Electrode assembly, battery and electric equipment

Abstract

The invention relates to an electrode assembly, a battery and electric equipment. The electrode assembly comprises a negative pole piece, a diaphragm and a positive pole piece, the diaphragm is arranged on one side of the negative pole piece, the diaphragm comprises a base film and an adhesive layer, the adhesive layer is arranged on at least one side of the base film, the adhesive layer comprises a first polymer, and the first polymer is a polymer with one of a urethane bond and an epoxy bond; the positive pole piece is arranged on one side, provided with the adhesive layer, of the base film; the positive pole piece comprises an active material layer, the active material layer comprises a second polymer, and the second polymer is a polymer with amino and hydroxyl.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery, and an electrical device. Background Art

[0002] With the continuous development of battery technology, the smoothness requirements of the cell interface of lithium-ion batteries can be met by introducing a polymer coating on the surface of the diaphragm base film. However, due to equipment limitations or energy consumption cost requirements, it is not possible to equip a tunnel furnace that can preheat the bare cell in advance. There is an urgent need to develop a polymer-coated diaphragm that can produce a high adhesion effect under room temperature pressing conditions. Under the constraints of room temperature conditions and short aging time, higher pressure must be used for pressing to achieve a good adhesion effect between the polymer-coated diaphragm and the electrode and to meet the smoothness of the cell interface. However, when the bare cell is subjected to high external pressure, the porous structure inside the diaphragm base film is easily deformed, which affects the ion transmission efficiency of the battery. Therefore, there is an urgent need to develop a polymer-coated diaphragm that can produce a high adhesion effect under room temperature and low-pressure pressing conditions. Summary of the Invention

[0003] In view of this, the present application provides an electrode assembly, a battery and an electrical device, wherein the diaphragm of the electrode assembly and the positive electrode plate still have good bonding performance under room temperature and low pressure pressing conditions.

[0004] The present application provides an electrode assembly, which includes a negative electrode plate, a separator and a positive electrode plate, wherein the separator is arranged on one side of the negative electrode plate, the separator includes a base film and a glue layer, the glue layer is arranged on at least one side of the base film, the glue layer includes a first polymer, and the first polymer is a polymer having one of a urethane bond and an epoxy bond; the positive electrode plate is arranged on the side of the base film where the glue layer is provided; the positive electrode plate includes an active material layer, and the active material layer includes a second polymer, and the second polymer is a polymer having an amino group and a hydroxyl group.

[0005] Furthermore, the first polymer includes one of polyurethane, amino acrylic resin, epoxy resin, and epoxy acrylate; the second polymer includes one of polydopamine, a polydopamine derivative, a copolymer containing dopamine, and chitosan.

[0006] Furthermore, the electrode assembly includes at least one of the following features: the mass ratio q1 of the first polymer to the second polymer satisfies the range: 10 / 3≤q1≤100; the weight average molecular weight M1 of the first polymer satisfies the range: 800≤M1≤30000; the weight average molecular weight M2 of the second polymer satisfies the range: 2000≤M2≤200000.

[0007] Furthermore, the electrode assembly includes at least one of the following features: in the glue layer, the mass percentage content a1 of the first polymer is in the range of: 0.5%≤a1≤5%; in the active material layer, the mass percentage content a2 of the second polymer is in the range of: 0.1%≤a2≤2%.

[0008] Furthermore, the adhesive layer further comprises a surfactant, and the surfactant is selected from at least one of polyvinyl alcohol, epoxysilane hydroxyl, ethyl cellulose, fatty acid ester, carboxylic acid ester, lactic acid ester and cellulose ester.

[0009] Furthermore, a mass ratio q2 of the first polymer to the surfactant satisfies the range of 5≤q2≤50.

[0010] Furthermore, in the adhesive layer, the mass percentage content a3 of the surfactant is in the range of: 0.1%≤a3≤2%.

[0011] Furthermore, the negative electrode sheet, the separator and the positive electrode sheet are stacked and then wound to form a wound structure. The electrode assembly is pressed for 40 seconds at room temperature. The unit area pressure of the separator is P. In the innermost circle of the wound structure, the peel strength between the separator and the positive electrode sheet is Q. The coverage of the adhesive layer on the base film is S. Then, the electrode assembly satisfies the relationship: 0≤(SP×Q)≤20.

[0012] Furthermore, the electrode assembly includes at least one of the following features: the coverage S of the glue layer on the base film is in the range of: 5%≤S≤30%, and / or; the electrode assembly is pressed for 40 seconds at room temperature, and the unit area pressure P of the diaphragm is in the range of: 2.8MPa≤P≤4.8MPa, and / or; in the innermost circle of the winding structure, the peel strength Q between the diaphragm and the positive electrode sheet is in the range of: 1.5N / m≤Q≤5N / m.

[0013] The present application also provides a battery, comprising: an electrode assembly provided in the present application and an electrolyte, wherein the electrolyte is used to soak at least a portion of the electrode assembly.

[0014] The present application also provides an electrical device, which includes: a device body and a battery provided in the present application, and the battery supplies power to the device body.

[0015] In the present application, the negative electrode sheet, the separator, and the positive electrode sheet are stacked, wound, and pressed to form the electrode assembly. The positive electrode sheet is disposed on the side of the separator where the adhesive layer is disposed. In other words, the active material layer of the positive electrode sheet is disposed opposite the adhesive layer. The adhesive layer comprises a first polymer, and the active material layer comprises a second polymer, wherein the second polymer is a polymer having amino and hydroxyl groups. When the first polymer is a polymer having urethane bonds, the urethane bonds contain strongly electronegative oxygen and nitrogen atoms. The hydrogen atoms in the amino and hydroxyl groups of the second polymer can interact with the charge between the nitrogen and oxygen atoms in the urethane bonds and form hydrogen bonds, thereby improving the interfacial adsorption between the adhesive layer and the active material layer. Similarly, when the first polymer is a polymer having epoxy bonds, the amino and hydroxyl groups in the second polymer can form hydrogen bonds with the oxygen atoms in the epoxy groups. This intermolecular force can enhance the compatibility and adhesion between the first and second polymers, thereby improving the interfacial adsorption between the adhesive layer and the active material layer. During the pressing process of the electrode assembly, since the first polymer and the second polymer can form hydrogen bonds and improve the interfacial adsorption force between the glue layer and the active material layer, specifically, in the inner circle of the wound structure formed by the positive electrode sheet, the separator and the negative electrode sheet, the positive electrode sheet and the separator have good bonding strength and fit, so that the electrode assembly can achieve a high bonding effect between the glue layer and the active material layer even under room temperature and low pressure pressing conditions, thereby improving the preparation performance of the electrode assembly. Specifically, the electrode assembly can produce a good bonding effect under low or moderate pressure, avoiding damage to the structure of the base film under high pressure, and can avoid changing the porosity and tortuosity of the positive electrode sheet and / or the negative electrode sheet, so as to avoid destroying the ion transmission path and affecting the ion transmission capacity of the separator. When the electrode assembly is applied to a battery, the battery has good charge and discharge performance and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a schematic structural diagram of an energy storage system according to an embodiment of the present application;

[0018] Figure 2 A schematic structural diagram of an energy storage system according to another embodiment of the present application;

[0019] Figure 3This is a structural diagram of an energy storage system according to another embodiment of the present application;

[0020] Figure 4 Schematic diagram of the cross-sectional structure of an electrode assembly according to an embodiment of the present application;

[0021] Figure 5 This is a schematic cross-sectional view of an electrode assembly according to another embodiment of the present application;

[0022] Figure 6 A schematic cross-sectional view of a diaphragm according to an embodiment of the present application;

[0023] Figure 7 This is a schematic cross-sectional view of a diaphragm according to another embodiment of the present application;

[0024] Figure 8 Schematic diagram of the cross-sectional structure of a positive electrode sheet according to an embodiment of the present application;

[0025] Figure 9 A schematic diagram of a partially exploded structure of a battery according to an embodiment of the present application;

[0026] Figure 10 This is the scanning electron microscope spectrum of the adhesive layer of the diaphragm of Example 1 of the present application Figure 1 ;

[0027] Figure 11 This is the scanning electron microscope spectrum of the adhesive layer of the diaphragm of Example 1 of the present application Figure 2 ;

[0028] Figure 12 This is a diagram showing the interface wrinkles of the negative electrode sheet in the inner ring of the electrode assembly of Example 1 after full charge;

[0029] Figure 13 This is a diagram showing the interface wrinkles of the negative electrode sheet in the inner ring of the electrode assembly of Comparative Example 1 after full charge;

[0030] Figure 14 This is a schematic structural diagram of an electrical device according to an embodiment of the present application;

[0031] Figure 15 This is a circuit block diagram of an electrical device according to an embodiment of the present application.

[0032] Description of reference numerals:

[0033] 100-electrode assembly, 110-negative electrode plate, 120-diaphragm, 121-base film, 122-glue layer, 123-ceramic coating, 130-positive electrode plate, 131-active material layer, 132-positive electrode current collector layer, 200-battery, 210-electrolyte, 300-electrical equipment, 310-equipment body, 400-energy storage system, 410-first electric energy conversion device, 420-first user load, 430-second user load, 440-energy storage device, 450-high-voltage cable, 460-second electric energy conversion device, 470-energy storage cabinet, 480-photovoltaic storage and charging station, 490-automobile. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0036] References herein to "embodiments" or "implementations" mean that a particular feature, structure, or characteristic described in connection with the embodiments or implementations may be included in at least one embodiment of the present application. The appearance of such phrases in various places in the specification does not necessarily refer to the same embodiment, nor do they constitute independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0037] With the continuous advancement of battery technology, the introduction of polymer coatings on the surface of the separator base film can meet the smoothness requirements of the cell interface in lithium-ion batteries. However, due to equipment limitations and energy cost requirements, tunnel furnaces that can preheat bare cells are not available. There is an urgent need to develop polymer-coated separators that can achieve high adhesion even under room temperature pressing conditions. Under the constraints of room temperature and short aging time, high pressing pressures must be used to achieve good adhesion between the polymer-coated separator and the electrode and achieve a smooth cell interface.

[0038] However, when bare cells are subjected to high external pressure, the porous structure inside the diaphragm base film is easily deformed, and even the porosity and tortuosity of the electrode plates are changed, which seriously affects the ion transmission capacity of the diaphragm and even destroys the transmission path of lithium ions. Therefore, if high pressure is used in the pressing process, it is easy to cause low energy efficiency of the cell and poor cycle performance of the battery. It is necessary to reduce the pressure of pressing bare cells; however, reducing the pressing pressure will weaken the bonding effect under cold pressing conditions. Specifically, when the pressure is reduced, the effective bonding area between the diaphragm and the electrode plates becomes smaller, affecting the flatness of the cell interface. Therefore, it is necessary for polymer-coated diaphragms to produce better bonding under lower or moderate pressure, which not only ensures the flatness of the cell interface, but also does not have a significant impact on the internal structure of the diaphragm and the electrode plates, thereby maintaining the energy efficiency and cycle performance of the cell.

[0039] Specifically, due to the relatively thick thickness of the bare cell (30mm-34mm), the pressures on the inner and outer rings of the bare cell will be different under short-term pressing at room temperature, and the bonding strength of the inner ring will be worse under low pressure. If the bonding performance between the positive electrode and the diaphragm is poor, the diaphragm may be locally wrinkled or displaced due to capillary action during the infiltration of the electrolyte. At this time, the positive electrode cannot constrain the diaphragm, causing the diaphragm to deform and squeeze the negative electrode, making it impossible to ensure a close fit between the electrode and the diaphragm, and ultimately causing wrinkles on the negative electrode during the charge and discharge cycle, increasing the risk of purple spots and lithium precipitation. Therefore, under low-pressure conditions, the inner ring has the greatest impact on the bonding between the bare cell diaphragm and the electrode. Therefore, there is an urgent need to develop a polymer-coated diaphragm that can produce a high bonding effect under room temperature and low-pressure pressing conditions.

[0040] It can be understood that in the terminology of this application, "bare cell" refers to a battery cell that is not encapsulated in a shell and is composed only of basic components such as electrode plates (positive electrode plates and negative electrode plates), diaphragms, etc. It contains the key structures and materials to realize the battery's charging and discharging functions.

[0041] Since the energy people need is highly time- and space-dependent, in order to rationally utilize energy and improve energy utilization, it is necessary to use a medium or device to store one form of energy in the same form or convert it into another form of energy, and then release it in a specific form based on future application needs. Currently, the main way to generate green electricity is to develop green energy such as photovoltaics and wind power to replace fossil energy.

[0042] Currently, the generation of green electricity generally relies on photovoltaics, wind power, and hydropower. However, wind and solar energy are generally intermittent and highly volatile, which can cause grid instability, insufficient electricity during peak hours, and excessive electricity during off-peak hours. Unstable voltage can also damage electricity. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar power curtailment". To solve these problems, we must rely on energy storage. This means converting electrical energy into other forms of energy through physical or chemical means and storing them. When needed, this energy is converted into electrical energy and released. Simply put, energy storage is like a large "power bank", storing electricity when photovoltaic and wind energy are sufficient and releasing the stored electricity when needed.

[0043] Taking electrochemical energy storage as an example, this solution provides an energy storage device 440, which is applied to the energy storage system 400. The energy storage device 440 is equipped with a group of chemical batteries, which mainly use the chemical elements in the battery 200 as energy storage media. The charging and discharging process is accompanied by chemical reactions or changes in the energy storage medium. Simply put, the electricity generated by wind and solar energy is stored in the chemical battery. When the use of external electricity reaches a peak, the stored electricity is released for use, or transferred to places where electricity is scarce for use.

[0044] Currently, energy storage (i.e., energy storage) has a wide range of application scenarios, including power generation side energy storage, grid side energy storage, and power consumption side energy storage. The corresponding types of energy storage devices 440 include:

[0045] (1) Large-scale energy storage power stations used in wind power and photovoltaic power stations can help renewable energy generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power supply on the power supply side, energy storage power stations can achieve load matching of electricity in time and space, enhance the ability to absorb renewable energy, reduce instantaneous power changes, reduce the impact on the power grid, improve the absorption of new energy generation, and are of great significance in grid system backup, alleviating peak load power supply pressure, and peak and frequency regulation.

[0046] (2) The energy storage container used on the grid side mainly functions as peak shaving, frequency regulation, and relief of grid congestion. It can realize peak shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak period of electricity load, thereby achieving a balance between electricity production and consumption.

[0047] (3) Small energy storage cabinets used on the power consumption side, whose main functions are self-generation and self-use of electricity, peak-valley price arbitrage, capacity cost management, and improving power supply reliability. According to different application scenarios, energy storage on the power consumption side can be divided into industrial and commercial energy storage cabinets, household energy storage devices 440, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the power market that implements peak-valley electricity prices, by charging the energy storage system 400 when the electricity price is low and discharging the energy storage system 400 when the electricity price is high, peak-valley electricity price arbitrage is achieved, thereby reducing electricity costs. In addition, industrial enterprises that are subject to two-part electricity prices can use the energy storage system 400 to store energy during low electricity consumption and discharge it during peak load, thereby reducing peak power and the maximum demand reported, and achieving the purpose of reducing capacity electricity charges. Household photovoltaic storage can improve the level of self-generation and self-use of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installation is driven. Considering that photovoltaic power generation occurs during the day, while user loads are generally higher at night, deploying energy storage can better utilize photovoltaic power, increasing self-generation and self-consumption while reducing electricity costs. Furthermore, energy storage is required for backup power in areas such as communication base stations and data centers.

[0048] In some embodiments, see Figure 1 , Figure 1 This is a schematic diagram of the structure of an energy storage system 400 according to an embodiment of the present application. Figure 1 The embodiment is described by taking the household energy storage scenario in the user-side energy storage as an example, but the energy storage device 440 of the present application is not limited to the household energy storage scenario.

[0049] The present application provides an energy storage system 400, which includes a first electric energy conversion device 410 (photovoltaic panel), a first user load 420 (household lamps), a second user load 430 (such as air conditioners and other household appliances), and an energy storage device 440. The energy storage device 440 is a small energy storage box that can be mounted on an outdoor wall by wall-mounting. The energy storage device 440 of the present application is not limited to wall-mounting and can also be placed in the user's residence by other means. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices. The energy storage device 440 is used to store the electrical energy and supply it to lamps and household appliances for use during peak electricity prices, or to supply power when the power grid is outage / power outage.

[0050] In some embodiments, see Figure 2 , Figure 2 This is a structural diagram of an energy storage system 400 according to another embodiment of the present application. Figure 2 The embodiment is described using the shared energy storage scenario on the power generation / distribution side as an example. The energy storage device 440 of the present application is not limited to the energy storage scenario on the power generation / distribution side.

[0051] The present application provides an energy storage system 400, which includes: a high-voltage cable 450, a first electric energy conversion device 410, a second electric energy conversion device 460 and an energy storage device 440 provided in the present application. In some embodiments of the power generation side scenario, the second electric energy conversion device 460 can be a wind power conversion device. Since the electric energy generated by wind power conversion is volatile, random and intermittent, the unstable electric energy output by the wind power conversion device can be stored in the energy storage device 440 by connecting to the grid. The energy storage device 440 is connected to the high-voltage cable and outputs smooth electric energy to the power distribution network for use, thereby realizing peak and frequency regulation and stable operation of the power grid; or, wind power The conversion device is always connected to the high-voltage cable. Under normal power generation conditions, the electric energy output by the wind power conversion device is supplied to the power consumption side of the distribution network through the high-voltage cable. When the current power load is low and the wind power conversion device generates excess power, the excess power is first stored in the energy storage device 440, reducing the wind and solar power abandonment rates and improving the problem of new energy power generation and consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 440 in conjunction with the high-voltage cable 450 in a grid-connected mode to the power consumption side, providing peak shaving, frequency regulation, standby and other services for the power grid operation, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling of the power grid, and alleviating the power supply pressure of the power grid.

[0052] In some embodiments on the distribution network side, the first power conversion device 410 can be a photovoltaic power conversion device, and the energy storage device 440 is connected to the high-voltage cable 450 and installed between the downstream of the high-voltage cable 450 and the user load. The electric energy output by the photovoltaic power conversion device is stored in the energy storage device 440, which can respond in time and act as a backup power supply when a fault occurs in the power grid / distribution network; or, it can alleviate the line congestion when a line congestion occurs in the high-voltage cable 450 transmission line, and provide power supply support when the power grid is planned to be expanded to delay the economic pressure caused by the expansion of the power grid / distribution network.

[0053] Optionally, the first electric energy conversion device 410 may include but is not limited to a wind power conversion device, and the second electric energy conversion device 460 may include but is not limited to a photovoltaic power conversion device. The first electric energy conversion device 410 and the second electric energy conversion device 460 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electric energy.

[0054] Optionally, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be recharged to activate the active material after discharge and continue to be used. The battery cell may be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, or the like, and this application does not impose specific limitations on this.

[0055] In some embodiments, see Figure 3 , Figure 3 This is a structural diagram of an energy storage system 400 according to another embodiment of the present application. Figure 3 The embodiment is described using the industrial and commercial side energy storage scenario as an example. The energy storage device 440 of the present application is not limited to the generation / distribution side energy storage scenario.

[0056] The present application provides an energy storage system 400, which includes: an energy storage cabinet 470, a high-voltage cable 450, a factory equipped with a first power conversion device 410, a photovoltaic storage and charging station 480 equipped with a second power conversion device 460, and a car 490. In some embodiments of the industrial and commercial side scenario, the first power conversion device 410 can be a photovoltaic panel, which converts solar energy into electricity and stores it in the energy storage cabinet 470 of the factory. In the event of a power outage in the power grid, the energy storage cabinet 470 is used to supply power to ensure safe, stable and continuous operation of the factory. Or when the power load of the factory is high, the power grid issues a command to use the electricity stored in the energy storage cabinet 470 in conjunction with the high-voltage cable 450 in a grid-connected mode to transmit electricity to the factory for use, providing peak / frequency regulation, backup and other services for the operation of the power grid. In addition, the second power conversion device 460 can also be a photovoltaic panel, which converts solar energy into electricity and stores it in the energy storage cabinet 470 of the photovoltaic storage and charging station 480, and directly charges the car 490 through the photovoltaic storage and charging station 480, which is fast and convenient.

[0057] Optionally, the first power conversion device 410 and the second power conversion device 460 may include but are not limited to photovoltaic power conversion devices. The first power conversion device 410 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electrical energy.

[0058] Optionally, the energy storage cabinet 470 may include but is not limited to energy storage application scenarios such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems or temporary power supply systems, and is also used in data centers, military equipment, aerospace, charging piles, electric vehicles and other fields.

[0059] Optionally, energy storage cabinet 470 may include, but is not limited to, single cells, or integrated battery systems such as battery modules, battery packs, battery clusters, mobile power supplies, and energy storage cabinets / containers comprised of these cells. The energy storage cabinet 470 provided in this embodiment of the present application may be used in, but is not limited to, the products listed above. Other application forms are also possible. This embodiment of the present application does not impose strict limitations on the application form of energy storage cabinet 470. This embodiment of the present application uses energy storage cabinet 470 with a multi-cell battery as an example.

[0060] Optionally, the single battery 200 constituting the energy storage cabinet 470 may be, but is not limited to, at least one of a cylindrical battery, a square battery, a prismatic battery, or batteries of other shapes.

[0061] Optionally, the energy storage device 440 may include but is not limited to energy storage application scenarios such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems or temporary power supply systems, and is also used in data centers, military equipment, aerospace, charging piles, electric vehicles and other fields.

[0062] Optionally, energy storage device 440 may include, but is not limited to, single cells, or integrated battery systems such as battery modules, battery packs, battery clusters, mobile power supplies, energy storage cabinets, and energy storage containers. The energy storage device 440 provided in this embodiment of the present application may be, but is not limited to, the products listed above, or may be implemented in other forms. This embodiment of the present application does not impose strict limitations on the application of energy storage device 440. This embodiment of the present application uses a multi-cell battery as an example for illustration.

[0063] Optionally, when the energy storage device 440 is a single battery, the energy storage device 440 may be, but is not limited to, at least one of a cylindrical battery, a square battery, a prismatic battery, or batteries of other shapes.

[0064] See Figures 4 to 8 The present application provides an electrode assembly 100, which includes a negative electrode plate 110, a separator 120 and a positive electrode plate 130. The separator 120 is arranged on one side of the negative electrode plate 110, and the separator 120 includes a base film 121 and a glue layer 122. The glue layer 122 is arranged on at least one side of the base film 121, and the glue layer 122 includes a first polymer, which is a polymer having one of an ester bond and an epoxy bond; the positive electrode plate 130 is arranged on the side of the separator 120 where the glue layer 122 is provided; the positive electrode plate 130 includes an active material layer 131, and the active material layer 131 includes a second polymer, which is a polymer having an amino group and a hydroxyl group.

[0065] It can be understood that the negative electrode sheet 110 , the separator 120 , and the positive electrode sheet 130 are stacked and then wound to form the electrode assembly 100 .

[0066] Optionally, the base film 121 is selected from one of a polyethylene film and a polypropylene film.

[0067] Optionally, in one embodiment, when the diaphragm 120 is the polyethylene film, the diaphragm 120 further includes a ceramic coating 123, which is located between the base film 121 and the adhesive layer 122 to improve the thermal stability and mechanical strength of the diaphragm 120. In another embodiment, when the diaphragm 120 is the polypropylene film, the adhesive layer 122 is provided on the surface of the base film 121.

[0068] It can be understood that the glue layer 122 of the separator 120 is arranged opposite to the active material layer 131 of the positive electrode plate 130 to achieve adhesion with the active material layer 131 .

[0069] It can be understood that the electrode assembly 100 is applied to a battery 200 .

[0070] It can be understood that the first polymer is a polymer having one of a urethane bond and an epoxy bond. In some embodiments, the first polymer is a polymer having a urethane bond; in other embodiments, the first polymer is a polymer having an epoxy bond.

[0071] It is understandable that in this application Figure 4 In the embodiment, the positive electrode sheet 130, the separator 120 and the negative electrode sheet 110 are stacked and wound to form a winding structure; Figure 5 In the embodiment, the positive electrode sheet 130 , the separator 120 and the negative electrode sheet 110 are stacked.

[0072] In this embodiment, the negative electrode sheet 110, the separator 120, and the positive electrode sheet 130 are stacked, wound, and pressed to form the electrode assembly 100. The positive electrode sheet 130 is disposed on the side of the separator 120 where the glue layer 122 is disposed. In other words, the active material layer 131 of the positive electrode sheet 130 is disposed opposite the glue layer 122. The glue layer 122 includes a first polymer, and the active material layer 131 includes a second polymer, wherein the second polymer is a polymer having amino and hydroxyl groups. When the first polymer is a polymer having urethane bonds, the urethane bonds contain strongly electronegative oxygen and nitrogen atoms. The hydrogen atoms in the amino and hydroxyl groups of the second polymer can interact with the charges of the nitrogen or oxygen atoms in the urethane bonds to form hydrogen bonds, thereby improving the interfacial adsorption between the glue layer 122 and the active material layer 131. Similarly, when the first polymer is a polymer having epoxy bonds, the amino and hydroxyl groups in the second polymer can form hydrogen bonds with the oxygen atoms in the epoxy groups. This intermolecular force can enhance the compatibility and adhesion between the first and second polymers, thereby improving the interfacial adsorption between the glue layer 122 and the active material layer 131. During the pressing process of the electrode assembly 100, since the first and second polymers can form hydrogen bonds and enhance the interfacial adsorption between the glue layer 122 and the active material layer 131, specifically, within the inner coil of the wound structure formed by the positive electrode sheet 130, the separator 120, and the negative electrode sheet 110, the positive electrode sheet 130 and the separator 120 have good bonding strength and conformity. This allows the electrode assembly 100 to achieve high bonding between the glue layer 122 and the active material layer 131 even at room temperature and under low-pressure pressing conditions, thereby improving the manufacturing performance of the electrode assembly 100. Specifically, the electrode assembly 100 can produce better bonding under lower or moderate pressure, avoiding damage to the structure of the base membrane 121 under high pressure, and avoiding changes in the porosity and tortuosity of the positive electrode plate 130 and / or the negative electrode plate 110, so as to avoid destroying the ion transmission path and affecting the ion transmission capacity of the diaphragm 120. When the electrode assembly 100 is applied to the battery 200, the battery 200 has better charge and discharge performance and cycle stability.

[0073] It can be understood that the electrode assembly 100 provided in the present application can produce better bonding under lower or moderate pressure, which can avoid the pressure difference between the inner and outer circles of the electrode assembly 100 being too large, resulting in the bonding strength of the inner circle being too weak. In other words, the diaphragm 120 and the positive electrode plate 130 have a higher bonding strength. When the electrode assembly 100 is applied to the battery 200 and is infiltrated by the electrolyte 210, the diaphragm 120 locally bulges or shrinks under the capillary action when the electrolyte 210 is infiltrated. The positive electrode plate 130 can constrain the diaphragm 120 to avoid deformation of the diaphragm 120, thereby avoiding the diaphragm 120 squeezing the negative electrode plate 110, and ultimately avoiding the interface wrinkles of the negative electrode plate 110 of the inner circle when the electrode assembly 100 is applied to the battery 200 and after charge and discharge cycles, reducing the risk of purple spots and lithium precipitation, which is beneficial to improving the performance of the electrode assembly 100 and the cycle performance of the battery 200.

[0074] Optionally, in a specific embodiment, the adhesive layer 122 further comprises polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylic acid, and acrylic resin emulsion as adhesives to bond the positive electrode plate 130. The use of polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylic acid, and acrylic resin emulsion as adhesives commonly used for the adhesive layer 122 is merely illustrative and should not be construed as limiting the choice of adhesive for the adhesive layer 122.

[0075] Optionally, the active material layer 131 further includes active particles, and the active particles are selected from at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium iron phosphate, and lithium nickel cobalt aluminum oxide.

[0076] In some embodiments, the first polymer includes one of polyurethane, amino acrylic resin, epoxy resin, and epoxy acrylate; the second polymer includes one of polydopamine, a polydopamine derivative, a copolymer containing dopamine, and chitosan.

[0077] It can be understood that polyurethane and amino acrylic resin are polymers having urethane bonds, and epoxy resin and epoxy acrylate are polymers having epoxy bonds.

[0078] In this embodiment, the first polymer includes one of polyurethane, amino acrylic resin, epoxy resin, and epoxy acrylate, and the second polymer includes one of polydopamine, a polydopamine derivative, a copolymer containing dopamine, and chitosan. Compared with other polymers that can form hydrogen bonds, the hydrogen bonds formed by the first polymer and the second polymer are more stable, which is beneficial to maintaining the interfacial adsorption between the glue layer 122 and the active material layer 131. In addition, the selection cost of the first polymer and the second polymer is low, and they have good resistance to the electrolyte 210, which is beneficial to improving the performance of the battery 200. Furthermore, polydopamine, polydopamine derivatives, copolymers containing dopamine, and chitosan have good adhesion properties. When polydopamine, polydopamine derivatives, copolymers containing dopamine, and chitosan are applied to the active material layer 131, they can also improve the adhesion to the active particles in the active material layer 131, which can improve the cohesion of the positive electrode sheet 130.

[0079] As you can understand, polyurethane (PU) is a polymer compound produced by the polymerization reaction of diisocyanates or polyisocyanates with diols, triols, or water, containing repeating carbamate groups in the backbone. Conventional polyurethane can be dissolved in the organic solvent NMP. If the solvent is water, a water-based polyurethane must be used. (Water-based polyurethane is insoluble in water and is a novel polyurethane system that uses water instead of organic solvents as the dispersion medium. It is also called water-dispersible polyurethane, water-based polyurethane, or water-based polyurethane.)

[0080] Understandably, polydopamine (PDA) refers to a biomimetic polymer with a structure similar to dopamine in marine mussel adhesive proteins. Dopamine, whose scientific name is 4-(2-aminoethyl)-1,2-diol, the catechol group of dopamine is easily oxidized to form polydopamine containing amino, hydroxyl and benzene ring structures. Polydopamine has photothermal conversion, biomimetic adhesion and antioxidant properties, and has broad application prospects in coating materials, electronics, biomedicine, energy storage and other fields. Polydopamine contains a large number of phenolic hydroxyl and amino functional groups, and can adhere to the surfaces of materials such as glass, stainless steel, plastic, rubber, polytetrafluoroethylene, etc., and has excellent adhesion properties.

[0081] Polydopamine is soluble in NMP (N-methylpyrrolidone) and can be added as a binder to the positive electrode slurry and coated on the surface of the active particles of the active material layer 131 to improve the cycle performance. The amino or hydroxyl groups on the surface of polydopamine may react with the ester group or double bond in the acrylate to form a covalent bond. The PDA coating can also provide higher surface energy and produce a conjugated effect on the liquid electrolyte, thereby constructing a smoother ion transmission channel, reducing the risk of leakage of the liquid electrolyte, and reducing side reactions caused at the interface. Polydopamine is insoluble in water and therefore cannot be used in negative electrode slurry.

[0082] Optionally, during the preparation of the adhesive layer 122, the first polymer is dispersed in water and mixed with other substances such as polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylic acid and acrylic resin emulsion in a certain proportion and fully stirred to form a solution of the adhesive layer 122, which is then coated on the surface of the base film 121 or the ceramic coating 123, and the adhesive layer 122 is obtained after drying to remove moisture.

[0083] In other words, the raw material of the first polymer is selected from one of water-based polyurethane, water-based amino acrylic resin, water-based bisphenol A epoxy resin emulsion, water-based epoxy acrylate emulsion, water-based glycidyl ester epoxy resin, and water-based glycidyl ether epoxy resin emulsion, so that the first polymer can be evenly mixed with other substances in the adhesive layer 122, thereby improving the uniformity of the adhesive layer 122 and allowing the first polymer to play a role in forming hydrogen bonds with the second polymer.

[0084] Optionally, the viscosity of the dispersion formed by dispersing the first polymer in water is in the range of 100 mPa·s to 300 mPa·s, so that the first polymer is fully mixed with other substances in the adhesive layer 122, so that the adhesive layer 122 has good uniformity after drying.

[0085] Specifically, the viscosity of the dispersion formed by dispersing the first polymer in water can be, but is not limited to, 100 mPa·s, 110 mPa·s, 125 mPa·s, 135 mPa·s, 150 mPa·s, 165 mPa·s, 188 mPa·s, 200 mPa·s, 220 mPa·s, 235 mPa·s, 240 mPa·s, 255 mPa·s, 265 mPa·s, 280 mPa·s, 0.85 mPa·s, 298 mPa·s and 300 mPa·s, etc.

[0086] Optionally, the median particle size of the first polymer is in a range of 40 nm to 200 nm, so that the first polymer and the second polymer can contact and form hydrogen bonds.

[0087] It can be understood that the median particle size of the first polymer is determined by referring to the test method of the standard "GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method", and a laser particle size analyzer is used to test the particle size of the first polymer to obtain the median particle size data.

[0088] Specifically, the median particle size of the first polymer may be, but is not limited to, 40 nm, 50 nm, 65 nm, 80 nm, 85 nm, 95 nm, 100 nm, 105 nm, 115 nm, 135 nm, 150 nm, 165 nm, 180 nm, 184 nm, 190 nm, and 200 nm.

[0089] Optionally, the solid content of the dispersion formed by dispersing the first polymer in water is in the range of 40% to 60%. In other words, the mass proportion of the first polymer in the dispersion is 40% to 60%, so that the viscosity of the dispersion is within a reasonable range, which facilitates the full mixing and dispersion of the first polymer and other components in the adhesive layer 122.

[0090] Specifically, the solid content of the dispersion formed by dispersing the first polymer in water can be, but is not limited to, 40%, 42%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 58%, 59% and 60%.

[0091] Optionally, the adhesive layer 122 is provided on one side of the base film 121 by at least one of rotary spraying, roller coating, and jet coating.

[0092] Optionally, when the adhesive layer 122 is applied to one side of the base film 121 by roller coating or spray coating, the adhesive layer 122 is a dot matrix adhesive layer 122. When the adhesive layer 122 is applied to one side of the base film 121 by rotary spray coating, the adhesive layer 122 is formed by a plurality of irregularly shaped adhesive dots, and the plurality of adhesive dots are at least partially connected.

[0093] It can be understood that the glue layer 122 is composed of multiple glue dots, and the multiple glue dots are at least partially connected. The shape of the positive projection of the glue dots on the base film 121 can be but is not limited to a circle, a quasi-circle, and an irregular shape.

[0094] Optionally, the single-sided surface density of the adhesive layer 122 is in the range of 0.3 g / m 2 Up to 0.8g / m 2, so that when the electrode assembly 100 is pressed, the glue layer 122 and the active material layer 131 have a sufficiently large contact area, and further the first polymer and the second polymer have a sufficiently large contact area, so that the first polymer and the second polymer form hydrogen bonds, thereby improving the interfacial adsorption force between the glue layer 122 and the active material layer 131.

[0095] Specifically, the single-surface density of the adhesive layer 122 may be, but is not limited to, 0.3 g / m 2 , 0.35g / m 2 , 0.4g / m 2 , 0.45g / m 2 , 0.5g / m 2 , 0.55g / m 2 , 0.58g / m 2 , 0.6g / m 2 , 0.65g / m 2 , 0.7g / m 2 , 0.73g / m 2 , 0.75g / m 2 and 0.8g / m 2 wait.

[0096] Optionally, the radial size of the glue dots is within a range of 200 μm to 800 μm, so that the first polymer and the second polymer can contact and form hydrogen bonds, thereby enhancing the interfacial adsorption force between the separator 120 and the positive electrode plate 130 .

[0097] It can be understood that when the shape of the orthographic projection of the glue dot on the base film 121 is a circle, the radial dimension of the glue dot is the diameter of the circle.

[0098] Specifically, the radial dimension of the glue dot may be, but is not limited to, 200 μm, 220 μm, 250 μm, 300 μm, 320 μm, 380 μm, 400 μm, 450 μm, 500 μm, 525 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, and 800 μm.

[0099] Optionally, the ionic conductivity of the membrane 120 is in the range of 1.2 mS / cm≤σ≤1.7 mS / cm. When the first polymer is added to the glue layer 122 , the membrane 120 still has a relatively high ionic conductivity, thereby avoiding affecting ion transmission due to the addition of the first polymer.

[0100] It can be understood that the electrode assembly 100 includes at least one of the following features: the mass ratio q1 of the first polymer to the second polymer satisfies the range of 10 / 3 ≤ q1 ≤ 100; the weight average molecular weight M1 of the first polymer satisfies the range of 800 ≤ M1 ≤ 30,000; and the weight average molecular weight M2 of the second polymer satisfies the range of 2,000 ≤ M2 ≤ 200,000. In the electrode assembly 100 provided herein, the first polymer and the second polymer satisfy one or more of the above conditions.

[0101] In some embodiments, the mass ratio q1 of the first polymer to the second polymer satisfies the range: 10 / 3≤q1≤100.

[0102] It can be understood that q1 is the ratio of the mass of the first polymer to the mass of the second polymer.

[0103] Specifically, the mass ratio q1 of the first polymer to the second polymer can be, but is not limited to, 10 / 3, 4, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 45, 48, 50, 55, 58, 60, 62, 65, 68, 70, 75, 78, 85, 88, 90, 95, 98 and 100, etc.

[0104] In this embodiment, when the mass ratio q1 of the first polymer to the second polymer satisfies the range of 10 / 3 ≤ q1 ≤ 100, the mass ratio of the first polymer to the second polymer is within a reasonable range. On the one hand, during the pressing process of the electrode assembly 100, the first polymer and the second polymer interact to form hydrogen bonds, thereby improving the interfacial adsorption between the glue layer 122 and the active material layer 131, thereby enabling the electrode assembly 100 to achieve high adhesion performance at room temperature and low pressure. On the other hand, this prevents the first polymer from occupying an excessive amount of the glue layer 122 and affecting the adhesion of the glue layer 122 to the positive electrode sheet 130, and also prevents the second polymer from occupying an excessive amount of the active material layer 131 and affecting the capacity of the positive electrode sheet 130. When the value of q1 is too large, the mass of the first polymer is much greater than that of the second polymer, resulting in either an excessive amount of the first polymer or an excessive amount of the second polymer. Excessive amounts of the first polymer may reduce the mass percentage of other components in the glue layer 122, such as the binder, weakening the adhesive properties of the glue layer 122 to the positive electrode tab 130. When the content of the second polymer is too small, the hydrogen bonds formed by the interaction between the first and second polymers are too few, hindering improved interfacial adsorption between the positive electrode tab 130 and the separator 120, and thus hindering improved adhesion between the two. When the value of q1 is too small, the mass of the first polymer is much less than that of the second polymer, resulting in either an excessive amount of the first polymer or an excessive amount of the second polymer. Excessive amounts of the first polymer may result in a decrease in the hydrogen bonds formed by the interaction between the first and second polymers, hindering improved interfacial adsorption between the positive electrode tab 130 and the separator 120, and thus hindering improved adhesion between the two. When the content of the second polymer is too high, the mass percentage of other components in the active material layer 131, such as active particles, is reduced accordingly, thereby reducing the capacity of the positive electrode sheet 130 and the energy density of the battery 200 when the electrode assembly 100 is applied to the battery 200.

[0105] In some embodiments, the weight average molecular weight M1 of the first polymer satisfies the range: 800≤M1≤30000.

[0106] Specifically, the weight average molecular weight M1 of the first polymer can be, but is not limited to, 800, 1000, 2500, 5000, 6000, 8000, 10000, 15000, 30000, 45000, 65000, 88000, 100000, 135000, 155000, 185000, 220000, 235000, 250000, 280000 and 300000, etc.

[0107] In this embodiment, when the weight-average molecular weight M1 of the first polymer satisfies the range of 8000 ≤ M1 ≤ 300,000, the weight-average molecular weight of the first polymer is within a reasonable range, facilitating the dispersion of the first polymer in water. Furthermore, during the preparation of the solution for the gel layer 122, the first polymer is facilitated to mix evenly with other substances in the gel layer 122, such as an adhesive, thereby improving the uniformity of the gel layer 122, facilitating the gel layer 122 to bond to the positive electrode sheet 130, and enhancing the performance and manufacturing properties of the electrode assembly 100. When the weight-average molecular weight of the first polymer is too large, although the number of intermolecular hydrogen bonds formed between the first polymer and the second polymer increases, strengthening the intermolecular forces and improving the crystallinity, such as increasing hardness, strength, and viscosity, as the weight-average molecular weight of the first polymer increases, uniform dispersion of the first polymer becomes more difficult, requiring longer stirring times and higher rotation speeds, and increasing the difficulty of preparation. When the weight average molecular weight of the first polymer is too small, the number of intermolecular hydrogen bonds will be reduced, resulting in poor viscosity and strength between the adhesive layer 122 and the positive electrode plate 130 , and poor temperature resistance of the adhesive layer 122 .

[0108] In some embodiments, the weight average molecular weight M2 of the second polymer satisfies the range: 2000≤M2≤200000.

[0109] Specifically, the weight average molecular weight M2 of the second polymer may be, but is not limited to, 2000, 10000, 25000, 50000, 66000, 80000, 100000, 120000, 150000, 160000, 180000 and 200000, etc.

[0110] In this embodiment, when the weight-average molecular weight M2 of the second polymer satisfies the range of 2000 ≤ M2 ≤ 200,000, the weight-average molecular weight of the second polymer is within a reasonable range, facilitating dispersion of the second polymer in the active material layer 131. Furthermore, the second polymer contains a relatively large number of amino and hydroxyl groups, and the chains are not entangled due to an excessively high weight-average molecular weight, thereby increasing the probability of hydrogen bonding between the second polymer and the first polymer, thereby enhancing the interfacial adsorption between the glue layer 122 and the active material layer 131. When the weight-average molecular weight of the second polymer is too large, although the second polymer contains a relatively large number of amino and hydroxyl groups, the larger the weight-average molecular weight, the more likely the second polymer chains are to be entangled, resulting in some amino and hydroxyl groups being encapsulated in the entangled structure, reducing the probability of amino and hydroxyl groups combining with the epoxy bonds of the first polymer and forming hydrogen bonds, which in turn is detrimental to enhancing the interfacial adsorption between the glue layer 122 and the positive electrode sheet 130. When the weight-average molecular weight of the second polymer is too small, the number of amino groups and hydroxyl groups in the second polymer is limited, which reduces the hydrogen bonds formed between the second polymer and the first polymer. It is also difficult for the first polymer and the second polymer to enhance the interfacial adsorption force between the glue layer 122 and the active material layer 131, which is not conducive to improving the preparation performance of the electrode assembly 100.

[0111] It is understood that the electrode assembly 100 includes at least one of the following features: in the glue layer 122, the mass percentage a1 of the first polymer is in the range of 0.5% ≤ a1 ≤ 5%; and in the active material layer 131, the mass percentage a2 of the second polymer is in the range of 0.1% ≤ a2 ≤ 2%. In the electrode assembly 100 provided in this application, the mass percentage a1 of the first polymer satisfies the range of 0.5% ≤ a1 ≤ 5% and / or the mass percentage a2 of the second polymer satisfies the range of 0.1% ≤ a2 ≤ 2%.

[0112] In some embodiments, in the adhesive layer 122 , the mass percentage a1 of the first polymer is in the range of 0.5%≤a1≤5%.

[0113] It can be understood that the mass percentage of the first polymer is the ratio of the mass of the first polymer to the mass of the adhesive layer 122 .

[0114] Specifically, in the adhesive layer 122, the mass percentage a1 of the first polymer can be, but is not limited to, 0.5%, 0.8%, 1%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8% and 5%, etc.

[0115] In the glue layer 122 provided in this embodiment, when the mass percentage a1 of the first polymer satisfies the range of 0.5% ≤ a1 ≤ 5%, the mass percentage of the first polymer is within a reasonable range. The first polymer can form a large number of hydrogen bonds with the second polymer, thereby enhancing the interfacial adsorption between the glue layer 122 and the positive electrode tab 130 and reducing the pressure required to press the electrode assembly 100. Furthermore, the mass percentages of other substances in the glue layer 122, such as the adhesive, are also within a reasonable range, ensuring the adhesion of the separator 120 to the positive electrode tab 130, thereby enabling the electrode assembly 100 to have both good manufacturing and performance. When the mass percentage a1 of the first polymer is too large, the mass percentages of other components in the glue layer 122, such as the adhesive, decrease, weakening the adhesion of the glue layer 122 to the positive electrode tab 130. When the mass percentage a1 of the first polymer is too low, fewer hydrogen bonds are formed between the first polymer and the second polymer, making it difficult for the first polymer and the second polymer to enhance the interfacial adsorption between the glue layer 122 and the positive electrode tab 130. Consequently, during the pressing process of the electrode assembly 100, at relatively low or moderate pressures, the adhesion between the separator 120 and the positive electrode tab 130 may be weak. Increasing the pressing pressure to ensure adhesion may damage the structure of the base film 121 of the separator 120, thereby affecting the ion transport performance of the separator 120 and ultimately the performance of the electrode assembly 100.

[0116] In some embodiments, in the active material layer 131 , the mass percentage a2 of the second polymer is in the range of 0.1%≤a2≤2%.

[0117] It can be understood that the mass percentage of the second polymer is the ratio of the mass of the second polymer to the mass of the active material layer 131 .

[0118] Specifically, in the active material layer 131 , the mass percentage a2 of the second polymer may be, but is not limited to, 0.1%, 0.2%, 0.4%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.6%, 1.8% and 2%, etc.

[0119] In the active material layer 131 provided in this embodiment, when the mass percentage a2 of the second polymer satisfies the range of 0.1% ≤ a2 ≤ 2%, the mass percentage of the second polymer is within a reasonable range. During the pressing process of the electrode assembly 100, the second polymer and the first polymer can form sufficient hydrogen bonds to enhance the interfacial adsorption between the glue layer 122 and the active material layer 131, thereby reducing the pressure during the pressing of the electrode assembly 100 and preventing damage to the base film 121 structure caused by excessive pressing pressure. Furthermore, the mass percentage of other substances in the active material layer 131, such as the active particles, is also within a reasonable range, ensuring a high capacity of the positive electrode sheet 130, thereby enabling the electrode assembly 100 to have both good manufacturing and performance. When the mass percentage of the second polymer is too high, the mass percentage of other components in the active material layer 131, such as the active particles, is correspondingly reduced, reducing the capacity of the positive electrode sheet 130 and the energy density of the battery 200 when the electrode assembly 100 is used. When the mass percentage of the second polymer is too low, fewer hydrogen bonds are formed between the first polymer and the second polymer during the pressing process of the electrode assembly 100, resulting in a weak interfacial adsorption force between the glue layer 122 and the positive electrode sheet 130, making it difficult to improve the bonding performance between the separator 120 and the positive electrode sheet 130. During the pressing process of the electrode assembly 100, under low or moderate pressure, the bonding performance between the separator 120 and the positive electrode sheet 130 may be weak. If the pressing pressure is increased to ensure bonding performance, the structure of the base film 121 of the separator 120 may be damaged, thereby affecting the ion transmission performance of the separator 120 and ultimately affecting the performance of the electrode assembly 100.

[0120] In some embodiments, the adhesive layer 122 further includes a surfactant, and the surfactant is selected from at least one of polyvinyl alcohol, epoxysilane hydroxyl, ethyl cellulose, fatty acid ester, carboxylic acid ester, lactic acid ester, and cellulose ester.

[0121] It can be understood that during the preparation of the adhesive layer 122, the surfactant is dispersed in water and mixed with other substances such as the first polymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylic acid and acrylic resin emulsion in a certain proportion and fully stirred to form a solution of the adhesive layer 122, which is then coated on the surface of the base film 121 or the ceramic coating 123, and the adhesive layer 122 is obtained after removing the moisture by drying.

[0122] In this embodiment, the adhesive layer 122 further includes a surfactant selected from at least one of polyvinyl alcohol, epoxysilane hydroxyl, ethyl cellulose, fatty acid esters, carboxylic acid esters, lactic acid esters, and cellulose esters. During the preparation of the solution for the adhesive layer 122, the surfactant is dispersed in water to increase the surface tension of the solution of the adhesive layer 122. When the adhesive layer 122 is disposed on one side of the base film 121, the surfactant can enhance the coffee ring effect, causing the adhesive dots applied on one side of the base film 121 to form a crater morphology. It also helps increase the height of the adhesive dots protruding from the base film 121, thereby increasing the contact area between the adhesive layer 122 and the active material layer 131 after the electrode assembly 100 is rolled. This, to a certain extent, helps promote the formation of hydrogen bonds between the first polymer and the second polymer, thereby improving the adhesion between the adhesive layer 122 and the active material layer 131.

[0123] It can be understood that in some specific embodiments, the surfactant is a new type of water-based coupling agent. This type of coupling agent achieves better solubility by introducing new functional groups or changing the molecular structure. For example, by introducing fatty acid chains, the water solubility of the coupling agent can be significantly improved; by introducing alkyl or amide groups, the water-based and adhesion properties of the coupling agent can be significantly enhanced. Fatty acid esters and carboxylic acid esters are common new water-based coupling agents.

[0124] In some embodiments, the mass ratio q2 of the first polymer to the surfactant satisfies the range: 5≤q2≤50.

[0125] Specifically, the mass ratio q2 of the first polymer to the surfactant can be, but is not limited to, 5, 8, 9, 10, 12, 15, 18, 20, 25, 28, 30, 33, 35, 36, 38, 40, 43, 44, 46, 48 and 50, etc.

[0126] In this embodiment, when the mass ratio q2 of the first polymer to the surfactant satisfies the range of 5≤q2≤50, the mass of the first polymer and the mass of the surfactant are both within a reasonable range. The surfactant can increase the contact area and degree of adhesion between the first polymer and the second polymer, allowing the first polymer and the second polymer to form more hydrogen bonds and ensuring sufficient adhesion between the glue layer 122 and the active material layer 131. This improves the adhesion between the separator 120 and the positive electrode plate 130, thereby enhancing the manufacturing and performance of the electrode assembly 100. When the value of q2 is too large, the mass of the first polymer is too high or the mass of the surfactant is too low. If the mass of the first polymer is too high, the mass percentage of other components in the glue layer 122, such as the binder, is reduced, weakening the adhesion of the glue layer 122 to the positive electrode plate 130. If the surfactant mass is too low, its ability to increase the surface tension of the solution in the adhesive layer 122 is weakened. When the adhesive layer 122 is positioned on one side of the base film 121, it becomes difficult to form a crater-shaped adhesive point. This makes it difficult to increase the contact area between the first polymer and the second polymer, weakening the surfactant's ability to promote hydrogen bonding between the first and second polymers. This results in poor adhesion between the adhesive layer 122 and the positive electrode tab 130. If the value of q2 is too low, the mass of the first polymer is too low or the mass of the surfactant is too high. If the mass of the first polymer is too low, fewer hydrogen bonds are formed between the first and second polymers, making it difficult for the first and second polymers to enhance the interfacial adsorption between the adhesive layer 122 and the positive electrode tab 130. If the mass of the surfactant is too high, the raw material cost of the adhesive layer 122 increases, and during the preparation process of the solution for the adhesive layer 122, the viscosity of the solution increases, resulting in poor dispersion of other substances in the adhesive layer 122 and affecting the uniformity of the adhesive layer 122.

[0127] In some embodiments, in the adhesive layer 122 , the mass percentage a3 of the surfactant is in the range of 0.1%≤a3≤2%.

[0128] It can be understood that the mass percentage a3 of the surfactant is the ratio of the mass of the surfactant to the mass of the adhesive layer 122 .

[0129] Specifically, in the adhesive layer 122 , the mass percentage a3 of the surfactant may be, but is not limited to, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8% and 2%.

[0130] In the adhesive layer 122 provided in this embodiment, when the mass percentage a3 of the surfactant satisfies the range of 0.1% ≤ a3 ≤ 2%, the mass percentage of the surfactant is within a reasonable range. The surfactant increases the surface tension of the solution of the adhesive layer 122, resulting in a greater height of the adhesive dots applied to the base film 121 when the adhesive layer 122 is disposed on one side of the base film 121. This increases the contact area between the adhesive layer 122 and the active material layer 131 after further rolling, facilitating full contact and formation of more hydrogen bonds between the first polymer and the second polymer, ultimately improving the adhesion between the adhesive layer 122 and the active material layer 131. If the mass percentage a3 of the surfactant is too high, the raw material cost of the adhesive layer 122 will increase, and during the preparation process of the solution of the adhesive layer 122, the viscosity of the solution of the adhesive layer 122 will increase, resulting in poor dispersion of other substances in the adhesive layer 122 and affecting the uniformity of the adhesive layer 122. When the mass percentage a3 of the surfactant is too small, the effect of the surfactant in increasing the surface tension of the solution of the glue layer 122 is weakened. When the glue layer 122 is arranged on one side of the base film 121, it is difficult to form a glue point with a crater morphology, thereby making it difficult to increase the contact area between the first polymer and the second polymer, weakening the effect of the surfactant in promoting the formation of hydrogen bonds between the first polymer and the second polymer, thereby making the degree of adhesion between the glue layer 122 and the positive electrode plate 130 poor.

[0131] In some embodiments, the negative electrode plate 110, the separator 120 and the positive electrode plate 130 are stacked and then wound to form a wound structure. The electrode assembly 100 is pressed for 40 seconds at room temperature. The unit area pressure of the separator 120 is P. In the innermost circle of the wound structure, the peeling strength between the separator 120 and the positive electrode plate 130 is Q. The coverage of the adhesive layer 122 on the base film 121 is S. Then, the electrode assembly 100 satisfies the relationship: 0≤(SP×Q)≤20.

[0132] Specifically, the value of (SP×Q) can be, but is not limited to, 0, 1, 2, 3, 5, 8, 10, 12, 14, 15, 18, 19, and 20.

[0133] In this embodiment, when the electrode assembly 100 satisfies the relationship 0≤(SP×Q)≤20, the coverage S of the base film 121 by the glue layer 122, the pressure per unit area P of the separator 120, and the peel strength Q between the separator 120 and the positive electrode tab 130 are interrelated to regulate the performance of the electrode assembly 100. Specifically, the coverage S of the base film 121 by the glue layer 122 and the pressure per unit area Q of the separator 120 have a synergistic effect to avoid insufficient pressure or uneven distribution of the glue layer 122, which may result in a low peel strength between the separator 120 and the positive electrode tab 130. Furthermore, the glue layer 122 may be prevented from excessively covering the base film 121 or from damaging the base film 121 of the separator 120 or affecting the transmission of ion conduction due to excessive pressing pressure. When the electrode assembly 100 satisfies the relationship 0≤(SP×Q)≤20, the electrode assembly 100 can maintain the ion transmission performance of the diaphragm 120 while ensuring the bonding force between the positive electrode plate 130 and the diaphragm 120, so that when the electrode assembly 100 is applied to the battery 200, the battery 200 has better charge and discharge efficiency.

[0134] It can be understood that the electrode assembly 100 includes at least one of the following features: the coverage S of the adhesive layer 122 on the base film 121 is in the range of 5% ≤ S ≤ 30%; the pressure per unit area P of the separator 120 when the electrode assembly 100 is pressed for 40 seconds at room temperature is in the range of 2.8 MPa ≤ P ≤ 4.8 MPa; and the peel strength Q between the separator 120 and the positive electrode sheet 130 in the innermost coil of the wound structure is in the range of 1.5 N / m ≤ Q ≤ 5 N / m. In the electrode assembly 100 provided in this application, at least one of S, P, and Q satisfies the above numerical ranges.

[0135] In some embodiments, the coverage S of the adhesive layer 122 to the base film 121 is in the range of 5%≤S≤30%.

[0136] Specifically, the coverage S of the adhesive layer 122 to the base film 121 can be, but is not limited to, 5%, 6%, 8%, 10%, 12%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 28% and 30%, etc.

[0137] In this embodiment, when the coverage S of the glue layer 122 on the base film 121 satisfies the range of 5%≤S≤30%, the coverage S of the glue layer 122 on the base film 121 is within a reasonable range. On the one hand, during the pressing process of the electrode assembly 100, the glue layer 122 can effectively bond to the active material layer 131, and the first polymer and the second polymer have sufficient contact area and form hydrogen bonds to increase the degree of fit between the diaphragm 120 and the positive electrode sheet 130. The electrode assembly 100 can produce better bonding under lower or moderate pressure, avoiding damage to the structure of the base film 121 under high pressure, and avoiding changes in the porosity and tortuosity of the positive electrode sheet 130 and / or the negative electrode sheet 110, so as to avoid destroying the ion transmission path and affecting the ion transmission capacity of the diaphragm 120. When the electrode assembly 100 is applied to the battery 200, the battery 200 has good charge and discharge performance and cycle stability. On the other hand, the glue layer 122 can be prevented from blocking the pores of the base film 121 and affecting the ion transmission efficiency, thereby ensuring the energy efficiency of the battery 200. When the coverage S of the glue layer 122 on the base film 121 is too large, the glue layer 122 may block the pores of the base film 121, thereby hindering the transmission of lithium ions on the separator 120. When the electrode assembly 100 is used in the battery 200, it will affect the energy efficiency of the battery 200. Furthermore, the greater the coverage of the glue layer 122, the higher the raw material cost of the glue layer 122. When the coverage rate S of the glue layer 122 on the base film 121 is too small, the adhesion between the glue layer 122 and the base film 121 is still poor during the pressing process of the electrode assembly 100. This makes it difficult for the positive electrode sheet 130 and the separator 120 to adhere to each other in the inner circle of the wound structure formed by the positive electrode sheet 130, the separator 120, and the negative electrode sheet 110. The negative electrode sheet 110 is prone to wrinkles or purple spots, which reduces the performance of the electrode assembly 100. Moreover, when the electrode assembly 100 is used in the battery 200, the cycle performance of the battery 200 is poor.

[0138] In some embodiments, the electrode assembly 100 is pressed for 40 seconds at room temperature, and the pressure per unit area P of the separator 120 is in the range of 2.8 MPa≤P≤4.8 MPa.

[0139] Specifically, the value of the unit area pressure P of the diaphragm 120 can be, but is not limited to, 2.8 MPa, 3 MPa, 3.2 MPa, 3.5 MPa, 3.8 MPa, 4 MPa, 4.2 MPa, 4.5 MPa, 4.6 MPa, 4.7 MPa, and 4.8 MPa.

[0140] In this embodiment, when the electrode assembly 100 is pressed for 40 seconds at room temperature, the unit area pressure P of the diaphragm 120 satisfies the range of 2.8MPa≤P≤4.8MPa, and the unit area pressure of the diaphragm 120 is relatively small. In other words, during the pressing process of the electrode assembly 100, the electrode assembly 100 can produce better adhesion under a lower or moderate pressure, avoiding damage to the structure of the base membrane 121 under high pressure, and avoiding changes in the porosity and tortuosity of the positive electrode sheet 130 and / or the negative electrode sheet 110, so as to avoid destroying the ion transmission path and affecting the ion transmission capacity of the diaphragm 120. When the electrode assembly 100 is applied to the battery 200, the battery 200 has good charge and discharge performance and cycle stability.

[0141] In some embodiments, in the innermost circle of the winding structure, the peel strength Q between the separator 120 and the positive electrode sheet 130 is in the range of 1.5 N / m≤Q≤5 N / m.

[0142] Specifically, the peel strength Q between the diaphragm 120 and the positive electrode plate 130 may be, but is not limited to, 1.5 N / m, 1.8 N / m, 2 N / m, 2.2 N / m, 2.5 N / m, 2.8 N / m, 3 N / m, 3.2 N / m, 3.5 N / m, 3.8 N / m, 4 N / m, 4.2 N / m, 4.5 N / m, 4.8 N / m and 5 N / m, etc.

[0143] It can be understood that in the winding structure formed by the positive electrode sheet 130, the diaphragm 120 and the negative electrode sheet 110, the peeling strength between the innermost circle of the diaphragm 120 and the positive electrode sheet 130 is the smallest. In other words, from the center of the winding structure to the outside, the peeling strength between the diaphragm 120 and the positive electrode sheet 130 gradually increases.

[0144] In this embodiment, when the peel strength Q between the separator 120 and the positive electrode sheet 130 in the innermost coil of the wound structure satisfies the range of 1.5 N / m ≤ Q ≤ 5 N / m, the separator 120 and the positive electrode sheet 130 still maintain a relatively high peel strength under room temperature pressing and relatively low pressure pressing conditions. When the electrode assembly 100 is used in the battery 200 and undergoes charge and discharge cycles, the separator 120 and the positive electrode sheet 130 maintain a relatively good bond strength, thereby preventing wrinkles at the interface of the negative electrode sheet 110 and reducing the risk of purple spots and lithium deposition, thereby improving the performance of the electrode assembly 100 and the cycle performance of the battery 200.

[0145] Optionally, the positive electrode plate 130 further includes a positive current collector layer 132 , and the active material layer 131 is disposed on at least one side of the positive current collector layer 132 . The positive current collector layer 132 is used to support the active material layer 131 and quickly transmit electrons generated by the active material layer 131 to the outside.

[0146] Optionally, the single-sided coating thickness of the active material layer 131 ranges from 60μm to 120μm. Specifically, the single-sided coating thickness of the active material layer 131 can be, but is not limited to, 60μm, 62μm, 65μm, 70μm, 75μm, 78μm, 80μm, 85μm, 90μm, 95μm, 98μm, 100μm, 104μm, 108μm, 110μm, 115μm, 116μm, 118μm and 120μm, etc.

[0147] Optionally, the single-side coating density of the active material layer 131 is in the range of 180 g / m 2 Up to 280g / m 2 Specifically, the single-side coating density of the active material layer 131 may be, but is not limited to, 180 g / m 2 , 185g / m 2 , 190g / m 2 , 200g / m 2 , 205g / m 2 , 210g / m 2 , 220g / m 2 , 225g / m 2 , 230g / m 2 , 235g / m 2 , 240g / m 2 , 245g / m 2 , 250g / m 2 , 260g / m 2 , 270g / m 2 , 275g / m 2 and 280g / m 2 wait.

[0148] Optionally, the resistivity of the positive electrode plate 130 ranges from 0.1 Ω·m to 0.6 Ω·m. When a second polymer is added to the active material layer 131, the positive electrode plate 130 still has a relatively low resistivity, thereby preventing the addition of the second polymer from affecting the ion transport efficiency of the active material layer 131. Specifically, the resistivity of the positive electrode plate 130 may be, but is not limited to, 0.1 Ω·m, 0.15 Ω·m, 0.2 Ω·m, 0.25 Ω·m, 0.28 Ω·m, 0.3 Ω·m, 0.35 Ω·m, 0.4 Ω·m, 0.45 Ω·m, 0.5 Ω·m, 0.55 Ω·m, 0.58 Ω·m, and 0.6 Ω·m.

[0149] Optionally, the peel strength of the positive electrode sheet 130 ranges from 18 N / m to 30 N / m, wherein the peel strength of the positive electrode sheet 130 refers to the peel strength between the active material layer 131 and the positive electrode current collector layer 132. The positive electrode sheet 130 has a large peel strength because the second polymer of the active material layer 131 can effectively bond the active particles in the active material layer 131 and improve the bonding performance between the active material layer 131 and the positive electrode current collector layer 132.

[0150] Optionally, the active material layer 131 also includes a positive electrode conductor and a positive electrode binder. The active particles, the positive electrode conductor, the positive electrode binder and the second polymer are mixed and dispersed in the active material layer 131. The positive electrode conductor is used to improve the conductivity of the active material layer 131, and the positive electrode binder is used to bond the active particles and the second polymer, etc., so as to improve the overall performance of the active material layer 131.

[0151] Optionally, in a specific embodiment, the positive electrode binder is selected from polyvinylidene fluoride.

[0152] Optionally, the positive electrode conductive agent includes at least one of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon nanotubes, graphene and carbon nanofibers.

[0153] Optionally, in the active material layer 131, the mass ratio of the active particles, the positive electrode conductor, the positive electrode binder, and the second polymer is in the range of (94-99):(0.1-2):(0.5-5):(0.1-2). In other words, the active material layer 131 is composed of the active particles, the positive electrode conductor, the positive electrode binder, and the second polymer, with the active particles accounting for 94% to 99% by mass, the positive electrode conductor accounting for 0.1% to 2% by mass, the positive electrode binder accounting for 0.5% to 5% by mass, and the second polymer accounting for 0.1% to 2% by mass.

[0154] Optionally, the preparation process of the positive electrode plate 130 is selected from at least one of slit extrusion, transfer coating, gravure roller coating, spray coating, etc.

[0155] Please also see Figure 9 The present application also provides a battery 200 , which includes: the electrode assembly 100 provided in the present application and an electrolyte 210 , wherein the electrolyte 210 is used to soak at least a portion of the electrode assembly 100 .

[0156] Optionally, in some embodiments, the battery 200 is a lithium-ion battery.

[0157] It can be understood that the electrolyte 210 includes active ions such as lithium ions. During the charge and discharge cycle of the battery 200 , the active ions are transferred between the positive electrode plate 130 and the negative electrode plate 110 .

[0158] Understandably, Figure 9 The embodiment is illustrated by taking a square battery as an example, which should not be understood as limiting the shape of the battery 200 .

[0159] In this embodiment, the battery 200 includes the electrode assembly 100 provided herein. The electrode assembly 100 can produce a good bonding effect under low or moderate pressure. The electrode assembly 100 has good manufacturing performance, which helps reduce the manufacturing cost of the electrode assembly 100, and thus reduces the manufacturing cost of the battery 200. In addition, during the manufacturing process of the electrode assembly 100, it is not necessary to use high pressure for pressing to avoid damaging the structure of the base film 121 of the separator 120, thereby avoiding affecting the ion transmission efficiency. The battery 200 has good cycle performance. Furthermore, in the electrode assembly 100, due to the hydrogen bonds formed between the first polymer and the second polymer, the glue layer 122 and the active material layer 131 have a better fit. Even in the innermost circle of the wound structure formed by the positive electrode plate 130, the separator 120 and the negative electrode plate 110, the positive electrode plate 130 and the separator 120 have good adhesion properties, which can avoid wrinkles or purple spots on the negative electrode plate 110, so that the battery 200 has better cycle performance.

[0160] The following is a further introduction to the technical solution of this application in multiple embodiments:

[0161] Example 1 to Example 4, Comparative Example 1 to Comparative Example 3:

[0162] 1. Preparation of diaphragm 120:

[0163] (1) Preparation of the solution of the adhesive layer 122:

[0164] The mass ratio of PVDF-HFP powder, polyacrylic acid, acrylic resin emulsion, a first polymer (taking polyurethane as an example), and a surfactant is obtained, wherein the first polymer is dispersed in water to form a dispersion, and the surfactant (taking polyvinyl alcohol as an example) is dispersed in water.

[0165] First, deionized water was added as a solvent to the stirrer, and then weighed polyacrylic acid was added. After stirring evenly at a rate of 1000 rpm / 15 min, the dispersion of the first polymer was added and stirred evenly at a rate of 1000 rpm / 15 min. The temperature was controlled at about 40°C and the pH was controlled at about 7. Then, polyvinylidene fluoride-hexafluoropropylene copolymer powder was added and stirred evenly at a rate of 2500 rpm / 90 min. Then, the acrylic resin emulsion was added and stirred evenly at a rate of 1000 rpm / 15 min. Then, the mixture was slowly stirred at a rate of 500 rpm / 15 min to eliminate bubbles. After standing for 3 to 12 hours, the solutions of the adhesive layer 122 of Examples 1 to 4 and Comparative Examples 1 to 3 were obtained.

[0166] (2) Preparation of diaphragm 120:

[0167] The solution of the adhesive layer 122 is applied to one side of the base film 121 using a plate roller coating device. If the diaphragm 120 contains a ceramic coating 123, the adhesive layer 122 is applied to the surface of the ceramic coating 123. If the diaphragm 120 does not contain a ceramic coating 123, the adhesive layer 122 is directly applied to the surface of the base film 121. The thickness of the ceramic coating 123 is 2 μm, and the base film 121 is a polyethylene (PE) porous film with a thickness of 7 μm. After drying at 65°C, the diaphragm 120 with the adhesive layer 122 is obtained and cut into pieces for use. The single-sided surface density of the adhesive layer 122 is 0.5 g / m 2 The diameter (d) of a single glue dot is about 388 μm, the distance between the centers of adjacent glue dots in the MD direction is 688 μm, the distance between the centers of adjacent glue dots in the TD direction is 675 μm, the coverage S of the glue layer 122 on the base film 121 is 25.40%, the tape running speed of the diaphragm 120 is 100 m / min, and the single-side surface density of the glue layer 122 is 0.5 g / m 2 , the radial size of the glue point is 388 μm, thereby obtaining the diaphragms 120 of Examples 1 to 4 and Comparative Examples 1 to 3. Specifically, the scanning electron microscope spectrum of the glue layer 122 of the diaphragm 120 in Example 1 is as follows: Figure 10 and Figure 11 shown. Figure 11 The structure shown is the glue point. Figure 10The adhesive layer 122 is formed by a plurality of adhesive dots, and the adhesive layer 122 is a dot matrix adhesive layer 122 .

[0168] Among them, in the glue layer 122 of the diaphragm 120 of Examples 1 to 4 and Comparative Examples 1 to 3, the mass percentage a1 of the first polymer, the mass percentage a3 of the surfactant, the viscosity of the dispersion of the first polymer, the unit area pressure P of the diaphragm 120, the peel strength Q between the diaphragm 120 and the positive electrode sheet 130 in the innermost circle of the winding structure, the number of glue points within a width of 20 mm, the average peel strength of a single glue point, the value of SP×Q, and the value of the ionic conductivity of the diaphragm 120 are shown in Table 1.

[0169] Specifically, the single-side surface roughness of the adhesive layer 122 is tested by referring to the standard "GB / T 20220-2006 Plastic film and sheet sample average thickness, roll average thickness and unit mass area determination weighing method", using a 100cm 2 Use a gram weight sampler to cut 5 pieces of base film 121 and 5 pieces of diaphragm 120 with adhesive layer 122, weigh them respectively to get the mass, and then divide the mass by the sampling area to get the respective surface density. The difference between the two is the single-sided surface density of the adhesive layer 122. Test 5 times and take the average value.

[0170] Specifically, the coverage S of the adhesive layer 122 on the base film 121 is tested using a 3D microscope (Keyence VHX-7000) with an ultra-depth of field. The area of ​​the adhesive spots on the surface of the diaphragm 120 is identified and calculated at a magnification of 50x. Within a target area (e.g., a 17 mm x 13 mm rectangular area), the total area of ​​the adhesive spots is denoted as S1, and the area of ​​the diaphragm 120 is denoted as S2. The coverage S of the adhesive layer 122 on the base film 121 is calculated as (S1 / S2) x 100%. Three target areas are randomly selected for testing and the average value is calculated.

[0171] Specifically, in the innermost circle of the winding structure, the peel strength Q between the separator 120 and the positive electrode sheet 130 is tested as follows:

[0172] (1) Prepare a bare cell. The pressing method of the bare cell is as follows: normally wind or stack the positive electrode sheet 130, the separator 120 and the negative electrode sheet 110 to form a bare cell, place it in a flat press and press it, and place a layer of Teflon isolation film on the top and bottom. The room temperature pressing temperature is 25°C, the pressure holding time is 40s, and the pressure per unit area is 2.8MPa to 4.8MPa.

[0173] (2) Peel strength test: The bare cell is disassembled layer by layer, and the innermost positive electrode sheet 130 and the diaphragm 120 are bonded together. The test is performed according to the standard "GB / T 2792-2014 Test method for peel strength of adhesive tape". The sample size is cut to 20mm×100mm and fixed in the middle of the clamp of the tensile testing machine. Then, the tensile testing machine is used to peel the diaphragm 120 and the positive electrode sheet 130 along the 180° direction at a speed of 50mm / min. The test distance is up to 80mm. The average value of 5 tests is taken. The bonding strength Q is the average value of the peel strength.

[0174] Specifically, the ionic conductivity of the separator 120 is tested and calculated according to the ionic conductivity test method in 6.6.2 of the standard "GB / T 36363-2018 Polyolefin separator 120 for lithium-ion batteries 200", and the ionic conductivity σ of the separator 120 is tested and calculated.

[0175] 2. Preparation of positive electrode sheet 130:

[0176] Active particles of lithium iron phosphate (LiFePO4), a positive electrode conductive agent, conductive carbon black (Super-P), a positive electrode binder, polyvinylidene fluoride (PVDF), and a second polymer, polydopamine (PDA), were mixed in a mass ratio of 97:1:1.6:0.4. N-methylpyrrolidone (NMP) was then added as a solvent and stirred evenly to form a positive electrode slurry with a solid content of 60 wt%. The positive electrode slurry was then evenly coated on one surface of an 11 μm thick positive electrode current collector layer 132 (aluminum foil) and dried at 85°C. The above steps were then repeated on the other surface of the positive electrode sheet 130. After roll pressing, a positive electrode sheet 130 coated on both sides with an active material layer 131 was obtained, i.e., the positive electrode sheets 130 of Examples 1 to 4 and Comparative Examples 1 to 3 were obtained. The thickness of the active material layer 131 on a single side was 85 μm.

[0177] Among them, in the active material layer 131 of Examples 1 to 4 and Comparative Examples 1 to 3, the values ​​of the mass percentage a2 of the second polymer, the viscosity of the positive electrode slurry, the peel strength of the positive electrode sheet 130, and the resistivity of the positive electrode sheet 130 are shown in Table 2.

[0178] The peel strength of the positive electrode sheet 130 refers to the peel strength between the active material layer 131 and the positive electrode current collector layer 132 .

[0179] 3. Preparation of negative electrode sheet 110:

[0180] The negative electrode active materials, artificial graphite, conductive carbon black (Super-P), sodium carboxymethyl cellulose (CMC-Na), and styrene-butadiene rubber (SBR), were mixed in a mass ratio of 97:1:1.5:0.5. Deionized water was added and stirred thoroughly to form a negative electrode slurry with a solid content of 55 wt%. The negative electrode slurry was then evenly coated on one surface of a 6 μm thick negative electrode current collector layer (copper foil) and dried at 105°C. The above steps were then repeated on the other surface of the negative electrode sheet 110. After roller pressing, the negative electrode sheet 110 was coated on both sides with a negative electrode material layer. The thickness of the negative electrode material layer on each side was 65 μm.

[0181] 4. Preparation of electrolyte 210:

[0182] Ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) are mixed in a volume ratio of 1:1:1, dissolved, and thoroughly stirred, and then placed at a temperature of 5°C or less for 12 hours. Lithium hexafluorophosphate (LiPF6) is then added and mixed uniformly to obtain an electrolyte solution 210. The molar concentration of LiPF6 in the electrolyte solution 210 is 1.0 mol / L.

[0183] 5. Preparation of Battery 200:

[0184] The positive electrode sheet 130, separator 120, and negative electrode sheet 110 prepared above were arranged in order, with the separator 120 placed between the positive and negative electrodes to act as a separator, and then wound to obtain a wound structure. The wound structure was pressed at room temperature for 40 seconds, and the pressure per unit area of ​​the separator 120 was 2.8 MPa to 4.8 MPa. Finally, the wound structure was placed in an aluminum alloy square shell, vacuum dried, and then injected with electrolyte 210. After vacuum packaging, standing, and formation, the implementation cells 1 to 4 and the comparison cells 1 to 3 were obtained.

[0185] Among them, the diaphragm 120 and the positive electrode plate 130 of Example 1 are used to implement battery 1, the diaphragm 120 and the positive electrode plate 130 of Example 2 are used to implement battery 2, the diaphragm 120 and the positive electrode plate 130 of Comparative Example 1 are used to compare battery 1, and so on.

[0186] Table 1: Structural parameters and performance parameters of the diaphragm 120 of Examples 1 to 4 and Comparative Examples 1 to 3.

[0187]

[0188] The average peel strength of a single glue point is calculated by the ratio of Q to the number of glue points within a width of 20 mm.

[0189] Table 2: Structural parameters and performance parameters of the positive electrode sheets 130 of Examples 1 to 4 and Comparative Examples 1 to 3.

[0190]

[0191] Performance test of battery 200:

[0192] 1. Energy efficiency of battery 200:

[0193] At 25°C, batteries 1 through 4 and comparative batteries 1 through 3 were cycled at 0.5P charge and 0.5P discharge, with a charge cutoff voltage of 3.7V and a discharge cutoff voltage of 2.45V, until the capacity of battery 200 reached 60% of its initial capacity. The energy efficiency of lithium-ion battery 200 after two cycles was measured using a constant current method: energy efficiency = discharge energy in the second cycle / charge energy in the second cycle × 100%.

[0194] The energy efficiency values ​​of the implementation batteries 1 to 4 and the comparison batteries 1 to 3 after 2 cycles are shown in Table 3.

[0195] 2. After the battery 200 undergoes charge and discharge cycles, the wrinkles on the interface of the negative electrode sheet 110 are:

[0196] According to the operating specifications, the fully charged implementation batteries 1 to implementation batteries 4 and comparison batteries 1 to comparison batteries 3 were disassembled. The humidity in the disassembly room was ≤5% RH and the temperature was 25±3°C. Photos were taken to record the interface wrinkles of the negative electrode plate 110. Starting from the inner circle of the bare cell, if the number of wrinkles on the negative electrode plate 110 is 0, it is determined to be wrinkle-free; if the number of wrinkles on the negative electrode plate 110 is 1 to 3, it is determined to be extremely slightly wrinkled; if the number of wrinkles on the negative electrode plate 110 is 4 to 6, it is determined to be slightly wrinkled; if the number of wrinkles on the negative electrode plate 110 is 7 or more, it is determined to be obviously wrinkled. Specifically, in the electrode assembly 100 of Example 1, the interface wrinkles of the negative electrode plate 110 of the inner circle after full charge are as follows. Figure 12 As shown, in the electrode assembly 100 of comparative example 1, the interface wrinkles of the negative electrode sheet 110 of the inner ring after full charge are as follows: Figure 13 shown.

[0197] Among them, after the charge and discharge cycles of the implementation batteries 1 to 4 and the comparison batteries 1 to 3, the wrinkles of the negative electrode sheets 110 are shown in Table 3.

[0198] Table 3: Performance parameters of Example Batteries 1 to 4 and Comparative Batteries 1 to 3.

[0199]

[0200] Please see Tables 1 to 3. Figure 12 and Figure 13It can be seen from the data of Examples 1 to 4 and Comparative Examples 1 to 3 that the glue layer 122 of the diaphragm 120 of Examples 1 to 4 all include the first polymer and the surfactant, and the positive electrode plates 130 of Examples 1 to 4 all include the second polymer, while the glue layer 122 of the diaphragm 120 of Comparative Example 1 does not include the first polymer and the surfactant, and the positive electrode plate 130 of Comparative Example 1 does not include the second polymer. The glue layer 122 of the diaphragm 120 of Comparative Example 2 includes the first polymer but does not include the surfactant, and the positive electrode plate 130 of Comparative Example 2 includes the second polymer. The glue layer 122 of the diaphragm 120 of Comparative Example 3 does not include the first polymer but includes the surfactant, and the positive electrode plate 130 of Comparative Example 3 includes the second polymer. This means that the energy efficiency of implementation batteries 1 to implementation batteries 4 after two cycles at 25°C is higher than the energy efficiency of comparison batteries 1 to comparison batteries 3 after two cycles at 25°C, and no wrinkles appear on the interface of the negative electrode plate 110 of the inner circle of implementation batteries 1 to implementation batteries 4 after full charge, while comparison batteries 1 to comparison batteries 3 show obvious wrinkles, slight wrinkles and slight wrinkles, respectively. This shows that: in Examples 1 to 4, the surfactant promotes the formation of hydrogen bonds between the first polymer and the second polymer to enhance the interfacial adsorption force between the glue layer 122 and the active material layer 131, thereby enhancing the bonding performance between the separator 120 and the positive electrode sheet 130. When the electrode assembly 100 is applied to the battery 200 and the battery 200 undergoes charge and discharge cycles, the negative electrode sheet 110 of the inner circle of the winding structure formed by the positive electrode sheet 130, the separator 120 and the negative electrode sheet 110 still does not have wrinkles, which is beneficial to improving the energy efficiency and cycle performance of the battery 200 when the electrode assembly 100 is applied to the battery 200. The electrode assembly 100 of Comparative Example 1 includes neither the first nor the second polymer, resulting in the poorest adhesion between the separator 120 and the positive electrode sheet 130 in Comparative Battery 1. Consequently, the interface of the inner-wound negative electrode sheet 110 exhibits more wrinkles, making lithium deposition and purple spots more likely to occur, deteriorating the cycling performance and energy efficiency of Comparative Battery 1. The electrode assembly 100 of Comparative Example 2 incorporates both the first and second polymers but lacks a surfactant, resulting in lower energy efficiency for Comparative Battery 2 than for Example Batteries 1 through 4. This suggests that the surfactant plays a role in promoting hydrogen bonding between the first and second polymers. The electrode assembly 100 of Comparative Example 3 includes only the second polymer, making it difficult to form hydrogen bonds between the separator 120 and the active material layer 131, and thus difficult to improve adhesion between the separator 120 and the positive electrode sheet 130. Consequently, wrinkles appear on the inner-wound negative electrode sheet 110 after full charge.

[0201] Furthermore, it can be seen from the data of Examples 1 to 3 that when the mass percentage of the second polymer of the positive electrode plate 130 remains unchanged and the unit area pressure of the diaphragm 120 remains unchanged, if the mass percentage of the first polymer and the mass percentage of the surfactant meet the reasonable range, as the mass percentage of the first polymer and the mass percentage of the surfactant increase, the peel strength between the diaphragm 120 and the positive electrode plate 130 in the innermost circle of the winding structure gradually increases, and SP×Q meets the reasonable range. This shows that: as the mass percentage of the first polymer increases, the first polymer can form more hydrogen bonds with the second polymer, and under the same pressing pressure, the interfacial adsorption force between the glue layer 122 and the positive electrode plate 130 can be improved, so that the diaphragm 120 has better adhesion performance to the positive electrode plate 130.

[0202] Furthermore, the data from Examples 2 and 4 show that, while the mass percentage of the first polymer and the mass percentage of the surfactant in the separator 120 remain unchanged, increasing the pressure per unit area of ​​the separator 120 can increase the peel strength between the separator 120 and the positive electrode sheet 130. Furthermore, increasing the mass percentage of the second polymer can increase the viscosity of the positive electrode slurry and the peel strength of the positive electrode sheet 130. This indicates that the second polymer can exert a bonding effect on the active particles in the active material layer 131, thereby improving the performance of the electrode assembly 100.

[0203] See Figure 14 and Figure 15 The present application also provides an electrical device 300 , which includes: a device body 310 and a battery 200 provided in the present application, wherein the battery 200 supplies power to the device body 310 .

[0204] It can be understood that the battery 200 is electrically connected to the electrical device 300 .

[0205] In this embodiment, the battery 200 includes the electrode assembly 100 and the electrolyte 210 provided in this application. The electrode assembly 100 has good preparation performance and usage performance, so that the battery 200 has good cycle stability and usage performance. The battery 200 has a long service life. When the battery 200 is applied to the electrical device 300, the battery 200 can provide stable power to the device body 310, which is beneficial to improving user experience.

[0206] Optionally, the power-consuming device 300 of the embodiment of the present application may be, but is not limited to, a mobile phone, tablet computer, laptop computer, desktop computer, smart bracelet, smart watch, e-reader, game console and other portable electronic devices. It may also be a vehicle such as a car, truck, car, van, truck, motor vehicle, high-speed rail, electric automatic vehicle and other vehicles. In addition, it may also be various household appliances, etc. Figure 14 The electrical equipment 300 in the embodiment is an energy storage battery cabinet.

[0207] It can be understood that the electrical device 300 described in this embodiment is merely a form of the electrical device 300 used by the battery 200, and should not be understood as a limitation on the electrical device 300 provided in this application, nor should it be understood as a limitation on the electrical device 300 provided in each embodiment of this application.

[0208] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, unless there is a contradiction between them.

[0209] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrode assembly, characterized in that: The electrode assembly comprises: negative electrode; a diaphragm, the diaphragm being disposed on one side of the negative electrode plate, the diaphragm comprising a base film and a glue layer, the glue layer being disposed on at least one side of the base film, the glue layer comprising a first polymer, the first polymer being a polymer having one of a urethane bond and an epoxy bond; and A positive electrode plate is provided on the side of the base film where the glue layer is provided; the positive electrode plate includes an active material layer, the active material layer includes a second polymer, and the second polymer is a polymer having amino groups and hydroxyl groups.

2. The electrode assembly according to claim 1, wherein The first polymer includes one of polyurethane, amino acrylic resin, epoxy resin, and epoxy acrylate; the second polymer includes one of polydopamine, polydopamine derivatives, copolymers containing dopamine, and chitosan.

3. The electrode assembly according to claim 1, wherein The electrode assembly includes at least one of the following features: The mass ratio q1 of the first polymer to the second polymer satisfies the range: 10 / 3≤q1≤100; The weight average molecular weight M1 of the first polymer satisfies the range: 800≤M1≤30000; The weight average molecular weight M2 of the second polymer satisfies the range of 2000≤M2≤200000.

4. The electrode assembly according to any one of claims 1 to 3, characterized in that: The electrode assembly includes at least one of the following features: In the adhesive layer, the mass percentage a1 of the first polymer is in the range of: 0.5%≤a1≤5%; In the active material layer, the mass percentage content a2 of the second polymer is in the range of 0.1%≤a2≤2%.

5. The electrode assembly according to any one of claims 1 to 3, characterized in that: The adhesive layer further comprises a surfactant, and the surfactant is selected from at least one of polyvinyl alcohol, epoxysilane hydroxyl, ethyl cellulose, fatty acid ester, carboxylic acid ester, lactic acid ester and cellulose ester.

6. The electrode assembly according to claim 5, characterized in that The mass ratio q2 of the first polymer to the surfactant satisfies the range of 5≤q2≤50.

7. The electrode assembly according to claim 5, characterized in that In the adhesive layer, the mass percentage content a3 of the surfactant is in the range of 0.1%≤a3≤2%.

8. The electrode assembly according to any one of claims 1 to 3, characterized in that: The negative electrode sheet, the separator and the positive electrode sheet are stacked and then wound to form a wound structure. The electrode assembly is pressed for 40 seconds at room temperature. The unit area pressure of the separator is P. In the innermost circle of the wound structure, the peel strength between the separator and the positive electrode sheet is Q. The coverage of the adhesive layer on the base film is S. Then, the electrode assembly satisfies the relationship: 0≤(SP×Q)≤20.

9. The electrode assembly according to claim 8, characterized in that The electrode assembly includes at least one of the following features: The coverage S of the adhesive layer on the base film is in the range of: 5%≤S≤30%; The electrode assembly is pressed for 40 seconds at room temperature, and the range of the unit area pressure P of the separator is: 2.8 MPa≤P≤4.8 MPa; In the innermost circle of the winding structure, the peel strength Q between the separator and the positive electrode sheet is in the range of 1.5 N / m≤Q≤5 N / m.

10. A battery, characterized in that: The battery comprises: The electrode assembly according to any one of claims 1 to 9; and An electrolyte is used to soak at least a portion of the electrode assembly.

11. An electrical device, characterized in that: The electrical equipment includes: the device itself; and The battery according to claim 10, wherein the battery is used to power the device body.

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