CARBONATE-BASED ELECTROLYTE SYSTEM FOR IMPROVING OR SUPPORTING THE EFFICIENCY OF ELECTROCHEMICAL CELLS WITH LITHIUM-CONTAINING ANODES

Abstract

Method for producing an electrolyte system that improves or increases the efficiency of an electrochemical cell, comprising a positive electrode comprising a positive lithium-based electroactive material and having a maximum potential greater than or equal to about 5 V, and a negative electrode comprising a negative electroactive material comprising lithium, the method comprising: Mixing one or more salts selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI) and combinations thereof, and a solvent comprising one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC) and combinations thereof, wherein a bound fraction with an ionization potential greater than an electron affinity is formed to create an electrolyte system that is substantially free of unbound dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC) and unbound bis(fluorosulfonyl)imide (FSI). - ) is, wherein one or more salts have a concentration in the electrolyte system of greater than or equal to approximately 4 M.

Description

INTRODUCTION

[0001] The following section provides background information on the present disclosure, which is not necessarily the prior art.

[0002] The present disclosure relates to the highly concentrated carbonate-based electrolyte system of an electrochemical cell with a high-energy cathode and a lithium-containing anode, as well as to methods for producing the highly concentrated electrolyte system and electrochemical cells including the highly concentrated electrolyte system. The electrolyte system comprises a bound component containing one or more salts associated with and / or bound to a carbonate-based solvent, wherein the one or more salts have a concentration in the electrolyte system of greater than or equal to approximately 4 M and a molar ratio of the one or more salts to the carbonate-based solvent is greater than or equal to approximately 0.5 to less than or equal to approximately 1. The bound component of the electrolyte system improves or enhances the efficiency of the electrochemical cell.

[0003] Against this background, high-energy-density electrochemical cells, such as lithium-ion and lithium-sulfur batteries, can be used in a wide variety of consumer products and vehicles, including hybrid electric vehicles (HEVs) and electric vehicles (EVs). Typical lithium-ion batteries comprise a primary electrode, a secondary electrode, an electrolyte, and a separator. One electrode serves as the positive electrode or cathode, and the other serves as the negative electrode or anode. A stack of lithium-ion battery cells can be electrically connected to increase overall power. Conventional rechargeable lithium-ion batteries operate by reversibly transferring lithium ions back and forth between the negative and positive electrodes. A separator and electrolyte are positioned between the negative and positive electrodes.The electrolyte is suitable for conducting lithium ions and can be in solid (e.g., solid-state diffusion) or liquid form. When the battery is charged, lithium ions move from a cathode (positive electrode) to an anode (negative electrode), and when the battery is discharged, they move in the opposite direction.

[0004] Many different materials can be used to manufacture components for a lithium-ion battery. As a non-limiting example, cathode materials for lithium-ion batteries typically include an electroactive material that can be intercalated or alloyed with lithium ions, such as lithium transition metal oxides or mixed oxides of the spinel type, for example, with spinel LiMn₂O₄, LiCoO₂, LiNiO₂, LiMn₂ 1,5 Ni 0,5 O4, LiNi( 1-x-y )Co x M yO2 (where 0 <x<1, y<1 und M Al, Mn oder dergleichen sein können), oder Lithiumeisenphosphate. Der Elektrolyt enthält typischerweise ein oder mehrere Lithiumsalze, die in einem nichtwässrigen Lösungsmittel gelöst und ionisiert sein können. Gebräuchliche negative Elektrodenmaterialien beinhalten Lithium-Insertionsmaterialien oder Legierungswirtsmaterialien, wie Lithium-Graphit-Interkalationsverbindungen oder Lithium-Silizium-Verbindungen, Lithium-Zinn-Legierungen und Lithium-Titanat Li 4+x Ti5O 12 , where 0 ≤ x ≤ 3, such as Li4Ti5O 12 (LTO).

[0005] The negative electrode can also consist of a lithium-containing material, such as metallic lithium, in which case the electrochemical cell is considered a lithium-metal battery or cell. Metallic lithium for use in the negative electrode of a rechargeable battery has several potential advantages, including the highest theoretical capacity and the lowest electrochemical potential. In this way, batteries with lithium-metal anodes can have a higher energy density, potentially doubling the storage capacity, so that while the battery is only half the size, it still has the same lifespan as other lithium-ion batteries. This makes lithium-metal batteries one of the most promising candidates for high-energy storage systems.However, lithium metal batteries also have potential disadvantages, including possibly unreliable or reduced performance and possible premature failure of electrochemical cells.

[0006] For example, side reactions can occur between the lithium metal and the species in the adjacent electrolyte located between the positive and negative electrodes. These reactions can promote power dissipation at the negative lithium electrodes, which can impair the coulombic efficiency and lifespan of rechargeable lithium batteries. Therefore, it would be desirable to develop materials for use in high-energy lithium-ion batteries that reduce or suppress lithium metal side reactions and thereby also suppress or minimize their resulting effects. SUMMARY

[0007] This part provides a general summary of the disclosure and is not a complete disclosure of the full scope of protection or all features.

[0008] In various aspects, the present disclosure provides a method for producing an electrolyte system that improves or increases the efficiency of an electrochemical cell. The electrochemical cell can include a positive electrode and a negative electrode. The positive electrode can consist of a positive lithium-based electroactive material and have a maximum potential greater than or equal to approximately 5 V. The negative electrode can include a negative electroactive material comprising lithium. The method can involve mixing one or more lamellae and a solvent to form a bonded component. The one or more salts can be selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof.The solvent can be selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and combinations thereof. The bound fraction can have an ionization potential greater than an electron affinity to form an electrolyte system that is essentially free of unbound dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and unbound bis(fluorosulfonyl)imide (FSI). - ) is. The one or more lamellae can have a concentration in the electrolyte system of greater than or equal to approximately 4M.

[0009] In one aspect, the solvent may contain dimethyl carbonate (DMC), and a molar ratio of one or more salts to dimethyl carbonate (DMC) may be approximately 0.5.

[0010] In one aspect, the solvent may contain dimethyl dicarbonate (DMDC), and the molar ratio of one or more salts to dimethyl dicarbonate (DMDC) may be approximately 1.

[0011] In one aspect, the electrolyte system can exhibit a dynamic viscosity of less than or equal to approximately 100 centipoise (cP).

[0012] In one aspect, the electrochemical cell can have an energy density of more than about 900 Wh / L.

[0013] In one aspect, the positive lithium-based electroactive material can contain elemental sulfur or a sulfur-containing active material.

[0014] In one aspect, the positive lithium-based electroactive material can be selected from the group consisting of nickel-manganese-cobalt 811 (NMC811), nickel-manganese-cobalt 622 (NMC622); lithium cobalt oxide (LiCoO2); lithium iron phosphate (LiFePO4); high-energy nickel-manganese-cobalt oxide (HENMC) (e.g., overlithed layered oxide cathode or lithium-rich NMC), lithium manganese-nickel oxide (LMNO); and combinations thereof.

[0015] In a further variation, the present disclosure provides another method for improving or optimizing the anodic stability of a lithium-cycling electrochemical cell. The method may involve introducing an electrolyte system into the electrochemical cell. The electrolyte system may contain a bound component. The bound component may have an ionization potential greater than an electron affinity. The bound component may comprise one or more salts bound to a solvent. The one or more salts may have a concentration in the electrolyte system of approximately 4 M or greater. The one or more salts may be selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof.The solvent may include one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and combinations thereof. The electrolyte system may be substantially free of unbound dimethyl carbonate (DMC), unbound dimethyl dicarbonate (DMDC), and unbound bis(fluorosulfonyl)imide (FSI). - ) be.

[0016] In one aspect, the electrochemical cell can include a positive electrode and a negative electrode. The positive electrode can contain a positive lithium-based electroactive material with a maximum potential greater than or equal to approximately 5V. The negative electrode can contain a negative electroactive material that includes lithium.

[0017] In one aspect, the solvent may contain dimethyl carbonate (DMC), and a molar ratio of one or more salts to dimethyl carbonate (DMC) may be approximately 0.5.

[0018] In one aspect, the solvent may contain dimethyl dicarbonate (DMDC), and the molar ratio of one or more salts to dimethyl dicarbonate (DMDC) may be approximately 1.

[0019] In one aspect, the electrolyte system can have a dynamic viscosity of less than or equal to about 100 centipoise (cP) and the electrochemical cell can have an energy density of more than about 900 Wh / L.

[0020] In a further variation, the present disclosure provides an electrochemical cell that cycles lithium ions with improved or optimized efficiency. The electrochemical cell may include a positive electrode, a separator, a negative electrode, and an electrolyte system. The positive electrode may have a positive lithium-based electroactive material and a maximum potential greater than or equal to approximately 5 V. The negative electrode may contain a negative electroactive material comprising lithium. The electrolyte system may include a bound component. The bound component may have an ionization potential greater than an electron affinity and may include one or more salts bound to a solvent.The one or more salts can be selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof. The solvent can include one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and combinations thereof. The one or more lamellae can have a concentration in the electrolyte system of approximately 4M or greater. The electrolyte system can be substantially free of unbound dimethyl carbonate (DMC), unbound dimethyl dicarbonate (DMDC), and unbound bis(fluorosulfonyl)imide (FSI). - ) be.

[0021] In one aspect, the solvent may contain dimethyl carbonate (DMC), and a molar ratio of one or more salts to dimethyl carbonate (DMC) may be approximately 0.5.

[0022] In one aspect, the solvent may contain dimethyl dicarbonate (DMDC), and the molar ratio of one or more salts to dimethyl dicarbonate (DMDC) may be approximately 1.

[0023] In one aspect, the electrolyte system can have a dynamic viscosity of less than or equal to about 100 centipoise (cP) and the electrochemical cell can have an energy density of more than about 900 Wh / L.

[0024] In one aspect, the positive lithium-based electroactive material can contain elemental sulfur or a sulfur-containing active material.

[0025] In one aspect, the positive lithium-based electroactive material can be selected from the group consisting of nickel-manganese-cobalt 811 (NMC811), nickel-manganese-cobalt 622 (NMC622); lithium cobalt oxide (LiCoO2); lithium iron phosphate (LiFePO4); high-energy nickel-manganese-cobalt oxide (HENMC) (e.g., overlithed layered oxide cathode or lithium-rich NMC), lithium manganese-nickel oxide (LMNO); and combinations thereof.

[0026] Further areas of application will become apparent from the description provided herein. The description and specific examples in this summary serve solely for illustrative purposes and are in no way intended to limit the scope of this disclosure. DRAWINGS

[0027] The drawings described herein serve solely to illustrate selected embodiments and do not represent the entirety of possible realizations and are not intended to limit the scope of the present disclosure. Fig. Figure 1 is a schematic of an exemplary electrochemical battery cell with a lithium-containing negative electrode; Fig. 2 represents an electrolyte system comprising dimethyl carbonate (DMC) and having a molar ratio of one or more salts to dimethyl carbonate (DMC) of about 0.5; Fig. 3 represents an electrolyte system comprising dimethyl dicarbonate (DMDC) and having a molar ratio of one or more salts to dimethyl dicarbonate (DMDC) of about 1; Fig. Figure 4 is a graphical representation of the electron affinities and ionization potentials of comparative electrolyte systems; and Fig. Figure 5 is a graphical representation of the capacity conservation per cycle of the exemplary electrochemical cells and the efficiency per cycle.

[0028] The same reference symbols in the different views of the drawings refer to the same parts. DETAILED DESCRIPTION

[0029] Exemplary embodiments are provided to ensure that this disclosure is thorough and fully conveys its scope to those skilled in the art. Numerous specific details are presented, such as examples of specific compositions, components, devices, and methods, to facilitate a thorough understanding of embodiments of the present disclosure. Those skilled in the art will recognize that specific details may not be necessary, that exemplary embodiments can take many different forms, and that none of the embodiments is intended to limit the scope of the disclosure. In some exemplary embodiments, well-known methods, well-known device structures, and well-known techniques are not described in detail.

[0030] The terminology used herein serves solely to describe certain exemplary embodiments and is not intended to be restrictive in any way. As used herein, the singular forms "a" and "the" include the plural forms where appropriate, unless the context clearly excludes this. The terms "comprises," "comprehensive," "included," and "exhibit" are inclusive and therefore indicate the presence of the specified features, elements, combinations, steps, integers, processes, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, processes, elements, components, and / or groups thereof.Although the term “comprises” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, the term may, under certain considerations, be understood alternatively, for example, as a more limiting and restrictive term, such as “consisting of” or “consisting substantially of”. Thus, any embodiment that lists compositions, materials, components, elements, functions, integers, operations, and / or process steps expressly includes, in the present disclosure, embodiments consisting of, or consisting substantially of, such compositions, materials, components, elements, functions, numbers, operations, and / or process steps.In the case of "consisting of", the alternative embodiment excludes any additional compositions, materials, components, elements, functions, numbers, operations, and / or process steps, whereas in the case of "consisting essentially of", any additional compositions, materials, components, elements, functions, numbers, operations, and / or process steps that materially impair the basic and new properties are excluded from such an embodiment, however, any compositions, materials, components, elements, functions, integers, operations, and / or process steps that materially do not impair the basic and new properties may be included in the embodiment.

[0031] All procedures, processes, and operations described herein are not to be interpreted as meaning that the described or depicted sequence is absolutely necessary, unless specifically stated as the order of execution. It should also be noted that additional or alternative steps may be applied unless otherwise specified.

[0032] When a component, element, or layer is described as "on / at," "interacting with," "connected with," or "coupled with" another component, element, or layer, it may be directly on / at, interacting with, connected to, or coupled with that other component, element, or layer, or there may be intervening elements or layers. Conversely, when an element is described as "directly on / at," "directly interacting with," "directly connected with," or "directly coupled with" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements are to be understood in the same way (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.).As used here, the term “and / or” includes all combinations of one or more of the related listed elements.

[0033] Although the terms first, second, third, etc., may be used here to describe different steps, elements, components, areas, layers, and / or sections, these steps, elements, components, areas, layers, and / or sections are not intended to be restricted by these expressions. These terms are used only to distinguish one step, element, component, area, layer, or section from another. Terms such as "first," "second," and other numerical terms, when used here, do not imply any sequence or order unless clearly indicated by the context.Thus, a first step, first element, component, area, layer or section discussed below could be referred to as a second step, second element, second component, second area, second layer or second section without deviating from the teaching of the exemplary embodiments.

[0034] Spatial or temporal terms, such as "before," "after," "inner," "outer," "below," "under," "lower," "above," "upper," and the like, can be used here to better describe the relationship of one element or property to other element(s) or property(ies), as illustrated in the figures. Spatial or temporal terms may also be intended to describe various arrangements of the device or system in use or operation, in addition to the orientation shown in the figures.

[0035] Throughout this disclosure, numerical values ​​generally represent approximate measurements or limits of ranges, including minor deviations from the specified values ​​and embodiments that exhibit approximately the stated value, as well as those with exactly the stated value. In contrast to the application examples provided at the end of the detailed description, all numerical values ​​of the parameters (e.g., quantities or conditions) in this specification, including the appended claims, are to be understood in all cases as being "approximately," regardless of whether or not "approximately" actually precedes the numerical value. "Approximately" indicates that the disclosed numerical value permits a certain degree of inaccuracy (with a certain approximation to exactness in the value; approximately or realistically close to the value; close to).If the imprecision provided by "approximately" is not otherwise understood in technical circles by this ordinary meaning, then "approximately," as used herein, indicates at least variations resulting from ordinary methods of measurement and the use of such parameters. For example, "about" may include a variation of less than or equal to 5%, possibly less than or equal to 4%, possibly less than or equal to 3%, possibly less than or equal to 2%, possibly less than or equal to 1%, possibly less than or equal to 0.5%, and, under certain considerations, possibly less than or equal to 0.1%.

[0036] Furthermore, the disclosure of ranges includes the disclosure of all values ​​and further subdivided ranges within the entire range, including the endpoints and subranges specified for the ranges.

[0037] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings.

[0038] The present technology relates to improved electrochemical cells, in particular lithium-ion or, more specifically, lithium-metal batteries, which can be used in vehicle applications. However, the current technology can also be used in other electrochemical devices, especially those containing lithium, such as lithium-sulfur batteries. Therefore, the treatment of a lithium-ion battery in this context is not limiting.

[0039] An exemplary and schematic representation of a battery 20 that performs lithium-ion cycles is shown in Fig. Figure 1 shows the battery 20 comprising a negative electrode 22, a positive electrode 24, and a porous separator 26 (e.g., a microporous or nanoporous polymeric separator) positioned between the two electrodes 22 and 24. The separator 26 contains an electrolyte 30, which may also be present in the negative electrode 22 and the positive electrode 24. A negative electrode current collector 32 may be located on or near the negative electrode 22, and a positive electrode current collector 34 may be positioned on or near the positive electrode 24. The negative electrode current collector 32 and the positive electrode current collector 34 each collect electrons and transport the free electrons to and from an external circuit 40. An interruptible external circuit 40 and consumer 42 connects the negative electrode 22 (via its current collector 32) and the positive electrode 24 (via its current collector 34).

[0040] The porous separator 26, which serves both as an electrical insulator and for mechanical support, is inserted between the negative electrode 22 and the positive electrode 24 to prevent physical contact and thus avoid the occurrence of a short circuit. In addition to providing a physical barrier between the two electrodes 22 and 24, the porous separator 26 can provide a minimal resistance path for the internal passage of lithium ions (and their associated anions) during the lithium-ion cycle, thereby facilitating the function of the battery 20. While in lithium-ion batteries lithium is incorporated into the active materials of the electrode, in a lithium-sulfur battery the lithium detaches from the negative electrode and migrates to the positive electrode, reacting / plating during discharge, while remaining on the negative electrode during charging.

[0041] The battery 20 can be recharged and made usable at any time by connecting an external power source to it, thus reversing the electroactive reactions of battery discharge. Connecting an external power source to the battery 20 forces the generation of electrons and the release of lithium ions from the positive electrode 25. The electrons, which flow back to the negative electrode 22 through the external circuit 40, and the lithium ions, which are transported back to the negative electrode 22 through the electrolyte 30 and the separator 26, recombine at the negative electrode 22 and replenish it with stored lithium for use in the next battery discharge cycle. Thus, each discharge and charge event is considered a cycle in which lithium ions are switched between the positive electrode 24 and the negative electrode 22.

[0042] The external power source that can be used to charge the battery 20 can vary in size, construction, and specific end application. Some notable and exemplary external sources include, but are not limited to, an AC wall outlet and a motor vehicle alternator. In many lithium-ion battery configurations, the negative current collector 32, the negative electrode 22, the separator 26, the positive electrode 24, and the positive current collector 34 are each fabricated as relatively thin layers (for example, from a few micrometers to one millimeter or less in thickness) and assembled in layers that are connected in electrical parallel to provide a suitable energy package.

[0043] Furthermore, the battery 20 may include a variety of other components which, although not shown here, are well known to experts. For example, the battery 20 may include a casing, seals, terminal caps, tabs, battery terminals, and any other conventional components or materials that may be located within the battery 20, including, as a non-limiting example, between or around the negative electrode 22, the positive electrode 24, and / or the separator 26. As mentioned above, the size and shape of the battery 20 may vary depending on the specific application for which it is designed. Battery-powered vehicles and portable consumer electronics are two examples where the battery 20 would likely have a different size, capacity, and power output.The battery 20 can also be connected in series or parallel with other, similar lithium-ion cells or batteries to produce a greater voltage output, energy and power when required by the consumer 42.

[0044] Accordingly, the battery 20 can generate electrical current at a load 42, which may be operationally connected to the external circuit 40. While the load 42 can be any number of electrically driven devices, some specific examples of current-consuming load devices include an electric motor for a hybrid or fully electric vehicle, a laptop computer, a tablet computer, a mobile phone, and a cordless power tool or household appliances as non-limiting examples. The load device 42 can also be an energy-generating device that charges the battery 20 to store the energy. In some other variations, the electrochemical cell can be a supercapacitor, such as a lithium-ion-based supercapacitor.

[0045] With renewed reference to Fig. 1. In certain cases, the porous separator 26 may include a microporous polymeric separator, including a polyolefin as a non-restrictive example. The polyolefin may be a homopolymer (derived from a single monomer component) or a heteropolymer (derived from more than one monomer component), which may be either linear or branched. If a heteropolymer is derived from two monomer components, the polyolefin may adopt any copolymer chain arrangement, including that of a block copolymer or a statistical copolymer. Likewise, a polyolefin that is a heteropolymer derived from more than two monomer components may also be a block copolymer or a statistical copolymer. In certain aspects, the polyolefin may be polyethylene (PE), polypropylene (PP), or a mixture of PE and PP, or a multilayered structured porous film of PE and / or PP.Commercially available microporous polymer membranes 26 made of polyolefin close CELGARD. ® 2500 (a single-layer polypropylene separator) and CELGARD ® 2320 (a three-layer polypropylene / polyethylene / polypropylene separator) from Celgard LLC.

[0046] If the porous separator 26 is a microporous polymeric separator, it can be a single layer or a multilayer laminate produced via either a dry or wet process. For example, in one embodiment, a single layer of the polyolefin can constitute the entire microporous polymeric separator 26. In other aspects, the separator 26 can be a fibrous membrane with numerous pores extending between opposing surfaces and can, for example, have a thickness of less than one millimeter. As another example, the microporous polymeric separator 26 can also be composed of several separate layers of the same or dissimilar polyolefin. Furthermore, the porous separator 26 can be blended with a ceramic material or its surface can be coated with a ceramic material.A ceramic coating can, for example, contain aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), or combinations thereof. Various conventional polymers and commercial products for the formation of separator 26 are considered, as well as the many manufacturing processes that can be used to produce such a microporous polymeric separator 26.

[0047] In various aspects, the positive electrode 24 can be formed from a lithium-based active material in which sufficient intercalation and disintercalation, alloying and delegation, or coating and stripping of lithium is possible when it serves as the positive terminal of the battery 20. The electroactive materials of the positive electrode 24 can include one or more transition metals, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. Two exemplary classes of known electroactive materials that can be used to form the positive electrode 24 are layered lithium transition metal oxides and spinel-phase lithium transition metal oxides.

[0048] For example, in certain cases the positive electrode 24 can contain a spinel-type transition metal oxide, such as lithium manganese oxide (Li (1+x) Mn(2-x) O4), where x is typically less than 0.15, including LiMn2O4 (LMO) and lithium manganese nickel oxide LiMn 1.5 Ni 0,5 O4(LMNO). In certain cases, the positive electrode can consist of 24 layer materials such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), a lithium nickel manganese cobalt oxide (Li(Ni) x Mn y Co z )O2) include, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, and x + y + z = 1, including LiMn 0,33 Ni 0,33 Co 0,33 O2, a lithium-nickel-cobalt metal oxide ( (1-x-y) Co x M y O2), where 0 <x<1, 0<y<1 und M Al, Mn oder dergleichen sein können. Andere bekannte Lithium-Übergangsmetallverbindungen wie Lithiumeisenphosphat (LiFePO4) oder Lithiumeisenfluorphosphat (Li2FePO4F) können ebenfalls verwendet werden. In bestimmten Aspekten kann die positive Elektrode 24 ein elektroaktives Material beinhalten, das Mangan, wie beispielsweise Lithiummanganoxid (Li (1+x) Mn(2-x) O4), a mixed lithium manganese nickel oxide (LiMn (2-x) Ni x O4), where 0 ≤ x ≤ 1, and / or a lithium manganese nickel cobalt oxide (e.g., LiMn 1 / 3 Ni 1 / 3 Co 1 / 3 O2). In a lithium-sulfur battery, positive electrodes can contain elemental sulfur or a sulfur-containing active material.

[0049] In certain variations, the electroactive material used to form the positive electrode 24 can have a maximum potential greater than or equal to approximately 4 V, optionally greater than or equal to approximately 5 V, and in certain aspects also greater than or equal to approximately 8 V. For example, under certain circumstances, the positive electrode 24 can comprise a positive lithium-based electroactive material selected from the group consisting of nickel-manganese-cobalt 811 (NMC811); nickel-manganese-cobalt 622 (NMC622); lithium cobalt oxide (LiCoO2); lithium iron phosphate (LiFePO4); high-energy nickel-manganese-cobalt oxide (HENMC) (e.g., overlithed layered oxide cathode or lithium-rich NMC); lithium manganese-nickel oxide (LMNO); and combinations thereof.

[0050] In certain variations, these positive active materials can be combined with an optional electrically conductive material and at least one polymeric binder to structurally reinforce the lithium-based active material along with optionally dispersed electrically conductive particles. For example, the active materials and optional conductive materials can be cast with binders such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM), carboxymethoxylcellulose (CMC), nitrile butadiene rubber (NBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, or lithium alginate. Electrically conductive materials can include graphite, carbon-containing materials, nickel powder, metal particles, or a conductive polymer.Carbon-containing materials can include, by a non-limiting example, KETCHEN™ carbon black, DENKA™ carbon black, acetylene carbon black, and the like. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, and the like. In certain aspects, mixtures of conductive materials may be used. The positive current collector 34 can be made of aluminum (Al) or any other suitable electrically conductive material known to those skilled in the art.

[0051] In various aspects, the negative electrode 22 incorporates an electroactive material that can serve as the negative terminal of the battery 20. The negative electrode 22 can thus include the electroactive material and, optionally, another electrically conductive material, as well as one or more polymeric bonding materials for structurally holding the lithium host material together. The electroactive material comprises lithium in various aspects and can be lithium metal. In certain variations, the negative electrode 22 is a film or layer formed from lithium metal or a lithium alloy. As mentioned above, metallic lithium for use in the negative electrode (e.g., 22) of a rechargeable battery (e.g., 20) offers several potential advantages, including the highest theoretical capacity (e.g., approximately 3860 mAh / g (LiC6: 339 mAh / g; Li 3.75Si: 1860 mAh / g)) and lowest electrochemical potential. Furthermore, batteries (e.g., 20) with lithium-metal anodes (e.g., 22) can have a higher energy density (e.g., greater than about 800 Wh / L and greater than about 350 Wh / kg), which can potentially double the storage capacity.

[0052] In certain variations, the negative electrode 22 can optionally include a further electrically conductive material as well as one or more polymeric binders for structurally holding the lithium host material together. As a non-limiting example, in one embodiment the negative electrode 22 can include an active material containing lithium metal particles (e.g., lithium foil) mixed with a binder material selected from the group consisting of: polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) or carboxymethoxylcellulose (CMC), a nitrile butadiene rubber (NBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof. Suitable additional electrically conductive materials can include carbon-containing materials or a conductive polymer.Carbon-containing materials can include, by a non-limiting example, KETCHEN™ carbon black, DENKA™ carbon black, acetylene carbon black, and the like. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, and the like. In certain aspects, mixtures of conductive materials may be used. The negative electrode current collector 32 can be made of copper (Cu) or any other suitable electrically conductive material known to those skilled in the art.

[0053] As mentioned previously, each of the separators 26, the negative electrodes 22, and the positive electrodes 24 can contain an electrolyte system 30 capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24. The electrolyte system 30 can be a non-aqueous liquid electrolyte solution with a bound component. The bound component can comprise one or more salts associated with or bound to an organic solvent or a mixture of organic solvents. In certain cases, the one or more lithium salts can be selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof, and the solvent can comprise a carbonate-based solvent.For example, the bound portion of the electrolyte system 30 may comprise one or more lithium salts selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof, and a solvent comprising one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and combinations thereof. The one or more salts may have a concentration in the electrolyte system of greater than or equal to approximately 4M, optionally greater than or equal to approximately 4.5M, and in certain aspects optionally greater than or equal to approximately 5M. In one variation, the solvent may comprise dimethyl carbonate (DMC), and a molar ratio of one or more salts to dimethyl carbonate (DMC) may be approximately 0.5.In another variation, the solvent can include dimethyl dicarbonate (DMDC), and the molar ratio of one or more salts to dimethyl dicarbonate (DMDC) can be approximately 1.

[0054] In various aspects, the electrolyte system 30 exhibits an ionization potential that is greater than its electron affinity. For example, the electrolyte system 30 may have a calculated electron affinity less than or equal to approximately 2 eV and a calculated ionization potential greater than or equal to approximately 10 eV. In certain cases, the electrolyte system 30 may have a viscosity of less than or equal to approximately 100 centipoise (cP), and a battery 20 including the electrolyte system 30 may have an energy density of more than approximately 900 Wh / L.

[0055] In various aspects, the bound fraction of the electrolyte system 30 improves or supports the efficiency of the battery 20 by suppressing or minimizing side reactions that can occur when the solvent and / or salts are unbound or free species in the electrolyte system 30 that can react with the lithium (Li) metal of the negative electrode 22. Side reactions can impair the coulombic efficiency and lifetime of rechargeable batteries through the consumption of the lithium (Li) metal and the electrolyte. Carbonate-based electrolyte systems generally exhibit good compatibility with high-energy cathodes (e.g., cathodes with a maximum potential greater than or equal to approximately 5 V and, in certain aspects, also greater than or equal to approximately 8.0 V).However, carbonate-based electrolyte systems with low concentrations (less than approximately 4M and in certain aspects less than approximately 3M) can exhibit low lithium cycle efficiency (e.g., less than or equal to approximately 23.6%). By providing electrolyte systems 30 with higher salt concentrations (e.g., greater than or equal to approximately 4M, optionally greater than or equal to approximately 4.5M, and in certain aspects also greater than or equal to approximately 5M), the efficiency of the battery 20 can be improved.

[0056] The electrolyte system 30 can be substantially free of such free or unbound compounds (e.g., solvents and / or salts). Electrolyte system 30 can comprise less than or equal to approximately 0.5 wt%, optionally less than or equal to approximately 0.25 wt%, optionally less than or equal to approximately 0.1 wt%, and in certain aspects 0 wt% of the free or unbound undesirable species, such as unbound salts or unbound solvents (e.g., dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC)).

[0057] The embodiments of the present technology are further illustrated by the following non-examples. Example 1

[0058] Fig. Figure 2 illustrates an electrolyte system 55 that has been prepared according to certain aspects of the present disclosure. In particular, it presents Fig. 2 an electrolyte system 55 comprising one or more salts bound to a solvent to form a bound fraction. Fig. Figure 2 represents an electrolyte system 55 comprising one or more salts bound to a solvent to form a bound fraction. The electrolyte system 55 includes a bound fraction comprising lithium bis(fluorosulfonyl)imide (LiFSI) and dimethyl carbonate (DMC). The electrolyte system 55 contains a concentration of lithium bis(fluorosulfonyl)imide (LiFSI) of approximately 5 M and a molar ratio of lithium bis(fluorosulfonyl)imide (LiFSI) to dimethyl carbonate (DMC) of approximately 0.5.

[0059] As illustrated, all dimethyl carbonate (DMC) molecules bind to lithium (Li). + Thus, dimethyl carbonate (DMC) and bis(fluorosulfonyl)imide (FSI) can be used. -) are immobilized and the electrolyte system 55 can be essentially free of free or unbound dimethyl carbonate (DMC) and free or unbound bis(fluorosulfonyl)imide (FSI) - The electrolyte system 55 may contain less than or equal to approximately 0.5 wt%, optionally less than or equal to approximately 0.25 wt%, optionally less than or equal to approximately 0.1 wt%, and in certain aspects 0 wt% of the free or unbound undesired species free or unbound dimethyl carbonate (DMC) and free or unbound bis(fluorosulfonyl)imide (FSI). - ) include. This eliminates or minimizes harmful side reactions and improves the efficiency of the batteries, including the electrolyte system 55. Example 2

[0060] Fig. Figure 3 illustrates an electrolyte system 60 that has been prepared according to certain aspects of the present disclosure. In particular, it presents Fig. 2 represents an electrolyte system 60 comprising one or more salts bound to a solvent to form a bound fraction. Fig. Figure 2 represents an electrolyte system 60 comprising one or more salts bound to a solvent to form a bound fraction. The electrolyte system 60 includes a bound fraction comprising lithium bis(fluorosulfonyl)imide (LiFSI) and dimethyl dicarbonate (DMDC). The electrolyte system 60 contains a concentration of lithium bis(fluorosulfonyl)imide (LiFSI) of approximately 5 M and a molar ratio of lithium bis(fluorosulfonyl)imide (LiFSI) to dimethyl dicarbonate (DMDC) of approximately 1.

[0061] As illustrated, all dimethyl dicarbonate (DMDC) molecules bind to lithium (Li + Thus, dimethyl dicarbonate (DMDC) and bis(fluorosulfonyl)imide (FSI) can be used. -) are immobilized and the electrolyte system 60 can be essentially free of free or unbound dimethyl dicarbonate (DMDC) and free or unbound bis(fluorosulfonyl)imide (FSI) - The electrolyte system 60 may contain less than or equal to approximately 0.5 wt%, optionally less than or equal to approximately 0.25 wt%, optionally less than or equal to approximately 0.1 wt%, and in certain aspects 0 wt% of the free or unbound undesired species free or unbound dimethyl dicarbonate (DMDC) and free or unbound bis(fluorosulfonyl)imide (FSI). - ) include. This eliminates or minimizes harmful side reactions and improves the efficiency of the batteries, including the electrolyte system 60. Example 3

[0062] Fig. Figure 4 illustrates comparative electrolyte systems 70 and 80. Electrolyte system 70 is prepared according to certain aspects of the present disclosure and comprises one or more salts selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof, and a solvent comprising one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and combinations thereof. The one or more salts have a concentration in electrolyte system 70 of greater than or equal to about 4 M and a molar ratio greater than or equal to about 0.5 to less than or equal to about 1. Thus, electrolyte system 70 is essentially free of unbound dimethyl carbonate (DMC), unbound dimethyl dicarbonate (DMDC), and unbound bis(fluorosulfonyl)imide (FSI). - ).

[0063] The electrolyte system 80 also comprises one or more salts selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI), and combinations thereof, as well as a solvent comprising one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC), and combinations thereof. However, the one or more salts have a concentration in electrolyte system 80 of less than approximately 4 M.

[0064] As illustrated, the presence of the bound fraction in the electrolyte system 70 decreases the electron affinity (eV) without decreasing the ionization potential (eV). The y-axis or vertical axis 90 of Fig. Figure 4 represents the electron affinity (eV), while the x-axis or horizontal axis 95 represents the ionization potential (eV). The electrolyte system 70, including the bound fraction, can have a calculated electron affinity less than or equal to approximately 2 eV and a calculated ionization potential greater than or equal to approximately 10 eV. Whereas the electrolyte system 80, including the bound fraction, can have a calculated electron affinity of greater than or equal to approximately 2.5 eV to less than or equal to approximately 3 eV and a calculated ionization potential of greater than or equal to approximately 10 eV. Example 4

[0065] Fig.Figure 5 presents the charge-discharge and efficiency profiles (e.g., cycle life) of comparatively high-performance 20 µm Li-NMC 622 electrochemical cells 100 and 200, including negative electrodes made of metallic lithium and different electrolyte systems. The first or left y-axis 105 shows the capacity maintenance in milliampere-hours (mAh), while the second or right y-axis 115 represents the efficiency and the x-axis 110 the number of cycles. The electrochemical cell 100 includes an electrolyte system that has been prepared according to certain aspects of this disclosure. In particular, the electrolyte system of the electrochemical cell 100 includes a bound component of lithium bis(fluorosulfonyl)imide (LiFSI) and dimethyl carbonate (DMC). The electrolyte system of the electrochemical cell 100 has a salt concentration of about 5 M and a molar ratio of lithium bis(fluorosulfonyl)imide (LiFSI) to dimethyl carbonate (DMC) of about 0.5.The electrochemical cell 200 incorporates an electrolyte system comprising lithium bis(fluorosulfonyl)imide (LiFSI) and dimethoxyethane (DME). The electrolyte system of the electrochemical cell 100 has a salt concentration of approximately 4 M. As illustrated, the electrochemical cell 100 has a full-cycle efficiency of approximately 99.9% or greater, while the electrochemical cell 200 has a full-cycle efficiency of approximately 99.7%.

[0066] The foregoing description of the embodiments serves only for illustration and description. It is not exhaustive and is not intended to limit the disclosure in any way. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but may be interchangeable and usable in a selected embodiment, even if this is not specifically shown or described. Various variations are also conceivable. These variations do not constitute a deviation from the disclosure, and all modifications of this kind are understood to be part of the disclosure and fall within its scope of protection.

Claims

[1] Method for producing an electrolyte system that improves or increases the efficiency of an electrochemical cell, comprising a positive electrode comprising a positive lithium-based electroactive material and having a maximum potential greater than or equal to about 5 V, and a negative electrode comprising a negative electroactive material comprising lithium, the method comprising: Mixing one or more salts selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI) and combinations thereof, and a solvent comprising one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC) and combinations thereof, wherein a bound fraction with an ionization potential greater than an electron affinity is formed to create an electrolyte system that is substantially free of unbound dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC) and unbound bis(fluorosulfonyl)imide (FSI). - ) is, wherein one or more salts have a concentration in the electrolyte system of greater than or equal to approximately 4 M. [2] The method of claim 1, wherein the solvent comprises dimethyl carbonate (DMC) and the molar ratio of one or more salts to dimethyl carbonate (DMC) is about 0.

5. [3] The method of claim 1, wherein the solvent comprises dimethyl dicarbonate (DMDC) and the molar ratio of one or more salts to dimethyl dicarbonate (DMDC) is about 1. [4] Method according to claim 1, wherein the electrolyte system has a dynamic viscosity of less than or equal to about 100 centipoise (cP) and the electrochemical cell has an energy density of more than about 900 Wh / L. [5] Method according to claim 1, wherein the positive lithium-based electroactive material comprises elemental sulfur or a sulfur-containing active material. [6] The method of claim 1, wherein the positive lithium-based electroactive material is selected from the group consisting of nickel-manganese-cobalt 811 (NMC811), nickel-manganese-cobalt 622 (NMC622); lithium cobalt oxide (LiCoO2); lithium iron phosphate (LiFePO4); high-energy nickel-manganese-cobalt oxide (HENMC) (e.g., superlithed layered oxide cathode or lithium-rich NMC), lithium-manganese-nickel oxide (LMNO); and combinations thereof. [7] Method for improving or optimizing the anodic stability of an electrochemical cell that cycles lithium ions, the method comprising: Introducing an electrolyte system into the electrochemical cell, wherein the electrolyte system has a bound component with an ionization potential greater than an electron affinity and comprises one or more salts bound to a solvent, wherein the one or more salts have a concentration in the electrolyte system of greater than or equal to about 4 M and are selected from the group consisting of: lithium bis(fluorosulfonyl)imide (LiFSI), sodium bis(fluorosulfonyl)imide (NaFSI), potassium bis(fluorosulfonyl)imide (KFSI) and combinations thereof, and wherein the solvent comprises one or more solvents selected from the group consisting of: dimethyl carbonate (DMC), dimethyl dicarbonate (DMDC) and combinations thereof, wherein the electrolyte system is substantially free of unbound dimethyl carbonate (DMC), unbound dimethyl dicarbonate (DMDC) and unbound bis(fluorosulfonyl)imide (FSI). - ) is. [8] Method according to claim 7, wherein the electrochemical cell comprises a positive electrode with a positive lithium-based electroactive material having a maximum potential greater than or equal to about 5 V and a negative electrode with a negative electroactive material containing lithium, wherein the solvent comprises dimethyl carbonate (DMC) and the molar ratio of one or more salts to dimethyl carbonate (DMC) is about 0.

5. [9] Method according to claim 7, wherein the electrochemical cell comprises a positive electrode with a positive lithium-based electroactive material having a maximum potential greater than or equal to about 5 V and a negative electrode with a negative electroactive material containing lithium, wherein the solvent comprises dimethyl carbonate (DMC) and the molar ratio of one or more salts to dimethyl dicarbonate (DMDC) is about 1. [10] Method according to claim 7, wherein the electrolyte system has a viscosity of less than or equal to about 100 centipoise (cP) and the electrochemical cell has an energy density of more than about 900 Wh / L.

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