Electrolyte formulation for ultra-fast rechargeable battery electric vehicle battery cells

Abstract

The present disclosure provides an electrolyte for a battery cell, a battery cell for a vehicle, and a method of forming an electrolyte. The electrolyte includes a carbonate solvent, a primary lithium salt present in the solvent at a concentration of 0.6 M to 2.0 M, an optional secondary lithium salt present in the solvent at a concentration of 0.1 M to 0.5 M. The electrolyte further includes a phenyl additive containing at least one of a fluoro-substituent and a fluorinated substituent, the phenyl additive present in an amount of 0.5 wt% to 20 wt% of the total weight of the electrolyte, and a co-additive present in an amount of 0.1 wt% to 20 wt% of the total weight of the electrolyte.

Description

Technical Field

[0001] This invention relates to the field of vehicle batteries, and more particularly to an electrolyte for battery cells and a method for preparing the same. Background Technology

[0002] Electric vehicle and hybrid electric vehicle technologies are achieved through the development and deployment of rechargeable secondary batteries that power the vehicle's powertrain. Secondary batteries, including lithium-ion batteries, typically consist of a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode provides the lithium-ion source and determines the battery's capacity and average voltage. The negative electrode stores lithium-ions and releases those received from the positive electrode when energy is needed. The separator prevents the positive and negative electrodes from contacting and prevents short circuits. The electrolyte provides the medium through which lithium-ions pass between the positive and negative electrodes.

[0003] Battery performance can be quantified by many properties, including energy density, power density, specific energy, specific power, charging rate, discharging rate, capacity decay, cycle life, thermal performance, and aging. Of particular interest is improving vehicle charging rates to reduce charging time. Depending on the charger type and the vehicle battery, vehicle charging rates can range from 20 minutes to two days or more. To improve charging rates and other metrics, the materials used to form the positive electrode, negative electrode, separator, and electrolyte, as well as the methods by which these materials are formed, have been the subject of numerous development efforts. These efforts include exploring various electrolyte additives.

[0004] Therefore, while existing electrolyte chemistry and other battery materials have achieved their intended purpose, there is still a need for new and improved electrolyte chemistry that can provide relatively improved charging rates and other performance metrics. Summary of the Invention

[0005] According to various aspects, this disclosure relates to an electrolyte for use in a battery cell. The electrolyte comprises: a carbonate solvent, a primary lithium salt (present in the solvent at a concentration of 0.6 M to 2.0 M, and including lithium hexafluorophosphate), and optionally a secondary lithium salt (present in the solvent at a concentration of 0.1 M to 0.5 M). The total concentration of the primary and secondary lithium salts (if present) is at most 2.0 M. The electrolyte further comprises: a phenyl additive and a co-additive containing at least one of a fluorinated substituent and a fluorinated substituent, the phenyl additive being present in an amount of 0.5 wt% to 20 wt% of the total weight of the electrolyte, and the co-additive being present in an amount of 0.1 wt% to 20 wt% of the total weight of the electrolyte, wherein the remaining weight percentage comprises the carbonate solvent, the primary lithium salt, and the secondary lithium salt, and the total weight of the electrolyte is 100 wt%.

[0006] In the above-described embodiments, the secondary lithium salt is lithium bis(fluorosulfonyl)imide.

[0007] In any of the above embodiments, the carbonate solvent comprises a mixture of ethylene carbonate present in 20 to 40 vol% of the solvent and a linear carbonate present in 60 to 80 vol% of the solvent, wherein the total volume percentage of the solvent is 100%. In other embodiments, ethyl acetate is present in 1 to 20 vol% of the solvent, wherein the total volume percentage of the solvent is 100%. In still other embodiments, the linear carbonate comprises at least one selected from ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate.

[0008] In any of the above embodiments, the phenyl additive is fluorobenzene. Alternatively or additionally, in any of the above embodiments, the phenyl additive has the following formula:

[0009]

[0010] Among them, R 1 R 2 R 3 R 4 R 5 and R 6 At least one of them is fluorine, a fluorinated alkyl group having 1 to 10 carbons, and a fluorinated alkoxy group having 1 to 10 carbons, and R 1 R 2 R 3 R 4 R 5 R 6 The remaining portion (if present) is independently selected from hydrogen, halogens other than fluorine, alkyl groups having 1 to 10 carbons, methoxy groups, vinyl groups, propargyl groups, alkynyl groups having 1 to 10 carbons, benzyl groups, hydroxyl groups, alkoxy groups having 1 to 10 carbons, alkenyloxy groups having 1 to 10 carbons, alkynyloxy groups having 1 to 10 carbons, aryloxy groups having 1 to 10 carbons, heterocyclic alkoxy groups having 1 to 10 carbons and at most 2 rings, heterocyclic alkoxy groups having 1 to 10 carbons, oxo groups, carboxyl groups, ester groups, and ether groups. In other embodiments, R 1 R 2 R 3 R 4 R 5 R 6 At least one of them is C n H x F y CH2C n H x F y CH2OC n H x F y and CF2OC n H x F yWhere n is in the range of 1 to 5, x is in the range of 0 to 11, and y is in the range of 1 to 11.

[0011] In any of the above embodiments, the co-additives include at least one of vinylene carbonate, 1,3,2-dioxathiolane 2,2-dioxide, lithium difluoro(oxalate)borate, and fluoroethylene carbonate.

[0012] According to various additional aspects, this disclosure relates to a battery cell for a vehicle. The battery cell includes: a positive electrode comprising a positive electrode disposed on a positive current collector; a negative electrode comprising a negative electrode disposed on a negative current collector; a separator disposed between the positive and negative electrodes; and an electrolyte in contact with the positive electrode, the negative electrode, and the separator. The electrolyte includes the electrolyte described according to any of the above embodiments. In some embodiments, the electrolyte comprises: a carbonate solvent, a primary lithium salt (present in the solvent at a concentration of 0.6 M to 2.0 M, and comprising lithium hexafluorophosphate), a secondary lithium salt (present in the solvent at an amount of 0.1 M to 0.5 M, and comprising lithium bis(fluorosulfonyl)imide) (wherein the total amount of the primary and secondary lithium salts is 2.0 M), a phenyl additive (present in an amount of 0.5 wt% to 20 wt% of the total weight of the electrolyte, and comprising at least one of fluorinated and fluorinated substituents), and a co-additive (present in an amount of 0.1 wt% to 20 wt% of the total weight of the electrolyte), wherein the remaining weight percentages are carbonate solvent, primary lithium salt, and secondary lithium salt, and the total weight of the electrolyte is 100 wt%.

[0013] In the above embodiments, the carbonate solvent comprises a mixture of ethylene carbonate present in 20 to 40 vol% of the solvent and a linear carbonate present in 60 to 80 vol% of the solvent, wherein the total volume percentage of the solvent is 100%.

[0014] In any of the above embodiments, the linear carbonate includes at least one of ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate.

[0015] In any of the above embodiments, the carbonate solvent comprises ethyl acetate present at 1 to 20 vol% of the solvent, wherein the total volume percentage of the solvent is 100%.

[0016] In any of the above embodiments, the phenyl additive is fluorobenzene. Alternatively or additionally, the phenyl additive has the following formula:

[0017]

[0018] Among them, R 1 R 2 R3 R 4 R 5 and R 6 At least one of them is fluorine, a fluorinated alkyl group having 1 to 10 carbons, and a fluorinated alkoxy group having 1 to 10 carbons, and R 1 R 2 R 3 R 4 R 5 R 6 The remaining portion (if present) is independently selected from hydrogen, halogens other than fluorine, alkyl groups having 1 to 10 carbons, methoxy groups, vinyl groups, propargyl groups, alkynyl groups having 1 to 10 carbons, benzyl groups, hydroxyl groups, alkoxy groups having 1 to 10 carbons, alkenyloxy groups having 1 to 10 carbons, alkynyloxy groups having 1 to 10 carbons, aryloxy groups having 1 to 10 carbons, heterocyclic alkoxy groups having 1 to 10 carbons and at most 2 rings, heterocyclic alkoxy groups having 1 to 10 carbons, oxo groups, carboxyl groups, ester groups, and ether groups. In other embodiments, R 1 R 2 R 3 R 4 R 5 R 6 At least one of them is C n H x F y CH2C n H x F y CH2OC n H x F y and CF2OC n H x F y , where n is in the range of 1 to 5, x is in the range of 0 to 11, and y is in the range of 1 to 11.

[0019] In any of the above embodiments, the negative electrode is graphite, and the co-additives include: vinylene carbonate (present in 1% to 5% by weight of the total electrolyte), 1,3,2-dioxazothiophene-2,2-dioxide (present in 0.1% to 5% by weight of the total electrolyte), lithium difluoro(oxalate)borate (present in 0.1% to 5% by weight of the total electrolyte), and optionally fluoroethylene carbonate (present in 0.1% to 5% by weight of the total electrolyte).

[0020] In the above alternative embodiments, the negative electrode is a silicon compound and graphite, wherein the silicon compound is present at 5% to 20% by weight of the negative electrode, and the graphite is present at 80% to 95% by weight of the negative electrode, the total weight percentage of the negative electrode is 100%, wherein the silicon compound includes silicon, lithium-ion silicon, and silicon oxide (SiO2). x The additives include at least one of the following: lithium-ion silicon oxide, silicon-carbon (SiC), and silicon alloys, wherein x is in the range of 1 to 2.

[0021] In other alternative embodiments described above, the negative electrode is a silicon compound and graphite, wherein the silicon compound is present at 21% to 50% by weight of the negative electrode, and the graphite is present at 50% to 79% by weight of the negative electrode, with the total weight percentage of the negative electrode being 100%. The silicon compound includes silicon, lithium-ion silicon, and silicon oxide (SiO2). x The additives include at least one of the following: lithium silicon oxide, silicon carbide (SiC), and silicon alloy, wherein x is in the range of 1 to 2.

[0022] According to various other aspects, this disclosure relates to a method for forming an electrolyte. The method includes: a carbonate solvent, a primary lithium salt (present in the solvent at a concentration of 0.6 M to 2.0 M, and comprising lithium hexafluorophosphate), an optional secondary lithium salt (present in the solvent, when present, at an amount of 0.1 M to 0.5 M) (wherein the total concentration of the primary and secondary lithium salts is 2.0 M), a phenyl additive (present in an amount of 0.5 wt% to 20 wt% of the total weight of the electrolyte, and comprising at least one of fluorinated and fluorinated substituents), and a co-additive (present in an amount of 0.1 wt% to 20 wt% of the total weight of the electrolyte), wherein the remaining weight percentages are the carbonate solvent, the primary lithium salt, and the secondary lithium salt, and the total weight of the electrolyte is 100 wt%. Attached Figure Description

[0023] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0024] Figure 1 A vehicle and powertrain including a secondary battery according to an embodiment of this disclosure are shown.

[0025] Figure 2A A battery according to an embodiment of this disclosure is shown.

[0026] Figure 2B A pouch-shaped or prismatic battery cell according to an embodiment of the present disclosure is shown.

[0027] Figure 2C A cylindrical battery cell according to an embodiment of the present disclosure is shown.

[0028] Figure 2D A coin-shaped battery cell according to an embodiment of the present disclosure is shown.

[0029] Figure 3 A method for forming a battery cell comprising a phenyl additive in an electrolyte according to an embodiment of the present disclosure is shown, said phenyl additive comprising at least one of a fluorinated substituent and a fluorinated substituent.

[0030] Figure 4 The state of charge (percentage) on the vertical y-axis relative to time (minutes) on the horizontal x-axis, as measured at 25°C according to an embodiment of this disclosure, is shown.

[0031] Figure 5 The diagram illustrates the functional relationship between the capacity retention rate (percentage) on the vertical y' axis and the coulombic efficiency (percentage) on the vertical y'" axis according to embodiments of this disclosure and the number of cycles.

[0032] Figure 6 The state of charge (percentage) on the vertical y-axis relative to time (minutes) on the horizontal x-axis, as measured at 25°C according to an embodiment of this disclosure, is shown.

[0033] Figure 7 A graph showing the relationship between the capacity retention rate (percentage) on the vertical y' axis and the coulombic efficiency (percentage) on the vertical y'" axis as a function of the number of cycles is shown according to an embodiment of the present disclosure. Detailed Implementation

[0034] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its uses. Furthermore, it is not intended to be bound by any express or implied theory presented in the foregoing background, summary of the invention, or the following detailed description. It should be understood that throughout the drawings, corresponding reference numerals denote similar or corresponding parts and features.

[0035] Reference will now be made in detail to several embodiments of the present disclosure illustrated in the accompanying drawings. Wherever possible, the same or similar reference numerals are used in the drawings and description to refer to the same or similar parts or steps. The drawings are simplified and not drawn to scale.

[0036] This disclosure relates to an electrolyte containing a phenyl additive (the phenyl additive includes at least one of fluorinated and fluorinated substituents), a battery cell for a vehicle including the electrolyte, a method for forming the electrolyte, and a method for forming a solid electrolyte interface film on a negative electrode. The battery cell includes any battery cell platform, such as a prismatic, pouch, cylindrical, or coin-shaped battery cell. The battery cell can achieve an ultra-fast 6C charging rate, where 6C is understood as an 8-minute charging rate from 0% capacity to 80% capacity. This battery can be used in electric or hybrid electric vehicles.

[0037] As used herein, the term "vehicle" is not limited to motor vehicles. While this technology is described primarily in conjunction with electric vehicles and hybrid electric vehicles, it is not limited to electric vehicles and hybrid electric vehicles. These concepts can be used in a wide variety of applications (e.g., applications related to components used in motorcycles, mopeds, locomotives, aircraft, ships, and other vehicles) and in other applications using batteries, such as consumer electronics, mobile power supplies for buildings, portable power stations for powering remote work sites, emergency backup power supplies, and permanent power stations associated with buildings and equipment, all of which can be powered by, for example, solar or wind power systems, transmission lines, and fuel generators (e.g., gasoline, propane, kerosene, or diesel generators and Stirling engines).

[0038] Figure 1 A vehicle 100 including a propulsion system 120 is shown. The propulsion system 120 typically includes an electric motor 124 and a secondary battery 126 for supplying power to the electric motor 124. Furthermore, in many embodiments, the propulsion system 120 includes an inverter 128 for converting power from DC (direct current) supplied by the battery 126 to AC (alternating current) used by the electric motor 124. The inverter 128 may be included in a power electronics module 130, which includes, for example, transistors and diodes, for switching power from DC to AC and vice versa.

[0039] Controller 132 is connected to inverter 128 and is programmed to control and manage the operation of electric motor 124 and related hardware (including inverter 128). Electric motor 124 is connected to transmission (drive unit) 136 and drivetrain 138, which transmits mechanical power and rotation to wheels 140 of vehicle 100. Controller 132 includes one or more processors and tangible non-transitory memory 134. A combustible fuel-powered engine may also be included in the propulsion system of the hybrid electric vehicle.

[0040] Referring again to motor 124, the motor 124, powered by battery 126, includes a stator 142 and a rotor 144 disposed within the stator 142. The stator 142 is the stationary portion of the motor 124. The stator 142 provides a rotating magnetic field, and the stationary magnetic field of the rotor 144 attempts to align with this rotating magnetic field, causing the rotor 144 to rotate in a so-called "electric" mode. In other applications, the rotating field of the rotor 144 (caused by physical rotation) generates an electric current in the stator 142—this mode of operation is called "generating electricity," and the motor 124 used in this manner is called a generator. In traction motor vehicle applications, the electric mode provides motion to the vehicle 100. When the vehicle is stationary, the generating mode harvests some energy recovered from braking and stores it back in the vehicle battery 126.

[0041] refer to Figure 2A , Figure 2B , Figure 2C and Figure 2D These diagrams illustrate the use of electric vehicles 100 (e.g., Figure 1 An embodiment of a secondary battery 126 powered by an electric vehicle 100 is shown. As described above, the secondary battery 126 is understood as a rechargeable battery that can discharge when a load is applied and recharge when an external power source is applied. (See reference...) Figure 2A , Figure 2B , Figure 2C and Figure 2D Battery 126 is shown connected to a load 148, such as electric motor 124. However, other loads 148 include various systems in vehicle 100, such as climate control systems and infotainment systems. Battery 126 includes one or more battery cells 150 assembled together. Battery cells 150 may be, for example, pouch-shaped, prismatic, cylindrical, or coin-shaped battery cells, which will be discussed further below. Reference Figures 2B to 2DWhen load 148 is applied to battery 126, Li+ ions move from negative electrode 158 to positive electrode 156 through electrolyte 162 and separator 160. Equivalent electrons (e-) move from positive electrode 156 to negative electrode 158 through circuit 146, providing voltage to load 148. During charging, when an external voltage is applied, Li+ ions move from positive electrode 156 to negative electrode 158 through electrolyte 162 and separator 160, and can be embedded in negative electrode 158.

[0042] Each battery cell has 150 (such as) Figure 2B , Figure 2C and Figure 2D The cells shown typically include a positive current collector 152, a positive electrode 156 disposed on the positive current collector 152, a negative current collector 154, a negative electrode 158 disposed on the negative current collector 154, a separator 160 disposed between the positive electrode 156 and the negative electrode 158, and an electrolyte 162. While the illustrated battery cell 150 includes one negative electrode 158 (and one negative current collector 154) and one positive electrode 156 (and one positive current collector 152), the battery cell 150 may optionally include two or more positive electrodes 156 (and one or more positive current collectors 152) and one or more negative electrodes 158 (and one or more negative current collectors 154). In other alternative embodiments, the battery cell 150 may include one or more positive electrodes 156 (and one or more positive current collectors 152) and two or more negative electrodes 158 (and two or more negative current collectors 154). In any of the above designs, one or more diaphragms 160 are staggered between the positive electrode 156 and the negative electrode 158 to prevent the positive electrode 156 and the negative electrode 158 from contacting each other.

[0043] In some implementation schemes, Figure 2BThe battery cell 150 is configured as a pouch-shaped battery cell or a prismatic battery cell. In any design in which multiple positive electrodes 156 and multiple negative electrodes 158 are present, a separator 160 is disposed between the positive electrodes 156 and the negative electrodes 158. In some embodiments, the strip-shaped separator 160 may be folded in a Z-shape around each positive electrode 156 (and positive current collector 152) and each negative electrode 158 (and negative current collector 154). In the pouch-shaped battery cell, tabs 164 are welded to the positive current collector 152 and the negative current collector 154. Alternatively, tabs 164 with the positive current collector 152 and the negative current collector 154 are integrally formed by cutting tabs 164 with the positive current collector 152 and the negative current collector 154 from a larger sheet of raw material. In addition, the cover 166 is in the form of a flexible thin film pouch formed of aluminum or other materials. On the other hand, the prismatic battery cell includes terminals connected to the positive current collector 152 and the negative current collector 154, and the cover 166 is formed of a relatively rigid shell, typically in the form of a cuboid. The tabs 164 or terminals connected to the positive current collectors 152 from the plurality of battery cells 150 are, for example, via a busbar 168 (see...). Figure 2A ) or other electrical connections are made together and connected to the tabs 164 or terminals of the negative current collectors 154 from the plurality of battery cells 150, for example via busbars 169 (see Figure 2A (or other electrical connections) are connected together.

[0044] Alternatively, Figure 2C The battery cell 150 is configured as a cylindrical battery cell 150. In this design, the positive current collector 152, the negative current collector 154, the positive electrode 156, the negative electrode 158, and one or more separators 160 are in the form of long strips, which are rolled into cylinders or jelly rolls. Similar to the prismatic battery cell, the cover 166 is formed of a relatively rigid shell of aluminum or other materials. The tabs 164 are welded to the positive current collector 152 and the negative current collector 154. The tabs 164 connected to the positive current collectors 152 from multiple battery cells 150 are, for example, via busbars 168 (see...). Figure 2A ) or other electrical connections are made together and connected to the tabs 164 or terminals of the negative current collectors 154 from the plurality of battery cells 150, for example via busbars 169 (see Figure 2A (or other electrical connections) are connected together.

[0045] In an alternative implementation, the battery cell 150 is packaged in, for example... Figure 2DIn the coin-shaped battery cell shown, a positive current collector 152, a negative current collector 154, a positive electrode 156, a negative electrode 158, and one or more separators 160 are in the form of a disc, sandwiched together in a coin package forming a cover 166, which includes a cap 170 and a can 172. A spring washer 174 may be included between the positive current collector 152 and the cap 170. Electrolyte 162 is added to the battery cell 150 before the cap 170 is secured to the can 172. The cap includes terminals 164 for the negative electrode 158 and the positive electrode 156.

[0046] In the various types of battery cells 150 described above, the positive current collector 152 and the negative current collector 154 are formed of conductive materials. In some embodiments, the positive current collector 152 comprises aluminum. Alternatively or additionally, the positive current collector 152 may comprise copper-clad aluminum and stainless steel. In some embodiments, the negative current collector 154 comprises copper. Alternatively or additionally, the negative current collector 154 may comprise nickel, stainless steel, and titanium. Current collectors 152 and 154 are shown in the form of foil; however, it should be understood that other forms, such as mesh, may be presented. In some embodiments, the foil positive current collector 152 and the foil negative current collector 154 are gas impermeable. The thickness of the positive current collector 152 is from 5 micrometers to 50 micrometers, including all values ​​and ranges therein, for example, from 5 micrometers to 25 micrometers. The thickness of the negative current collector 154 is from 4 micrometers to 50 micrometers, including all values ​​and ranges therein, for example, from 4 micrometers to 25 micrometers.

[0047] The positive electrode 156 includes lithium ions (Li... + The cathode material can undergo reversible insertion or intercalation of lithium ions, thereby determining, for example, the battery capacity and average voltage. In some embodiments, the cathode material includes lithium iron phosphate, which has an olivine-type structure. Additionally or alternatively, the cathode material includes lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel manganese oxide, lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese aluminum oxide, which also have an olivine-type structure. In some embodiments, the lithium nickel manganese cobalt oxide has the formula LiNi a Mn b Co c O2, where the sum of a, b, and c is 1, for example, LiNi. 0.33 Mn 0.33 Co 0.33 O2(NMC111), LiNi 0.5 Mn 0.3 Co 0.2 O2(NMC523), LiNi 0.6 Mn 0.2 Co 0.2 O2(NMC622), LiNi 0.7 Mn0.2 Co 0.1 O2(NMC721), LiNi 0.75 Mn 0.25 O2 (NM75) and LiNi 0.8 Mn 0.1 Co 0.1 O2 (NMC811). In other embodiments, the lithium manganese oxide cathode Li2Mn2O4 is a spinel-type cathode.

[0048] In some embodiments, the cathode material is deposited on the cathode current collector 152 at a density of 1.5 mA-h / cm² to 5 mA-h / cm² (inclusive of all values ​​and ranges therein, e.g., 1.7 mA-h / cm² to 3.5 mA-h / cm²). The cathode material comprises particles with a particle size (maximum linear cross-section measured by optical microscopy) ranging from 5 nanometers to 50 micrometers (inclusive of all values ​​and ranges therein). Furthermore, in some embodiments, the olivine-type cathode particles are coated with carbon particles. The carbon particles are present at 0.9% to 2% by weight of the total cathode particles.

[0049] When the positive electrode material is formed on one side of the positive electrode current collector 152, the thickness of the positive electrode 151, including both the positive electrode current collector 152 and the positive electrode 156, is 10 micrometers to 500 micrometers, including all values ​​and ranges therein. When the positive electrode material is formed on both sides of the positive electrode current collector 152, the thickness of the positive electrode is 30 micrometers to 1050 micrometers, including all values ​​and ranges therein (for a dual-sided positive electrode), for example, 205 micrometers to 500 micrometers.

[0050] The negative electrode 158 comprises a material capable of undergoing reversible insertion or intercalation of lithium ions at a lower electrochemical potential than that of the positive electrode 156 material, thereby creating an electrochemical potential difference between the negative electrode 158 and the positive electrode 156. In some embodiments, the negative electrode material comprises graphite optionally combined with a silicon compound. In some embodiments, the graphite comprises at least one of pure graphite and surface-modified artificial graphite. In other embodiments, the graphite is modified with at least one of hard carbon (also known as non-graphitized carbon or coke) and soft carbon (also known as graphitized carbon). In some embodiments, the average D50 particle size of the graphite is from 6 micrometers to 20 micrometers. Additionally, the surface area of ​​the graphite is from 1 m² / g to 120 m² / g (measured by Brunauer-Emmett-Teller (BET) surface area analysis). The graphite also has a Gra weight percentage of 50 wt% to 100 wt%. Furthermore, the tap density of the graphite is from 0.5 g / cm³ to 1.5 g / cm³, including all values ​​and ranges therein.

[0051] In other embodiments, the negative electrode material includes: graphite present in an amount of 50 wt% to 100 wt% (including all values and ranges therein) of the total weight of the negative electrode, and a silicon compound present in an amount of 0 wt% to 50 wt% (including all values and ranges therein, such as 0.1 wt% to 50 wt%) of the total weight of the negative electrode, wherein the total weight of the negative electrode is 100%. In other embodiments, the negative electrode material includes: graphite present in an amount of 80 wt% to 95 wt% (including all values and ranges therein) of the total weight of the negative electrode, and a silicon compound present in an amount of 5 wt% to 20 wt% (including all values and ranges therein) of the total weight of the negative electrode, wherein the total weight of the negative electrode is 100%. In alternative embodiments, the negative electrode material includes: graphite present in an amount of 50 wt% to 79 wt% (including all values and ranges therein) of the total weight of the negative electrode and a silicon compound present in an amount of 21 wt% to 50 wt% (including all values and ranges therein) of the total weight of the negative electrode. The silicon compound includes at least one of silicon, silicon oxide (SiO x , where x ranges from 1 to 2), lithiated silicon oxide (LSO), silicon carbide (SiC), and silicon alloys (such as silicon titanium (SiTi), silicon niobium (Si-Nb), and silicon aluminum (Si-Al)). The chemical formula of the lithiated silicon oxide is Li y SiO x , where x ranges from 0 to 2 and y ranges from 0 to 1. The average particle size of the lithiated silicon oxide is 3 μm < D50 < 20 μm. The lithiated silicon oxide also has a surface area of 0.5 m² / g to 10 m² / g (measured by Brunauer-Emmett-Teller (BET) surface area analysis). In addition, the tapped density of the lithiated silicon oxide is 0.8 g / cm³ to 1.5 g / cm³, including all values and ranges therein. The silicon content of the silicon carbide is 30 wt% to 60 wt% of the silicon carbide, including all values and ranges therein. The average particle size of the silicon carbide is 3 μm < D50 < 20 μm. The silicon carbide also has a surface area of 0.5 m² / g to 10 m² / g (measured by Brunauer-Emmett-Teller (BET) surface area analysis). In addition, the TD density of the silicon carbide is 0.6 g / cm³ to 1.5 g / cm³, including all values and ranges therein. Additionally or alternatively, the negative electrode material includes one or more of tin oxides; aluminum; indium; zinc; germanium; and titanium oxide, and any combination of the above.

[0052] In some embodiments, the negative electrode material is deposited on the negative electrode current collector 154 at a density of 1.65 mA-h / cm² to 5.5 mA-h / cm² (inclusive of all values ​​and ranges therein, e.g., 1.87 mA-h / cm² to 3.85 mA-h / cm²). Further, the compressed density (pressed density) of the negative electrode material is 1.3 g / cm³ to 2 g / cm³, inclusive of all values ​​and ranges therein, e.g., 1.5 g / cm³ to 1.7 g / cm³.

[0053] In some embodiments, the thickness of the negative electrode 158 is from 10 micrometers to 550 micrometers, including all values ​​and ranges therein. In some embodiments, the negative electrode 158 is applied to the negative electrode current collector 154 using a deposition process (e.g., a slurry-based process, a hot roll forming process, extrusion, or additive manufacturing) to form a coating on the negative electrode current collector 154. The combined negative electrode 158 and negative electrode current collector 154 provide a negative electrode electrode, as further mentioned herein.

[0054] The separator 160 is a porous material formed of an electrically insulating material that prevents contact between the positive electrode 156 and the negative electrode 158 and potential short circuits. The separator 160 is sandwiched or at least partially surrounded between the positive electrode 156 and the negative electrode 158, allowing lithium ions and electrolyte 162 to pass through the pores of the separator 160. The separator 160 may comprise one or more of composite materials, polymeric materials, and nonwoven materials. In some embodiments, the separator comprises at least one of polyethylene, polypropylene, polyamide, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride. Additionally, the separator 160 may be filled, i.e., include one or more fillers dispersed therein, wherein the one or more fillers comprise materials (e.g., glass fiber, nonwoven fabric, or woven cloth). In additional or alternative embodiments, the separator 160 may comprise at least one of a thermally stable porous polymer coating and a ceramic coating (e.g., an alumina coating). This coating is disposed on one or more surfaces of a porous polymer membrane selected from at least polyethylene and polypropylene. The diaphragm 160 may comprise one or more layers, wherein each layer is formed of one or more of the materials described above. The diaphragm 160 may be in the form of a membrane or a mesh, such as a woven mesh or a cut membrane. In some embodiments, the thickness of the diaphragm 160 is from 4 micrometers to 25 micrometers, including all values ​​and ranges therein.

[0055] Electrolyte 162 provides a medium for lithium ion passage between the positive electrode 156 and the negative electrode 158. Electrolyte 162 is a liquid electrolyte permeating the membrane 160 and typically comprises a primary lithium salt and optional secondary lithium salts dissolved in a carbonate solvent having a phenyl additive and co-additives, the phenyl additive comprising at least one of fluorinated and fluorinated substituents. The addition of the phenyl additive is believed to reduce the viscosity of the carbonate solvent and improve the surface wettability of the electrolyte with the positive electrode 156. Furthermore, the phenyl additive is believed to facilitate the formation of a lithium fluoride solid electrolyte interface at the negative electrode 158. The addition of the phenyl additive is also believed to increase the charging rate of the battery cell to a maximum of 6C.

[0056] The primary lithium salt includes lithium hexafluorophosphate (LiPF6). Lithium hexafluorophosphate is present in the solvent at a concentration (moles of salt per liter of solvent) from 0.6 mol (M) to 2.0 M (inclusive of all values ​​and ranges, e.g., 0.9 M). If the electrolyte 162 includes a secondary lithium salt, then the secondary lithium salt includes lithium bis(fluorosulfonyl)imide (LiFSI). Additionally or alternatively, the lithium secondary salt includes one or more of the following: lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSA: lithium bis(trifluoromethanesulfonyl)azanide). The lithium secondary salt (if present) is present in the solvent at a concentration (moles of salt per liter of solvent) of 0.1 M to 0.5 M (inclusive of all values ​​and ranges therein, e.g., 0.3 M). The total concentration of the primary and secondary lithium salts (if present) is at most 2.0 M, including all values ​​and ranges from 0.6 M to 2.0 M, such as 1.2 M. In some embodiments, for example, the primary lithium salt is present at 1.2 M. In another embodiment, the primary lithium salt, namely lithium hexafluorophosphate (LiPF6), is present at 0.9 M, and the secondary lithium salt, namely lithium bis(fluorosulfonyl)imide (LiFSI), is present at 0.3 M. The combination of lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) is believed to enhance lithium-ion conductivity.

[0057] In some embodiments, the non-aqueous organic solvent includes cyclic carbonates, linear carbonates, and optionally aliphatic carboxylic acid esters. Cyclic carbonates include ethylene carbonate (EC). Additionally or alternatively, cyclic carbonates include propylene carbonate (PC). The cyclic carbonates are present at 20% to 40% by volume of the total solvent volume (inclusive of all values ​​and ranges therein, e.g., 30% by volume).

[0058] Linear carbonates include at least one of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). The linear carbonates are present at 60% to 80% by volume of the total solvent volume (inclusive of all values ​​and ranges therein, e.g., 70% by volume). The use of linear carbonates has been found to reduce solvent viscosity and improve the charging rate capability of battery cells.

[0059] Aliphatic carboxylic acid esters include ethyl acetate (EA). Alternatively or additionally, aliphatic carboxylic acid esters include at least one of methyl acetate, propyl propionate, butyl acetate, isoamyl acetate, methyl butyrate, and ethyl butyrate. If present in a carbonate solvent, the aliphatic carboxylic acid ester is present in an amount of 1% to 20% by volume. In some embodiments, the aliphatic carboxylic acid ester is added to the electrolyte, wherein battery formation occurs at temperatures below 50 degrees Celsius (°C), for example, in the range of 20°C to 49°C, including all values ​​and increments, because aliphatic carboxylic acid esters typically reduce the viscosity of the solvent. At temperatures above 50 degrees Celsius (°C), for example, in the range of 50°C to 80 degrees Celsius (°C), the aliphatic carboxylic acid ester may be omitted. Battery formation is understood as a process following the assembly of battery cells or batteries, wherein the battery cells are electrically connected and begin an initial charge, followed by repeated charge and discharge cycles. During the formation of the solid electrolyte interface in a battery (e.g., lithium fluoride formation, positive electrode electrolyte interface formation), structural changes occur in the positive and negative electrode materials, and in some embodiments, the positive and negative electrode current collectors corrode or dissolve. It has also been found that using ethyl acetate can reduce the viscosity of the solvent and improve the charging rate capability of the battery cell.

[0060] In some embodiments, the phenyl additive includes fluorobenzene. Additionally or alternatively, the phenyl additive has the following composition:

[0061]

[0062] Among them, R 1 R 2 R 3 R 4 R 5 R 6At least one of them is selected from fluorine, fluorinated alkyl groups having 1 to 10 carbons, and fluorinated alkoxy groups having 1 to 10 carbons. In some embodiments, R 1 R 2 R 3 R 4 R 5 and R 6 One, two, three, four, five, or all of them are independently selected from fluorine, fluorinated alkyl groups having 1 to 10 carbons, and fluorinated alkoxy groups having 1 to 10 carbons. In other embodiments, R 1 R 2 R 3 R 4 R 5 R 6 At least one of them is C n H x F y CH2C n H x F y CH2OC n H x F y and CF2OC n H x F y Wherein, n is in the range of 1 to 5, x is in the range of 0 to 11, and y is in the range of 1 to 11. Phenyl additives comprising at least one fluorinated substituent have been found to improve interfacial wettability between the electrolyte and the positive and negative electrodes, contributing to the provision of lithium-rich solid electrolyte interfaces on graphite negative electrodes including silicon carbide, and enhancing lithium-ion transport capacity and extending cycle performance.

[0063] R 1 R 2 R 3 R 4 R 5 R 6 The remaining portion (if present) is independently one of hydrogen, a halogen other than fluorine, an alkyl group having 1 to 10 carbons, a methoxy group, a vinyl group, a propargyl group, an alkynyl group having 1 to 10 carbons, a benzyl group, a hydroxyl group, an alkoxy group having 1 to 10 carbons, an alkenyloxy group having 1 to 10 carbons, an alkynyloxy group having 1 to 10 carbons, an aryloxy group having 1 to 10 carbons, a heterocyclic alkoxy group having 1 to 10 carbons and at most 2 rings, a heterocyclic alkoxy group having 1 to 10 carbons, an oxo group, a carboxyl group, an ester group, and an ether group. It is understood that if R 1 R 2 R 3 R 4 R 5 and R 6If all of them are independently selected from fluorine, fluorinated alkyl groups having 1 to 10 carbons, and fluorinated alkoxy groups having 1 to 10 carbons, then R 1 R 2 R 3 R 4 R 5 and R 6 The remaining part will not exist.

[0064] Furthermore, the electrolyte 162 includes one or more co-additives, including at least one of the following: ethylene ethylene carbonate (VC), 1,3,2-dioxazolthiophene-2,2-dioxide (DTD), lithium difluoro(oxalate)borate (LiDFOB), fluoroethylene carbonate (FEC), and combinations thereof. In some embodiments, the electrolyte includes ethylene ethylene carbonate (VC), 1,3,2-dioxazolthiophene-2,2-dioxide (DTD), lithium difluoro(oxalate)borate (LiDFOB), and optionally fluoroethylene carbonate (FEC). In such embodiments, ethylene ethylene carbonate (VC) is present at 1% to 5% by weight (inclusive of all values ​​and ranges therein, e.g., 5% by weight) of the total electrolyte weight; 1,3,2-dioxazothiophene-2,2-dioxide (DTD) is present at 0.1% to 5% by weight (inclusive of all values ​​and ranges therein, e.g., 0.5% by weight) of the total electrolyte weight; lithium difluoro(oxalate)borate (LiDFOB) is present at 0.1% to 5% by weight (inclusive of all values ​​and ranges therein, e.g., 0.5% by weight) of the total electrolyte weight; and fluoroethylene carbonate (FEC) (if present) is present at 0.1% to 20% by weight (inclusive of all values ​​and ranges therein, e.g., 0.1% to 5%, 5%, or 15% by weight) of the total electrolyte weight. It should be understood that the total weight of the electrolyte includes the solvent, lithium salt, phenyl additives, and co-additives, totaling 100% by weight.

[0065] Regarding fluoroethylene carbonate (FEC), in embodiments where the negative electrode comprises graphite but does not contain silicon compounds, fluoroethylene carbonate (FEC) may be omitted or present at 0.1 wt% to 5 wt% of the total electrolyte weight, including all values ​​and ranges therein. In embodiments where the negative electrode comprises 20% or less (e.g., 0.1 wt% to 20 wt%) of silicon compounds of negative electrode 158, fluoroethylene carbonate (FEC) may be present at 1 wt% to 10 wt% (including all values ​​and ranges therein, e.g., 5 wt%) of the total electrolyte weight. In embodiments where the negative electrode comprises 21% or more (e.g., 21 wt% to 50 wt%) of silicon compounds of negative electrode 158, fluoroethylene carbonate (FEC) may be present at 11 wt% to 20 wt% (including all values ​​and ranges therein, e.g., 15 wt%) of the total electrolyte weight.

[0066] Co-additives, namely ethylene ethylene carbonate, 1,3,2-dioxazothiophene-2,2-dioxide (DTD), and fluoroethylene carbonate (FEC), have been found to contribute to the formation of a uniform, flexible, and adaptive solid electrolyte interface on the negative electrode (including silicon carbide) because they can counteract volume changes during charging and discharging. Lithium difluoro(oxalate)borate (LiDFOB) has been found to improve the uniformity and robustness of the positive electrode-electrolyte interface.

[0067] In some embodiments, electrolyte 162 comprises one or more of the following formulations. For battery cells formed at a temperature of up to 50°C and with a negative electrode comprising graphite and 10% by weight of a silicon compound, 0.9 M lithium hexafluorophosphate (LiPF6) and 0.3 M lithium bis(fluorosulfonyl)imide (LiFSI) are mixed in 30% by weight of ethylene carbonate (EC), 50% by weight of dimethyl carbonate (DMC), and 20% by weight of ethyl acetate (EA), together with 2.5% by weight of ethylene ethylene carbonate (VC), 0.5% by weight of 1,3,2-dioxazothiophene-2,2-dioxide, 0.5% by weight of lithium difluoro(oxalate)borate (LiDFOB), 5% by weight of fluoroethylene carbonate (FEC), and 5% by weight of fluorobenzene. For a battery cell formed at a temperature of 50°C to 80°C and comprising a negative electrode of graphite and 10 wt% silicon compound, 0.9 M lithium hexafluorophosphate (LiPF6) and 0.3 M lithium bis(fluorosulfonyl)imide (LiFSI) are mixed in ethylene carbonate (EC) present at 30 wt% of the total solvent volume and ethyl methyl carbonate (EMC) present at 70 wt% of the total solvent volume, along with ethylene ethylene carbonate (VC), 1,3,2-dioxazothiophene-2,2-dioxide (DTD), lithium difluoro(oxalate)borate (LiDFOB), fluoroethylene carbonate (FEC), and fluorobenzene at 5 wt% of the total electrolyte weight.

[0068] For battery cells formed at temperatures up to 50°C and with a graphite anode (pure graphite or modified artificial graphite), 0.9 M lithium hexafluorophosphate (LiPF6) and 0.3 M lithium bis(fluorosulfonyl)imide (LiFSI) are mixed in ethylene carbonate (EC) (30 vol% of the total solvent volume), dimethyl carbonate (DMC) (50 vol% of the total solvent volume), and ethyl acetate (EA) (20 vol% of the total solvent volume), along with ethylene ethylene carbonate (VC) (2.5 wt% of the total electrolyte weight), 1,3,2-dioxazothiophene-2,2-dioxide (DTD) (0.5 wt% of the total electrolyte weight), lithium difluoro(oxalate)borate (LiDFOB) (0.5 wt% of the total electrolyte weight), and fluorobenzene (5 wt% of the total electrolyte weight), wherein fluoroethylene carbonate (FEC) is omitted. For battery cells formed at temperatures between 50°C and 80°C with a graphite anode (pure graphite or modified artificial graphite), 0.9 M lithium hexafluorophosphate (LiPF6) and 0.3 M lithium bis(fluorosulfonyl)imide (LiFSI) are mixed in ethylene carbonate (EC) (30 vol% of the total solvent volume) and ethyl methyl carbonate (EMC) (70 vol% of the total solvent volume), along with ethylene ethylene carbonate (VC), 1,3,2-dioxazothiophene-2,2-dioxide (DTD), lithium difluoro(oxalate)borate (LiDFOB) (0.5 wt% of the total electrolyte volume), and fluorobenzene (5 wt% of the total electrolyte volume), wherein fluoroethylene carbonate (FEC) is omitted.

[0069] Electrolyte 162 is formed by mixing a carbonate solvent, a primary lithium salt, an optional secondary lithium salt, a phenyl additive including at least one fluorinated substituent, and co-additives. Electrolyte 162 can then be added to a battery cell (including...). Figures 2B to 2D In any of the battery cells 150 shown. Figure 3An embodiment of a method 300 for forming a battery cell 150 including an electrolyte 162 is shown. At block 302, a positive current collector 152 and a positive electrode 156, a negative current collector 154 and a negative electrode 158, and a separator 160 are assembled in a battery cell 150 including a cover 166 (including a cap 170 and a can 172). In some embodiments, the positive electrode 156 is deposited onto the positive current collector 152 prior to assembly of the battery cell 150, and the negative electrode 158 is deposited onto the negative current collector 154 prior to assembly of the battery cell 150. At block 304, the electrolyte 162 is added to the battery cell 150. At block 306, the battery cell 150 is sealed. In other embodiments, at block 308, the battery cell 150 is connected to a circuit and reformed. Battery formation occurs at a temperature below 50°C, for example in the range of 20°C to 50°C, or alternatively, at a high temperature of 51°C to 80°C. As described above, during battery formation, a solid electrolyte interface, such as lithium fluoride, is formed on the negative electrode, a positive electrolyte interface is formed, structural changes occur in the positive and negative electrode materials, and in some embodiments, the positive and negative electrode current collectors are corroded or dissolved.

[0070] Example

[0071] Two 2 amp-hour pouch cell units were constructed as described above. The first cell unit comprises a lithium iron phosphate positive electrode and a graphite negative electrode consisting of 100% pure graphite, loaded at a density of 3.3 mAh / cm². The second cell unit comprises a lithium iron phosphate positive electrode and a negative electrode consisting of 90% graphite and 10% silicon carbide, also loaded at a density of 3.3 mAh / cm².

[0072] In the graphite negative electrode bag, the electrolyte comprises: 0.9 M lithium hexafluorophosphate (LiPF6) and 0.3 M lithium bis(fluorosulfonyl)imide (LiFSI) mixed in a carbonate solvent of ethylene carbonate (EC) (30 vol% of total solvent volume), dimethyl carbonate (DMC) (50 vol% of total solvent volume), and ethyl acetate (EA) (20 vol% of total solvent volume), together with 2.5 wt% ethylene carbonate (VC), 0.5 wt% 1,3,2-dioxazothiophene-2,2-dioxide (DTD), 0.5 wt% lithium difluoro(oxalate)borate (LiDFOB), and 5 wt% fluorobenzene. The conductivity of the bag, measured at 25 °C, is 12.72 mSiemens / cm.

[0073] Figure 4The state of charge (percentage) is shown on the vertical y-axis relative to the horizontal x-axis, measured at 25°C over time (minutes). The voltage range is from 2.2V to 3.65V, with an applied compressive force of 69 kPa (10 psi). The battery cell exhibits a state of charge A from 0% to 80% in 11.45 minutes, demonstrating a 4.2C charging capability. Figure 5 The figure shows the relationship between the capacity retention (percentage) on the vertical y' axis and the coulombic efficiency (percentage) on the vertical y” axis as a function of the number of cycles. As shown, compared with the capacity retention A” and coulombic efficiency B” of the reference electrolyte without fluorobenzene, the electrolyte including fluorobenzene exhibits a relatively high capacity retention A’ (over 50 cycles) and a relatively small change in coulombic efficiency B’ (over 50 cycles). The reference electrolyte as mentioned herein comprises: 1.2 M lithium hexafluorophosphate (LiPF6) mixed in 30 vol% ethylene carbonate (EC) and 70 vol% methyl ethyl carbonate (EMC) of the total solvent volume, and 2 wt% ethylene ethylene carbonate (VC) of the total electrolyte weight.

[0074] In a bag with a silicon carbide-graphite anode, the electrolyte comprises: 0.9 M lithium hexafluorophosphate (LiPF6) and 0.3 M lithium bis(fluorosulfonyl)imide (LiFSI) mixed in 30 vol% ethylene carbonate (EC), 50 vol% dimethyl carbonate (DMC), and 20 vol% ethyl acetate (EA) by total solvent volume; which is combined with 2.5 wt% ethylene carbonate (VC), 0.5 wt% 1,3,2-dioxazothiophene-2,2-dioxide (DTD), 0.5 wt% lithium difluoro(oxalate)borate (LiDFOB), 5 wt% fluoroethylene carbonate (FEC), and 5 wt% fluorobenzene by total electrolyte volume. The conductivity measured at 25 °C is 12.32 mSiemens / cm. For a standard electrolyte that does not contain fluorobenzene, the typical conductivity is less than 8 millisiemens / cm.

[0075] Figure 6 The state of charge (percentage) is shown on the vertical y-axis relative to time (minutes) on the horizontal x-axis, measured at 25°C. The voltage range is 2.2V to 3.65V, and the compression is 69 kPa (10 psi). The battery cell exhibits a state of charge A from 0% to 80% in 8 minutes, demonstrating a 6C charging capability. Figure 7The figure shows the relationship between capacity retention (percentage) on the vertical y' axis and coulombic efficiency (percentage) on the vertical y” axis as a function of the number of cycles. As shown in the figure, the electrolyte including fluorobenzene exhibits a relatively high capacity retention of 94.6% A' (after 200 cycles) and charging efficiency B'.

[0076] The electrolyte, battery cell, secondary battery, and manufacturing method described herein offer numerous advantages. These advantages include, for example, a reduction in electrolyte viscosity of approximately 5% compared to a reference electrolyte without fluorobenzene additives. These advantages also include improved interfacial wettability between the electrolyte and the lithium iron phosphate cathode. Furthermore, these advantages include the formation of a solid electrolyte interface with the negative electrode. These advantages further include the formation of an ultrafast 6C rechargeable battery. Additionally, compared to a reference electrolyte without additives, these advantages include improved capacity retention and charging efficiency.

[0077] As used herein, the term "controller" and related terms such as microcontroller, control module, module, control, control unit, processor, and similar terms refer to one or more combinations of application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), electronic circuits, central processing units (e.g., microprocessors), and related non-transient memory components in the form of memory and storage devices (read-only, programmable read-only, random access, hard disk drives, etc.). Controller 132 may also consist of multiple controllers electrically connected to each other. Controller 132 may interconnect with additional systems and / or controllers of vehicle 100, thereby allowing controller 132 to access data, such as the speed, acceleration, braking, and steering angle of vehicle 100.

[0078] The processor may be a custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among a plurality of processors associated with controller 132, a semi-composite conductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally a device for executing instructions.

[0079] The tangible non-transitory memory 134 may include volatile and non-volatile storage devices such as read-only memory (ROM), random access memory (RAM), and keep-alive memory (KAM). KAM is persistent or non-volatile memory that can be used to store various operational variables when the processor is powered off. The tangible non-transitory memory 134 may be implemented using multiple storage devices such as PROM (programmable read-only memory), EPROM (electrical PROM), EEPROM (electrically erasable PROM), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which represent executable instructions used by the controller 132 to control various systems of the vehicle 100.

[0080] The descriptions in this disclosure are merely exemplary in nature, and variations thereof that do not depart from the spirit and scope of this disclosure are intended to fall within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. An electrolyte for a battery cell, the electrolyte comprising: Carbonate solvent; A primary lithium salt, comprising lithium hexafluorophosphate, wherein the primary lithium salt is present in the solvent at a concentration of 0.6 M to 2.0 M; An optional secondary lithium salt is present in the solvent at a concentration of 0.1 M to 0.5 M, wherein if the secondary lithium salt is present, the total concentration of the primary lithium salt and the secondary lithium salt is at most 2.0 M; A phenyl additive, said phenyl additive comprising at least one of fluorinated substituents and fluorinated substituents, said phenyl additive being present in an amount of 0.5% to 20% by weight of the total weight of the electrolyte; and The co-additive is present at 0.1% to 20% by weight of the total weight of the electrolyte, wherein the remaining weight percentage includes the carbonate solvent, the primary lithium salt, and the secondary lithium salt, and the total weight of the electrolyte is 100% by weight.

2. The electrolyte according to claim 1, wherein, The lithium salt is lithium bis(fluorosulfonyl)imide.

3. The electrolyte according to claim 1, wherein, The carbonate solvent comprises a mixture of ethylene carbonate present in 20 to 40 vol% of the solvent and a linear carbonate present in 60 to 80 vol% of the solvent, wherein the total volume percentage of the solvent is 100%.

4. The electrolyte according to claim 3, wherein, Ethyl acetate is present in the solvent at a volume percentage of 1 to 20 vol%, wherein the total volume percentage of the solvent is 100%.

5. The electrolyte according to claim 3, wherein, The linear carbonate includes at least one of ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate.

6. The electrolyte according to claim 1, wherein, The phenyl additive is fluorobenzene.

7. The electrolyte according to claim 1, wherein, The phenyl additive has the following formula: Among them, R 1 R 2 R 3 R 4 R 5 and R 6 At least one of them is fluorine, a fluorinated alkyl group having 1 to 10 carbons, and a fluorinated alkoxy group having 1 to 10 carbons, if R is present. 1 R 2 R 3 R 4 R 5 R 6 The remainder, R 1 R 2 R 3 R 4 R 5 R 6 The remaining portion is independently selected from hydrogen, halogens other than fluorine, alkyl groups having 1 to 10 carbons, methoxy groups, vinyl groups, propargyl groups, alkynyl groups having 1 to 10 carbons, benzyl groups, hydroxyl groups, alkoxy groups having 1 to 10 carbons, alkenyloxy groups having 1 to 10 carbons, alkynyloxy groups having 1 to 10 carbons, aryloxy groups having 1 to 10 carbons, heterocyclic alkoxy groups having 1 to 10 carbons and up to 2 rings, heterocyclic alkoxy groups having 1 to 10 carbons, oxo groups, carboxyl groups, ester groups, and ether groups.

8. The electrolyte according to claim 7, wherein, R 1 R 2 R 3 R 4 R 5 R 6 At least one of them is C n H x F y CH2C n H x F y CH2OC n H x F y and CF2OC n H x F y Where n is in the range of 1 to 5, x is in the range of 0 to 11, and y is in the range of 1 to 11.

9. The electrolyte according to claim 1, wherein, The co-additives include at least one of vinylene carbonate, 1,3,2-dioxazothiophene-2,2-dioxide, lithium difluoro(oxalate)borate, and fluoroethylene carbonate.

10. A method for forming an electrolyte, including: The electrolyte comprises a mixed carbonate solvent, a primary lithium salt, an optional secondary lithium salt, a phenyl additive, and a co-additive; the primary lithium salt comprises lithium hexafluorophosphate, which is present in the solvent at a concentration of 0.6 M to 2.0 M; when the secondary lithium salt is present, it is present in the solvent at an amount of 0.1 M to 0.5 M, wherein the total concentration of the primary lithium salt and the secondary lithium salt is 2.0 M; the phenyl additive comprises at least one of fluorinated substituents and fluorinated substituents, which is present at a concentration of 0.5 wt% to 20 wt% of the total weight of the electrolyte; the co-additive is present at a concentration of 0.1 wt% to 20 wt% of the total weight of the electrolyte, wherein the remaining weight percentage is the carbonate solvent, the primary lithium salt, and the secondary lithium salt, and the total weight of the electrolyte is 100 wt%.

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