Battery monomer, battery device and power utilization device

Abstract

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode pole piece, the electrode pole piece comprises a current collector, the current collector has an upper surface and a lower surface corresponding to the upper surface, and at least one of the upper surface and the lower surface is provided with an electrode material layer; in the direction perpendicular to the upper surface, the electrode pole piece is provided with a side tangent plane, and the side tangent plane comprises a current collector side tangent plane and an electrode material layer side tangent plane; the side section is provided with an adhesive layer, and the adhesive layer at least covers the side section of the current collector; the adhesive layer is obtained by polymerizing raw materials including acrylic resin, an active monomer and a free radical polymerization initiator; the active monomer comprises acrylic ester or an acrylic ester derivative. By arranging the adhesive layer, burrs on the side section of the pole piece can be coated, so that adverse effects caused by the burrs are reduced, and the safety performance of the battery 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] Rechargeable batteries have seen widespread development. During the electrode cutting process, fine burrs and wires can occur at the edges of the electrodes. These burrs and wires pose significant safety hazards, potentially causing localized short circuits, self-discharge, and reduced battery cycle life and yield. Larger burrs can even puncture the separator, leading to short circuits between the positive and negative electrodes, and in severe cases, thermal runaway and spontaneous combustion, posing a serious safety risk. Summary of the Invention

[0003] The purpose of this application is to provide a battery cell, a battery device, and an electrical device, wherein the side cut surface of the electrode sheet of the battery cell is provided with an adhesive layer, which serves to cover the burrs on the cut surface, thereby improving the safety performance of the battery.

[0004] Therefore, a first aspect of this application provides a battery cell including an electrode sheet, the electrode sheet including a current collector having an upper surface and a corresponding lower surface; at least one of the upper surface and the lower surface is provided with an electrode material layer;

[0005] Along a direction perpendicular to the upper surface, the electrode sheet has a side section, which includes a current collector side section and an electrode material layer side section;

[0006] The side section is provided with an adhesive layer, which at least covers the side section of the current collector; the adhesive layer is obtained by polymerization of raw materials including acrylic resin, active monomer and free radical polymerization initiator; the active monomer includes acrylate or acrylate derivative.

[0007] The electrode sheet has a narrow side section, and the aforementioned raw material has good processing properties, making it suitable for precise application to this narrow side section. Furthermore, after polymerization, it provides good adhesion and coating. By applying the aforementioned adhesive layer to at least one side section of the electrode sheet, burrs on the current collector side section can be coated, thereby reducing the adverse effects of burrs and improving battery safety performance.

[0008] In some embodiments, the width of the adhesive layer is 10–50 μm in a direction perpendicular to the upper surface.

[0009] By using the above-mentioned adhesive layer width, not only can the burrs on the side cut surface of the electrode be better covered, but the adhesive layer is also less likely to break or fall off when the electrode is wound or folded.

[0010] In some embodiments, the viscosity of the raw material at 50°C is ≤50 cps.

[0011] The electrode sheet has an extremely narrow cross-section, which requires the raw material applied to the cross-section surface to have excellent processing properties to better match high-precision equipment such as electrohydraulic inkjet printers. When the viscosity of the raw material meets the above conditions, it is beneficial to match high-precision equipment and achieve precise control.

[0012] In some embodiments, the raw materials include, by weight, 10-30 parts of acrylic resin, 40-80 parts of active monomer, and 2-10 parts of free radical polymerization initiator.

[0013] When the above weight ratio is used, the processing performance of the raw material and the adhesion of the adhesive layer are relatively balanced, which is suitable for forming an adhesive layer on the side cut surface of the electrode sheet.

[0014] In some embodiments, the free radical polymerization initiator includes a photoinitiator.

[0015] When a photoinitiator is used, online instant curing can be achieved, improving the processing efficiency of applying the adhesive layer. In particular, when using the aforementioned raw materials with a viscosity ≤50cps at 50°C, and in conjunction with a photoinitiator, it is possible to achieve wired communication between the adhesive layer application equipment (such as an electrohydraulic inkjet printer) and the electrode sheet cutting equipment, without affecting the processing efficiency.

[0016] In some embodiments, the active monomer includes a first monomer, wherein the first monomer is a monofunctional monomer; and / or,

[0017] The first monomer comprises at least one selected from the group consisting of isoborneol acrylate, tetrahydrofuran acrylate, bisphenol α-dimethacrylate, propylene ester-2-ethylethyl acrylate, β-hydroxyethyl methacrylate, lauryl methacrylate, and 2-methaneoxyethyl acrylate.

[0018] By applying the first monomer mentioned above, the toughness of the adhesive layer is improved, so that the adhesive layer is not easy to break or fall off when the electrode is wound or folded.

[0019] In some embodiments, the active monomer includes a second monomer, the second monomer having a functionality greater than or equal to 2; and / or,

[0020] The second monomer includes at least one selected from the group consisting of: tripropylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, dimethylolethane triacrylate, trimethylolpropane triacrylate, 3-ethoxytrimethylolpropane triacrylate, pentaerythritol pentaacrylate, and dipentaerythritol pentaacrylate.

[0021] By applying a second monomer, the degree of crosslinking of the raw material during curing can be increased, which is beneficial to improving the mechanical strength of the adhesive layer.

[0022] In some embodiments, the mass ratio of the first monomer to the second monomer is 10:7 to 20.

[0023] When the first monomer and the second monomer are within the above-mentioned mass ratio range, it is beneficial to make the adhesive layer have both high mechanical properties and good toughness.

[0024] In some embodiments, the active monomer comprises a hydrophobic monomer, wherein the hydrophobic monomer has a contact angle with water ≥90°; and / or,

[0025] The hydrophobic monomer includes at least one selected from the group consisting of trifluoroethyl methacrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl methacrylate, tetrafluoropropanol methacrylate, and trimethylsilane methacrylate.

[0026] By applying hydrophobic monomers, it is beneficial to improve the resistance of the adhesive layer to humid heat aging and water resistance, thereby improving the stability of the battery cell during long-term storage or use.

[0027] In some embodiments, the hydrophobic monomer accounts for 2% to 10% of the mass of the active monomer.

[0028] In some embodiments, the raw material further includes a coupling agent, the coupling agent including a silane coupling agent; and / or,

[0029] The coupling agent comprises at least one selected from the group consisting of: 3-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, α-methacryloyloxymethyltrimethylsilane and γ-methacryloyloxypropyltrimethoxysilane.

[0030] By adding the above-mentioned coupling agent, the adhesion of the adhesive layer can be further improved.

[0031] A second aspect of this application provides a method for preparing a battery cell, comprising providing a battery cell to be coated with an adhesive layer, the battery cell including an electrode sheet, the electrode sheet including a current collector, the current collector having an upper surface and a corresponding lower surface; at least one of the upper surface and the lower surface being provided with an electrode material layer; the electrode sheet having a side section along a direction perpendicular to the upper surface, the side section including a current collector side section and an electrode material layer side section;

[0032] Raw materials including acrylic resin, active monomer and free radical polymerization initiator are provided. The raw materials are placed on the side section of the electrode sheet by inkjet printing. Suitable conditions are provided for the free radical polymerization initiator to initiate polymerization, thereby forming an adhesive layer on the side section of the electrode sheet. The adhesive layer at least covers the side section of the current collector.

[0033] In some embodiments, the inkjet printing device includes a thermoelectric inkjet printer.

[0034] Electrohydraulic inkjet printers have high precision. The nozzle width of an electrohydraulic inkjet printer can be as small as 1 μm. By adjusting the nozzle width of the electrohydraulic inkjet printer to be greater than the width of the current collector's side section and less than the width of the electrode's side section, it is relatively easy to ensure that the adhesive layer at least covers the current collector's side section and does not exceed the electrode's side section.

[0035] A third aspect of this application provides a battery device comprising the battery cell described in the first aspect of this application or a battery cell prepared according to the preparation method described in the second aspect of this application.

[0036] A fourth aspect of this application provides an electrical device comprising a battery cell as described in the first aspect of this application, a battery cell prepared according to the preparation method described in the second aspect of this application, or a battery device as described in the third aspect of this application.

[0037] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more obvious and understandable, the specific implementation methods of this application are listed below. Attached Figure Description

[0038] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. In the drawings:

[0039] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0040] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0041] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application;

[0042] Figure 4This is a schematic diagram of a battery pack according to one embodiment of this application;

[0043] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of this application is shown;

[0044] Figure 6 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to an embodiment of this application;

[0045] Figure 7 This is a photograph of a side cross-section of a battery electrode sheet according to an embodiment of this application;

[0046] Explanation of reference numerals in the attached figures:

[0047] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Casing; 52 Electrode assembly; 53 End cap. Detailed Implementation

[0048] Exemplary embodiments of this disclosure will now be described in more detail. It should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0049] 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 a specific parameter, it is expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0051] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0052] Unless otherwise specified, all steps of 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.

[0053] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0054] Rechargeable batteries have seen widespread development. During the electrode cutting process, fine burrs and wires can occur at the edges of the electrodes. These burrs and wires pose significant safety hazards, potentially causing localized short circuits, self-discharge, and reduced battery cycle life and yield. Larger burrs may even puncture the separator, leading to a short circuit between the positive and negative electrodes, also posing a safety risk.

[0055] To address the aforementioned issues, existing technologies offer the following solutions: Mechanical friction is used to remove burrs; however, this method suffers from low efficiency and the risk of roller wear leading to unsatisfactory processing results. Methods involving the corrosion of burrs with acid or alkali solutions are also problematic, as they easily introduce impurities and make it difficult to ensure consistent reaction depth across batches of electrodes. A common approach is to apply an adhesive layer; however, due to the extremely narrow thickness of the electrode's side surface, existing adhesive layers are difficult to apply precisely to the side surface, easily overflowing onto at least part of the upper / lower surface of the electrode. This leads to new technical problems such as reduced battery energy density. The main reason for this is the poor processing performance of the raw materials used to form the adhesive layer (e.g., polyurethane), which can only be applied through coating (e.g., spraying) or dipping.

[0056] This application proposes to provide an adhesive layer on the side cut surface of the electrode, thereby improving the safety issues caused by the burrs by covering them with the adhesive layer. The technical solution provided in the embodiments of this application not only overcomes the defects of the aforementioned mechanical friction method and chemical corrosion method; but also overcomes the problem of the inability to accurately set the adhesive layer in the prior art by improving the raw materials, thus avoiding the negative effects caused by adhesive layer overflow.

[0057] The solutions described in the embodiments of this application are applicable to battery cells, battery devices using the battery cells, and electrical devices using the battery cells or battery devices.

[0058] battery cell

[0059] 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.

[0060] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0061] [Electrode Assembly]

[0062] A single battery cell typically includes an electrode assembly. The electrode assembly includes electrode plates and a separator. The electrode plates include a positive electrode and a negative electrode, and the separator is located between the negative and positive electrode plates. During the charging and discharging process of a single battery cell, active ions (such as lithium ions or sodium ions) repeatedly insert and extract between the positive and negative electrode plates. The separator, located between the positive and negative electrode plates, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0063] In some embodiments of this application, the electrode sheet includes a current collector having an upper surface and a corresponding lower surface; at least one of the upper surface and the lower surface is provided with an electrode material layer;

[0064] Along a direction perpendicular to the upper surface, the electrode sheet has a side section, which includes a current collector side section and an electrode material layer side section;

[0065] The side section is provided with an adhesive layer, which at least covers the side section of the current collector; the adhesive layer is obtained by polymerization of raw materials including acrylic resin, active monomer and free radical polymerization initiator; the active monomer includes acrylate or acrylate derivative.

[0066] The narrow side facets of electrodes present a significant challenge in achieving precise control over adhesive layer application to mitigate burrs. Existing adhesive materials suffer from insufficient processing properties, limiting application to coating (e.g., spraying) or dipping methods. This inevitably leads to adhesive overflow, covering at least a portion of the electrode's upper / lower surface, negatively impacting energy density. The material described in this application possesses excellent processing properties, suitable for precise application to the narrow side facets, and readily polymerizes and cures rapidly on the side facets, providing good adhesion and coating after polymerization. By applying this adhesive layer to at least one side facet of the electrode, burrs can be effectively covered, reducing their adverse effects and improving battery safety.

[0067] In some embodiments, the adhesive layer is disposed on the side cross-section of the positive electrode of the battery cell; the adhesive layer covers the side cross-section of the positive current collector. In some embodiments, the adhesive layer is disposed on the side cross-section of the negative electrode of the battery cell; the adhesive layer covers the side cross-section of the negative current collector. In some embodiments, the adhesive layer is disposed on the side cross-sections of both the positive and negative electrode plates of the battery cell.

[0068] In some embodiments, the side cut surface of the electrode sheet is provided with an adhesive layer, and the upper and lower surfaces of the electrode material layer do not have the adhesive layer. That is, the adhesive layer is precisely disposed on the side cut surface, and not on the upper and lower surfaces of the electrode material layer.

[0069] Please refer to Figure 7 , Figure 7 This is a side-section photograph of an electrode sheet prepared according to one embodiment of this application. Figure 7 (A) is a cross-section of the electrode sheet without adhesive layer. The white part in the middle is the current collector. It can be observed that the cross-section of the current collector has obvious burrs. The two sides are electrode material layers. Figure 7 (B) is a cross-section of the electrode sheet with the adhesive layer. The "}" indicates the area of ​​the adhesive layer, which is semi-transparent and completely covers the burrs on the cross-section of the current collector. The adhesive layer is precisely positioned on the cross-section, without extending beyond the edge or overflowing onto the upper or lower surfaces of the electrode material layer. Figure 7 In the process, the total thickness of the electrode plates is approximately 200 μm, and the thickness of the current collector is approximately 13 μm.

[0070] In some embodiments, the width of the adhesive layer is 10 to 50 μm in a direction perpendicular to the upper surface; for example, it can be about 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0071] By using the above-mentioned adhesive layer width, not only can the current collector burrs on the side cut surface of the electrode be better covered, but the adhesive layer is also less likely to break or fall off when the electrode is wound or folded.

[0072] In some embodiments, the viscosity of the raw material at 50°C is ≤100 cmp, and in some embodiments it is ≤50 cps; for example, it can be about 5 cps, 10 cps, 15 cps, 20 cps, 25 cps, 30 cps, 35 cps, 40 cps, 45 cps, 50 cps, etc.

[0073] The electrode sheet has an extremely narrow cross-section, which requires the raw material applied to the cross-section surface to have excellent processing properties to better match high-precision equipment such as electrohydraulic inkjet printers. When the overall viscosity of the raw material is within a suitable range, it is more conducive to matching high-precision equipment and achieving precise control. In some embodiments, the viscosity of the raw material can be adjusted primarily by selecting an active monomer with a suitable viscosity. For example, the viscosity of the active monomer at 50°C can be made below 50 cps.

[0074] The term "viscosity" is a measure of the frictional resistance within a fluid, generally representing the fluid's viscosity. The unit of viscosity is cps (centipoise seconds), an international standard unit for measuring the viscosity of liquids or semi-solids, also known as the neutral viscosity unit. A higher cps indicates a higher viscosity, and vice versa. In this article, viscosity can be measured using the following method: A rotational viscometer (such as a Brookfield rotational viscometer) is used, and the following steps are followed:

[0075] Test steps:

[0076] 1. Prepare the testing equipment and select an appropriate rotor and speed based on the approximate viscosity range of the slurry. For example, a smaller rotor and a higher speed can be selected for low-viscosity slurries, while the opposite is true for high-viscosity slurries.

[0077] 2. Place the slurry sample in a constant temperature device (such as a constant temperature water bath) to stabilize its temperature at the specified test temperature (usually 25°C or other specific temperature).

[0078] 3. Load the slurry into the sample cell, then gently tap the sample cell on your palm to remove air bubbles. Install the sample cell and mount the rotor onto the rotational viscometer, ensuring the rotor is completely submerged in the slurry.

[0079] 4. Open the viscosity test program and set the test parameters, such as rotation speed and test time. For example, you can first test at a lower rotation speed (e.g., 10 rpm) for a period of time (e.g., 30s-120s), and then gradually increase the rotation speed (e.g., 50 rpm, 100 rpm, 200 rpm, etc.), test for a certain time at each rotation speed (e.g., 30s-120s), and set an appropriate settling time (e.g., 15s-60s).

[0080] 5. Start the test and wait for the test to complete.

[0081] 6. Read and record the viscosity value at each rotation speed; take the average viscosity value at that rotation speed over the test period as the final result.

[0082] In some embodiments, the raw materials, by weight, comprise: 10-30 parts acrylic resin, 40-80 parts reactive monomer, and 2-10 parts free radical polymerization initiator. For example, in some embodiments, the weight percentages of acrylic resin in the raw materials may be approximately 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, etc.; the weight percentages of reactive monomer may be approximately 40, 45, 50, 55, 60, 65, 70, 75, 80, etc.; and the weight percentages of free radical polymerization initiator may be approximately 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0083] When the above weight ratio is used, the processing performance of the raw material and the adhesion of the adhesive layer are relatively balanced, which is suitable for accurately forming an adhesive layer on the side cut surface of the electrode sheet, and the adhesive layer has good adhesion.

[0084] In some embodiments, the free radical polymerization initiator includes a photoinitiator. For example, the photoinitiator may be selected from at least one of the following: 1-hydroxycyclohexylphenyl ketone, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, and 2-hydroxy-2-methyl-1-phenylpropanone, etc.

[0085] When a photoinitiator is used, online instant curing can be achieved, improving the processing efficiency of applying the adhesive layer. In particular, when using the aforementioned raw materials with a viscosity ≤50cps at 50°C, and in conjunction with a photoinitiator, it is possible to achieve wired communication between the adhesive layer application equipment (such as an electrohydraulic inkjet printer) and the electrode sheet cutting equipment, without affecting the processing efficiency.

[0086] In some embodiments, the number-average molecular weight of the acrylic resin is 600–5000, and its functionality is ≤10. When the acrylic resin uses the aforementioned lower molecular weight, it has high fluidity, good processing performance, and is suitable for use with high-precision equipment to achieve precise control.

[0087] In some embodiments, a suitable acrylic resin may be selected based on the type of free radical polymerization initiator. For example, when a photoinitiator is used, the acrylic resin may be selected from the following group: EBECRIL 572 (functionality 3, number average molecular weight 1500), EBECRIL 800 (functionality 4, number average molecular weight 780), EBECRIL 837 (functionality 6, number average molecular weight 2700), DSM AgiSyn 707 (functionality 4, number average molecular weight 4700), DSM AgiSyn 720 (functionality 4, number average molecular weight 1000), and DSM NeoRad P-56 (functionality 6, number average molecular weight 1800).

[0088] In some embodiments, the active monomer includes a first monomer, which is a monofunctional monomer. In some embodiments, the first monomer includes at least one selected from the group consisting of isoborneol acrylate, tetrahydrofuran acrylate, bisphenol α-dimethacrylate, propylene-2-ethylethyl acrylate, β-hydroxyethyl methacrylate, lauryl methacrylate, and 2-methaneoxyethyl acrylate.

[0089] By applying the first monomer with the above-mentioned monofunctionality, its crosslinking density is low and its flexibility is relatively good, which is beneficial to improving the toughness of the adhesive layer, so that the adhesive layer is not easy to break or fall off when the electrode is wound or folded.

[0090] Functionality refers to the number of functional groups in a molecule that can participate in a condensation reaction. In this article, monofunctionality means a functionality of 1, and the functional group that can participate in the reaction refers to the acrylate group.

[0091] In some embodiments, the active monomer includes a second monomer having a functionality of 2 or greater; for example, it can be 2, 3, 4, 5, 6, 7, etc. In some embodiments, the second monomer includes at least one selected from the group consisting of: tripropylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, dimethylolethane triacrylate, trimethylolpropane triacrylate, 3-ethoxytrimethylolpropane triacrylate, pentaerythritol pentaacrylate, and dipentaerythritol pentaacrylate.

[0092] By applying a second monomer, the degree of cross-linking of the raw material during curing can be increased, which is beneficial to improving the mechanical strength of the adhesive layer. Consequently, the electrolyte resistance of the electrode is improved, which is beneficial to increasing the battery life.

[0093] In some embodiments, the mass ratio of the first monomer to the second monomer is 10:7 to 20; for example, it can be 10:7, 10:7.5, 10:8, 10:8.5, 10:9, 10:9.5, 10:10, 10:10.5, 10:11, 10:11.5, 10:12, 10:12.5, 10:13, 10:13.5, 10:14, 10:14.5, 10:15, 10:15.5, 10:16, 10:16.5, 10:17, 10:17.5, 10:18, 10:18.5, 10:19, 10:19.5, 10:20, etc.

[0094] When the first monomer and the second monomer are within the above-mentioned mass ratio range, it is beneficial to make the adhesive layer have both high mechanical properties and good toughness. As a result, the following properties of the electrode can be improved accordingly: reducing the risk of adhesive layer cracking when winding and bending the electrode, and improving the electrolyte resistance of the electrode.

[0095] In some embodiments, the active monomer comprises a hydrophobic monomer having a contact angle with water ≥90°. In some embodiments, the hydrophobic monomer comprises at least one selected from the group consisting of: trifluoroethyl (meth)acrylate, hexafluorobutyl (meth)acrylate, dodecafluoroheptyl methacrylate, tetrafluoropropanol methacrylate, and trimethylsilane methacrylate.

[0096] By applying hydrophobic monomers, it is beneficial to improve the resistance of the adhesive layer to humid heat aging and water resistance, thereby improving the stability of the battery cell during long-term storage or use.

[0097] In some embodiments, the hydrophobic monomer accounts for 2% to 10% of the mass of the active monomer; for example, it can be selected from about 2%, 2.2%, 2.6%, 2.8%, 3%, 3.2%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0098] When the above mass ratio is used, the proportion of hydrophobic monomers is more reasonable, which is conducive to balancing the overall performance of the adhesive layer in terms of toughness, mechanical properties and resistance to humid heat aging.

[0099] In some embodiments, the raw material further includes a coupling agent, which includes a silane coupling agent. In some embodiments, the coupling agent includes at least one selected from the group consisting of: 3-aminopropyltriethoxysilane (KH-550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), α-methacryloyloxymethyltrimethylsilane, and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0100] By adding the above coupling agent, the adhesion of the adhesive layer can be further improved, which makes it less likely for the adhesive layer to fall off when the electrode is wound or folded, and also helps to increase the durability of the battery during subsequent use.

[0101] In some embodiments, the raw materials include, by weight, 10-30 parts of acrylic resin, 40-80 parts of active monomer, 2-10 parts of free radical polymerization initiator, and 0.2-5 parts of coupling agent.

[0102] In some embodiments, the raw materials may optionally include pigments, by which a target color adhesive layer can be obtained. In some embodiments, the pigments may be selected from at least one of the following: titanium dioxide, benzidine yellow, phthalocyanine blue, permanent red, pink, royal red, and lightfast deep red.

[0103] In some embodiments, the raw materials include, by weight, 10-30 parts of acrylic resin, 40-80 parts of active monomer, 2-10 parts of free radical polymerization initiator, and 0-2 parts of pigment; and optionally, 0.2-5 parts of coupling agent.

[0104] In some embodiments, the adhesive layer can be formed on the side section of the electrode sheet by providing a raw material, applying the raw material to the side section of the electrode sheet by inkjet printing, and providing suitable conditions for the free radical polymerization initiator to initiate polymerization, thereby forming the adhesive layer on the side section of the electrode sheet. For example, when a photoinitiator is used, providing appropriate light conditions can initiate polymerization.

[0105] In some embodiments, the inkjet printing equipment may be an electrohydrodynamic (EHD) printing machine. When using this equipment, the raw material solution undergoes field-induced rheological changes under a high-voltage electric field to form a Taylor cone, which in turn forms a micro / nano jet with a diameter much smaller than the nozzle's inner diameter. This jet is deposited on the side-section of the electrode sheet, effectively encapsulating any burrs on the side-section. When using this equipment, the width of the formed adhesive layer can be adjusted primarily by modifying the nozzle specifications.

[0106] In some implementations, the viscosity of the raw material at 50°C is ≤100cps or ≤50cps, which is achieved by selecting an active monomer with a suitable viscosity at 50°C, thereby better meeting the requirements of inkjet printing.

[0107] [Positive electrode plate]

[0108] In some embodiments, the positive electrode of the battery cell includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector, the positive electrode material layer comprising a positive electrode active material. In some embodiments, the side section of the positive electrode is provided with the adhesive layer described in this application. In some embodiments, the surface on which the positive electrode material layer is disposed does not have the adhesive layer.

[0109] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, namely the upper surface and the lower surface, and the positive electrode material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0110] In some embodiments, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides 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 / 3Mn 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 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0111] In some embodiments, the positive current collector may 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 may 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 (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.).

[0112] In some embodiments, the positive electrode material layer may optionally include a binder. For example, the binder may include one or more combinations selected from the group consisting of: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0113] In some embodiments, the positive electrode material layer may optionally include a conductive agent. For example, the conductive agent may include one or more combinations selected from the group consisting of: Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0114] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned positive electrode active material, metal oxide particles, and optional conductive agents, binders, and any other components in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto a positive electrode current collector, and after drying and cold pressing, obtaining the positive electrode sheet to be cut; cutting the positive electrode sheet in the middle with a cutter (the cut is the side surface of the positive electrode sheet), and winding it into an electrode roll; before or after winding the electrode roll, the raw material is applied to the side surface of the positive electrode sheet by inkjet printing to provide suitable conditions for the free radical polymerization initiator to initiate polymerization, thereby forming the adhesive layer on the side surface of the positive electrode sheet. In some embodiments, when the side surface of the positive electrode sheet is not provided with an adhesive layer, the steps of providing the adhesive layer are omitted.

[0115] [Negative electrode plate]

[0116] In some embodiments, the negative electrode sheet of the battery cell includes a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer including a negative electrode active material. In some embodiments, the side cross-section of the negative electrode sheet is provided with the adhesive layer described in this application. In some embodiments, the surface on which the negative electrode material layer is disposed does not have the adhesive layer.

[0117] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, namely the upper surface and the lower surface, and the negative electrode material layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0118] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0119] In some embodiments, 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.

[0120] In some embodiments, the negative electrode material layer may optionally include a binder. For example, the binder may include one or more combinations selected from the group consisting of: styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0121] In some embodiments, the negative electrode material layer may optionally include a conductive agent. For example, the conductive agent may include one or more combinations selected from the group consisting of: Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0122] In some embodiments, the negative electrode material layer may also optionally include other additives. For example, other additives may be thickeners (such as sodium carboxymethyl cellulose (CMC-Na)).

[0123] In some embodiments, the negative electrode sheet can be prepared by dispersing the components of the aforementioned negative electrode material layer, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and after drying, cold pressing, and other processes, obtaining the negative electrode sheet to be cut; cutting the negative electrode sheet in the middle with a cutter (the cut is the side section of the negative electrode sheet), and winding it into an electrode roll; before or after winding the electrode roll, the raw material is applied to the side section of the negative electrode sheet by inkjet printing to provide suitable conditions for the free radical polymerization initiator to initiate polymerization, thereby forming the adhesive layer on the side section of the negative electrode sheet. In some embodiments, when the side section of the negative electrode sheet is not provided with an adhesive layer, the steps related to providing the adhesive layer are omitted.

[0124] [Electrolytes]

[0125] 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-like, or solid.

[0126] Liquid electrolytes include electrolyte salts and solvents.

[0127] 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.

[0128] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0129] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0130] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0131] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0132] 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.

[0133] 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.

[0134] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0135] [Isolation Component]

[0136] In some embodiments, the electrode assembly further includes a spacer disposed between the positive electrode and the negative electrode.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] [Structure of the electrode assembly]

[0141] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0142] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0143] In some implementations, the electrode assembly is a stacked structure.

[0144] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0145] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0146] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0147] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0148] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0149] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0150] 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.

[0151] [shell]

[0152] 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.

[0153] 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 impose any particular limitations. For example, Figure 1 This is an example of a square-shell battery cell 5.

[0154] In some implementations, refer to Figure 2 The outer casing includes an end cap 53 and a housing 51. The housing 51 has an opening, and the end cap 53 covers the opening. The housing 51 may have one or more openings. The end cap 53 may also have one or more. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within a receiving cavity formed by the housing 51 and the end cap 53. The electrolyte is immersed in the electrode assembly 52.

[0155] [Electrode terminals]

[0156] 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.

[0157] [Pressure relief mechanism]

[0158] 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.

[0159] 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 forming 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.

[0160] As an example, the pressure relief mechanism can be integrally molded with the housing.

[0161] As an example, the pressure relief mechanism can also be separately installed and connected to the housing.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] Battery device

[0166] 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.

[0167] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0168] 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. Figure 3 This is battery module 4 as an example. (See reference...) Figure 3 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 way.

[0169] 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.

[0170] 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. Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 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 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery pack.

[0171] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] Electrical appliances

[0176] 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. Figure 6 This is an example of an electrical device. The electrical device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0177] Example 1

[0178] This embodiment provides a method for preparing a lithium-ion battery as follows:

[0179] (1) Positive electrode plate

[0180] LiFePO4 as the positive electrode active material, polyvinylidene fluoride (PVDF) as the binder, and acetylene black as the conductive agent are dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 96:2:2. After thorough stirring and mixing, a positive electrode slurry is obtained. The positive electrode slurry is then uniformly coated onto a positive electrode current collector, and after drying and cold pressing, a positive electrode sheet ready for slitting and cutting is obtained.

[0181] Cut the positive electrode sheet to be slit in the middle with a cutter. The cut part after slitting is the side cut surface of the positive electrode sheet. Apply an adhesive layer to the side cut surface of the positive electrode sheet according to the following steps.

[0182] Weigh the following raw materials according to the following parts by weight:

[0183] 20 parts of EBECRIL 572 (functionality 3, number average molecular weight 1500) from the USA, used as the acrylic resin; 76 parts of isoborneol acrylate, used as the first monomer; and 4 parts of 1-hydroxycyclohexylphenyl ketone, used as the photoinitiator. The raw materials were mixed evenly to prepare a slurry with a viscosity of 37 cps at 50°C.

[0184] The prepared adhesive slurry is printed onto the slit side face of the electrode using an electrohydraulic inkjet printer (capable of precise alignment and a minimum inkjet width of 1μm). The nozzle is 2mm away from the electrode, the electrode line speed is 60m / min, and a 395 / 365nm wavelength UV lamp is positioned downstream of the electrode line to achieve online instantaneous curing. The adhesive slurry changes from a liquid state to a solid state after being irradiated by the UV lamp, enabling rapid forming of the adhesive layer onto the slit side face of the electrode. Furthermore, due to the precise control, the upper and lower surfaces of the electrode do not have the adhesive layer.

[0185] Through the above steps, a positive electrode sheet with a adhesive layer on its side section is prepared; the width of the adhesive layer is 40 μm along the thickness direction of the positive electrode sheet (i.e., the direction perpendicular to the upper and lower surfaces of the positive electrode sheet). (Reference) Figure 7 The adhesive layer completely covers the side section of the current collector without extending beyond the edge of the side section of the positive electrode sheet.

[0186] (2) Negative electrode plate

[0187] Artificial graphite as the negative electrode active material, acetylene black as the conductive agent, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC) as the thickener are dissolved in deionized water at a mass ratio of 95:2:2:1 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is then evenly coated onto a copper foil for the negative electrode current collector, dried to obtain a negative electrode film, and then cold-pressed to obtain a negative electrode sheet to be slit and cut.

[0188] The negative electrode sheet to be slit is cut in the middle with a cutter, and the cut is the side section of the negative electrode sheet. This section is then wound into an electrode roll. Following the same paste and inkjet printing method as in the preparation of the positive electrode sheet, an adhesive layer with a width of 40 μm is applied to the side section of the negative electrode sheet. This adhesive layer completely covers the side section of the current collector without extending beyond the edge of the negative electrode sheet's side section.

[0189] (3) Preparation of electrolyte

[0190] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), 1 mol / L LiPF6 was dissolved in an organic solvent (EC / DMC / EMC = 1 / 1 / 1) and stirred until homogeneous to obtain the corresponding electrolyte.

[0191] (4) Preparation of the isolation membrane: conventional polypropylene membrane is used as the isolation membrane.

[0192] (5) Preparation of lithium-ion batteries

[0193] 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 electrodes are then wound to obtain an electrode assembly. The electrode assembly is placed in the battery casing, dried, and then injected with electrolyte. After formation and settling processes, a lithium-ion battery cell is obtained.

[0194] 10,000 battery cells were prepared using the above method, and the following tests were performed. The self-discharge abnormality rate and short circuit rate were statistically analyzed. The results are shown in Table 1.

[0195] 1. Self-discharge abnormality rate of battery electrodes

[0196] The battery is fully charged at 1 / 3C (cutoff voltage 4.0V), and the voltage value V1 is measured. Then, the battery is placed under normal temperature and pressure (25℃±1℃, one atmosphere) for 14 days (i.e., Δt=14d), and the voltage value V2 is measured. The K value is calculated as ΔV / Δt=(V1-V2) / Δt. The unit of K value is mV / d. When the K value exceeds 2mV / d, it is considered to have an abnormal self-discharge. The self-discharge abnormality rate = number of battery cells with discharge abnormalities / total number × 100%.

[0197] 2. Short circuit test

[0198] Use a multimeter to test the short-circuit rate of the battery cells. Set the multimeter to the DCV range; connect the two test leads of the multimeter to the two terminals of the battery and measure the voltage of the cell; if the voltage reading is abnormal or zero, it indicates that the cell has short-circuited. Short-circuit test failure rate = (Number of short-circuited battery cells / Total number of cells) × 100%.

[0199] Example 2

[0200] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0201] When 76 parts of the first monomer, isoborneol acrylate, were replaced with 76 parts of the second monomer, 1,6-hexanediol diacrylate, the viscosity of the adhesive slurry was 35 cps at 50°C.

[0202] Example 3

[0203] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0204] The raw materials for the adhesive layer, by weight, include: 15 parts of EBECREL 57215 (acrylic resin), 30 parts of isoborneol acrylate (first monomer), 48 parts of 1,6-hexanediol diacrylate (second monomer), and 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator). The viscosity of the adhesive layer slurry at 50°C is 26 cps.

[0205] Example 4

[0206] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0207] The raw materials for the adhesive layer, by weight, include: 30 parts of EBECREL 5723 acrylic resin (USA), 30 parts of isoborneol acrylate (first monomer), 49 parts of 1,6-hexanediol diacrylate (second monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-560 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the adhesive layer slurry at 50°C is 45 cps.

[0208] Example 5

[0209] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0210] The raw materials for the adhesive layer, by weight, include: 20 parts of EBECREL 5722 acrylic resin (USA), 30 parts of isoborneol acrylate (first monomer), 47 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl (meth)acrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), and 2 parts of phthalocyanine blue (pigment). The viscosity of the adhesive layer slurry at 50°C is 37 cps.

[0211] Example 6

[0212] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0213] The raw materials for the adhesive layer, by weight, include: 20 parts of EBECREL 5722 acrylic resin (USA), 40 parts of lauryl methacrylate as the first monomer, 30 parts of 1,6-hexanediol diacrylate as the second monomer, 2 parts of trifluoroethyl methacrylate as the hydrophobic monomer, 4 parts of 1-hydroxycyclohexylphenyl ketone as the photoinitiator, 2 parts of KH-550 as the coupling agent, and 2 parts of phthalocyanine blue as the pigment. The viscosity of the adhesive layer slurry at 50°C is 32 cps.

[0214] Example 7

[0215] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0216] The raw materials for the adhesive layer, by weight, include: 15 parts of EBECREL 57215 (acrylic resin), 40 parts of isoborneol acrylate (first monomer), 35 parts of 3-ethoxytrimethylolpropane triacrylate (second monomer), 2 parts of trifluoroethyl (meth)acrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-550 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the adhesive layer slurry at 50°C is 23 cps.

[0217] Example 8

[0218] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0219] The raw materials for the adhesive layer, by weight, include: 20 parts of EBECREL 5722 acrylic resin (USA), 30 parts of isoborneol acrylate (first monomer), 40 parts of 3-ethoxytrimethylolpropane triacrylate (second monomer), 2 parts of trifluoroethyl (meth)acrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-560 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the adhesive layer slurry at 50°C is 35 cps.

[0220] Example 9

[0221] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0222] A colloid layer is applied only to the negative electrode. The colloid layer comprises, by weight, the following components: 20 parts of EBECREL 572 (acrylic resin), 40 parts of isoborneol acrylate (first monomer), 30 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-550 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the colloid slurry at 50°C is 37 cps.

[0223] Example 10

[0224] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0225] A colloid layer is applied only to the negative electrode. The colloid layer comprises, by weight, the following components: 30 parts of EBECREL 572 (acrylic resin), 20 parts of isobornyl acrylate (first monomer), 40 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-550 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the colloid slurry at 50°C is 46 cps.

[0226] Example 11

[0227] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0228] A binder layer is applied only to the negative electrode. The binder layer comprises, by weight, the following components: 15 parts of EBECREL 572 (acrylic resin), 30 parts of lauryl methacrylate (first monomer), 45 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-570 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The binder slurry has a viscosity of 25 cps at 50°C.

[0229] Example 12

[0230] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0231] A colloid layer is applied only to the negative electrode. The colloid layer comprises, by weight, the following components: 20 parts of EBECREL 572 (acrylic resin), 30 parts of isoborneol acrylate (first monomer), 40 parts of 3-ethoxytrimethylolpropane triacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-560 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the colloid slurry at 50°C is 32 cps.

[0232] Example 13

[0233] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0234] A binder layer is applied only to the positive electrode. The binder layer's raw materials, by weight, include: 20 parts of EBECREL 572 (acrylic resin), 40 parts of isoborneol acrylate (first monomer), 30 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-560 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The binder slurry has a viscosity of 34 cps at 50°C.

[0235] Example 14

[0236] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0237] A binder layer is applied only to the positive electrode. The binder layer comprises, by weight, the following components: 30 parts of EBECREL 572 (acrylic resin), 30 parts of isoborneol acrylate (first monomer), 30 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-550 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The binder slurry has a viscosity of 48 cps at 50°C.

[0238] Example 15

[0239] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0240] A binder layer is applied only to the positive electrode. The binder layer comprises, by weight, the following components: 15 parts of EBECREL 572 (acrylic resin), 40 parts of lauryl methacrylate (first monomer), 35 parts of 1,6-hexanediol diacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-550 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The binder slurry has a viscosity of 25 cps at 50°C.

[0241] Example 16

[0242] Except for the following differences, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0243] A colloid layer is applied only to the positive electrode. The colloid layer comprises, by weight, the following components: 20 parts of EBECREL 572 (acrylic resin), 40 parts of isoborneol acrylate (first monomer), 30 parts of 3-ethoxytrimethylolpropane triacrylate (second monomer), 2 parts of trifluoroethyl methacrylate (hydrophobic monomer), 4 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 2 parts of KH-550 (coupling agent), and 2 parts of phthalocyanine blue (pigment). The viscosity of the colloid slurry at 50°C is 38 cps.

[0244] Comparative Example 1

[0245] Except for the absence of an adhesive layer, the preparation and testing were carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0246] Table 1

[0247]

[0248]

[0249] By comparing the examples and Comparative Example 1, it can be seen that by setting an adhesive layer on the side section of the electrode sheet, the self-discharge abnormality rate and short circuit condition of the battery are significantly improved.

[0250] Comparing Examples 1 to 3, it can be seen that when the first monomer and the second monomer are used simultaneously, the battery self-discharge and short circuit are further improved compared to using only the first monomer or the second monomer. This may be due to the more reasonable cross-linking structure when both monomers are used at the same time.

[0251] Example 4 is superior to Examples 1-3, possibly because the addition of a coupling agent further improves the adhesion of the adhesive layer, which helps to reduce the probability of the adhesive layer falling off. As a result, the overall self-discharge rate and short-circuit rate of the battery are reduced in mass production.

[0252] A comparison of Examples 1-3 with Example 5 reveals that adding a certain amount of hydrophobic monomers to the adhesive slurry further reduces the battery's self-discharge rate and short-circuit rate. This is likely due to the increased stability of the adhesive layer after the addition of hydrophobic monomers.

[0253] As shown in Examples 9-12 and Examples 13-16, when the adhesive layer is only provided on the positive or negative electrode, it can also improve the self-discharge rate and short-circuit rate of the battery to a certain extent. If the adhesive layer is provided on the side cut surfaces of both the positive and negative electrodes, the improvement effect is even better.

[0254] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery cell, characterized in that, The electrode includes an electrode sheet, the electrode sheet includes a current collector, the current collector has an upper surface and a corresponding lower surface; at least one of the upper surface and the lower surface is provided with an electrode material layer; Along a direction perpendicular to the upper surface, the electrode sheet has a side section, which includes a current collector side section and an electrode material layer side section; The side section is provided with an adhesive layer, which at least covers the side section of the current collector; the adhesive layer is obtained by polymerization of raw materials including acrylic resin, active monomer and free radical polymerization initiator; the active monomer includes acrylate or acrylate derivative.

2. The battery cell as described in claim 1, characterized in that, The width of the adhesive layer is 10–50 μm in a direction perpendicular to the upper surface.

3. The battery cell as described in claim 1 or 2, characterized in that, The viscosity of the raw material at 50°C is ≤50cps.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The raw materials, by weight, include: 10-30 parts acrylic resin, 40-80 parts active monomer, and 2-10 parts free radical polymerization initiator.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The free radical polymerization initiator includes a photoinitiator.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The active monomer includes a first monomer, wherein the first monomer is a monofunctional monomer; and / or, The first monomer comprises at least one selected from the group consisting of isoborneol acrylate, tetrahydrofuran acrylate, bisphenol α-dimethacrylate, propylene ester-2-ethylethyl acrylate, β-hydroxyethyl methacrylate, lauryl methacrylate, and 2-methaneoxyethyl acrylate.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The active monomer includes a second monomer, the second monomer having a functionality greater than or equal to 2; and / or, The second monomer includes at least one selected from the group consisting of: tripropylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, dimethylolethane triacrylate, trimethylolpropane triacrylate, 3-ethoxytrimethylolpropane triacrylate, pentaerythritol pentaacrylate, and dipentaerythritol pentaacrylate.

8. The battery cell as described in claim 7, characterized in that, The mass ratio of the first monomer to the second monomer is 10:7 to 20.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The active monomer includes a hydrophobic monomer, wherein the hydrophobic monomer has a contact angle with water ≥90°; and / or, The hydrophobic monomer includes at least one selected from the group consisting of trifluoroethyl methacrylate, hexafluorobutyl methacrylate, dodecafluoroheptyl methacrylate, tetrafluoropropanol methacrylate, and trimethylsilane methacrylate.

10. The battery cell as described in claim 9, characterized in that, The hydrophobic monomer accounts for 2% to 10% of the mass of the active monomer.

11. The battery cell according to any one of claims 1 to 10, characterized in that, The raw materials also include coupling agents, including silane coupling agents; and / or, The coupling agent comprises at least one selected from the group consisting of: 3-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, α-methacryloyloxymethyltrimethylsilane, and γ-methacryloyloxypropyltrimethoxysilane; and / or, The raw materials, by weight, include 10-30 parts of acrylic resin, 40-80 parts of active monomer, 2-10 parts of free radical polymerization initiator, and 0.2-5 parts of coupling agent.

12. A method for preparing a single battery cell, characterized in that, A battery cell to be coated with an adhesive layer is provided, comprising an electrode sheet, the electrode sheet comprising a current collector having an upper surface and a corresponding lower surface; at least one of the upper surface and the lower surface is provided with an electrode material layer. Along a direction perpendicular to the upper surface, the electrode sheet has a side section, which includes a current collector side section and an electrode material layer side section; Raw materials including acrylic resin, active monomer and free radical polymerization initiator are provided. The raw materials are placed on the side section of the electrode sheet by inkjet printing. Suitable conditions are provided for the free radical polymerization initiator to initiate polymerization, thereby forming an adhesive layer on the side section of the electrode sheet. The adhesive layer at least covers the side section of the current collector.

13. The preparation method according to claim 12, characterized in that, The inkjet printing device includes a thermoelectric inkjet printer.

14. A battery device, characterized in that, The battery cell includes any one of claims 1 to 11, or a battery cell prepared by the preparation method according to claim 12 or 13.

15. An electrical appliance, characterized in that, It includes the battery cell according to any one of claims 1 to 11, the battery cell prepared by the preparation method according to claim 12 or 13, or the battery device according to claim 14.

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