Battery cell, electrolyte, battery device, and electric device

Abstract

The invention provides a battery cell, an electrolyte, a battery device and an electric device. The battery monomer comprises an electrolyte, the electrolyte comprises an electrolyte salt, an organic solvent and a thioester additive, and the mass content of the thioester additive in the electrolyte is 0.001-10%; the thioester additive comprises a structure as shown in any one or more of a formula (1) to a formula (6), R1 and R2 respectively and independently comprise hydrogen atoms and unsubstituted or heteroatom substituted alkyl with the carbon atom number of 1-10, n and m are respectively integers, n is 1-4, and m is 0-4. The dynamic performance of the battery monomer is better; the electrolyte can participate in the formation of a solid electrolyte membrane, so that the dynamic performance of a battery monomer is improved; the battery device and the power utilization device comprising the battery monomer at least have the above beneficial effects.

Description

Technical Field

[0001] This application belongs to the field of battery cell technology, specifically relating to a battery cell, electrolyte, battery device, and power-consuming device. Background Technology

[0002] In recent years, battery cells have been widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and many other fields. With the application and promotion of battery cells, their comprehensive performance has received increasing attention; for example, battery cells need to simultaneously meet requirements such as high reliability and strong charging performance. The electrolyte in a battery cell plays a crucial role in transferring active ions and is one of the key factors affecting the performance of the battery cell.

[0003] Therefore, there is an urgent need to provide a battery cell with good overall performance. Summary of the Invention

[0004] This application provides a battery cell with superior kinetic performance; the electrolyte of this application can participate in the formation of a solid electrolyte membrane, thereby improving the kinetic performance of the battery cell; the battery device and the power supply device containing the battery cell have at least the above-mentioned beneficial effects.

[0005] In a first aspect, embodiments of this application provide a battery cell including an electrolyte; the electrolyte includes an electrolyte salt, an organic solvent, and a thioester additive, wherein the thioester additive includes the structure shown in any one or more of formulas (1) to (6):

[0006] R1 and R2 each independently include hydrogen atoms and alkyl groups with 1 to 10 unsubstituted or heteroatomic carbon atoms; n and m are integers, with n being 1 to 4 and m being 0 to 4.

[0007] In this embodiment, the thioester additive is dispersed in an electrolyte containing an electrolyte salt and an organic solvent. The thioester additive can participate in the formation of the solid electrolyte interphase (SEI) membrane, meaning it is reduced to a sulfur-containing electrolyte salt component and introduced into the SEI, thus improving the kinetic performance of the battery cell. The reason for this is that the binding energy ΔE between sulfur and active ions (e.g., S-Li) is lower than the binding energy between active ions and oxygen, reducing the binding energy between elements and active ions in the SEI and lowering the transport barrier of active ions in the SEI membrane. This allows active ions to transport more easily in the SEI, reducing the charging impedance Rct.

[0008] In some optional embodiments, the thioester additive has a mass content of 0.001% to 10% in the electrolyte, optionally 0.5% to 2%. A mass content of the thioester additive in the electrolyte within the above range is beneficial for further reducing the transport energy barrier of active ions in the SEI membrane and improving the kinetic performance of the battery cell.

[0009] In some optional embodiments, R1 and R2 independently comprise hydrogen atoms and alkyl groups having 1 to 4 carbon atoms, respectively. The use of these types of groups in R1 and R2, compared to other groups substituted with heteroatoms, reduces side reactions such as corrosion of the battery cells, lowers the probability of thioester additives releasing toxic gases under extreme conditions such as overheating or overcharging, and improves the reliability and cycle life of the battery cells.

[0010] In addition, R1 and R2 use the aforementioned types of groups, which are more easily degraded in the natural environment and cause less damage to the environment.

[0011] In some optional embodiments, the thioester additive comprises the structure shown in any one or more of formulas (I-1) to (I-26):

[0012]

[0013] In the embodiments of this application, the aforementioned thioester additives can participate in the formation of the SEI film and improve the kinetic performance of the battery cell. The reason for this is that it lowers the transport energy barrier of active ions in the SEI film, making it easier for active ions to transport within the SEI.

[0014] In some optional embodiments, the concentration of the electrolyte salt in the electrolyte is from 0.5 mol / L to 3 mol / L, optionally from 0.8 mol / L to 1.2 mol / L. Maintaining the electrolyte salt concentration within this range can optimize the interfacial characteristics between the electrode and the electrolyte, enhance the interfacial stability of the battery, and improve the lifespan of the battery cells.

[0015] In some optional embodiments, the organic solvent comprises 60% to 95% by mass in the electrolyte, optionally 80% to 88%. Therefore, the viscosity and ionic conductivity of the electrolyte can be further controlled, thereby improving the kinetic performance of the battery cell.

[0016] In some optional embodiments, the mass ratio of thioester additive to organic solvent is 1:(5-1000), optionally 1:(7.8-881). Within the above range, the organic solvent and thioester additive are beneficial for further reducing the transport energy barrier of active ions in the SEI film, thereby improving the kinetic performance of the battery cell.

[0017] In some optional embodiments, the electrolyte salt includes a lithium salt, one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium (trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobis(oxalate)phosphate, lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium tetrafluorooxalate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluorooxalate.

[0018] In some optional embodiments, the organic solvent includes one or more of carbonates. Therefore, the aforementioned organic solvents facilitate the dissociation of the electrolyte from the electrolyte salt, thereby improving the performance of the battery cell.

[0019] In some alternative embodiments, the battery includes a negative electrode sheet, which includes a negative electrode active material, including one or more of silicon-carbon, silicon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, hard carbon, lithium metal, sodium metal, and lithium alloys. The combination of these negative electrode materials with an electrolyte can improve the performance of the battery cell.

[0020] In some optional embodiments, the electrolyte is a liquid electrolyte with a conductivity of 10 to 40 mS / cm. -1 12 to 20 mS cm can be selected. -1 The aforementioned conductivity can reduce the internal resistance of individual battery cells, increase the charge transfer rate, improve kinetic performance, and enable individual battery cells to maintain high energy output at high current densities. This conductivity also helps reduce uneven current distribution and improve the cycle life of individual battery cells.

[0021] In some optional embodiments, the electrolyte is a liquid electrolyte with a viscosity of 1 to 20 mPa s, optionally 1.5 to 3 mPa s. An electrolyte viscosity within this range helps to increase the diffusion coefficient of active ions, thereby accelerating charge transfer and improving the kinetic performance of the battery cell. An electrolyte with the aforementioned viscosity also helps to balance the lithium deposition process, reduce dendrite formation, and improve the stability and cycle life of the battery cell.

[0022] In some optional embodiments, the battery cell includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium iron manganese phosphate, sodium iron phosphate, and sodium iron pyrophosphate.

[0023] Secondly, embodiments of this application provide an electrolyte for a battery cell, the electrolyte comprising an electrolyte salt, an organic solvent, and a thioester additive, wherein the thioester additive comprises the structure shown in any one or more of formulas (1) to (6):

[0024] Wherein, R1 and R2 independently include hydrogen atoms and alkyl groups with 1 to 10 unsubstituted or heteroatomic carbon atoms, and n and m are integers, where n is 1 to 4 and m is 0 to 4.

[0025] In the embodiments of this application, the thioester additive in the electrolyte can participate in the formation of the solid electrolyte membrane (SEI membrane), that is, the thioester additive is reduced to sulfur-containing electrolyte salt components and introduced into the SEI, thereby improving the kinetic performance of the battery cell.

[0026] Thirdly, embodiments of this application provide a battery device comprising a battery cell of the first aspect or a battery cell prepared using an electrolyte of the second aspect. The battery device of this application comprises a battery cell of the first aspect or a battery cell prepared using an electrolyte of the second aspect, and therefore has at least the advantages of either a battery cell or an electrolyte.

[0027] 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

[0028] 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.

[0029] Figure 1 A schematic diagram of one embodiment of the battery cell of this application is shown.

[0030] Figure 2 It shows Figure 1 An exploded view of one embodiment of the battery cell is shown.

[0031] Figure 3 A schematic diagram of the battery pack according to one embodiment of this application is shown.

[0032] Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0033] Figure 5 A schematic diagram of one embodiment of an electrical device incorporating the battery cell of this application as a power source is shown.

[0034] The reference numerals in the attached diagram are explained as follows: 1. Battery pack, 2. Upper housing, 3. Lower housing, 4. Battery module, 5. Individual battery cell.

[0035] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0036] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the 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.

[0037] 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 the 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 specific parameters, 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, characterized in that a and b are both 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.

[0038] 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.

[0039] 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.

[0040] Throughout this application, substituents of the 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-C10 alkyl" individually discloses C1, C2, C3, C4, C5, C6, C7, C9, C10, C1-C2, C1-C3, C1-C4, C1-C5, C1-C6, C1-C7, C1-C8, C1-C9, C1-C10, C2-C3, C2-C4, C2-C5, C2-C6, C2-C7, C2-C8, C2-C9, C2-C10, C3-C4, C3-C 5. C3–C6, C3–C7, C3–C8, C3–C9, C3–C10, C4–C5, C4–C6, C4–C7, C4–C8, C4–C9, C4–C10, C5–C6, C5–C7, C5–C8, C5–C9, C5–C10, C6–C7, C6–C8, C6–C9, C6–C10, C7–C8, C7–C9, C7–C10, C8–C9, C8–C10, and C9–C10 alkyl groups. Unless otherwise stated, the term "alkyl" encompasses both straight-chain alkyl and branched-chain alkyl groups.

[0041] 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 battery cell, including but not limited to lithium ions, sodium ions, etc.

[0042] In this application, "multiple" refers to two or more (including two). Similarly, "several items" or "multiple items" in this application refers to two or more (including two).

[0043] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0044] In some alternative embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells into a single module. As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0045] A single battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A single battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

[0046] In some alternative embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 2 This is a schematic diagram of battery module 4 as an example. Figure 2 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0047] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0048] 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.

[0049] Figure 3 and Figure 4 This is a schematic diagram of battery pack 1 as an example. Figure 3 and Figure 4 As shown, 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. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0050] In some alternative embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0051] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0052] The battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-metal hydride battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., but the embodiments of this application are not limited to this.

[0053] The battery cell may also include an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0054] A battery includes an electrode assembly and an electrolyte. The electrode assembly typically includes a positive electrode, a negative electrode, and a separator. The electrode assembly can be a wound structure or a stacked structure; this application does not limit this.

[0055] [Electrolytes]

[0056] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel-like, or solid.

[0057] In some embodiments, the electrolyte comprises an electrolyte salt, an organic solvent, and a thioester additive, wherein the thioester additive comprises a structure shown in any one or more of formulas (1) to (6):

[0058]

[0059] R1 and R2 each independently include hydrogen atoms and alkyl groups with 1 to 10 unsubstituted or heteroatomic carbon atoms; n and m are integers, with n being 1 to 4 and m being 0 to 4.

[0060] The heteroatom can be one or more of the following: halogen atom, sulfur atom, nitrogen atom, phosphorus atom, oxygen atom, and boron atom. When M is 0, the expression (6) is a 5-membered ring, and the carbon atom in the parentheses is either absent or empty.

[0061] In the embodiments of this application, the thioester additive is dispersed in the electrolyte formed by the electrolyte salt and organic solvent. The thioester additive can participate in the formation of the solid electrolyte membrane (SEI membrane). That is, the thioester additive is reduced to a sulfur-containing electrolyte salt component and introduced into the SEI. The binding energy ΔE of sulfur element with active ions (e.g., S-Li) is lower than the binding energy of active ions with oxygen element, which reduces the binding energy of elements with active ions in the SEI and also reduces the transport energy barrier of active ions in the SEI membrane, making it easier for active ions to transport in the SEI, reducing the charging impedance Rct, and thus improving the dynamic performance of the battery cell.

[0062] In related technologies, the high diffusion barrier of Li+ in the SEI film is detrimental to the transport of active ions within the SEI. SEI films generally contain oxygen, and the binding element for Li+ changes from oxygen to sulfur, lowering the binding energy between the SEI film and Li+. The reason for this is that oxygen has a higher electronegativity (3.44) than sulfur (2.58). Higher electronegativity means a stronger attraction between atoms and electrons. This electronegativity difference affects the electron cloud distribution and ionic bond strength between Li+ and anions, resulting in a higher binding energy between Li+ and O than between Li+ and S. Sulfur atoms have a larger radius than oxygen atoms, and due to the more dispersed electron cloud of sulfur, the polarization of Li+ on S2- is lower, leading to a weaker ionic bond and thus a lower binding energy. This reduces the transport barrier of active ions in the SEI film, improving the kinetic performance of the battery cell.

[0063] Thioester additives are added during the preparation of the electrolyte for battery cells. After the battery cells undergo electrochemical cycling, the content of thioester additives may be low, extremely small, or even absent. The presence of thioester additives can be detected through their products in the solid electrolyte membrane and the performance of the battery cells.

[0064] Electrolytes, including thioester additives, can also be understood as components or raw materials of electrolytes.

[0065] In some alternative embodiments, the liquid electrolyte, i.e., the electrolyte solution, includes an electrolyte salt, a thioester additive, and an organic solvent.

[0066] In some optional embodiments, the thioester additive has a mass content of 0.001% to 10% in the electrolyte, optionally 0.5% to 2%.

[0067] Optionally, the mass content of the thioester additive in the electrolyte can be 0.001%, 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, or 1%.

[0068] Any value or range of composition from 7.5%, 8%, 8.5%, 9%, 9.5%, and 10% in the electrolyte. A mass content of thioester additives within the above range is beneficial for further reducing the transport energy barrier of active ions in the SEI film and improving the kinetic performance of the battery cell.

[0069] In some optional embodiments, R1 and R2 independently comprise hydrogen atoms, alkyl groups having 1 to 4 carbon atoms substituted or unsubstituted with non-halogen atoms. This improves the reliability and cycle life of the battery cell.

[0070] In some optional embodiments, R1 and R2 independently comprise hydrogen atoms and alkyl groups having 1 to 4 carbon atoms, respectively.

[0071] R1 and R2 use the aforementioned groups, which, compared to other groups substituted with heteroatoms, reduce side reactions such as corrosion to battery cells, reduce the probability of thioester additives releasing toxic gases under extreme conditions such as overheating or overcharging, and improve the reliability and cycle life of battery cells.

[0072] In addition, R1 and R2 use the aforementioned types of groups, which are more easily degraded in the natural environment and cause less damage to the environment.

[0073] In some optional embodiments, the thioester additive comprises the structure shown in any one or more of formulas (I-1) to (I-26):

[0074]

[0075] In the embodiments of this application, the above-mentioned thioester additives can participate in the formation of the SEI film, reduce the transport energy barrier of active ions in the SEI film, make it easier for active ions to be transported in the SEI, and improve the kinetic performance of the battery cell.

[0076] For example, a solid electrolyte membrane exists at the interface between the negative electrode and the electrolyte. The solid electrolyte membrane includes sulfur-containing products that participate in the formation of the SEI membrane with thioester additives, which further improves the kinetic performance of the battery cell.

[0077] In some optional embodiments, the concentration of the electrolyte salt in the electrolyte is from 0.5 mol / L to 3 mol / L, and optionally from 0.8 mol / L to 1.2 mol / L.

[0078] The concentration of the electrolyte salt in the electrolyte can be any value or range of the following: 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L.

[0079] When the electrolyte salt content is within the above range, the interfacial characteristics between the electrode and the electrolyte can be optimized, the interfacial stability of the battery can be enhanced, and the service life of the battery cell can be increased.

[0080] In some optional embodiments, the organic solvent comprises 60% to 95% by mass in the electrolyte, optionally 80% to 88%.

[0081] Optionally, the mass content of the organic solvent in the electrolyte can be any value or a range thereof from 60%, 65%, 70%, 75%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, and 95%. Therefore, the viscosity and ionic conductivity of the electrolyte can be further controlled, thereby improving the kinetic performance of the battery cell.

[0082] In some optional embodiments, the mass ratio of thioester additive to organic solvent is 1:(5-1000), optionally 1:(7.8-881).

[0083] Optionally, the mass ratio of the organic solvent to the thioester additive can be any value or a range thereof from 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90, 1:95, 1:100, 1:200, 1:300, 1:400, 1:500, 1:600, 1:700, 1:800, 1:900, and 1:1000. A mass content of the thioester additive in the electrolyte within the above range is beneficial for further reducing the transport energy barrier of active ions in the SEI membrane and improving the kinetic performance of the battery cell.

[0084] In some optional embodiments, the battery cell includes a solid electrolyte membrane (SEI) and a negative electrode. The SEE is located at the interface between the negative electrode and the electrolyte. The SEE includes a lithium-containing product formed by the participation of a thioester additive. The binding energy ΔE (e.g., S-Li) between sulfur and active ions is lower than that between active ions and oxygen, which reduces the binding energy between elements and active ions in the SEI and lowers the transport barrier of active ions in the SEI. This makes it easier for active ions to transport in the SEI, reduces the charging impedance Rct, and further improves the kinetic performance of the battery cell.

[0085] In some alternative embodiments, the electrolyte salt includes one or more of lithium salts, lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium (trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobis(oxalate)phosphate, lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium tetrafluorooxalate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluorooxalate.

[0086] In some optional embodiments, the electrolyte salt may be a sodium salt, including but not limited to one or more of NaPF6, NaClO4, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3.

[0087] In some alternative embodiments, the electrolyte comprises anion, which may include bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), dioxaborate anion (BOB) - ), difluorooxalate borate anion (DFOB) - ), difluorodioxanol phosphate anion (DFOP) - ), tetrafluorooxalate phosphate anion (TFOP) - ), difluorophosphate anion (PO2F2) - ), hexafluorophosphate anion (PF6) - ), tetrafluoroborate anion (BF4) - ), hexafluoroarsenate anion (AsF6) - ), trifluoromethanesulfonate anion (CF3SO3) - One or more of the following.

[0088] In some alternative embodiments, the electrolyte includes a cation, which may include lithium ions, sodium ions, etc.

[0089] In some optional embodiments, to balance the electrolyte cost and kinetic performance of the battery cell, the high-temperature storage performance of the battery cell is also improved. The organic solvent may include carbonates, carboxylic esters, and ether solvents. Optionally, the carbonate may include both cyclic carbonates and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0090] As an example, organic solvents may include, but are not limited to, ethylene carbonate (EC), propylene carbonate (PC), butene carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE), dimethyl ether tetraethylene glycol (TEGDME), ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL), trimethyl phosphate, 3-methoxypropionitrile, H(CF2)2OCH3, C4F9O CH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, CF3CHFCF2OCH3, CF3CHFCF2OCH2CH3, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyl The ester may be one or more of the following: 4-trifluoromethyldecafluoropentyl methyl ether, 4-trifluoromethyldecafluoropentyl ethyl ether, 4-trifluoromethyldecafluoropentyl propyl ether, 5-trifluoromethyldodecylfluorohexyl methyl ether, 5-trifluoromethyldodecylfluorohexyl ethyl ether, 5-trifluoromethyldodecylfluorohexyl propyl ether, 6-trifluoromethyltetradecylfluoroheptyl methyl ether, 6-trifluoromethyltetradecylfluoroheptyl ethyl ether, 6-trifluoromethyltetradecylfluoroheptyl propyl ether, 7-trifluoromethylhexadecylfluorooctyl methyl ether, 7-trifluoromethylhexadecylfluorooctyl ethyl ether, and 7-trifluoromethylhexadecylfluorooctyl propyl ether. As an example, the carboxylic acid ester may be methyl acetate. As an example, the ether solvent may be ethylene glycol dimethyl ether.

[0091] In some alternative embodiments, the electrolyte includes an electrolyte salt, a thioester additive, and an organic solvent. The organic solvent may include carbonates. When the organic solvent is a carbonate solvent, it can further improve the kinetic and cycle performance of the battery cell compared to ether solvents or carboxylic esters.

[0092] In some alternative embodiments, the conductivity of the electrolyte is 10 to 40 mS / cm. -1 12 to 20 mS cm can be selected. -1 .

[0093] Optionally, the conductivity of the electrolyte can be any value or a range thereof from 10.0 mS / cm, 10.5 mS / cm, 11.5 mS / cm, 12.0 mS / cm, 12.5 mS / cm, 13.0 mS / cm, 13.5 mS / cm, 14.0 mS / cm, 14.5 mS / cm, 15.0 mS / cm, 15.5 mS / cm, 16.0 mS / cm, 16.5 mS / cm, 17.0 mS / cm, 17.5 mS / cm, 18.0 mS / cm, 18.5 mS / cm, 19.0 mS / cm, 19.5 mS / cm, 20.0 mS / cm, 25.0 mS / cm, 30.0 mS / cm, 35.0 mS / cm, and 40.0 mS / cm. The conductivity of the electrolyte reflects the migration ability of active ions in the electrolyte. The aforementioned conductivity can reduce the internal resistance of individual battery cells, increase the charge transfer rate, improve kinetic performance, and enable individual battery cells to maintain high energy output under high current density. This conductivity also helps reduce uneven current distribution and improve the cycle life of individual battery cells.

[0094] The conductivity of an 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.

[0095] In some optional embodiments, the viscosity of the electrolyte is 1 to 20 mPa s, optionally 1.5 to 3 mPa s.

[0096] Optionally, the viscosity of the electrolyte can be any value or a range thereof from 1.0 mPa·s, 1.1 mPa·s, 1.2 mPa·s, 1.3 mPa·s, 1.4 mPa·s, 1.5 mPa·s, 1.6 mPa·s, 1.7 mPa·s, 1.8 mPa·s, 1.9 mPa·s, 2.0 mPa·s, 2.1 mPa·s, 2.5 mPa·s, 3.0 mPa·s, 3.5 mPa·s, 4.0 mPa·s, 5.0 mPa·s, 10.0 mPa·s, 15.0 mPa·s, and 20.0 mPa·s. The viscosity of the electrolyte affects the diffusion rate of active ions within the electrolyte. A viscosity within the above range helps to increase the diffusion coefficient of active ions, thereby accelerating charge transfer and improving the kinetic performance of the battery cell. The electrolyte with the above viscosity helps to balance the lithium deposition process, reduce dendrite formation, and improve the stability and cycle life of the battery cells.

[0097] The viscosity of an electrolyte can be tested using a viscometer. When a rotor rotates continuously at a constant speed within a sample, the shear force it experiences causes a torque to be generated in the spring. This torque is proportional to the viscosity, thus yielding the viscosity value of the sample.

[0098] As an example, the viscosity of an electrolyte can be tested as follows: Under ambient humidity <80%, take a 30 mL sample and keep it at a constant temperature of 25°C in a water bath for at least 30 minutes. Place a rotor (e.g., a No. 18 rotor) into the sample cup, add the sample to approximately 0.3 cm from the rim, start the connected viscometer, select a speed of 70 RPM, 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.

[0099] In some alternative embodiments, the electrolyte may also optionally include other additives. For example, other additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0100] In some alternative embodiments, the gel electrolyte comprises a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0101] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0102] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0103] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium-germanium-phosphorus-sulfur, sulfosilium-germanium), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0104] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0105] The preparation methods for electrolytes are well known. For example, an electrolyte salt, an organic 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.

[0106] 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.

[0107] For example, infrared spectroscopy can be used to identify compounds in electrolytes, such as the characteristic peaks of sulfur-carbon single bonds in thioester additives, which are in the range of 1000-1200 cm⁻¹. 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, nuclear magnetic resonance (NMR) spectroscopy results can confirm the specific molecular structure of each component.

[0108] As an example, the types and contents of inorganic components / electrolyte salts in the electrolyte can be qualitatively or quantitatively analyzed using ion chromatography, referring to standard JY / T020-1996 "General Rules for Ion Chromatography Analysis". In the embodiments of this application, freshly prepared electrolytes can be used as samples, or the free electrolyte from a fresh battery can be used as a sample. Alternatively, a fully discharged battery (discharged to the lower cutoff voltage so that the battery's state of charge is approximately 0% SOC) can be disassembled in reverse, and the free electrolyte obtained from the battery can be used as a sample for detection using ion chromatography.

[0109] As an example, the types and contents of organic components in the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography, referring to GB / T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents". In the embodiments of this application, freshly prepared electrolytes can be used as samples, free electrolytes from fresh batteries can be used as samples, or batteries that have been completely discharged (discharged to the lower limit cutoff voltage so that the battery's state of charge is approximately 0% SOC) can be disassembled in reverse, and the free electrolytes obtained from the batteries can be used as samples for detection by ion chromatography.

[0110] [Positive electrode plate]

[0111] In some alternative embodiments, the positive electrode includes a positive current collector and a positive active material film layer disposed on at least one surface of the positive current collector, the positive active material 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 active material film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0112] The type of positive electrode active material can be selected according to the type of battery cell, and this application embodiment does not limit this.

[0113] 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.

[0114] 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.).

[0115] As an example, the positive electrode active material may include at least one of the following materials: lithium iron phosphate and lithium iron manganese phosphate, 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. Among them, at least one of 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 iron manganese phosphate, and lithium iron manganese phosphate and carbon composites may be used.

[0116] In some optional embodiments, the positive electrode active material includes lithium transition metal oxides. Examples 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 0.3 O2 (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 0.8Co 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.

[0117] In some optional embodiments, the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium iron manganese phosphate, sodium iron phosphate, and sodium iron pyrophosphate.

[0118] When the battery cell is a sodium-ion battery cell, a sodium metal battery cell, etc., the positive electrode active material may include, but is not limited to, one or more of the following: sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials.

[0119] As an example, positive electrode active materials may include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials and materials with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In the given condition, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes elements selected from H. + Li + Na + K + and NH4 +One or more of the following, M' is a transition metal cation, which may be selected from one or more of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, which may be selected from one or more of F, Cl and Br.

[0120] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0121] During the charging and discharging process, battery cells undergo Li or Na insertion / extraction and consumption, resulting in varying molar contents of Li or Na at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar contents of Li or Na represent the initial state of the material, i.e., the state before material addition. After charge-discharge cycles, the molar contents of Li or Na will change when the positive electrode active material is applied to the battery cell. Similarly, the molar contents of oxygen (O) in the examples of positive electrode active materials in this disclosure are only theoretical values. Lattice oxygen release will cause changes in the molar contents of O, and the actual molar contents of O will also fluctuate.

[0122] In some alternative embodiments, the positive electrode sheet can be made of 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, positive electrode active material is filled and / or deposited within the foamed metal.

[0123] In some optional embodiments, the positive electrode active material 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.

[0124] In some optional embodiments, the positive electrode active material 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.

[0125] 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).

[0126] The positive electrode active material film layer 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.

[0127] [Negative electrode plate]

[0128] In some alternative embodiments, the negative electrode may include a negative current collector.

[0129] As an example, the negative electrode 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 substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper 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.).

[0130] In some alternative embodiments, the negative electrode can be a negative electrode sheet, which may include a negative electrode material film layer disposed on at least one side of the negative electrode current collector.

[0131] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0132] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0133] In some alternative embodiments, the negative electrode active material includes one or more of silicon-carbon, silicon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, hard carbon, lithium metal, sodium metal, and lithium alloys.

[0134] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0135] In some alternative embodiments, the negative electrode can be made of 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 negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0136] As an example, negative electrode active materials can be filled or / and deposited within the negative electrode current collector.

[0137] In some alternative embodiments, the negative electrode current collector can be made of copper.

[0138] For example, when the battery cell is a lithium metal battery cell, the 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. The metal element in the first metal layer may include one or more of alkali metal elements and alkaline earth metal elements.

[0139] For example, when the battery cell is a sodium battery cell, in some alternative embodiments, the negative electrode may include a sodium sheet or a sodium alloy sheet.

[0140] In some alternative embodiments, the metal material in the first metal layer may include one or more of elemental lithium and lithium alloys.

[0141] 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.

[0142] [Isolation Component]

[0143] In some optional embodiments, the separator can be a separator membrane. The separator membrane can be disposed between the positive electrode and the negative electrode, mainly to prevent internal short circuits. This application does not have any particular limitation on the type of separator membrane; any known porous membrane with good chemical and mechanical stability can be selected.

[0144] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0145] 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.

[0146] In some alternative embodiments, the separator can be 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.

[0147] The methods for preparing 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 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 package, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained. Multiple battery cells can be further connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some optional embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0148] Electrical appliances

[0149] This application provides an electrical device, including the battery device described above.

[0150] A single battery cell can be used as a power source for an electrical device or as an energy storage unit for that device. 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.

[0151] Electrical devices can be equipped with individual battery cells, battery modules, or battery packs depending on their usage requirements.

[0152] Figure 5 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0153] 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 use a single battery cell as their power source.

[0154] Example

[0155] 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.

[0156] Example 1

[0157] Electrolyte preparation: Ethyl carbonate, diethyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 1:1:1. LiPF6 was dissolved in the mixture at a concentration of 1 mol / L. Based on the final total mass of the electrolyte, 1% by mass of thioester additive, namely ethyl thioester, was added to obtain the electrolyte.

[0158] Preparation of battery cells:

[0159] Preparation of positive electrode sheet: Lithium iron phosphate, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8:1:1, and N-methylpyrrolidone is added to obtain positive electrode slurry. The positive electrode slurry is coated on one side of an aluminum foil with a thickness of 15 micrometers to form a positive electrode active material film. After cold pressing and cutting, the positive electrode sheet is obtained.

[0160] Preparation of negative electrode sheet: Graphite, conductive carbon black, aqueous dispersant sodium carboxymethyl cellulose (CMC), aqueous binder styrene-butadiene latex (SBR) and solvent water are uniformly mixed in a weight ratio of 95:1:1:3:100 to prepare negative electrode slurry. The negative electrode slurry is coated on both sides of a copper foil with a thickness of 5 micrometers to form a negative electrode active material film layer. After cold pressing and cutting, the negative electrode sheet is obtained.

[0161] Preparation of the separator: A polyethylene film with a thickness of 12 μm was used as the separator.

[0162] Assembly: The positive electrode is placed in the order of "positive electrode - separator - negative electrode - separator - positive electrode" to obtain a stacked battery, with the positive active material film layer of the positive electrode facing the separator side.

[0163] Examples 2-4

[0164] The preparation method is similar to that in Example 1, except that the mass content of the thioester additive in the electrolyte is different, as shown in Table 1.

[0165] Examples 5-10

[0166] The preparation method is similar to that of Example 1, except that the type of thioester additive is different. The thioester additive in Example 1 is replaced with an equal mass of other types of thioester additives, as shown in Table 1.

[0167] Examples 11-12

[0168] The preparation method is similar to that of Example 1, except that the type of thioester additive is different. The thioester additive in Example 1 is replaced with an equal mass of other types of thioester additive. The structure of Example 11 is shown in formula (K-1); the structure of Example 12 is shown in formula (K-2).

[0169]

[0170] Examples 13-16

[0171] The preparation method is similar to that of Example 1, except that the type of thioester additive is different. The thioester additive in Example 1 is replaced with an equal mass of other types of thioester additives, as shown in Table 1.

[0172] Examples 17-18

[0173] The preparation method is similar to that in Example 1, except that the organic solvent in the electrolyte is different. The organic solvents are equal volumes of ethylene glycol dimethyl ether and methyl acetate, and the concentration of LiPF6 is still 1 mol / L, as shown in Table 1.

[0174] Example 19

[0175] The preparation method is similar to that in Example 1, except that the composition of the organic solvent in the electrolyte is different, and the dimethyl carbonate in the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether. The concentration of LiPF6 is still 1 mol / L, as shown in Table 1.

[0176] Example 20

[0177] The preparation method is similar to that in Example 19, except that the composition of the organic solvent in the electrolyte is different, and the diethyl carbonate in the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether. The concentration of LiPF6 is still 1 mol / L, as shown in Table 1.

[0178] Comparative Example 1

[0179] The preparation method is similar to that in Example 1, except that the electrolyte is different. No thioester additive is added to the electrolyte, and the concentration of LiPF6 is still 1 mol / L, as shown in Table 1.

[0180] Comparative Example 2

[0181] The preparation method is similar to that in Example 1, except that the mass ratio of organic solvent to thioester additive in the electrolyte is different, and the mass ratio of organic solvent to thioester additive is 1:2. The organic solvent is obtained by mixing organic solvents such as ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The mass content of thioester additive in the electrolyte is 30%, and the concentration of LiPF6 is still 1 mol / L, as shown in Table 1.

[0182] Test section

[0183] 1) Battery cell cycle life test: The ambient temperature for cell cycling is set to 25℃ / 0℃, and a charge / discharge rate of 0.5C (i.e., 70mA) is used for charge / discharge cycles. The cut-off voltages for charge and discharge are set to 3.8V and 2.0V, respectively. The number of cycles completed by the battery cell when the discharge capacity decays to 80% of the first discharge capacity is the cycle life of the battery cell.

[0184] 2) Battery cell charging rate test: At 25℃ or -10℃, with the negative electrode potential of 0mV as the cutoff condition, the maximum charge capacity (SOC) that can be achieved under different charging rates is tested. The charging time under different SOC ranges is obtained by dividing different charging rates. The total charging time T is obtained by summing the charging times. The equivalent charging rate = SOC / T. The charging capability is evaluated by the magnitude of the equivalent charging rate.

[0185] The test results are shown in Table 1.

[0186]

[0187]

[0188] As shown in Table 1, compared with Comparative Examples 1-2, Examples 1 and 5-16, with the addition of the above-mentioned mass of thioester additives, improved the high-temperature charging performance and low-temperature charging performance of the battery cells, and also improved the cycle life of the battery cells.

[0189] Compared with Examples 17-20, Example 1 shows that carbonate organic solvents, compared with ether solvents and carboxylic esters, further improve the high-temperature charging performance and low-temperature charging performance of battery cells, and also further improve the cycle life of battery cells.

[0190] Compared with Examples 11-12, Example 1 shows that the thioester additives that are not substituted with halogen atoms can further improve the high-temperature charging performance and low-temperature charging performance of the battery cells in the electrolyte, and also further improve the cycle life of the battery cells.

[0191] 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 battery cell, characterized in that, The electrolyte comprises an electrolyte salt, an organic solvent, and a thioester additive, wherein the thioester additive is present in the electrolyte at a mass content of 0.001% to 10%; the thioester additive comprises the structure shown in any one or more of formulas (1) to (6): R1 and R2 each independently include hydrogen atoms and alkyl groups with 1 to 10 unsubstituted or heteroatomic carbon atoms; n and m are integers, with n being 1 to 4 and m being 0 to 4.

2. The battery cell according to claim 1, characterized in that, In the structural formulas shown in formula (1) and / or formula (2), R1 and R2 independently include hydrogen atoms and alkyl groups having 1 to 4 carbon atoms, respectively.

3. The battery cell according to claim 1 or 2, characterized in that, The thioester additive comprises the structure shown in any one or more of formulas (I-1) to (I-26). 。 4. The battery cell according to any one of claims 1 to 3, characterized in that, The thioester additive is present in the electrolyte at a mass content of 0.5% to 2%.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The electrolyte satisfies one or more of the following conditions: 1) The concentration of the electrolyte salt in the electrolyte is from 0.5 mol / L to 3 mol / L; 2) The organic solvent comprises 60% to 95% by mass of the electrolyte; 3) The mass ratio of the thioester additive to the organic solvent is 1:(5-1000).

6. The battery cell according to any one of claims 1 to 4, characterized in that, The electrolyte satisfies one or more of the following conditions: 1) The concentration of the electrolyte salt in the electrolyte is from 0.8 mol / L to 1.2 mol / L; 2) The organic solvent comprises 80% to 88% by mass of the electrolyte; 3) The mass ratio of the thioester additive to the organic solvent is 1:(7.8-881).

7. The battery cell according to any one of claims 1 to 6, characterized in that, The electrolyte satisfies one or more of the following conditions: 1) The electrolyte salt includes lithium salts, specifically one or more of lithium difluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium (trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobis(oxalate)phosphate, lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium tetrafluorooxalate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluorooxalate. 2) The organic solvent includes one or more of carbonates, carboxylic esters, and ethers.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The electrolyte is an electrolyte solution, and the electrolyte solution satisfies one or more of the following conditions: 1) The conductivity of the electrolyte is 10 to 40 mS / cm. -1 ; 2) The viscosity of the electrolyte is 1 to 20 mPa·s.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The electrolyte is an electrolyte solution, and the electrolyte solution satisfies one or more of the following conditions: 1) The conductivity of the electrolyte is 12 to 20 mS / cm. -1 ; 2) The viscosity of the electrolyte is 1.5 to 3 mPa·s.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The battery includes a negative electrode sheet, which includes a negative electrode active material, which includes one or more of silicon-carbon, silicon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, hard carbon, lithium metal, sodium metal, and lithium alloy.

11. The battery cell according to any one of claims 1 to 10, characterized in that, The battery cell includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium iron manganese phosphate, sodium iron phosphate, and sodium iron pyrophosphate.

12. An electrolyte for a battery cell, characterized in that, The electrolyte comprises an electrolyte salt, an organic solvent, and a thioester additive, wherein the thioester additive comprises any one or more of the structures shown in formulas (1) to (6): R1 and R2 each independently include hydrogen atoms and alkyl groups with 1 to 10 unsubstituted or heteroatomic carbon atoms; n and m are integers, with n being 1 to 4 and m being 0 to 4.

13. A battery device, characterized in that, This includes the battery cell described in any one of claims 1 to 11 or the battery cell made using the electrolyte described in claim 12.

14. An electrical appliance, characterized in that, Includes the battery device as described in claim 13.

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