Lithium metal battery cell, electrolyte, battery apparatus and electrical apparatus

Abstract

Provided are a lithium metal battery cell, an electrolyte, a battery apparatus and an electrical apparatus. The lithium metal battery cell comprises an electrode assembly and an electrolyte; the electrode assembly comprises a lithium metal negative electrode sheet; the electrolyte comprises a lithium salt and an ether solvent; the ether solvent comprises one or more of the structures shown as formula (1) and formula (2), wherein R1 and R6 each independently comprise any one of unsubstituted or halogen atom-substituted C1-C7 alkyl and C1-C7 alkenyl, R2, R4 and R5 each comprise any one of unsubstituted or halogen atom-substituted C1-C4 alkylene, R3 comprises any one of unsubstituted or halogen atom-substituted C3-C7 alkyl, and R1 and R3 are not simultaneously unsubstituted or halogen atom-substituted C3-C7 alkyl or C3-C7 alkenyl.

Description

Lithium metal battery cells, electrolytes, battery devices, and electrical devices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 202411479196.7, filed on October 22, 2024, entitled “Lithium metal battery cell, electrolyte, battery device and power supply device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of lithium metal battery cell technology, specifically relating to a lithium metal battery cell, electrolyte, battery device, and power supply device. Background Technology

[0004] With the application and promotion of lithium metal battery cells, their comprehensive performance has received increasing attention. For example, lithium metal battery cells need to simultaneously meet requirements such as long cycle life and high reliability. A lithium metal battery cell includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes and is one of the key factors affecting the performance of a lithium metal battery cell.

[0005] Therefore, in order to improve the overall performance of lithium metal battery cells, there is an urgent need to provide an electrolyte with good overall performance. Summary of the Invention

[0006] This application provides a lithium metal battery cell that produces less gas during electrochemical cycling, thereby improving the cycle life of the lithium metal battery cell; the electrolyte provided in this application can also improve the cycle life of the lithium metal battery cell. Battery devices and power-consuming devices incorporating this lithium metal battery cell have at least the above-mentioned beneficial effects.

[0007] In a first aspect, embodiments of this application provide a lithium metal battery cell, including an electrode assembly and an electrolyte; the electrode assembly includes a lithium metal negative electrode sheet; and includes an electrolyte; the electrolyte includes a lithium salt and an ether solvent, wherein the ether solvent includes one or more of the structures shown in formula (1) and formula (2):

[0008] R1 and R6 independently include any one of C1-C7 alkyl or C1-C7 alkenyl groups, whether unsubstituted or substituted with halogen atoms; R2, R4, and R5 include any one of C1-C4 alkylene groups, whether unsubstituted or substituted with halogen atoms; R3 includes any one of C3-C7 alkyl groups, whether unsubstituted or substituted with halogen atoms; R1 and R3 are not simultaneously unsubstituted or substituted with halogen atoms of either C3-C7 alkyl or C3-C7 alkenyl groups.

[0009] According to this embodiment, the ether solvent in the electrolyte includes the structure shown in formula (1), where R3 includes any one of C3 to C7 alkyl groups. This results in a longer chain length of R3 during the electrochemical cycling of the lithium metal battery cell, leading to less gas production and improved cycle life. The ether solvent in the electrolyte also includes the structure shown in formula (2), where R4 and R5 form a ring. This further reduces gas production during the electrochemical cycling of the lithium metal battery cell, thus improving cycle life.

[0010] In some optional embodiments, the ether solvent includes the structure shown in formula (1), where R1 includes any one of C1-C2 alkyl or C1-C2 alkenyl groups, R2 includes any one of C1-C4 alkylene groups, and R3 includes unsubstituted or halogen-substituted C3-C7 alkyl or C3-C7 alkenyl groups. The above-mentioned ether solvent has good solubility for lithium salts, which can adjust the viscosity and conductivity of the electrolyte, resulting in less gas production during the electrochemical cycling of the lithium metal battery cell and improving the cycle life of the lithium metal battery cell.

[0011] In some optional embodiments, the ether solvent includes the structure shown in formula (2), where R6 comprises any one of C1-C7 alkyl or C1-C7 alkenyl groups, R4 comprises any one of C1-C4 alkylene groups, and R5 comprises any one of unsubstituted or halogen-substituted C1-C4 alkylene groups. The above-mentioned ether solvent has good solubility for lithium salts, which can adjust the viscosity and conductivity of the electrolyte, resulting in less gas production during the electrochemical cycling of the lithium metal battery cell and improving the cycle life of the lithium metal battery cell.

[0012] In some alternative embodiments, R6 includes the structure shown in any one of formulas (I-1) to (I-10);

[0013] in, As a connecting point, R7 includes a connecting bond and any one of C1 to C4 alkylene groups. R1 includes the structure shown in any one of formulas (I-1) to (I-10), which can improve the ability of electrolytes containing this ether solvent to dissolve lithium salts and improve the overall performance of lithium metal battery cells.

[0014] In some optional embodiments, R1 includes the structure shown in any one of formula (I-1) or formula (I-3), and R3 includes any one of the above structures from formula (I-4) to (I-10). Therefore, in the ether solvent shown in formula (1), the gas production of the electrolyte during the electrochemical cycling process of the lithium metal battery cell can be reduced, thereby improving the cycle life of the lithium metal battery cell.

[0015] In some optional embodiments, the ether solvent includes the structure of formula (1), and the ether solvent includes the structure shown in any one of formulas (J-1) to (J-9):

[0016] In some optional embodiments, the ether solvent comprises the structure of formula (2), and the ether solvent comprises the structure shown in any one of formulas (H-1) to (H-8):

[0017] According to the embodiments of this application, the above-mentioned ether solvents in lithium metal batteries can reduce the amount of gas generated by the reaction between the electrolyte and the negative electrode, thereby further improving the battery cycle life.

[0018] In some optional embodiments, the ether solvent includes the structure of formula (2), and the ether solvent includes the structure shown in any one of formulas (K-1) to (K-17):

[0019] In some optional embodiments, the molar ratio of lithium salt to ether solvent is 1:(1-4). When the molar ratio of lithium salt to ether solvent is within the above range, the electrolyte exhibits good conductivity, effectively dissolving the lithium salt and enhancing the ionic conductivity of the electrolyte, thereby improving the kinetic performance of the lithium metal battery. The ether solvent possesses high chemical stability or good oxidation resistance, and is not easily decomposed during the charge and discharge process of the lithium metal battery, thus maintaining the long-term stability of the electrolyte and extending the cycle life of the lithium metal battery.

[0020] In some optional embodiments, the molar ratio of lithium salt, ether solvent, and diluent is 1:(1-4):(0.5-2). Maintaining this molar ratio within the above range can reduce side reactions and provide sufficient active ions, thereby improving the cycle capacity retention of lithium metal battery cells. It can also optimize the interfacial characteristics between the electrode and the electrolyte, enhancing the interfacial stability of the battery and increasing the lifespan of lithium metal battery cells.

[0021] In some optional embodiments, the electrolyte further includes a diluent comprising one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl (TFE), 1-(1,1,2,2-tetrafluoroethoxy)propane (TFEPE), 1,1,2,2-tetrafluoroethyl ether (ETE), bis(2,2,2-trifluoroethyl) ether (BTFE); or benzene (BZ) and anisole. The above-mentioned diluents can dilute ether solvents and adjust the viscosity and other properties of the electrolyte.

[0022] In some optional embodiments, the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0023] In some optional embodiments, the conductivity of the electrolyte is from 0.5 mS / cm to 10 mS / cm, optionally from 2 mS / cm to 8 mS / cm. This conductivity can reduce the internal resistance of the lithium metal battery cell, increase the charge transfer rate, improve kinetic performance, and enable the lithium metal battery cell to maintain high energy output at high current densities. This conductivity also helps reduce uneven current distribution and improve the cycle life of the lithium metal battery cell.

[0024] In some optional embodiments, the viscosity of the electrolyte is from 2 mPa·s to 20 mPa·s, optionally from 8 mPa·s to 15 mPa·s. Electrolyte viscosity within this range helps to increase the lithium-ion diffusion coefficient, thereby accelerating charge transfer and improving the kinetic performance of lithium metal battery cells. Electrolytes with the above-mentioned viscosities also help to balance the lithium deposition process, reduce dendrite formation, and improve the stability and cycle life of lithium metal battery cells.

[0025] In some alternative embodiments, the electrode assembly further includes a separator and a positive electrode stacked with the lithium metal negative electrode.

[0026] Secondly, embodiments of this application provide an electrolyte for lithium metal battery cells, the electrolyte comprising lithium salt and ether solvent, wherein the ether solvent comprises one or more of the structures shown in formula (1) and formula (2):

[0027] R1 and R6 independently include any one of C1-C7 alkyl or C1-C7 alkenyl groups, whether unsubstituted or substituted with halogen atoms; R2, R4, and R5 include any one of C1-C4 alkylene groups, whether unsubstituted or substituted with halogen atoms; R3 includes any one of C3-C7 alkyl groups, whether unsubstituted or substituted with halogen atoms; R1 and R3 are not simultaneously unsubstituted or substituted with halogen atoms of either C3-C7 alkyl or C3-C7 alkenyl groups.

[0028] According to this embodiment, the ether solvent in the electrolyte includes the structure shown in formula (1), where R3 includes any one of C3 to C7 alkyl groups. This results in a longer chain length of R3 during the electrochemical cycling of the lithium metal battery cell, leading to less gas production and improved cycle life. The ether solvent in the electrolyte also includes the structure shown in formula (2), where R4 and R5 form a ring. This further reduces gas production during the electrochemical cycling of the lithium metal battery cell, thus improving cycle life.

[0029] Thirdly, embodiments of this application provide a battery device, including a lithium metal battery cell of the first aspect or a battery cell prepared using an electrolyte of the second aspect. The battery device of this application includes either the lithium metal battery cell of the first aspect or a lithium metal battery cell prepared using the electrolyte of the second aspect, and therefore possesses at least the advantages of either a lithium metal battery cell or an electrolyte.

[0030] Fourthly, embodiments of this application provide an electrical device that includes the battery device of the third aspect. The electrical device of this application includes the battery device of the third aspect, and therefore has at least the advantages corresponding to the battery device. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0032] Figure 1 shows a schematic diagram of one embodiment of the lithium metal battery cell of this application.

[0033] Figure 2 shows an exploded schematic diagram of one embodiment of the lithium metal battery cell shown in Figure 1.

[0034] Figure 3 shows an overall schematic diagram of a battery pack according to one embodiment of this application.

[0035] Figure 4 shows an exploded view of a battery pack according to one embodiment of this application.

[0036] Figure 5 shows a schematic diagram of one embodiment of an electrical device that uses a lithium metal battery cell as a power source, incorporating the present application.

[0037] The reference numerals in the attached diagram are explained as follows: 1. Battery pack, 2. Upper casing, 3. Lower casing, 4. Battery module, 5. Lithium metal battery cell.

[0038] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0039] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the lithium metal battery cell, electrolyte, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0040] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0042] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0043] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] Throughout this application, substituents of compounds are disclosed by groups or ranges. It is expressly intended that such descriptions include each individual sub-combination of members of these ranges. For example, it is expressly intended that the term "C1-C7 alkyl" individually discloses alkyl groups of C1, C2, C3, C4, C5, C6, C7, C1-C7, C2-C7, C3-C7, C4-C7, C5-C7, C6-C7, C1-C6, C2-C6, C3-C6, C4-C6, C5-C6, C1-C5, C2-C5, C3-C5, C4-C5, C1-C4, C2-C4, C3-C4, C1-C3, and C2-C3. Unless otherwise stated, the term "alkyl" encompasses both straight-chain alkyl and branched-chain alkyl groups. For example, the term "C1-C4 alkylene" separately discloses alkylene groups of C1, C2, C3, C4, C1-C4, C2-C4, C3-C4, C2-C3, and C1-C3. Unless otherwise stated, the term "alkylene" covers both straight-chain alkyl and branched-chain alkyl groups.

[0045] Unless otherwise specified, in this application, the term "active ion" refers to ions that can be inserted and extracted back and forth between the positive and negative electrodes of a lithium metal battery cell, including but not limited to lithium ions.

[0046] In this application, "multiple" or "more than" refers to two or more items (including two). In this application, "several items" or "multiple items" refers to two or more items (including two).

[0047] The battery device mentioned in the embodiments of this application may include one or more lithium metal battery cells as a single physical module to provide higher voltage and capacity. For example, the battery device mentioned in this application may include lithium metal battery cells, battery modules, or battery packs.

[0048] In some alternative embodiments, the battery device can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc. The battery device mentioned in the embodiments of this application may include one or more lithium metal battery cell assemblies for providing voltage and capacity. A lithium metal battery cell assembly may include multiple lithium metal battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0049] In some alternative embodiments, a lithium metal battery cell assembly is typically formed by arranging multiple lithium metal battery cells; as an example, a lithium metal battery cell assembly can be a battery module, which is formed by arranging and fixing multiple lithium metal battery cells into a single module. As an example, a battery module can be formed by bundling multiple lithium metal battery cells together with cable ties.

[0050] In some alternative embodiments, the battery device may be a battery pack, which may include a housing and one or more lithium metal battery cell assemblies housed within the housing. In some alternative embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0051] As an example, a lithium metal battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0052] As an example, lithium metal battery cell assemblies can also be housed in a housing by directly fixing multiple lithium metal battery cells to the housing.

[0053] A lithium metal battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A lithium metal battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited to this. Figure 1 shows a cuboid lithium metal battery cell 5 as an example.

[0054] When there are multiple lithium metal battery cells, the multiple lithium metal battery cells are connected in series, parallel, or mixed through a busbar. In some optional embodiments, the battery can be a battery module; when there are multiple lithium metal battery cells, the multiple lithium metal battery cells are arranged and fixed to form a battery module.

[0055] In some optional embodiments, lithium metal battery cells can be assembled into a battery module. The number of lithium metal battery cells in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 2 is a schematic diagram of a battery module 4 as an example. As shown in Figure 2, in the battery module 4, multiple lithium metal battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Furthermore, the multiple lithium metal battery cells 5 can be fixed in place using fasteners.

[0056] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple lithium metal battery cells 5 are received.

[0057] In some alternative embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0058] Figures 3 and 4 are schematic diagrams of a battery pack 1 as an example. As shown in Figures 3 and 4, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 and forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0059] The lithium metal battery cells provided in the embodiments of this application can be secondary batteries, primary batteries, etc. A secondary battery is a lithium metal battery cell that can be recharged after discharge to activate the active materials and continue to be used.

[0060] The lithium metal battery cell provided in this application includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode and a negative electrode. The negative electrode can be a lithium metal negative electrode. The electrode assembly can be a wound structure or a stacked structure; this application does not limit this. In some optional embodiments, the electrode assembly further includes a separator disposed between the positive and negative electrode. In some optional embodiments, the separator is a separator membrane. This application does not have a particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. In some optional embodiments, the electrode assembly may not have a separator, and the electrolyte may function as a separator.

[0061] Lithium metal battery cells may also include an outer packaging, which can be used to encapsulate electrode components and electrolytes. The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a soft pack, such as a pouch. The soft pack material can be plastic, such as one or more of aluminum-plastic film, polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). The negative electrode of a lithium metal battery cell is generally made of lithium metal, which has strong reducing properties and easily reduces ether-based electrolytes, producing gas. Taking commonly used dimethyl glycol ether (DME) as an example, the CO bond in DME breaks, yielding a CH3· radical. This radical is unstable and reacts with DME to produce a hydrogen atom to form methane (CH4).

[0062] In related technologies, high lithium salt concentrations are used. However, as the number of cycles increases, the lithium salt is continuously consumed, generating free solvent molecules. In the later stages of electrochemical cycling of lithium metal battery cells, the reaction between the electrolyte and lithium metal intensifies, leading to severe gas production in the later stages of cycling. Using fluorinated modified ether solvents in the electrolyte also has certain drawbacks, such as the high cost and high toxicity of fluorinated ether synthesis.

[0063] This application provides a lithium metal battery cell in which the electrolyte reacts with lithium metal, producing little or no gas and improving the cycle life of the lithium metal battery.

[0064] In a first aspect, embodiments of this application provide a lithium metal battery cell, including an electrode assembly and an electrolyte; the electrode assembly includes a lithium metal negative electrode. In some optional embodiments, the electrode assembly further includes a separator and a positive electrode stacked with the lithium metal negative electrode.

[0065] In some alternative embodiments, the electrolyte comprises a lithium salt and an ether solvent, wherein the ether solvent comprises one or more of the structures shown in formulas (1) and (2):

[0066] R1 and R6 independently include any one of C1-C7 alkyl or C1-C7 alkenyl groups, whether unsubstituted or substituted with halogen atoms; R2, R4, and R5 include any one of C1-C4 alkylene groups, whether unsubstituted or substituted with halogen atoms; R3 includes any one of C3-C7 alkyl groups, whether unsubstituted or substituted with halogen atoms; R1 and R3 are not simultaneously unsubstituted or substituted with halogen atoms of either C3-C7 alkyl or C3-C7 alkenyl groups.

[0067] According to this embodiment, the ether solvent in the electrolyte includes the structure shown in formula (1), where R3 includes any one of C3 to C7 alkyl groups. This results in a longer chain length of R3 during the electrochemical cycling of the lithium metal battery cell, leading to less gas production and improved cycle life. The ether solvent in the electrolyte also includes the structure shown in formula (2), where R4 and R5 form a ring with oxygen atoms. This further reduces gas production during the electrochemical cycling of the lithium metal battery cell, thus improving cycle life.

[0068] R1 and R3 not being simultaneously C3-C7 alkyl or C3-C7 alkenyl can be understood as R1 and R3 not being simultaneously groups containing 3 to 7 carbon atoms. This group can be alkyl at the same time or one can be alkyl and the other can be alkenyl.

[0069] Halogen atoms can be understood as fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc., with fluorine atoms being a possible choice.

[0070] In some alternative embodiments, R6 includes the structure shown in any one of formulas (I-1) to (I-10);

[0071] in, For the connection point, R7 includes any one of the following: a connecting bond, or a C1 to C4 alkylene group.

[0072] According to the embodiments of this application, the ability of an electrolyte containing the ether solvent to dissolve lithium salts can be improved, providing solvated lithium ions and improving the overall performance of lithium metal battery cells.

[0073] In some optional embodiments, R1 includes the structure shown in any one of formula (I-1) or formula (I-3), and R3 includes the structure shown in any one of formulas (I-4) to (I-10). Therefore, in the ether solvent shown in formula (1), the gas production of the electrolyte during the electrochemical cycling process of the lithium metal battery cell can be reduced, thereby improving the cycle life of the lithium metal battery cell.

[0074] In some optional embodiments, the ether solvent includes the structure shown in formula (1), where R1 includes any one of C1-C2 alkyl or C1-C2 alkenyl groups, R2 includes any one of C1-C4 alkylene groups, and R3 includes unsubstituted or halogen-substituted C3-C7 alkyl or C3-C7 alkenyl groups. The above-mentioned ether solvent has good solubility for lithium salts, which can adjust the viscosity and conductivity of the electrolyte, resulting in less gas production during the electrochemical cycling of the lithium metal battery cell and improving the cycle life of the lithium metal battery cell.

[0075] In some optional embodiments, the ether solvent includes the structure shown in formula (2), where R6 comprises any one of C1-C7 alkyl or C1-C7 alkenyl groups, R4 comprises any one of C1-C4 alkylene groups, and R5 comprises any one of unsubstituted or halogen-substituted C1-C4 alkylene groups. The above-mentioned ether solvent has good solubility for lithium salts, which can adjust the viscosity and conductivity of the electrolyte, resulting in less gas production during the electrochemical cycling of the lithium metal battery cell and improving the cycle life of the lithium metal battery cell.

[0076] In some optional embodiments, the ether solvent includes the structure of formula (1), and the ether solvent includes the structure shown in any one of formulas (J-1) to (J-9):

[0077] In some optional embodiments, the ether solvent comprises the structure of formula (2), and the ether solvent comprises the structure shown in any one of formulas (H-1) to (H-8):

[0078] According to the embodiments of this application, the above-mentioned ether solvents can reduce the amount of gas generated by the reaction with the negative electrode in lithium metal batteries, thereby further improving the cycle life of the battery.

[0079] In some optional embodiments, the ether solvent includes the structure of formula (2), and the ether solvent includes the structure shown in any one of formulas (K-1) to (K-17):

[0080] In some optional embodiments, the molar ratio of lithium salt to ether solvent is 1:(1-4). Optionally, the molar ratio of lithium salt to ether solvent can be any value or a range thereof from 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:3.6, 1:3.7, 1:3.8, 1:3.9, and 1:4. When the molar ratio of lithium salt to ether solvent is within the above range, the electrolyte has good conductivity, can effectively dissolve lithium salt, enhance the ionic conductivity of the electrolyte, and can improve the kinetic performance of lithium metal batteries; the ether solvent has high chemical stability or good oxidation resistance, and is not easily decomposed during the charge and discharge process of lithium metal batteries, which can maintain the long-term stability of the electrolyte and extend the cycle life of lithium metal batteries.

[0081] In some optional embodiments, the molar ratio of lithium salt, ether solvent, and diluent is 1:(1-4):(0.5-2). Optionally, the molar ratio of lithium salt to ether solvent can be any value or a range of combinations thereof from 1:1:0.5, 1:1:1, 1:1:2, 1:1.2:2, 1:3:2, 1:1.4:1, 1:1.5:1, 1:2:0.5, 1:2:1, 1:2:2, 1:2.5:0.5, 1:3:0.5, 1:3.5:1, 1:3.6:1, 1:3.7:1, 1:3.8:1, 1:3.9:1, and 1:4:2. When the molar ratio of lithium salt, ether solvent, and diluent is within the above range, side reactions can be reduced and sufficient active ions can be provided, thereby improving the cycle capacity retention of lithium metal battery cells. It can also optimize the interfacial characteristics between the electrode and the electrolyte, enhance the interfacial stability of the battery, and improve the service life of lithium metal battery cells.

[0082] In some optional embodiments, the electrolyte further includes a diluent, comprising one or more of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl (TFE), 1-(1,1,2,2-tetrafluoroethoxy)propane (TFEPE), 1,1,2,2-tetrafluoroethyl ether (ETE), bis(2,2,2-trifluoroethyl) ether (BTFE), benzene (BZ), and anisole. The above-mentioned diluents can impart suitable viscosity to the electrolyte, further improving the kinetic performance of the lithium-ion battery cell.

[0083] In some optional embodiments, the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0084] In some optional embodiments, the conductivity of the electrolyte is from 0.5 mS / cm to 10 mS / cm; optionally, it is from 2 mS / cm to 8 mS / cm.

[0085] Optionally, the conductivity of the electrolyte can be any value or a range thereof from 0.5 mS / cm, 1.0 mS / cm, 1.5 mS / cm, 2.0 mS / cm, 2.5 mS / cm, 3.0 mS / cm, 3.5 mS / cm, 4.0 mS / cm, 4.5 mS / cm, 5.0 mS / cm, 5.5 mS / cm, 6.0 mS / cm, 6.5 mS / cm, 7.0 mS / cm, 7.5 mS / cm, 8.0 mS / cm, 8.5 mS / cm, 9.0 mS / cm, 9.5 mS / cm, and 10.0 mS / cm. The conductivity of the electrolyte reflects the migration ability of lithium ions in the electrolyte. The above-mentioned conductivity can reduce the internal resistance of lithium metal battery cells, improve the charge transfer rate, improve kinetic performance, and enable lithium metal battery cells to maintain high energy output at high current densities. The aforementioned conductivity helps reduce uneven current distribution and improve the cycle life of lithium metal battery cells.

[0086] The conductivity of the electrolyte can be obtained by testing with a conductivity meter. For example, a suitable amount of electrolyte can be taken, divided into three equal portions, and then the conductivity of each sample can be measured using a conductivity meter at 25°C. The average of the test results is then taken as the conductivity of the electrolyte. A DDS-307 conductivity meter can be used as the testing instrument.

[0087] In some optional embodiments, the viscosity of the electrolyte is from 2 mPa·s to 20 mPa·s, and optionally from 8 mPa·s to 15 mPa·s.

[0088] Optionally, the viscosity of the electrolyte can be any value or a range thereof from 2.0 mPa·s, 2.5 mPa·s, 3.0 mPa·s, 3.5 mPa·s, 4.0 mPa·s, 4.5 mPa·s, 5.0 mPa·s, 5.5 mPa·s, 6.0 mPa·s, 6.5 mPa·s, 7.0 mPa·s, 7.5 mPa·s, 8.0 mPa·s, 8.5 mPa·s, 9.0 mPa·s, 9.5 mPa·s, 10.0 mPa·s, 11.0 mPa·s, 12.0 mPa·s, 13.0 mPa·s, 14.0 mPa·s, 15.0 mPa·s, 16.0 mPa·s, 17.0 mPa·s, 18.0 mPa·s, 19.0 mPa·s, and 20.0 mPa·s. The viscosity of the electrolyte affects the diffusion rate of lithium ions within the electrolyte. Electrolyte viscosities within the aforementioned range help increase the lithium ion diffusion coefficient, thereby accelerating charge transfer and improving the kinetic performance of lithium metal battery cells. Electrolytes with these viscosities also help balance the lithium deposition process, reduce dendrite formation, and improve the stability and cycle life of lithium metal battery cells.

[0089] The viscosity of the electrolyte can be tested using a viscometer. When the rotor rotates continuously at a constant speed in the sample, the shear force it experiences causes the spring to generate torque. The torque is proportional to the viscosity, thus yielding the viscosity value of the sample.

[0090] As an example, the viscosity of the electrolyte can be tested as follows: Under ambient humidity <80%, take a 30mL sample and keep it at a constant temperature of 25℃ in a water bath for at least 30 minutes. Place the rotor (e.g., a No. 18 rotor) into the sample cup, add the sample to about 0.3cm from the rim, start the connected viscometer, select a speed of 70RPM and rotate for 5 minutes to obtain the viscosity value. Ten data points can be collected during the test, and the average value is taken. The testing instrument can be a Bollerfeld DV-2TLV viscometer.

[0091] The components and their contents in the electrolyte can be determined using methods conventional in the field. For example, they can be detected using gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), inductively coupled plasma optical emission spectrometry (ICP-OES), infrared spectroscopy, Raman spectroscopy, nuclear magnetic resonance, and other methods.

[0092] As an example, compounds in an electrolyte can be identified using infrared spectroscopy, such as the characteristic peak of the sulfur-oxygen double bond in sulfoxide compounds at 1060 cm⁻¹. -1 -1040cm -1 Within the specified range, high-resolution gas chromatography-high-resolution mass spectrometry (HPLC-MS / MS) can separate different components in the electrolyte and obtain high-precision molecular weights, thereby determining the atomic composition; then, the specific molecular structure of each component can be confirmed by nuclear magnetic resonance (NMR) spectroscopy results.

[0093] As an example, ion chromatography (IC) can be used to test the content of electrolyte salts in an electrolyte solution, while gas chromatography-mass spectrometry (GC-MS) can be used to test the content of various components in an organic solvent.

[0094] Electrolyte can be obtained by sampling and analyzing during the preparation process, or by disassembling and centrifuging the prepared lithium metal battery cells after discharge.

[0095] The preparation methods for electrolytes are well known. For example, an electrolyte salt (lithium salt), a solvent, and optional additives can be mixed evenly to obtain an electrolyte. There are no particular restrictions on the order in which the materials are added during the preparation process; they can be added simultaneously or in batches.

[0096] [Positive electrode plate]

[0097] In some alternative embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer comprising a positive active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0098] The type of positive electrode active material can be selected according to the type of lithium metal battery cell, and this application embodiment does not limit this.

[0099] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0100] As an example, the positive current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0101] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0102] Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0103] During the charging and discharging process, lithium (Li) undergoes insertion / extraction and consumption within a single battery cell, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before material addition. As the positive electrode active material is applied to the battery cell, the molar Li content changes after charge-discharge cycles. Similarly, the molar oxygen (O) content in the examples of positive electrode active materials in this disclosure is only a theoretical value. Lattice oxygen release causes changes in the molar O content, leading to fluctuations in the actual molar O content.

[0104] In some alternative embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, a positive electrode active material is filled and / or deposited within the foamed metal.

[0105] In some optional embodiments, the positive electrode film layer may also optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0106] In some optional embodiments, the positive electrode film layer may also optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0107] In some alternative embodiments, the positive current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0108] The positive electrode film can be formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0109] [Lithium metal anode sheet]

[0110] In some optional embodiments, the lithium metal negative electrode sheet may include a negative current collector and a first metal layer disposed on at least one surface of the negative current collector, wherein the metal element in the first metal layer may include one or more of alkali metal elements and alkaline earth metal elements.

[0111] In some alternative embodiments, the metal material in the first metal layer may include one or more of elemental lithium and lithium alloys.

[0112] Lithium alloys can be alloys formed from metallic lithium with other metallic or non-metallic elements. For example, other metallic elements in lithium alloys may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements may include one or more of boron, carbon, and silicon.

[0113] In some optional embodiments, the negative electrode current collector may include a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, aluminum mesh, copper foam, nickel foam, and aluminum foam. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0114] [Isolation membrane]

[0115] The lithium metal battery cell may also include a separator. The separator is disposed between the positive and negative electrodes, primarily serving to prevent internal short circuits. This application does not impose any particular limitation on the type of separator; any known porous membrane with good chemical and mechanical stability can be selected.

[0116] In some optional embodiments, the separator can be a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0117] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0118] In some alternative embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0119] The preparation methods of lithium metal battery cells are well known. In some optional embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a lithium metal battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a lithium metal battery cell is obtained. Multiple lithium metal battery cells can be further connected in series, parallel, or in a mixed configuration to form a battery module. Multiple lithium metal battery cell modules can also be connected in series, parallel, or in a mixed configuration to form a battery pack. In some optional embodiments, multiple lithium metal battery cells can also be directly assembled into a battery pack.

[0120] Electrical appliances

[0121] This application provides an electrical device, including the battery device described above.

[0122] Lithium metal battery cells can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices can be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0123] Electrical devices can be selected from lithium metal battery cells, lithium metal battery cell modules, or lithium metal battery cell packs according to their usage requirements.

[0124] Figure 5 is a schematic diagram of an example electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this device, lithium metal battery packs or lithium metal battery modules can be used.

[0125] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can utilize lithium metal battery cells as their power source.

[0126] Example

[0127] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0128] Example 1

[0129] Electrolyte preparation:

[0130] 1 mol of lithium salt (lithium bisfluorosulfonylimide LiFSI) was dissolved in 2 mol of ether solvent, the ether solvent being the compound shown in formula (K-3), to obtain the electrolyte.

[0131] Preparation of lithium metal batteries:

[0132] Positive electrode sheet: The positive electrode active material lithium nickel cobalt manganese oxide (NCM811), conductive agent acetylene black, and binder polyvinylidene fluoride are mixed in a mass ratio of 8:1:1. N-methylpyrrolidone solvent is added and stirred until the system is homogeneous to obtain the positive electrode slurry. The positive electrode slurry is uniformly coated on both sides of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. It is then cut into 40mm × 50mm rectangles to serve as the positive electrode sheet, with a positive electrode surface capacity of 3.5 mAh / cm². 2 .

[0133] The areal capacity of the positive electrode is calculated as: Affect Capacity of the Positive Electrode / Area of ​​the Positive Electrode. At 25°C, a lithium metal battery cell is allowed to stand for 5 minutes, then discharged at a constant current of 0.1C to 2.8V. After standing for 5 minutes, it is charged at a constant current of 0.1C to 4.25V, then charged at a constant voltage of 4.25V to a current of 0.05C. After standing for 5 minutes, it is discharged at a constant current of 0.1C to 2.8V. The discharge capacity at this point is recorded as Q1, the capacity of the lithium metal battery cell. The areal capacity of the positive electrode is calculated as: Affect Capacity of the Positive Electrode = Q1 / Area of ​​the Positive Electrode. The area of ​​the electrode is calculated by measuring its length and width.

[0134] Lithium metal negative electrode sheet: A 50μm thick lithium foil is coated onto a 12μm thick copper foil by single-sided rolling, and then cut into a 41mm×51mm rectangle for use as a negative electrode sheet.

[0135] Preparation of the separator: A polyethylene film with a thickness of 13 μm was used as the separator.

[0136] Assembly of lithium metal batteries: The lithium metal batteries are arranged in the following order: negative electrode - separator - positive electrode - separator - negative electrode. The lithium foil is placed on the separator side and wrapped in an aluminum-plastic film bag to form a stacked dry cell. The previously prepared electrolyte is injected at an injection rate of 2.0 g / Ah. The aluminum-plastic film bag is then vacuum-sealed to obtain the stacked battery. After standing at room temperature for at least 6 hours, cycle testing begins.

[0137] Examples 2-4

[0138] The preparation method is similar to that in Example 1, except that the electrolyte is different and the molar amount of ether solvent added to the electrolyte is different, resulting in a different molar ratio of lithium salt (lithium bisfluorosulfonylimide LiFSI) to ether solvent, as shown in Table 1.

[0139] Examples 5-10

[0140] The preparation method is similar to that in Example 1, except that the electrolyte is different and the types of ether solvents are different, as shown in Table 1.

[0141] Examples 11-13

[0142] The preparation method is similar to that in Example 1, except that the electrolyte is different, and a diluent is added, resulting in different molar amounts of ether solvent, lithium salt, and diluent, as shown in Table 1.

[0143] Comparative Example 1

[0144] The preparation method is similar to that in Example 1, except that the electrolyte is different; the ether solvent shown in formula (K-3) is replaced with an equal mass of dimethyl ethylene glycol ether (DME). See Table 1.

[0145] Comparative Example 2

[0146] The preparation method is similar to that in Example 13, except that the electrolyte is different; the ether solvent shown in formula (K-3) is replaced with an equal mass of dimethyl ethylene glycol ether (DME). See Table 1.

[0147] Test section

[0148] The test results for the electrolyte and lithium metal battery cells were obtained using three parallel samples, and the results of the parallel samples were similar.

[0149] 1) Capacity of a single lithium metal battery cell: At 25°C, the single lithium metal battery cell is left to stand for 5 minutes. After standing for 5 minutes, it is charged at a constant current of 0.1C to 4.25V, and then charged at a constant voltage of 4.25V to a current of 0.05C. After standing for 5 minutes, it is discharged at a constant current of 0.1C to 2.8V. The discharge capacity at this time is recorded as the capacity Q1 of the single lithium metal battery cell.

[0150] 2) Cycle life test of lithium metal battery cells: At an ambient temperature of 25℃, the prepared lithium metal battery cells were charged and discharged at a rate of 0.2C, with cut-off voltages of 4.25V and 2.8V. When the discharge capacity after cycling decayed to 80% of the first discharge capacity, the number of cycles was recorded. This number of cycles is considered the cycle life of the lithium metal battery cell.

[0151] 3) Method for detecting gas production of lithium metal battery cells: Following the silicone oil removal method, at 25°C, the lithium metal battery cells were left to stand for 5 minutes and discharged at a constant current of 0.1C to 2.8V; after standing for 5 minutes, they were charged at a constant current of 0.1C to 4.25V, and then charged at a constant voltage of 4.25V to a current of 0.05C; the fully charged cells were placed in a silicone oil device and stabilized for 6 hours, then heated to 60°C and stabilized for 3 hours. The initial silicone oil level V1 (mL) was recorded. After storing at 25°C for 15 days, the silicone oil level V2 (mL) was recorded. The gas production was (V2-V1) / Q1.

[0152] The test results are shown in Table 1.

[0153] In Table 1, BZ represents benzene.

[0154] In Table 1, compared with Comparative Example 1, Examples 1 and 5-10 used specific ether solvents in Examples 1 and 5-10. In contrast, the Comparative Example used conventional dimethyl ethylene glycol (DME). Electrolytes containing the ether solvents of this application can reduce gas production in lithium metal battery cells and achieve better cycle life. The reason for this is that the CO bond in dimethyl ethylene glycol breaks, yielding a CH3· radical. This radical is unstable and reacts with DME to produce a hydrogen atom to form methane (CH4). The specific ether solvents of this application produce less gas, thus improving the cycle life of lithium metal battery cells.

[0155] Compared with Example 1, Examples 2-4 have different molar ratios of lithium salt and ether solvent, which have a certain impact on the gas generation and cycle life of lithium metal battery cells.

[0156] Compared to Example 1, Examples 11-13 added a diluent, adjusted the viscosity and conductivity of the electrolyte, further reduced the amount of gas generated by the lithium metal battery cells, and improved the cycle life of the lithium metal battery cells.

[0157] Compared to Comparative Example 2, Example 13 used a specific ether solvent. Compared to the comparative example which used conventional dimethyl ethylene glycol (DME), the electrolyte in Example 13 containing a specific ether solvent can reduce gas production in lithium metal battery cells and has a better cycle life.

[0158] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A lithium metal battery cell, wherein, The electrolyte includes an electrode assembly and an electrolyte solution; the electrode assembly includes a lithium metal negative electrode; the electrolyte solution includes a lithium salt and an ether solvent, wherein the ether solvent includes one or more of the structures shown in formula (1) and formula (2): R1 and R6 independently include any one of C1-C7 alkyl or C1-C7 alkenyl groups, whether unsubstituted or substituted with halogen atoms; R2, R4, and R5 include any one of C1-C4 alkylene groups, whether unsubstituted or substituted with halogen atoms; R3 includes any one of C3-C7 alkyl groups, whether unsubstituted or substituted with halogen atoms; R1 and R3 are not simultaneously unsubstituted or substituted with halogen atoms of either C3-C7 alkyl or C3-C7 alkenyl groups.

2. The lithium metal battery cell according to claim 1, wherein, The ether solvent satisfies one or more of the following conditions: 1) R1 includes any one of C1-C2 alkyl or C1-C2 alkenyl groups; R2 includes any one of C1-C4 alkylene groups; R3 includes unsubstituted or halogen-substituted C3-C7 alkyl or C3-C7 alkenyl groups. 2) R6 includes any one of C1 to C7 alkyl groups and C1 to C7 alkenyl groups, R4 includes any one of C1 to C4 alkylene groups, and R5 includes any one of C1 to C4 alkylene groups that are unsubstituted or substituted with halogen atoms.

3. The lithium metal battery cell according to claim 1 or 2, wherein, R6 includes the structure shown in any one of equations (I-1) to (I-10); and / or, R1 includes the structure shown in any one of equations (I-1) or (I-3), and R3 includes the structure shown in any one of equations (I-4) to (I-10): in, For the connection point, R7 includes any one of the following: a connecting bond, or a C1 to C4 alkylene group.

4. The lithium metal battery cell according to any one of claims 1 to 3, wherein, The ether solvent comprises the structure shown in formula (1), and the ether solvent comprises the structure shown in any one of formulas (J-1) to (J-9):

5. The lithium metal battery cell according to any one of claims 1 to 4, wherein, The ether solvent comprises the structure shown in formula (2), and the ether solvent comprises the structure shown in any one of formulas (H-1) to (H-8):

6. The lithium metal battery cell according to any one of claims 1 to 5, wherein, The ether solvent comprises the structure shown in formula (2), and the ether solvent comprises the structure shown in any one of formulas (K-1) to (K-17):

7. The lithium metal battery cell according to any one of claims 1 to 6, wherein, The lithium salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

8. The lithium metal battery cell according to any one of claims 1 to 7, wherein, The molar ratio of the lithium salt to the ether solvent is 1:(1-4).

9. The lithium metal battery cell according to any one of claims 1 to 8, wherein, The electrolyte further includes a diluent comprising one or more of the following: 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl, 1-(1,1,2,2-tetrafluoroethoxy)propane, 1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, benzene, and anisole.

10. The lithium metal battery cell according to claim 9, wherein, The molar ratio of the lithium salt, the ether solvent, and the diluent is 1:(1-4):(0.5-2).

11. The lithium metal battery cell according to any one of claims 1 to 10, wherein, The electrolyte meets one or more of the following conditions: 1) The conductivity of the electrolyte is from 0.5 mS / cm to 10 mS / cm; 2) The viscosity of the electrolyte is from 2 mPa·s to 20 mPa·s.

12. The lithium metal battery cell according to any one of claims 1 to 11, wherein, The electrode assembly also includes a separator and a positive electrode stacked with the lithium metal negative electrode.

13. An electrolyte for use in lithium metal battery cells, wherein, The electrolyte comprises lithium salt and ether solvent, wherein the ether solvent comprises one or more of the structures shown in formula (1) and formula (2): R1 and R6 independently include any one of C1-C7 alkyl or C1-C7 alkenyl groups, whether unsubstituted or substituted with halogen atoms; R2, R4, and R5 include any one of C1-C4 alkylene groups, whether unsubstituted or substituted with halogen atoms; R3 includes any one of C3-C7 alkyl groups, whether unsubstituted or substituted with halogen atoms; R1 and R3 are not simultaneously unsubstituted or substituted with halogen atoms of either C3-C7 alkyl or C3-C7 alkenyl groups.

14. A battery device, wherein, Includes the lithium metal battery cell according to any one of claims 1 to 12 or the battery cell made from the electrolyte according to claim 13.

15. An electrical appliance, wherein, Includes the battery device as described in claim 14.

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