Ionic liquid electrolyte for battery pack circulating lithium ions and battery pack comprising same

Abstract

The invention provides an electrolyte of a battery pack for circulating lithium ions. The electrolyte comprises ethylene glycol dimethyl ether ionic liquid and cyclic ammonium ionic liquid. The ethylene glycol dimethyl ether ionic liquid comprises a cation component and an anion component which are basically equal in molar weight, the cation component comprises a complex of lithium (Li < + >) and ethylene glycol dimethyl ether, and the anion component comprises arsenate ions, phosphate ions, sulfimide ions, borate ions and / or chlorate ions. The cyclic ammonium ionic liquid comprises a cation component, wherein the cation component comprises piperidinium ions and / or pyrrolidinium ions; and an anionic component comprising arsenate ions, phosphate ions, sulfimide ions, borate ions, and / or chlorate ions. The electrolyte has a lithium concentration greater than or equal to 0.2 mol / L and less than or equal to 1.6 mol / L. The electrolyte can be used in batteries that cycle lithium ions and include silicon-containing electroactive negative electrode materials.

Description

Technical Field

[0001] This disclosure relates to electrolytes for cyclic lithium-ion battery packs, and more specifically to ionic liquid electrolytes for battery packs comprising a silicon-containing negative electrode and optionally a sulfide-based solid electrolyte. Background Technology

[0002] The information provided in this section is intended to generally introduce the background of this disclosure. The operations currently attributed to the inventors, to the extent described in this section, and aspects of the specification that may not have been otherwise identified as prior art at the time of application, are not expressly or impliedly acknowledged as prior art to this disclosure.

[0003] This disclosure relates to electrolytes for cyclic lithium-ion battery packs, and more specifically to ionic liquid electrolytes for battery packs comprising a silicon-containing negative electrode and optionally a sulfide-based solid electrolyte.

[0004] Lithium-ion battery packs are widely used in various electronic devices and, due to their high energy and power density, are promising candidates for meeting the requirements of electric vehicles, including hybrid electric vehicles. A typical secondary lithium-ion battery pack includes a negative electrode, a positive electrode, and an electrolyte that provides the medium for lithium-ion conduction between the negative and positive electrodes during battery discharge and charging. This electrolyte can be formulated to exhibit certain desired properties, including high ionic conductivity, good thermal stability, a wide electrochemical stability window, the ability to form a stable ion-conducting solid electrolyte interface on the surfaces of the positive and / or negative electrodes, and chemical compatibility with other components of the battery pack. Summary of the Invention

[0005] According to one or more embodiments of this disclosure, the electrolyte for a battery pack used in cycling lithium-ion batteries comprises an ethylene glycol dimethyl ether ionic liquid and a cyclic ammonium ionic liquid. The ethylene glycol dimethyl ether ionic liquid comprises substantially equimolar amounts of a cationic component and an anionic component, wherein the cationic component includes lithium (Li₂) + The electrolyte is a complex of ethylene glycol dimethyl ether, and the anionic component includes arsenate ions, phosphate ions, sulfonylimide ions, borate ions, chlorate ions, or combinations thereof. This cyclic ammonium ionic liquid comprises a cationic component and an anionic component, wherein the cationic component includes piperidinium ions, pyrrolidineonium ions, or combinations thereof, and the anionic component includes arsenate ions, phosphate ions, sulfonylimide ions, borate ions, chlorate ions, or combinations thereof. The electrolyte has a lithium concentration greater than or equal to 0.2 mol / L and less than or equal to 1.6 mol / L.

[0006] The electrolyte can have a viscosity of greater than or equal to 10 mPascal-second and less than or equal to 100 mPascal-second and an ionic conductivity of greater than or equal to 4 mSiemens / cm and less than or equal to 10 mSiemens / cm at 25°C.

[0007] At 25°C, ethylene glycol dimethyl ether ionic liquids can have a viscosity greater than 100 mPa·s, while cyclic ammonium ionic liquids can have a viscosity less than 100 mPa·s.

[0008] At 25°C, ethylene glycol dimethyl ether ionic liquids can have an ionic conductivity of less than or equal to 2 millisiemens / cm, while cyclic ammonium ionic liquids can have an ionic conductivity of greater than or equal to 4 millisiemens / cm.

[0009] The cationic component of ethylene glycol dimethyl ether ionic liquids may include lithium (Li). + Complexes of ethylene glycol dimethyl ether with monoethylene glycol dimethyl ether, ethyl ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, butyl diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or combinations thereof. The anionic component of the ethylene glycol dimethyl ether ionic liquid may include hexafluoroarsinate (AsF6). - ), hexafluorophosphate (PF6) - ), bis(fluorosulfonyl)imide (FSI), bis(trifluoromethyl)sulfonylimide (TFSI), tetrafluoroborate (LiBF4) - ), perchlorate (ClO4) - (or a combination thereof).

[0010] Ethylene glycol dimethyl ether ionic liquids can be formed from a mixture of ethylene glycol dimethyl ether and lithium salt. The molar ratio of ethylene glycol dimethyl ether to lithium salt in the mixture can be greater than or equal to 0.7:1 and less than or equal to 1.2:1.

[0011] The cationic component of the cyclic ammonium ionic liquid may include 1-methyl-1-ethylpyrrolidine. ([Py 12 ] + ), 1-propyl-1-methylpyrrolidine ([Py 13 ] + ), 1-Butyl-1-methylpyrrolidine ([Py 14 ] + ), 1-propyl-1-methylpiperidine ([PP 13 ] + ), 1-Butyl-1-methylpiperidine ([PP 14 ] +(or combinations thereof). The anionic component of cyclic ammonium ionic liquids may include hexafluoroarsinate (AsF6). - ), hexafluorophosphate (PF6) - ), bis(fluorosulfonyl)imide (FSI), bis(trifluoromethyl)sulfonylimide (TFSI), tetrafluoroborate (LiBF4) - ), perchlorate (ClO4) - ), or combinations thereof.

[0012] In various respects, the cationic component of the ethylene glycol dimethyl ether ionic liquid may include lithium (Li). + The complex of ethylene glycol dimethyl ether with tetraethylene glycol dimethyl ether, wherein the anionic component of the ethylene glycol dimethyl ether ionic liquid may include bis(fluorosulfonyl)imide (FSI), and the cationic component of the cyclic ammonium ionic liquid may include 1-propyl-1-methylpyrrolidine. ([Py 13 ] + Furthermore, the anionic component of the cyclic ammonium ionic liquid may include bis(fluorosulfonyl)imide (FSI).

[0013] The volume ratio of ethylene glycol dimethyl ether ionic liquid to cyclic ammonium ionic liquid in the electrolyte can be greater than or equal to 1:10 and less than or equal to 2:1.

[0014] Electrolytes can be essentially free of non-aqueous, non-protic organic solvents.

[0015] According to one or more embodiments of this disclosure, a cyclic lithium-ion battery pack includes a negative electrode, a positive electrode spaced apart from the negative electrode, a porous separator disposed between the negative and positive electrodes and having a plurality of open pores extending therethrough, and an electrolyte that wets the open pores of the porous separator and is configured to provide a medium for lithium ions to pass through the porous separator and conduct between the negative and positive electrodes. The negative electrode comprises an electroactive negative electrode material containing silicon. The positive electrode comprises an electroactive positive electrode material. The electrolyte comprises an ethylene glycol dimethyl ether ionic liquid and a cyclic ammonium ionic liquid. The ethylene glycol dimethyl ether ionic liquid comprises substantially equimolar amounts of a cationic component and an anionic component, wherein the cationic component includes lithium (Li₂) + A complex of ethylene glycol dimethyl ether, wherein the anionic component includes arsenate ions, phosphate ions, sulfonamide ions, borate ions, chlorate ions, or combinations thereof. This cyclic ammonium ionic liquid comprises a cationic component and an anionic component, wherein the cationic component includes piperidine. Ions, pyrrolidine The electrolyte contains ions or combinations thereof, and the anionic component includes arsenate ions, phosphate ions, sulfonamide ions, borate ions, chlorate ions, or combinations thereof. The electrolyte has a lithium concentration greater than or equal to 0.2 mol / L and less than or equal to 1.6 mol / L.

[0016] The electrolyte can have a viscosity of greater than or equal to 10 mPascal-second and less than or equal to 100 mPascal-second and an ionic conductivity of greater than or equal to 4 mSiemens / cm and less than or equal to 10 mSiemens / cm at 25°C.

[0017] The molar ratio of the cationic component to the anionic component in the ethylene glycol dimethyl ether ionic liquid can be greater than or equal to 0.7:1 and less than or equal to 1.2:1.

[0018] In various respects, the cationic component of the ethylene glycol dimethyl ether ionic liquid may include lithium (Li). + The complex of ethylene glycol dimethyl ether with tetraethylene glycol dimethyl ether, wherein the anionic component of the ethylene glycol dimethyl ether ionic liquid may include bis(fluorosulfonyl)imide (FSI), and the cationic component of the cyclic ammonium ionic liquid may include 1-propyl-1-methylpyrrolidine. ([Py 13 ] + Furthermore, the anionic component of the cyclic ammonium ionic liquid may include bis(fluorosulfonyl)imide (FSI).

[0019] The volume ratio of ethylene glycol dimethyl ether ionic liquid to cyclic ammonium ionic liquid in the electrolyte can be greater than or equal to 1:10 and less than or equal to 2:1.

[0020] The porous separator may include solid electrolyte particles. In this case, the solid electrolyte particles may include sulfide-based solid electrolyte materials. Sulfide-based solid electrolyte materials may include lithium sulfide (Li₂S) and at least one element selected from phosphorus (P), tin (Sn), silicon (Si), germanium (Ge), boron (B), gallium (Ga), and aluminum (Al).

[0021] The negative electrode may also contain polymer binders, conductive materials, and sulfide-based solid electrolyte particles.

[0022] Porous separators may include polymer membranes.

[0023] Electroactive positive electrode materials may contain sulfur.

[0024] Further applicability of this disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended to illustrate the invention and are not intended to limit the scope of this disclosure. Attached Figure Description

[0025] This disclosure will be more fully understood through detailed description and accompanying drawings, in which:

[0026] Figure 1This is a schematic perspective view of a motor vehicle powered by a battery pack comprising multiple battery modules.

[0027] Figure 2 yes Figure 1 A schematic cross-sectional view of a portion of a battery pack module, which includes multiple cycle lithium-ion electrochemical cells or battery packs.

[0028] Figure 3 This is a schematic cross-sectional view of a cyclic lithium-ion battery pack, which includes a negative electrode, a positive electrode, a porous separator defined by multiple solid electrolyte particles, and an electrolyte that wets the pores of the negative electrode, the positive electrode, and the porous separator. The electrolyte includes a mixture of ethylene glycol dimethyl ether ionic liquid and cyclic ammonium ionic liquid.

[0029] Figure 4 This is a schematic cross-sectional view of a cyclic lithium-ion battery pack, which includes a negative electrode, a positive electrode, a porous separator in the form of a polymer membrane, and an electrolyte that wets the pores of the negative electrode, the positive electrode, and the porous separator. The electrolyte includes a mixture of ethylene glycol dimethyl ether ionic liquid and cyclic ammonium ionic liquid.

[0030] In the accompanying drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. Detailed Implementation

[0031] The currently disclosed electrolyte comprises a mixture of ethylene glycol dimethyl ether ionic liquids and cyclic ammonium ionic liquids and is formulated for use in battery packs for cycling lithium-ions to establish a robust lithium-ion transport pathway. The disclosed electrolyte is chemically compatible with sulfide-based solid electrolytes and silicon-containing negative electrode materials, and therefore can contribute to improved cycle stability of battery packs containing such materials. The amount of cyclic ammonium ionic liquid in the disclosed electrolyte is sufficient to provide the electrolyte with a relatively low viscosity and relatively high ionic conductivity compared to ethylene glycol dimethyl ether ionic liquids, which allows the disclosed electrolyte to be used in battery packs requiring relatively high charge and discharge rate capabilities.

[0032] Figure 1 A motor vehicle 2 is depicted, driven by an electric motor 4, which draws power from a battery pack 6 comprising one or more battery modules 8. The battery modules 8 may be electrically coupled together in series and / or parallel arrangement to meet the capacity and power requirements of the electric motor 4. The vehicle 2 may be an all-electric vehicle and may be powered solely by the electric motor 4, or the vehicle 2 may be a hybrid electric vehicle and may be powered by both the electric motor 4 and an internal combustion engine (not shown).

[0033] like Figure 2As shown, each battery module 8 includes one or more electrochemical cells or battery packs 10 capable of cycling lithium-ions. In practice, the battery packs 10 in the battery module 8 are typically assembled as a stack of layers, including a negative electrode layer 12, a negative electrode current collector 13, a positive electrode layer 14, a positive electrode current collector 15, and a separator layer 16. Each battery pack 10 is defined by the negative electrode layer 12 and the positive electrode layer 14, which are spaced apart from each other by the separator layer 16. In practice, the separator layer 16 may be impregnated with an electrolyte, which provides a medium for lithium-ion conduction between the negative electrode layer 12 and the positive electrode layer 14, or the separator layer 16 itself may act as the electrolyte. The negative electrode layer 12 is disposed on and electrically communicated with the negative electrode current collector 13, and the positive electrode layer 14 is disposed on and electrically communicated with the positive electrode current collector 15. Figure 2 As shown, for efficiency, the layers can be stacked such that some negative electrode current collectors 13 and some positive electrode current collectors 15 are double-sided and include a negative electrode layer 12 or a positive electrode layer 14 on each side. In this arrangement, adjacent negative electrode layers 12 and positive electrode layers 14 share a single negative electrode current collector 13 or a single positive electrode current collector 15.

[0034] Figure 3 An electrochemical battery or battery pack 20 for cycling lithium-ion batteries is depicted. The battery pack 20 generates current during discharge, which can be used to power a load device (e.g., an electric motor 4), and can be charged by connecting to a power source. Similar to... Figure 1 and Figure 2 The battery pack 10 shown, in various respects, can be used to power the electric motor 4 of the motor vehicle 2. Additionally or alternatively, the battery pack 20 can be used in other transportation applications (e.g., motorcycles, boats, tractors, buses, motorcycles, mobile homes, campervans, tanks, and aircraft), and can be used to power stationary and / or portable electronic devices, components, and devices used in a variety of other industries and applications, including industrial, residential and commercial buildings, consumer products, industrial equipment and machinery, agricultural or farm equipment, and heavy machinery, as examples only.

[0035] Battery pack 20 includes a negative electrode 22, a positive electrode 24, a porous separator 26, and an electrolyte 28 impregnated within open pores defined in the negative electrode 22, the positive electrode 24, and the porous separator 26. The negative electrode 22 is disposed on the main surface of the negative electrode current collector 30 and has a main surface 38 facing the positive electrode 24. The positive electrode 24 is disposed on the main surface of the positive electrode current collector 32 and has a main surface 40 facing the negative electrode 22. In practice, the negative electrode current collector 30 and the positive electrode current collector 32 are electrically coupled to a power source or load 34 (e.g., a motor 4) via an external circuit 36. The negative electrode 22 and the positive electrode 24 are configured to establish an electrochemical potential difference between them when the battery pack 20 is at least partially charged. During the discharge of the battery pack 20, the electrochemical potential established between the negative electrode 22 and the positive electrode 24 drives spontaneous reduction and oxidation (redox) reactions within the battery pack 20 and the release of lithium ions and electrons from the negative electrode 22. Released lithium ions move from the negative electrode 22 to the positive electrode 24 through the electrolyte 28 and porous separator 26, while electrons move from the negative electrode 22 to the positive electrode 24 through external circuitry 36, thereby generating an electric current. After the negative electrode 22 has been partially or completely depleted of lithium, the battery pack 20 can be charged by connecting the negative electrode 22 and the positive electrode 24 to a power source 34, thereby driving a non-spontaneous redox reaction within the battery pack 20 and releasing lithium ions and electrons from the positive electrode 24. Repeated discharge and charge cycles of the battery pack 20 are referred to herein as "cycles," where a complete charge followed by a complete discharge is considered a complete cycle.

[0036] Electrolyte 28 is ionicly conductive and is configured to provide a medium for the conduction of lithium ions through the negative electrode 22, the positive electrode 24, and the porous separator 26, and between the negative electrode 22, the positive electrode 24, and the porous separator 26. Electrolyte 28 is configured to have high ionic conductivity, high thermal stability, low volatility, and excellent resistance to electrochemical oxidation and reduction, providing the battery pack 20 with relatively high charge and discharge rate capabilities and improved cycle stability. Electrolyte 28 wets the main surface 38 of the negative electrode 22 and the main surface 40 of the positive electrode 24, and wets the open pores defined in the negative electrode 22, the positive electrode 24, and the porous separator 26. Electrolyte 28 is configured to facilitate the conduction of lithium ions through the battery pack 20 and maximize the capacity of the battery pack 20, for example, by establishing robust lithium-ion transport channels through the negative electrode 22, the positive electrode 24, and the porous separator 26, and by establishing robust interfacial contacts with the electroactive materials of the negative electrode 22 and the positive electrode 24.

[0037] Electrolyte 28 comprises a mixture of ethylene glycol dimethyl ether ionic liquid and cyclic ammonium ionic liquid. The ethylene glycol dimethyl ether ionic liquid is formulated to provide electrolyte 28 with high thermal stability, low volatility, excellent resistance to electrochemical oxidation and reduction, and good chemical compatibility with sulfide-based solid electrolyte materials. The cyclic ammonium ionic liquid is formulated to dilute the ethylene glycol dimethyl ether ionic liquid, thereby providing electrolyte 28 with an ideally low viscosity. Furthermore, the cyclic ammonium ionic liquid is formulated to provide electrolyte 28 with high ionic conductivity and good chemical compatibility with silicon-containing electroactive negative electrode materials, which can contribute to improving the cycle stability of battery pack 20. Compared to cyclic ammonium ionic liquid, ethylene glycol dimethyl ether ionic liquid can have relatively higher viscosity and relatively lower ionic conductivity. The amount of cyclic ammonium ionic liquid contained in electrolyte 28 is sufficient to provide electrolyte 28 with appropriately low viscosity and sufficiently high ionic conductivity. In all respects, the volume ratio of ethylene glycol dimethyl ether ionic liquid to cyclic ammonium ionic liquid (ethylene glycol dimethyl ether ionic liquid: cyclic ammonium ionic liquid) in electrolyte 28 can be greater than or equal to 1:10, optionally greater than or equal to 1:8, optionally greater than or equal to 1:6, or optionally greater than or equal to 1:4 and less than or equal to 2:1, optionally less than or equal to 1:1, or optionally less than or equal to 1:2.

[0038] In all respects, electrolyte 28 may have a viscosity at approximately 25°C that is greater than or equal to 10 mPa·s, optionally greater than or equal to 20 mPa·s, or optionally greater than or equal to 40 mPa·s and less than or equal to 110 mPa·s, optionally less than or equal to 100 mPa·s, optionally less than or equal to 80 mPa·s, or optionally less than or equal to 60 mPa·s. Electrolyte 28 may have an ionic conductivity at approximately 25°C that is greater than or equal to 1 millisiemens / cm (mS / cm), optionally greater than or equal to 2 mS / cm, optionally greater than or equal to 3 mS / cm, optionally greater than or equal to 4 mS / cm, or optionally greater than or equal to 4.5 mS / cm and less than or equal to 10 mS / cm. The lithium ions (Li...) in electrolyte 28... + The concentration can be greater than or equal to 0.2 mol / L (mol / L or Molar), optionally greater than or equal to 0.5 Molar, or optionally greater than or equal to 0.8 Molar and less than or equal to 1.6 Molar, optionally less than or equal to 1.5 Molar, or optionally less than or equal to 1.2 Molar. In all respects, the Li in electrolyte 28 + The concentration can be approximately 1 Molar.

[0039] Ethylene glycol dimethyl ether ionic liquids comprise cationic and anionic components. In various embodiments, the cationic and anionic components may be present in substantially equimolar amounts in the ethylene glycol dimethyl ether ionic liquid, and the ethylene glycol dimethyl ether ionic liquid may be referred to as a solvated ionic liquid. The ethylene glycol dimethyl ether ionic liquid may have a viscosity at about 25°C greater than or equal to 100 mPa·s, optionally greater than or equal to 110 mPa·s, optionally greater than or equal to 150 mPa·s, or optionally greater than or equal to 180 mPa·s, and an ionic conductivity greater than or equal to 1 mS / cm and less than or equal to 2 mS / cm.

[0040] The cationic components of ethylene glycol dimethyl ether ionic liquids include lithium (Li). + This is a complex of ethylene glycol dimethyl ether (R(OCH2CH2)) and ethylene glycol dimethyl ether. Ethylene glycol dimethyl ether is an ethylene glycol diether with the molecular formula R(OCH2CH2). n OR, where n is 1, 2, 3, or 4, and R is methyl (-CH3 or Me), ethyl (-CH2CH3 or Et), or butyl (-CH2CH2CH2CH3 or Et). Specific examples of ethylene glycol dimethyl ethers include monoethylene glycol dimethyl ether (n = 1 and R = Me), ethyl ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, butyl diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. In all respects, the cationic components of ethylene glycol dimethyl ether ionic liquids include lithium (Li). + A complex of ) and tetraethylene glycol dimethyl ether.

[0041] The anionic components of the ethylene glycol dimethyl ether ionic liquids include arsenate ions, phosphate ions, sulfonamide ions, borate ions, chlorate ions, or combinations thereof. An example of an arsenate ion is hexafluoroarsenate (AsF6-). An example of a phosphate ion is hexafluorophosphate (PF6-). Examples of sulfonamide ions include bis(fluorosulfonyl)imide (N(FSO2)2-) (FSI), bis(trifluoromethyl)sulfonylimide (N(CF3SO2)2-) (TFSI), and combinations thereof. An example of a borate ion is tetrafluoroborate (BF4-). An example of a chlorate ion is perchlorate (ClO4-). In all respects, the anionic components of the ethylene glycol dimethyl ether ionic liquids include bis(fluorosulfonyl)imide (FSI).

[0042] Ethylene glycol dimethyl ether ionic liquids can be formed from mixtures of ethylene glycol dimethyl ether and lithium salts. In such cases, the ethylene glycol dimethyl ether can include monoethylene glycol dimethyl ether, ethyl ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, butyl diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or combinations thereof, and the lithium salt can include lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethane)sulfonylimide (LiN(CF3SO2)2) (LiTFSI), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiFSI), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), or combinations thereof. In all respects, ethylene glycol dimethyl ether ionic liquids can be formed from mixtures of tetraethylene glycol dimethyl ether and LiFSI. In various embodiments, ethylene glycol dimethyl ether and lithium salt can be mixed in substantially equimolar amounts to form an ethylene glycol dimethyl ether-based ionic liquid. For example, the molar ratio of ethylene glycol dimethyl ether to lithium salt (ethylene glycol dimethyl ether: lithium salt) in the ethylene glycol dimethyl ether-based ionic liquid can be greater than or equal to 0.7:1, optionally greater than or equal to 0.8:1, or optionally greater than or equal to 0.9:1 and less than or equal to 1.2:1, or optionally less than or equal to 1.1:1. In all respects, the molar ratio of ethylene glycol dimethyl ether to lithium salt (ethylene glycol dimethyl ether: lithium salt) in the ethylene glycol dimethyl ether-based ionic liquid can be approximately 1:1.

[0043] This cyclic ammonium ionic liquid comprises both cationic and anionic components. The cyclic ammonium ionic liquid may have a viscosity at about 25°C greater than or equal to 10 mPa·s, optionally greater than or equal to 20 mPa·s, or optionally greater than or equal to 30 mPa·s and less than or equal to 100 mPa·s, optionally less than or equal to 60 mPa·s, or optionally less than or equal to 50 mPa·s. In all respects, the cyclic ammonium ionic liquid may have a viscosity of about 40 mPa·s at about 25°C. The cyclic ammonium ionic liquid may have an ionic conductivity at about 25°C greater than or equal to 4 mS / cm, optionally greater than or equal to 6 mS / cm, or optionally greater than or equal to 8 mS / cm and less than or equal to 12 mS / cm, or optionally less than or equal to 10 mS / cm.

[0044] The cationic component of the cyclic ammonium ionic liquid includes piperidine. Ions, pyrrolidine Ions or combinations thereof. Pyrrolidine Examples of ions include 1-methyl-1-ethylpyrrolidine. ([Py 12 ] + ), 1-propyl-1-methylpyrrolidine ([Py 13 ] +) and 1-butyl-1-methylpyrrolidine ([Py 14 ] + Piperidine Examples of ions include 1-propyl-1-methylpiperidine. ([PP 13 ] + ) and 1-butyl-1-methylpiperidine ([PP 14 ] + In various respects, the cationic component of the cyclic ammonium ionic liquid includes [Py]. 13 ] + .

[0045] The anionic components of the cyclic ammonium ionic liquid include arsenate ions, phosphate ions, sulfonamide ions, borate ions, chlorate ions, or combinations thereof. For example, the anionic components of the cyclic ammonium ionic liquid may include hexafluoroarsenate (AsF6). - ), hexafluorophosphate (PF6) - ), bis(fluorosulfonyl)imide (FSI), bis(trifluoromethyl)sulfonylimide (TFSI), tetrafluoroborate (LiBF4) - ), perchlorate (ClO4) - (or combinations thereof). In various respects, the anionic components of cyclic ammonium ionic liquids include bis(fluorosulfonyl)imide (FSI).

[0046] In embodiments where the electroactive material of the negative electrode 22 comprises silicon and the anionic component of an ethylene glycol dimethyl ether ionic liquid and / or the anionic component of a cyclic ammonium ionic liquid comprises bis(fluorosulfonyl)imide (N(FSO2)2-)(FSI), the N(SO2F)2- anions in the electrolyte 28 may participate in the in-situ formation of a solid electrolyte interface on the surface of the electroactive material of the negative electrode 22 during the initial and / or repeated cycling of the battery pack 20. The solid electrolyte interface formed on the electroactive material of the negative electrode 22 is electrically insulating and ionicly conductive, and when present, helps to prevent undesirable chemical reactions between the electrolyte 28 and the electroactive material of the negative electrode 22 during battery pack 20 cycling. During the formation of the solid electrolyte interface, the N(SO2F)2- anions in the electrolyte 28... - Anions can react with silicon and lithium in the electroactive material of negative electrode 22 and decompose to form inorganic compounds, such as lithium fluoride (LiF) and lithium silicate (Li). x SiO y Lithium silicide (Li) xSi) and combinations thereof. The inorganic decomposition products of N(SO2CF3)2- anions can be deposited on the electroactive material of the negative electrode 22 and form a solid electrolyte interface. Therefore, the solid electrolyte interface formed on the electroactive material of the negative electrode 22 can include lithium fluoride (LiF), lithium silicate (Li) and other similar materials. x SiO y Lithium silicide (Li) x Si) or combinations thereof.

[0047] In various embodiments, electrolyte 28 may be substantially free of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and substantially free of bis(trifluoromethanesulfonyl)imide N(SO₂CF₃)₂- anions. Not wishing to be bound by theory, it is believed that when silicon is used as the electroactive negative electrode material and the battery pack (e.g., battery pack 20) ​​cyclically uses lithium-ion batteries, the electrolyte may contain N(SO₂CF₃)₂. - When anions are present, N(SO2CF3)2 - Anions can decompose on the surface of the electroactive negative electrode material and form organic compounds (e.g., SO2CF3) during battery cycling. - and NSO2CF3 2- ), and the electrolyte (e.g., ionogel electrolyte 28) contains N(SO2F)2. - Compared to anion-based battery packs, this can lead to the formation of a relatively thick and unstable solid electrolyte interface on the surface of the electroactive negative electrode material. The formation of this relatively thick, unstable solid electrolyte interface containing organic compounds on the surface of the electroactive negative electrode material can result in rapid capacity decay.

[0048] In various embodiments, electrolyte 28 may be substantially free of non-aqueous aprotic organic solvents. Non-limiting examples of non-aqueous aprotic organic solvents that can be excluded from the composition of electrolyte 28 include cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), fluoroethylene carbonate (FEC), and vinylene carbonate (VC)); linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC)); aliphatic carboxylic acid esters (e.g., methyl formate, methyl acetate, and methyl propionate); lactones (e.g., γ-butyrolactone, γ-valerolactone, and / or δ-valerolactone); nitriles (...). For example, succinate, glutaronitrile and / or adiponitrile; sulfones (e.g., tetramethylene sulfone, ethylmethyl sulfone, vinyl sulfone, phenyl sulfone, 4-fluorophenyl sulfone, benzyl sulfone and / or sulfolane); aliphatic ethers (e.g., triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dimethoxypropane, 1,2-dimethoxyethane, 1,2-diethoxyethane and / or ethoxymethoxyethane); cyclic ethers (e.g., 1,4-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane); phosphate esters (e.g., triethyl phosphate and / or trimethyl phosphate); and combinations thereof.

[0049] like Figure 3 As shown, in various embodiments, the porous separator 26 may be at least partially defined by solid electrolyte particles 42, which may be disposed between the main surface 38 of the negative electrode 22 and the main surface 40 of the positive electrode 24. In embodiments where the porous separator 26 is at least partially defined by solid electrolyte particles 42, the electrolyte 28 may wet the open pores defined between the solid electrolyte particles 42 themselves, and may wet the gaps and / or pores defined between the solid electrolyte particles 42 and the electroactive materials of the negative electrode 22 and the positive electrode 24. In this way, the electrolyte 28 may create lithium-ion transport paths or "bridges" between the solid electrolyte particles 42 and the electroactive materials of the negative electrode 22 and the positive electrode 24. In various aspects, the electrolyte 28 may wet greater than or equal to 5% and less than or equal to 100% of the open pores defined between the solid electrolyte particles 42. In various aspects, the electrolyte 28 may wet approximately 80% of the open pores defined between the solid electrolyte particles 42. The solid electrolyte particles 42 may have an average particle size greater than or equal to about 1 μm and less than or equal to about 20 μm. The solid electrolyte particles 42 may include oxide solid electrolyte materials, metal-doped or anisovalent substituted oxide solid electrolyte materials, sulfide solid electrolyte materials, nitride solid electrolyte materials, hydride solid electrolyte materials, halide solid electrolyte materials, borate solid electrolyte materials, or combinations thereof.

[0050] The sulfide-based solid electrolyte material may be at least partially crystalline and includes lithium sulfide (Li₂S) and at least one element selected from phosphorus (P), tin (Sn), silicon (Si), germanium (Ge), boron (B), gallium (Ga), and aluminum (Al). For example, the sulfide-based solid electrolyte material may include Li₂S and at least one additional inorganic compound selected from phosphorus sulfide (P₂S₅), tin sulfide (SnS₂), silicon sulfide (SiS₂), germanium sulfide (GeS₂), boron sulfide (B₂S₃), gallium sulfide (Ga₂S₃), aluminum sulfide (Al₂S₃), lithium oxide (Li₂O), phosphorus oxide (P₂O₅), lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), arsenic sulfide (As₂S₅), and manganese sulfide (MnS). In various aspects, the solid electrolyte particles 42 may include binary sulfides, ternary sulfides, quaternary sulfides, or combinations thereof. In the aspect where the solid electrolyte particles 42 include binary sulfides, the solid electrolyte particles 42 may comprise lithium sulfide (Li2S) and at least one additional sulfide selected from phosphorus sulfide (P2S5), tin sulfide (SnS2), silicon sulfide (SiS2), germanium sulfide (GeS2), boron sulfide (B2S3), gallium sulfide (Ga2S3), and aluminum sulfide (Al2S3). For example, the solid electrolyte particles 42 may comprise Li2S-P2S5 (e.g., Li3PS4, Li7P3S). 11 and Li 9.6 P3S 12 The solid electrolyte particles 42 may contain binary sulfides such as Li2S-SnS2 (e.g., Li4SnS4), Li2S-SiS2, Li2S-GeS2, Li2S-B2S3, Li2S-Ga2S3, Li2S-P2S3, Li2S-Al2S3, or combinations thereof. In the case where the solid electrolyte particles 42 comprise ternary sulfides, the solid electrolyte particles 42 may contain lithium sulfide (Li2S) and at least two additional inorganic compounds selected from phosphorus sulfide (P2S5), tin sulfide (SnS2), silicon sulfide (SiS2), germanium sulfide (GeS2), aluminum sulfide (Al2S3), lithium oxide (Li2O), phosphorus oxide (P2O5), lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), and arsenic sulfide (As2S5). For example, solid electrolyte particles 42 may include Li2O-Li2S-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-GeS2 (e.g., Li 3.25 Ge 0.25 P 0.75 S4 and / or Li 10 GeP2S 12Li₂S-P₂S₅-LiX (where X is at least one of F, Cl, Br and I) (e.g., Li₆PS₅Br, Li₆PS₅Cl, L₇P₂S₈I and / or Li₄PS₄I), Li₂S-As₂S₅-SnS₂ (e.g., Li 3.833 Sn 0.833 As 0.166 S4), Li2S-P2S5-Al2S3, Li2S-LiX-SiS2 (where X is at least one of F, Cl, Br and I), 0.4LiI·0.6Li4SnS4, Li 11 Si2PS 12 In the case of ternary sulfides, or combinations thereof, the solid electrolyte particles 42 may comprise lithium sulfide (Li2S) and at least three additional inorganic compounds selected from phosphorus sulfide (P2S5), tin sulfide (SnS2), silicon sulfide (SiS2), lithium oxide (Li2O), phosphorus oxide (P2O5), lithium chloride (LiCl), lithium iodide (LiI), and manganese sulfide (MnS). For example, the solid electrolyte particles 42 may comprise Li2O-Li2S-P2S5-P2O5, Li... 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li7P 2.9 Mn 0.1 S 10.7 I 0.3 Li 10.35 [Sn 0.27 Si 1.08 ]P 1.65 S 12 , or combinations thereof, of quaternary sulfides. In all respects, solid electrolyte particles 42 may include lithium phosphorus sulfide Li6PS5Cl (LPSCl).

[0051] Examples of oxide-based solid electrolyte materials include garnet-type (e.g., Li7La3Zr2O) 12 ), perovskite type (e.g., Li), 3x La 2 / 3-x TiO3), NASICON type (e.g., Li) 1.4 Al 0.4 Ti 1.6 (PO4)3 and / or Li 1+x Al x Ge 2-x (PO4)3) and LISICON type (e.g., Li 2+2x Zn 1-xExamples of metal-doped or anisovalently substituted oxide solid electrolyte materials include Al or Nb-doped Li7La3Zr2O. 12 Sb-doped Li7La3Zr2O 12 Ga-substituted Li7La3Zr2O 12 LiSn2P3O substituted with Cr and V 12 And Al-substituted perovskites (e.g., Li) 1+x+y Al x Ti 2-x Si y P 3-y O 12 Examples of nitride-based solid electrolyte materials include Li3N, Li7PN4, and LiSi2N3. Examples of hydride-based solid electrolyte materials include LiBH4, LiBH4-LiX (X = Cl, Br, or I), LiNH2, Li2NH, LiBH4-LiNH2, and / or Li3AlH6. Examples of halide-based solid electrolyte materials include Li3YCl6, Li3InCl6, Li3YBr6, LiI, Li2CdCl4, Li2MgCl4, Li2CdI4, Li2ZnI4, and / or Li3OCl. Examples of borate-based solid electrolyte materials include Li2B4O7 and Li2O-B2O3-P2O5.

[0052] like Figure 4 As shown, in various embodiments, the porous separator 26 may be at least partially defined by a polymeric membrane 44, which may be sandwiched between the main surface 38 of the negative electrode 22 and the main surface 40 of the positive electrode 24. The polymeric membrane 44 has an open microporous structure comprising a plurality of open pores. In embodiments where the porous separator 26 is at least partially defined by the polymeric membrane 44, the electrolyte 28 may wet the open pores defined within the polymeric membrane 44. For example, the electrolyte 28 may wet greater than or equal to 5% and less than or equal to 100% of the open pores defined within the polymeric membrane 44. In various aspects, the electrolyte 28 may wet approximately 90% of the open pores defined within the polymeric membrane 44. The polymer film 44 may have a thickness of about 5 micrometers (μm) or greater, optionally about 10 μm or greater, or optionally about 20 μm or less than or equal to about 200 μm, optionally less than or equal to about 100 μm, or optionally less than or equal to about 50 μm.

[0053] The polymeric membrane 44 may comprise woven or nonwoven polymers. For example, the polymeric membrane 44 may comprise polyolefins (e.g., polyethylene, PE, polypropylene, PP, and / or polyacetylene), polyimide (PI), polyamide (PA) (e.g., poly(m-phenylene isophthalamide), PMIA), poly(tetrafluoroethylene) (PTFE), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene), polystyrene (e.g., lithium (4-styrene sulfonate)), polyetherimide (PEI) (e.g., bisphenol-acetone phthalic anhydride, BPADA, and / or p-phenylenediamine, pPD), cellulose, or combinations thereof. In various aspects, the polymeric membrane 44 may comprise a ceramic coating. Examples of ceramic materials that can be coated on the surface of the polymeric membrane 44 include SiO2, Al2O3, and combinations thereof.

[0054] In various aspects, the porous separator 26 may include solid electrolyte particles 42 and a polymer membrane 44 (not shown).

[0055] The negative electrode 22 is configured to store and release lithium ions to facilitate the charging and discharging of the battery pack 20, respectively. The negative electrode 22 may be in the form of a continuous porous layer disposed on the main surface of the negative electrode current collector 30. The negative electrode 22 comprises an electrochemically active (electroactive) material, a polymer binder, and optionally a conductive material. The electroactive material of the negative electrode 22 (electroactive negative electrode material) may be a particulate material, and the particles of the electroactive material of the negative electrode 22 may be mixed with the polymer binder and optionally the conductive material in the negative electrode 22. In this case, the particles of the electroactive material of the negative electrode 22 may define a plurality of open pores extending through the negative electrode 22.

[0056] The electroactive material of the negative electrode 22 is formulated to store and release lithium ions by undergoing a reversible redox reaction with lithium during the charging and discharging of the battery pack 20. Examples of electroactive negative electrode materials include lithium, lithium-based materials (e.g., alloys of lithium with silicon, aluminum, indium, and / or tin), carbon-based materials (e.g., graphite, activated carbon, carbon black, hard carbon, soft carbon, and / or graphene), silicon, silicon-based materials (e.g., alloys of silicon with lithium, tin, iron, aluminum, and / or cobalt), silicon oxides, silicon oxide-based materials (e.g., lithium silicon oxide), tin oxides, aluminum, indium, zinc, germanium, titanium oxides, lithium titanate, and combinations thereof. In various embodiments, the electroactive material of the negative electrode 22 may comprise a mixture of silicon and one or more carbon-based materials. The electroactive material of the negative electrode 22 may, by weight, constitute greater than or equal to 30%, optionally greater than or equal to 50%, or optionally greater than or equal to 70% and less than or equal to 98%, optionally less than or equal to 90%, or optionally less than or equal to 80% of the negative electrode 22.

[0057] The polymer binder of the negative electrode 22 is electrochemically inert and provides structural integrity for the negative electrode 22. Examples of polymer binders include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene propylene diene monomer (EPDM) rubber, styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), nitrile rubber (NBR), styrene-butadiene rubber (SBR), styrene-ethylene-butene-styrene copolymer (SEBS), polyacrylate, alginate, polyacrylic acid, and combinations thereof. The polymer binder of the negative electrode 22 may constitute greater than or equal to 5% by weight of the negative electrode 22, or optionally greater than or equal to 10% and less than or equal to 20%.

[0058] The optional conductive material of the negative electrode 22 is electrochemically inert and can facilitate the permeation of electrons through the negative electrode 22. Examples of conductive materials include carbon-based materials, metals (e.g., nickel), and / or conductive polymers. Examples of conductive carbon-based materials include carbon black (CB) (e.g., acetylene black), graphite, graphene (e.g., graphene nanosheets, GNP), graphene oxide, carbon nanotubes (CNTs), and / or carbon fibers (e.g., carbon nanofibers). Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, and / or polypyrrole. When present, the conductive material of the negative electrode 22 may constitute greater than or equal to 5% by weight of the negative electrode 22, or optionally greater than or equal to 10% and less than or equal to 30%.

[0059] The positive electrode 24 is configured to store and release lithium ions during the discharge and charging of the battery pack 20, respectively. The positive electrode 24 may be in the form of a continuous porous layer disposed on the main surface of the positive electrode current collector 32. The positive electrode 24 comprises an electroactive material (electroactive positive electrode material), a polymer binder, and optionally a conductive material. The electroactive material of the positive electrode 24 may be a particulate material, and the particles of the electroactive material of the positive electrode 24 may be mixed with the polymer binder and optionally the conductive material. The particles of the electroactive material of the positive electrode 24 may define a plurality of open pores extending through the positive electrode 24. The same polymer binder and / or conductive material disclosed above with respect to the negative electrode 22 may be used in substantially the same amount for the positive electrode 24.

[0060] The electroactive material of the positive electrode 24 is formulated to store and release lithium ions by undergoing a reversible redox reaction with lithium at a higher electrochemical potential than the electroactive material of the negative electrode 22, such that there is an electrochemical potential difference between the negative electrode 22 and the positive electrode 24. The electroactive material of the positive electrode 24 can include materials capable of lithium intercalation and deintercalation or materials capable of undergoing a conversion reaction with lithium. In aspects where the electroactive material of the positive electrode 24 includes an intercalation host material capable of reversible insertion or intercalation of lithium ions, the electroactive material of the positive electrode 24 can include lithium transition metal oxides. For example, the electroactive material of the positive electrode 24 can include layered lithium transition metal oxides represented by the formula LiMeO2 and / or Li2MeO3, layered lithium-rich transition metal oxides represented by the formula Li 1+x Me 1-x O2 (where 0 < x ≤ 0.33), olivine-type lithium transition metal oxides represented by the formula LiMePO4, monoclinic lithium transition metal oxides represented by the formula Li3Me2(PO4)3, spinel-type lithium transition metal oxides represented by the formula LiMe2O4, tavorite represented by one or both of the formula LiMeSO4F or LiMePO4F, or a combination thereof, where Me is a transition metal (e.g., Co, Ni, Mn, Fe, Al, V, or a combination thereof). In aspects where the electroactive material of the positive electrode 24 includes conversion materials, the electroactive material of the positive electrode 24 can include sulfur, selenium, tellurium, iodine, halides (e.g., fluorides or chlorides), sulfides (e.g., Li2S), selenides, tellurides, iodides, phosphides, nitrides, oxides, oxysulfides, oxyfluorides, sulfur fluorides, sulfur oxyfluorides, or lithium compounds and / or metal compounds thereof (e.g., compounds of iron, manganese, nickel, copper, and / or cobalt).

[0061] In embodiments where the porous separator 26 includes solid electrolyte particles 42, the negative electrode 22 and / or the positive electrode 24 can also include solid electrolyte particles (not shown). In such cases, the solid electrolyte particles 42 can account for greater than 0%, optionally greater than or equal to 10%, or optionally greater than or equal to 20%, and less than or equal to 50% by weight of the negative electrode 22 and / or the positive electrode 24.

[0062] The negative electrode current collector 30 and the positive electrode current collector 32 are conductive and provide electrical connections between the external circuit 36 and the negative electrode 22 and the positive electrode 24, respectively. In various aspects, the negative electrode current collector 30 and the positive electrode current collector 32 can be made of metal and can be in the form of a non-porous metal foil, a perforated metal foil, a porous metal mesh, or a combination thereof. The negative electrode current collector 30 can be made of copper, nickel, or an alloy thereof, stainless steel, or other suitable conductive materials. The positive electrode current collector 32 can be made of aluminum (Al) or other suitable conductive materials.

[0063] The foregoing description is merely exemplary in nature and is in no way intended to limit this disclosure, its application, or its use. The broad teachings of this disclosure can be implemented in various forms. Therefore, although this disclosure includes specific examples, its true scope should not be limited thereto, as other modifications will become apparent upon examination of the drawings, specification, and appended claims. It should be understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of this disclosure. Furthermore, although embodiments are described above as having certain features, any one or more features described with respect to any embodiment of this disclosure may be implemented in any other embodiment and / or combined with features of any other embodiment, even if such combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and substitution of one or more embodiments for each other remains within the scope of this disclosure. Unless expressly identified as an order of execution, any method steps, processes, and operations described herein should not be construed as necessarily requiring them to be performed in the specific order discussed or illustrated. It should also be understood that additional or alternative steps may be employed unless otherwise stated.

[0064] The phrase “at least one of A, B, and C” as used herein should be interpreted as referring to the logic of OR (A OR B OR C) using non-exclusive logic, and should not be interpreted as “at least one A, at least one B, and at least one C”. The term “and / or” as used herein includes combinations of one or more of the relevant enumerated items.

[0065] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms as used herein. The terms “comprising,” “including,” “covering,” and “having” are concurrent and thus specify the presence of the stated features, elements, compositions, steps, integers, operations, and / or components, but do not exclude the presence or inclusion of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Although the open-ended term “comprising” should be understood as a non-limiting term used to describe and claim the various embodiments described herein, in some respects it may be understood alternatively to more restrictive and limiting terms such as “consisting of” or “substantially consisting of.” Thus, for any given embodiment recounting a composition, material, component, element, feature, integer, operation, and / or method step, this disclosure also specifically includes embodiments consisting of or substantially consisting of such recounted compositions, materials, components, elements, features, integers, operations, and / or method steps. In the case of “consisting of…”, alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operating and / or method steps. In the case of “essentially composed of…”, any additional compositions, materials, components, elements, features, integers, operating and / or method steps that substantially affect the essential and novel characteristics are excluded from such embodiments. However, any compositions, materials, components, elements, features, integers, operating and / or method steps that do not substantially affect the essential and novel characteristics may be included in the embodiments.

[0066] Although the terms first, second, third, etc., may 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 stated. These terms may be used only to distinguish one step, element, component, region, layer, or section from another. Unless the context clearly indicates otherwise, terms such as “first,” “second,” and other numerical terms used herein do not imply order or sequence. Therefore, the first step, element, component, region, layer, or section discussed below may be referred to as the second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0067] As used herein, the terms “composition” and “material” are used interchangeably and refer generally to a substance that contains at least preferred chemical components, elements, or compounds, but may also contain additional elements, compounds, or substances, including trace impurities, unless otherwise stated. A composition or material “based on X” refers generally to a composition or material in which “X” is the single largest component by weight percentage (%). This can include compositions or materials having more than 50% by weight X, and compositions or materials having less than 50% by weight X, provided that X is the single largest component by weight of the composition or material. When a composition or material is referred to as “substantially free” of a substance, the composition or material may contain less than 5%, optionally less than 3%, optionally less than 1%, or optionally less than 0.1% of that substance by weight.

Claims

1. An electrolyte for a cyclic lithium-ion battery pack, the electrolyte comprising: Ethylene glycol dimethyl ether ionic liquids comprising substantially equimolar amounts of a cationic component and an anionic component, wherein the cationic component comprises lithium (Li). + A complex of ethylene glycol dimethyl ether, wherein the anionic component comprises arsenate ions, phosphate ions, sulfonamide ions, borate ions, chlorate ions, or combinations thereof; and A cyclic ammonium ionic liquid comprising a cationic component and an anionic component, wherein the cationic component includes piperidinium ions, pyrrolidineium ions, or combinations thereof, and the anionic component includes arsenate ions, phosphate ions, sulfonylimide ions, borate ions, chlorate ions, or combinations thereof. The electrolyte has a lithium concentration greater than or equal to 0.2 mol / L and less than or equal to 1.6 mol / L, and The electrolyte has a viscosity of greater than or equal to 10 mPa·s and less than or equal to 100 mPa·s at 25°C, and an ionic conductivity of greater than or equal to 4 mSiemens / cm and less than or equal to 10 mSiemens / cm.

2. The electrolyte according to claim 1, wherein at 25°C, the ethylene glycol dimethyl ether ionic liquid has a viscosity greater than 100 mPa·s, the cyclic ammonium ionic liquid has a viscosity less than 100 mPa·s, the ethylene glycol dimethyl ether ionic liquid has an ionic conductivity less than or equal to 2 mSiemens / cm, and the cyclic ammonium ionic liquid has an ionic conductivity greater than or equal to 4 mSiemens / cm.

3. The electrolyte according to claim 1, wherein the cationic component of the ethylene glycol dimethyl ether ionic liquid includes lithium (Li). + Complexes of ethylene glycol dimethyl ether with monoethylene glycol dimethyl ether, ethyl ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, butyl diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or combinations thereof, wherein the anionic component of the ethylene glycol dimethyl ether ionic liquid includes hexafluoroarsinate (AsF6-), hexafluorophosphate (PF6-), bis(fluorosulfonyl)imide (FSI), bis(trifluoromethyl)sulfonylimide (TFSI), tetrafluoroborate (LiBF4-), perchlorate (ClO4-), or combinations thereof, wherein the cationic component of the cyclic ammonium ionic liquid includes 1-methyl-1-ethylpyrrolidone ([Py 12 ] + ), 1-propyl-1-methylpyrrolidineonium ([Py 13 ] + ), 1-Butyl-1-methylpyrrolidone ([Py 14 ] + ), 1-propyl-1-methylpiperidinium ([PP) 13 ] + ), 1-Butyl-1-methylpiperidinium ([PP) 14 ] + (or combinations thereof), wherein the anionic component of the cyclic ammonium ionic liquid includes hexafluoroarsinate (AsF6-), hexafluorophosphate (PF6-), bis(fluorosulfonyl)imide (FSI), bis(trifluoromethyl)sulfonylimide (TFSI), tetrafluoroborate (LiBF4-), perchlorate (ClO4-), or combinations thereof.

4. The electrolyte according to claim 1, wherein the ethylene glycol dimethyl ether ionic liquid is formed from a mixture of ethylene glycol dimethyl ether and a lithium salt, and wherein the molar ratio of ethylene glycol dimethyl ether to lithium salt in the mixture is greater than or equal to 0.7:1 and less than or equal to 1.2:

1.

5. The electrolyte according to claim 1, wherein the cationic component of the ethylene glycol dimethyl ether ionic liquid includes lithium (Li). + The complex of ethylene glycol dimethyl ether with tetraethylene glycol dimethyl ether, wherein the anionic component of the ethylene glycol dimethyl ether ionic liquid includes bis(fluorosulfonyl)imide (FSI), and the cationic component of the cyclic ammonium ionic liquid includes 1-propyl-1-methylpyrrolidone ([Py 13 ] + ), and the anionic component of the cyclic ammonium ionic liquid includes bis(fluorosulfonyl)imide (FSI).

6. The electrolyte according to claim 1, wherein the volume ratio of ethylene glycol dimethyl ether ionic liquid to cyclic ammonium ionic liquid in the electrolyte is greater than or equal to 1:10 and less than or equal to 2:

1.

7. The electrolyte according to claim 1, wherein the electrolyte is substantially free of non-aqueous aprotic organic solvents.

8. A cyclic lithium-ion battery pack, the battery pack comprising: A negative electrode, comprising an electroactive negative electrode material, wherein the electroactive negative electrode material comprises silicon and sulfide-based solid electrolyte particles; A positive electrode, which is spaced apart from the negative electrode and includes an electroactive positive electrode material; A porous separator is disposed between the negative electrode and the positive electrode and has a plurality of open pores extending therethrough. The porous separator comprises a sulfide-based solid electrolyte material, which includes lithium sulfide (Li2S) and at least one element selected from phosphorus (P), tin (Sn), silicon (Si), germanium (Ge), boron (B), gallium (Ga) and aluminum (Al). as well as An electrolyte, which wets the open pores of the porous separator and is configured to provide a medium for the conduction of lithium ions through the porous separator and between the negative electrode and the positive electrode, the electrolyte comprising: Ethylene glycol dimethyl ether ionic liquids comprising substantially equimolar amounts of a cationic component and an anionic component, wherein the cationic component includes lithium (Li). + A complex of ethylene glycol dimethyl ether, wherein the anionic component comprises arsenate ions, phosphate ions, sulfonamide ions, borate ions, chlorate ions, or combinations thereof, and A cyclic ammonium ionic liquid comprising a cationic component and an anionic component, wherein the cationic component includes piperidinium ions, pyrrolidineium ions, or combinations thereof, and the anionic component includes arsenate ions, phosphate ions, sulfonylimide ions, borate ions, chlorate ions, or combinations thereof. The electrolyte has a lithium concentration greater than or equal to 0.2 mol / L and less than or equal to 1.6 mol / L, and The electrolyte has a viscosity of greater than or equal to 10 mPa·s and less than or equal to 100 mPa·s at 25°C, and an ionic conductivity of greater than or equal to 4 mSiemens / cm and less than or equal to 10 mSiemens / cm.

9. The battery pack according to claim 8, wherein the cationic component of the ethylene glycol dimethyl ether ionic liquid includes lithium (Li). + The complex of ethylene glycol dimethyl ether with tetraethylene glycol dimethyl ether, wherein the anionic component of the ethylene glycol dimethyl ether ionic liquid includes bis(fluorosulfonyl)imide (FSI), and the cationic component of the cyclic ammonium ionic liquid includes 1-propyl-1-methylpyrrolidone ([Py 13 ] + ), and the anionic component of the cyclic ammonium ionic liquid includes bis(fluorosulfonyl)imide (FSI).

10. The battery pack according to claim 8, wherein the volume ratio of ethylene glycol dimethyl ether ionic liquid to cyclic ammonium ionic liquid in the electrolyte is greater than or equal to 1:10 and less than or equal to 2:1.

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