Battery cell, battery device and electric device

Abstract

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive pole piece, and the positive pole piece comprises a positive current collector and a tab extending out of the positive current collector; the insulating coating is positioned on one side, close to the tab, of the surface of the positive current collector, and the insulating coating contains a binder; wherein the binder has a first structural unit containing a benzene ring and a second structural unit containing a polyolefin chain segment. The bonding agent provided by the invention can improve the strength and toughness of the insulating coating, so that the reliability of the battery monomer is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a battery cell, a battery device, and an electrical device. Background Technology

[0002] Battery cells are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric car toys, electric toy ships, electric toy airplanes, and power tools.

[0003] In the development of battery cells, improving the reliability of battery cells is one of the most pressing issues to be addressed. Summary of the Invention

[0004] This application provides a battery cell, a battery device, and an electrical device to improve the reliability of the battery cell.

[0005] In a first aspect, embodiments of this application provide a battery cell, including a positive electrode sheet, wherein the positive electrode sheet comprises:

[0006] A positive current collector, and a tab extending from the positive current collector;

[0007] An insulating coating is located on the surface of the positive current collector near the tab, and the insulating coating comprises an adhesive; wherein,

[0008] The adhesive has a first structural unit containing a benzene ring and a second structural unit containing a polyolefin segment.

[0009] According to the embodiments of this application, the first structural unit containing benzene rings in the binder, as a rigid chain segment, can act as an anchor point and provide high mechanical strength, giving the insulating coating good tensile strength properties. The second structural unit containing polyolefin chain segments in the binder, as a flexible link, can provide good toughness, giving the insulating coating good ductility and flexibility. Through the cooperation of the first and second structural units in the binder, the insulating coating can have both high mechanical strength and good flexibility, which can reduce problems such as breakage caused by rolling and bending during electrode processing. This can reduce the risk of fire or explosion caused by internal short circuits in battery cells and improve the reliability of battery cells.

[0010] In some embodiments, the molar content of the first structural unit in the adhesive molecule is 20% to 50%, and the molar content of the second structural unit is 50% to 80%.

[0011] In some embodiments, the first structural unit has the structural formula shown in equation (I):

[0012]

[0013] In formula (I),

[0014] R1 is selected from Or polymers formed from the above monomers;

[0015] X1 and X2 are each independently selected from -CONH- or -CO-.

[0016] In some embodiments, the second structural unit has the structural formula shown in formula (II):

[0017]

[0018] In formula (II),

[0019] X3 and X4 are each independently selected from -O- or -NH-;

[0020] R2 has the structure shown in equation (II-1):

[0021]

[0022] In equation (II-1),

[0023] R3 is selected from phenyl or substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms;

[0024] Both m and n are integers, and 200≤m≤5000, 0≤n≤5000.

[0025] In some embodiments, 0 ≤ n / m ≤ 5.

[0026] In some embodiments, the adhesive has a structural formula as shown in formula (III):

[0027]

[0028] In formula (III),

[0029] R1 is selected from Or polymers formed from the above monomers;

[0030] R3 is selected from phenyl or substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms;

[0031] X1 and X2 are each independently selected from -CONH- or -CO-;

[0032] X3 and X4 are each independently selected from -O- or -NH-;

[0033] a, b, and c are all integers, and 0.2≤a / (a+b+c)≤0.5, 0.2≤b / (a+b+c)≤0.8, and 0≤c / (a+b+c)≤0.5.

[0034] In some embodiments, the weight-average molecular weight of the adhesive is between 300,000 and 1,500,000.

[0035] In some embodiments, the adhesive in the insulating coating comprises 20% to 80% by mass.

[0036] In some embodiments, the insulating coating further includes insulating powder, wherein the mass percentage of the insulating powder in the insulating coating is 20% to 80%.

[0037] In some embodiments, the insulating powder comprises one or more of metal oxides, metal hydroxides, and inorganic silicates.

[0038] In some embodiments, the thickness of the insulating coating on one side is 10 μm to 50 μm.

[0039] In some embodiments, the tensile strength of the insulating coating is 40 MPa to 80 MPa.

[0040] In some embodiments, the elongation at break of the insulating coating is 50% to 105%.

[0041] In some embodiments, the peel strength of the insulating coating is 50 N / m to 70 N / m.

[0042] In some embodiments, the swelling rate of the insulating coating in a carbonate solvent is 10% to 50%.

[0043] Secondly, embodiments of this application provide a battery device, including a single battery cell from the first aspect of this application.

[0044] Thirdly, embodiments of this application provide an electrical device, including a single cell according to the first aspect of this application or a battery device according to the second aspect of this application, wherein the single cell or the battery device is used to store or provide electrical energy. Attached Figure Description

[0045] 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 introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0047] Figure 2 This is an exploded schematic diagram of a battery provided for some embodiments of this application.

[0048] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0049] Figure 4 This is a planar schematic diagram of the positive electrode sheet in some embodiments of this application.

[0050] The accompanying drawings are not necessarily drawn to scale.

[0051] The reference numerals in the attached drawings are explained as follows: 1. Vehicle; 2. Battery unit; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Receiving space; 6. Battery module; 7. Battery cell; 8. Positive electrode plate; 81. Tab; 82. Positive electrode film; 83. Insulating coating. Detailed Implementation

[0052] The embodiments of this application are hereby disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0053] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. 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 "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] 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.

[0055] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0056] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates 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.

[0057] Unless otherwise specified, the terms "connected" and "linked" in this application should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0058] In this application, "multiple" refers to two or more, including two. "Multiple types" refers to two or more, including two.

[0059] The battery apparatus 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 connected in series, parallel, or mixed connections via a busbar.

[0060] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0061] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0062] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0063] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0064] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0065] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0066] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0067] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0068] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0069] Electrical devices can choose the type of battery according to their usage needs, such as individual battery cells, battery modules, or battery packs.

[0070] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0071] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0072] like Figure 1 As shown, a battery device 2 is installed inside the vehicle 1. The battery device 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0073] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0074] In some embodiments, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0075] Figure 2 This is an exploded schematic diagram of a battery device provided in some embodiments of this application. For example... Figure 2 As shown, the battery device 2 includes a housing 5 and battery cells (not shown), with the battery cells housed within the housing 5.

[0076] The housing 5 is used to house individual battery cells, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the individual battery cells. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as cylinders, cuboids, etc.

[0077] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0078] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0079] In battery device 2, there can be one or more battery cells. If there are multiple battery cells, they can be connected in series, in parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells are connected in both series and parallel configurations. Multiple battery cells can be directly connected in series, in parallel, or in a mixed configuration, and then the whole assembly of multiple battery cells is housed in housing 5. Alternatively, multiple battery cells can first be connected in series, in parallel, or in a mixed configuration to form battery module 6, and then multiple battery modules 6 can be connected in series, in parallel, or in a mixed configuration to form a whole assembly, which is then housed in housing 5.

[0080] Figure 3 for Figure 2 The diagram shows an exploded view of the battery module.

[0081] like Figure 3 As shown, in some embodiments, there are multiple battery cells 7, which are first connected in series, parallel, or mixed to form a battery module 6. The multiple battery modules 6 are then connected in series, parallel, or mixed to form a whole and housed in a casing.

[0082] Multiple battery cells 7 in battery module 6 can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 7 in battery module 6.

[0083] 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.

[0084] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0085] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0086] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0087] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0088] In some implementations, the electrode assembly is a stacked structure.

[0089] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0090] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0091] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0092] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0093] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0094] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0095] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0096] In some embodiments, the battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0097] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0098] In some embodiments, the housing includes an end cap and a housing, the housing having an opening, and the end cap covering the opening. The housing may have one or more openings. The end cap may also have one or more.

[0099] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0100] In some embodiments, a pressure relief mechanism is provided on the casing. The pressure relief mechanism is used to release the internal gas of the battery cell.

[0101] As an example, the internal pressure or temperature of a battery cell is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism is activated or a weak structure in the pressure relief mechanism is broken, thereby creating an opening or channel for the internal pressure or temperature to be released. The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0102] As an example, the pressure relief mechanism can be integrally molded with the housing.

[0103] As an example, the pressure relief mechanism can also be separately installed and connected to the housing.

[0104] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0105] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be configured as a through hole for venting gas inside the battery cell.

[0106] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0107] [Positive electrode plate]

[0108] In some embodiments, refer to Figure 4 The positive electrode 8 includes a positive current collector and a tab 81 extending from the positive current collector. An insulating coating 83 is disposed on the surface of the positive current collector near the tab 81. The insulating coating 83 includes an adhesive having a first structural unit containing a benzene ring and a second structural unit containing a polyolefin segment. The positive electrode 8 also includes a positive electrode film layer 82, which is disposed in a portion of the surface of the positive current collector. The insulating coating 83 is disposed between the positive electrode film layer 82 and the tab 81. The insulating coating 83 may cover a portion of the positive electrode film layer 82, or it may not cover the positive electrode film layer 82.

[0109] When manufacturing the electrodes for a battery cell, an insulating coating is typically applied to the surface of the current collector to reduce the risk of short circuits caused by contact between the positive and negative electrodes during use, which could lead to fires or explosions. In related technologies, the insulating coating often employs a combination of adhesive and insulating paint. The adhesive is usually a high-tensile-strength type, which can mitigate wrinkles and even breakage caused by rolling during electrode processing. However, the insulating coating prepared with this type of adhesive has low toughness and poor ductility, making it prone to breakage when subjected to impacts or bending during processing.

[0110] In this embodiment, by adjusting the design of the insulating coating, it can possess both high mechanical strength and good ductility, thereby reducing problems such as breakage during electrode processing. This reduces the risk of internal short circuits in the battery cell, thus improving the reliability of the battery cell. Specifically, the first structural unit containing benzene rings in the binder, as a rigid segment, acts as an anchor point and provides high mechanical strength, giving the insulating coating good tensile strength. The second structural unit containing polyolefin segments in the binder, as a flexible segment, provides good toughness, giving the insulating coating good ductility and flexibility. Through the cooperation of the first and second structural units in the binder, the insulating coating can possess both high mechanical strength and good flexibility, reducing problems such as breakage caused by rolling and bending during electrode processing. This reduces the risk of fire or explosion in the battery cell due to internal short circuits, thus improving the reliability of the battery cell.

[0111] In some embodiments, the molar content of the first structural unit in the adhesive molecule is 20% to 50%, and the molar content of the second structural unit is 50% to 80%.

[0112] Optionally, in the adhesive molecule, the molar content of the first structural unit is 25% to 45%, and the molar content of the second structural unit is 55% to 75%.

[0113] By limiting the molar content of the first and second structural units in the binder molecules to the above range, the mechanical strength and flexibility of the insulating coating can be further improved, and the risk of breakage during electrode processing can be reduced.

[0114] In some embodiments, the first structural unit may have the structural formula shown in equation (I):

[0115]

[0116] In formula (I),

[0117] R1 is selected from Or polymers formed from the above monomers;

[0118] X1 and X2 are each independently selected from -CONH- or -CO-.

[0119] In the first structural unit, the benzene ring in the R1 group can act as an anchoring group, giving the adhesive good adhesion. Simultaneously, the benzene ring structure provides high rigidity to the adhesive, resulting in a high mechanical strength for the manufactured insulating coating. Furthermore, the benzene ring structure in the first structural unit, as a polar group, can improve the solubility of the adhesive in organic solvents, thereby improving the dispersibility of the organic solvent in the insulating coating. This enhances the uniformity of dispersion of the components in the insulating coating, further improving its mechanical strength.

[0120] In some embodiments, the second structural unit may have a structural formula as shown in equation (II):

[0121]

[0122] In formula (II),

[0123] X3 and X4 are each independently selected from -O- or -NH-;

[0124] R2 has the structure shown in equation (II-1):

[0125]

[0126] In equation (II-1),

[0127] R3 is selected from phenyl or substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms;

[0128] Both m and n are integers, and 200≤m≤5000, 0≤n≤5000.

[0129] The polyolefin segments in the second structural unit provide the binder with good toughness and a certain strength, resulting in a well-ductile insulating coating. Simultaneously, the introduced branch (R3) in the second structural unit disrupts its crystallinity, further enhancing its strength and flexibility. The polyolefin segments in the second structural unit employ a double-bond-free saturated polyolefin structure, which improves the binder's oxidation resistance, thereby enhancing the oxidation resistance of the insulating coating and making it well-suited for use in positive electrode sheets.

[0130] In some embodiments, in the second structural unit, 0 ≤ n / m ≤ 5. The value of n / m represents the ratio of polyolefin segments at both ends of the second structural unit. By controlling the value of n / m within the above range, the second structural unit can provide good flexibility while also possessing a certain strength, which is beneficial for further improving the mechanical strength and ductility of the insulating coating.

[0131] In some embodiments, the adhesive may have a structural formula as shown in formula (III):

[0132]

[0133] In formula (III),

[0134] a, b, and c are all integers, and 0.2≤a / (a+b+c)≤0.5, 0.2≤b / (a+b+c)≤0.8, and 0≤c / (a+b+c)≤0.5.

[0135] The binder molecule with the structure shown in formula (III) has a combination of rigid and flexible segments. When applied to the insulating coating, it can make the insulating coating have both high polar strength and flexibility, thereby reducing the breakage problems caused by rolling, folding and other processes during the preparation of the electrode, thus improving the reliability of the battery cell.

[0136] In formula (III), a / (a+b+c), b / (a+b+c) and c / (a+b+c) represent the molar proportion of each chain segment in the adhesive molecule. By controlling the molar proportion of each chain segment within the above range, the adhesive can have a suitable proportion of rigid and flexible chain segments, which is beneficial to further improve the mechanical strength and flexibility of the insulating coating.

[0137] In some embodiments, the binder may be obtained by condensation polymerization of a first monomer and a second monomer, wherein...

[0138] The first monomer can be NCO-R1-NCO or COOH-R1-COOH.

[0139] R1 is selected from

[0140] The second monomer can be

[0141] R3 is selected from phenyl or substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms;

[0142] Both m and n are integers, and 200≤m≤5000, 0≤n≤5000.

[0143] The isocyanate or carboxyl groups at the end of the first monomer can undergo condensation polymerization with the hydroxyl or amino groups at the end of the second monomer to generate an adhesive with the structure shown in formula (III). The content of the first and second structural units in the resulting adhesive molecule can be adjusted by controlling the amounts of the first and second monomers. During the condensation polymerization process, the polyolefin segments in the second structural unit can be further polymerized, resulting in a higher polymer content in the flexible segments.

[0144] In some embodiments, the molar ratio of the first monomer to the second monomer can be 1:(1-4).

[0145] By controlling the molar ratio of the first monomer and the second monomer within the above range during the condensation polymerization reaction, the resulting binder molecules can have a suitable ratio of rigid and flexible segments, which is beneficial to further improve the mechanical strength and ductility of the insulating coating.

[0146] In some embodiments, the weight-average molecular weight of the adhesive can be from 300,000 to 1,500,000. Exemplarily, the weight-average molecular weight of the adhesive can be 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 50,000, 1,000,000, 110,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, or any range of the above values. The weight-average molecular weight of the adhesive can be selected from 400,000 to 1,450,000, and more preferably from 500,000 to 1,400,000.

[0147] Molecular weight has a well-known meaning in the art and can be determined using instruments and methods well-known in the art. For example, gel permeation chromatography can be used, referring to the GB / T21863-2008 standard. Specifically, it can be obtained by testing with an ultra-high performance polymer chromatograph: ACQUITY APC; detector: ACQUITY differential refractive index detector. The test steps are as follows: (1) Preheating: Install the chromatographic column and tubing, turn on the control panel, test the power supply, etc., and open the test software Empower; (2) Parameter settings: Injection volume: 0 μL to 50 μL (depending on the sample concentration); Pump flow rate: 0.2 mL / min; Mobile phase: 30 mol / L LiBr NMP solution; Sealing cleaning solution: isopropanol; Pre-column: PLgel10um MiniMIX-B Guard (size: 50 mm × 4.6 mm × 2); Analytical phase: PLgel10um MiniMIX-B (size: 250 mm × 4.6 mm); Standard: Polystyrene sleeve; Run time: 30 min; Detector: ACQUITY differential refractive index (RI) detector; Column oven temperature: 90℃; Detector temperature: 55℃. (3) Sample testing: a. Preparation of standard and test samples: Weigh 0.002g to 0.004g of standard / test sample and add 2mL of mobile phase liquid to prepare a 0.1% to 0.5% mixed standard and place it in the refrigerator for >8h; b. Standard / sample testing: Edit the sample group to be tested, select the established sample group method, and after the baseline stabilizes, click the run queue to start testing the sample; (4) Data processing: Based on the relationship between retention time and molecular weight, establish a calibration curve using a chemical workstation, perform integral quantification on the sample spectrum, and the chemical workstation automatically generates molecular weight and molecular weight distribution results.

[0148] In some embodiments, the adhesive content in the insulating coating can be from 20% to 80% by mass. Exemplarily, the adhesive content in the insulating coating can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 68%, 70%, 75%, 80%, or any range of the foregoing values. Optionally, the adhesive content in the insulating coating can be from 25% to 75%, more preferably from 30% to 70%.

[0149] The binder plays a role in bonding the insulating coating with the current collector to form a film. By controlling the binder content in the insulating coating within the above-mentioned range, the insulating coating can be endowed with high strength, high ductility, and high toughness. At the same time, the amount of binder within the above-mentioned range can make the insulating coating have better structural stability, reduce the risk of coating peeling off during the charge and discharge cycle of the battery cell, and further improve the cycle performance and reliability of the battery cell.

[0150] In some embodiments, the insulating coating may further comprise insulating powder, and the mass percentage of the insulating powder in the insulating coating may be from 20% to 80%. Exemplarily, the mass percentage of the insulating powder in the insulating coating may be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 68%, 70%, 75%, 80%, or any range of the above values.

[0151] Optionally, the percentage content of the adhesive in the insulating coating can be 25% to 75%, and more preferably 30% to 70%.

[0152] Insulating powder plays an insulating role in insulating coatings, enhancing their insulation properties and reducing the risk of short circuits caused by contact between the positive and negative electrodes in a single battery cell. Furthermore, the addition of insulating powder can further improve the strength of the insulating coating, giving it higher mechanical strength properties. This helps reduce the risk of coating wrinkles and cracks caused by rolling during electrode fabrication, thus improving the reliability of the battery cell.

[0153] In some embodiments, the insulating powder may include one or more of metal oxides, metal hydroxides, and inorganic silicates.

[0154] Optionally, the insulating powder may include one or more of alumina, boehmite, magnesium oxide, magnesium hydroxide, mica powder, talc powder, hydrotalcite, and montmorillonite.

[0155] In some embodiments, the volume distribution particle size Dv50 of the insulating powder can be from 0.8 μm to 5 μm, optionally from 1 to 4, and more preferably from 1.5 μm to 3 μm.

[0156] When the volume distribution particle size of the insulating powder is within the above range, it can be uniformly dispersed in the insulating slurry, which is beneficial to obtaining an insulating coating with uniform thickness and stable structure.

[0157] In some embodiments, the thickness of one side of the insulating coating can be from 10 μm to 50 μm. Exemplarily, the thickness of one side of the insulating coating can be 10 μm, 15 μm, 20 μm, 25 μm, 0 μm, 35 μm, 40 μm, 45 μm, 50 μm, or any range of the above values. Optionally, the thickness of one side of the insulating coating can be from 15 μm to 45 μm, and more preferably from 18 μm to 40 μm.

[0158] Controlling the thickness of the insulating coating on one side within the aforementioned range ensures that the insulating coating possesses good mechanical strength, toughness, and insulation properties. A thinner single-sided insulating coating results in poor insulation and lower mechanical strength, making it prone to cracking and short circuits. Conversely, a thicker single-sided insulating coating leads to reduced ductility and can affect the overall thickness of the electrode, resulting in a decrease in the proportion of active material in the battery cell, which in turn affects the battery cell's capacity and cycle performance.

[0159] In some embodiments, the tensile strength of the insulating coating can be from 40 MPa to 80 MPa, optionally from 45 MPa to 75 MPa, and more preferably from 50 MPa to 70 MPa.

[0160] The tensile strength of the insulating coating is within the above range, which has good mechanical strength. It can reduce the problems of wrinkles and breakage caused by rolling and other processes during the preparation of the positive electrode sheet, and improve the reliability of the battery cell.

[0161] In some embodiments, the elongation at break of the insulating coating may be 50% to 105%; optionally 60% to 105%, and more preferably 70% to 105%.

[0162] When the elongation at break of the insulating coating is within the above range, the coating has good toughness and ductility, which can reduce the risk of breakage due to bending and collision during the preparation of the positive electrode sheet, and is beneficial to the reliability of the battery cell.

[0163] Tensile strength and elongation at break have well-known meanings in the art and can be determined using instruments and methods well-known in the art. For example, an insulating slurry containing binder and insulating powder can be coated onto release paper, dried thoroughly in an oven at 110°C, with the thickness of the insulating coating controlled at 60 μm after drying. Then, strips of 10 cm × 2.5 cm can be cut and tested for tensile strength and elongation at break using the instruments and methods specified in GB / T 1040.1-2018 "Tension Methods for Plastics".

[0164] In some embodiments, the peel strength of the insulating coating can be from 50 N / m to 70 N / m; optionally from 55 N / m to 68 N / m.

[0165] The peel strength of the insulating coating is within the above range, indicating good adhesion properties and high adhesion strength with the current collector. This can reduce the risk of the insulating coating falling off during battery cell cycling, which is beneficial to improving the reliability and cycle performance of the battery cell.

[0166] Peel strength is a term known in the art and can be measured using instruments and methods known in the art. For example, an insulating paste containing binder and insulating powder can be scraped onto aluminum foil, dried thoroughly in an oven at 110°C, with the thickness of the insulating coating controlled at 30 μm after drying. Then, a strip sample of 10 cm × 2.5 cm can be cut, pasted onto a stainless steel plate, and the peel strength can be tested using instruments and methods specified in GB / T 2790 "Coating Peel Test Method".

[0167] In some embodiments, the swelling rate of the insulating coating in phthalate solvents can be 10% to 50%, optionally 15% to 40%, and more preferably 18% to 30%.

[0168] In this application, the swelling rate of the insulating coating refers to the liquid absorption of the insulating coating before and after immersion in the solvent, which reflects the liquid absorption and retention capacity of the insulating coating. When the swelling rate of the insulating coating is within the above-mentioned range, it has good liquid absorption and retention performance, and can store more electrolyte during the charge-discharge cycle of the battery cell, which is beneficial to improving the cycle performance of the battery cell.

[0169] The swelling rate of the insulating coating can be determined by the following method: An insulating slurry containing binder and insulating powder is scraped onto aluminum foil and dried thoroughly in a 110℃ oven. The thickness of the insulating coating after drying is controlled to be 30μm. A 5cm×5cm sample is cut and weighed, recorded as m0. The sample is then immersed in a carbonate solvent (the organic solvent of the electrolyte can be dimethyl carbonate) and stored at 60℃ for 7 days. After removal, the residual electrolyte on the sample surface is quickly wiped off, and the sample is weighed and recorded as m1. The swelling rate is calculated as follows: Swelling rate (%) = (m1-m0) / m0×100%.

[0170] In some embodiments, the positive electrode sheet includes a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0171] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium, thereby obtaining a negative electrode-free lithium metal battery cell.

[0172] As examples, positive electrode active materials may include, but are not limited to, one or more of lithium transition metal oxides, metal chalcogenides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, lithium titanium oxides, and their respective modified compounds. Lithium transition metal oxides may include, but are not limited to, layered structures and spinel structures. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, lithium iron manganese phosphate and carbon composites, and their respective modified compounds.

[0173] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e D f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M may include, but is not limited to, one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D may include, but is not limited to, one or more of N, F, S and Cl.

[0174] In some embodiments, the positive electrode active material may simultaneously comprise lithium transition metal oxide and lithium phosphate. This is advantageous for obtaining battery cells that balance high capacity and high reliability.

[0175] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, and LiNi 1 / 2 Mn 1 / 2O2, LiMn2O4, Li 4 / 3 Ti 5 / 3 O4, LiNi 1 / 2 Mn 1 / 2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, Li 1.13 Ti 0.57 Fe 0.3 One or more of S2.

[0176] In some embodiments, the positive electrode active material includes a material capable of both sodium extraction and insertion. This results in a sodium-free negative electrode battery cell. For example, the positive electrode active material may include, but is not limited to, one or more of layered transition metal oxides (including, but not limited to, P2-type, O3-type, etc.), polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian materials.

[0177] In some embodiments, as an example, the positive electrode active material may include, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na 0.67 MO2 (M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, and Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, and Mo), NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and one or more of their respective modified compounds.

[0178] 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.

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

[0180] In some embodiments, the positive electrode 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 the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0181] 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 first layer of polymeric material and a layer of metallic material formed on at least one surface of the first layer of polymeric material. As an example, the metallic 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 first layer of polymeric material may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0182] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0183] In some embodiments, the positive electrode sheet can be prepared by the following method:

[0184] Positive current collector, positive slurry, and insulating slurry containing binder and insulating powder are provided respectively;

[0185] The positive electrode slurry and the insulating slurry are coated onto the positive electrode current collector, such that the insulating slurry coating area is located on one or both sides of the positive electrode slurry coating area;

[0186] After drying, the material is cold-pressed, slit, and fitted with tabs to obtain the positive electrode sheet.

[0187] In some embodiments, the insulating paste includes a solvent, which may include N-methylpyrrolidone (NMP).

[0188] In some embodiments, the solid content of the insulating grout can be from 20% to 40%. Exemplarily, the solid content of the insulating grout can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, or any range of the above values. Optionally, the solid content of the insulating grout can be from 25% to 35%.

[0189] In this embodiment, the solid content of the insulating slurry refers to the ratio of the sum of the masses of the binder and the insulating powder in the insulating slurry to the total mass of the insulating slurry. Controlling the solid content of the insulating slurry within the above-mentioned range is beneficial for forming an insulating coating with uniform thickness and stable structure.

[0190] In some embodiments, the viscosity of the insulating slurry can be from 1000 mPa·s to 8000 mPa·s. Exemplarily, the viscosity of the insulating slurry can be 1000 mPa·s, 1500 mPa·s, 2000 mPa·s, 2500 mPa·s, 3000 mPa·s, 3500 mPa·s, 4000 mPa·s, 4500 mPa·s, 5000 mPa·s, 5500 mPa·s, 6000 mPa·s, 6500 mPa·s, 7000 mPa·s, 7500 mPa·s, 8000 mPa·s, or any range of the above values. Optionally, the viscosity of the insulating slurry can be from 1800 mPa·s to 7000 mPa·s.

[0191] When the viscosity of the insulating slurry is within the above range, it is beneficial to obtain an insulating coating with stable structure and thick insulation.

[0192] [Negative electrode plate]

[0193] In some embodiments, 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, wherein the metal element in the first metal layer may include one or more of alkali metal elements and alkaline earth metal elements.

[0194] In some embodiments, the metallic material in the first metal layer may include one or more of elemental lithium, lithium alloy, sodium, and sodium alloy.

[0195] Lithium alloys can be alloys formed from metallic lithium with other metallic or non-metallic elements. For example, other metallic elements in lithium alloys may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements may include one or more of boron, carbon, and silicon.

[0196] Sodium alloys can be alloys formed from metallic sodium with other metallic or non-metallic elements. For example, other metallic elements in a sodium alloy may include one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements may include one or more of boron, carbon, and silicon.

[0197] In some embodiments, the negative electrode sheet may include a negative current collector and exclude the first metal layer to assemble a negative electrode-free metal battery cell.

[0198] In some embodiments, the negative electrode current collector may include a metal foil, a three-dimensional porous current collector, or a composite current collector. Examples of metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of three-dimensional porous current collectors include copper mesh, nickel mesh, aluminum mesh, copper foam, nickel foam, and aluminum foam. The composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. Examples of metal materials include, but are not limited to, one or more of copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Examples of polymer material substrates include, but are not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0199] [Isolation Component]

[0200] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0201] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0202] 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.

[0203] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0204] [Electrolytes]

[0205] In some embodiments, the battery cell further includes an electrolyte. The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte, which can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0206] Liquid electrolytes include electrolyte salts and organic solvents.

[0207] In some embodiments, the electrolyte salt includes anions, which may include bis(fluorosulfonyl)imide anion (FSI-), bis(trifluoromethanesulfonyl)imide anion (TFSI-), bis(oxalatoborate) anion (BOB-), bis(fluorooxalatoborate) anion (DFOB-), and bis(fluorodioxalato)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.

[0208] In some embodiments, the electrolyte salt includes a cation, which may include one or more of lithium ions and sodium ions.

[0209] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0210] In some embodiments, the concentration of the electrolyte salt may be 0.3 mol / L or higher, optionally 0.7 mol / L or higher, and further optionally 4 mol / L or lower, optionally 2.5 mol / L or lower, or 1.7 mol / L or lower. When the concentration of the electrolyte salt is within the above range, the electrolyte can have a suitable ionic conductivity.

[0211] Organic solvents may include, but are not limited to, one or more of esters, ethers, sulfones, and nitriles. Esters may include, but are not limited to, one or more of carbonates, phosphate esters, carboxylic esters, sulfate esters, and sulfonates. Carbonates may include cyclic carbonates and / or chain carbonates; optionally, carbonates may include both cyclic and chain carbonates. Chain carbonates may include low-viscosity polar chain carbonates, aliphatic branched carbonates, etc.

[0212] 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.

[0213] In some embodiments, the electrolyte may optionally include additives. For example, the 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.

[0214] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0215] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0216] 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.

[0217] 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.

[0218] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0219] 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 package, dried, and then injected with the electrolyte. After vacuum sealing, settling, and formation processes, a battery cell is obtained. Multiple battery cells can be further connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0220] Example

[0221] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0222] Example 1

[0223] Preparation of insulating paste

[0224] S10, take 100g of binder and 667g of solvent N-methylpyrrolidone and mix them. Stir and disperse at a linear speed of 25m / s for 120min. During this period, turn on the circulating cooling water to control the dispersion temperature to be maintained at 20℃-40℃.

[0225] Add 233g of boehmite powder (Dv50 is 2μm) to S20, maintain a dispersion linear velocity of 25m / s and a dispersion temperature of 20℃-40℃, and continue dispersion for 60min; after dispersion, filter through a 150-mesh screen to obtain the insulating slurry; the structural formula of the binder is as follows:

[0226] in,

[0227] a / (a+b+c)=0.4, b / (a+b+c)=0.2, c / (a+b+c)=0.4; the weight-average molecular weight of the adhesive is 500,000.

[0228] Positive electrode sheet

[0229] Polyvinylidene fluoride (PVDF), lithium iron phosphate as the positive electrode active material, conductive carbon black as the conductive agent, and N-methylpyrrolidone (NMP) as the solvent are mixed and stirred evenly in a mass ratio of 1.28:62.2:0.52:36 to obtain the positive electrode slurry.

[0230] The positive electrode slurry and the insulating slurry are uniformly coated on the positive electrode current collector aluminum foil, and the insulating slurry is coated on both sides of the positive electrode slurry. After drying at 110℃, the positive electrode sheet is obtained by cold pressing, slitting, and laser forming of the electrode tabs. The single-sided thickness of the insulating coating is 30μm.

[0231] Negative electrode sheet

[0232] The negative electrode material, artificial graphite, conductive agent, carbon black, binder, styrene-butadiene rubber (SBR), and thickener, sodium carboxymethyl cellulose (CMC-Na), are dissolved in deionized water at a weight ratio of 96.2:0.8:0.8:1.2 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is uniformly coated onto the negative electrode current collector copper foil once or multiple times, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0233] Separating membrane

[0234] Polypropylene film was selected as the separator.

[0235] electrolyte

[0236] In an argon-atmospheric glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly at a volume ratio of 3 / 7. LiPF6 lithium salt was then added and dissolved in the organic solvent to prepare a solution. The mixture was stirred until homogeneous to obtain the electrolyte. The LiPF6 concentration was 1 mol / L.

[0237] battery cell

[0238] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The cells are then wound to obtain a bare cell. Tabs are welded onto the bare cell, and the cell is placed in an aluminum casing. It is then baked at 80°C to remove moisture, followed by the injection of electrolyte and sealing. The cell undergoes a series of processes including settling, hot and cold pressing, formation, shaping, and capacity testing to produce a single battery cell.

[0239] Examples 2 to 10

[0240] The difference from Example 1 is that the parameters of the first structural unit and / or the second structural unit in the adhesive structure are different, as detailed in Table 1.

[0241] Comparative Example 1

[0242] The difference from Example 1 is that the adhesive is polyvinylidene fluoride (PVDF).

[0243] Table 1

[0244]

[0245]

[0246] Examples 12-21

[0247] The structural formula of the adhesive is the same as that in Example 1. The difference is that the weight-average molecular weight and / or the content of each structural unit of the adhesive are different, as detailed in Table 2.

[0248] Comparative Examples 2-3

[0249] The difference from Example 1 is that the structure of the adhesive is different, as detailed in Table 2.

[0250] Table 2

[0251]

[0252]

[0253] Examples 22-29

[0254] The difference from Example 1 is that the parameters of the insulating coating are different, as detailed in Table 3.

[0255] Table 3

[0256]

[0257] Performance testing

[0258] 1. Viscosity test of insulating grout

[0259] Take 500 mL of insulating slurry, filter it through a 150-mesh filter, and test its rotational viscosity according to GB / T 2794-2013 "Determination of Viscosity of Adhesives - Single-Cylinder Rotation Viscometer Method".

[0260] 2. Tensile strength and elongation at break of the insulating coating

[0261] The insulating slurry is scraped onto the release paper and placed in an oven at 110℃ to dry thoroughly. The thickness of the insulating coating after drying is controlled to be 60μm. Then, a strip sample of 10cm×2.5cm is cut out and the tensile strength and elongation at break are tested according to the instruments and methods specified in GB / T1040.1-2018 "Tension Methods for Plastics".

[0262] 3. Peel strength of the insulating coating

[0263] The insulating slurry was scraped onto the aluminum foil and dried thoroughly in an oven at 110℃. The thickness of the insulating coating after drying was controlled to be 30μm. Then, a strip sample of 10cm×2.5cm was cut and pasted onto a stainless steel plate. The peel strength was tested according to the instruments and methods specified in GB / T 2790 "Coating Peel Test Method".

[0264] 4. Swelling rate of insulating coating

[0265] An insulating slurry containing binder and insulating powder was scraped onto aluminum foil and dried thoroughly in a 110℃ oven. The thickness of the insulating coating after drying was controlled to be 30μm. A 5cm×5cm sample was cut and weighed, recorded as m0. The sample was then immersed in dimethyl carbonate and stored at 60℃ for 7 days. After removal, the residual electrolyte on the sample surface was quickly wiped off and weighed, recorded as m1. The swelling rate was calculated as follows: Swelling rate (%) = (m1-m0) / m0×100%.

[0266] 5. Battery cell 60℃ cycle performance test

[0267] The battery cells were charged at 1C to 3.65V under a constant temperature environment of 60℃ and a voltage range of 2.5~3.65V. Then, they were charged at a constant voltage of 3.65V until the current ≤0.05mA, allowed to stand for 5 minutes, and then discharged at 1C to 2.5V. The capacity was recorded as Dn (n=0, 1, 2, …). This process was repeated for 500 cycles, and the capacity retention rate was measured. After 500 cycles, the cells were disassembled to check for any delamination of the insulating coating.

[0268] 6. Battery cell 30-day storage capacity retention rate

[0269] The battery cells were charged at 1C to 3.65V, then charged at 3.65V under constant voltage until the current was ≤0.05mA. After standing for 5 minutes, they were discharged at 1C to 2.5V, and the discharge capacity was recorded as D0. Subsequently, the cells were charged at 1C to 3.65V and stored at 60℃ for 30 days, and the capacity retention rate was measured.

[0270] The performance test results are detailed in Table 4.

[0271] Table 4

[0272]

[0273]

[0274] As can be seen from Examples 1 to 10 and Comparative Example 1, the insulating coating prepared by the binder with the first structural unit and the second structural unit provided in this application has good mechanical strength and toughness. Its tensile strength and elongation at break are significantly improved compared with PVDF. When applied to battery cells, it can improve the storage stability and cycle performance of battery cells.

[0275] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell comprising a positive electrode sheet, characterized by, The positive electrode tab includes: a positive electrode current collector, and a tab extending from the positive electrode current collector; an insulating coating layer on a surface of the positive electrode current collector near the tab, the insulating coating layer comprising a binder; wherein the binder has a first structural unit containing a benzene ring and a second structural unit containing a polyolefin chain segment.

2. The battery cell of claim 1, wherein, In the binder, the molar content of the first structural unit is 20% to 50%, and the molar content of the second structural unit is 50% to 80%.

3. The battery cell according to claim 1 or 2, characterized in that, The first structural unit has a structural formula as shown in formula (I): In formula (I), R1is selected from or a multimer of the above monomers; X1 and X2 are each independently selected from -CONH- or -CO-.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The second structural unit has a structural formula as shown in formula (II): In formula (II), X3 and X4 are each independently selected from -O- or -NH-; R2 has a structure as shown in formula (II-1): In formula (II-1), R3 is selected from a phenyl group or a substituted or unsubstituted alkyl group with a carbon atom number of 1 to 6; m and n are each an integer, and 200≤m≤5000, 0≤n≤5000.

5. The battery cell of claim 4, wherein, 0≤n / m≤5.

6. The battery cell of any one of claims 1 to 5, wherein, The binder has a structural formula as shown in formula (III): In formula (III), R1is selected from or a multimer of the above monomers; R3 is selected from a phenyl group or a substituted or unsubstituted alkyl group with a carbon atom number of 1 to 6; X1 and X2 are each independently selected from -CONH- or -CO-. X3 and X4 are each independently selected from -O- or -NH-; a, b, and c are each an integer, and 0.2≤a / (a+b+c)≤0.5, 0.2≤b / (a+b+c)≤0.8, 0≤c / (a+b+c)≤0.

5.

7. The battery cell of any one of claims 1 to 6, wherein, The weight average molecular weight of the binder is 300,000 to 1,500,000.

8. The battery cell of any one of claims 1 to 7, wherein, The mass percentage content of the binder in the insulating coating layer is 20% to 80%.

9. The battery cell of any one of claims 1 to 8, wherein, The insulating coating layer further includes an insulating powder, the insulating powder including one or more of a metal oxide, a metal hydroxide, and an inorganic silicate, and the mass percentage content of the insulating powder in the insulating coating layer is 20% to 80%.

10. The battery cell of any one of claims 1 to 9, wherein, The insulating coating layer satisfies at least one of the following conditions: (1) the single-sided thickness of the insulating coating layer is 10 μm to 50 μm; (2) the tensile strength of the insulating coating layer is 40 MPa to 80 MPa; (3) the elongation at break of the insulating coating layer is 50% to 105%; (4) the peel strength of the insulating coating layer is 50 N / m to 70 N / m; (5) the swelling rate of the insulating coating layer in a carbonate-based solvent is 10% to 50%.

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