Battery cell, battery device and electric device

Abstract

The present application provides a battery cell, a battery device, and an electric device. The battery cell comprises an electrolyte, which comprises an electrolyte salt, an organic solvent, and a sulfur-containing additive. The sulfur-containing additive has a mass content of 0.001% to 10% in the electrolyte and includes structures as shown in any one or more of formulas (a) to (b). In the formulas, X, Y, W, and Z are each independently selected from any one of methylene, O, and S; at least one of X, Y, W, and Z is a sulfur atom, and R1, R2, R3, and R4 each independently comprise a hydrogen atom, an alkyl group with 1 to 10 carbon atoms which is unsubstituted or substituted with a heteroatom, and an alkenyl group with 1 to 10 carbon atoms which is unsubstituted or substituted with a heteroatom; in formula (a), R1 and R4 are connected to form a ring or not connected to form a ring, and R2 and R3 are connected to form a ring or not connected to form a ring; and in formula (b), R1 and R2 are connected to form a ring or not connected to form a ring.

Description

Battery cells, battery packs and electrical devices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 202411570055.6, filed on November 5, 2024, entitled “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 battery cell technology, specifically relating to a battery cell, a battery device, and an electrical device. Background Technology

[0004] 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.

[0005] Therefore, there is an urgent need to provide a battery cell with good overall performance. Summary of the Invention

[0006] This application provides a battery cell that improves the dynamic performance of the battery cell while taking into account the cycle life of the battery cell; the battery device and the power device containing the battery cell have at least the above-mentioned beneficial effects.

[0007] 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 sulfur-containing additive, wherein the mass content of the sulfur-containing additive in the electrolyte is 0.001% to 10%, optionally 0.1% to 1%, and the sulfur-containing additive includes the structure shown in any one or more of formulas (a) to (b):

[0008] X, Y, W, and Z are each independently selected from any one of methylene, O, and S; and at least one of X, Y, W, and Z is a sulfur atom; R1, R2, R3, and R4 each independently include a hydrogen atom, an alkyl group with 1 to 10 unsubstituted or heteroatom-substituted carbon atoms, and an alkenyl group with 1 to 10 unsubstituted or heteroatom-substituted carbon atoms; wherein, in formula (a), R1 and R4 are connected to form a ring or not connected to form a ring, and R2 and R3 are connected to form a ring or not connected to form a ring; in formula (b), R1 and R2 are connected to form a ring or not connected to form a ring.

[0009] In the embodiments of this application, sulfur-containing additives are dispersed in an electrolyte containing electrolyte salts and organic solvents. These additives can participate in the formation of the solid electrolyte interphase (SEI) membrane, improving the kinetic performance of the battery cell, such as rate capability and charging performance, while maintaining the cycle life of the individual cell. Studies have found that the relatively small mass content of sulfur-containing additives in the electrolyte is beneficial for maintaining the viscosity and ionic conductivity of the electrolyte containing organic solvents. Furthermore, the binding energy ΔE (e.g., S-Li) between sulfur and active ions in the sulfur-containing additive is relatively low compared to other elements, such as oxygen, reducing the binding energy between sulfur 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 overall charging impedance Rct of the battery cell and improving both room temperature and low temperature charging performance.

[0010] In some embodiments, the sulfur-containing additive in the electrolyte has a mass content of 0.1% to 10%. When preparing the electrolyte or disassembling an unformed battery cell, the sulfur-containing additive in the electrolyte is within the above range and can be found in the disassembled, formed battery cell. The sulfur-containing additive in the electrolyte is 0.001% to 10%, optionally 0.001% to 6.8%.

[0011] In some embodiments, the sulfur-containing additive in the electrolyte has a mass content of 0.001% to 6.8%, optionally 0.032% to 6.8%. When the formed battery cell is disassembled, the mass content of the sulfur-containing additive in the electrolyte is within the above range, which allows the battery cell to balance the cycle life and charging performance of the battery cell.

[0012] In some embodiments, in formula (a), R1 and R4 are not connected to form a ring, and R2 and R3 are not connected to form a ring. This indicates that the molecular chains in the sulfur-containing additive have a high degree of freedom and are easily spread uniformly on the electrode surface. This is beneficial for maintaining interfacial contact stability and improving the charging performance and cycle life of the battery cells.

[0013] In some embodiments, the sulfur-containing additive comprises the structure shown in any one or more of formulas (1-1) to (1-15):

[0014] Therefore, the application of the aforementioned sulfur-containing additives to the electrolyte can improve the rate performance of individual battery cells.

[0015] In some embodiments, in formula (a), R1 and R4 are connected to form a ring and / or R2 and R3 are connected to form a ring.

[0016] Therefore, the sulfur-containing additive connected into rings has good stability and is suitable for high-voltage positive electrode sheets, such as NCM811 systems, thereby improving the cycle life of battery cells.

[0017] In some embodiments, equation (a) includes the structure shown in any one or more of equations (c) to (f):

[0018] Wherein, n, p, and q are each independent positive integers, and n, p, and q are each independent numbers from 1 to 4. Therefore, the connection of R1 and R4 into a ring and / or R2 and R3 into a ring in the sulfur-containing additive is beneficial for improving the cycle life of the battery cell while considering kinetics.

[0019] In some embodiments, in formula (c), the sulfur-containing additive comprises the structure shown in any one or more of formulas (3-1) to (3-25):

[0020] The above compounds contain a high amount of oxygen in the sulfur-containing additive, which can weaken the binding of Li with the solvent and promote the Li-Li bond. + Desolvation improves kinetic performance.

[0021] In some embodiments, in formula (d), the sulfur-containing additive comprises the structure shown in any one or more of formulas (4-1) to (4-22):

[0022] In some embodiments, in formula (e), the sulfur-containing additive comprises the structure shown in any one or more of formulas (5-1) to (5-25):

[0023] In some embodiments, in formula (f), the sulfur-containing additive comprises the structure shown in any one or more of formulas (6-1) to (6-25):

[0024] In some embodiments, in formula (b), R1 and R2 are not linked to form a ring, and Z represents sulfur. The compound shown in formula (b) can be understood as a compound containing C=S bonds, or as a thioketone or thioaldehyde organic compound. Compounds containing C=S bonds include alkyl and alkenyl groups, which can form rings. Therefore, the reduction of the C=S bonds generates Li2S or organic polysulfides (such as R-SLi), giving the SEI film higher ionic conductivity and improving the charging performance of the battery cell.

[0025] In some embodiments, equation (b) includes the structure shown in any one or more of equations (H-1) to (H-22):

[0026] Therefore, Z represents sulfur, which generates Li2S or organic polysulfides (such as R-SLi), giving the SEI film high ionic conductivity. The sulfur-containing additive has a high degree of freedom in its molecular chains, maintaining interfacial contact stability and improving the rate capability of the battery cell.

[0027] In some embodiments, in formula (b), R1 and R2 are connected in a ring, and Z is sulfur. Thus, Z is sulfur, generating Li2S or organic polysulfides, such as R-SLi, which gives the SEI film high ionic conductivity. This sulfur-containing additive has good stability, improving the rate capability and cycle life of the battery cell.

[0028] In some embodiments, equation (b) includes the structure shown in any one of equations (g) to (h):

[0029] Where n and m are integers, with n ranging from 1 to 4.

[0030] In some embodiments, equation (b) includes the structure shown in any one or more of equations (J-1) to (J-18):

[0031] In some embodiments, Z is oxygen, and the compound shown in formula (b) is a thioester additive, which includes the structure shown in any one or more of formulas (1) to (6):

[0032] 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.

[0033] In the embodiments of this application, the thioester additive is dispersed in an electrolyte containing 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 sulfur-containing electrolyte salt components and introduced into the SEI, thereby improving the dynamic performance of the battery cell while taking into account the cycle life of the battery cell.

[0034] In some embodiments, the sulfur-containing additive has a mass content of 0.001% to 10% in the electrolyte, optionally 0.5% to 2%. A mass content of the sulfur-containing 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.

[0035] In some embodiments, 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. The use of such groups in R1 and R2, compared to other groups substituted with heteroatoms, reduces side reactions such as corrosion of the battery cell, reduces the probability of the thioester additive releasing toxic gases under extreme conditions such as overheating or overcharging, and improves the reliability and cycle life of the battery cell.

[0036] In addition, R1 and R2 use the aforementioned groups, which are more easily degraded in the natural environment and cause less damage to the environment.

[0037] In some embodiments, the thioester additive comprises the structure shown in any one or more of formulas (I-1) to (I-42):

[0038] 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.

[0039] In some 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. An 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.

[0040] In some 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.

[0041] In some embodiments, the mass ratio of sulfur-containing additive to organic solvent is 1:(5-1000), optionally 1:(7.8-881). The organic solvent and thioester additive within the above range are beneficial for further reducing the transport energy barrier of active ions in the SEI film and improving the kinetic performance of the battery cell.

[0042] In some embodiments, the electrolyte salt includes a lithium salt, which includes one or more of lithium difluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium (trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium tetrafluorooxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluorooxalato)phosphate.

[0043] In some 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.

[0044] In some embodiments, the battery cell includes a negative electrode and a solid electrolyte membrane (SEI) located on the surface of the negative electrode. Based on the total mass of the solid electrolyte membrane, the solid electrolyte membrane includes 0.4% to 6.5% sulfur. This helps to reduce the transport energy barrier of active ions in the SEI membrane, allowing active ions to transport more easily within the SEI, thus improving the kinetic performance of the battery cell while maintaining its cycle life.

[0045] In some embodiments, the battery cell includes a negative electrode sheet, which includes a negative electrode active material. 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. The above-mentioned negative electrode materials, when combined with an electrolyte, can improve the performance of the battery cell.

[0046] In some embodiments, the electrolyte is an electrolyte solution with a conductivity of 10 to 20 mS / cm. -1 10 to 15 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.

[0047] In some embodiments, the electrolyte is a liquid electrolyte with a viscosity of 1 to 10 mPa·s, optionally 1.5 to 3.5 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 above viscosity also helps to balance the lithium deposition process, reduce dendrite formation, and improve the stability and cycle life of the battery cell.

[0048] In some 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.

[0049] In some embodiments, the present application provides a battery device including the battery cell of the first aspect. The battery device of the present application includes the battery cell of the first aspect, and therefore has at least the advantages of the battery cell or electrolyte.

[0050] Thirdly, embodiments of this application provide an electrical device that includes the battery device of the second aspect. The electrical device of this application includes the battery device of the second aspect, and therefore has at least the advantages corresponding to the battery device. Attached Figure Description

[0051] 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.

[0052] Figure 1 shows a schematic diagram of one embodiment of the battery cell of this application.

[0053] Figure 2 shows an exploded view of one embodiment of the battery cell shown in Figure 1.

[0054] Figure 3 shows an overall schematic diagram of a battery pack according to one embodiment of this application.

[0055] Figure 4 shows an exploded view of a battery pack according to one embodiment of this application.

[0056] Figure 5 shows a schematic diagram of one embodiment of an electrical device that uses the battery cell of this application as a power source.

[0057] 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.

[0058] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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).

[0066] 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.

[0067] In some 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.

[0068] A battery cell is the smallest unit that makes up a battery device, and it can independently perform the functions of charging and discharging. A 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 battery cell 5 as an example.

[0069] In some embodiments, individual battery cells can be assembled into a battery module. The number of 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 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 battery cells 5 can be fixed in place using fasteners.

[0070] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0071] In some 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.

[0072] 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.

[0073] In some embodiments, the battery device may be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0074] 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.

[0075] 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.

[0076] 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).

[0077] A single battery cell 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.

[0078] [Electrolytes]

[0079] In some embodiments, the battery cell further 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, or solid.

[0080] In some embodiments, the electrolyte comprises an electrolyte salt, an organic solvent, and a sulfur-containing additive, wherein the sulfur-containing additive comprises 0.001% to 10% by mass in the electrolyte, and the sulfur-containing additive comprises the structure shown in any one or more of formulas (a) to (b):

[0081] X, Y, W, and Z are each independently selected from any one of methylene, O, and S; and at least one of X, Y, W, and Z is a sulfur atom; R1, R2, R3, and R4 each independently include a hydrogen atom, an alkyl group with 1 to 10 unsubstituted or heteroatom-substituted carbon atoms, and an alkenyl group with 1 to 10 unsubstituted or heteroatom-substituted carbon atoms; wherein, in formula (a), R1 and R4 are connected to form a ring or not connected to form a ring, and R2 and R3 are connected to form a ring or not connected to form a ring; in formula (b), R1 and R2 are connected to form a ring or not connected to form a ring.

[0082] The heteroatom can be one or more of the following: halogen atom, sulfur atom, nitrogen atom, phosphorus atom, oxygen atom, and boron atom. The halogen atom can be one or more of the following: fluorine atom, chlorine atom, bromine atom, and iodine atom.

[0083] In this embodiment, the sulfur-containing additive is dispersed in an electrolyte containing electrolyte salt and organic solvent. The sulfur-containing additive can participate in the formation of the solid electrolyte interphase (SEI) membrane, improving the kinetic performance of the battery cell, such as rate capability and charging performance, while maintaining the cycle life of the individual cell. Studies have found that the relatively small mass content of the sulfur-containing additive in the electrolyte is beneficial for maintaining the viscosity and ionic conductivity of the electrolyte containing organic solvent. Furthermore, the binding energy ΔE (e.g., S-Li) between sulfur and active ions in the sulfur-containing additive is relatively low compared to other elements, such as oxygen, reducing the binding energy between sulfur 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 and also reduces the overall charging impedance Rct of the battery cell, improving charging performance.

[0084] In this embodiment, the sulfur-containing additive is dispersed in the electrolyte formed by the electrolyte salt and organic solvent. The sulfur-containing additive can participate in the formation of the solid electrolyte membrane (SEI membrane). That is, the sulfur-containing 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. This makes it easier for active ions to transport in the SEI, reduces the charging impedance Rct, and thus improves the dynamic performance of the battery cell, such as charging performance.

[0085] In related technologies, among the SEI film components, Li + The high diffusion barrier of the SEI film is unfavorable for the transport of active ions within the SEI. SEI films generally contain oxygen, and Li... + The binding element changes from oxygen to sulfur, increasing the sulfur content in the SEI film and reducing the affinity between the SEI film and Li. + The binding energy of Li is analyzed to be higher than that of sulfur (2.58). The higher the electronegativity, the stronger the attraction between the atom and the electron. This difference in electronegativity affects the binding energy of Li. + The electron cloud distribution of the anion and the strength of the ionic bond lead to the influence of Li + The binding energy with O is greater than that with Li + The binding energy with S is higher. The radius of a sulfur atom is larger than that of an oxygen atom, and because the electron cloud of sulfur is more dispersed, Li... + For S 2- The lower polarization results in weaker ionic bond strength and thus a lower binding energy, which in turn lowers the transport energy barrier of active ions in the SEI film and improves the kinetic performance of the battery cell.

[0086] It is understandable that the sulfur-containing additive can also be understood as a component or raw material of the electrolyte, and the mass content of the sulfur-containing additive in the electrolyte can be the content at the time of addition. The sulfur-containing additive can be added during the preparation of the electrolyte for the battery cell. After the battery cell undergoes electrochemical cycling, the content of the sulfur-containing additive may be low, extremely small, or even absent. The presence of the sulfur-containing additive can be detected from its products in the solid electrolyte membrane.

[0087] Specifically, after the battery cell is prepared or in the early stages of cycling, the sulfur-containing additives in the electrolyte may not have fully participated in the reaction. The presence and content of these additives can be confirmed using gas chromatography-mass spectrometry (GC-MS). As the battery cell is used, the content of sulfur-containing additives in the electrolyte may become extremely low, for example, decreasing to 0.005%, 0.003%, or even 0.001%, below the detection limit of conventional GC-MS. In this case, the presence and content of sulfur-containing additives can be confirmed using other more sophisticated instruments (such as infrared spectroscopy). Furthermore, as the battery cell is used, the sulfur-containing additives in the electrolyte may also be completely consumed. In this case, X-ray photoelectron spectroscopy (XPS) can be used to determine the sulfur products in the solid electrolyte membrane to confirm the use of sulfur-containing additives in the battery cell.

[0088] In some embodiments, the battery cell includes a negative electrode and a solid electrolyte membrane located on the surface of the negative electrode. Based on the total mass of the solid electrolyte membrane, the solid electrolyte membrane includes 0.4% to 6.5% sulfur, optionally 0.7% to 1.5%.

[0089] The solid electrolyte membrane (SEI) can include any value of sulfur from 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, and 6.5%. This helps to lower the transport energy barrier of active ions in the SEI membrane, allowing active ions to transport more easily within the SEI, thus improving the kinetic performance of the battery cells while maintaining their cycle life.

[0090] Determination of sulfur content in solid electrolyte membranes: Energy dispersive spectroscopy (EDS) was used to analyze solid electrolyte membrane samples at different locations, and the mass percentage of each element in each sample was analyzed and averaged. Specifically, after the battery cell was formed, the negative electrode and the surface solid electrolyte membrane were removed in a discharged state. The negative electrode includes a negative electrode material layer. The negative electrode material layer and the surface solid electrolyte membrane were taken as thin-film samples. Multiple thin-film samples from different locations were taken, and the mass percentage of sulfur in the thin-film samples was measured using EDS to determine the sulfur content in the solid electrolyte membrane.

[0091] The electrolyte contains this sulfur-containing additive. Among similar sulfur-containing additives, the higher the sulfur content in the additive, the better the cycle life and charging performance of the battery cell.

[0092] In some embodiments, the electrolyte is a liquid electrolyte, i.e., an electrolyte solution, which includes an electrolyte salt, a sulfur-containing additive, and an organic solvent.

[0093] In some embodiments, the sulfur-containing additive in the electrolyte has a mass content of 0.1% to 10%. It is understood that when preparing the electrolyte or disassembling an unformed battery cell, the sulfur-containing additive in the electrolyte may be within the above range, and when disassembling a formed battery cell, the sulfur-containing additive in the electrolyte may be 0.001% to 10%, optionally 0.001% to 6.8%.

[0094] Optionally, the mass content of the sulfur-containing additive in the electrolyte can be any value or a range thereof from 0.001%, 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, and 10%. A mass content of the sulfur-containing additive in the electrolyte 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. When the mass content of the sulfur-containing additive is higher than this range, it will affect the cycle life of the battery cell to some extent, potentially leading to a trade-off between charging performance and cycle life. When the mass content of sulfur-containing additives is less than 0.001%, the amount added is small, the impact on the SEI film is small, and thus the impact on the battery cells is small, and it cannot improve the charging performance of the battery cells.

[0095] In some embodiments, the sulfur-containing additive in the electrolyte has a mass content of 0.001% to 6.8%, optionally 0.032% to 6.8%. It is understood that when the formed battery cell is disassembled, the sulfur-containing additive in the electrolyte has a mass content of 0.001% to 6.8%. This allows the battery cell to balance cycle life and charging performance.

[0096] In addition, after 3 months of storage following formation, the mass content of sulfur-containing additives in the electrolyte of the battery cell is 0.001% to 2.5%, optionally 0.012% to 2.5%.

[0097] In some embodiments, in the structural formulas shown in formula (1) and / or formula (2), R1 and R2 independently include hydrogen atoms, alkyl or alkenyl groups with 1 to 6 carbon atoms substituted or unsubstituted with non-halogen atoms, optionally 2 to 4 alkyl or alkenyl groups. Therefore, the charging performance and cycle life of the battery cell are improved.

[0098] 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 sulfur-containing additives releasing toxic gases under extreme conditions such as overheating or overcharging, and improve the reliability and cycle life of battery cells.

[0099] In addition, R1 and R2 use the aforementioned groups, which are more easily degraded in the natural environment and cause less damage to the environment.

[0100] In some embodiments, in formula (a), R1 and R4 are not connected to form a ring, and R2 and R3 are not connected to form a ring. This indicates that the molecular chains in the sulfur-containing additive have a high degree of freedom and are easily spread uniformly on the electrode surface. This maintains interfacial contact stability and improves the charging performance and cycle life of the battery cell.

[0101] In some embodiments, the mass ratio of sulfur-containing additive to organic solvent is 1:(5-1000), and optionally 1:(7.8-881).

[0102] Optionally, the mass ratio of the sulfur-containing additive to the organic solvent 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 sulfur-containing additive in the electrolyte 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.

[0103] In some embodiments, the sulfur-containing additive comprises the structure shown in any one or more of formulas (1-1) to (1-15):

[0104] Therefore, the application of the aforementioned sulfur-containing additives to the electrolyte can improve the rate performance of individual battery cells.

[0105] In some embodiments, in formula (a), R1 and R4 are connected to form a ring and / or R2 and R3 are connected to form a ring.

[0106] Therefore, the sulfur-containing additive connected into rings has good stability and is suitable for high-voltage positive electrode sheets, such as NCM811 systems, taking into account both the charging performance and cycle life of the battery cell.

[0107] In some embodiments, equation (a) includes the structure shown in any one or more of equations (c) to (f):

[0108] Wherein, n, p, and q are each independent positive integers, and n, p, and q are each independent numbers from 1 to 4. Therefore, the connection of R1 and R4 into a ring and / or R2 and R3 into a ring in the sulfur-containing additive is beneficial for improving the cycle life of the battery cell while considering kinetics.

[0109] In some embodiments, in formula (c), the sulfur-containing additive comprises the structure shown in any one or more of formulas (3-1) to (3-25):

[0110] The above compounds contain a high amount of oxygen in the sulfur-containing additive, which can weaken the binding of Li with the solvent and promote the Li-Li bond. + Desolvation improves kinetic performance.

[0111] In some embodiments, in formula (d), the sulfur-containing additive comprises the structure shown in any one or more of formulas (4-1) to (4-22):

[0112] In some embodiments, in formula (e), the sulfur-containing additive comprises the structure shown in any one or more of formulas (5-1) to (5-25):

[0113] In some embodiments, in formula (f), the sulfur-containing additive comprises the structure shown in any one or more of formulas (6-1) to (6-25):

[0114] In some embodiments, in formula (b), R1 and R2 are not connected to form a ring, and Z is sulfur. Therefore, the reduction of the C=S bond generates Li2S or organic polysulfides (such as R-SLi), giving the SEI film higher ionic conductivity and improving the charging performance of the battery cell.

[0115] In some embodiments, equation (b) includes the structure shown in any one or more of equations (H-1) to (H-22):

[0116] Therefore, Z represents sulfur, which generates Li2S or organic polysulfides (such as R-SLi), giving the SEI film high ionic conductivity. The sulfur-containing additive has a high degree of freedom in its molecular chains, maintaining interfacial contact stability and improving the rate capability of the battery cell.

[0117] In some embodiments, equation (b) includes the structures shown in equations (K-3) to (K-4):

[0118] In some embodiments, in formula (b), R1 and R2 are connected in a ring, and Z is sulfur. Thus, Z is sulfur, generating Li2S or organic polysulfides, such as R-SLi, which gives the SEI film high ionic conductivity. This sulfur-containing additive has good stability, improving the rate capability and cycle life of the battery cell.

[0119] In some embodiments, equation (b) includes the structure shown in any one of equations (g) to (h):

[0120] Where n and m are integers, with n ranging from 1 to 4.

[0121] In some embodiments, equation (b) includes the structure shown in any one or more of equations (J-1) to (J-18):

[0122] In some embodiments, formula (g) includes the structure shown in any one of formulas (J-1) to (J-6).

[0123] In some embodiments, formula (h) includes the structure shown in any one of formulas (J-7) to (J-18).

[0124] In some embodiments, Z is oxygen, and the compound shown in formula (b) is a thioester additive, which includes the structure shown in any one or more of formulas (1) to (6):

[0125] 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.

[0126] 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.

[0127] 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.

[0128] In related technologies, among the SEI film components, Li + The high diffusion barrier of the SEI film is unfavorable for the transport of active ions within the SEI. SEI films generally contain oxygen, and Li... + The binding element changes from oxygen to sulfur, increasing the sulfur content in the SEI film and reducing the affinity between the SEI film and Li. + The binding energy of Li is analyzed to be higher than that of sulfur (2.58). The higher the electronegativity, the stronger the attraction between the atom and the electron. This difference in electronegativity affects the binding energy of Li. + The electron cloud distribution of the anion and the strength of the ionic bond lead to the influence of Li + The binding energy with O is greater than that with Li + The binding energy with S is higher. The radius of a sulfur atom is larger than that of an oxygen atom, and because the electron cloud of sulfur is more dispersed, Li... + For S 2- The lower polarization results in weaker ionic bond strength and thus a lower binding energy, which in turn lowers the transport energy barrier of active ions in the SEI film and improves the kinetic performance of the battery cell.

[0129] 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.

[0130] Electrolytes, including thioester additives, can also be understood as components or raw materials of electrolytes.

[0131] In some embodiments, the electrolyte is a liquid electrolyte, i.e., an electrolyte solution, which includes an electrolyte salt, a thioester additive, and an organic solvent.

[0132] In some embodiments, the thioester additive has a mass content of 0.001% to 10% in the electrolyte, optionally 0.5% to 2%.

[0133] Optionally, the mass content of the thioester additive in the electrolyte can be any value or a range thereof from 0.001%, 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, and 10%. 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.

[0134] In some embodiments, in formula (1) or formula (2), R1 and R2 independently comprise alkyl groups with 1 to 4 carbon atoms, substituted with hydrogen atoms, or unsubstituted with non-halogen atoms. Therefore, the reliability and cycle life of the battery cell are improved.

[0135] In some embodiments, R1 and R2 independently comprise hydrogen atoms and alkyl groups having 1 to 4 carbon atoms, respectively.

[0136] 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.

[0137] In addition, R1 and R2 use the aforementioned groups, which are more easily degraded in the natural environment and cause less damage to the environment.

[0138] In some embodiments, the thioester additive comprises the structure shown in any one or more of formulas (I-1) to (I-42):

[0139] 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.

[0140] For example, a solid electrolyte film exists at the interface between the negative electrode and the electrolyte. The solid electrolyte film includes sulfur-containing products formed by thioester additives, which further improves the kinetic performance of the battery cell.

[0141] In some embodiments, the thioester additive comprises the structure shown in formulas (K-1) to (K-2):

[0142] In some 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.

[0143] 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.

[0144] When the concentration of electrolyte salt 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.

[0145] In some embodiments, the organic solvent comprises 60% to 95% by mass of the electrolyte, optionally 80% to 88%.

[0146] 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.

[0147] In some embodiments, the mass ratio of thioester additive to organic solvent is 1:(5-1000), and optionally 1:(7.8-881).

[0148] Optionally, the mass ratio of the thioester additive to the organic solvent 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.

[0149] In some embodiments, the battery cell includes a solid electrolyte membrane and a negative electrode. The solid electrolyte membrane is located at the interface between the negative electrode and the electrolyte. The solid electrolyte membrane includes a lithium-containing product, which is 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 also lowers the transport energy barrier of active ions in the SEI membrane. 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.

[0150] In some embodiments, the electrolyte salt includes a lithium salt, which includes one or more of lithium difluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium (trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium tetrafluorooxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluorooxalato)phosphate.

[0151] In some 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.

[0152] In some embodiments, the electrolyte includes 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.

[0153] In some embodiments, the electrolyte includes a cation, which may include lithium ions, sodium ions, etc.

[0154] In some 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. Organic solvents may include carbonates, carboxylic esters, and ether solvents. Optionally, carbonates may include both cyclic carbonates and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0155] In some embodiments, the carbonate includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate.

[0156] In some embodiments, the carboxylic acid ester includes one or more of methyl formate, ethyl acetate, methyl butyrate, butyl acetate, and methyl propionate.

[0157] In some embodiments, the ether organic solvent includes one or more of 1,3-oxocyclopentane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 2-methyl-1,3-dioxolane, and 4-methyl-1,3-dioxolane.

[0158] 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 One or more of the following: decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether, 5-trifluoromethyl dodecylfluorohexyl methyl ether, 5-trifluoromethyl dodecylfluorohexyl ethyl ether, 5-trifluoromethyl dodecylfluorohexyl propyl ether, 6-trifluoromethyl tetradecafluoroheptyl methyl ether, 6-trifluoromethyl tetradecafluoroheptyl ethyl ether, 6-trifluoromethyl tetradecafluoroheptyl propyl ether, 7-trifluoromethyl hexadecylfluorooctyl methyl ether, 7-trifluoromethyl hexadecylfluorooctyl ethyl ether, and 7-trifluoromethyl hexadecylfluorooctyl propyl ether.

[0159] In some 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 rate capability and cycle life of the battery cell compared to ether solvents or carboxylic esters.

[0160] In some embodiments, the conductivity of the electrolyte is 10 to 20 mS / cm. -1 10 to 15 mS cm can be selected. -1 .

[0161] 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, and 20.0 mS / cm. The conductivity of the electrolyte reflects the migration ability of active ions within the electrolyte. The aforementioned conductivity can reduce the internal resistance of the battery cell, increase the charge transfer rate, improve rate performance, and enable the battery cell to maintain high energy output at high current densities. The aforementioned conductivity helps reduce uneven current distribution and improve the cycle life of individual battery cells.

[0162] 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.

[0163] In some embodiments, the viscosity of the electrolyte is 1 to 10 mPa·s, optionally 1.5 to 3.5 mPa·s.

[0164] 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, and 10.0 mPa·s. The viscosity of the electrolyte affects the diffusion rate of active ions within the electrolyte. Electrolyte viscosity within the above range helps to increase the diffusion coefficient of active ions, thereby accelerating charge transfer and improving the rate performance of the battery cell. Electrolytes with the above viscosities help to balance the lithium deposition process, reduce dendrite formation, and improve the stability and cycle life of the battery cell.

[0165] 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.

[0166] 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.

[0167] In some embodiments, the electrolyte may 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.

[0168] In some embodiments, the gel electrolyte comprises a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0169] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0170] 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.

[0171] 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.

[0172] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0173] 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.

[0174] 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.

[0175] 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 located at 1000-1200 cm⁻¹. -1 Within the range. By using high-resolution gas chromatography-high-resolution mass spectrometry, different components in the electrolyte can be separated and their molecular weights can be obtained with high precision, thereby determining the atomic composition; then, the specific molecular structure of each component can be confirmed by nuclear magnetic resonance spectroscopy results.

[0176] 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.

[0177] 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.

[0178] [Positive electrode plate]

[0179] In some embodiments, the positive electrode sheet 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.

[0180] 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.

[0181] 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.

[0182] 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.).

[0183] 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.

[0184] In some embodiments, the positive electrode active material comprises a lithium transition metal oxide. Examples may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide 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 0.8 Co0.1 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.

[0185] In some 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.

[0186] 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.

[0187] As an example, positive electrode active materials may include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 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.

[0188] 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.

[0189] 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.

[0190] In some 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.

[0191] In some embodiments, the positive electrode active material film layer may 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.

[0192] In some embodiments, the positive electrode active material film layer may 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.

[0193] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. 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).

[0194] 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.

[0195] [Negative electrode plate]

[0196] In some embodiments, the negative electrode may include a negative current collector.

[0197] 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.).

[0198] In some 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.

[0199] 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.

[0200] 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.

[0201] In some 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.

[0202] 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.

[0203] In some 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.

[0204] As an example, negative electrode active materials can be filled or / and deposited within the negative electrode current collector.

[0205] In some embodiments, the negative electrode current collector can be made of copper.

[0206] 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.

[0207] For example, when the battery cell is a sodium battery cell, in some embodiments, the negative electrode sheet may include a sodium sheet or a sodium alloy sheet. In some embodiments, the metallic material in the first metal layer may include one or more of elemental lithium and lithium alloys. The lithium alloy may be an alloy formed by metallic lithium with other metallic or non-metallic elements. As an example, other metallic elements in the lithium alloy may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, and non-metallic elements in the lithium alloy may include one or more of boron, carbon, and silicon.

[0208] [Isolation Component]

[0209] In some 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, and any known porous membrane with good chemical and mechanical stability can be selected.

[0210] 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.

[0211] 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.

[0212] In some 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.

[0213] Methods for preparing battery cells are well known. In some 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 packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained. Multiple battery cells can further be 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 embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0214] Electrical appliances

[0215] This application provides an electrical device, including the battery device described above.

[0216] 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.

[0217] Electrical devices can be equipped with individual battery cells, battery modules, or battery packs depending on their usage requirements. Figure 5 is a schematic diagram of an example electrical device, such as 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.

[0218] 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.

[0219] Example

[0220] 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.

[0221] Example 1

[0222] Electrolyte preparation: Ethyl carbonate, diethyl carbonate, and dimethyl carbonate, organic solvents, are mixed in a volume ratio of 1:1:1; LiPF6 is dissolved in the above solution at a concentration of 1 mol / L. Based on the final total mass of the electrolyte, a thioester additive, namely ethyl thioester, is added at a mass fraction of 1% to obtain the electrolyte.

[0223] Preparation of battery cells:

[0224] 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.

[0225] Preparation of negative electrode sheet: Graphite, conductive carbon black, aqueous dispersant sodium carboxymethyl cellulose (CMC), and aqueous binder styrene-butadiene latex (SBR) are mixed evenly in a weight ratio of 95:1:1:3, and then 100 parts by weight of solvent water is added to obtain a 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.

[0226] Preparation of the separator: A polyethylene film with a thickness of 12 μm was used as the separator.

[0227] Assembly: Place the electrodes in the order of "positive electrode - separator - negative electrode - separator - positive electrode", inject the electrolyte mentioned above, and obtain a stacked battery. The positive active material film layer of the positive electrode is set to face the separator.

[0228] Examples 2-4

[0229] 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.

[0230] Examples 5-10

[0231] 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.

[0232] Examples 11-12

[0233] 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).

[0234] Examples 13-16

[0235] 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.

[0236] Examples 17-18

[0237] The preparation method is similar to that of Example 1, except that the organic solvent in the electrolyte is different. In Examples 17-18, the organic solvent is replaced with ethylene glycol dimethyl ether or methyl acetate, respectively. The mass content of the sulfur-containing additive remains unchanged compared with Example 1, which is 1%, and the concentration of LiPF6 is 1 mol / L, as shown in Table 2.

[0238] Example 19

[0239] The preparation method is similar to that in Example 1, except that the composition of the organic solvent in the electrolyte is different, the dimethyl carbonate in the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether, and the concentration of LiPF6 is 1 mol / L, as shown in Table 2.

[0240] Example 20

[0241] The preparation method is similar to that in Example 19, except that the composition of the organic solvent in the electrolyte is different, the diethyl carbonate in the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether, and the concentration of LiPF6 is 1 mol / L, as shown in Table 2.

[0242] Comparative Example 1

[0243] 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 1 mol / L, as shown in Table 1.

[0244] Comparative Example 2

[0245] The preparation method is similar to that in Example 1, except that the mass ratio of the thioester additive to the organic solvent in the electrolyte is different. The mass ratio of the thioester additive to the organic solvent is 1:1.88. The organic solvent is obtained by mixing ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The mass content of the thioester additive in the electrolyte is 30%, and the concentration of LiPF6 is 1 mol / L, as shown in Table 2.

[0246] Example 21

[0247] The preparation method is similar to that of Example 1, except that the type of sulfur-containing additive is different. The thioester additive in Example 1 is replaced with an equal mass of sulfur-containing additive formula (1-1), as shown in Table 3.

[0248] Examples 22-23

[0249] The preparation method is similar to that of Example 21, except that the mass of sulfur-containing additive added to the electrolyte is different. When preparing the electrolyte, the content of sulfur-containing additive formula (1-1) of Example 21 in the electrolyte is 0.1% and 10% respectively, as shown in Table 3.

[0250] Examples 24 to 34

[0251] The preparation method is similar to that of Example 21, except that the type of sulfur-containing additive is different. The sulfur-containing additive formula (1-1) of Example 21 is replaced with other types of sulfur-containing additives of equal mass, as shown in Table 3.

[0252] Examples 35 to 36

[0253] The preparation method is similar to that in Example 34, except that the mass content of the sulfur-containing additive in the electrolyte is different. The content of the sulfur-containing additive (H-1) in the electrolyte is 0.1% and 10% respectively, as shown in Table 3.

[0254] Examples 37 to 43

[0255] The preparation method is similar to that of Example 21, except that the type of sulfur-containing additive is different. The sulfur-containing additive formula (1-1) of Example 21 is replaced with other types of sulfur-containing additives of equal mass, as shown in Table 3.

[0256] Examples 44-45

[0257] The preparation method is similar to that of Example 1, except that the type of sulfur-containing additive is different. The thioester additive in Example 1 is replaced with an equal mass of other types of sulfur-containing additives. The structure of Example 44 is shown in formula (K-3); the structure of Example 45 is shown in formula (K-4), see Table 3.

[0258] Comparative Examples 3-8

[0259] The preparation methods are similar to those in Examples 21, 25, 29, 34, and 41, except that the mass ratio of sulfur-containing additive to organic solvent in the electrolyte is different, with a mass ratio of 1:88.07. The types and volume composition of organic solvents in Comparative Examples 3-8 are the same, and the organic solvents are obtained by mixing ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. The mass content of sulfur-containing additive in the electrolyte is 30%, and the concentration of LiPF6 is 1 mol / L, as shown in Table 4.

[0260] Examples 46-47

[0261] The preparation method is similar to that in Example 34, except that the organic solvent in the electrolyte is different. In Example 46, the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether, and in Example 47, the organic solvent is replaced with an equal volume of methyl acetate. The concentration of LiPF6 is 1 mol / L, as shown in Table 5.

[0262] Example 48

[0263] The preparation method is similar to that of Example 34, except that the composition of the organic solvent in the electrolyte is different, the dimethyl carbonate in the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether, the concentration of LiPF6 is 1 mol / L, and the mass content of the sulfur-containing additive remains unchanged from that in Example 34, which is 1% (see Table 5).

[0264] Example 49

[0265] The preparation method is similar to that in Example 34, except that the composition of the organic solvent in the electrolyte is different, the diethyl carbonate in the organic solvent is replaced with an equal volume of ethylene glycol dimethyl ether, and the concentration of LiPF6 is 1 mol / L, as shown in Table 5.

[0266] Test section

[0267] 1. Battery Cell Cycle Life Testing: 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 initial discharge capacity is defined as the cycle life of the battery cell.

[0268] 2. Charging performance testing of individual battery cells at 25℃:

[0269] Capacity calibration:

[0270] 1) In the examples or comparative examples, the positive electrode, negative electrode, separator, and electrolyte are used to prepare a stacked three-electrode battery, which is then left to stand at 25°C for 30 minutes.

[0271] 2) At 25℃, charge the battery cell to the upper limit of the charging voltage of 3.8V at 0.33C, and then continue to charge at the upper limit of the charging voltage until the current is 0.05C, and then charge to stop (where C represents the rated capacity of the battery cell). Let it stand at 25℃ for 1 hour.

[0272] 3) Discharge the battery cell to the cutoff voltage of 2.0V at 0.33C at 25℃, record the total discharge capacity C0 of the battery cell, and let it stand at 25℃ for 1 hour.

[0273] 25℃ charging test:

[0274] 1) Prepare a stacked three-electrode battery using the positive electrode, negative electrode, separator, and electrolyte from the examples or comparative examples, and let it stand for 30 minutes;

[0275] 2) At 25℃, discharge with 0.33C0 DC to the cutoff voltage of 2.0V, at which point the state of charge (SOC) is 0%.

[0276] 3) Charge the battery with a constant current of 7C0 until the negative electrode potential is 0mV, and read the capacity C1 at this time. At this time, the corresponding SOC1 = C1 / C0.

[0277] 4) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0278] 5) Charge the battery with a constant current of 6C0 until the negative electrode potential is 0mV, and read the capacity C2 at this time. The corresponding SOC2 = C2 / C0 at this time.

[0279] 6) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0280] 7) Charge the battery with a constant current of 5C0 until the negative electrode potential is 0mV, and read the capacity C3 at this time. The corresponding SOC3 is C3 / C0.

[0281] 8) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0282] 9) Charge the battery with a constant current of 4C0 until the negative electrode potential is 0mV, and read the capacity C4 at this time. The corresponding SOC4 is C4 / C0.

[0283] 10) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0284] 11) Charge the battery with a constant current of 3C0 until the negative electrode potential is 0mV, and read the capacity C5 at this time. The corresponding SOC5 is C5 / C0.

[0285] 12) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0286] 13) Charge the battery with a constant current of 2.5C0 until the negative electrode potential is 0mV, and read the capacity C6 at this time. The corresponding SOC6 is C6 / C0.

[0287] 14) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0288] 15) Charge the battery with a constant current of 2C0 until the negative electrode potential is 0mV, and read the capacity C7 at this time. The corresponding SOC7 is C7 / C0.

[0289] 16) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0290] 17) Charge the battery with a constant current of 1.8C0 until the negative electrode potential is 0mV, and read the capacity C8 at this time. The corresponding SOC8 is C8 / C0.

[0291] 18) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0292] 19) Charge the battery with a constant current of 1.6C0 until the negative electrode potential is 0mV, and read the capacity C9 at this time. The corresponding SOC9 = C9 / C0 at this time.

[0293] 20) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V is reached;

[0294] 21) Charge the battery with a constant current of 1.4C0 until the negative electrode potential is 0mV, and read the capacity C10 at this time. The corresponding SOC10 = C10 / C0 at this time.

[0295] 22) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V is reached;

[0296] 23) Charge the battery with a constant current of 1.2C0 until the negative electrode potential is 0mV, and read the capacity C11 at this time. The corresponding SOC11 is C11 / C0.

[0297] 24) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V is reached;

[0298] 25) Charge the battery with a constant current of 1C0 until the negative electrode potential is 0mV, and read the capacity C12 at this time. The corresponding SOC12 is C12 / C0.

[0299] 26) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0300] 27) Charge the battery with a constant current of 0.8C0 until the negative electrode potential is 0mV, and read the capacity C13 at this time. The corresponding SOC13 is C13 / C0.

[0301] 28) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V is reached;

[0302] 29) Charge the battery with a constant current of 0.6C0 until the negative electrode potential is 0mV, and read the capacity C14 at this time. The corresponding SOC14 is C14 / C0.

[0303] 30) Discharge at a constant current of 0.33C0 until the cutoff voltage of 2.0V;

[0304] 31) Charge the battery with a constant current of 0.4C0 until the negative electrode potential is 0mV, and read the capacity C15 at this time. The corresponding SOC15 is C15 / C0.

[0305] Dividing different SOC ranges by different charging rates yields the charging time for each SOC range, i.e., T1 = (SOC2 - SOC1) / 6, T2 = (SOC3 - SOC2) / 5, T3 = (SOC4 - SOC3) / 4, T4 = (SOC5 - SOC4) / 3, T5 = (SOC6 - SOC5) / 2.5, T6 = (SOC7 - SOC6) / 2, T7 = (SOC8 - SOC7) / 1.8, T8 = (SOC9 - SOC8) / 1.6, T9 = (SOC10 - SOC9) / 1.4, T10 = (SOC11 - SOC2) / 2.5, T10 = (SOC10 ... The charging times are calculated as follows: T1 = (SOC10) / 1.2, T11 = (SOC12-SOC11) / 1, T12 = (SOC13-SOC12) / 0.8, T13 = (SOC14-SOC13) / 0.6, T14 = (SOC15-SOC14) / 0.4. The total charging time T is obtained by summing the above charging times, i.e., T = T1 + T2 + T3 + T4 + T5 + T6 + T7 + T8 + T9 + T10 + T11 + T12 + T13 + T14. The equivalent charging rate is (SOC15-SOC1) / T. The charging capability is evaluated by the magnitude of the equivalent charging rate.

[0306] 3. Charging performance testing of individual battery cells at -10℃:

[0307] Capacity calibration:

[0308] 1) In the examples or comparative examples, the positive electrode, negative electrode, separator, and electrolyte are used to prepare a stacked three-electrode battery, which is then left to stand at 25°C for 30 minutes.

[0309] 2) At 25℃, charge the battery cell to the upper limit of the charging voltage of 3.8V at 0.33C, and then continue to charge at the upper limit of the charging voltage until the current is 0.05C, and then charge to stop (where C represents the rated capacity of the battery cell). Let it stand at 25℃ for 1 hour.

[0310] 3) Discharge the battery cell to the cutoff voltage of 2.0V at 0.33C at 25℃, record the total discharge capacity C0 of the battery cell, and let it stand at 25℃ for 1 hour.

[0311] -10℃ charging test:

[0312] 1) Prepare a stacked three-electrode battery using the positive electrode, negative electrode, separator, and electrolyte from the examples or comparative examples, and let it stand for 30 minutes;

[0313] 2) At 25℃, discharge with 0.33C0 DC to the cutoff voltage of 2.0V, at which point the state of charge (SOC) is 0%.

[0314] 3) Let it stand at -10℃ for 1 hour, then charge it with a constant current of 1.5C0 until the negative electrode potential is 0mV. Read the capacity C1 at this time. At this time, the corresponding SOC1 = C1 / C0.

[0315] 4) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0316] 5) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 1.0C0 until the negative electrode potential is 0mV, and read the capacity C2 at this time. At this time, the corresponding SOC2=C2 / C0;

[0317] 6) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0318] 7) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.8C0 until the negative electrode potential is 0mV, and read the capacity C3 at this time. At this time, the corresponding SOC3 = C3 / C0.

[0319] 8) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0320] 9) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.6C0 until the negative electrode potential is 0mV, and read the capacity C4 at this time. At this time, the corresponding SOC4 = C4 / C0.

[0321] 10) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0322] 11) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.5C0 until the negative electrode potential is 0mV, and read the capacity C5 at this time. At this time, the corresponding SOC5 = C5 / C0.

[0323] 12) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0324] 13) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.4C0 until the negative electrode potential is 0mV, and read the capacity C6 at this time. At this time, the corresponding SOC6 = C6 / C0.

[0325] 14) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0326] 15) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.35C0 until the negative electrode potential is 0mV, and read the capacity C7 at this time. At this time, the corresponding SOC7 = C7 / C0.

[0327] 16) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0328] 17) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.30C0 until the negative electrode potential is 0mV, and read the capacity C8 at this time. At this time, the corresponding SOC8 = C8 / C0.

[0329] 18) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0330] 19) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.25C0 until the negative electrode potential is 0mV, and read the capacity C9 at this time. At this time, the corresponding SOC9 = C9 / C0.

[0331] 20) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0332] 21) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.20C0 until the negative electrode potential is 0mV, and read the capacity C10 at this time. At this time, the corresponding SOC10 = C10 / C0.

[0333] 22) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0334] 23) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.15C0 until the negative electrode potential is 0mV, and read the capacity C11 at this time. At this time, the corresponding SOC11=C11 / C0;

[0335] 24) Adjust the temperature to 25℃, let it stand for 2 hours, and discharge it with a constant current of 0.33C0 until the cutoff voltage is 2.0V;

[0336] 25) Adjust the temperature to -10℃, let it stand for 2 hours, charge it with a constant current of 0.10C0 until the negative electrode potential is 0mV, and read the capacity C12 at this time. At this time, the corresponding SOC12 = C12 / C0.

[0337] Dividing different SOC ranges by different charging rates yields the charging time for each SOC range, specifically: T1 = (SOC2 - SOC1) / 1, T2 = (SOC3 - SOC2) / 0.8, T3 = (SOC4 - SOC3) / 0.6, T4 = (SOC5 - SOC4) / 0.5, T5 = (SOC6 - SOC5) / 0.4, T6 = (SOC7 - SOC6) / 0.35, T7 = (SOC8 - SOC7) / 0.3, T8 = (SOC9 - SOC2) / 0.35, T9 = (SOC2 - SOC1) / 0.4, T1 ... The total charging time T is calculated by summing the above charging times: T = (SOC10-SOC9) / 0.25, T9 = (SOC10-SOC9) / 0.2, T10 = (SOC11-SOC10) / 0.15, and T11 = (SOC12-SOC11) / 0.1. The total charging time T is calculated as T = T1 + T2 + T3 + T4 + T5 + T6 + T7 + T8 + T9 + T10 + T11. The equivalent charging rate is calculated as (SOC12-SOC1) / T. The charging capability is evaluated based on the magnitude of the equivalent charging rate.

[0338] 4. Detection of the mass content of sulfur-containing additives in the electrolyte: The battery cells of the above examples or comparative examples were formed, the battery cells were disassembled, and electrolyte samples were obtained. The sulfur-containing additive components in the electrolyte were detected by gas chromatography-mass spectrometry.

[0339] After the battery cells in the above embodiments or comparative examples are formed, they are stored at 25°C for 3 months. The battery cells are then disassembled to obtain electrolyte samples. The content of sulfur-containing additives in the electrolyte is detected by gas chromatography-mass spectrometry to obtain the mass content of sulfur-containing additives in the electrolyte after 3 months of storage following formation.

[0340] The test results are shown in Tables 1 to 5.

[0341] As shown in Table 1, compared with Comparative Examples 1-2, Examples 1-16 added the aforementioned amount of thioester additive to the electrolyte, enabling the battery cells to balance charging performance and cycle life. Charging performance includes both high-temperature and low-temperature charging performance. Comparative Example 1 did not add thioester additive, which is equivalent to adding less than 0.001%. Comparative Example 2 added 30% thioester additive. The mass content of thioester additive in Comparative Examples 1-2 is outside the range of 0.001% to 10% in this application's embodiments, and the battery cells in the comparative examples cannot balance charging performance and cycle life. Therefore, adding an appropriate amount of thioester additive to the electrolyte of the battery cells in this application's embodiments is beneficial for achieving a balance between charging performance and cycle life.

[0342] 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.

[0343] As shown in Table 2, compared with Examples 17-20, carbonate organic solvents 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.

[0344] As shown in Table 3, compared with Comparative Example 1, Examples 21-45 added sulfur-containing additives of the above-mentioned quality, which enabled the battery cells to balance charging performance and cycle life.

[0345] As shown in Table 3, compared with Example 34, the sulfur-containing additives that are not replaced by halogen atoms can further improve the cycle life of the battery cells in the electrolyte compared with the sulfur-containing additives that are replaced by halogen atoms.

[0346] As shown in Table 4, compared to Comparative Example 3, Example 25 to Comparative Example 4, Example 27 to Comparative Example 5, Example 29 to Comparative Example 6, Example 34 to Comparative Example 7, and Example 41 to Comparative Example 8, the sulfur-containing additives in the examples had relatively low content in the electrolyte. When added as an additive rather than as a solvent with a higher volume or mass, the examples exhibited better cycle life. The reason for this is that the main function of the sulfur-containing additive is to modify the SEI film or electrolyte interface, rather than to provide an ion transport medium. A small amount of sulfur-containing additive can play a crucial role; excessive sulfur-containing additive can lead to an excessively thick SEI, increasing internal resistance or deteriorating the physicochemical properties of the electrolyte, or affecting cycle life.

[0347] As shown in Table 5, compared with Examples 46-49, Examples 21-45 show that carbonate organic solvents further improve the cycle life of battery cells compared with ether solvents and carboxylic esters.

[0348] 5. Determination of Sulfur Content in Solid Electrolyte Membrane: After disassembling the formed battery cell, the negative electrode and the solid electrolyte membrane on its surface were removed under discharge. The negative electrode includes a negative electrode material layer. The negative electrode material layer and the solid electrolyte membrane on its surface were used as thin-film samples. Multiple thin-film samples from different locations were taken, and the mass percentage of sulfur in the thin-film samples was measured using EDS to determine the sulfur content in the solid electrolyte membrane. The sulfur content in the solid electrolytes of Examples 1-4 and Comparative Examples 1-2 was determined, and the results are shown in Table 6.

[0349] Table 6

[0350] As shown in Table 6, adding different amounts of thioester additives to the electrolyte resulted in different masses of thioester additives participating in the formation of the solid electrolyte membrane. The mass content of sulfur in the solid electrolyte membrane varied. In Examples 1-4, the mass content of sulfur in the solid electrolyte membrane was appropriate, which was beneficial for the battery cells to balance cycle life and charging performance. In Comparative Example 1, the mass content of sulfur in the solid electrolyte membrane was relatively low, which affected the charging performance of the battery cells. In Comparative Example 2, the mass content of sulfur in the solid electrolyte membrane was also relatively low, which affected the charging performance and cycle life of the battery cells.

[0351] 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, wherein, The electrolyte comprises an electrolyte salt, an organic solvent, and a sulfur-containing additive, wherein the sulfur-containing additive is present in the electrolyte at a mass content of 0.001% to 10%, and the sulfur-containing additive comprises a structure shown in any one or more of formulas (a) to (b): X, Y, W, and Z are each independently selected from any one of methylene, O, and S; and at least one of X, Y, W, and Z is a sulfur atom; R1, R2, R3, and R4 each independently include a hydrogen atom, an alkyl group with 1 to 10 unsubstituted or heteroatom-substituted carbon atoms, and an alkenyl group with 1 to 10 unsubstituted or heteroatom-substituted carbon atoms; wherein, in formula (a), R1 and R4 are connected to form a ring or not connected to form a ring, and R2 and R3 are connected to form a ring or not connected to form a ring; in formula (b), R1 and R2 are connected to form a ring or not connected to form a ring.

2. The battery cell according to claim 1, wherein, In equation (a), R1 and R4 are not connected to form a loop, and R2 and R3 are not connected to form a loop.

3. The battery cell according to claim 1 or 2, wherein, The sulfur-containing additive comprises the structure shown in any one or more of formulas (1-1) to (1-15):

4. The battery cell according to claim 1, wherein, In equation (a), R1 and R4 are connected to form a loop and / or R2 and R3 are connected to form a loop.

5. The battery cell according to claim 1 or 4, wherein, Equation (a) includes the structure shown in any one or more of equations (c) to (f): Where n, p, and q are all independent positive integers, and n, p, and q are all independent numbers from 1 to 4.

6. The battery cell according to any one of claims 1, 4, and 5, wherein, In formula (c), the sulfur-containing additive comprises the structure shown in any one or more of formulas (3-1) to (3-25):

7. The battery cell according to any one of claims 1, 4, and 5, wherein, In formula (d), the sulfur-containing additive comprises the structure shown in any one or more of formulas (4-1) to (4-22):

8. The battery cell according to any one of claims 1, 4 and 5, wherein, In formula (e), the sulfur-containing additive comprises the structure shown in any one or more of formulas (5-1) to (5-25):

9. The battery cell according to any one of claims 1, 4 and 5, wherein, In formula (f), the sulfur-containing additive comprises the structure shown in any one or more of formulas (6-1) to (6-25):

10. The battery cell according to claim 1, wherein, In equation (b), R1 and R2 are not connected to form a ring, and Z is sulfur.

11. The battery cell according to claim 1 or 10, wherein, Equation (b) includes the structure shown in any one or more of equations (H-1) to (H-22):

12. The battery cell according to claim 1, wherein, In equation (b), R1 and R2 are connected to form a ring, and Z is sulfur.

13. The battery cell according to claim 1 or 12, wherein, Equation (b) includes the structure shown in any one of equations (g) to (h): Where n and m are integers, with n ranging from 1 to 4.

14. The battery cell according to any one of claims 1, 12 to 13, wherein, Equation (b) includes the structure shown in any one or more of equations (J-1) to (J-18):

15. The battery cell according to claim 1, wherein, Z represents oxygen, and the compound shown in formula (b) is 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.

16. The battery cell according to claim 15, wherein, 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.

17. The battery cell according to claim 15 or 16, wherein, The thioester additive comprises the structure shown in any one or more of formulas (I-1) to (I-42):

18. The battery cell according to any one of claims 1 to 17, wherein, The sulfur-containing additive in the electrolyte has a mass content of 0.1% to 10%; and / or, The sulfur-containing additive has a mass content of 0.032% to 6.8% in the electrolyte.

19. The battery cell according to any one of claims 1 to 18, wherein, 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 sulfur-containing additive to the organic solvent is 1:(5-1000).

20. The battery cell according to any one of claims 1 to 19, wherein, 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 sulfur-containing additive to the organic solvent is 1:(7.8~881).

21. The battery cell according to any one of claims 1 to 20, wherein, The electrolyte satisfies one or more of the following conditions: 1) The electrolyte salt includes lithium salts, which include 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.

22. The battery cell according to any one of claims 1 to 21, wherein, 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 20 mS / cm. -1 ; 2) The viscosity of the electrolyte is 1 to 10 mPa·s.

23. The battery cell according to any one of claims 1 to 22, wherein, 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 15 mS / cm. -1 ; 2) The viscosity of the electrolyte is 1.5 to 3.5 mPa·s.

24. The battery cell according to any one of claims 1 to 23, wherein, The battery cell includes a negative electrode and a solid electrolyte membrane located on the surface of the negative electrode, wherein the solid electrolyte membrane contains 0.4% to 6.5% sulfur.

25. The battery cell according to any one of claims 1 to 24, wherein, The battery cell includes a negative electrode sheet, and the negative electrode sheet 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.

26. The battery cell according to any one of claims 1 to 25, wherein, 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.

27. A battery device, wherein, Includes the battery cell described in any one of claims 1 to 26.

28. An electrical appliance, wherein, Includes the battery device as described in claim 27.

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