Diaphragm, dispensing roller, single battery and energy storage device

Abstract

The invention provides a diaphragm, a dispensing roller, a single battery and an energy storage device. The diaphragm comprises: a base film having a first surface and a second surface opposite to each other; the first adhesive layer comprises a plurality of first adhesive point parts which are arranged on the first surface in an array; the first adhesive layer comprises a first surface and a second surface, the second adhesive layer comprises a plurality of adhesive point units, the plurality of adhesive point units are arranged on the second surface at intervals, each adhesive point unit comprises a plurality of second adhesive point parts which are arranged at intervals, and the distance between every two adjacent second adhesive point parts in each adhesive point unit in the first direction is arranged in a cosine sequence.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a separator, a coating roller, a single cell, and an energy storage device. Background Technology

[0002] Due to the characteristics of the positive electrode polyanionic material and the negative electrode hard carbon material, sodium batteries exhibit significant looseness in the bare cell openings after winding, severely impacting the wrapping of the bare cell with Mylar membrane and the casing process. Therefore, the separator needs to adopt a double-sided adhesive structure, meaning that after hot pressing, the bare cell forms a shape similar to a "hard brick".

[0003] In related technologies, the separator is coated with adhesive layers on both sides of the base film. However, the thickness uniformity of the adhesive layers produced by spraying is poor, which can easily cause misalignment of the tabs of the bare cells. Separators using double-sided dispensing have significantly better thickness uniformity between bare cells than those using double-sided spraying. However, for sodium batteries using a winding process, the thickness uniformity within the separator roll is crucial. Although the adhesive dots on both sides of the double-sided dispensing separator are arranged in a regular matrix, the overlapping of the adhesive dots after double-sided dispensing can cause thickness fluctuations. When both sides of the separator use the same regular dot matrix, the dots tend to overlap at specific locations, resulting in localized doubling of thickness. At the beginning of the coating process, adhesive dots are first applied to one surface of the separator. Then, by adjusting the initial position of the adhesive dots on the other surface, the adhesive dots on both sides can be completely overlapped. At this point, the thickness of the separator is the base film plus two layers of adhesive dots. This process can continue for tens of meters. However, during the coating process, equipment fluctuations or elastic deformation during diaphragm coating can cause the adhesive dots on the second surface to shift, resulting in misalignment of the originally overlapping dots. At this point, the diaphragm thickness is the base film plus one layer of adhesive dots. This misalignment can continue for tens of meters before another fluctuation occurs, causing the dots to shift again, resulting in partial misalignment or re-overlapping. This manifests as irregular thickness fluctuations across the entire roll of diaphragm, leading to uncontrolled tab gaps, tab misalignment, thinning of the cell, or cell deformation. Because these are uncontrollable factors, the irregular diaphragm thickness fluctuations cannot be easily offset by adjusting equipment process parameters. This problem occurs intermittently during the manufacturing process, severely impacting process yield. Summary of the Invention

[0004] This application provides a separator with good thickness uniformity, which can reduce the defect rate of misaligned tabs in single cells when applied to them.

[0005] In a first aspect, embodiments of this application provide a diaphragm, the diaphragm comprising: The base film has a first surface and a second surface disposed opposite to each other; A first adhesive layer, the first adhesive layer comprising a plurality of first adhesive dots arranged in an array on the first surface; and The second adhesive layer includes a plurality of adhesive dot units, which are spaced apart on the second surface. Each adhesive dot unit includes a plurality of second adhesive dot portions spaced apart. The distance between two adjacent second adhesive dot portions in each adhesive dot unit along a first direction is arranged in a cosine sequence.

[0006] Furthermore, the spacing between two adjacent second adhesive dots is arranged in a sinusoidal sequence, wherein the first direction intersects the second direction.

[0007] Furthermore, along the first direction, the distance between the center point of the nth second adhesive dot and the center point of the (n+1)th second adhesive dot. x = γb × [1 + cos(2πn / N)], where γ is a constant, 0 < γ < 1, N is the number of second glue dots in each row along the first direction in each glue dot unit, and b is the distance between the center points of two adjacent first glue dots, 1 ≤ n ≤ N-1.

[0008] Furthermore, along the second direction, the distance between the center point of the m-th second adhesive dot and the center point of the (m+1)-th second adhesive dot is... y = γb × [1 + sin(2πm / M)], where γ is a constant, 0 < γ < 1, M is the number of second glue dots in each column along the second direction in each glue dot unit, and b is the distance between the center points of two adjacent first glue dots, 1 ≤ m ≤ M-1.

[0009] Furthermore, the plurality of second adhesive dots in the adhesive dot unit are arranged in M ​​rows and N columns; each row extends along a first direction and has N second adhesive dots; each column extends along a second direction and has M second adhesive dots; wherein, 6≤M≤100, 6≤N≤200.

[0010] Furthermore, the diaphragm satisfies at least one of the following conditions: The equivalent circle diameter a1 of the first adhesive dot portion is in the range of: 0.01mm≤a1≤5mm; The distance b between the center points of two adjacent first adhesive dots is in the range of: 0.01mm ≤ b ≤ 10mm; and The equivalent circle diameter a2 of the second adhesive dot is in the range of 0.01mm≤a2≤5mm.

[0011] Furthermore, the plurality of second adhesive dots in the adhesive dot unit are arranged in M ​​rows and N columns; each row extends along a first direction and has N second adhesive dots; each column extends along a second direction and has M second adhesive dots. The x-coordinate of the center point of the nth second glue dot in the mth row along the first direction. for: ; The x-coordinate of the center point of the m-th second adhesive dot in the n-th column along the second direction. for: .

[0012] Secondly, embodiments of this application also provide a dotting roller, the dotting roller comprising: A roller shaft having an axial direction and a circumferential direction; and At least one dotting unit, each dotting unit including multiple dotting sections, the multiple dotting sections being spaced apart in the axial and circumferential directions around the roller shaft; along the axial direction of the roller shaft, the spacing between two adjacent dotting sections is arranged in a cosine sequence.

[0013] Furthermore, along the circumferential direction of the roller shaft, the spacing between two adjacent dots is arranged in a sinusoidal sequence.

[0014] Furthermore, the dotting roller is used to prepare the second adhesive layer of the diaphragm described in the embodiments of this application; Along the axial direction, the distance between the center point of the k1'th dot and the (k1'+1)th dot is... x'=γ'b×[1+cos(2πk1' / N')], where γ' is a constant, 0<γ'<1, N' is the number of dots in each row along the axial direction, b is the distance between the center points of two adjacent first adhesive dots of the diaphragm, 0.01mm≤b≤100mm, 1≤k1'≤N'-1.

[0015] Furthermore, along the circumferential direction, the distance between the center point of the k2'th dot and the center point of the (k2'+1)th dot is... y'=γ'b×[1+sin(2πk2' / M')], where M' is the number of dots in each circle along the circumferential direction, 1≤k2'≤M'-1.

[0016] Thirdly, embodiments of this application also provide a single-cell battery, the single-cell battery including a positive electrode, a separator as described in embodiments of this application, a negative electrode and an electrolyte, wherein the separator is located between the positive electrode and the negative electrode.

[0017] Fourthly, embodiments of this application also provide an energy storage device, the energy storage device comprising: one or more single-cell batteries as described in embodiments of this application.

[0018] The diaphragm in this embodiment includes a base film, a first adhesive layer, and a second adhesive layer. The base film has a first surface and a second surface disposed opposite to each other. The first adhesive layer includes a plurality of first adhesive dots arranged in an array on the first surface. The second adhesive layer includes a plurality of adhesive dot units, which are spaced apart on the second surface. Each adhesive dot unit includes a plurality of second adhesive dots arranged at intervals. Along a first direction, the spacing between two adjacent second adhesive dots is arranged in a cosine sequence. This application achieves this by making the spacing between two adjacent second adhesive dots in each adhesive dot unit along the first direction cosine sequence. By actively controlling the overlap pattern of the first and second adhesive dots, the thickness variation of the diaphragm is offset at the microscale, avoiding macroscopic fluctuations in the thickness of the diaphragm. Furthermore, due to the regular overlap mechanism, it can be controllably adjusted by adjusting the parameters of the coating equipment. Even if fluctuations occur, macroscopic stability will be maintained due to the microscopic regularity (i.e., periodic change) of the overlap region. This reduces the thickness fluctuation of each roll of separator. When the separator is applied to a single cell, the thickness fluctuation of the core is greatly reduced, and the misalignment defect rate of the tabs (positive tab and / or negative tab) of the single cell is greatly reduced. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application.

[0022] Figure 3 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application.

[0023] Figure 4 This is a schematic diagram of the structure of an electrical system according to an embodiment of this application.

[0024] Figure 5 This is a schematic diagram of the structure of an energy storage device according to an embodiment of this application.

[0025] Figure 6 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application.

[0026] Figure 7 For the application of an embodiment of the single cell battery Figure 6 A schematic diagram of the cross-sectional structure along the AA direction.

[0027] Figure 8 This is a cross-sectional view of the positive electrode sheet according to an embodiment of this application.

[0028] Figure 9 This is a cross-sectional view of the negative electrode sheet according to an embodiment of this application.

[0029] Figure 10 This is a cross-sectional view of a diaphragm according to an embodiment of this application.

[0030] Figure 11 This is a plan view of the first adhesive layer side of the diaphragm according to an embodiment of this application.

[0031] Figure 12 This is a plan view of the second adhesive layer side of the diaphragm according to an embodiment of this application.

[0032] Figure 13 This is a plan view of the second adhesive layer according to an embodiment of this application.

[0033] Figure 14 This is a schematic diagram of the planar structure after the first adhesive layer and the second adhesive layer are stacked.

[0034] Figure 15 This is a schematic diagram of the structure of a dotting roller according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures: 100 - Energy storage system; 110 - First power conversion device; 120 - First user load; 130 - Second user load; 140 - High-voltage cable; 150 - Second power conversion device; 160 - Photovoltaic-energy storage-charging station; 170 - Automobile; 200 - Energy storage device; 100' - Power consumption system; 110' - Electrical equipment; 300 - Single cell; 310 - Positive electrode sheet; 311 - Positive current collector; 312 - Positive active layer; 313 - Positive tab; 330 - Negative electrode sheet. , 331-Negative electrode current collector, 332-Negative electrode active layer, 333-Negative electrode tab, 340-Housing shell, 341-Receiving cavity, 350-End cap assembly, 400-Separator, 410-Base film, 411-First surface, 412-Second surface, 420-First adhesive layer, 4211-First adhesive dot portion, 430-Second adhesive layer, 431-Adhesive dot unit, 4311-Second adhesive dot portion, 500-Dip coating roller, 510-Roller shaft, 520a-Dip coating unit, 520-Dip coating portion. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0037] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0038] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0039] It should be noted that, for ease of explanation, the same reference numerals denote the same components in the embodiments of this application, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0040] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve energy efficiency, it is necessary to store one form of energy in the same way or by converting it into another, and then release it in a specific energy form based on future application needs. Currently, the main way to generate green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels.

[0041] Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are generally characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak demand periods, and excessive power during off-peak periods. Unstable voltage can also damage the power grid. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar curtailment." Solving these problems requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing it. When needed, this energy can be converted back into electrical energy and released. Simply put, energy storage is like a large "power bank," storing electrical energy when solar and wind power are abundant and releasing the stored electricity when needed.

[0042] Taking electrochemical energy storage as an example, this solution provides an energy storage device for use in energy storage systems. The energy storage device is equipped with a set of chemical batteries, which mainly use the chemical elements in the batteries as energy storage media. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage media. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical batteries. When the use of external electrical energy reaches its peak, the stored electricity is released for use, or transferred to places with a shortage of electricity for use.

[0043] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, and consumption-side energy storage. The corresponding types of energy storage devices include: (1) Large-scale energy storage power stations (composed of multiple prefabricated energy storage modules) applied to wind power and photovoltaic power stations can help renewable energy power generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power regulation power source on the power supply side, the energy storage power station realizes the load matching of power in time and space, enhances the renewable energy absorption capacity, reduces instantaneous power changes, reduces the impact on the power grid, improves the problem of new energy power generation absorption, and is of great significance in power grid system backup, alleviating peak load power supply pressure and peak regulation and frequency regulation. (2) The energy storage prefabricated cabin applied on the grid side mainly functions as peak regulation, frequency regulation and grid congestion relief. In terms of peak regulation, 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 electricity load period, thereby achieving a balance between power production and consumption. (3) Small energy storage cabinets applied to the electricity consumption side mainly function as self-consumption of electricity, peak-valley price arbitrage, capacity cost management, and improvement of power supply reliability. Depending on the application scenario, electricity consumption side energy storage can be divided into industrial and commercial energy storage cabinets, household energy storage devices, 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 electricity market implementing peak-valley pricing, by charging the energy storage system when the electricity price is low and discharging the energy storage system when the electricity price is high, peak-valley price arbitrage can be achieved, reducing electricity costs. In addition, industrial enterprises subject to two-part tariffs can use energy storage systems to store energy during off-peak hours and discharge during peak loads, thereby reducing peak power and the maximum demand declared, achieving the goal of reducing capacity costs. Household photovoltaics with energy storage can improve the level of self-consumption of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installations is driven. Given that photovoltaic power generation occurs during the day, while user load is generally higher at night, configuring energy storage can better utilize photovoltaic power, improve self-consumption levels, and reduce electricity costs. Furthermore, energy storage is needed in areas such as communication base stations and data centers for backup power.

[0044] In some embodiments, see Figure 1 , Figure 1 This is a schematic diagram of the structure of an energy storage system 100 according to an embodiment of this application. Figure 1 The embodiments are illustrated using a home energy storage scenario in user-side energy storage as an example. The energy storage device 200 of this application is not limited to the home energy storage scenario.

[0045] Please see Figure 1 This application provides an energy storage system 100, which includes a first power conversion device 110 (photovoltaic panel), a first user load 120 (household lighting fixture), a second user load 130 (e.g., household appliances such as air conditioners), and an energy storage device 200. The energy storage device 200 is a small energy storage box that can be wall-mounted on an outdoor wall. However, the energy storage device 200 is not limited to wall mounting and can also be placed in a user's residence in other ways. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices, and the energy storage device 200 stores this electrical energy and supplies it to lighting fixtures and household appliances during peak electricity prices, or provides power during power outages / power interruptions.

[0046] In some embodiments, see Figure 2 , Figure 2 This is a schematic diagram of the structure of an energy storage system 100 according to another embodiment of this application, and this application Figure 2 The embodiments are illustrated using a shared energy storage scenario on the generation / distribution side as an example. The energy storage device 200 of this application is not limited to its generation / distribution side energy storage scenario.

[0047] This application provides an energy storage system 100, which includes: a high-voltage cable 140, a first power conversion device 110, a second power conversion device 150, and an energy storage device 200 provided in this application. In some embodiments of the power generation scenario, the second power conversion device 150 can be a wind power conversion device. Since the electricity generated by wind power conversion is volatile, random, and intermittent, the unstable electricity output by the wind power conversion device can be stored in the energy storage device 200 through grid connection. The energy storage device 200 is connected to the high-voltage cable 140 and outputs smooth electricity to the power consumption side of the distribution network, realizing peak shaving and frequency regulation, and stable grid operation; or, wind power conversion... The power conversion device is always connected to the high-voltage cable 140. Under normal power generation conditions, the power output of the wind power conversion device is supplied to the power consumption side of the distribution network through the high-voltage cable 140. 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 200 to reduce wind and solar curtailment rates and improve the problem of new energy power generation consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 200 together with the high-voltage cable 140 in grid-connected mode to supply power to the power consumption side. This provides the power grid with various services such as peak shaving, frequency regulation, and backup, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling, and alleviating the power supply pressure of the power grid.

[0048] In some embodiments on the distribution network side, the first power conversion device 110 can be a photovoltaic panel, and the energy storage device 200 is connected to the high-voltage cable 140 and installed downstream of the high-voltage cable 140 between the user load and the photovoltaic power conversion device. The electrical energy output by the photovoltaic power conversion device is stored in the energy storage device 200, which can respond in a timely manner to act as a backup power source when the power grid / distribution network fails; or, it can provide power supply support to alleviate line congestion when the high-voltage cable 140 transmission line is blocked, and to delay the economic pressure caused by the expansion of the power grid / distribution capacity when the power grid is planned to be expanded.

[0049] In some embodiments, see Figure 3 , Figure 3 This is a schematic diagram of the structure of an energy storage system 100 according to another embodiment of this application, and this application Figure 3 The embodiments are illustrated using an industrial and commercial energy storage scenario as an example. The energy storage device 200 of this application is not limited to industrial and commercial energy storage scenarios.

[0050] This application provides an energy storage system 100, which includes: an energy storage device 200, a high-voltage cable 140, a factory equipped with a first power conversion device 110, a photovoltaic-energy storage-charging station 160, and a vehicle 170. In some embodiments of industrial and commercial scenarios, the first power conversion device 110 can be a photovoltaic panel, which converts solar energy into electrical energy and stores it in the energy storage device 200 in the factory. In the event of a power grid failure, the energy storage device 200 provides power to ensure the safe and stable operation of the factory without interruption. Alternatively, when the factory's power load is high, the power grid issues an instruction to transmit the electricity stored in the energy storage device 200 in conjunction with the high-voltage cable 140 in a grid-connected mode to supply the factory with electricity, providing various services such as peak shaving / frequency regulation and backup for the power grid operation. In addition, the first power conversion device 110 can also convert solar energy into electrical energy and store it in the energy storage device 200 of the photovoltaic-energy storage-charging station 160, which can directly charge the vehicle 170, making it fast and convenient.

[0051] Optionally, the first power conversion device 110 may include, but is not limited to, a photovoltaic panel, and the second power conversion device 150 may include, but is not limited to, a wind power conversion device. The first power conversion device 110 and the second power conversion device 150 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0052] Figure 4 This is a schematic diagram of the structure of an electrical system 100' according to an embodiment of this application.

[0053] Please see Figure 4 This application embodiment also provides an electrical system 100', which includes an electrical device 110' and an energy storage device 200. The energy storage device 200 is electrically connected to the electrical device 110' and is used to supply power to the energy storage device 200.

[0054] Optionally, the electrical equipment 110' can be, but is not limited to, at least one of the following: power grid, base station, household appliances (such as air conditioner, refrigerator, washing machine, etc.).

[0055] Optionally, the electrical equipment 110' and the energy storage device 200 can be electrically connected via a high-voltage cable 140.

[0056] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of an energy storage device 200 according to an embodiment of this application.

[0057] Optionally, the energy storage device 200 includes one or more individual battery cells 300.

[0058] The term "multiple" refers to two or more, such as, but not limited to, 2, 5, 10, 30, 50, 100, 200, 300, 400, 800, 1000, etc.

[0059] It should be noted that the number of individual battery cells 300 included in the energy storage device 200 can be determined based on the rated capacity of the individual battery cells 300 and the rated capacity that the energy storage device 200 is to achieve.

[0060] Optionally, the energy storage device 200 can be used, but is not limited to, 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 applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0061] Optionally, the energy storage device 200 may include, but is not limited to, battery integrated systems comprising a single battery cell 300, or battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage containers, etc., composed of single battery cells 300. In other words, when the energy storage device 200 includes a single battery cell 300, the energy storage device 200 may exist in the form of a single battery cell 300. When the energy storage device 200 includes multiple single battery cells 300, the multiple single battery cells 300 may be stacked, arranged, assembled, etc., to form battery integrated systems such as battery modules, battery packs, battery clusters, power banks, energy storage cabinets / energy storage containers, etc.; that is, the energy storage device 200 exists in the form of battery integrated systems such as battery modules, battery packs, battery clusters, power banks, energy storage cabinets / energy storage containers, etc. The actual application form of the energy storage device 200 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 200. In the embodiments of this application, the energy storage device 200 is illustrated by taking a multi-cell battery (i.e., multiple single cells 300) as an example.

[0062] Optionally, the single cell 300 can be, but is not limited to, at least one of cylindrical, square, prismatic, or other shaped cells.

[0063] Optionally, the single cell 300 can be a rechargeable battery, which refers to a single cell 300 that can be recharged after discharge to activate the active materials and continue to be used. The single cell 300 can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not specifically limit it.

[0064] Understandably, the 300 single cell can be, but is not limited to, sodium batteries, lithium batteries, magnesium batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0065] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of a single cell battery 300 according to an embodiment of this application. Figure 7 For an embodiment of the application, a single cell 300 is applied for. Figure 6 A schematic diagram of the cross-sectional structure along the AA direction.

[0066] Please see Figure 6 and Figure 7 This application provides a single-cell battery 300, which includes a positive electrode 310, a separator 400, a negative electrode 330, and an electrolyte. The separator 400 is located between the positive electrode 310 and the negative electrode 330.

[0067] Understandably, the positive electrode 310 and the negative electrode 330 are located on opposite sides of the separator 400, that is, the separator 400 is located between the positive electrode 310 and the negative electrode 330, separating them. The positive electrode 310, the separator 400, and the negative electrode 330 are sequentially stacked to obtain an electrode assembly, which is then wound to obtain a core (not shown). That is, the core includes the positive electrode 310, the separator 400, and the negative electrode 330.

[0068] Optionally, the positive electrode 310, the separator 400, and the negative electrode 330 are all at least partially immersed in the electrolyte.

[0069] Figure 8 This is a cross-sectional view of the positive electrode 310 according to an embodiment of this application.

[0070] Please see Figure 8 Optionally, the positive electrode 310 includes a positive current collector 311, a positive active layer 312, and a plurality of positive tabs 313. The positive active layer 312 is disposed on at least one of two opposite surfaces of the positive current collector 311, and the plurality of positive tabs 313 are disposed on the same side of the positive current collector 311 and are electrically connected to the positive current collector 311 respectively.

[0071] Figure 9 This is a cross-sectional view of the negative electrode 330 according to an embodiment of this application.

[0072] Please see Figure 9Optionally, the negative electrode 330 includes a negative electrode current collector 331, a negative electrode active layer 332, and a plurality of negative electrode tabs 333. The negative electrode active layer 332 is disposed on at least one of two opposing surfaces of the negative electrode current collector 331, and the plurality of negative electrode tabs 333 are disposed on the same side of the negative electrode current collector 331 and are electrically connected to the negative electrode current collector 331 respectively. The positive electrode tab 313 and the negative electrode tab 333 can be collectively referred to as electrode tabs.

[0073] Please see again Figure 6 and Figure 7 Optionally, the single-cell battery 300 further includes a housing 340 and an end cap assembly 350, the housing 340 and the end cap assembly 350 forming a closed receiving cavity 341 for housing the electrolyte, the positive electrode 310, the separator 400, and the negative electrode 330. Understandably, the end cap assembly 350 electrically connects the positive electrode 310 and the negative electrode 330, leading them out for electrical connection to external devices or other single-cell batteries 300.

[0074] Due to the characteristics of the positive electrode (polyanionic) and negative electrode (hard carbon), sodium-ion batteries exhibit significant looseness in the exposed cell openings after winding, severely impacting the Mylar membrane wrapping and casing processes. Therefore, the separator needs a double-sided adhesive structure, where the exposed cell forms a "hard brick"-like shape after hot pressing. In related technologies, adhesive layers are sprayed onto both sides of the base film, resulting in poor thickness consistency and potential misalignment of the exposed cell's tabs. While double-sided adhesive-coated separators offer significantly better thickness consistency between exposed cells, the winding process for sodium-ion batteries requires high thickness consistency within the separator roll. Although the adhesive dots on both sides of a double-sided adhesive-coated separator are arranged in a regular matrix, overlapping dots can cause thickness fluctuations. When both sides use the same regular dot matrix, the dots tend to overlap at specific locations, leading to localized thickness doubling. At the start of coating, adhesive dots are first applied to one surface of the separator. Then, by adjusting the initial position of the adhesive dots on the other surface, the dots on both surfaces can be completely overlapped. At this point, the separator thickness is the base film plus two layers of adhesive dots. This process can continue for tens of meters. However, during coating, equipment fluctuations or elastic deformation of the separator during coating can cause the adhesive dots on the second surface to shift, resulting in misalignment of the originally overlapped dots. In this case, the separator thickness is the base film plus one layer of adhesive dots. This process may continue for tens of meters before another fluctuation occurs, causing the dots to shift again, resulting in partial misalignment or re-overlapping. This manifests as irregular thickness fluctuations across the entire roll of separator, leading to uncontrolled tab gaps, tab misalignment, thinning of the cell, or cell deformation. Because these are caused by uncontrollable factors, the irregular separator thickness fluctuations cannot be easily offset by adjusting equipment process parameters. This problem occurs intermittently during the manufacturing process, severely impacting process yield.

[0075] Figure 10 This is a cross-sectional view of a diaphragm 400 according to an embodiment of this application. Figure 11 This is a plan view of the first adhesive layer 420 side of the diaphragm 400 according to an embodiment of this application. Figure 12 This is a plan view of the second adhesive layer 430 side of the diaphragm 400 according to an embodiment of this application. Figure 13 This is a plan view of the second adhesive layer 430 according to an embodiment of this application. Figure 14 This is a schematic diagram of the planar structure after the first adhesive layer 420 and the second adhesive layer 430 are stacked.

[0076] Please see Figures 10 to 14This application provides a diaphragm 400, which includes a base film 410, a first adhesive layer 420, and a second adhesive layer 430. The base film 410 has a first surface 411 and a second surface 412 disposed opposite to each other. The first adhesive layer 420 includes a plurality of first adhesive dots 4211 arrayed on the first surface 411. The second adhesive layer 430 includes a plurality of adhesive dot units 431, which are spaced apart on the second surface 412. Each adhesive dot unit 431 includes a plurality of second adhesive dots 4311 spaced apart. Each adhesive dot unit 431 has a plurality of second adhesive dots 4311 arranged along a first direction (e.g., ...). Figure 12 The distance between two adjacent second adhesive dots 4311 (as indicated by the middle arrow X) is arranged in a cosine sequence.

[0077] The term "multiple" means two or more. For example, the number of second adhesive dots 4311 that the adhesive dot unit 431 may include can be, but is not limited to, 10, 30, 50, 80, 100, 120, 150, 180, 200, etc.

[0078] It should be noted that the first surface 411 and the second surface 412 are arranged in the thickness direction of the base film 410 or the separator 400. The first adhesive layer 420, the base film 410 and the second adhesive layer 430 are stacked sequentially along the thickness direction of the separator 400.

[0079] It should be noted that, along the first direction, the spacing between two adjacent second adhesive dots 4311 is arranged in a cosine sequence, so that the second adhesive dots 4311 and the first adhesive dots 4211 periodically overlap along the first direction.

[0080] In some embodiments, the first adhesive layer 420 faces the positive electrode 310, and the second adhesive layer 430 faces the negative electrode 330. In other embodiments, the first adhesive layer 420 faces the negative electrode 330, and the second adhesive layer 430 faces the positive electrode 310.

[0081] The diaphragm 400 of this embodiment includes a base film 410, a first adhesive layer 420, and a second adhesive layer 430. The base film 410 has a first surface 411 and a second surface 412 disposed opposite to each other; the first adhesive layer 420 includes a plurality of first adhesive dots 4211 arranged in an array on the first surface 411; the second adhesive layer 430 includes a plurality of adhesive dot units 431, which are spaced apart on the second surface 412. Each adhesive dot unit 431 includes a plurality of second adhesive dots 4311 arranged at intervals. Along a first direction, the spacing between two adjacent second adhesive dots 4311 is arranged in a cosine sequence. This application arranges the spacing between two adjacent second adhesive dots 4311 along a first direction in each adhesive dot unit 431 in a cosine sequence. By actively controlling the overlap pattern of the first adhesive dot 4211 and the second adhesive dot 4311, the thickness variation of the separator 400 is offset at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. Furthermore, due to the regular overlap mechanism, it can be controllably adjusted by adjusting the parameters of the coating equipment. Even if fluctuations occur, the macroscopic stability is maintained due to the regular microscopic changes (i.e., periodic changes) in the overlap area. As a result, the thickness fluctuation of each roll of separator 400 is reduced. When the separator 400 is applied to a single cell 300, the thickness fluctuation of the core is greatly reduced, and the misalignment defect rate of the tabs (positive tab 313 and / or negative tab 333) of the single cell 300 is greatly reduced.

[0082] Please see Figures 12 to 14 In some embodiments, along the second direction (e.g.) Figure 12 As indicated by arrow Y, the spacing between two adjacent second adhesive dots 4311 is arranged in a sinusoidal sequence, wherein the first direction intersects the second direction.

[0083] Optionally, the first direction is perpendicular to the second direction.

[0084] In this embodiment, along the second direction, the spacing between two adjacent second adhesive dots 4311 is arranged in a sinusoidal sequence, thereby causing the second adhesive dots 4311 to periodically overlap with the first adhesive dots 4211 along the second direction. This cancels out the thickness variation of the separator 400 at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. Furthermore, due to the regular overlap mechanism, it can be controllably adjusted by adjusting the parameters of the coating equipment. Even if fluctuations occur, the macroscopic stability is maintained due to the regular microscopic changes (i.e., periodic changes) in the overlapping area. As a result, the thickness fluctuation of each roll of separator 400 is reduced. When the separator 400 is applied to a single cell 300, the thickness fluctuation of the core is greatly reduced, and the misalignment defect rate of the tabs (positive tab 313 and / or negative tab 333) of the single cell 300 is greatly reduced.

[0085] Please see Figure 11 and Figure 12 In some embodiments, the distance between the center point of the nth second adhesive dot 4311 and the center point of the (n+1)th second adhesive dot 4311 along the first direction is... x = γb × [1 + cos(2πn / N)], where γ is a constant, 0 < γ < 1, N is the number of second glue dots 4311 in each row along the first direction in the glue dot unit 431, and b is the distance between the center points of two adjacent first glue dots 4211, 1 ≤ n ≤ N-1.

[0086] Specifically, γ can be, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, etc.

[0087] Furthermore, 0.3≤γ≤0.6 can better reduce the thickness fluctuation of each roll of separator 400, so that when the separator 400 is applied to the single cell 300, it can better reduce the electrode misalignment defect rate and the thickness fluctuation of the core of the single cell 300.

[0088] In this embodiment, the distance between the center point of the nth second adhesive dot 4311 and the center point of the (n+1)th second adhesive dot 4311 along the first direction is... When x = γb × [1 + cos(2πn / N)], the second adhesive dot 4311 and the first adhesive dot 4211 can periodically overlap along the first direction, causing the thickness variation of the separator 400 to cancel each other out at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. This reduces the thickness fluctuation of each roll of separator 400. When the separator 400 is applied to a single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. Furthermore, due to the regular overlap mechanism, it can also be controllably adjusted by adjusting the parameters of the coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0089] Please see Figure 11 and Figure 12 In some embodiments, the distance between the center point of the m-th second adhesive dot 4311 and the center point of the (m+1)-th second adhesive dot 4311 along the second direction is... y = γb × [1 + sin(2πm / M)], where γ is a constant, 0 < γ < 1, M is the number of second glue dots 4311 in each column along the second direction in the glue dot unit 431, and b is the distance between the center points of two adjacent first glue dots 4211, 1 ≤ m ≤ M-1.

[0090] In this embodiment, the distance between the center point of the m-th second adhesive dot 4311 and the center point of the (m+1)-th second adhesive dot 4311 along the second direction is... When y = γb × [1 + sin(2πm / M)], the second adhesive dot 4311 and the first adhesive dot 4211 can periodically overlap along the second direction, causing the thickness variation of the separator 400 to cancel each other out at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. This reduces the thickness fluctuation of each roll of separator 400. When the separator 400 is applied to a single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. Furthermore, due to the regular overlap mechanism, it can also be controllably adjusted by adjusting the parameters of the coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0091] In some embodiments, the plurality of second adhesive dots 4311 in the adhesive dot unit 431 are arranged in M ​​rows and N columns; each row extends along a first direction and has N second adhesive dots 4311; each column extends along a second direction and has M second adhesive dots 4311; wherein, 6≤M≤100, 6≤N≤200.

[0092] Specifically, M can be, but is not limited to, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100. If M is too small, the second adhesive dots 4311 will be sparsely spaced, increasing the thickness fluctuation of the wound diaphragm 400 and the core, and increasing the misalignment rate of the core's tabs (positive tab 313 and / or negative tab 333). If M is too large, the second adhesive dots 4311 will be too dense, and the coverage of the second adhesive layer 430 will be too high, easily clogging the pores of the diaphragm 400 and reducing the ionic conductivity of the diaphragm 400.

[0093] Specifically, N can be, but is not limited to, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200. If N is too small, the second adhesive dots 4311 will be sparsely spaced, increasing the thickness fluctuation of the wound diaphragm 400 and the core, and increasing the misalignment rate of the core's tabs (positive tab 313 and / or negative tab 333). If N is too large, the second adhesive dots 4311 will be too dense, resulting in excessive coverage of the second adhesive layer 430, which can easily clog the pores of the diaphragm 400 and reduce the ionic conductivity of the diaphragm 400.

[0094] Furthermore, 3≤M≤50, 60≤N≤100. This allows the wound diaphragm 400 and the core to have smaller thickness fluctuations, the tabs of the core (positive tab 313 and / or negative tab 333) to have smaller misalignment rates, and the second adhesive layer 430 to have a suitable coverage, making it less likely to clog the diaphragm 400, and the diaphragm 400 to have higher ionic conductivity.

[0095] Please see Figure 11 and Figure 12 In some embodiments, the diaphragm 400 satisfies at least one of the following conditions: The equivalent circle diameter a1 of the first adhesive dot 4211 is in the range of 0.01mm≤a1≤5mm; The distance b between the center points of two adjacent first adhesive dots 4211 is in the range of: 0.01mm ≤ b ≤ 10mm; and The equivalent circle diameter a2 of the second adhesive dot 4311 is in the range of 0.01mm≤a2≤5mm.

[0096] The "equivalent circle diameter" refers to the diameter of a circle when the area of ​​an irregularly shaped two-dimensional figure is equivalent to the area of ​​a circle of the same area.

[0097] It should be noted that the equivalent circle diameter of the first glue dot portion 4211 and the equivalent circle diameter of the second glue dot portion 4311 can be the same or different.

[0098] Specifically, the equivalent circle diameter of the first adhesive dot portion 4211 can be, but is not limited to, 0.01mm, 0.05mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc. If the equivalent circle diameter of the first adhesive dot portion 4211 is too small, the coverage of the first adhesive layer 420 will be too low and the adhesion of the first adhesive layer 420 will be too low when the center point distance between adjacent first adhesive dots 4211 remains unchanged. This reduces the adhesion between the separator 400 and the positive electrode 310 or negative electrode 330, making the cross-section of the positive electrode 310 or negative electrode 330 prone to wrinkling, increasing the risk of purple spots and lithium plating in the single cell 300. If the equivalent circle diameter of the first adhesive dot portion 4211 is too large, the coverage of the first adhesive layer 420 will be too high when the center point distance between adjacent first adhesive dots 4211 remains unchanged. This can easily clog the pores of the separator 400 and reduce the ionic conductivity of the separator 400.

[0099] Understandably, along the first direction, the distance between the center points of two adjacent first adhesive dots 4211 ranges from 0.01 mm to 100 mm. Along the second direction, the distance between the center points of two adjacent first adhesive dots 4211 ranges from 0.01 mm to 100 mm.

[0100] Specifically, the distance b between the center points of two adjacent first adhesive dots 4211 can be, but is not limited to, 0.01mm, 0.05mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 3mm, 5mm, 8mm, 10mm, etc. If the distance b between the center points of two adjacent first adhesive dots 4211 is too small, the coverage of the first adhesive layer 420 will be too high, which will easily block the pores of the separator 400 and reduce the ionic conductivity of the separator 400. If the distance b between the center points of two adjacent first adhesive dots 4211 is too large, the coverage of the first adhesive layer 420 will be too low, and the adhesion of the first adhesive layer 420 will be too low, which will reduce the adhesion between the separator 400 and the positive electrode 310 or the negative electrode 330, making the cross-section of the positive electrode 310 or the negative electrode 330 prone to wrinkling, increasing the risk of purple spots and lithium plating in the single cell 300.

[0101] Specifically, the equivalent circle diameter of the second adhesive dot portion 4311 can be, but is not limited to, 0.01mm, 0.05mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc. If the equivalent circle diameter of the second adhesive dot portion 4311 is too small, the coverage of the second adhesive layer 430 will be too low and the adhesion of the second adhesive layer 430 will be too low when the center point distance between adjacent second adhesive dots 4311 remains unchanged. This reduces the adhesion between the separator 400 and the positive electrode 310 or negative electrode 330, making the cross-section of the positive electrode 310 or negative electrode 330 prone to wrinkling, increasing the risk of purple spots and lithium plating in the single cell 300. If the equivalent circle diameter of the second adhesive dot portion 4311 is too large, the coverage of the second adhesive layer 430 will be too high when the center point distance between adjacent second adhesive dots 4311 remains unchanged. This can easily clog the pores of the separator 400 and reduce the ionic conductivity of the separator 400.

[0102] In some embodiments, the plurality of second adhesive dots 4311 in the adhesive dot unit 431 are arranged in M ​​rows and N columns; each row extends along a first direction and has N second adhesive dots 4311; each column extends along a second direction and has M second adhesive dots 4311. The x-coordinate of the center point of the nth second adhesive dot 4311 in the m-th row along the first direction. for: ; The x-coordinate of the center point of the m-th second adhesive dot 4311 in the n-th column along the second direction for: .

[0103] In this embodiment, by making the distance between the center points of two adjacent second adhesive dots 4311 along the first direction follow a cosine sequence and the distance between the center points of two adjacent second adhesive dots 4311 along the second direction follow a sine sequence, the second adhesive dots 4311 and the first adhesive dots 4211 periodically overlap. This causes the thickness variation of the separator 400 to cancel each other out at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. Consequently, the thickness fluctuation of each roll of separator 400 is reduced. When the separator 400 is applied to a single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. Furthermore, due to the regular overlap mechanism, it can also be controllably adjusted by adjusting the parameters of the coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0104] In some embodiments, the orthographic projection of the first adhesive dot 4211 onto the first surface 411 is at least one of a circle, a near-circular shape, a polygon, or an annulus. The orthographic projection of the second adhesive dot 4311 onto the second surface 412 is at least one of a circle, a near-circular shape, a polygon, or an annulus.

[0105] Figure 15 This is a schematic diagram of the structure of a dotting roller 500 according to an embodiment of this application.

[0106] Please see Figure 15 This application also provides a dotting roller 500, which includes a roller shaft 510 and at least one dotting unit 520a. The roller shaft 510 has an axial direction and a circumferential direction; each dotting unit 520a includes a plurality of dotting portions 520, which surround the roller shaft 510 in the axial direction (e.g., ...). Figure 15 (as indicated by arrow X') and circumferential direction (as shown) Figure 15 (As indicated by arrow Y') The spacing is arranged at intervals; along the axial direction of the roller 510, the spacing between two adjacent dot coating portions 520 is arranged in a cosine sequence.

[0107] It should be noted that the dotting roller 500 can be used for dotting the second adhesive layer 430 of the diaphragm 400.

[0108] Optionally, the number of dotting units 520a on the dotting roller 500 can be 1, 2, 3, 4, 5, 8, 10, 15, 20, 30, etc.

[0109] In this embodiment, along the axial direction of the roller 510, the spacing between two adjacent dot-coating portions 520 is arranged in a cosine sequence. Therefore, when the dot-coating roller 500 is used to dot-coat the second adhesive layer 430 of the separator 400, the spacing between two adjacent second adhesive dots 4311 along the first direction is arranged in a cosine sequence. This causes the second adhesive dots 4311 and the first adhesive dots 4211 to periodically overlap along the first direction, so that the thickness variation of the separator 400 is canceled out at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. This reduces the thickness fluctuation of each roll of separator 400. When the separator 400 is applied to the single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. In addition, since it is a regular overlap mechanism, it can also be controllably adjusted by adjusting the parameters of the dot-coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0110] In some embodiments, the spacing between two adjacent dotting portions 520 is arranged in a sinusoidal sequence along the circumferential direction of the roller 510.

[0111] In this embodiment, the spacing between two adjacent dot-coating portions 520 along the circumferential direction of the roller 510 is arranged in a sinusoidal sequence. Therefore, when the dot-coating roller 500 is used to dot-coat the second adhesive layer 430 of the separator 400, the spacing between two adjacent second adhesive dots 4311 along the second direction is arranged in a sinusoidal sequence. This causes the second adhesive dots 4311 and the first adhesive dots 4211 to periodically overlap along the second direction, so that the thickness variation of the separator 400 is canceled out at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. This reduces the thickness fluctuation of each roll of separator 400. When the separator 400 is applied to the single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. In addition, since it is a regular overlapping mechanism, it can also be controlled by adjusting the parameters of the dot-coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0112] In some embodiments, the dotting roller 500 is used for the second adhesive layer 430 of the diaphragm 400 in this application embodiment; along the axial direction, the distance between the center point of the k1'th dotting portion 520 and the (k1'+1)th dotting portion 520 is... x'=γ'b×[1+cos(2πk1' / N')], where γ' is a constant, 0<γ'<1, N' is the number of dots 520 in each row along the axial direction, b is the distance between the center points of two adjacent first adhesive dots 4211 of the diaphragm 400, 0.01mm≤b≤100mm, 1≤k1'≤N'-1.

[0113] Specifically, γ can be, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, etc. Furthermore, 0.4 ≤ γ' ≤ 0.6, which can better reduce the thickness fluctuation of each roll of separator 400, thus improving the electrode misalignment defect rate and core thickness fluctuation of the single cell 300 when the separator 400 is applied.

[0114] In this embodiment, the distance between the center point of the k1'th dot-coating part 520 and the (k1'+1)th dot-coating part 520 along the axial direction is... When x'=γ'b×[1+cos(2πk1' / N')], when the dot-coating roller 500 is used to prepare the second adhesive layer 430 of the separator 400, the second adhesive dot portion 4311 of the separator 400 and the first adhesive dot portion 4211 periodically overlap along the first direction, so that the thickness variation of the separator 400 is canceled at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. This reduces the thickness fluctuation of each roll of separator 400. When the separator 400 is applied to the single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. In addition, since it is a regular overlap mechanism, it can also be controlled by adjusting the parameters of the dot-coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0115] In some embodiments, along the circumferential direction, the distance between the center point of the k2'th dotted part 520 and the (k2'+1)th dotted part 520 is... y'=γ'b×[1+sin(2πk2' / M')], where M' is the number of dots 520 in each circle along the circumferential direction, 1≤k2'≤M'-1.

[0116] In this embodiment, the distance between the center point of the k2'th dot-coating part 520 and the (k2'+1)th dot-coating part 520 along the circumferential direction is... When y'=γ'b×[1+sin(2πk2' / M')], when the dot-coating roller 500 is used to prepare the second adhesive layer 430 of the separator 400, the second adhesive dot portion 4311 of the separator 400 and the first adhesive dot portion 4211 periodically overlap along the second direction, so that the thickness variation of the separator 400 is canceled at the microscale, avoiding macroscopic fluctuations in the thickness of the separator 400. This reduces the thickness fluctuation of each roll of separator 400. When the separator 400 is applied to the single cell 300, the thickness fluctuation of the core is greatly reduced, and the electrode misalignment defect rate of the single cell 300 is greatly reduced. In addition, since it is a regular overlap mechanism, it can also be controlled by adjusting the parameters of the dot-coating equipment, thereby better controlling the thickness fluctuation of the separator 400, the thickness fluctuation of the core, and the electrode misalignment defect rate.

[0117] Optionally, the equivalent circle diameter a2' of the dotting part 520 is in the range of 0.01mm ≤ a2' ≤ 5mm. Specifically, the equivalent circle diameter a2' of the dotting part 520 can be, but is not limited to, 0.01mm, 0.05mm, 0.1mm, 0.3mm, 0.5mm, 0.8mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc. If the equivalent circle diameter a2' of the dot-coating portion 520 is too small, the coverage of the second adhesive layer 430 of the separator 400 will be too low, and the adhesion of the second adhesive layer 430 will be too low, reducing the adhesion between the separator 400 and the positive electrode 310 or the negative electrode 330. This will make the cross-section of the positive electrode 310 or the negative electrode 330 prone to wrinkling, increasing the risk of purple spots and lithium plating in the single cell 300. If the equivalent circle diameter a2' of the dot-coating portion 520 is too large, the coverage of the second adhesive layer 430 of the separator 400 will be too high, which will easily clog the pores of the separator 400 and reduce the ionic conductivity of the separator 400, while keeping the center-to-center distance between adjacent second adhesive dots 4311 unchanged.

[0118] In some embodiments, the shape of the dotting portion 520 is at least one of a circle, a near-circular shape, a polygon, or a ring.

[0119] Optionally, the dotting portion 520 may be, but is not limited to, a protrusion or a groove.

[0120] Optionally, the dotting portion 520 is a protruding post, and the height of the protruding post ranges from 0.3mm to 3mm. Specifically, the height of the protruding post can be, but is not limited to, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.3mm, 1.5mm, 1.8mm, 2.0mm, 2.3mm, 2.5mm, 2.8mm, 3mm, etc.

[0121] Optionally, the dotting portion 520 is a groove, and the depth of the groove ranges from 0.3mm to 3mm. Specifically, the depth of the groove can be, but is not limited to, 0.3mm, 0.5mm, 0.8mm, 1.0mm, 1.3mm, 1.5mm, 1.8mm, 2.0mm, 2.3mm, 2.5mm, 2.8mm, 3mm, etc.

[0122] Optionally, the number N' of each dotting portion 520 in each row along the axial direction of each dotting unit is in the range of 6 ≤ N' ≤ 200. Specifically, N' can be, but is not limited to, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200. If N' is too small, the second adhesive dot portion 4311 of the diaphragm 400 produced by the dotting roller 500 will be relatively sparse, which will increase the thickness fluctuation of the wound diaphragm 400 and the core, and increase the misalignment rate of the core's tabs (positive tab 313 and / or negative tab 333). If N' is too large, the second adhesive dots 4311 of the diaphragm 400 produced by the dotting roller 500 will be too dense, and the coverage of the second adhesive layer 430 will be too high, which will easily block the pores of the diaphragm 400 and reduce the ionic conductivity of the diaphragm 400.

[0123] Optionally, the number M' of each dotting unit in the circumferential direction, in each circle, ranges from 6 ≤ M' ≤ 100. Specifically, M' can be, but is not limited to, 6, 8, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100. If M' is too small, the second adhesive dots 4311 of the diaphragm 400 produced by the dotting roller 500 will be relatively sparse, which will increase the thickness fluctuation of the wound diaphragm 400 and the core, and increase the misalignment rate of the core's tabs (positive tab 313 and / or negative tab 333). If M' is too large, the second adhesive dots 4311 of the diaphragm 400 produced by the dotting roller 500 will be too dense, the coverage of the second adhesive layer 430 will be too high, which will easily clog the pores of the diaphragm 400 and reduce the ionic conductivity of the diaphragm 400.

[0124] Furthermore, 3≤M'≤50, 60≤N'≤100. This allows the diaphragm 400, after being made using the dot-coating roller 500, to have smaller thickness fluctuations after being wound and formed into a core. The tabs (positive tab 313 and / or negative tab 333) of the core have a smaller misalignment rate, and the second adhesive layer 430 has a suitable coverage, making it less likely to clog the diaphragm 400. The diaphragm 400 also has a higher ionic conductivity.

[0125] The diaphragm 400 of this application will be further described below through specific embodiments.

[0126] Examples 1 to 13 The diaphragm 400 and the core of each embodiment are prepared by the following steps: (1) Preparation of diaphragm 400: A base membrane 410 is provided, the base membrane 410 having a thickness of 7 μm and a width of 100 mm along a first direction; a first adhesive layer 420 is dotted on a first surface 411 of the base membrane 410, and a second adhesive layer 430 is dotted on a second surface 412 of the base membrane 410; the first adhesive layer 420 includes a plurality of first adhesive dots 4211 arranged in an array, the first adhesive dots 4211 being circular, the diameter of the first adhesive dots 4211 being a1 = 1.0 mm, and the diameter of two adjacent first adhesive dots 4211 being a1 = 1.0 mm. The distance between the center points is b = 1.5 mm; the thickness of the first adhesive dot portion 4211 is 1 μm; the second adhesive layer 430 includes a plurality of adhesive dot units 431 arranged at intervals, each adhesive dot unit 431 including a plurality of second adhesive dot portions 4311 arranged at intervals, the second adhesive dot portions 4311 are circular, the diameter of the second adhesive dot portion 4311 is a2 = 1.0 mm, and the thickness of the second adhesive dot portion 4311 is 1 μm; along the first direction, the distance between the center points of the nth second adhesive dot portion 4311 and the (n+1)th second adhesive dot portion 4311 is... x = γb × [1 + cos(2πn / N)]; along the second direction, the distance between the center point of the m-th second adhesive dot 4311 and the center point of the (m+1)-th second adhesive dot 4311. y = γb × [1 + sin(2πm / M)], 1 ≤ n ≤ N-1, 1 ≤ m ≤ M-1. The M, N, and γ of the diaphragm 400 in each embodiment are shown in Table 1 below. The diaphragm 400 in each embodiment can be made using a dotting roller 500 with a diameter of 60 mm and a length of 100 mm.

[0127] (2) Preparation of positive electrode 310: The positive electrode active material is polyanionic sulfate Na 2.4 Fe 1.8 (SO4)3, conductive carbon black (Super-P), and binder PVDF are mixed at a mass ratio of 97:1:2; then N-methylpyrrolidone (NMP) is added as a solvent and stirred evenly to prepare a positive electrode slurry with a solid content of 60wt%. The positive electrode slurry is then uniformly coated on one surface of a 11μm thick positive electrode current collector 311 aluminum foil and dried at 85℃. The above steps are then repeated on the other surface of the positive electrode 310. After rolling, a positive electrode 310 with a positive active layer 312 coated on both sides is obtained; the single-sided thickness of the positive active layer 312 is 80μm.

[0128] (3) Preparation of negative electrode sheet 330: The negative electrode active material hard carbon, conductive carbon black (Super-P) and sodium carboxymethyl cellulose (CMC-Na) and styrene-butadiene rubber (SBR) are mixed in a mass ratio of 97:1:1.5:0.5, deionized water is added, and the mixture is stirred evenly to prepare a negative electrode slurry with a solid content of 55wt%. Then, the negative electrode slurry is uniformly coated on one surface of a negative electrode current collector 331 aluminum foil with a thickness of 11μm, and dried at 105℃. Then, the above steps are repeated on the other surface of the negative electrode sheet 330. After rolling, a negative electrode sheet 330 with a negative electrode active layer 332 coated on both sides is obtained. The single-sided thickness of the negative electrode active layer 332 is 70μm.

[0129] (4) Core preparation: The positive electrode 310, separator 400 and negative electrode 330 prepared above are arranged in order, so that the separator 400 is between the positive electrode 310 and the negative electrode 330 to play a role in isolation (and the first adhesive layer 420 faces the positive electrode 310 and the second adhesive layer 430 faces the negative electrode 330). The core length is 100mm and the width is 10mm. The positive electrode 310 has 10 layers and the separator 400 has 24 layers. When winding, it is wound along the second direction; the electrode assembly is obtained, and the electrode assembly is wound to obtain the core.

[0130] Example 14 The difference between the diaphragm 400 in this embodiment and that in embodiment 1 is that the second adhesive layer 430 in this embodiment is shifted 0.5 mm along the first direction and 0.5 mm along the second direction compared to that in embodiment 1.

[0131] Examples 15 to 22 The difference between each embodiment and embodiment 4 is that the distance b between the center points of two adjacent first adhesive dots 4211 is different.

[0132] Comparative Example 1 The diaphragm 400 of Comparative Example 1 includes a first adhesive layer 420, a base film 410, and a second adhesive layer 430 stacked together. The thickness of the base film 410 is 7 μm. The first adhesive layer 420 includes a plurality of first adhesive dots 4211 arranged in an array. The first adhesive dots 4211 are circular, with a diameter a1 = 1.0 mm and a distance b = 1.5 mm between the center points of two adjacent first adhesive dots 4211. The second adhesive layer 430 includes a plurality of second adhesive dots 4311 arranged in an array. The second adhesive dots 4311 are circular, with a diameter of 1.0 mm and a distance 1.5 mm between the center points of two adjacent second adhesive dots 4311.

[0133] The diaphragm 400 and the winding core of each embodiment and comparative example were subjected to the following performance tests: (1) Thickness fluctuation test of each roll of diaphragm 400: Take a sample of each 1m of the diaphragm of each embodiment and comparative example, measure the thickness (take ≥5 points at intervals and take the average value), collect the thickness fluctuation, thickness fluctuation = (sample thickness - diaphragm design thickness value) / 1m.

[0134] (2) Specifications and measurement method for misalignment of the tabs (positive tab 313 and / or negative tab 333) of the core: Tab misalignment refers to the tab alignment. If the tab misalignment specification exceeds the standard, it will increase the scrap loss of the core on the one hand; on the other hand, poor alignment will have an adverse effect on the tab welding (some tabs cannot be welded or the welding area is small, which will cause some positive tabs 310 / negative tabs 330 to be unable to conduct electricity, resulting in invalid positive tabs 310 / negative tabs 330 and increasing the difficulty of ultrasonic welding). The tab misalignment specification of the core must meet the following 4 conditions at the same time: ① Distance from the first positive tab 313 to the edge of the core: A±4mm; ② Distance from the first negative tab 333 to the edge of the core: B±4mm; ③ Distance from the innermost tab to the edge of the core: ≤[(A+B) / 2+54]mm; ④ Distance from the outermost tab to the edge of the core: ≥[(A+B) / 2-7.5]mm. Where A and B are both natural numbers, and 15≤A≤35, 15≤B≤35.

[0135] The calculation method for the tab misalignment defect rate is as follows: 300 cores are wound in each group, and the number of misaligned cores is calculated separately. The defect rate for 1 misalignment is 1 / 300 × 100% = 0.33%, and the defect rate for 2 misalignments is 2 / 300 × 100% = 0.67%. Under normal circumstances, the lower the tab misalignment defect rate, the better; for normal mass production, it should be ≤1%.

[0136] (3) Core thickness fluctuation test: The length of the wound core is 100mm, the width is 10mm, and the diaphragm is 50 layers; the average thickness of the three cores is measured, and the core thickness fluctuation = (average core thickness - core design thickness) / 50 layers.

[0137] The performance parameters of the diaphragm 400 and the core of each embodiment and comparative example are shown in Table 1 below.

[0138] Table 1 Performance parameters of diaphragm 400 in Examples 1 to 22 and Comparative Example 1

[0139] As can be seen from the test results of Example 1 and Comparative Example 1, compared with the arrangement of multiple first adhesive dots 4211 in the first adhesive layer 420 and multiple second adhesive dots 4311 in the second adhesive layer 430 in Comparative Example 1, the arrangement of multiple first adhesive dots 4211 in the first adhesive layer 420 and multiple second adhesive dots 4311 in the second adhesive layer 430 with the spacing between the center points of adjacent second adhesive dots 4311 along the first direction being cosine and the spacing between the center points of adjacent second adhesive dots 4311 along the second direction being sine can better reduce the thickness fluctuation of each roll of diaphragm 400, reduce the thickness fluctuation of the core, and greatly reduce the tab misalignment rate of the core.

[0140] The test results of Examples 1 to 6 show that as the values ​​of M and N in the adhesive dot unit 431 increase, the thickness fluctuation of each roll of diaphragm 400 gradually decreases, the thickness fluctuation of the core also gradually decreases, and the misalignment rate of the core's tabs gradually decreases. When the values ​​of M and N reach a certain value, further increases in M ​​and N cause the thickness fluctuation of each roll of diaphragm 400, the thickness fluctuation of the core, and the misalignment rate of the core's tabs to gradually stabilize.

[0141] The test results from Examples 2, 7 to 13 show that as γ increases, the thickness fluctuation of each roll of diaphragm 400 first gradually decreases and then gradually increases, while the thickness fluctuation of the core gradually increases. The misalignment of the core's tabs first gradually decreases and then gradually increases. When 0.3 ≤ γ ≤ 0.6, the thickness fluctuation of each roll of diaphragm 400 is smaller, the thickness fluctuation of the core is smaller, and the misalignment rate of the core's tabs is smaller.

[0142] As can be seen from the test results of Examples 1 and 14, after the second adhesive layer is translated, the resulting diaphragm 400 is wound up, and the fluctuation of each roll of diaphragm 400, the thickness fluctuation of the core, and the misalignment rate of the core tabs are all low.

[0143] As can be seen from the test results of Examples 2, 15 to 22, as the distance between the center points of two adjacent first adhesive dots 4211 increases, the thickness fluctuation of each roll of diaphragm 400 gradually increases, the thickness fluctuation of the core also gradually increases, and the electrode misalignment rate of the core also shows an increasing trend.

[0144] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0145] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A diaphragm, characterized by The diaphragm includes: The base film has a first surface and a second surface disposed opposite to each other; A first adhesive layer, the first adhesive layer comprising a plurality of first adhesive dots arranged in an array on the first surface; and The second adhesive layer includes a plurality of adhesive dot units, which are spaced apart on the second surface. Each adhesive dot unit includes a plurality of second adhesive dot portions spaced apart. The distance between two adjacent second adhesive dot portions in each adhesive dot unit along a first direction is arranged in a cosine sequence.

2. The separator of claim 1, wherein Along the second direction, the spacing between two adjacent second adhesive dots is arranged in a sinusoidal sequence, wherein the first direction intersects the second direction.

3. The diaphragm of claim 2, wherein In the first direction, the distance between the center points of the n-th second glue point part and the (n+1)-th second glue point part x = γb × [1 + cos(2πn / N)], where γ is a constant, 0 < γ < 1, N is the number of second glue point parts in each row in each of the glue point units in the first direction, b is the distance between the center points of two adjacent first glue point parts, 1 ≤ n ≤ N-1.

4. The diaphragm of claim 2, wherein In the second direction, the distance between the center points of the mth second glue point part and the (m+1)th second glue point part y = γb x [1 + sin(2πm / M)], where γ is a constant, 0 < γ < 1, M is the number of second glue point parts in each column in each glue point unit in the second direction, b is the distance between the center points of two adjacent first glue point parts, 1 ≤ m ≤ M-1.

5. The separator of claim 1, wherein The plurality of second adhesive dots in the adhesive dot unit are arranged in M ​​rows and N columns; each row extends along a first direction and each row has N second adhesive dots. Each column extends along the second direction, and each column has M second adhesive dots; wherein, 6≤M≤100, 6≤N≤200.

6. The separator according to any one of claims 1 to 5, wherein The diaphragm satisfies at least one of the following conditions: The equivalent circle diameter a1 of the first adhesive dot portion is in the range of: 0.01mm≤a1≤5mm; The distance b between the center points of two adjacent first adhesive dots is in the range of: 0.01mm ≤ b ≤ 10mm; and The equivalent circle diameter a2 of the second adhesive dot is in the range of 0.01mm≤a2≤5mm.

7. The separator of claim 1, wherein The plurality of second adhesive dots in the adhesive dot unit are arranged in M ​​rows and N columns; each row extends along a first direction and each row has N second adhesive dots. Each column extends along the second direction, and each column has M second adhesive dots; Xm(n) = Xm(n-1) + (Xm+1(n) - Xm(n-1)) / 2 is: ; X-coordinate of the center point of the mth second adhesive dot part in the nth column in the second direction is: .

8. A spotter roller characterized by, The dotting roller includes: A roller shaft having an axial direction and a circumferential direction; and At least one dotting unit, each dotting unit including multiple dotting sections, the multiple dotting sections being spaced apart in the axial and circumferential directions around the roller shaft; along the axial direction of the roller shaft, the spacing between two adjacent dotting sections is arranged in a cosine sequence.

9. The spotter roller of claim 8, wherein, Along the circumferential direction of the roller shaft, the spacing between two adjacent dots is arranged in a sinusoidal sequence.

10. The spotter roller according to claim 8 or 9, characterized in that The dotting roller is used to prepare the second adhesive layer of the diaphragm according to any one of claims 1-7; The distance between the center point of the k1th point coating part and the center point of the (k1+1)th point coating part in the axial direction x' = γ' b × [1 + cos(2πk1' / N')] where γ' is a constant, 0 < γ' < 1, N' is the number of the point coating parts in each row in the axial direction, b is the distance between the center points of two adjacent first glue point parts of the diaphragm, 0.01 mm ≤ b ≤ 100 mm, and 1 ≤ k1' ≤ N'-1.

11. The spotter roller of claim 10, wherein, A distance between a center point of the k2th point coating part and a center point of the (k2+1)th point coating part in the circumferential direction y' = γ' b x [1 + sin(2πk2' / M')], where M' is a number of point coating parts per one turn in the circumferential direction, 1 ≤ k2' ≤ M' - 1.

12. A single cell, characterized by The single cell includes a positive electrode, a separator as described in any one of claims 1-7, a negative electrode, and an electrolyte, wherein the separator is located between the positive electrode and the negative electrode.

13. An energy storage device, characterized by, The energy storage device includes one or more single-cell batteries as described in claim 12.

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