Lithium ion battery and preparation method thereof
Patent Information
- Application Number
- CN202511628050.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-07
- Publication Date
- 2026-01-27
Smart Images
Figure CN121416636A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, specifically to a lithium-ion battery and its preparation method. Background Technology
[0002] Lithium-ion batteries, as a type of rechargeable battery with high energy density, long cycle life and low self-discharge rate, have been widely used in consumer electronics, electric vehicles and energy storage systems.
[0003] The manufacturing precision and interface quality of lithium-ion batteries directly determine their energy density, safety performance, and cycle life. In the manufacturing of stacked batteries, ensuring tight contact at the interfaces of the multi-layered stacked structure of the positive electrode, separator, and negative electrode, reducing interlayer misalignment, and eliminating air gaps have been long-standing technical challenges.
[0004] Traditional solutions typically employ a method of coating the separator with adhesive and stacking the electrode sheets. This method relies on a final overall hot-pressing process, using external pressure to forcibly compact the cell. Since all the electrode sheets and separators are independent entities, during the final overall hot-pressing, the layers are prone to slippage and misalignment, resulting in extremely uneven internal stress distribution and a tendency to form poor contact points in the central area.
[0005] Therefore, it is necessary to provide a method for preparing lithium-ion batteries to solve the problems of easy slippage and misalignment between layers and uneven internal stress distribution caused by traditional battery stacking and final hot pressing, which leads to poor contact points in the central region. Summary of the Invention
[0006] In view of the above-mentioned technical problems existing in the prior art, the purpose of the present invention is to provide a lithium-ion battery and a method for preparing the same.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] In a first aspect, the present invention provides a method for preparing a lithium-ion battery, comprising the following steps:
[0009] S1. A negative electrode-separator composite is provided, wherein the composite is directly formed by combining a negative electrode and at least one separator;
[0010] S2. Apply adhesive to the surface of the diaphragm that is not in contact with the negative electrode to form an adhesive layer;
[0011] S3. The positive electrode sheet is stacked with the composite, and the positive electrode sheet is in direct contact with the adhesive layer.
[0012] Preferably, step S1 further includes a hot flat pressing process, wherein the negative electrode-separator composite is prepared by the hot flat pressing process.
[0013] Preferably, the adhesive layer in step S2 comprises a lithium salt and an organic compound, wherein the organic compound and the lithium salt can undergo a eutectic reaction to form a eutectic electrolyte layer between the positive electrode and the separator.
[0014] Preferably, the hot pressing process is as follows: the negative electrode sheet and the separator are placed on a hot pressing platform, and uniform hot pressure is applied by the upper and lower hot pressing plates.
[0015] Preferably, the negative electrode-separator composite has a symmetrical structure, wherein the separator is directly laminated to both surfaces of the negative electrode.
[0016] Preferably, step S2 includes:
[0017] (a) Apply adhesive to the surface of the diaphragm on one side of the composite that is not in contact with the negative electrode to form a first adhesive layer, and stack the positive electrode on the first adhesive layer;
[0018] (b) A second adhesive layer is provided on the side of the positive electrode sheet away from the first adhesive layer, and the composite obtained in step S1 is stacked on the second adhesive layer;
[0019] (c) Repeat steps (a) and (b) one or more times.
[0020] In the battery cell stacks obtained through steps (a), (b) and (c), the outermost layer is a separator.
[0021] Preferably, the composite is prepared by two hot-pressing processes, comprising:
[0022] First, the negative electrode sheet and the first separator are subjected to a first hot flat pressing to form a first composite; then, the second separator is stacked on one side surface of the negative electrode sheet of the first composite and subjected to a second hot flat pressing to form the composite.
[0023] Preferably, the pressure, temperature, and time of the first and second hot pressing are controlled independently.
[0024] Preferably, the thickness of the first adhesive layer and the second adhesive layer is independently 1 μm to 20 μm.
[0025] In this application, the term "the composite" refers to the aforementioned "negative electrode-diaphragm composite".
[0026] In a second aspect, the present invention provides a lithium-ion battery, which is prepared by the method described in the first aspect.
[0027] Compared with existing technologies, the present invention has the following beneficial effects:
[0028] The method of this invention involves first directly hot-pressing the negative electrode sheet and the separator to pre-composite them into a composite. Then, adhesive is applied to the surface of the separator in the composite where it is not composited with the negative electrode sheet. This adhesive layer is used to bond the positive electrode sheet to the separator of the composite, resulting in a lithium-ion battery. This method can greatly improve the efficiency of lithium-ion battery coating production, improve interface contact in a timely manner during the stacking process, and enhance battery interface consistency and safety. Its technical principle is as follows: First, hot-pressing the negative electrode sheet and the separator to achieve composite without an adhesive layer on the contact surface avoids the risk of interlayer misalignment, ensures the consistency of the basic units, and ensures uniform contact between them. This means that lithium ions can be uniformly inserted and extracted during charging and discharging, greatly reducing the risk of local lithium dendrite precipitation and separator puncture due to poor interface contact, thus improving battery safety and cycle life. Secondly, the negative electrode and the separator are pre-composite through hot flat pressing to form a stable "separator-negative electrode-separator" basic unit. This basic unit itself has good interfacial contact and a certain structural rigidity. Subsequent coating and stacking are carried out on this stable basis, which greatly reduces the risk of interlayer misalignment in lithium-ion batteries.
[0029] The method of the present invention decomposes the adhesive coating process and embeds it into the lamination process, which can realize online and quasi-continuous production. Compared with the traditional method of preparing all adhesive-coated diaphragms first and then laminating them, or laminating them as a whole and then hot-pressing them, the method of the present invention has a faster production pace, shorter equipment occupancy time, and can greatly improve production efficiency. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the structure of the first composite in one embodiment of the present invention;
[0031] Figure 2 This is a schematic diagram of the structure of the second composite in one embodiment of the present invention;
[0032] Figure 3 This is a schematic diagram of the structure of a lithium-ion battery according to one embodiment of the present invention;
[0033] Wherein, 1, first composite; 11, negative electrode sheet; 12a, first separator; 12b, second separator; 2, composite; 3, first adhesive layer; 4, positive electrode sheet; 41, positive electrode current collector; 42, positive electrode active material layer; 5, second adhesive layer.
[0034] It should be noted that the first diaphragm 12a and the second diaphragm 12b shown in the attached figures are components with the same structure and material; their different names are only used to distinguish the different diaphragms used in the two hot pressing processes. Detailed Embodiments
[0035] Reference will now be made to detailed embodiments of this application, one or more of which are described below. Each example is provided for explanation and not for limitation of this application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.
[0036] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.
[0037] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.
[0038] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0039] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0040] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0041] 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.
[0042] 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.
[0043] In this invention, "first surface" and "second surface" refer to two opposing surfaces of the same layered structure. In a first aspect, this invention provides a method for preparing a lithium-ion battery, comprising the following steps:
[0044] S1. Provide a negative electrode-separator composite, wherein the composite is directly formed by combining a negative electrode and at least one separator;
[0045] S2. Apply adhesive to the surface of the diaphragm that is not in contact with the negative electrode to form an adhesive layer;
[0046] S3. The positive electrode sheet is stacked with the composite, and the positive electrode sheet is in direct contact with the adhesive layer.
[0047] The method of this invention involves first directly hot-pressing the negative electrode sheet and the separator to pre-composite them into a composite. Then, adhesive is applied to the surface of the separator in the composite where it is not composited with the negative electrode sheet to form an adhesive layer. This adhesive layer is then used to bond the positive electrode sheet to the separator in the composite, resulting in a lithium-ion battery. This method significantly improves the efficiency of lithium-ion battery coating production, improves interface contact during stacking, and enhances battery interface consistency and safety. The technical principle is as follows: First, hot-pressing the negative electrode sheet and separator together without an adhesive layer on their contact surfaces avoids the risk of interlayer misalignment, ensures the consistency of the basic units, and ensures uniform contact between them. This means that lithium ions can be uniformly inserted and extracted during charging and discharging, greatly reducing the risk of localized lithium dendrite precipitation and separator puncture due to poor interface contact, thus improving battery safety and cycle life. Secondly, the negative electrode and the separator are pre-composite through hot flat pressing to form a stable "separator-negative electrode-separator" basic unit. This basic unit itself has good interfacial contact and a certain structural rigidity. Subsequent coating and stacking are carried out on this stable basis, which greatly reduces the risk of interlayer misalignment in lithium-ion batteries.
[0048] The method of the present invention decomposes the adhesive coating process and embeds it into the lamination process, which can realize online and quasi-continuous production. Compared with the traditional method of preparing all adhesive-coated diaphragms first and then laminating them, or laminating them as a whole and then hot-pressing them, the method of the present invention has a faster production pace, shorter equipment occupancy time, and can greatly improve production efficiency.
[0049] In some embodiments, step S1 further includes a hot flat pressing process, through which the negative electrode-separator composite is prepared.
[0050] In some implementations, the hot pressing process involves placing the negative electrode sheet and the separator on a hot pressing platform and applying uniform hot pressure through upper and lower hot pressing plates.
[0051] Specifically, the "hot flat pressing process" in this application, also known as hot flat plate pressing, refers to a processing method that uses two flat hot pressing plates to simultaneously apply uniform heat and pressure to materials placed between them (such as the negative electrode sheet and separator in this application), thereby achieving a tight composite between the materials. The core feature of this process is that it can provide a uniform temperature and pressure field in the plane, ensuring that the composite is subjected to consistent stress and heat as a whole, and avoiding local stress or heat concentration.
[0052] In some embodiments, the pressure of the thermal flattening is 0.1MPa to 3MPa, for example, it can be 0.1MPa, 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa or 3MPa, etc.
[0053] In some embodiments, the temperature of the heat flattening is 75°C to 90°C, for example, it can be 75°C, 76°C, 78°C, 80°C, 82°C, 85°C, 88°C or 90°C.
[0054] In some embodiments, the heat flattening time is 1 min to 6 min, for example, it can be 1 min, 2 min, 3 min, 4 min, 5 min or 6 min.
[0055] In some embodiments, the negative electrode-separator composite has a symmetrical structure, wherein the separator is directly laminated to both surfaces of the negative electrode.
[0056] In some implementations, step S2 includes:
[0057] (a) Apply adhesive to the surface of the separator on one side of the composite that is not in contact with the negative electrode to form a first adhesive layer, and stack the positive electrode on the first adhesive layer;
[0058] (b) A second adhesive layer is provided on the side of the positive electrode sheet away from the first adhesive layer, and the composite obtained in step S1 is stacked on the second adhesive layer;
[0059] (c) Repeat steps (a) and (b) one or more times.
[0060] In the battery cell stacks obtained through steps (a), (b) and (c), the outermost layer is a separator.
[0061] Since the electrode sheets are initially fixed through adhesive bonding and lamination during stacking in steps (a) to (c), the structural integrity of the entire battery cell is gradually formed during the manufacturing process. Therefore, after repeating steps (a) and (b) once or multiple times, those skilled in the art can choose to either not hot-press or hot-press as needed, significantly improving process flexibility and adaptability. Moreover, even if hot pressing is performed, this process reduces the pressure and precision requirements of the final overall hot pressing process, thereby reducing yield loss due to improper final hot pressing.
[0062] In some embodiments, the composite is prepared by two hot-pressing processes, including:
[0063] First, the negative electrode sheet and the first separator are subjected to a first hot flat pressing to form a first composite; then, the second separator is stacked on one side of the negative electrode sheet of the first composite and subjected to a second hot flat pressing to form a composite.
[0064] In some implementations, the pressure, temperature, and time of the first and second hot pressing are controlled independently.
[0065] In some embodiments, the thickness of the first and second adhesive layers is independently 1 μm to 20 μm, for example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm. This thickness range aims to balance adhesive strength and ion transport efficiency. A thickness ≥1 μm ensures that the adhesive layer can fully cover the electrode micro-surface, forming a continuous film to provide reliable adhesive integrity and prevent interface peeling; a thickness ≤20 μm effectively controls the transport distance and resistance of lithium ions in the adhesive layer, avoiding increased battery internal resistance and decreased rate performance due to excessive thickness, while ensuring the battery's energy density.
[0066] In some embodiments, the adhesive layer (e.g., the first adhesive layer and / or the second adhesive layer) in step S2 includes a lithium salt and an organic compound. The organic compound, when combined with the lithium salt, can undergo a eutectic reaction to form a eutectic electrolyte layer between the positive electrode and the separator, thereby improving the bonding consistency.
[0067] In some embodiments, the lithium salt includes lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorooxalateborate (LiDFOB), lithium perchlorate (LiClO4), lithium nitrate (LiNO3), lithium bis(oxalateborate)borate (LiBOB), lithium hexafluoroarsenate (LiAsF6), lithium difluorophosphate (LiPO2F2), lithium tetrafluoroborate (LiBF4), lithium chloride (LiCl), lithium trifluoromethanesulfonate (LiCF3SO3), and bis(pentafluoroethylsulfonyl) salts. At least one of lithium imide (LiBETI), lithium tri(pentafluoroethyl)-trifluorophosphate, lithium cyclodifluoromethane-1,1-bis(sulfonyl)imide, lithium cyclodifluoromethane-1,1-bis(sulfonyl)imide, lithium bis(perfluoroethanesulfonyl)imide, lithium bis(fluoromalonic acid)borate, lithium tetracyanoborate, lithium dicyanotriazole, lithium dicyano-trifluoromethyl-imidazolium, and lithium dicyano-pentafluoroethyl)-imidazolium, preferably at least one of lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorosulfonylimide, lithium difluorooxalateborate, and lithium dioxalateborate.
[0068] In some embodiments, the organic compound includes at least one of sulfone compounds, amide compounds, nitrile compounds, alcohol compounds, imidazole compounds, crown ether compounds, or derivatives of the above substances.
[0069] In some embodiments, the organic compound includes at least one selected from N-methylacetamide, acetamide, succinate, urea, dimethyl sulfoxide, methanol, and ethylene glycol.
[0070] In some embodiments, the molar ratio of lithium salt to organic compound is 1:(1~5), for example, but not limited to 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5.
[0071] In some implementations, the positive electrode, negative electrode, and separator are all cut to size.
[0072] In one embodiment, the negative electrode sheet has a length range of 120mm to 350mm, for example, 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 200mm, 220mm, 240mm, 260mm, 280mm, 300mm, 310mm, 320mm, 330mm, or 350mm. The width range of the negative electrode sheet is 10mm to 120mm, for example, 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, or 120mm. The specific size can be adjusted according to actual needs and is not limited here.
[0073] In some implementations, the negative electrode is slightly larger than the positive electrode.
[0074] In some implementations, the diaphragm is larger than the positive and negative electrodes to better isolate them and prevent short circuits caused by contact between the positive and negative electrodes.
[0075] In some embodiments, the positive electrode includes a positive current collector and a positive active material layer; the negative electrode includes a negative current collector and a negative active material layer.
[0076] The embodiments of the present invention do not specifically limit the types of positive electrode current collector, negative electrode current collector, positive electrode active material layer, and negative electrode active material layer, and those skilled in the art can select them as needed.
[0077] In some embodiments, the positive current collector can be at least one of aluminum foil or carbon-coated aluminum foil.
[0078] In some embodiments, the positive electrode active material layer includes a positive electrode active substance, a first conductive agent, and a first binder.
[0079] In some embodiments, the positive electrode active material is one of layered oxides, spinel-type active materials, olivine-type active materials, and polyanionic active materials.
[0080] In some embodiments, the layered oxide (e.g., rock salt layered oxide) comprises one or more lithium-based cathode active materials selected from: LiCoO2 (LCO), LiNi x Mn y Co 1-x-y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi 1-x-y Co x Al y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi x Mn1-x O2 (where 0 ≤ x ≤ 1), and Li 1+x MO2 (where M is one of Mn, Ni, Co and Al, 0≤x≤1).
[0081] In some embodiments, the spinel-type active material comprises one or more lithium-based cathode active materials selected from LiMn2O4 (LMO) and LiNi. x Mn 1.5 O4.
[0082] In some embodiments, the olivine-type active material comprises one or more lithium-based cathode active materials, LiMPO4 (where M is at least one of Fe, Ni, Co, and Mn).
[0083] In some embodiments, the polyanionic active material comprises, for example, a phosphate such as LiV2(PO4). 24 And / or silicates such as LiFeSiO4.
[0084] In some embodiments, the first conductive agent may comprise any conductive material, as long as it does not cause a chemical change. Non-limiting examples of conductive materials include carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
[0085] In some embodiments, the carbon-based material includes, but is not limited to, at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fiber.
[0086] In some embodiments, the metal-based material includes, but is not limited to, at least one of metal powder and metal fiber, such as copper, nickel, aluminum, silver, etc.
[0087] In some embodiments, non-limiting examples of the first adhesive include one or more of polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, and nylon.
[0088] In some embodiments, the negative current collector includes at least one of copper foil or carbon-coated copper foil.
[0089] In some embodiments, the negative electrode active material layer includes a negative electrode active substance, a second conductive agent, and a second binder.
[0090] In some embodiments, the negative electrode active material includes at least one of artificial graphite, natural graphite, elemental silicon, silicon-carbon materials, and silicon-oxygen materials.
[0091] In some embodiments, the second conductive agent includes at least one of carbon black, Ketjen black, acetylene black, carbon nanotubes, and graphene.
[0092] In some implementations, the second adhesive includes CMC and / or SBR.
[0093] In a second aspect, the present invention provides a lithium-ion battery, which is prepared by the method described in the first aspect.
[0094] Example 1
[0095] This embodiment provides a method for preparing a lithium-ion battery, the method including a composite step of a negative electrode sheet and a separator, and the preparation method is carried out in the following order:
[0096] S1. First, the negative electrode 11 and the first separator 12a are subjected to a first hot flat pressing to form the first composite 1 (see structural schematic diagram). Figure 1 Then, the second separator 12b is stacked on one side of the negative electrode sheet of the first composite 1, and a second hot flat pressing is performed to form a composite 2 with a symmetrical structure. See the schematic diagram of the structure of composite 2. Figure 2 ;
[0097] S2, Stacking:
[0098] (a) Apply adhesive to the surface of the diaphragm 12 on one side of the composite 2 that is not in contact with the negative electrode 11 to form a first adhesive layer 3. Stack the positive electrode 4 on the first adhesive layer 3. The positive electrode 4 includes a positive current collector 41 and positive active material layers 42 disposed on both sides of the positive current collector 41. The positive active material layers 42 are in contact with the first adhesive layer 3.
[0099] (b) Apply adhesive to the side of the positive electrode 4 away from the first adhesive layer 3 to form a second adhesive layer 5, and continue to stack the composite 2 prepared in step S1 on the second adhesive layer 5;
[0100] (c) Repeat steps (a) and (b) twice, that is, continue to apply adhesive to the surface of the separator 12 of the composite 2 that is not in contact with the negative electrode 11 to form a first adhesive layer 3. Place the positive electrode 4 on the first adhesive layer 3. The positive electrode 4 includes a positive current collector 41 and positive active material layers 42 disposed on both sides of the positive current collector 41. The positive active material layers 42 are in contact with the first adhesive layer 3. Then apply adhesive to the side of the positive electrode 4 away from the first adhesive layer 3 to form a second adhesive layer 5. Stack the composite 2 on the second adhesive layer 5 to obtain the cell stack. See the schematic diagram of its structure. Figure 3 .
[0101] In this embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on both sides of the negative electrode current collector.
[0102] Comparative Example 1
[0103] The two sides of the separator are coated with adhesive, and the separators are stacked in the following order: negative electrode, separator, positive electrode, separator, negative electrode, separator, positive electrode, separator, negative electrode, ... The separator is bonded to the positive electrode and negative electrode respectively using the adhesive layers on the two sides of the separator. After the stacking is completed, the last step is hot pressing to prepare the lithium-ion battery.
[0104] Test methods and test results:
[0105] (1) The maximum cumulative misalignment was tested on the complete cells prepared in Example 1 and Comparative Example 1:
[0106] The measurement is performed as follows: the cell is fixed and cut to obtain a flat cross-section. Using the edge of the bottommost electrode as a baseline, the offset of the edges of all other layers (positive and negative electrodes) relative to this baseline is measured. The sum of the absolute values of the maximum positive and the maximum negative values is the maximum cumulative misalignment.
[0107] (2) Taking the production of 50 battery cells as an example, within the same specified time, the number of qualified batteries that Example 1 and Comparative Example 1 can complete are counted, and the relative production efficiency is calculated based on the output of Example 1 (100%).
[0108] The test results are shown in Table 1.
[0109]
[0110] The battery cell prepared in Example 1 has a maximum cumulative misalignment of ≤0.5mm at the electrode edge, while the battery cell prepared in Comparative Example 1 has a misalignment of ≥1.2mm. This demonstrates that the present invention significantly improves the stacking accuracy and effectively solves the problems of easy slippage and misalignment between layers and uneven internal stress distribution leading to poor contact points in the central area caused by traditional battery stacking and final hot pressing. Moreover, it improves the production efficiency of the battery, thanks to the fact that the pre-composite process simplifies the complexity of subsequent stacking operations and reduces production time and defect rate.
[0111] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for preparing a lithium-ion battery, characterized in that, Includes the following steps: S1. A negative electrode-separator composite is provided, wherein the composite is directly formed by combining a negative electrode and at least one separator; S2. Apply adhesive to the surface of the diaphragm that is not in contact with the negative electrode to form an adhesive layer; S3. The positive electrode sheet is stacked with the composite, and the positive electrode sheet is in direct contact with the adhesive layer.
2. The method for preparing a lithium-ion battery according to claim 1, characterized in that, Step S1 also includes a hot flat pressing process, through which the negative electrode-separator composite is prepared.
3. The method for preparing a lithium-ion battery according to claim 1, characterized in that, The adhesive layer in step S2 includes lithium salt and organic compound. The organic compound combines with the lithium salt to undergo a eutectic reaction to form a eutectic electrolyte layer between the positive electrode and the separator.
4. The method for preparing a lithium-ion battery according to claim 2, characterized in that, The hot pressing process is as follows: the negative electrode sheet and the separator are placed on a hot pressing platform, and uniform hot pressure is applied by the upper and lower hot pressing plates.
5. The method for preparing a lithium-ion battery according to any one of claims 2 or 4, characterized in that, The negative electrode-separator composite has a symmetrical structure, wherein the separator is directly laminated to both surfaces of the negative electrode.
6. The method for preparing a lithium-ion battery according to claim 5, characterized in that, Step S2 includes: (a) Apply adhesive to the surface of the diaphragm on one side of the composite that is not in contact with the negative electrode to form a first adhesive layer, and stack the positive electrode on the first adhesive layer; (b) A second adhesive layer is provided on the side of the positive electrode sheet away from the first adhesive layer, and the composite obtained in step S1 is stacked on the second adhesive layer; (c) Repeat steps (a) and (b) one or more times; In the battery cell stacks obtained through steps (a), (b) and (c), the outermost layer is a separator.
7. The method for preparing a lithium-ion battery according to claim 5, characterized in that, The composite is prepared by two hot-pressing processes, including: First, the negative electrode sheet and the first separator are subjected to a first hot flat pressing to form a first composite; then, the second separator is stacked on one side surface of the negative electrode sheet of the first composite and subjected to a second hot flat pressing to form the composite.
8. The preparation method according to claim 7, characterized in that, The pressure, temperature, and time of the first and second heat pressing are controlled independently.
9. The method for preparing a lithium-ion battery according to any one of claims 1-8, characterized in that, The thickness of the first adhesive layer and the second adhesive layer are each independently 1 μm ~ 20 μm.
10. A lithium-ion battery, characterized in that, The lithium-ion battery is prepared by the method described in any one of claims 1-9.