Protective tape, single battery, energy storage device and power system

Abstract

The application provides a protective tape, a single battery, an energy storage device and an electric system. The protective tape comprises an isolation substrate, the isolation substrate has a plurality of pores, the pores are nanoscale in size; a heat insulation coating is arranged on the surface of the isolation substrate; and a bonding glue layer is arranged on the surface of the heat insulation coating away from the isolation substrate; the protective tape has a plurality of channels arranged at intervals, the channels respectively penetrate through the opposite two surfaces of the protective tape along the thickness direction, and the radial size of the channels is micrometer in size.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a protective tape, a single cell, an energy storage device, and an electrical system. Background Technology

[0002] The active material layer of the battery electrode sheets (including positive and negative electrode sheets) is usually brittle and lacks toughness. For wound cells, the corners of the innermost few turns of the electrode sheets are subjected to greater pressure deformation and bending, and the active material layer is very easy to break and fall off. These foreign particles can easily increase the failure rate of the insulation withstand voltage test (Hi-pot), causing the wound cells to be scrapped and greatly affecting the yield of mass production.

[0003] In related technologies, polyimide tape (PI tape) or polypropylene blue adhesive (PP blue adhesive) is placed at the corners of the wound battery cell to prevent cracks, breakage, and powder shedding from occurring during the cold pressing process after winding the electrode sheet. While this can alleviate the tip discharge effect of foreign particles under high voltage during Hi-pot testing, thus improving particle breakdown and Hi-pot defects, ions cannot pass through the PI tape and PP blue adhesive. This means that the area on the active material layer of the electrode sheet with the PI tape or PP blue adhesive does not participate in the charge-discharge cycle reaction, resulting in a 100% loss of active capacity in this area (approximately 0.3Ah-0.5Ah). This wastes active material and reduces the battery's cycle performance. Summary of the Invention

[0004] This application provides a protective tape that has ion-conducting properties and high electrolyte wettability. When applied to a single battery cell, it can reduce the capacity loss of the single battery cell.

[0005] In a first aspect, embodiments of this application provide a protective tape, the protective tape comprising: An isolation substrate having multiple pores of nanoscale size; A heat-insulating coating, wherein the heat-insulating coating is disposed on the surface of the insulating substrate; and An adhesive layer is disposed on the surface of the heat-insulating coating opposite to the insulating substrate; The protective tape has a plurality of channels spaced apart, each channel penetrating two opposite surfaces of the protective tape along its thickness direction, and the radial dimension of the channels is on the order of micrometers.

[0006] Furthermore, the radial dimension w of the channel is in the range of 0.5μm≤w≤15μm.

[0007] Furthermore, the spacing s between two adjacent channels is in the range of 100μm≤s≤400μm.

[0008] Furthermore, the distribution density of the channels ranges from 500 channels / cm² to 10,000 channels / cm².

[0009] Furthermore, the heat-insulating coating comprises ceramic particles and toughening fibers, wherein the toughening fibers are dispersed in the ceramic particles; and the mass fraction of the toughening fibers in the heat-insulating coating ranges from 15 wt% to 35 wt%.

[0010] Furthermore, the heat-insulating coating satisfies at least one of the following conditions: The average diameter of the toughening fibers ranges from 0.2 μm to 2 μm; The average aspect ratio of the toughening fiber ranges from 20 to 200; The toughening fiber includes at least one of aramid fiber, polyimide fiber, and polyacrylonitrile fiber; and The median particle size Dv50 of the ceramic particles ranges from 0.3 μm to 1.0 μm.

[0011] Furthermore, the adhesive layer includes a plurality of bonding points spaced apart on the surface of the heat-insulating coating away from the insulating substrate, and the glass transition temperature of the adhesive layer is less than or equal to 30°C.

[0012] Furthermore, the electrolyte wetting distance on the side of the protective tape having the adhesive layer is greater than or equal to 50 mm. The electrolyte wetting distance refers to the diffusion distance of the electrolyte along the length of the protective tape after 1 minute when 0.5 mL of electrolyte is dropped onto the side of the protective tape with the adhesive layer and a size of 5 mm × 200 mm.

[0013] Furthermore, the protective tape satisfies at least one of the following conditions: The puncture strength of the protective tape is greater than or equal to 400 gf; The surface elastic modulus E of the adhesive layer side of the protective tape is in the range of 600MPa≤E≤2000MPa; and The air permeability of the protective tape ranges from 10s / 100cc to 50s / 100cc.

[0014] Secondly, embodiments of this application also provide a single-cell battery, the single-cell battery including a core, the core including a positive electrode, a separator, a negative electrode, the protective tape described in the embodiments of this application, and an electrolyte, the separator being disposed between the positive electrode and the negative electrode, the positive electrode, the separator and the negative electrode being stacked and wound so that the core has a wound structure, the protective tape being disposed on the surface of at least one of the positive electrode and the negative electrode facing the separator, and located at the corner of the core, the adhesive surface of the protective tape facing the positive electrode or the negative electrode.

[0015] Thirdly, 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.

[0016] Fourthly, embodiments of this application also provide an electrical system, the electrical system comprising: Electrical equipment; and The energy storage device described in this application embodiment is used to supply power to the electrical equipment.

[0017] The protective tape in this embodiment includes an insulating substrate, a heat-insulating coating, and an adhesive layer. The insulating substrate has pores of nanoscale size, which gives the protective tape ion-conducting properties, allowing metal ions (such as lithium ions and sodium ions) to pass through. When the protective tape is applied to the corner of the core, the corner can still participate in charge-discharge cycles. Compared to the PI tape and PP blue adhesive used in related technologies, this significantly reduces capacity loss at the adhesive application point of the battery core and increases the capacity of the battery. However, since the corner of the core has both a separator and a protective tape, the ion transport path at the location of the protective tape is longer (it needs to pass through both the separator and the protective tape). This increases the interfacial impedance of the core, increases resistance to ion migration, reduces the ionic conductivity at the corner, and consequently reduces the cycle performance of the battery. This application improves the surface roughness of the protective tape by creating micron-sized pores, making it easier for the electrolyte to spread and penetrate. This not only reduces the air permeability of the protective tape but also significantly improves its electrolyte wettability. Consequently, it can better wet the separator and protective tape at the corners of the core, increasing the ionic conductivity at the corners of the core, avoiding uneven internal resistance of individual cells, and improving the cycle life of individual cells. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application.

[0022] Figure 4 This is a schematic diagram of the structure of an electrical system according to an embodiment of this application.

[0023] Figure 5 This is a schematic diagram of the structure of an energy storage device according to an embodiment of this application.

[0024] Figure 6 This is a schematic diagram of the structure of a single battery cell according to an embodiment of this application.

[0025] 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.

[0026] Figure 8 This is a cross-sectional view of a protective tape according to an embodiment of the application.

[0027] Figure 9 This is a cross-sectional view of a protective tape according to yet another embodiment of the application.

[0028] 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-storage-charging station, 170-Automobile, 200-Energy storage device, 100'-Power system, 110'-Power equipment, 300-Single cell, 310-Core, 311-Positive electrode sheet, 312-Separator, 313-Negative electrode sheet, 340-Housing shell, 341-Receiving cavity, 350-End cap assembly, 400-Protective tape, 401-Channel, 410-Insulating substrate, 420-Heat insulation coating, 430-Adhesive layer, 431-Adhesive point. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 the energy storage scenario on the generation / distribution side.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Figure 4 This is a schematic diagram of the structure of an electrical system 100' according to an embodiment of this application.

[0046] 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.

[0047] Optionally, the electrical equipment 110' can be, but is not limited to, at least one of the following: power grid, base station, power station, charging station, household appliances (such as air conditioner, refrigerator, washing machine, lighting equipment, etc.).

[0048] Optionally, the electrical equipment 110' and the energy storage device 200 can be electrically connected via a high-voltage cable 140.

[0049] 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.

[0050] Optionally, the energy storage device 200 includes one or more individual battery cells 300.

[0051] 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. 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 to be achieved by the energy storage device 200.

[0052] 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 systems, and is also applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0053] Optionally, the energy storage device 200 may include, but is not limited to, battery integrated systems such as single-cell batteries, or battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage containers, etc. In other words, when the energy storage device 200 includes a single-cell battery 300, the energy storage device 200 can exist in the form of a single-cell battery 300. When the energy storage device 200 includes multiple single-cell batteries 300, the multiple single-cell batteries 300 can 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; 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 can be, but is not limited to, the listed products, and can also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 200. This application embodiment only illustrates the case where the energy storage device 200 is a multi-cell battery (i.e., multiple single-cell batteries 300).

[0054] Optionally, the single cell 300 can be, but is not limited to, at least one of cylindrical, square, prismatic, or other shaped cells.

[0055] 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.

[0056] 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.

[0057] 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 provided. Figure 6 A schematic diagram of the cross-sectional structure along the AA direction.

[0058] Please see Figure 6 and Figure 7 This application provides a single-cell battery 300, which includes a core 310. The core 310 includes a positive electrode 311, a separator 312, a negative electrode 313, a protective tape 400, and an electrolyte. The separator 312 is disposed between the positive electrode 311 and the negative electrode 313. The positive electrode 311, the separator 312, and the negative electrode 313 are stacked and wound to form a wound structure for the core 310. The protective tape 400 is disposed on the surface of at least one of the positive electrode 311 and the negative electrode 313 facing the separator 312 and is located at a corner of the core 310.

[0059] Understandably, the positive electrode 311 and the negative electrode 313 are located on opposite sides of the separator 312, that is, the separator 312 is located between the positive electrode 311 and the negative electrode 313, separating the positive electrode 311 and the negative electrode 313.

[0060] It should be noted that the positive electrode 311 is in a wound state, the separator 312 is in a wound state, and the negative electrode 313 is in a wound state. That is to say, the positive electrode 311, the separator 312, and the negative electrode 313 are stacked in a preset order and then wound together to form a wound core 310 (also known as a wound cell).

[0061] "Corner" refers to the bend in the coil when the positive electrode 311, diaphragm 312 and negative electrode 313 are stacked in a preset order and then wound.

[0062] Understandably, the single cell 300 of this application is a wound cell.

[0063] It should be noted that the positive electrode 311, the separator 312, the negative electrode 313, and the protective tape 400 are all at least partially immersed in the electrolyte.

[0064] It should be noted that the positive electrode 311 and the negative electrode 313 can be collectively referred to as electrode plates.

[0065] It should be noted that the surface of the positive electrode 311 facing the separator 312 may be provided with protective tape 400; the surface of the negative electrode 313 facing the separator 312 may also be provided with protective tape 400; or both the positive electrode 311 and the negative electrode 313 facing the separator 312 may be provided with protective tape 400.

[0066] It should also be noted that the positive electrode 311 and / or the negative electrode 313 may have a protective tape 400 on one of their surfaces, or both of their opposite surfaces may have a protective tape 400. That is, the positive electrode 311 may have a protective tape 400 on one surface or both of its opposite surfaces, and the negative electrode 313 may have a protective tape 400 on one surface or both of its opposite surfaces.

[0067] Optionally, the protective tape 400 can be located near the innermost coil of the winding. For example, counting from the inside out, the protective tape 400 is provided at the positions of the first to the fifth coils of the core 310.

[0068] Optionally, the number of protective tapes 400 can be one or more. The number of protective tapes 400 can be, for example, but not limited to, 1, 2, 4, 5, 8, 10, 15, 20, etc. The term "multiple" means two or more.

[0069] The single-cell battery 300 of this application has a protective tape 400 on the surface of at least one of the positive electrode 311 and the negative electrode 313 facing the separator 312, and the tape is also provided at the corner of the core 310. This is equivalent to setting up a double physical barrier at the corner of the core 310. If one layer fails due to impurities, dendrite punctures, or localized thermal shrinkage, the other layer can still prevent the positive electrode 311 and the negative electrode 313 from directly contacting each other, significantly reducing the risk of short circuit in the single-cell battery 300. In addition, after the double-layer film of separator 312 and protective tape 400 is provided at the corner of the core 310, higher heat is required to shrink both layers of film simultaneously. Under high temperature conditions, it is less likely to shrink and fail over a large area, delaying thermal runaway and improving the safety of the single-cell battery 300.

[0070] 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 form a closed receiving cavity 341 for housing the electrolyte, the positive electrode 311, the separator 312, and the negative electrode 313. Understandably, the end cap assembly 350 electrically connects the positive electrode 311 and the negative electrode 313, leading them out for electrical connection to external devices or other single-cell batteries 300.

[0071] The active material layer of the battery electrode sheets (including positive and negative electrode sheets) is usually brittle and lacks toughness. For wound cells, the corners of the innermost few turns of the electrode sheets are subjected to greater pressure deformation and bending, and the active material layer is very easy to break and fall off. These foreign particles can easily increase the failure rate of the insulation withstand voltage test (Hi-pot), causing the wound cells to be scrapped and greatly affecting the yield of mass production.

[0072] In related technologies, polyimide tape (PI tape) or polypropylene blue adhesive (PP blue adhesive) is applied at the corners of the wound battery cell to prevent cracking, breakage, and powder shedding during the cold pressing process after winding. While this can alleviate the tip discharge effect of foreign particles under high voltage during Hi-pot testing, thus improving particle breakdown and Hi-pot defects, ions cannot pass through the PI tape and PP blue adhesive. This means that the area on the active material layer of the electrode sheet with the PI tape or PP blue adhesive does not participate in the charge-discharge cycle reaction, resulting in a 100% loss of active capacity in this area (approximately 0.3Ah-0.5Ah). This wastes active material and reduces the battery's cycle performance. Moreover, the high-heat-resistant and effective barrier properties of PI tape are currently expensive, further increasing the battery cost.

[0073] Figure 8 This is a cross-sectional view of a protective tape 400 according to an embodiment of the application.

[0074] Please see Figure 8 This application provides a protective tape 400, which includes an insulating substrate 410, a heat-insulating coating 420, and an adhesive layer 430. The insulating substrate 410 has pores (not shown) with nanometer-scale dimensions. The heat-insulating coating 420 is disposed on the surface of the insulating substrate 410. The adhesive layer 430 is disposed on the surface of the heat-insulating coating 420 facing away from the insulating substrate 410. The protective tape 400 has a plurality of spaced-apart channels 401, which penetrate two opposite surfaces of the protective tape 400 along the thickness direction, and the radial dimension of the channels 401 is micrometer-scale.

[0075] "Micron-scale size" refers to sizes ranging from nanometers to micrometers.

[0076] It should be noted that the insulating substrate 410 may have a heat insulation coating 420 and an adhesive layer 430 on only one surface, or it may have a heat insulation coating 420 and an adhesive layer 430 on both surfaces.

[0077] It should be noted that the thickness direction of the protective tape 400 is the same as the stacking direction of the insulating substrate 410, the heat insulation coating 420, and the adhesive layer 430.

[0078] Understandably, the insulating substrate 410, the heat-insulating coating 420, and the adhesive layer 430 are stacked sequentially. When the protective tape 400 is applied to the single cell 300, the adhesive layer 430 faces the positive electrode 311 or the negative electrode 313, and the adhesive layer 430 is used to bond the protective tape 400 to the positive electrode 311 or the negative electrode 313.

[0079] Understandably, the protective tape 400 is permeable to ions. Understandably, the protective tape 400 is ion-conducting and insulating.

[0080] Understandably, the insulating substrate 410 has nanoscale pores, and the protective tape 400 has micrometer-sized channels 401.

[0081] Optionally, the plurality of channels 401 can be arranged randomly or in an array.

[0082] Optionally, the radial dimension of the channel 401 is larger than the dimension of the pore.

[0083] The protective tape 400 of this application embodiment includes an insulating substrate 410, a heat-insulating coating 420, and an adhesive layer 430. The insulating substrate 410 has pores, which are nanoscale in size, thereby making the protective tape 400 ion-conducting, allowing metal ions (such as lithium ions and sodium ions) to pass through. When the protective tape 400 is applied to the corner of the core 310, the corner of the core 310 can still participate in charge-discharge cycles. Compared with the solution of using PI tape and PP blue glue in related technologies, it can greatly reduce the capacity loss at the adhesive application point of the core 310 of the single cell 300 and improve the capacity of the single cell 300. Because the corners of the core 310 are covered with both the separator 312 and protective tape 400, the ion transport path at the location of the protective tape 400 is lengthened (it needs to pass through both the separator 312 and the protective tape 400). This increases the interfacial impedance of the core 310, increases the resistance to ion migration, and reduces the ionic conductivity at the corners, thus reducing the cycle performance of the individual cell 300. This application addresses this by creating micron-sized pores 401 on the protective tape 400. This increases the surface roughness of the protective tape 400, allowing the electrolyte to spread and penetrate more easily. This not only reduces the air permeability of the protective tape 400 but also significantly improves its electrolyte wettability, thereby better wetting the separator 312 and protective tape 400 at the corners of the core 310. This improves the ionic conductivity at the corners of the core 310, avoids uneven internal resistance in the individual cell 300, and increases the cycle life of the individual cell 300.

[0084] Furthermore, the protective tape 400 of this application has a lower cost compared to PI tape.

[0085] Please see Figure 8 In some embodiments, the radial dimension w of the channel 401 is in the range of 0.5μm≤w≤15μm.

[0086] Specifically, the radial dimension w of the channel 401 can be, but is not limited to, 0.5μm, 1μm, 2μm, 3μm, 5μm, 6μm, 8μm, 10μm, 12μm, 14μm, 15μm, etc.

[0087] In this embodiment, if the radial dimension w of the channel 401 is too small, it will be detrimental to improving the electrolyte wettability of the protective tape 400 and will increase the processing difficulty of the channel 401. If the radial dimension w of the channel 401 is too large, it will reduce the insulation of the protective tape 400, reduce the structural strength of the protective tape 400, reduce the puncture strength of the protective tape 400, increase the probability of micro-short circuits, and will be detrimental to reducing the Hi-pot defect rate of the single cell 300.

[0088] Please see Figure 8 In some embodiments, the minimum spacing s between two adjacent channels 401 is in the range of 100μm≤s≤400μm.

[0089] Specifically, the minimum spacing s between two adjacent channels 401 can be, but is not limited to, 100μm, 120μm, 140μm, 160μm, 180μm, 200μm, 220μm, 240μm, 260μm, 280μm, 300μm, 320μm, 340μm, 360μm, 380μm, 400μm, etc.

[0090] In this embodiment, if the minimum distance s between two adjacent channels 401 is too small, the number of channels 401 on the protective tape 400 will be too large, and the walls of the two adjacent channels 401 will be too thin, reducing the structural strength and puncture resistance of the protective tape 400. If the minimum distance s between two adjacent channels 401 is too large, the improvement effect on the electrolyte wettability of the protective tape 400 will be insignificant.

[0091] In some embodiments, the distribution density of the channels 401 ranges from 500 per cm² to 10,000 per cm².

[0092] Specifically, the distribution density of the channels 401 can be, but is not limited to, 500 / cm², 1000 / cm², 2000 / cm², 3000 / cm², 4000 / cm², 5000 / cm², 6000 / cm², 7000 / cm², 8000 / cm², 9000 / cm², 10000 / cm², etc.

[0093] It should be noted that the distribution density of the channel 401 refers to the number of channels 401 per unit area.

[0094] It should be noted that, in the embodiments of this application, when the numerical range a to b is involved, unless otherwise specified, the numerical value can be any value between a and b, including the endpoint value a and the endpoint value b.

[0095] In this embodiment, if the distribution density of the channels 401 is too low, the improvement effect on the electrolyte wettability of the protective tape 400 will not be significant. If the distribution density of the channels 401 is too high, the structural strength of the protective tape 400 will be reduced, and the puncture strength of the protective tape 400 will also be reduced.

[0096] Optionally, the aperture 401 can be drilled using at least one of the following devices: femtosecond and attosecond lasers, single-die high-power semiconductor lasers, array-stacking high-power semiconductor lasers, and continuous-wave distributed feedback semiconductor lasers (CWDFB semiconductor lasers). Optionally, the light source for drilling can be, but is not limited to, at least one of the following: ultraviolet laser sources, 1550nm distributed feedback lasers (DFB lasers).

[0097] In some embodiments, the heat insulation coating 420 includes ceramic particles and toughening fibers, wherein the toughening fibers are dispersed in the ceramic particles; and the mass fraction of the toughening fibers in the heat insulation coating 420 ranges from 15 wt% to 35 wt%.

[0098] It should be noted that the ceramic particles are dispersed throughout the heat insulation coating 420, and the toughening fibers are also dispersed throughout the heat insulation coating 420.

[0099] Specifically, the mass fraction of the toughening fiber in the heat insulation coating 420 can be, but is not limited to, 15wt%, 18wt%, 20wt%, 23wt%, 25wt%, 28wt%, 30wt%, 33wt%, 35wt%, etc.

[0100] In this embodiment, the heat-insulating coating 420 includes ceramic particles and toughening fibers. The toughening fibers, spread along the surface of the insulating substrate 410, enhance the capillary effect, drive electrolyte penetration and wetting, accelerate the wetting process, and improve the wettability of the protective tape 400. Furthermore, the toughening fibers have high tensile strength and elastic modulus, and their compact molecular chain structure effectively disperses sharp external forces, delays or resists the penetration of sharp particles, and improves the puncture strength of the protective tape 400; that is, they can absorb and disperse the exothermic effect of sharp particles, alleviate the impact force of foreign particles, and improve the puncture resistance of the protective tape 400. Moreover, the toughening fibers can also form a mesh structure in the heat-insulating coating 420, further increasing the tensile and compressive strength of the heat-insulating coating 420, preventing cracks and fractures in the heat-insulating coating 420, thereby improving the wear resistance and crack resistance of the heat-insulating coating 420. Furthermore, adding toughening fibers can prevent delamination of the heat insulation coating 420, ensuring efficient transmission and dissipation of external forces within the heat insulation coating 420 and improving overall puncture resistance. Therefore, adding toughening fibers to the heat insulation coating 420 not only improves the electrolyte wettability of the protective tape 400 but also enhances its puncture resistance, increasing the yield of the single-cell battery 300 insulation withstand voltage test (Hi-pot test). If the mass fraction of the toughening fibers in the heat insulation coating 420 is too low, the content of toughening fibers is insufficient, making it impossible to form a continuous reinforcing phase and construct an effective three-dimensional reinforcing network, resulting in a smaller improvement in the puncture resistance and surface elastic modulus of the protective tape 400. If the mass fraction of the toughening fiber in the heat insulation coating 420 is too high, the toughening fiber is prone to agglomeration, the viscosity of the slurry increases dramatically during the preparation of the heat insulation coating 420, and the toughening fiber is difficult to disperse evenly, affecting the uniformity and density of the heat insulation coating 420; in addition, excessive toughening fiber may block the surface pores of the isolation substrate 410, affecting the ion conduction of the protective tape 400.

[0101] Optionally, the material of the insulating substrate 410 may include at least one of polyethylene, polypropylene, and ethylene-propylene copolymer.

[0102] In some embodiments, the average diameter of the toughening fibers ranges from 0.2 μm to 2 μm. Specifically, the average diameter of the toughening fibers can be, but is not limited to, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, etc. If the average diameter of the toughening fibers is too small, the toughening fibers are prone to agglomeration during the preparation of the heat insulation coating 420 slurry, making it difficult to disperse evenly in the slurry. The ultrafine toughening fibers can easily block the pore channels between ceramic particles, affecting electrolyte penetration and ion transport. If the average diameter of the toughening fibers is too large, the density of the heat insulation coating 420 decreases, the puncture resistance weakens, and the thermal shrinkage rate increases.

[0103] In some embodiments, the average aspect ratio of the toughening fibers ranges from 20 to 200. Specifically, the average aspect ratio of the toughening fibers can be, but is not limited to, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, etc. If the average aspect ratio of the toughening fibers is too small, the toughening fibers are too short, making it difficult to form an effective bridging network, unable to effectively transfer loads, resulting in low stress transfer efficiency, limited improvement in the puncture strength of the protective tape 400, and limited improvement in the Hi-pot defect rate of the single cell 300; in addition, the short toughening fibers have a small contact area with the insulating substrate 410, resulting in low interfacial bonding strength. If the average aspect ratio of the toughening fibers is too large, the toughening fibers are too long, and long heat-increasing fibers are prone to entanglement and agglomeration, affecting the uniformity of the slurry of the heat insulation coating 420, and long fibers in the heat insulation coating 420 are prone to uneven orientation and accumulation, resulting in stress concentration and failure of the improvement effect.

[0104] In some embodiments, the toughening fiber includes at least one selected from aramid fiber, polyimide fiber, and polyacrylonitrile fiber. These fibers have high toughness and elastic modulus, which can better improve the electrolyte wettability of the protective tape 400, improve the puncture resistance of the protective tape 400, and reduce the high-pot defect rate of the single cell 300.

[0105] Optionally, the ceramic particles include at least one of alumina, boehmite, silicon nitride, and silicon carbide.

[0106] In some embodiments, the median particle size Dv50 of the ceramic particles ranges from 0.3 μm ≤ Dv50 ≤ 1.0 μm. Specifically, the median particle size Dv50 of the ceramic particles can be, but is not limited to, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, etc. In this embodiment, if the median particle size Dv50 of the ceramic particles is too small, the heat insulation coating 420 will be too dense, and the pores inside the heat insulation coating 420 will be too small, hindering the wetting and penetration of the electrolyte and reducing the electrolyte wettability of the protective tape 400. In addition, if the median particle size Dv50 of the ceramic particles is too small, the ceramic particles are prone to agglomeration and are difficult to disperse evenly, making it difficult to ensure the uniformity of the coating. If the median particle size Dv50 of the ceramic particles is too large, the heat insulation coating 420 will be too sparse and the internal pores will be too large. Although this is conducive to the wetting of the electrolyte, the ability to resist the puncture of foreign particles will be greatly reduced, and the heat resistance of the protective tape 400 will also be significantly reduced.

[0107] Optionally, the median particle size Dv50 of the ceramic particles can be obtained by testing with a laser particle size analyzer.

[0108] Optionally, the toughening fiber has hydroxyl or carboxyl groups. Understandably, the toughening fiber can be a modified toughening fiber with hydroxyl or carboxyl groups. By grafting hydroxyl or carboxyl groups onto the toughening fiber, the bonding force between the toughening fiber and the ceramic powder can be better improved, which is beneficial to the uniform dispersion of the toughening fiber in the ceramic powder and further improves the puncture resistance of the protective tape 400.

[0109] Figure 9 A cross-sectional view of a protective tape 400 according to another embodiment of the application.

[0110] Please see Figure 9 In some embodiments, the adhesive layer 430 includes a plurality of adhesive points 431 spaced apart on the surface of the heat insulation coating 420 facing away from the insulating substrate 410, and the glass transition temperature of the adhesive layer 430 is less than or equal to 30°C.

[0111] It should be noted that multiple adhesive points 431 can be arranged in an array, even if they are arranged randomly.

[0112] It should be noted that when the channel 401 is located at the bonding point 431, the channel 401 penetrates the insulating substrate 410, the heat insulation coating 420 and the adhesive layer 430 respectively. When the channel 401 is staggered from the bonding point 431, the channel 401 penetrates the insulating substrate 410 and the heat insulation coating 420 respectively.

[0113] Specifically, the glass transition temperature of the adhesive layer 430 can be, but is not limited to, less than or equal to 30°C, less than or equal to 28°C, less than or equal to 25°C, less than or equal to 23°C, less than or equal to 20°C, less than or equal to 18°C, less than or equal to 15°C, less than or equal to 13°C, less than or equal to 10°C, less than or equal to 5°C, less than or equal to 0°C, less than or equal to -10°C, less than or equal to -20°C, less than or equal to -30°C, etc.

[0114] Optionally, the adhesive layer 430 may include, but is not limited to, at least one of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polymethyl methacrylate (PMMA), polyacrylate, etc.

[0115] Polyvinylidene fluoride-hexafluoropropylene can be a graft copolymer of polyvinylidene fluoride and hexafluoropropylene, that is, a graft copolymer with polyvinylidene fluoride as the main chain and polyhexafluoropropylene as the branch chain.

[0116] It should be noted that when the core 310 is being wound, an auxiliary baking lamp can be added to the adhesive application points of the positive electrode 311 and negative electrode 313 of the winding equipment, which can further shorten the bonding time required for the protective tape 400 (pressing and pasting time: 1s to 3s).

[0117] In this embodiment, the winding time of the core 310 is very short, that is, the pressure stay time is very short during winding. This requires the adhesive layer 430 to have high adhesion (i.e., high adhesion pressure-sensitive adhesive at room temperature) so that it can be quickly pressed to produce an adhesive effect. This allows the protective tape 400 to be bonded to the surface of the positive electrode 311 or the negative electrode 313, thereby fixing the positive active material layer of the positive electrode 311 or the negative active material layer of the negative electrode 313 and fixing the powder falling off the positive and negative active material layers.

[0118] In some embodiments, the electrolyte wetting distance on the side of the protective tape 400 having the adhesive layer 430 is greater than or equal to 50 mm. The electrolyte wetting distance refers to the distance the electrolyte spreads along the length of the protective tape 400 after 1 minute when 0.5 mL of electrolyte is dropped onto the side of the protective tape 400 having the adhesive layer 430 with a size of 5 mm × 200 mm.

[0119] It should be noted that the greater the electrolyte wetting distance, the better the electrolyte wetting properties of the protective tape 400.

[0120] Specifically, the electrolyte wetting distance on the side of the protective tape 400 having the adhesive layer 430 can be, but is not limited to, 50mm, 53mm, 55mm, 58mm, 60mm, 63mm, 65mm, 68mm, 70mm, etc.

[0121] The protective tape 400 of this application has a high electrolyte wetting distance on one side of the adhesive layer 430, thereby having a high ionic conductivity. When applied to the corner of the core 310 of the single cell 300, it will not cause capacity loss at the corner, thus giving the single cell 300 a high cycle life.

[0122] Optionally, the thickness of the protective tape 400 ranges from 10 μm to 30 μm. Specifically, the thickness of the protective tape 400 can be, but is not limited to, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, etc.

[0123] In some embodiments, the puncture strength of the protective tape 400 is greater than or equal to 400 gf. Specifically, the puncture strength of the protective tape 400 can be, but is not limited to, 400 gf, 420 gf, 440 gf, 460 gf, 480 gf, 500 gf, 520 gf, 540 gf, 560 gf, 580 gf, 600 gf, 620 gf, 640 gf, 660 gf, 680 gf, etc. The protective tape 400 of this application has high puncture strength and, when applied to the corner of the core 310 of the single cell 300, can effectively alleviate the tip discharge effect of foreign particles under high voltage during Hi-pot testing, improve foreign particle breakdown or Hi-pot defects, and reduce the Hi-pot defect rate of the single cell 300.

[0124] In some embodiments, the surface elastic modulus E of the adhesive layer 430 side of the protective tape 400 is in the range of 600 MPa ≤ E ≤ 2000 MPa. Specifically, the surface elastic modulus E of the adhesive layer 430 side of the protective tape 400 can be, but is not limited to, 600 MPa, 800 MPa, 1000 MPa, 1200 MPa, 1400 MPa, 1600 MPa, 1800 MPa, 2000 MPa, etc. If the surface elastic modulus E of the adhesive layer 430 side of the protective tape 400 is too small, the protective tape 400's ability to resist external particulate matter will decrease, and the microporous structure will be easily deformed by compression, affecting ion transport. If the surface elastic modulus E of the adhesive layer 430 side of the protective tape 400 is too large, the rigidity of the protective tape 400 will be too large. During the cycle of the single cell 300, it will be difficult to adapt to the volume changes of the positive electrode 311 and the negative electrode 313, which will easily lead to local stress concentration of the protective tape 400 and accelerate microstructure damage.

[0125] Furthermore, the surface elastic modulus E of the adhesive layer 430 side of the protective tape 400 is in the range of 1000MPa≤E≤2000MPa.

[0126] In some embodiments, the air permeability of the protective tape 400 is between 10s / 100cc and 50s / 100cc. Specifically, the air permeability of the protective tape 400 can be, but is not limited to, 10s / 100cc, 20s / 100cc, 30s / 100cc, 40s / 100cc, 50s / 100cc, etc. The corner of the core 310 includes a diaphragm 312 and the protective tape 400. The electrolyte needs to quickly and fully wet the protective tape 400 so that ions can penetrate the internal pore structure of the protective tape 400 and the diaphragm 312. If the air permeability of the protective tape 400 is too high, the electrolyte wettability at the corner of the core 310 will be insufficient, resulting in low ionic conductivity in this area. This may lead to an increase in the internal resistance of the single cell 300 and aggravated cycle performance degradation. If the air permeability of the protective tape 400 is too low, i.e., the diameter of the pores 401 is too large or the spacing of the pores 401 is too small, it may lead to a weakening of the strength of the protective tape 400 itself, reducing the puncture resistance. The heat resistance of the protective tape 400 will also be affected, and it may even aggravate the self-discharge phenomenon, resulting in a deterioration in the storage performance of the single cell 300.

[0127] In some embodiments, after the protective tape 400 is bonded to the positive electrode 311, the average peel strength Q between the protective tape 400 and the positive electrode 311 ranges from 5 N / m to Q to 15 N / m. Specifically, after the protective tape 400 is bonded to the positive electrode 311, the average peel strength Q between the protective tape 400 and the positive electrode 311 can be, but is not limited to, 5 N / m, 8 N / m, 10 N / m, 13 N / m, 15 N / m, etc. If the average peel strength Q between the protective tape 400 and the positive electrode 311 is too high, that is, the bonding strength between the protective tape 400 and the positive electrode 311 is too high, it will increase the obstruction of ions penetrating the protective tape 400 from the positive electrode, affecting ion transport. If the average peel strength Q between the protective tape 400 and the positive electrode 311 is too low, that is, the bonding strength between the protective tape 400 and the positive electrode 311 is too low, once foreign particles fall off at the corner of the core 310, the protective tape 400 will not be able to firmly adhere to the foreign particles, resulting in a very high risk of Hi-pot defects.

[0128] The following specific embodiments further describe the single cell 300 and the protective tape 400 of this application.

[0129] Examples 1 to 22, Comparative Example 1 The protective tape 400 in this embodiment is prepared through the following steps: (1) Preparation of the slurry for the heat insulation coating 420: Alumina powder (ceramic particles), styrene-butadiene rubber (SBR), acrylic resin emulsion, and polyvinyl alcohol (surfactant) were weighed in a mass ratio of 94.5:3:2:0.5. First, deionized water was added to the stirrer as a solvent, then the weighed polyvinyl alcohol was added, and the mixture was stirred evenly at 1000 rpm / 15 min. Then, alumina powder (Dv50 of 400 nm) was added, and the mixture was stirred evenly at 2000 rpm / 60 min. Then, SBR was added, and the mixture was stirred evenly at 500 rpm / 15 min. Then, acrylic resin emulsion was added, and the mixture was stirred evenly at 500 rpm / 15 min. Finally, the mixture was slowly stirred at 500 rpm / 15 min to eliminate air bubbles, and the slurry for the heat insulation coating 420 was obtained. The mass fraction and parameters of the toughening fibers in the heat insulation coating 420 of each embodiment and comparative example are shown in Table 1 below.

[0130] After adding aramid fibers, the mass of alumina powder decreases accordingly, while the mass of other components remains unchanged. First, deionized water is added to a stirrer as a solvent, followed by the weighed polyvinyl alcohol. The mixture is stirred at 1000 rpm for 15 minutes until homogeneous. Then, alumina powder (Dv50 = 400 nm) is added and stirred at 2000 rpm for 60 minutes until homogeneous. Next, aramid fibers are added and stirred at 2000 rpm for 30 minutes until homogeneous. Then, SBR is added and stirred at 500 rpm for 15 minutes until homogeneous. Finally, acrylic resin emulsion is added and stirred at 500 rpm for 15 minutes until homogeneous. Finally, the mixture is slowly stirred at 500 rpm for 15 minutes to eliminate air bubbles, resulting in the slurry for the heat insulation coating 420. It is important to note that aramid fibers are prone to agglomeration and are not easily dispersed uniformly in water. Therefore, the aramid fibers can be pre-dispersed uniformly in an aqueous solution of polyvinyl alcohol using high-speed stirring, and ultrasonic dispersion can be used to assist in the dispersion process.

[0131] (2) Preparation of adhesive layer 430 slurry: Weigh PVDF-HFP powder, polyacrylic acid (PAA), acrylic resin emulsion and water-soluble additive glycerol according to the preset mass ratio of 56:15:28:1; first add deionized water as solvent in the stirrer, then add the weighed PAA, stir evenly at 1000rpm / 15min, then add glycerol, stir evenly at 1000rpm / 15min, control the temperature at about 40℃, control the pH at about 7; then add PVDF-HFP powder, stir evenly at 2500rpm / 90min, then add acrylic resin emulsion, stir evenly at 1000rpm / 15min, then slowly stir at 500rpm / 15min to eliminate bubbles, and obtain adhesive layer 430 slurry.

[0132] (3) Preparation of protective tape 400: First, a layer of heat insulation coating 420 slurry is gravure-coated onto a 9μm thick PE insulating substrate 410, controlling the coating thickness to be 2μm to 3μm. After drying, the single-sided surface density of the heat insulation coating 420 is 4.0 g / m². 2 Then, apply a single-sided adhesive layer of 430 slurry by roller coating, controlling the single-sided surface density to be 0.8 g / m². 2 After drying, laser drilling is performed to form multiple channels 401 (circular channels 401) on the protective tape 400. Finally, it is slit and wound into a protective tape 400 with a width of 15mm. The thickness of the protective tape 400 is 18μm. The porous parameters of the protective tape 400 in each embodiment and comparative example are shown in Table 1 below.

[0133] (4) Preparation of sodium-ion battery (single cell 300): The positive electrode 311, separator 312 and negative electrode 313 of sodium-ion battery are arranged in order, so that the separator 312 is placed between the positive electrode 311 and the negative electrode 313 to play a role in isolation. Through precise calculation of the bending corner position of the inner ring of the bare cell, the corner of the inner ring positive electrode 311 is specially glued (protective tape 400 is applied, wherein the adhesive layer 430 faces the positive electrode 311). The initial glue application position is the bending point of the first fold of the innermost positive electrode 311 of the bare cell. Protective tape 400 is applied to both the front and back of the positive electrode 311 at the bending point. The number of glue application positions is calculated from the first fold of the innermost positive electrode 311. The number of glue application positions is 4 (i.e., four rings). Then, the next step is to wind the bare cell. The bare battery cell was pressed at room temperature to obtain core 310, with the unit area pressure controlled at 4.8 MPa and the holding time at 40 s. Finally, core 310 was placed in an aluminum alloy square shell, vacuum dried, and then injected with electrolyte. After vacuum sealing, settling, and formation processes, a sodium-ion battery was obtained.

[0134] Comparative Example 2 The difference between this comparative example and the various embodiments is that the lithium-ion battery in this comparative example only has a separator 312 between the positive electrode 311 and the negative electrode 313, and no protective tape 400 is provided.

[0135] The following performance tests were performed on the protective tape 400 and sodium-ion batteries of each embodiment and comparative example: (1) Aspect ratio of toughened fiber: The projection length method is used to test the aspect ratio of the major axis length in the projection of the fiber material to its average diameter. The BT-2900 dynamic image particle size and shape analysis system (model: Dandong Baite BT-2900) is used to test the aspect ratio of the fiber in the two-dimensional plane (applicable to curved fibers that cannot be completely straightened). The aspect ratio is the ratio of the projection length to the diameter. The average aspect ratio is obtained by taking the average value of 3 tests.

[0136] (2) Thickness of protective tape 400: Refer to the thickness test method in 6.4.1 of the standard GB / T 36363-2018 Polyolefin separator for lithium-ion batteries. Use a thickness gauge (model: German Maer C1202) to test the thickness of the single-layer separator 312. Use a flat probe with a probe diameter of φ = 8 mm and a test pressure of 0.25 N. Take the average value after 5 tests.

[0137] (3) Air permeability of protective tape 400: Referring to the air permeability test method in 6.5.4 of the standard GB / T 36363-2018 Polyolefin separator for lithium-ion batteries, an air permeability tester (model: Wangyan EG01-55-1MR) was used to test the time required for 100 mL of air to pass through 1 square inch of separator 312 under a pressure of 1.22 kPa. This is the air permeability value. Five tests were performed and the average value was taken. The smaller the air permeability value, the better the air permeability of separator 312.

[0138] (4) The surface density of the adhesive layer 430 of the protective tape 400: The test was conducted according to the standard GB / T 20220-2006 "Determination of Average Thickness, Average Thickness of Roll and Area per Unit Mass of Plastic Films and Sheets - Weighing Method", using a 100cm... 2 Five pieces of the isolation substrate 410 and five pieces of the isolation substrate 410 with the adhesive layer 430 were cut using a grammage sampler. The weights of the samples were measured and then divided by the sampling area to obtain the areal density of each sample. The difference between the two is the areal density of the adhesive layer 430. The average value was taken after five tests.

[0139] (5) Puncture strength of protective tape 400: Following the puncture strength test method in 6.5.3 of standard GB / T 36363-2018 "Polyolefin Separator for Lithium-ion Batteries", a universal testing machine was used for testing. The sample was clamped in a fixture, and a 1mm diameter semi-circular needle was used at a speed of 100mm / min to penetrate the protective tape 400 sample. The heat insulation coating 420 of the heat insulation coating slurry faced the needle. Five tests were performed, and the average value was taken. The higher the puncture strength value, the better the puncture resistance of the protective tape 400.

[0140] (6) Elastic modulus of protective tape 400: Referring to the standard "ASTM E2546-15 Standard Practice for Instrumented Indentation Testing", the surface elastic modulus of protective tape 400 was tested using a nanoindenter (model: Anton Paar NHT³ nanoindenter). The sample size was cut to 20mm×20mm and pasted on a glass slide. The test surface was the heat insulation coating 420 surface of the protective tape 400 facing the positive electrode 311. Dotted nanoindentation test points were set in the central area of ​​the sample, with a spacing of 0.5mm between adjacent indentation test points. A triangular pyramidal diamond indenter was used. The load was set to the loading-unloading mode, with a peak value of 10mN and a loading speed of 1.0Mn / s. Loading was stopped after unloading to 90% of the peak value, and the holding time was 5s. The surface elastic modulus of protective tape 400 was calculated, and the average value was taken after 5 tests.

[0141] (7) Average peel strength between protective tape 400 and positive electrode 311: The peel strength of protective tape 400 and positive electrode 311 was tested according to the standard GB / T 2792-2014 Test Method for Peel Strength of Adhesive Tape. After pressing, the sample size was cut to 20mm×100mm and fixed in the middle of the clamp of the tensile testing machine. Then, the tensile testing machine peeled the protective tape 400 and positive electrode 311 along the 180° direction at a speed of 50mm / min. The test distance was 80mm. Five samples were tested and the average value was taken. The adhesive force was the average peel strength. The pressing method of protective tape 400 and positive electrode 311 was as follows: cut 100mm×100mm positive electrode 311 and protective tape 400, stack them naturally and put them into a flat plate press for pressing. The room temperature pressing temperature was 25℃, the holding time was 3s, and the unit area pressure was 2.0MPa.

[0142] (8) Electrolyte wetting distance on the side of the protective tape 400 with the adhesive layer 430: Electrolyte wetting distance test was performed on the protective tape 400. The protective tape 400 was cut into a sample with a size of 5mm×200mm. 0.5mL of electrolyte was dropped on the side of the protective tape 400 with the adhesive layer 430. The diffusion distance of the electrolyte in the 200mm length direction was observed within 1 minute. The test was performed 5 times and the average value was taken.

[0143] (9) Hi-pot defect rate of core 310: Control the ambient humidity ≤30%RH, ensure no indentation, no damage, and no wrinkling of the diaphragm 312 during hot pressing of bare cells. Bare cell pressing process: temperature 25±5℃, pressing pressure 4MPa, pressing time 40s. Perform insulation withstand voltage test on bare cells. Hi-pot test voltage is 100±1V, test time is 5±1s, test mode is "PASS" mode, and the lower limit of resistance is 5MΩ. Test 300 bare cells and calculate the hot pressing Hi-pot defect rate.

[0144] (10) Energy efficiency of a single cell (25℃): Under 25℃ conditions, the sodium-ion battery was charged and discharged using 1P charging and 1P discharging cycles, with a charging cutoff voltage of 3.3V and a discharging cutoff voltage of 1.5V, until the sodium-ion battery capacity reached 60% of the initial capacity. At the same time, the energy efficiency of the sodium-ion battery after 2 cycles was tested using the constant power method. Energy efficiency = discharge energy of the second cycle / charging energy of the second cycle × 100%.

[0145] (11) The charging capacity and discharging capacity of a single cell 300: Under the condition of 25℃, the sodium-ion battery is charged and discharged by 1P charging and 1P discharging, wherein the charging cut-off voltage is 3.3V and the discharging cut-off voltage is 1.5V, and the cycle is repeated for 3 cycles. The charging capacity value of the second cycle is taken as the charging capacity, and the discharging capacity value of the second cycle is taken as the discharging capacity.

[0146] The performance parameters of the protective tape 400 and the single cell 300 in each embodiment and comparative example are shown in Table 1 and Table 2 below.

[0147] Table 1. Composition and some performance parameters of the protective tape 400 in each embodiment and comparative example.

[0148] Table 2. Partial performance parameters of the protective tape 400 and the single cell 300 in each embodiment and comparative example.

[0149] The test results from Examples 1 to 6, Comparative Example 1, and Comparative Example 2 show that the single cell 300 of Comparative Example 2, lacking the protective tape 400, exhibits high charging capacity, discharging capacity, and energy efficiency. However, the core 310 of Comparative Example 2 suffers from a high hot-pressing Hi-pot defect rate. The single cell 300 of Comparative Example 1 is equipped with the protective tape 400; however, the tape 400 lacks channels 401, significantly reducing the hot-pressing Hi-pot defect rate and also lowering the charging and discharging capacity of the single cell 300. Furthermore, the protective tape 400 of Comparative Example 1 has higher permeability, a lower electrolyte wetting distance, and a lower average peel strength between the protective tape 400 and the positive electrode 311. In Examples 1 to 6, the protective tape 400 is provided with multiple channels 401 spaced apart. The air permeability of the protective tape 400 is greatly reduced, and the puncture strength and surface elastic modulus are slightly reduced. The average peel strength between the protective tape 400 and the positive electrode 311 and the electrolyte wetting distance of the protective tape 400 are greatly increased. The hot-pressing Hi-pot defect rate of the core 310 is also reduced when the radial dimension (i.e., aperture) of the channel 401 is controlled within a certain range. The charging capacity and discharging capacity of the single cell 300 are also improved. When the minimum spacing s between two adjacent channels 401 remains unchanged, as the radial dimension of the channels 401 of the protective tape 400 increases, the distribution density of the channels 401 gradually decreases, the effective bonding area between the protective tape 400 and the positive electrode 311 becomes smaller, the air permeability of the protective tape 400 gradually decreases, the puncture strength gradually decreases, and the surface elastic modulus also gradually decreases. In addition, the average peel strength between the protective tape 400 and the positive electrode 311 gradually decreases, the electrolyte wetting distance of the protective tape 400 gradually increases, the Hi-pot defect rate of the core 310 gradually increases, the charging capacity and discharging capacity of the single cell 300 slightly increase, and the energy efficiency of the single cell 300 also gradually increases.

[0150] The test results from Examples 3, 7 to 11 show that when the radial dimension of the channel 401 remains constant, as the spacing between adjacent channels 401 increases, the distribution density of the channels 401 gradually decreases, the effective bonding area between the protective tape 400 and the positive electrode 311 decreases, the air permeability of the protective tape 400 gradually increases, the puncture strength gradually increases, and the surface elastic modulus gradually increases. The average peel strength between the protective tape 400 and the positive electrode 311 gradually increases, the electrolyte wetting distance of the protective tape 400 first gradually increases and then gradually decreases; the Hi-pot defect rate of the core 310 gradually decreases, the charging capacity and discharging capacity of the single cell 300 slightly decrease, and the energy efficiency of the single cell 300 slightly decreases.

[0151] The test results from Examples 12 to 18 show that adding toughening fibers to the heat insulation coating 420 can reduce the air permeability of the protective tape 400 and significantly improve the puncture strength and surface elastic modulus of the protective tape 400. In addition, it can also improve the average peel strength between the protective tape 400 and the positive electrode 311, increase the electrolyte wetting distance of the protective tape 400, reduce the Hi-pot defect rate of the core 310, and improve the charging capacity, discharging capacity, and energy efficiency of the single cell 300.

[0152] Furthermore, the test results from Examples 12 to 18 show that as the mass fraction of toughening fibers in the heat insulation coating 420 increases, the air permeability of the protective tape 400 gradually decreases, indicating that the air permeability of the protective tape 400 gradually improves. As the mass fraction of toughening fibers in the heat insulation coating 420 increases, the puncture strength and surface elastic modulus of the protective tape 400 first gradually increase and then gradually decrease; as the mass fraction of toughening fibers in the heat insulation coating 420 increases, the average peel strength between the protective tape 400 and the positive electrode 311 gradually increases; the electrolyte wetting distance of the protective tape 400 first gradually increases and then gradually decreases; the Hi-pot defect of the core 310 first gradually decreases and then gradually increases; the charging capacity and discharging capacity of the single cell 300 first gradually increase and then gradually decrease; and the energy efficiency of the single cell 300 also first increases and then decreases. In Example 12, the toughening fiber mass fraction of the heat insulation coating 420 is low, resulting in fewer toughening fibers and difficulty in forming a continuous reinforcing phase and constructing an effective three-dimensional reinforcing network. Consequently, the improvement in the puncture resistance and surface elastic modulus of the protective tape 400 is minimal. In Example 18, the toughening fiber mass fraction is high, making the toughening fibers prone to agglomeration. This leads to a sharp increase in the viscosity of the heat insulation coating 420 solution and makes uniform dispersion difficult, affecting the uniformity and density of the heat insulation coating 420. Furthermore, excessive toughening fibers may even clog the pores on the surface of the insulating substrate 410, affecting ion conduction. Therefore, the puncture strength, surface elastic modulus, and other properties of the protective tape 400 in Example 18 actually decrease, while the Hi-pot defect rate of the core 310 increases.

[0153] The test results from Examples 14, 19 to 23 show that as the aspect ratio of the toughening fibers in the heat insulation coating 420 increases, the air permeability of the protective tape 400 gradually increases. As the aspect ratio of the toughening fibers in the heat insulation coating 420 increases, the puncture strength and surface elastic modulus of the protective tape 400 first gradually increase and then gradually decrease. As the aspect ratio of the toughening fibers in the heat insulation coating 420 increases, the average peel strength between the protective tape 400 and the positive electrode 311 gradually increases. The electrolyte wetting distance of the protective tape 400 first gradually increases and then gradually decreases. The Hi-pot defect of the core 310 first gradually decreases and then gradually increases. The charging capacity and discharging capacity of the single cell 300 first gradually increase and then gradually decrease. The energy efficiency of the single cell 300 also first increases and then decreases. In Example 19, the toughening fibers of the heat insulation coating 420 have a small aspect ratio. The short fibers are difficult to form an effective bridging network, which cannot effectively transfer the load and results in low stress transfer efficiency, thus limiting the improvement effect on the protective tape 400. In Example 23, the toughening fibers have a large aspect ratio. The long fibers are prone to entanglement and agglomeration, affecting the uniformity of the heat insulation coating 420 solution. Furthermore, the long fibers in the heat insulation coating 420 are prone to uneven orientation and accumulation, leading to stress concentration and failure of the improvement effect.

[0154] 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.

[0155] 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 protective tape, characterized in that, The protective tape includes: An isolation substrate having multiple pores of nanoscale size; A heat-insulating coating, wherein the heat-insulating coating is disposed on the surface of the insulating substrate; and An adhesive layer is disposed on the surface of the heat-insulating coating opposite to the insulating substrate; The protective tape has a plurality of channels spaced apart, each channel penetrating two opposite surfaces of the protective tape along its thickness direction, and the radial dimension of the channels is on the order of micrometers.

2. The protective tape according to claim 1, characterized in that, The radial dimension w of the channel is in the range of 0.5μm≤w≤15μm.

3. The protective tape according to claim 1, characterized in that, The minimum spacing s between two adjacent channels is in the range of 100μm≤s≤400μm.

4. The protective tape according to claim 1, characterized in that, The distribution density of the channels ranges from 500 channels / cm² to 10,000 channels / cm².

5. The protective tape according to claim 1, characterized in that, The heat-insulating coating comprises ceramic particles and toughening fibers, wherein the toughening fibers are dispersed in the ceramic particles; the mass fraction of the toughening fibers in the heat-insulating coating ranges from 15 wt% to 35 wt%.

6. The protective tape according to claim 1, characterized in that, The heat-insulating coating satisfies at least one of the following conditions: The average diameter of the toughening fibers ranges from 0.2 μm to 2 μm; The average aspect ratio of the toughening fiber ranges from 20 to 200; The toughening fiber includes at least one of aramid fiber, polyimide fiber, and polyacrylonitrile fiber; and The median particle size Dv50 of the ceramic particles ranges from 0.3 μm to 1.0 μm.

7. The protective tape according to any one of claims 1-6, characterized in that, The electrolyte wetting distance on the side of the protective tape with the adhesive layer is greater than or equal to 50 mm. The electrolyte wetting distance refers to the distance the electrolyte spreads along the length of the protective tape after 1 minute when 0.5 mL of electrolyte is dropped onto the side of the protective tape with the adhesive layer and a size of 5 mm × 200 mm.

8. The protective tape according to claim 1, characterized in that, The protective tape meets at least one of the following conditions: The puncture strength of the protective tape is greater than or equal to 400 gf; The surface elastic modulus E of the adhesive layer side of the protective tape is in the range of 600MPa≤E≤2000MPa; and The air permeability of the protective tape ranges from 10s / 100cc to 50s / 100cc.

9. A single-cell battery, characterized in that, The single-cell battery includes a core, which includes a positive electrode, a separator, a negative electrode, a protective tape as described in any one of claims 1-8, and an electrolyte. The separator is disposed between the positive electrode and the negative electrode. The positive electrode, the separator, and the negative electrode are stacked and wound to make the core have a wound structure. The protective tape is disposed on the surface of at least one of the positive electrode and the negative electrode facing the separator and is located at the corner of the core. The adhesive surface of the protective tape faces the positive electrode or the negative electrode.

10. An energy storage device, characterized in that, The energy storage device includes one or more single-cell batteries as described in claim 9.

11. An electrical system, characterized in that, The power system includes: Electrical equipment; and The energy storage device of claim 10, wherein the energy storage device is used to supply power to the electrical equipment.

Images