Electrolyte for electrochemical cells with silicon-containing electrodes

Abstract

The present application relates to electrolytes for electrochemical cells having silicon-containing electrodes. Provided herein are electrolyte compositions for electrochemical cells including silicon-containing electrodes and electrochemical cells comprising the electrolyte compositions. The electrolyte compositions comprise a lithium salt, fluoroethylenecarbonate (FEC), a linear carbonate, vinylene carbonate, and a fluorosilane additive. The FEC and linear carbonate are present in the electrolyte composition in a ratio of about 1:3 v / v to about 1:9 v / v.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to electrolyte compositions for electrochemical cells having silicon-containing electrodes and electrochemical cells comprising the electrolyte compositions. BACKGROUND

[0002] This section provides background information relating to the present disclosure and is not necessarily prior art.

[0003] High energy density electrochemical cells, such as lithium ion batteries, can be used in a variety of consumer products and vehicles, such as hybrid electric vehicles (HEV) and electric vehicles (EV). A typical lithium ion battery includes a first electrode (e.g., a cathode), a second electrode of opposite polarity (e.g., an anode), an electrolyte material, and a separator. Conventional lithium ion batteries operate by reversibly transporting lithium ions between the negative and positive electrodes. A separator and electrolyte are disposed between the negative and positive electrodes. The electrolyte is adapted to conduct lithium ions and can be in solid, semi-solid, or liquid form. Lithium ions move from the cathode (positive electrode) to the anode (negative electrode) during charging of the battery and in the opposite direction during discharging of the battery. For convenience, the negative electrode will be used synonymously with the anode, although as recognized by those skilled in the art, the anode function can be associated with the positive electrode rather than the negative electrode during certain stages of the lithium ion cycle (e.g., the negative electrode can be the anode during discharge and the cathode during charge).

[0004] In various aspects, the electrodes comprise an electroactive material. The negative electrode typically comprises an electroactive material capable of acting as a lithium host material that serves as the negative terminal for the lithium ion battery. Conventional negative electrodes comprise the electroactive lithium host material and, optionally, another electrically conductive material, such as carbon black particles, and one or more polymeric binder materials to hold the lithium host material and conductive particles together.

[0005] Typical electroactive materials used to form negative electrodes (e.g., anodes) in lithium-ion electrochemical cells include lithium-graphite intercalation compounds, lithium-silicon alloys, lithium-tin compounds, and other lithium alloys. Although graphite compounds are most common, there is increasing interest in anode materials with high specific capacity (as compared to conventional graphite). For example, silicon has one of the highest known theoretical lithium capacities, making it one of the most attractive alternatives to graphite as a negative electrode material for rechargeable lithium-ion batteries. However, current silicon anode materials have serious drawbacks. For example, silicon-containing materials undergo large volume changes (e.g., volume expansion / contraction) during lithium intercalation / deintercalation (e.g., intercalation and deintercalation). In addition, the initial lithiation process of silicon-based electroactive materials can promote an increase in surface roughness. Furthermore, additional volume changes can occur during successive charge and discharge cycles of the silicon electroactive material. Such volume changes can result in fatigue cracking and bursting of the electroactive material. This can potentially lead to loss of electrical contact between the silicon-containing electroactive material and the rest of the battery cell and consumption of electrolyte to form a new solid electrolyte interface (SEI), resulting in reduced electrochemical cycling performance, reduced coulombic charge capacity retention (capacity fade), and limited cycle life.

[0006] In addition, during cycling of silicon-containing electrochemical cells with electrolytes containing fluoroethylene carbonate (FEC), gases can be generated. These gases can cause safety issues and reduce the cycle life of silicon-containing electrochemical cells, particularly soft pack cells.

[0007] It is desirable to develop electrolytes for electrochemical cells, particularly including electrodes containing silicon, for use in high energy and high power lithium-ion batteries that overcome current drawbacks that hinder their widespread commercial use. Thus, it is desirable to develop electrolytes for use in electrochemical cells having electrodes containing silicon or other electroactive materials that undergo significant volume changes during lithium-ion cycling that are capable of minimizing gas generation and minimizing capacity fade and maximizing charge capacity in commercial lithium-ion batteries with long life. For long-term and efficient use, high specific capacity electrode materials, such as silicon, should be capable of minimizing capacity fade and maximizing charge capacity for long-term use in lithium-ion batteries. SUMMARY

[0008] This section provides a general summary of the disclosure, and not a comprehensive disclosure of its full scope or all of its features.

[0009] In certain aspects, the present disclosure provides an electrolyte composition for an electrochemical cell. The electrolyte composition includes a lithium salt, fluoroethylene carbonate (FEC), a linear carbonate, vinylene carbonate, and a fluorosilane additive. The FEC and the linear carbonate can be present in a ratio of about 1 :3 v / v to about 1 :9 v / v. The fluorosilane additive corresponds in structure to Formula I:

[0010]

[0011] (I),

[0012] where R can be a polar aprotic group and x can be 1-20.

[0013] The FEC can be present in an amount of about 10 wt% to about 30 wt% and the vinylene carbonate can be present in an amount of about 50 wt% to about 80 wt% based on the total weight of the electrolyte composition.

[0014] The fluorosilane additive and the vinylene carbonate can each be present in an amount of about 1 wt% to about 5 wt% based on the total weight of the electrolyte composition.

[0015] The lithium salt can be selected from 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 difluoro(oxalato)borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), and combinations thereof.

[0016] The linear carbonate can be selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof.

[0017] In Formula (I), R can be selected from a nitrile, a methoxy group, a methyl methacrylate, a methyl methanesulfinate, a methyl formamide, an acetyl group, and an acetoxy group; and x can be 1-5.

[0018] The fluoro-silane additive can be selected from the group consisting of (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

[0019] In the electrolyte composition, ethylene carbonate (EC) can be absent.

[0020] In yet other aspects, the present disclosure provides an electrochemical cell. The electrochemical cell includes a negative electrode comprising a first electroactive material comprising silicon and a positive electrode comprising a second electroactive material. The positive electrode can be spaced apart from the negative electrode and a porous separator can be disposed between opposing surfaces of the negative electrode and the positive electrode. The electrochemical cell further comprises an electrolyte that permeates one or more of the negative electrode, the positive electrode, and the porous separator. The liquid electrolyte comprises a lithium salt, fluoroethylene carbonate (FEC), a linear carbonate, vinylene carbonate, and a fluoro-silane additive. The FEC and the linear carbonate can be present in a ratio of about 1 :3 v / v to about 1 :9 v / v. The fluoro-silane additive corresponds in structure to Formula I:

[0021]

[0022] (I),

[0023] where R can be a polar aprotic group and x can be 1-20.

[0024] The first electroactive material comprises silicon-containing particles having an average particle diameter greater than or equal to about 1 pm. The silicon-containing particles can include silicon, carbon-coated silicon, silicon oxide, lithium-silicon alloy, silicon-tin alloy, silicon-iron alloy, silicon-aluminum alloy, silicon-cobalt alloy, or combinations thereof.

[0025] The FEC can be present in an amount of about 10 wt% to about 30 wt% and the vinylene carbonate is present in an amount of about 50 wt% to about 80 wt% based on the total weight of the electrolyte.

[0026] The fluoro-silane additive and the vinylene carbonate can each be present in an amount of about 1 wt% to about 5 wt% based on the total weight of the electrolyte.

[0027] The lithium salt can be selected from 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 difluoro(oxalato)borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), and combinations thereof.

[0028] The linear carbonate can be selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof.

[0029] In formula (I), R can be selected from nitrile, methoxy, methyl methacrylate, methyl methysulfoxide, methyl formamide, acetyl, and acetoxy; and x can be 1-5.

[0030] The fluorosilane additive can be selected from (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

[0031] In the electrolyte, ethylene carbonate (EC) can be absent.

[0032] The negative electrode can further comprise a conductive material, wherein the conductive material comprises carbon black, acetylene black, graphite, carbon nanotubes, carbon fibers, carbon nanofibers, graphene, graphene nanoplatelets, graphene oxide, nitrogen-doped carbon, metal powders, liquid metals, conductive polymers, or combinations thereof.

[0033] The second electroactive material can be selected from Li (1+x) Mn2O4, wherein 0.1 < x < 1; LiMn (2-x) Ni x O4, wherein 0 < x < 0.5; LiCoO2; Li(Ni x Mn y Co z )O2, wherein 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1; LiNi (1-x-y) Co x M yO2, where 0 < x < 0.2, y < 0.2, and M is Al, Mg, or Ti; LiFePO4, LiMn 2-x Fe x PO4, where 0 < x < 0.3; LiNiCoAlO2; LiMPO4, where M is at least one of Fe, Ni, Co, and Mn; Li(Ni x Mn y Co z Al p )O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < p < 1, x + y + z + p = 1 (NCMA); LiNiMnCoO2; Li2FePO4F; LiMn2O4; LiFeSiO4; LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622), LiMnO2 (LMO), activated carbon, sulfur, and combinations thereof.

[0034] The electrochemical cell can be a soft pack cell.

[0035] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0036] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0037] Figure 1 is a schematic diagram of an exemplary electrochemical cell;

[0038] Figure 2 is a schematic diagram of an exemplary battery pack;

[0039] Figure 3 is a graph depicting the discharge charge capacity (Ahr) versus cycle number for comparative soft pack cell A and soft pack cell 1 formed according to Example 1;

[0040] Figure 4 is a graph depicting the discharge charge capacity (Ahr) versus cycle number for soft pack cells 2-4 formed according to Example 1;

[0041] Figure 5A and 5B is a photographic image of soft pack cell 2 after cycling;

[0042] Figure 5C and 5D is a photographic image of the soft-pack battery 3 after cycling;

[0043] Figure 6 is a graph depicting discharge charge capacity (Ahr) versus cycle number for comparative soft-pack battery B formed according to Example 2;

[0044] Corresponding reference characters indicate corresponding parts throughout the drawings. DETAILED DESCRIPTION

[0045] Example embodiments will now be more fully described with reference to the accompanying drawings.

[0046] Example embodiments are provided so as to enable this disclosure to be thorough and to convey the full scope to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific compositions, ingredients, devices, and methods, in order to provide a thorough understanding of embodiments of the present disclosure. Those skilled in the relevant arts will recognize that number of specific details are not required to practice embodiments of the present disclosure. Whatever specific details are required will be dependent on the particular implementation and are purely for illustration and descriptive purposes. In some example embodiments, well-known methods, structures and techniques are not described in detail.

[0047] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, integers, compositions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, compositions, steps, operations, elements, components, and / or groups thereof. Although the open term "comprising," as typically employed in the art, is understood to be a non-limiting term specific for describing various embodiments described herein, in certain aspects, the term, in contrast, is alternatively understood to be a more limiting and restrictive term such as "consisting of' or "consisting essentially of." Thus, with respect to any given embodiment reciting a composition, a material, a component, an element, a feature, an integer, an operation, and / or a process step, the disclosure also specifically includes embodiments where such recited composition, material, component, element, feature, integer, operation, and / or process step is "consisting of' or "consisting essentially of' only those elements as specifically enumerated. In the case of "consisting of," alternative embodiments are ruled out where any additional composition, material, component, element, feature, integer, operation, and / or process step is present. In the case of "consisting essentially of," alternative embodiments are ruled out where any additional composition, material, component, element, feature, integer, operation, and / or process step is present, which materially affects the basic and novel characteristic(s) of the embodiments.

[0048] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps can be employed, unless otherwise specifically noted.

[0049] When a component, element, or layer is referred to as being "on," "engaged," "connected," "attached," or "coupled" to another component, element, or layer, it can be directly on, engaged, connected, attached, or coupled to the other component, element, or layer, or intervening components, elements, or layers can be present. In contrast, when an element is referred to as being "directly on," "directly engaged," "directly connected," "directly attached," or "directly coupled" to another element or layer, there are no intervening components, elements, or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (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.

[0050] Although the terms first, second, third, etc. can be used herein to describe various steps, elements, components, regions, layers and / or sections, these steps, elements, components, regions, layers and / or sections should not be limited by these terms, unless otherwise indicated. The first, second, third, etc. terms can be used herein to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Unless the context clearly indicates otherwise, the terms such as "first," "second," and the other numerical terms as used herein do not denote any order or sequence, but rather are used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.

[0051] For ease of description, spatial or temporal terms, such as "front," "back," "inner," "outer," "under," "below," "lower," "above," "upper," and the like, can be used herein for describing the orientation of one element or feature relative to another element or feature, as illustrated in the figures. The spatial or temporal terms can be intended to include different orientations of the device or system in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "below" or "under" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can include both the orientations above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

[0052] The term "alkyl" (alone or in combination with another term(s)) means a saturated hydrocarbon chain containing from 1 to about 25 carbon atoms, such as but not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, and the like. The alkyl group can be straight-chain or branched. "Alkyl" is intended to include all structural isomers of alkyl. For example, as used herein, propyl includes n-propyl and i-propyl; butyl includes n-butyl, sec-butyl, i-butyl, and t-butyl; pentyl includes n-pentyl, t-pentyl, neopentyl, i-pentyl, sec-pentyl, and 3-pentyl. In addition, as used herein, "Me" means methyl, "Et" means ethyl, "Pr" means propyl, "i-Pr" means isopropyl, "Bu" means butyl, "t-Bu" means t-butyl, and "Np" means neopentyl. In some embodiments, the alkyl group is a C1-C5-, C1-C4-, C1-C3-, or C1-C2-alkyl group.

[0053] The term "alkoxy" refers to -O-alkyl groups containing from one to about eight carbon atoms. Alkoxy groups can be straight or branched. Non-limiting examples include methoxy, ethoxy, propyloxy, butyloxy, isobutyloxy, t-butyloxy, pentyloxy, and hexyloxy. In some embodiments, alkoxy is C1-C5-, C1-C4-, C1-C3-, or C1-C2-alkoxy.

[0054] It should be understood that any reference to a method, composition, apparatus or system "comprising" certain steps, components or features means that the method, composition, apparatus or system can "consist essentially of" the steps, components or features listed, such that any additional steps, components or features that do not substantially affect the basic and novel characteristics of the application are excluded.

[0055] Throughout this disclosure, numerical values represent approximate measures or range limits to include slight deviations and embodiments generally having the listed values and embodiments exactly having the listed values. Except in the Examples provided at the end of the DETAILED DESCRIPTION section, all numerical values in this specification (including the appended claims) that are by nature relative to a parameter (e.g., amount or condition) should be understood to be modified by the term "about," whether expressly appearing in the value or not. "About" means that the stated numerical value allows for a certain degree of imprecision (some close to the value; approximately or reasonably close to the value; nearly). If the imprecision provided by "about" is not understood in the art, then "about" as used herein at least means an acceptable variation that can occur due to the ordinary methods of measuring and using such parameters. For example, "about" can include a variation 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 certain aspects, optionally less than or equal to 0.1%.

[0056] Furthermore, the disclosure of a range includes all values and further subdivisions between the endpoints and the subranges included in the range.

[0057] Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0058] I. Silicon-containing electrochemical cells

[0059] The present disclosure relates to improved electrolyte compositions for electrochemical cells, such as lithium ion batteries, and electrochemical cells comprising the improved electrolyte compositions. In lithium ion electrochemical cells or batteries, the negative electrode typically comprises a lithium intercalation material or alloy host material. As discussed above, conventional electroactive materials for forming the negative electrode or anode include lithium-graphite intercalation compounds, lithium-silicon alloys, lithium-tin compounds, and other lithium alloys. Although graphite compounds are the most commonly used, there is increasing interest in certain anode materials having high specific capacity (as compared to conventional graphite). Due to the high theoretical capacity of silicon (Si), silicon oxide, and tin, they are attractive alternatives to graphite as anode materials for rechargeable lithium ion batteries. However, silicon-containing materials can undergo large volume changes (e.g., volume expansion / contraction) during lithium intercalation / deintercalation (e.g., intercalation and deintercalation), which can lead to fatigue cracking and bursting of the electroactive material. In addition, during cycling of silicon-containing electrochemical cells with electrolytes comprising fluoroethylenecarbonate (FEC), gases such as carbon dioxide (CO2) and carbon monoxide (CO) can be generated. These gases can cause safety issues and reduce the cycle life of silicon-containing electrochemical cells, particularly soft-pack batteries. These challenges have been an obstacle to their widespread use in lithium ion batteries. Accordingly, there is a need for improved electrolyte compositions for silicon-containing electrochemical cells.

[0060] Lithium-containing electrochemical cells typically include a negative electrode, a positive electrode, an electrolyte for conducting lithium ions between the negative and positive electrodes, and a porous separator between the negative and positive electrodes to physically separate and electrically insulate the electrodes from each other while allowing free ion flow. When assembled in an electrochemical cell, such as in a lithium ion battery, the porous separator is permeated with a liquid electrolyte. It has been discovered that electrolyte compositions comprising fluoroethylenecarbonate (FEC), a linear carbonate such as dimethyl carbonate (DMC), and a fluorosilane additive can advantageously produce a minimum amount of gassing and result in improved electrochemical cell cycle life when introduced into an electrochemical cell comprising a silicon-containing negative electrode.

[0061] Provided herein is an electrochemical cell for use in a battery, such as a lithium ion battery, or as a capacitor. For example, one exemplary and schematic illustration of an electrochemical cell (also referred to as a lithium ion battery or battery) 20 is shown in FIG. 1. The electrochemical cell 20 includes a negative electrode 22, a positive electrode 24, and a porous separator 26 between the negative and positive electrodes 22, 24. The negative electrode 22 includes a silicon-containing material, such as silicon, silicon alloy, or silicon oxide. The positive electrode 24 includes a lithium-containing material, such as lithium metal, lithium alloy, or lithium intercalation compound. The porous separator 26 is permeated with an electrolyte composition 28 comprising fluoroethylenecarbonate (FEC), a linear carbonate such as dimethyl carbonate (DMC), and a fluorosilane additive. Figure 1The electrochemical cell 20 includes a negative electrode 22 (also referred to as a negative electrode layer 22), a positive electrode 24 (also referred to as a positive electrode layer 24), and a separator 26 (e.g., a microporous polymeric separator) disposed between the two electrodes 22, 24. The space between the negative electrode 22 and the positive electrode 24 (e.g., the separator 26) can be filled with an electrolyte 30. If there are pores within the negative electrode 22 and the positive electrode 24, those pores can also be filled with the electrolyte 30. The electrolyte 30 can impregnate, permeate, or wet the surface of each of the negative electrode 22, the positive electrode 24, and the porous separator 26 and fill the pores of each of them. A negative electrode current collector 32 can be disposed at or near the negative electrode 22, and a positive electrode current collector 34 can be disposed at or near the positive electrode 24. The negative electrode current collector 32 and the positive electrode current collector 34 collect and deliver free electrons from and to an external circuit 40, respectively. An interruptible external circuit 40 and a load device 42 are connected to the negative electrode 22 (through its current collector 32) and the positive electrode 24 (through its current collector 34). The negative electrode 22, the positive electrode 24, and the separator 26 can each further contain the electrolyte 30, which is capable of conducting lithium ions. The separator 26 acts as both an electrical insulator and a mechanical support by being sandwiched between the negative electrode 22 and the positive electrode 24 to prevent physical contact and thus prevent a short from occurring. The separator 26 can also provide a minimum resistance path for the internal travel of lithium ions (and associated anions) to facilitate the operation of the battery 20, in addition to providing a physical barrier between the two electrodes 22, 24. The separator 26 also contains the electrolyte solution in the open network of pores during the lithium ion cycling to facilitate the operation of the battery 20.

[0062] When the negative electrode 22 contains a relatively greater amount of intercalated lithium, the battery 20 can generate an electric current during discharge by the reversible electrochemical reactions that occur when the external circuit 40 is closed (to connect the negative electrode 22 and the positive electrode 24). The chemical potential difference between the positive electrode 24 and the negative electrode 22 drives the electrons produced by the oxidation of the intercalated lithium at the negative electrode 22 to flow to the positive electrode 24 via the external circuit 40. Lithium ions produced at the negative electrode are simultaneously transported to the positive electrode 24 via the electrolyte 30 and the separator 26. The flow of electrons through the external circuit 40 and the migration of lithium ions through the separator 26 in the electrolyte 30 to form intercalated lithium at the positive electrode 24 can be controlled and directed through the load device 42 until the intercalated lithium in the negative electrode 22 is depleted and the capacity of the lithium ion battery 20 is reduced.

[0063] The lithium-ion battery 20 can be recharged or re-energized at any time by connecting an external power source to the lithium-ion battery 20 to reverse the electrochemical reactions that occur during battery discharge. Connection of the external power source to the lithium-ion battery 20 causes the otherwise non-spontaneous oxidation of intercalated lithium at the positive electrode 24 to produce electrons and lithium ions. The electrons that flow back to the negative electrode 22 via the external circuit 40 and the lithium ions carried by the electrolyte 30 through the separator 26 back to the negative electrode 22 recombine at the negative electrode 22 and replenish the intercalated lithium for it to be consumed during the next battery discharge event. In this way, one complete discharge event followed by one complete charge event is considered a cycle, with the lithium ions being cycled between the positive electrode 24 and the negative electrode 22. The external power source that can be used to charge the lithium-ion battery 20 can vary with the size, construction, and particular end use of the lithium-ion battery 20. Some notable and exemplary external power sources include, but are not limited to, an AC wall outlet and a motor vehicle alternator.

[0064] In many battery constructions, the negative electrode current collector 32, the negative electrode 22, the separator 26, the positive electrode 24, and the positive electrode current collector 34 are each fabricated as relatively thin layers (e.g., a few microns or 1 millimeter or less in thickness) and assembled as a set of layers connected in electrical parallel arrangement to provide a suitable energy package. The negative electrode current collector 32 and the positive electrode current collector 34 each collect and deliver free electrons from and to the external circuit 40.

[0065] In addition, the battery 20 can include various other components known to those skilled in the art although not depicted herein. For example, as non-limiting examples, the lithium-ion battery 20 can include a housing, gaskets, end caps, tabs, battery terminals, and any other conventional components or materials that can be located within the battery 20, including between or adjacent to the negative electrode 22, the positive electrode 24, and / or the separator 26. Figure 1 The battery 20 shown in FIG. 1 includes a liquid electrolyte 30 and illustrates a representative concept of battery operation.

[0066] As noted above, the size and shape of the lithium-ion battery 20 can vary depending on the particular application for which it is designed. Battery-powered vehicles and hand-held consumer electronics devices, for example, are two examples in which the battery 20 would most likely be designed to different size, capacity, and power output specifications. The battery 20 can also be connected in series or parallel with other similar lithium-ion batteries or batteries if needed by the load device 42 to produce greater voltage output and power density.

[0067] Accordingly, the battery 20 can generate electrical current to a load device 42 operatively connected to the external circuit 40. The load device 42 can be powered in whole or in part by the electrical current passing through the external circuit 40 as the lithium-ion battery 20 discharges. Although the load device 42 can be any number of known electrically powered devices, as non-limiting examples, several specific examples of electrically consuming load devices include electric motors of hybrid or all-electric vehicles, notebook computers, tablet computers, mobile phones, and cordless power tools or appliances. The load device 42 can also be a power generation device that charges the battery 20 for storage of energy.

[0068] The present technology relates to improved electrochemical cells, particularly lithium-ion batteries. In various instances, such batteries are used in vehicular or automotive transportation applications (e.g., motorcycles, boats, tractors, buses, motorcycles, mobile homes, campers, and tanks). However, the present technology can be used in a wide variety of other industries and applications, including, by way of non-limiting examples, aerospace components, consumer goods, instruments, buildings (e.g., houses, offices, sheds, and warehouses), office equipment and furniture, and industrial equipment machinery, agricultural or farm equipment, or heavy machinery.

[0069] A. Electrolyte

[0070] Referring again to Figure 1 The positive electrode 24, the negative electrode 22, and the separator 26 each contain an electrolyte composition or system 30 (electrolyte 30) within their pores, which is capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24. The electrolyte composition 30 is provided herein in a liquid or gel form, which is capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24, and can be used in the battery 20. In certain aspects, the electrolyte composition 30 can be a non-aqueous liquid electrolyte solution containing a lithium salt dissolved in an organic solvent or mixture of organic solvents. In any embodiment, the electrolyte 30 contains a lithium salt, fluoroethylene carbonate (FEC), a linear carbonate, vinylene carbonate, and a fluorosilane additive.

[0071] For example, a non-limiting list of lithium salts that can be dissolved in an organic solvent to form a non-aqueous liquid electrolyte solution includes 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 difluoro(oxalato)borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), and combinations thereof. The lithium salt can be present in the electrolyte composition in an amount greater than or equal to about 0.5 mol / L, greater than or equal to about 0.8 mol / L, greater than or equal to about 1 mol / L, greater than or equal to about 1.2 mol / L, greater than or equal to about 1.4 mol / L, greater than or equal to about 1.5 mol / L, greater than or equal to about 1.7 mol / L, or about 2 mol / L; from about 0.5 mol / L to about 2 mol / L, from about 0.8 mol / L to about 1.7 mol / L, or from about 0.8 mol / L to about 1.5 mol / L.

[0072] In addition to the FEC, the electrolyte composition 30 can also include a variety of non-aqueous, aprotic organic solvents, such as linear carbonates. Examples of linear carbonates include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof. In any embodiment, the FEC and / or linear carbonate can be present in the electrolyte 30 in an amount that minimizes outgassing that can occur during cycling of the electrochemical cell. For example, the FEC can be present in the electrolyte 30 in an amount greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, greater than or equal to about 40 wt%, or about 50 wt%; or from about 5 wt% to about 50 wt%, from about 5 wt% to about 30 wt%, from about 10 wt% to about 30 wt%, or from about 10 wt% to about 25 wt%, based on the total weight of the electrolyte. The linear carbonate can be present in the electrolyte 30 in an amount greater than or equal to about 40 wt%, greater than or equal to about 50 wt%, greater than or equal to about 60 wt%, greater than or equal to about 70 wt%, greater than or equal to about 75 wt%, or about 80 wt%; or from about 40 wt% to about 80 wt%, from about 50 wt% to about 80 wt%, or from about 50 wt% to about 75 wt%, based on the total weight of the electrolyte.

[0073] Additionally or alternatively, the FEC and linear carbonate can be present in the electrolyte composition in a volume ratio of about 1 :2 v / v, about 1 :3 v / v, about 1 :4 v / v, about 1 :5 v / v, about 1 :6 v / v, about 1 :7 v / v, about 1 :8 v / v, about 1 :9 v / v, or about 1 :10 v / v; or about 1 :2 v / v to about 1 :10 v / v, about 1 :3 v / v to about 1 :9 v / v, about 1 :2 v / v to about 1 :6 v / v, or about 1 :3 v / v to about 1 :5 v / v. For example, the FEC can be present in a mixture of FEC and linear carbonate in an amount greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, or about 40 wt%; about 5 wt% to about 40 wt%, about 5 wt% to about 30 wt%, about 10 wt% to about 30 wt%, or about 10 wt% to about 25 wt%, based on the total weight of the mixture. The remainder of the mixture of FEC and linear carbonate can be linear carbonate, for example, present in an amount of about 60 wt% to about 95 wt%, about 70 wt% to about 95 wt%, or about 75 wt% to about 90 wt%, based on the total amount of the mixture.

[0074] Optionally, the electrolyte composition 30 can include one or more different types of alkyl carbonates such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC)), aliphatic carboxylic acid esters (e.g., methyl formate, methyl acetate, methyl propionate), gamma-lactones (e.g., gamma-butyrolactone, gamma-valerolactone), chain structure ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran), 1,3-dioxolane), sulfur compounds (e.g., sulfolane), and combinations thereof. Alternatively, the electrolyte composition 30 can include substantially no any further alkyl carbonates described above. For example, the electrolyte composition 30 can include no EC.

[0075] In any embodiment, the fluoroalkylsilane additive corresponds in structure to Formula I:

[0076]

[0077] (I)

[0078] where R can be a polar aprotic group and x can be 1-20. In various aspects, x can be 1-15, 3-10, 1-5, or 1-4. Examples of polar aprotic groups include, but are not limited to, ester, oxide, ether, tertiary amine, alkoxy, ketone, aldehyde, carbonate, nitrile, nitro, sulfoxide, acetyl, acrylate, and phosphine. For example, R can be selected from the group consisting of nitrile (-CN) (also referred to as "cyano"), alkoxy (e.g., methoxy, ethoxy, propoxy), alkyl methacrylate (e.g., methyl methacrylate), alkyl sulfoxide (e.g., methyl sulfoxide (-SOCH3)), alkyl carboxamide (e.g., methyl carboxamide), acetyl (-COH3), and acetoxy (-OCOCH3) (also referred to as "acetyloxy"). In some embodiments, R can be selected from the group consisting of nitrile, methoxy, methyl methacrylate, methyl sulfoxide, methyl carboxamide, acetyl, and acetoxy. In any embodiment, the fluoroalkylsilane additive can be selected from the group consisting of (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

[0079] In any embodiment, the fluoroalkylsilane additive and the vinylene carbonate can each be present in the electrolyte 30 in an amount greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, greater than or equal to about 3 wt%, greater than or equal to about 4 wt%, greater than or equal to about 5 wt%, greater than or equal to about 6 wt%, greater than or equal to about 7 wt%, or about 10 wt%; or from about 1 wt% to about 10 wt%, from about 1 wt% to about 7 wt%, from about 1 wt% to about 5 wt%, or from about 1 wt% to about 3 wt%, based on the total weight of the electrolyte.

[0080] The electrolyte composition can be prepared by mixing the FEC and the linear carbonate in the above amounts to form a mixture. The above lithium salt can be added and dissolved into the FEC and linear carbonate mixture, followed by the addition of the vinylene carbonate and the fluoroalkylsilane additive in the above amounts to form the electrolyte composition. The addition of the components of the electrolyte composition and the mixing can be performed in a climate-controlled environment at room temperature (e.g., 18°C to 25°C).

[0081] B. Isolator

[0082] Separator 26 can include, for example, a microporous polymeric separator comprising a polyolefin. The polyolefin can be a homopolymer (derived from a single monomer component) or a heteropolymer (derived from more than one monomer component), which can be linear or branched. If the heteropolymer is derived from two monomer components, the polyolefin can exhibit any copolymer chain arrangement, including those of block copolymers or random copolymers. Similarly, if the polyolefin is a heteropolymer derived from more than two monomer components, it can likewise be a block copolymer or a random copolymer. In certain aspects, the polyolefin can be a polyethylene (PE), a polypropylene (PP), or a blend of PE and PP, or a multi-layer structured porous film of PE and / or PP. Commercially available polyolefin porous separator films include CELGARD ® 2500 (single layer polypropylene separator) and CELGARD ® 2325 (three layer polypropylene / polyethylene / polypropylene separator).

[0083] In certain aspects, separator 26 can further include one or more of a ceramic coating and a heat resistant material coating. The ceramic coating and / or heat resistant material coating can be disposed on one or more sides of separator 26. The material forming the ceramic layer can be selected from the group consisting of aluminum oxide (AI2O3), silicon dioxide (SiO2), and combinations thereof. The heat resistant material can be selected from the group consisting of Nomex, Aramid, and combinations thereof.

[0084] When the separator 26 is a microporous polymeric separator, it can be a single layer or a multi-layer laminate, which can be manufactured by dry or wet processes. For example, in some cases, a single layer of a polyolefin can form the entire separator 26. In other aspects, the separator 26 can be a fibrous membrane having a large number of pores extending between opposing surfaces and can have, for example, an average thickness of less than 1 millimeter. However, as another example, multiple individual layers of the same or different polyolefins can be assembled to form the microporous polymeric separator 26. In addition to the polyolefins, the separator 26 can also include other polymers such as, but not limited to, polyethylene terephthalate (PET), polyvinylidene fluoride (PVdF), polyamides, polyimides, poly(amide-imide) copolymers, polyetherimides, and / or cellulose, or any other material suitable for producing the desired porous structure. The polyolefin layers and any other optional polymer layers can further be included in the separator 26 as fibrous layers to help provide the separator 26 with the appropriate structural and porosity characteristics. In some aspects, the separator 26 can also be mixed with or coated on its surface with a ceramic material. For example, the ceramic coating can include aluminum oxide (AI2O3), silicon dioxide (SiO2), titanium dioxide (TiO2), or combinations thereof. Various conventionally available polymers and commercial products for forming the separator 26 are contemplated, as well as a number of manufacturing methods that can be used to produce such microporous polymeric separators 26.

[0085] C. Negative Electrode

[0086] The negative electrode 22 includes a first electroactive material that includes a lithium host material capable of acting as a negative terminal for a lithium-ion battery. In any embodiment, the first electroactive material includes a silicon-containing material. In various aspects, the first electroactive material can consist solely of a silicon-containing material, i.e., the first electroactive material can be 100% silicon-containing material. The silicon-containing electroactive material can include silicon, carbon-coated silicon, silicon oxide, lithium silicon alloys, silicon tin alloys, silicon iron alloys, silicon aluminum alloys, silicon cobalt alloys, or combinations thereof. Examples of silicon-containing alloys, such as binary and ternary alloys, include, but are not limited to, Si-Sn, SiSnFe, SiSnAl, SiFeCo, etc. In certain embodiments, the silicon-containing electroactive material includes or consists essentially of silicon in a crystalline or amorphous structure, rather than alloys of silicon. Carbon-coated silicon particles and methods of forming such particles are described in U.S. Patent Application Serial No. 16 / 668,882, which is incorporated herein by reference in its entirety. For example, the silicon-containing particles can include a continuous interlayer comprising carbide disposed on a surface of a silicon-containing particle and a continuous carbon coating disposed adjacent to the continuous interlayer. The continuous carbon coating can be a multi-layer carbon coating including an inner first layer containing amorphous carbon disposed adjacent to the continuous interlayer and an outer second layer containing graphitic carbon. In some embodiments, the first electroactive material can be pre-lithiated by techniques known in the art.

[0087] The silicon-containing electroactive material can have a round geometry or an axial geometry and thus can be in the form of a particle, or in alternative variations, can be in the form of a thin film, nanowire, nanorod, nanospring, or hollow tube. In particular, the silicon-containing electroactive material is present as a silicon-containing particle. The silicon-containing electroactive material structure, e.g., silicon structure, can be nanoscale or microscale, preferably microscale. Such silicon structures can help accommodate the large volume changes that occur in silicon during lithium cycling in lithium-ion batteries. The term "axial geometry" refers to particles that generally have a rod, fiber, or other cylindrical shape, which has a distinct long axis or elongated axis. Generally, the aspect ratio (AR) of a cylindrical shape, e.g., fiber or rod, is defined as AR = L / D, where L is the length of the longest axis and D is the diameter of the cylinder or fiber. Exemplary axial geometry electroactive material particles suitable for use in the present disclosure can have a high aspect ratio, e.g., from about 10 to about 5,000. In certain variations, the first electroactive material particles having an axial geometry include fibers, wires, flakes, whiskers, filaments, tubes, rods, and the like.

[0088] The term "round geometry" generally applies to particles that have a lower aspect ratio, e.g., an aspect ratio that is close to 1 (e.g., less than 10). It should be noted that the particle geometry can differ from a true round shape, and can include, for example, an elliptical or oval shape, including oblate spheroids or flattened spheroids, agglomerated particles, polygonal (e.g., hexagonal) particles, or other shapes that generally have a low aspect ratio. The flattened spheroids can have a disc-like shape with a relatively high aspect ratio. Thus, the generally round geometry particles are not limited to a relatively low aspect ratio and a spherical shape. For the silicon-containing electroactive material particles, a suitable silicon-containing particle can have an average particle size diameter that is greater than or equal to about 10 nm, greater than or equal to about 100 nm, greater than or equal to about 1 μm, greater than or equal to about 2 μm, greater than or equal to about 5 μm, greater than or equal to about 8 μm, greater than or equal to about 10 μm, greater than or equal to about 12.5 μm, greater than or equal to about 15 μm, greater than or equal to about 17.5 μm, greater than or equal to about 20 μm, or about 25 μm; or from about 10 nm to about 25 μm, from about 100 nm to about 20 μm, from about 1 μm to about 20 μm, from about 1 μm to about 15 μm, from about 1 μm to about 10 μm, or from about 2 μm to about 8 μm.

[0089] In addition, the negative electrode 22 can include a conductive material and a polymeric binder. Examples of the conductive material include, but are not limited to, carbon black, graphite, acetylene black (e.g., KETCHEN TM black or DENKA TMcarbon nanotubes, carbon fibers, carbon nanofibers, graphene, graphene nanosheets, graphene oxide, nitrogen-doped carbon, metal powders (e.g., copper, nickel, steel), liquid metals (e.g., Ga, GaInSn), conductive polymers (e.g., including polyaniline, polythiophene, polyacetylene, polypyrrole, and the like), and combinations thereof. Such conductive materials in particulate form can have a circular geometry or an axial geometry as described above.

[0090] As used herein, the term "graphene nanosheet" refers to a nanoplatelet or stack of graphene layers. In one particular embodiment, the conductive material comprises graphene nanosheets and optionally one or more of the other conductive materials listed above. In various aspects, the graphene nanosheets have an average particle diameter or lateral dimension greater than or equal to about 100 nm, greater than or equal to about 1 µm, greater than or equal to about 5 µm, greater than or equal to about 10 µm, greater than or equal to about 15 µm, greater than or equal to about 20 µm, greater than or equal to about 25 µm, or about 30 µm; or from about 100 nm to about 30 µm, from about 1 µm to about 25 µm, from about 5 µm to about 25 µm, or from about 10 µm to about 20 µm. Additionally or alternatively, the graphene nanosheets can have a thickness less than or equal to about 250 nm, less than or equal to about 100 nm, less than or equal to about 50 nm, less than or equal to about 25 nm, less than or equal to about 10 nm, less than or equal to about 5 nm, or about 1 nm; or from about 1 nm to about 250 nm, from about 1 nm to about 100 nm, from about 1 nm to about 50 nm, from about 1 nm to about 10 nm, or from about 1 nm to about 5 nm. Additionally or alternatively, the conductive material (e.g., graphene nanosheets) can have a surface area greater than or equal to about 25 m2 / g, greater than or equal to about 50 m2 / g, greater than or equal to about 100 m2 / g, greater than or equal to about 250 m2 / g, greater than or equal to about 500 m2 / g, greater than or equal to about 750 m2 / g, or about 1000 m2 / g; from about 25 m2 / g to about 75 m2 / g, from about 50 m2 / g to about 100 m2 / g, from about 100 m2 / g to about 250 m2 / g, from about 250 m2 / g to about 500 m2 / g, from about 500 m2 / g to about 750 m2 / g, or from about 750 m2 / g to about 1000 m2 / g. 2 / g, greater than or equal to about 50 m 2 / g, greater than or equal to about 100 m 2 / g, greater than or equal to about 250 m 2 / g, greater than or equal to about 500 m 2 / g, or about 750 m 2 / g; from about 25 m 2 / g to about 75 m 2 / g, about 50 m 2 / g to about 100 m 2 / g, about 25 m 2 / g to about 750 m 2 / g, about 250 m 2 / g to about 750 m 2 / g, or about 500 m 2 / g to about 750 m 2 / g.

[0091] As used herein, the term "polymer binder" includes polymer precursors used to form a polymer binder, such as a monomer or monomer system that can form any of the polymer binders disclosed above. Examples of suitable polymer binders include, but are not limited to, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, or carboxymethylcellulose (CMC), nitrile rubber (NBR), styrene butadiene rubber (SBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), poly(acrylic acid) PAA, polyimide, polyamide, sodium alginate, lithium alginate, and combinations thereof. In some embodiments, the polymer binder can be a non-aqueous solvent-based polymer or an aqueous-based polymer. In particular, the polymer binder can be a non-aqueous solvent-based polymer that can exhibit lower capacity fade, provide a more robust mechanical network and improved mechanical properties to more effectively cope with silicon particle swelling, and have good chemical and thermal resistance. For example, the polymer binder can include polyimide, polyamide, polyacrylonitrile, polyacrylic acid, salts of polyacrylic acid (e.g., potassium, sodium, lithium), polyacrylamide, polyvinyl alcohol, carboxymethylcellulose, or combinations thereof. The first electroactive material can be admixed with the electrically conductive material and at least one polymer binder. The polymer binder can serve multiple roles in the electrode, including: (i) enabling electronic and ionic conductivity of the composite electrode, (ii) providing electrode integrity, such as integrity of the electrode and its components, and adhesion to the current collector, and (iii) participating in the formation of the important solid electrolyte interface (SEI) as the kinetics of lithium intercalation is largely determined by the SEI.

[0092] In all aspects, the first electroactive material may be present in the negative electrode in an amount greater than or equal to about 50 wt%, greater than or equal to about 60 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, greater than or equal to about 95 wt%, or about 98 wt%; or about 50 wt% to about 98 wt%, about 60 wt% to about 95 wt%, about 60 wt% to about 95 wt%, or about 60 wt% to about 80 wt% based on the total weight of the negative electrode. Additionally or alternatively, the conductive material may be present in the negative electrode in an amount greater than or equal to about 0.2 wt%, greater than or equal to about 1 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, or about 25 wt%; or about 0.2 wt% to about 25 wt%, about 1 wt% to about 25 wt%, about 2 wt% to about 20 wt%, about 5 wt% to about 15 wt%, or about 2 wt% to about 10 wt% based on the total weight of the negative electrode. Additionally or alternatively, the polymeric adhesive may be present in the negative electrode in an amount greater than or equal to about 0.5 wt%, greater than or equal to about 1 wt%, greater than or equal to about 3 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, or about 30 wt%; or about 0.5 wt% to about 30 wt%, about 1 wt% to about 25 wt%, about 3 wt% to about 20 wt%, or about 5 wt% to about 15 wt%.

[0093] D. Positive electrode

[0094] The positive electrode 24 may be formed of a second electroactive material capable of sufficient lithium insertion and extraction while serving as the positive terminal of the lithium-ion battery pack 20. The positive electrode 24 may also include a polymer binder material to structurally reinforce the lithium-based active and conductive materials. An exemplary common type of known material that can be used to form the positive electrode 24 is a layered lithium transition metal oxide. For example, in some embodiments, the positive electrode 24 may contain Li... (1+x) Mn₂O₄, where 0.1 ≤ x ≤ 1; LiMn (2-x) Ni x O4, where 0 ≤ x ≤ 0.5; LiCoO2; Li(Ni x Mn y Co z O2, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1 and x + y + z = 1; LiNi (1-x-y) Co x M yO2, where 0 < x < 0.2, y < 0.2 and M is Al, Mg or Ti; LiFePO4, LiMn 2-x Fe x PO4, where 0 < x < 0.3; LiNiCoAlO2; LiMPO4, where M is at least one of Fe, Ni, Co and Mn; Li(Ni x Mn y Co z Al p )O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < p < 1, x + y + z + p = 1 (NCMA); LiNiMnCoO2; Li2FePO4F; LiMn2O4; LiFeSiO4; LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622), LiMnO2(LMO), activated carbon, sulfur (e.g., greater than 60 wt% based on the total weight of the positive electrode) or combinations thereof.

[0095] In certain variations, the second electroactive material can be admixed with an electronically conductive material described herein that provides an electron conduction path and / or at least one polymeric binder material described herein that improves the structural integrity of the electrode. For example, the first electroactive material and the electronically conductive or conductive material can be slurry cast together with such a binder, such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, or carboxymethylcellulose (CMC), nitrile rubber (NBR), styrene butadiene rubber (SBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), poly(acrylic acid) PAA, polyimide, polyamide, sodium alginate, or lithium alginate.

[0096] E. Current Collector

[0097] The positive electrode current collector 34 can be formed of aluminum (Al) or any other suitable electrically conductive material known to those skilled in the art. The negative electrode current collector 32 can include a metal (including copper, nickel or alloys thereof, stainless steel) or other suitable electrically conductive material known to those skilled in the art. In certain aspects, the positive electrode current collector 34 and / or the negative electrode current collector 32 can be in the form of a foil, a slit mesh, and / or a woven mesh.

[0098] Referring now to Figure 2 , the electrochemical cell 20 (as shown in Figure 1 ) can be combined with one or more other electrochemical cells to produce a lithium ion battery 400. Figure 2The lithium-ion battery pack 400 shown in FIG. 1 includes a plurality of rectangular-shaped electrochemical cells 410. Any number of 5 to 150 electrochemical cells 410 can be stacked side-by-side in a module configuration and connected in series or parallel to form a lithium-ion battery pack 400, such as for use in a vehicle powertrain. The lithium-ion battery pack 400 can be further connected in series or parallel to other similarly configured lithium-ion battery packs to form a lithium-ion battery pack pack that exhibits the voltage and current capacity required for a particular application, such as a vehicle. It should be appreciated that, Figure 2 The lithium-ion battery pack 400 shown in FIG. 1 is merely illustrative and is not intended to convey the relative size of any of the components of the electrochemical cells 410 or to limit the wide variety of structural configurations that the lithium-ion battery pack 400 can take. Although explicitly shown, it is possible for the lithium-ion battery pack 400 to include more or fewer electrochemical cells 410 than shown in FIG. 1. Figure 2 Various structural modifications to the lithium-ion battery pack 400 shown in FIG. 1 are possible.

[0099] Each electrochemical cell 410 includes a negative electrode 412, a positive electrode 414, and a separator 416 positioned between the two electrodes 412, 414. Each of the negative electrode 412, the positive electrode 414, and the separator 416 is impregnated, infiltrated, or wetted with a liquid electrolyte (e.g., electrolyte 30) capable of transporting lithium ions. A negative electrode current collector 420, including negative polarity tabs 444, is positioned between the negative electrodes 412 of adjacent electrochemical cells 410. Similarly, a positive electrode current collector 422, including positive polarity tabs 446, is positioned between adjacent positive electrodes 424. The negative polarity tabs 444 are electrically coupled to a negative terminal 448, and the positive polarity tabs 446 are electrically coupled to a positive terminal 450. An applied compressive force typically presses the current collectors 420, 422 against the electrodes 412, 414 and the electrodes 412, 414 against the separators 416 to achieve intimate interfacial contact between the several contact components of each electrochemical cell 410.

[0100] The battery pack 400 can include more than two pairs of positive and negative electrodes 412, 414. In one form, the battery pack 400 can include 15-60 pairs of positive and negative electrodes 412, 414. Additionally, although Figure 2 The battery pack 400 shown in FIG. 1 is constructed from a plurality of individual electrodes 412, 414 and separators 416, although other arrangements are of course possible. For example, instead of individual separators 416, the positive and negative electrodes 412, 414 can be separated from one another by wrapping or interlacing a single continuous separator sheet between the positive and negative electrodes 412, 414. In another example, the battery pack 400 can include continuous and sequentially stacked sheets of positive electrodes, separators, and negative electrodes that are folded or rolled together to form a "jelly roll."

[0101] The negative and positive terminals 448, 450 of the lithium-ion battery pack 400 are connected to an electrical device 452 that is part of an interruptible circuit 454 established between the negative electrodes 412 and the positive electrodes 414 of the many electrochemical cells 410. The electrical device 452 can include an electrical load or a power generation device. An electrical load is an electrical consuming device that is powered, in whole or in part, by the lithium-ion battery pack 400. Conversely, a power generation device is a device that charges or re-energizes the lithium-ion battery pack 400 by an applied external voltage. In some cases, the electrical load and the power generation device can be the same device. For example, the electrical device 452 can be an electric motor for a hybrid electric vehicle or a range-extended electric vehicle that is designed to draw current from the lithium-ion battery pack 400 during acceleration and to provide regenerative current to the lithium-ion battery pack 400 during deceleration. The electrical load and the power generation device can also be different devices. For example, the electrical load can be an electric motor for a hybrid electric vehicle or a range-extended electric vehicle, and the power generation device can be an AC wall outlet, an internal combustion engine, and / or a vehicle alternator.

[0102] The lithium-ion battery pack 400 can provide useful current to the electrical device 452 through the reversible electrochemical reactions that occur in the electrochemical cells 410 when the negative electrodes 412 contain sufficient amounts of intercalated lithium (i.e., during discharge) when the interruptible circuit 454 is closed to connect the negative terminal 448 and the positive terminal 450. When the negative electrodes 412 are depleted of intercalated lithium and the capacity of the electrochemical cells 410 is exhausted, the lithium-ion battery pack 400 can be charged or re-energized by applying an external voltage from the electrical device 452 to the electrochemical cells 410 to reverse the electrochemical reactions that occurred during discharge.

[0103] Although not shown in the drawings, the lithium-ion battery pack 400 can include a wide variety of other components. For example, the lithium-ion battery pack 400 can include a housing, gaskets, end caps, and any other desired components or materials that can be located between or around the electrochemical cells 410 for performance-related or other practical purposes. For example, the lithium-ion battery pack 400 can be packaged within a housing (not shown). The housing can comprise a metal, such as aluminum or steel, or the housing can comprise a film pouch material having multiple laminated layers.

[0104] The formed electrochemical cells 20, 400 considered herein can be a soft-pack cell, a button cell, or another all-electrochemical cell having a cylindrical form or a wound square form. In the square form, the electrodes and current collectors form a stacked geometry that can be sealed with a packaging material capable of preventing air and water contamination of the cell 20, 400. In the cylindrical form, the multi-layer structure can be wound into a construction similar to a jelly-roll. After addition of the electrolyte 30, the wound structure can be sealed in a metal container. In a soft-pack cell, conductive foil tabs (tabs 444, 446) can be welded to the electrodes and led to the outside in a fully sealed manner, rather than using a metal cylinder and glass-metal electrical feedthrough. The soft-pack material can include one or more layers of a suitable polymer, such as a lithium-containing polymer. Examples

[0105] General information

[0106] Unless otherwise noted, silicon particles were used as the electroactive material in the anode in the cells formed in the following examples.

[0107] Unless otherwise noted below, each soft-pack cell prepared in the following examples consisted of 6 layers of cathode (LiNi 0.6 Mn 0.2 Co 0.2 O2) and 7 layers of anode, as further described below, with Celgard® 2325 as the separator and encapsulated in a polymer soft-pack (D-EL408PH(3) film from Dai Nippon Printing Co., Ltd.).

[0108] Unless otherwise noted below, each soft-pack cell prepared in the following examples was tested as follows: 2 formation cycles at C / 20 and C / 5 cycles at 25°C. The cell was charged to 4.2 V and held at 4.2 V until the current decayed to C / 50. The cell was then discharged to 3.0 V. The rest time between charge and discharge was 30 minutes.

[0109] Example 1

[0110] Comparative soft-pack cell A and soft-pack cell 1 each included a cathode and a separator as described above, with an anode consisting of silicon, a polyimide binder, and carbon black. Soft-pack cells 2-4 each included a cathode and a separator as described above, with an anode consisting of silicon, a polyimide binder, and graphene nanoplatelets. The electrolyte compositions included in comparative soft-pack cell A and soft-pack cells 1-4 are shown in Table 1 below.

[0111] Table 1

[0112] Pouch cell Electrolyte composition Comparison A 10 wt% FEC in 1 M LiPF6 EC / DMC / EMC (1:1:1 V / V / V) 1 1.2 M LiPF6in FEC:DMC (1 :3, V / V) with vinylene carbonate (2 wt%) and (3-cyanopropyl)dimethylfluorosilane (3 wt%) 2 1.2 M LiPF6in FEC:DMC (1 :3, V / V) with vinylene carbonate (2 wt%) and (3-cyanopropyl)dimethylfluorosilane (3 wt%) 3 1.2 M LiPF6in FEC:DMC (1 :4, V / V) with vinylene carbonate (2 wt%) and (3-cyanopropyl)dimethylfluorosilane (3 wt%) 4 1.2 M LiPF6in FEC:DMC (1 :9, V / V) with vinylene carbonate (2 wt%) and (3-cyanopropyl)dimethylfluorosilane (3 wt%)

[0113] Cycling was performed on Comparative pouch cell A and pouch cells 1-4 as described above. The results are shown in Figure 3 and 4 In Figure 3 , the x-axis (310) is cycle number, while for Comparative cell A (340) and pouch cell 1 (350), the discharge charge capacity (Ahr) is shown on the left y-axis (320). In Figure 4 , the x-axis (410) is cycle number, while for pouch cell 2 (430), pouch cell 4 (440), and pouch cell 3 (450), the discharge charge capacity (Ahr) is shown on the left y-axis (420). As shown in Figure 4 , 80% capacity retention was achieved for pouch cell 2 up to 118 cycles, for pouch cell 3 up to 178 cycles, and for pouch cell 4 up to 166 cycles. Figure 5A and 5B is a photographic image of pouch cell 2 after cycling, showing the gas produced (10 ml of gas produced). Figure 5C and 5D is a photographic image of pouch cell 3 after cycling, showing the gas produced (0.95 ml of gas produced).

[0114] Example 2

[0115] Comparative pouch cell B included a cathode and separator as described above, and an anode composed of silicon, polyimide binder, and carbon black. The electrolyte composition included in Comparative pouch cell B is shown in Table 2 below.

[0116] Table 2

[0117] Pouch cell Electrolyte composition Comparison B 1.2 M LiPF6in FEC:EMC (1 :4, V / V) with vinylene carbonate (2 wt%) and (3-cyanopropyl)dimethylfluorosilane (3 wt%)

[0118] Cycling was performed on Comparative pouch cell B as described above. The results are shown in Figure 6 In Figure 6 , the x-axis (610) is cycle number, while for Comparative pouch cell B, the discharge charge capacity (Ahr) is shown on the left y-axis (620).

[0119] The foregoing description of implementations has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Individual elements or features of a particular implementation are generally not limited to that particular implementation, but, where applicable, are interchangeable and can be used in a selected implementation, even if not specifically shown or described. The same can hold true for described manufacturing, and / or assembly methods. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

[0120] The present application can include the following technical solutions.

[0121] 1. An electrolyte composition for an electrochemical cell, the electrolyte composition comprising:

[0122] a lithium salt;

[0123] fluoroethylenecarbonate (FEC);

[0124] a linear carbonate, wherein the FEC and the linear carbonate are present in a ratio of about 1 :3 v / v to about 1 :9 v / v;

[0125] vinylene carbonate; and

[0126] a fluorosilane additive corresponding in structure to Formula I:

[0127] (I),

[0128] wherein R is a polar aprotic group and x is 1-20.

[0129] 2. The electrolyte composition according to Scheme 1, wherein the FEC is present in an amount of about 10 wt% to about 30 wt% based on the total weight of the electrolyte composition and the vinylene carbonate is present in an amount of about 50 wt% to about 80 wt% based on the total weight of the electrolyte composition.

[0130] 3. The electrolyte composition according to Scheme 1, wherein the fluorosilane additive and the vinylene carbonate are each present in an amount of about 1 wt% to about 5 wt% based on the total weight of the electrolyte composition.

[0131] 4. The electrolyte composition according to Scheme 1, wherein the lithium salt is selected from the group consisting of 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 difluoro(oxalato)borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), and combinations thereof.

[0132] 5. The electrolyte composition according to Scheme 1, wherein the linear carbonate is selected from the group consisting of dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), and combinations thereof.

[0133] 6. The electrolyte composition according to Scheme 1, wherein R is selected from the group consisting of nitrile, methoxy, methyl methacrylate, methyl methysulfoxide, methyl formamide, acetyl, and acetoxy; and x is 1-5.

[0134] 7. The electrolyte composition according to Scheme 1, wherein the fluorosilane additive is selected from the group consisting of (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

[0135] 8. The electrolyte composition according to Scheme 1, wherein ethylene carbonate (EC) is not present.

[0136] 9. An electrochemical cell, comprising:

[0137] a negative electrode comprising a first electroactive material comprising silicon;

[0138] a positive electrode comprising a second electroactive material, wherein the positive electrode is spaced apart from the negative electrode;

[0139] a porous separator disposed between opposing surfaces of the negative electrode and the positive electrode; and

[0140] an electrolyte permeating one or more of: the negative electrode, the positive electrode, and the porous separator,

[0141] wherein the liquid electrolyte comprises:

[0142] a lithium salt;

[0143] fluorinated ethylene carbonate (FEC);

[0144] a linear carbonate, wherein the FEC and the linear carbonate are present in a ratio of about 1 :3 v / v to about 1 :9 v / v;

[0145] vinylene carbonate; and

[0146] a fluorosilane additive corresponding in structure to Formula I:

[0147] (I),

[0148] wherein R is a polar aprotic group and x is 1-20.

[0149] 10. The electrochemical cell according to Scheme 9, wherein the first electroactive material comprises silicon-containing particles having an average particle diameter greater than or equal to about 1 pm, wherein the silicon-containing particles comprise silicon, carbon-coated silicon, silicon oxide, lithium silicon alloy, silicon tin alloy, silicon iron alloy, silicon aluminum alloy, silicon cobalt alloy, or combinations thereof.

[0150] 11. The electrochemical cell according to Scheme 9, wherein the FEC is present in an amount of about 10 wt% to about 30 wt% based on the total weight of the electrolyte and the vinylene carbonate is present in an amount of about 50 wt% to about 80 wt% based on the total weight of the electrolyte.

[0151] 12. The electrochemical cell according to Scheme 9, wherein the fluoro-silane additive and the vinylene carbonate are each present in an amount of about 1 wt% to about 5 wt% based on the total weight of the electrolyte.

[0152] 13. The electrochemical cell according to Scheme 9, wherein the lithium salt is selected from the group consisting of 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 difluoro(oxalato)borate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium triflate (LiCF3SO3), lithium bis(trifluoromethane)sulfonimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI), and combinations thereof.

[0153] 14. The electrochemical cell according to Scheme 9, wherein the linear carbonate is selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and combinations thereof.

[0154] 15. The electrochemical cell according to Scheme 9, wherein R is selected from the group consisting of nitrile, methoxy, methyl methacrylate, methylsulfoxide, methylformamide, acetyl, and acetoxy; and x is 1-5.

[0155] 16. The electrochemical cell according to Scheme 9, wherein the fluoro-silane additive is selected from the group consisting of (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

[0156] 17. The electrochemical cell according to Scheme 9, wherein ethylene carbonate (EC) is not present in the electrolyte.

[0157] 18. The electrochemical cell according to aspect 9, wherein the negative electrode further comprises a conductive material, and the conductive material includes carbon black, acetylene black, graphite, carbon nanotubes, carbon fibers, carbon nanofibers, graphene, graphene nanosheets, graphene oxide, nitrogen-doped carbon, metal powder, liquid metal, conductive polymer, or a combination thereof.

[0158] 19. The electrochemical cell according to aspect 9, wherein the second electroactive material is selected from the group consisting of Li (1+x) Mn2O4, where 0.1 ≤ x ≤ 1; LiMn (2-x) Ni x O4, where 0 ≤ x ≤ 0.5; LiCoO2; Li(Ni x Mn y Co z )O2, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, and x + y + z = 1; LiNi (1-x-y) Co x M y O2, where 0 < x < 0.2, y < 0.2, and M is Al, Mg, or Ti; LiFePO4, LiMn 2-x Fe x PO4, where 0 < x < 0.3; LiNiCoAlO2; LiMPO4, where M is at least one of Fe, Ni, Co, and Mn; Li(Ni x Mn y Co z Al p )O2, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ P ≤ 1, x + y + z + p = 1 (NCMA); LiNiMnCoO2; Li2FePO4F; LiMn2O4; LiFeSiO4; LiNi 0.6 Mn<从 0.2 Co 0.2 O2 (NMC622), LiMnO2 (LMO), activated carbon, sulfur, and combinations thereof.

[0159] 20. The electrochemical cell according to aspect 9, wherein the electrochemical cell is a pouch cell.

Claims

1. An electrolyte composition for an electrochemical cell, the electrolyte composition comprising: a lithium salt; fluoro-substituted ethylene carbonate; a linear carbonate, wherein the fluoro-substituted ethylene carbonate and the linear carbonate are present in a ratio of 1 :3 v / v to 1 :9 v / v; vinylene carbonate; and a fluorosilane additive corresponding in structure to Formula I: wherein R is a polar aprotic group and x is 1-20; wherein the electrochemical cell includes a negative electrode comprising a first electroactive material comprising silicon.

2. The electrolyte composition of claim 1, wherein the fluoro-substituted ethylene carbonate is present in an amount of 10 wt% to 30 wt% based on the total weight of the electrolyte composition, and the linear carbonate is present in an amount of 50 wt% to 80 wt% based on the total weight of the electrolyte composition.

3. The electrolyte composition of claim 1, wherein the fluorosilane additive and the vinylene carbonate are each present in an amount of 1 wt% to 5 wt% based on the total weight of the electrolyte composition.

4. The electrolyte composition of claim 1, wherein the lithium salt is selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium tetrachloroaluminate, lithium iodide, lithium bromide, lithium thiocyanate, lithium tetrafluoroborate, lithium tetraphenylborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium hexafluoroarsenate, lithium triflate, lithium bis(trifluoromethane)sulfonimide, lithium bis(fluorosulfonyl)imide, and combinations thereof.

5. The electrolyte composition of claim 1, wherein the linear carbonate is selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and combinations thereof.

6. The electrolyte composition of claim 1, wherein R is selected from the group consisting of a nitrile, a methoxy group, a methyl methacrylate, a methyl methylsulfoxide, a methyl formamide, an acetyl group, and an acetoxy group; and x is 1-5.

7. The electrolyte composition of claim 1, wherein the fluorosilane additive is selected from the group consisting of (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

8. The electrolyte composition of claim 1, wherein no vinylene carbonate is present.

9. An electrochemical cell comprising: a negative electrode comprising a first electroactive material comprising silicon; a positive electrode comprising a second electroactive material, wherein the positive electrode is spaced apart from the negative electrode; a porous separator disposed between opposing surfaces of the negative electrode and the positive electrode; and an electrolyte permeating one or more of: the negative electrode, the positive electrode, and the porous separator, wherein the electrolyte comprises: a lithium salt; fluoro-substituted ethylene carbonate; a linear carbonate, wherein the fluoro-substituted ethylene carbonate and the linear carbonate are present in a ratio of 1 :3 v / v to 1 :9 v / v; vinylene carbonate; and a fluorosilane additive corresponding in structure to Formula I: wherein R is a polar aprotic group and x is 1-20. ​ 10. The electrochemical cell of claim 9, wherein the first electroactive material comprises silicon-containing particles having an average particle diameter greater than or equal to 1 pm, wherein the silicon-containing particles comprise silicon, carbon-coated silicon, silicon oxide, lithium silicon alloy, silicon tin alloy, silicon iron alloy, silicon aluminum alloy, silicon cobalt alloy, or a combination thereof.

11. The electrochemical cell of claim 9, wherein the vinylene carbonate is present in an amount of 10 to 30 weight percent based on the total weight of the electrolyte, and the linear carbonate is present in an amount of 50 to 80 weight percent based on the total weight of the electrolyte.

12. The electrochemical cell of claim 9, wherein the fluorosilane additive and the vinylene carbonate are each present in an amount of 1 to 5 weight percent based on the total weight of the electrolyte.

13. The electrochemical cell of claim 9, wherein the lithium salt is selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium tetrachloroaluminate, lithium iodide, lithium bromide, lithium thiocyanate, lithium tetrafluoroborate, lithium tetraphenylborate, lithium bis(oxalato)borate, lithium difluoro oxalato borate, lithium hexafluoroarsenate, lithium triflate, lithium bis(trifluoromethane)sulfonimide, lithium bis(fluorosulfonyl)imide, and combinations thereof.

14. The electrochemical cell of claim 9, wherein the linear carbonate is selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and combinations thereof.

15. The electrochemical cell of claim 9, wherein R is selected from the group consisting of nitrile, methoxy, methyl methacrylate, methyl methysulfoxide, methyl formamide, acetyl, and acetoxy; and x is 1-5.

16. The electrochemical cell of claim 9, wherein the fluorosilane additive is selected from the group consisting of (3-cyanopropyl)dimethylfluorosilane, (2-cyanoethyl)dimethylfluorosilane, (4-cyanobutyl)dimethylfluorosilane, and combinations thereof.

17. The electrochemical cell of claim 9, wherein vinylene carbonate is not present in the electrolyte.

18. The electrochemical cell of claim 9, the negative electrode further comprising a conductive material, wherein the conductive material comprises carbon black, graphite, carbon nanotubes, carbon fibers, graphene, graphene oxide, nitrogen-doped carbon, metal powder, liquid metal, conductive polymer, or combinations thereof.

19. The electrochemical cell of claim 9, the negative electrode further comprising a conductive material, wherein the conductive material comprises acetylene black, carbon nanofiber, graphene nanoplatelets, or combinations thereof.

20. The electrochemical cell of claim 9, wherein the second electroactive material is selected from the group consisting of Li (1+x) Mn2O4, wherein 0.1 < x < 1; LiMn (2-x) Ni x O4, wherein 0 < x < 0.5; and combinations thereof.

21. The electrochemical cell of claim 9, wherein the second electroactive material is selected from the group consisting of Li(Ni x Mn y Co z )O2, wherein 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1; LiMn 2-x Fe x PO4, wherein 0 < x < 0.3; and combinations thereof.

22. The electrochemical cell of claim 9, wherein the second electroactive material is selected from the group consisting of LiNi (1-x-y) Co x M y O2, wherein 0 < x < 0.2, y < 0.2, and M is Al, Mg, or Ti; LiMPO4, wherein M is at least one of Fe, Ni, Co, and Mn; and combinations thereof.

23. The electrochemical cell of claim 9, wherein the second electroactive material is selected from the group consisting of Li(Ni x Mn y Co z Al p )02, wherein 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < p < 1, x + y + z + p = 1; activated carbon, sulfur, and combinations thereof.

24. The electrochemical cell of claim 9, wherein the second electroactive material is selected from the group consisting of LiCoO2; LiFePO4, LiNiCoAlO2; LiNiMnCoO2; Li2FePO4F; LiMn2O4; LiFeSiO4; LiNi 0.6 Mn 0.2 Co 0.2 O2, LiMnO2, and combinations thereof.

25. The electrochemical cell of claim 9, wherein the electrochemical cell is a soft-packaged cell.

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