[0073] Embodiment 17. A battery pack according to Embodiment 13, wherein the inorganic lithium salt comprises lithium hexafluorophosphate.

[0074] Embodiment 18. The battery pack according to Embodiment 13, wherein the organic solvent comprises a mixture of ethylene carbonate and ethyl methyl carbonate.

[0075] Option 19. A battery pack according to Option 13, wherein the polymer matrix component comprises greater than or equal to about 90 weight percent polytetrafluoroethylene, and wherein the polymer matrix component accounts for greater than or equal to about 1 weight percent to less than or equal to about 5 weight percent of the negative electrode.

[0076] 20. A method for manufacturing a battery, the battery comprising a negative electrode and an electrolyte impregnated with the negative electrode, the negative electrode comprising graphite particles embedded in a polytetrafluoroethylene binder, and the electrolyte comprising a chemical compound containing a bis(trifluoromethanesulfonylimide) group and a substituted phenyl group, the method comprising:

[0077] applying a constant current to the battery pack at a charge rate less than or equal to about C / 20 until the battery pack reaches a predetermined maximum potential; and then

[0078] A constant voltage is applied to the battery pack at the predetermined maximum potential until a measured current reaches a charge rate less than or equal to about C / 50.

[0079] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0080] The electrolyte disclosed herein can be used in batteries of cycling lithium ions to help improve their coulombic efficiency, for example, by preventing undesirable side reactions between electroactive negative electrode particles and polytetrafluoroethylene binders in the negative electrode of the battery. Specifically, the electrolyte disclosed herein comprises a functional additive that is formulated to form a solid electrolyte interface on the surface of the electroactive negative electrode particles during the initial charging process of the battery to physically isolate the electroactive negative electrode particles from the polytetrafluoroethylene binder and thereby prevent physical and chemical interactions between the electroactive negative electrode particles in the negative electrode and the polytetrafluoroethylene binder.

[0081] Figure 1 A motor vehicle 2 is depicted that is powered by an electric motor 4 that draws power from a battery pack 6 that includes one or more battery modules 8. The battery modules 8 may be electrically coupled 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 the electric motor 4 and by an internal combustion engine (not shown).

[0082] like Figure 2 As 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 generally assembled into stacked layers, including a negative electrode layer 12, a negative electrode collector 13, a positive electrode layer 14, a positive electrode 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 the negative electrode collector 13 and is in electrical communication with the negative electrode collector 13, and the positive electrode layer 14 is disposed on the positive electrode collector 15 and is in electrical communication with the positive electrode collector 15. As shown in FIG. Figure 2 As shown in , for efficiency, the layers can be stacked so that some negative electrode collectors 13 and positive electrode collectors 15 are double-sided and include negative electrode layers 12 or positive electrode layers 14 on both sides thereof. In this arrangement, adjacent negative electrode layers 12 and positive electrode layers 14 share a single negative electrode collector 13 or positive electrode collector 15.

[0083] Figure 3An electrochemical cell or battery 20 of circulating lithium ions is depicted. The battery 20 can generate an electric current during discharge, which can be used to power a load device (e.g., a motor 4), and can be recharged by connecting to a power source. Figure 1 and Figure 2 1 , in various 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 fixed and / or portable electronic devices, components, and devices used in a variety of other industries and applications, including industry, residential and commercial construction, consumer products, industrial equipment and machinery, agricultural or farm equipment, and heavy machinery, as non-limiting examples.

[0084] The battery 20 includes a negative electrode 22, a positive electrode 24, a separator 26, and an electrolyte 28 that impregnates 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 coupled to a power source or load 34 (e.g., the motor 12) through an external circuit 36. The negative electrode 22 and the positive electrode 24 are configured so that when the battery 20 is at least partially charged, an electrochemical potential difference is established between the negative electrode 22 and the positive electrode 24. During the discharge process 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 releases 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 through 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-spontaneous redox reaction within the battery 20 and releases lithium ions and electrons from the positive electrode 24. Repeated discharge and charging 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 one complete cycle.

[0085] The negative electrode 22 is a porous composite material and includes a polymer matrix component 38 and a particulate component embedded in the polymer matrix component 38. The particulate component includes electrochemically active (electroactive) particles 40 and optional conductive particles 42 distributed throughout the polymer matrix component 38. The polymer matrix component 38 and the particulate component of the negative electrode 22 can define a plurality of open pores and can provide the negative electrode 22 with a porosity of greater than or equal to about 20% to less than or equal to about 50%. The negative electrode 22 can have a porosity of greater than or equal to about 1.3 grams per cubic centimeter (g / cm3 ) to less than or equal to about 2 g / cm 3 density.

[0086] The polymer matrix component 38 is formulated to act as a binder and provide structural integrity to the negative electrode 22, for example, by creating cohesive forces between the electroactive particles 40 and the optional conductive particles 42. The polymer matrix component 38 includes polytetrafluoroethylene (PTFE). The polymer matrix component 38 may contain greater than about 80% by weight, greater than about 90% by weight, greater than about 95% by weight, or greater than about 99% by weight of polytetrafluoroethylene. In various aspects, the polymer matrix component 38 may be substantially composed of or entirely composed of polytetrafluoroethylene. The polymer matrix component 38 may account for greater than or equal to about 0.5% by weight of the negative electrode 22, or optionally about 1% by weight, to less than or equal to about 10% by weight, optionally about 5% by weight, or optionally about 3% by weight. In various aspects, the polymer matrix component 38 may account for about 1.5% by weight of the negative electrode 22.

[0087] The electroactive particles 40 can store and release lithium ions during charging and discharging of the battery pack 20, respectively. The electroactive particles 40 include one or more electrochemically active (electroactive) materials that can undergo reversible redox reactions with lithium during charging and discharging of the battery pack 20. For example, the electroactive particles 40 can include a lithium intercalation host material, a material that can reversibly alloy with lithium (lithium alloying material), and / or a conversion material that can reversibly react with lithium by undergoing a phase change or a change in crystal structure accompanied by a change in oxidation state during charging and discharging of the battery pack 20. Examples of the lithium intercalation host material, the lithium alloying material, and the conversion material include: carbon-based materials (e.g., graphite, graphene, and / or carbon nanotubes), silicon-based materials (e.g., silicon (Si), Si alloys, and / or silicon oxide (SiOx, where 0 < x < 2), lithiated silicon oxide (LiySiOx, where 0 < x < 2, 0 < y < 1)), tin-based materials (e.g., tin (Sn) and / or Sn alloys), metal oxides (e.g., V2O5 and / or Co3O4), and / or metal sulfides (e.g., FeS). In various aspects, the electroactive particles 40 can include a combination of a carbon-based material and a silicon-based material. For example, the electroactive particles 40 can include a combination of graphite and silicon. In various aspects, the electroactive particles 40 can comprise greater than or equal to about 50 wt%, greater than or equal to about 75 wt%, or greater than or equal to about 90 wt% of a carbon-based material (e.g., graphite). In various aspects, the electroactive particles 40 can comprise greater than or equal to about 1 wt% to less than or equal to about 50 wt%, or optionally about 15 wt% of silicon. The electroactive particles 40 can account for greater than or equal to about 90 wt%, or optionally about 95 wt%, to less than or equal to about 99 wt%, or optionally about 98 wt% of the negative electrode 22. The electroactive particles 40 can provide the negative electrode 22 with an areal capacity of greater than or equal to about 3.5 milliamperes-hour per square centimeter (mAh / cm 2 ) to less than or equal to about 7.5 mAh / cm 2 .

[0088] As Figure 3 and Figure 4 shown, after initial charging of the battery pack 20 and / or after formation cycling of the battery pack 20, the electroactive particles 40 include a solid electrolyte interface 44 formed in-situ on its surface 46. The solid electrolyte interface 44 is ion-conductive and electrically insulating and allows lithium ions to pass therethrough during charging and discharging of the battery pack 20. In various aspects, the solid electrolyte interface 44 can be formed on substantially the entire outer surface of each electroactive particle 40. In such a case, each electroactive particle 40 can be completely encapsulated by the solid electrolyte interface 44.

[0089] The optional conductive particles 42 are formulated to provide the negative electrode 22 with high conductivity, for example, by forming a strong conductive network throughout the negative electrode 22. The conductive particles 42 are electrochemically inert and do not reversibly react with lithium during the charge and discharge process of the battery 20. The conductive particles 42 may include particles of carbon-based materials, metal particles, and / or conductive polymers. Examples of conductive carbon-based materials include carbon black (e.g., acetylene black), graphite, graphene (e.g., graphene nanosheets), carbon nanotubes (e.g., single-walled and / or multi-walled carbon nanotubes), carbon fibers (e.g., carbon nanofibers), and / or Examples of conductive metal particles include powdered copper, nickel, aluminum, silver, and / or alloys thereof. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, and / or polypyrrole. Optional conductive particles 42 may account for more than 0% by weight of the negative electrode 22, or optionally from about 0.5% by weight to less than or equal to about 5% by weight, or optionally about 1% by weight. For example, conductive particles 42 may account for about 0.8% by weight of the negative electrode 22.

[0090] The positive electrode 24 can store and release lithium ions during the discharge and charge process of the battery pack 20. The positive electrode 24 includes an electroactive material that can undergo a reversible redox reaction with lithium at a higher electrochemical potential than the electroactive particles 40 of the negative electrode 22, so that an electrochemical potential difference exists between the negative electrode 22 and the positive electrode 24. For example, the positive electrode 24 may include an electroactive material that is capable of sufficient lithium insertion and deinsertion, alloying and dealloying, or plating and stripping. In one form, the electroactive material of the positive electrode 24 may include an intercalation host material that can undergo reversible insertion or insertion of lithium ions. In this case, the electroactive material of the positive electrode 24 may include a lithium transition metal oxide. For example, the electroactive material of the positive electrode 24 may include a layered oxide represented by the formula LiMeO2, an olivine-type oxide represented by the formula LiMePO4, a spinel-type oxide represented by the formula LiMe2O4, and a tavorite 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). In some embodiments, the electroactive material of the positive electrode 24 may include a material selected from lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese aluminum oxide (NCMA) and lithium manganese iron phosphate (LMFP). In another form, the electroactive material of the positive electrode 24 may include a conversion material including a component that can undergo a reversible electrochemical reaction with lithium, wherein the component undergoes a phase change or a crystal structure change accompanied by a change in oxidation state. In this case, the electroactive material of the positive electrode 24 may include sulfur, selenium, tellurium, iodine, halides (e.g., fluorides or chlorides), sulfides, selenides, tellurides, iodides, phosphides, nitrides, oxides, oxysulfides, oxyfluorides, sulfur fluorides, sulfur oxyfluorides, or lithium and / or metal compounds thereof. Examples of suitable metals included in the conversion material of the electroactive material of the positive electrode 24 include iron, manganese, nickel, copper, and cobalt.

[0091] The electroactive material of the positive electrode 24 can be mixed with a conductive agent and a polymer binder. The conductive agent can include any material discussed above with respect to the conductive particles 42. The polymer binder can include an organic polymer. Examples of organic polymers include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene propylene diene monomer (EPDM) rubber, styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC) and / or polyacrylic acid (PAA).

[0092] The separator 26 physically and electrically isolates 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 polymers, such as a laminate of PE and PP. In various aspects, the separator 26 may include a ceramic coating (not shown) disposed on one or both sides thereof. In this case, the ceramic coating may include particles of aluminum oxide (Al2O3) and / or silicon dioxide (SiO2).

[0093] The negative electrode current collector 30 and the positive electrode current collector 32 are conductive and provide electrical connections between the external circuit 36 ​​and their corresponding negative electrode 22 and positive electrode 24. In various aspects, the negative electrode current collector 30 and the positive 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 an alloy 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.

[0094] The electrolyte 28 is ionically conductive and provides a medium for lithium ions to be conducted between the negative electrode 22 and the positive electrode 24. In assembly, the battery 20 is impregnated with the electrolyte 28 so that the electrolyte 28 is in direct physical contact with the negative electrode 22, the positive electrode 24, and the separator 26. For example, the electrolyte 28 may infiltrate the open pores of the negative electrode 22, the positive electrode 24, and the separator 26. The electrolyte 28 is formulated to provide enhanced cycling stability for the battery 20 by promoting the in-situ formation of a solid electrolyte interface 44 on the surface 46 of the electroactive particles 40 of the negative electrode 22 during the initial charging process of the battery 20. The electrolyte 28 may include an organic solvent, optionally one or more co-solvents, a lithium salt, and a functional additive.

[0095] The organic solvent may include a non-aqueous aprotic organic solvent. For example, the organic solvent may include an alkyl carbonate, an aliphatic carboxylic acid ester, a γ-lactone, or a combination thereof. In various aspects, the organic solvent may include a mixture of an alkyl carbonate, such as a mixture of a cyclic carbonate and a linear carbonate. Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC) and combinations thereof. Examples of linear carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and combinations thereof. Examples of aliphatic carboxylic acid esters include methyl formate, methyl acetate, methyl propionate and combinations thereof. Examples of γ-lactones include γ-butyrolactone, γ-valerolactone and combinations thereof.

[0096] The organic solvent may account for greater than or equal to about 70% by weight to less than or equal to about 90% by weight of the electrolyte 28. The volume ratio of the cyclic carbonate to the linear carbonate in the organic solvent may be greater than or equal to about 2 to 8 (cyclic carbonate: linear carbonate = 2: 8) and less than or equal to about 4 to 6 (4: 6). In various aspects, the volume ratio of the cyclic carbonate to the linear carbonate in the organic solvent may be about 3: 7. In various aspects, the organic solvent may include a mixture of ethylene carbonate (cyclic carbonate) and ethyl methyl carbonate (linear carbonate). In this case, ethylene carbonate may account for greater than or equal to about 20% by weight or optionally about 25% by weight to less than or equal to about 40% by weight or optionally about 35% by weight of the electrolyte 28. In various aspects, ethylene carbonate may account for about 30% by weight of the electrolyte 28. Ethyl methyl carbonate may comprise greater than or equal to about 45 wt % or optionally about 50 wt % to less than or equal to about 70 wt %, optionally about 65 wt % or optionally about 60 wt % of electrolyte 28. In various aspects, ethyl methyl carbonate may comprise about 55 wt % of electrolyte 28.

[0097] The one or more co-solvents may include vinylene carbonate (VC), 1,3-propane sultone (PS), 1,3,2-dioxathiolane 2,2-dioxide (DTD), and combinations thereof.

[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 perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2) (LiBOB), lithium difluorooxalatoborate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonyl imide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 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 moles, or optionally about 0.6 moles and less than or equal to about 2.0 moles, or optionally about 1.5 moles. In various aspects, the lithium salt may be dissolved in an organic solvent at a concentration of about 1 mole. The lithium salt may account for greater than or equal to about 5 wt %, optionally about 8 wt %, or optionally about 10 wt % to less than or equal to about 20 wt %, optionally about 15 wt %, or optionally about 12 wt % of the electrolyte 28. In various aspects, the lithium salt may account for about 11 wt % of the electrolyte 28. In various aspects, the lithium salt may include LiPF6.

[0099] The functional additives are formulated to allow for in-situ formation of a solid electrolyte interface 44 on the surfaces 46 of the electroactive particles 40 of the negative electrode 22 during an initial charge and / or formation cycle of the battery 20 .

[0100] The functional additive includes a chemical compound containing a bis(trifluoromethanesulfonylimide) (TFSI) group and a substituted phenyl group, such as a monosubstituted phenyl group, a disubstituted phenyl group, a trisubstituted phenyl group or a combination thereof. The functional additive includes a chemical compound having the following formula (1):

[0101]

[0102] Where R 1 , R 2 and R 3 are independently hydrogen (H), alkyl (C n H 2n+1 ) or olefin group (C n H 2n ), wherein n is an integer greater than or equal to 1 and less than or equal to 20, or a halogen (e.g., Cl, F, Br and / or I). Alternatively, the chemical compound of formula (1) can be represented by the following linear formula: R1 R 2 R 3 C6H2N(SO2CF3)2.

[0103] In various aspects, in the chemical compound of formula (1), R 1 , R 2 and R 3 Each may be hydrogen and the functional additive may include N-phenyl-bis(trifluoromethanesulfonimide), CAS No. 37595-74-7.

[0104] On a per-gram basis, the functional additive may comprise greater than or equal to about 0.1 wt %, optionally about 0.3 wt %, or optionally about 0.5 wt % to less than or equal to about 5 wt %, optionally about 3 wt %, or optionally about 1.5 wt % of the electrolyte 28 .

[0105] Due to the chemical reaction between the functional additives in the electrolyte 28 and the electroactive particles 40 of the negative electrode 22, the solid electrolyte interface 44 is formed in situ on the surface 46 of the electroactive particles 40 of the negative electrode 22 during the initial charging process of the battery 20 and / or during the formation cycle of the battery 20. After the initial assembly of the battery 20, the potential at the negative electrode 22 is relative to Li / Li + The potential of the functional additive in the electrolyte 28 is greater than or equal to about 2 volts. During the initial charging process of the battery 20, lithium is embedded or otherwise inserted into the electroactive particles 40 of the negative electrode 22, which gradually reduces the potential at the negative electrode 22. When the potential of the negative electrode 22 is reduced to below the reduction potential of the functional additive, the functional additive in the electrolyte 28 is decomposed by an electrochemical reduction reaction, and its decomposition products are deposited on the surface 46 of the electroactive particles 40 to form a solid electrolyte interface 44. The reduction potential of the functional additive (relative to Li / Li + ) can be greater than or equal to about 1.5 volts, or optionally about 1.8 volts, and less than or equal to about 2.2 volts, or optionally about 2 volts. In various aspects, the reduction potential of the functional additive relative to Li / Li + can be about 1.9 volts. Therefore, during the initial charging of the battery pack 20, when the potential of the negative electrode 22 is relative to the Li / Li + When it drops below about 2.2 volts, for example, relative to Li / Li + When reduced to less than or equal to about 2 volts, the functional additive decomposes and forms a solid electrolyte interface 44 on the surface 46 of the electroactive particles 40 .

[0106] The solid electrolyte interface 44 formed in situ on the electroactive particles 40 includes the product of the electrochemical reduction of the chemical compound of formula (1). For example, the solid electrolyte interface 44 may include one or more chemical compounds having a bis(trifluoromethanesulfonylimide) group (-N(SO2CF3)2), a trifluoromethyl group (-CF3), a sulfur oxide group (-SOx), or a combination thereof. In various aspects, the solid electrolyte interface 44 may be substantially free of lithium fluoride (LiF), lithium-containing, phosphorus-containing and fluorine-containing compounds (e.g., Li x PF y ), lithium-containing, phosphorus-containing, fluorine-containing, and oxygen-containing compounds (e.g., Li x PF y O z ).

[0107] There are several significant benefits to using PTFE as the polymer matrix component 38 of the negative electrode 22. For example, using PTFE as the polymer matrix component 38 of the negative electrode 22 can allow the formation of a relatively thick negative electrode 22 with strong cohesive properties. In addition, when PTFE is used as the polymer matrix component 38 of the negative electrode 22, the negative electrode 22 can be formed by a dry process (e.g., hot pressing), and thus the need to use potentially toxic N-methylpyrrolidone (NMP) as a solvent in the manufacturing process can be eliminated, thereby reducing manufacturing costs. In addition, the high heat resistance and chemical resistance of PTFE can help extend the life of the battery 20. More importantly, PTFE can be fibrillated, and in this case, the PTFE fibers can achieve point contact or line contact with the surface 46 of the electroactive particles 40, while allowing lithium ions to flow between the electroactive particles 40 and the electrolyte 28, which can improve the rate capability of the battery 20. In addition, when fibrillated, the PTFE fibers can help form a strong cohesive network that binds the electroactive particles 40 and the conductive particles 42 in the negative electrode 22 together. The robust and flexible architecture and mechanical strength provided by using PTFE as the polymer matrix component 38 of the negative electrode 22 can be maintained over the life of the battery 20 to improve cycling stability. However, due to the low potential reached at the negative electrode 22 during charging, parasitic side reactions can occur between the PTFE and the lithium stored in the electroactive particles 40 during the charging process of the battery 20. Such side reactions can consume active lithium and thereby reduce the overall capacity of the battery 20.

[0108] The inventors of the present disclosure have discovered that forming a solid electrolyte interface 44 on the surface 46 of the electroactive particles 40 helps prevent or inhibit undesirable chemical reactions between the electroactive particles 40 and the polytetrafluoroethylene in the polymer matrix component 38 during cycling of the battery 20. In particular, forming the solid electrolyte interface 44 on the surface 46 of the electroactive particles 40 creates a physical barrier that shields the electroactive particles 40 from physical contact with the polytetrafluoroethylene in the polymer matrix component 38.

[0109] It is noteworthy that the inventors of the present disclosure have discovered that the reduction potential of the functional additive is higher than the reduction potential of the polytetrafluoroethylene in the polymer matrix component 38 of the negative electrode 22. Therefore, during the initial charging process of the battery 20, before the potential of the negative electrode 22 decreases to a sufficiently low level to initiate the decomposition of the polytetrafluoroethylene in the polymer matrix component 38, the solid electrolyte interface 44 will form on the surface 46 of the electroactive particles 40. Specifically, the inventors of the present disclosure have discovered that during the charging process of the battery 20, undesirable side reactions will not occur between the polytetrafluoroethylene in the polymer matrix component 38 and the electroactive particles 40 in the negative electrode 22 until the potential of the negative electrode 22 decreases relative to the Li / Li + to less than or equal to about 0.5 volts, which is significantly lower than the potential at which the functional additives in the electrolyte 28 decompose to form the solid electrolyte interface 44 (e.g., relative to Li / Li + of about 1.9 volts).

[0110] After initial assembly of the battery 20, the negative electrode 22 can be substantially free of lithium and a charge and discharge protocol can be performed to ensure that a solid electrolyte interface 44 is formed on the surface 46 of the electroactive particles 40. For example, a constant current and constant voltage (CCCV) protocol can be used to charge the battery 20. The CCCV charging protocol can include applying a constant current to the battery 20 at a charge rate less than or equal to about C / 20 until the battery 20 reaches a predetermined maximum potential Vmax (e.g., about 4.2V). A constant voltage can then be applied to the battery 20 at a predetermined maximum potential Vmax until the current reaches a charge rate less than or equal to about C / 50. The battery 20 can then be discharged to a predetermined minimum potential Vmin (e.g., about 2.7V) at a discharge rate of about C / 5.

[0111] Experimental

[0112] Semi-button cell preparation

[0113] Semi-coin cells including graphite electrodes were assembled and evaluated using cyclic voltammetry (CV) testing and constant current charge and discharge protocols. The graphite electrodes were prepared by hot pressing and had an areal capacity of approximately 5.5 mAh / cm 2, deposited on an 8 micron copper (Cu) foil current collector, dried in a vacuum at 140 degrees Celsius (°C), and cut into 14 millimeter (mm) discs. The graphite electrode comprises a mixture of graphite (G), carbon nanotubes (CNTs), and PTFE in a G:CNT:PTFE mass ratio of 97.7:0.8:1.5. The prepared electrolyte comprises a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in an EC:EMC mass ratio of 3:7, LiPF6 at a concentration of 1 mole, and 2% of vinylene carbonate (VC) based on the total weight of the electrolyte (benchmark electrolyte). The electrolyte according to an embodiment of the present disclosure is prepared by adding an additive consisting of N-phenyl-bis(trifluoromethanesulfonyl imide) (PhTFSI) to the benchmark electrolyte at a concentration of 3% based on the total weight of the electrolyte (PhTFSI-electrolyte).

[0114] Cyclic voltammetry test of half button cell

[0115] Cyclic voltammetry (CV) tests were performed on half coin cells including graphite electrodes at a temperature of about 25°C using a scan rate of 0.1 millivolt per second (mV / s). Figure 5 and Figure 6 is the measured current (milliamperes, mA) of the first cycle for half-coin cells including the baseline electrolyte (dashed line) and half-coin cells including PhTFSI-electrolyte (solid line) 100 vs. applied potential (volts, V vs. Li / Li + )200 cyclic voltammogram. During the CV test, the potential was negatively scanned from about 2.5 V to 0 V, where arrow 110 indicates the scanning direction of the positive scan. The curve with a measured current value of less than 0 mA on the y-axis depicts the reduction reaction occurring at the graphite electrode during the charging process and the insertion of lithium ions into the graphite electrode.

[0116] like Figure 5 As shown in , the measured current of the half coin cell including the reference electrolyte (dashed line) exhibits a reduction peak 120 starting from about 0.5 V, indicating that a side reaction occurs between PTFE and lithiated graphite (LiCx) at a potential of about 0.5 V during the charging process. Figure 6 yes Figure 5 Illustrations. Figure 6As shown in FIG. 1 , the measured current of the half coin cell including the PhTFSI-electrolyte (solid line) exhibits a reduction peak 130 starting from about 2.2 V and reaching a peak at about 1.9 V. Without wishing to be bound by theory, it is believed that the reduction peak 130 indicates that a reduction reaction is initiated between the PhTFSI additive in the electrolyte and the lithiated graphite at a potential of about 2.2 V during the charging process, and a solid electrolyte interface 44 is formed, which inhibits the subsequent side reaction between PTFE and the lithiated graphite at a potential of about 0.5 V, as shown in FIG. 1 . Figure 5 )of Figure 5 As evidenced by the absence of a reduction peak at 0.5 V in .

[0117] Constant current charge and discharge test of half button cell

[0118] A half-coin cell including a graphite electrode was charged and discharged at room temperature (e.g., 25° C.) using a Maccor cycler in a voltage range of 10 millivolts (mV) to 2 V. The half-coin cell was charged to a potential of about 10 mV using a constant current and constant voltage (CCCV) protocol at a constant current using a C / 20 charge rate, and then charged at a 10 mV constant voltage until the current reached C / 50. The half-coin cell was then discharged to 2 V at a C / 20 rate.

[0119] Figure 7 is the potential (V relative to Li / Li + ) 300 versus capacity (mAh) 400, depicting the charge curve 310 and discharge curve 320 of the first cycle of a half-coin cell including a baseline electrolyte (dashed line) and a half-coin cell including a PhTFSI-electrolyte (solid line). The circle 330 at a potential of about 1.9 V on the charge curve 310 represents the expected point during the charge process where the PhTFSI additive in the electrolyte decomposes to form the solid electrolyte interface 44. Figure 7 As shown in , the half-coin cell containing PhTFSI-electrolyte exhibits a significantly higher coulombic efficiency (CE) (CE is about 91%) than the half-coin cell containing the benchmark electrolyte (CE is about 68%). In addition, the electrochemical performance and charging cycle efficiency of the half-coin cell including the benchmark electrolyte are reduced by the side reaction between PTFE and lithium graphite (LiCx) starting from a potential of about 0.5 (indicated by arrow 340).

[0120] Full cell preparation and testing

[0121] Full pouch cells including a graphite negative electrode were assembled and evaluated using a galvanostatic charge and discharge protocol. The composition of the graphite negative electrode and electrolyte was the same as that of the semi-coin cell described above. The positive electrode had a capacity of approximately 4.75 mAh / cm 2The area capacity of the LiNi o.75 Mn 0.25 A mixture of O2 (NM75), Super P carbon black (SP), Ketjen black (KB) and PTFE.

[0122] The full cell was charged using a constant current and constant voltage (CCCV) protocol at a constant current using a C / 20 charge rate to a potential of about 4.2 V, and then charged at a constant voltage of 4.2 V until the current reached C / 50. The full cell was then discharged to 2.7 V at a C / 5 rate. Figure 8 is the potential (V relative to Li / Li + ) 500 versus capacity (mAh) 600, which depicts the charge curve 510 and discharge curve 520 of the first cycle of a full cell including a baseline electrolyte (dashed line) and a full cell including a PhTFSI-electrolyte (solid line). Figure 8 As shown in , the full cell containing PhTFSI-electrolyte exhibits significantly higher coulombic efficiency (CE of about 78%) than the full cell containing the benchmark electrolyte (CE of about 48%). In addition, the full cell containing PhTFSI-electrolyte has a higher total capacity than the full cell containing the benchmark electrolyte.

[0123] The above 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 appended 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 in any embodiment of the present disclosure can 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.

[0124] The terms used herein are only for the purpose of describing specific exemplary embodiments, and are not intended to be limiting. Unless the context clearly indicates otherwise, as used herein, the singular forms "one", "an" and "the" may be intended to also include plural forms. The terms "comprise", "include", "cover" and "have" are compatible, and therefore specify the presence of the 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 groups. Although the open term "comprising" should be understood as a non-limiting term for describing and claiming the various embodiments described herein, in some aspects, the term may be understood as alternatively being a more restrictive and limited term, such as "consisting of..." or "consisting essentially of...". Thus, for any given embodiment of a narration composition, material, assembly, element, feature, integer, operation and / or method step, the present disclosure also specifically includes an embodiment consisting of or essentially consisting of such narrated compositions, materials, assemblies, elements, features, integers, operations and / or method steps. In the case of “consisting of,” alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations, and / or method steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and / or method steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations, and / or method steps that do not materially affect the basic and novel characteristics may be included in the embodiments.

[0125] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless expressly identified as an order of performance. It is also to be understood that additional or alternative steps may be employed unless otherwise stated.

[0126] 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, engaged, connected, or coupled to another component, element, or layer, or there may be intervening elements or layers. In contrast, 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" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0127] Although the terms first, second, third, etc. can be used to describe various steps, elements, components, regions, layers and / or sections in this article, unless otherwise specified, these steps, elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish a step, element, component, region, layer or section from another step, element, component, region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in this article. Therefore, the first step, element, component, region, layer or section discussed below can be referred to as the second step, element, component, region, layer or section without departing from the teaching of exemplary embodiments.

[0128] For ease of description, spatial or temporal relative terms may be used herein, such as "before", "after", "inside", "outside", "below", "beneath", "lower", "above", "upper", etc. to describe the relationship of one element or feature to other (one or more) elements or (one or more) features as shown in the drawings. Spatially or temporally relative terms may be intended to encompass different orientations of a device or system in use or operation in addition to the orientation shown in the drawings.

[0129] Throughout this disclosure, numerical values ​​represent approximate measurements or range limits to cover slight deviations from given values ​​and embodiments having approximately the values ​​mentioned and embodiments having exactly the values ​​mentioned. Except in the working examples provided at the end of the detailed description, all numerical values ​​of (e.g., amounts or conditions) parameters in this specification (including the appended claims) should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. "About" means that the numerical value allows a certain slight imprecision (close to the exact value of the value to a certain extent; approximately or reasonably approximate the value; almost). If the imprecision provided by "about" is not otherwise understood in this ordinary sense in the art, then "about" as used herein refers to at least the deviation that can be caused by the common methods of measuring and using such parameters. For example, "about" may include 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% deviation. Furthermore, the disclosure of a range includes disclosure of all values ​​within the entire range and further subdivided ranges, including disclosure of endpoints and subranges given for that range.

[0130] As used herein, the terms "composition" and "material" are used interchangeably and refer generally to a substance that contains at least a preferred chemical constituent, element, or compound, but which may also contain additional elements, compounds, or substances, including trace impurities, unless otherwise specified. A composition or material "based on X" refers generally to a composition or material in which "X" is the single largest component of the composition or material in terms of weight percent (%). This can include compositions or materials having greater than 50 wt % X, as well as compositions or materials having less than 50 wt % X, as long as X is the single largest component of the composition or material based on its overall 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.

[0131] 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 possessed by the base metal element.

Claims

1. A battery pack for circulating lithium ions, the battery pack comprising: Positive electrode; a negative electrode spaced apart from the positive electrode, the negative electrode comprising a particulate component embedded in a polymer matrix component, the particulate component comprising electroactive negative electrode particles and the polymer matrix component comprising polytetrafluoroethylene; and An electrolyte that provides an ion-conducting path for the transfer of lithium ions between the positive electrode and the negative electrode, the electrolyte comprising: Organic solvents; Inorganic lithium salts; and Functional additives include chemical compounds containing bis(trifluoromethanesulfonylimide) groups and substituted phenyl groups.

2. The battery pack according to claim 1, wherein the functional additive comprises a chemical compound having the following formula (1): Where R 1 , R 2 and R 3 Each is independently hydrogen, alkyl, alkene or halogen.

3. The battery of claim 1 , wherein during an initial charge of the battery, the functional additive decomposes and forms a solid electrolyte interface on the surface of the electroactive negative electrode particles to isolate the electroactive negative electrode particles from physical contact with the polymer matrix component, and wherein, During subsequent cycling of the battery, the solid electrolyte interface prevents chemical reactions between the electroactive negative electrode particles and the polytetrafluoroethylene in the polymer matrix component.

4. The battery pack according to claim 3, wherein during the initial charging process of the battery pack, when the negative electrode is relative to Li / Li + At a potential of greater than or equal to about 1.5 volts and less than or equal to about 2.2 volts, the functional additive decomposes and forms the solid electrolyte interface on the surface of the electroactive negative electrode particles.

5. The battery of claim 1 , wherein the electroactive negative electrode particles have a solid electrolyte interface formed on a surface thereof, and wherein the solid electrolyte interface comprises one or more chemical compounds containing a bis(trifluoromethanesulfonylimide) group, a trifluoromethyl group, a sulfur oxide group, or a combination thereof. 6 . The battery of claim 1 , wherein the functional additive comprises greater than or equal to about 0.1 wt % to less than or equal to about 5 wt % of the electrolyte.

7. The battery according to claim 1, wherein the inorganic lithium salt comprises lithium hexafluorophosphate. 8 . The battery pack according to claim 1 , wherein the organic solvent comprises a mixture of ethylene carbonate and ethyl methyl carbonate.

9. The battery of claim 1, wherein the polymer matrix component comprises greater than or equal to about 90 weight percent polytetrafluoroethylene, and wherein the polymer matrix component comprises greater than or equal to about 1 weight percent to less than or equal to about 5 weight percent of the negative electrode.

10. The battery of claim 1, wherein the electroactive negative electrode particles comprise graphite, silicon, or a combination thereof.

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