Lithium-embedded adhesive tape and battery

Abstract

The utility model relates to a lithium-embedded adhesive tape and a battery, and belongs to the technical field of lithium battery adhesive tapes. The utility model provides a lithium-embedded adhesive tape which is used for being attached to a negative plate and being rolled into a battery cell along with the negative plate, and the lithium-embedded adhesive tape comprises a porous base material layer, the active coating is formed on the surface, in the thickness direction, of the porous base material layer, and the active coating is of a porous structure and can make contact with the surface of the negative plate; wherein the thickness ratio of the active coating to the porous base material layer is (1-20): 1. Through the structural design of the lithium-embedded adhesive tape, the lithium ion transmission efficiency is improved while the lithium precipitation phenomenon in the charging and discharging process of the lithium battery is effectively relieved, and the production efficiency of the lithium battery is remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium battery tapes, and in particular to a lithium-embedded tape and a battery. Background Art

[0002] Lithium battery is an important type of battery. Its battery cell is usually made by stacking and winding layers such as positive electrode sheets, separators and negative electrode sheets, and then undergoing processes such as hot pressing, liquid injection and chemical composition.

[0003] During the winding process of the electrode, the bending radius of the curved part formed by the winding increases continuously with the increase in the number of winding turns. The outer bending area of ​​the curved part along the thickness direction of the electrode is much larger than the inner bending area. The lithium ion transmission is not equivalent. The thickness expansion ratio of the positive and negative electrode sheets is inconsistent during the charging and discharging process of the battery. The electrode is prone to deformation and wrinkles, which leads to lithium deposition and damage to the battery cell structure.

[0004] To this end, the existing technology applies a coating with a certain thickness on the surface of the pole piece. The coating can provide a pre-expansion space for the pole pieces to squeeze each other and release stress when they expand, thereby improving the lithium precipitation phenomenon caused by the wrinkles of the pole pieces. However, the coating process on the pole piece requires complex coating, drying and curing process steps, which greatly inhibits the production efficiency of lithium batteries, and the coating has poor air permeability, resulting in severe limitation of lithium ion transmission efficiency during the charging and discharging process of lithium batteries. Utility Model Content

[0005] The present application provides a lithium-embedded tape and a battery to solve the technical problems in the prior art of low battery production efficiency, severe limitation of battery lithium ion transmission efficiency, and inequality in lithium ion transmission.

[0006] According to one aspect of the present application, a lithium-embedded tape is provided, which is used to be bonded to a negative electrode sheet and rolled up with the negative electrode sheet to form a battery cell. The lithium-embedded tape includes: a porous substrate layer; an active coating formed on the surface of the porous substrate layer along the thickness direction, the active coating presents a porous structure and is configured to be able to contact the surface of the negative electrode sheet; wherein the thickness ratio of the active coating to the porous substrate layer is (1 to 20):1.

[0007] In some embodiments, the lithium-embedded tape further includes: a conductive adhesive layer formed on the side of the active coating layer away from the porous substrate layer along the thickness direction, and the conductive adhesive layer is used to bond with the surface of the negative electrode sheet; wherein the thickness of the conductive adhesive layer is less than the thickness of the porous substrate layer, and the conductive adhesive layer non-continuously covers the surface of the active coating layer.

[0008] In some embodiments, the conductive adhesive layer is provided with a plurality of through-going air-permeable cavities along the thickness direction, so that the active coating is at least partially exposed toward the conductive adhesive layer.

[0009] In some embodiments, the plurality of air-permeable cavities are arranged in an array, and the plurality of air-permeable cavities are in a groove shape and / or a hole shape.

[0010] In some embodiments, the coverage area of ​​the conductive adhesive layer on the active coating accounts for 10-50% of the total area of ​​the active coating facing the conductive adhesive layer.

[0011] In some embodiments, the porosity of the active coating is set to 25-80%; and / or the porosity of the porous substrate layer is set to 30-85%, and the pore size is set to ≤10 μm.

[0012] In some embodiments, the lithium-intercalated tape further comprises a release layer; the release layer can be coated on the side of the porous substrate layer away from the active coating along the thickness direction, or can be peeled off and disposed on the side of the conductive adhesive layer away from the active coating along the thickness direction.

[0013] In some embodiments, the overall thickness of the lithium-intercalated tape is 20-150 μm; wherein the porous substrate layer is 5-50 μm thick; and / or the active coating layer is 5-100 μm thick; and / or the conductive adhesive layer is less than 10 μm thick; and / or the release layer is less than 1 μm thick.

[0014] Another aspect of the present application provides a battery, comprising the lithium-intercalated tape as described above.

[0015] In some embodiments, the battery further includes a positive electrode sheet, a separator and a negative electrode sheet; the lithium-embedded tape is bonded to at least one side of the negative electrode sheet along the thickness direction, and the positive electrode sheet, the separator and the negative electrode sheet bonded with the lithium-embedded tape are stacked in sequence and rolled to form a battery cell.

[0016] Compared with the prior art, the lithium-embedded tape and battery provided in this application have at least the following beneficial effects:

[0017] The lithium-inserting tape provided by the present application is used to be attached to the negative electrode sheet and wound with the negative electrode sheet into a battery core. It mainly includes a porous substrate layer and an active coating layer. The active coating layer is formed on the surface of the porous substrate layer along the thickness direction. The active coating layer can contact the surface of the negative electrode sheet, so as to be wound with battery components such as the negative electrode sheet, the positive electrode sheet and the separator to form a battery core. The thickness ratio of the active coating layer to the porous substrate layer is (1-20):1. The active coating layer has a higher thickness proportion in the lithium-inserting tape, which is beneficial to serving as a lithium storage warehouse during the lithium ion transmission process and providing stress buffering for the expansion of the electrode sheet, so that the excess lithium ions that should have been accumulated and precipitated can be stored and transitioned in the active coating layer during the charge and discharge process, avoiding the lithium precipitation phenomenon caused by electrode sheet wrinkles and non-equivalent lithium ion transmission; moreover, both the porous substrate layer and the active coating layer have a porous structure, which can make the lithium-inserting tape have higher volume change adaptability, which is beneficial to the stress release of the electrode sheet, and at the same time is also beneficial to effectively improving the air permeability of the lithium-inserting tape in the battery core, thereby improving the lithium ion transmission efficiency; in addition, by designing the active coating layer on the porous substrate layer to form the lithium-inserting tape, during the battery production process, the lithium-inserting tape containing the active coating layer can be directly used to attach to the electrode sheet for core winding, without the need to perform complex treatments such as active coating, drying and curing on the electrode sheet during the battery production process, which is beneficial to simplifying the lithium battery production process, thereby effectively improving the lithium battery production efficiency.

[0018] Thus, through the structural design of the lithium-inserting tape, the present application effectively alleviates the lithium precipitation phenomenon during the charge and discharge process of the lithium battery, while improving the lithium ion transmission efficiency, and significantly improves the lithium battery production efficiency.

[0019] Other features and advantages of the lithium-inserting tape and battery provided by the present application will be further elaborated in the following specific embodiments. Description of the Drawings

[0020] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a cross-sectional schematic diagram of the lithium-inserting tape provided by the embodiment of the present application;

[0022] Figure 2 It is a cross-sectional schematic diagram of the lithium-inserting tape provided by the embodiment of the present application;

[0023] Figure 3 It is a cross-sectional schematic diagram of the lithium-inserting tape provided by the embodiment of the present application;

[0024] Figure 4 Schematic view of the lithium - intercalated tape provided by the embodiment of the present application from the perspective of the thickness direction;

[0025] Figure 5 Schematic view of the lithium - intercalated tape provided by the embodiment of the present application from the perspective of the thickness direction.

[0026] 100. Lithium - intercalated tape; T. Thickness direction;

[0027] 10. Porous substrate layer;

[0028] 20. Active coating;

[0029] 30. Conductive adhesive layer; 31. Ventilation cavity;

[0030] 40. Release layer. Detailed implementation manners

[0031] In the description of the present application, it should be understood that when terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" are used to indicate the orientation or positional relationship, without special instructions, it is understood as the orientation or positional relationship based on the drawings shown. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.

[0032] In addition, features defined with "first" and "second" are only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Features defined with "first" and "second" may explicitly or implicitly include at least one of the defined features. When the description of "a plurality" appears, generally it means at least two, such as two, three, etc., unless otherwise specifically defined.

[0033] In the present application, unless otherwise clearly specified and limited, when terms such as "installed", "connected", "connected to", "fixed" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0034] In the description of this specification, terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0035] As described above, the general concept of the embodiments of the present utility model is to provide a lithium-inserting tape 100. Through the structural design of the lithium-inserting tape 100, the active coating 20 for storing lithium and providing a pre-expansion space for the electrode sheet is integrated into the lithium-inserting tape 100, so that during the battery production process, it is only necessary to bond the lithium-inserting tape 100 to the surface of the electrode sheet, and there is no need to perform complex process steps such as coating, drying, and curing of the active coating 20, so as to improve the production efficiency of lithium batteries. And through the further optimized design of the layered structures such as the active coating 20 and the porous substrate layer 10, the lithium-inserting tape 100 is made to have better air permeability, so as to effectively improve the lithium-ion transmission efficiency during the charge and discharge process of the lithium battery.

[0036] Based on the above concept, referring to Figures 1 to 5 , an embodiment of this application provides a lithium-inserting tape 100, which is used to be attached to the negative electrode sheet and wound into a battery core together with the negative electrode sheet. The lithium-inserting tape 100 includes: a porous substrate layer 10; an active coating 20, formed on the surface of the porous substrate layer 10 along the thickness direction T. The active coating 20 has a porous structure and is arranged to be able to contact the surface of the negative electrode sheet; wherein, the thickness ratio of the active coating 20 to the porous substrate layer 10 is (1-20):1.

[0037] It should be understood that the lithium-inserting tape 100 provided by the embodiment of this application, as a lithium battery tape, integrates the active coating 20 for storing lithium and providing a pre-expansion space for the electrode sheet, and can be used for electrode winding and electrode sheet protection in the middle production processes (such as winding / stacking, shell welding, and sealing processes) of the lithium battery core. Compared with the method of coating, drying, and curing on the surface of the electrode sheet before the electrode sheet is wound, it is only necessary to bond the lithium-inserting tape 100 to the surface of the negative electrode sheet. The lithium-inserting tape 100 can be wound with the negative electrode sheet, the positive electrode sheet, and the separator to form a battery core, thereby simplifying the battery production process and improving the battery production efficiency.

[0038] In this embodiment, the porous substrate layer 10 serves as the carrier of the active coating 20, and both the porous substrate layer 10 and the active coating 20 have a porous structure, which can enable the lithium-insertion tape 100 to have higher adaptability to volume changes, facilitate the stress release of the electrode sheet, and also facilitate the improvement of the air permeability of the lithium-insertion tape 100. Moreover, the thickness ratio of the active coating 20 to the porous substrate layer 10 is 1-20:1. Since the active coating 20 needs to undertake the functions of storing lithium and providing a pre-expansion space for the electrode sheet, it has a higher thickness dimension than the porous substrate layer 10, so as to improve the lithium-ion transmission efficiency during the charge and discharge process of the lithium battery.

[0039] In addition, for the lithium-insertion tape 100 composed of the porous substrate layer 10 and the active coating 20, when the lithium-insertion tape 100 is bonded to the negative electrode sheet, the side of the active coating 20 facing away from the porous substrate layer 10 is in contact with the surface of the negative electrode sheet, so as to provide a pre-expansion space for the electrode sheets to squeeze and release stress when expanding, and store the excess lithium ions generated by the non-equivalent transmission of lithium ions at the interface of the negative electrode sheet at the bent part formed by the winding of the electrode sheet, alleviating the accumulation of lithium ions at the electrode sheet interface and avoiding the situation that lithium ions precipitate to form dendrites piercing the separator and damaging the cell structure.

[0040] It should be noted that the non-equivalent transmission of lithium ions is because the outer bending area of the bent part formed by the winding of the electrode sheet is much larger than the inner bending area. When lithium ions are transmitted along the radial direction of the cell, the lithium ions transmitted from the outer side of the electrode sheet to the inner side of the electrode sheet will accumulate at the inner interface of the electrode sheet. The active coating 20 can store this part of the accumulated lithium ions to avoid the formation of lithium precipitation and damage to the cell structure.

[0041] In addition, the thickness ratio of the active coating 20 to the porous substrate layer 10 is (1-20):1. The thickness ratio of the active coating 20 to the porous substrate layer 10 is appropriate. If the proportion of the thickness of the active coating 20 is too large, the lithium-ion transmission path will be too long, which is not conducive to the improvement of the lithium-ion transmission efficiency. If the proportion of the thickness of the active coating 20 is too small, the ability to store lithium and provide a pre-expansion space for the electrode sheet cannot be effectively exerted.

[0042] In the embodiment of the present application, the thickness ratio of the active coating 20 to the porous substrate layer 10 is (1-20):1. For example, the thickness ratio of the active coating 20 to the porous substrate layer 10 can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1 or any thickness ratio within the range of (1-20):1.

[0043] In the embodiments of the present application, the porous substrate layer 10 can be a separator or non-woven fabric. When the porous substrate layer 10 is a separator, the separator can be any one of a polypropylene separator, a polyethylene separator, a polyimide separator, or a polyvinylidene fluoride separator; when the porous substrate layer is a non-woven fabric, the non-woven fabric can be any one of a polypropylene non-woven fabric, a polyethylene non-woven fabric, a polyester non-woven fabric, or polytetrafluoroethylene.

[0044] In the embodiments of the present application, the active coating 20 can be formed by mixing and coating a conventional conductive particle and a binder of a pressure-sensitive hot-melt material on the porous substrate layer 10. The conductive particles can be selected from graphite, hard carbon, conductive carbon black, carbon nanotubes, graphene, etc. with a particle size less than 1 μm. These conductive particles all have a low resistivity, can effectively store lithium ions, and can conduct charge, meeting the lithium storage function of the active coating 20; the binder can be selected from water-based binders such as polyolefin resins, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl acrylate copolymers, ethylene-methacrylic acid copolymers, or polyvinylidene fluoride. The water-based binder can appropriately increase the viscosity by adding tackifying resins such as hydrogenated C5, hydrogenated C9 resins, hydrogenated C5 / C9 copolymer resins, hydrogenated DCPD, hydrogenated rosin, or hydrogenated polyterpene resins. The binder can also be selected from oil-based binders such as maleic anhydride-modified polypropylene resins, polyester resins, polyurethane thermoplastic elastomers, polyacrylate resins, or ethylene vinyl acetate copolymers, all of which can achieve uniform dispersion of the conductive particles and endow the active coating with the function of releasing the stress of the electrode sheet. By adjusting the ratio of the conductive particles and the binder, the lithium storage performance and the stress release performance of the active coating 20 for the electrode sheet can be flexibly adjusted.

[0045] In some embodiments, in order to form a high-quality active coating 20, a thickening agent, a dispersant, or an antifoaming agent can also be appropriately mixed during the preparation of the active coating 20. The thickening agent can enable the raw materials to stably adhere to the porous substrate layer 10 of the lithium-inserting tape 100 during the formation of the active coating 20; the dispersant is beneficial to promoting the dispersion of the conductive particles in the active coating 20, preventing particle aggregation and deposition, and promoting the uniform mixing of the particles and the binder medium; the antifoaming agent can avoid generating bubbles during the formation of the active coating 20 and reduce the impact of the bubbles on the lithium storage performance of the active coating 20.

[0046] The bonding temperature of the active coating 20 made of the binder of the above-listed olefin polymer emulsions is 50-100 °C. That is to say, for the lithium-inserting tape 100 composed of the porous substrate layer 10 and the active coating 20, the effective bonding of the lithium-inserting tape 100 and the negative electrode sheet can be achieved by hot-pressing the surface of the active coating 20 facing the negative electrode sheet at 50-100 °C.

[0047] It should be understood that the above porous substrate layer 10 and active coating 20 are both existing materials, and the embodiments of the present application are only examples and should not be construed as limiting the scope of protection.

[0048] refer to Figure 2 In order to further improve the adhesion ability of the lithium-intercalated tape 100 to the electrode sheet, in some embodiments, the lithium-intercalated tape 100 also includes: a conductive adhesive layer 30, formed on the side of the active coating 20 away from the porous substrate layer 10 along the thickness direction T, and the conductive adhesive layer 30 is used to bond with the surface of the negative electrode sheet; wherein the thickness of the conductive adhesive layer 30 is less than the thickness of the porous substrate layer 10, and the conductive adhesive layer 30 non-continuously covers the surface of the active coating 20.

[0049] It should be noted that the conductive adhesive layer 30 discontinuously covers the surface of the active coating 20, which means that there are spacing areas in the layered structure of the conductive adhesive layer 30, that is, the conductive adhesive layer 30 does not completely and evenly cover the entire surface of the active coating 20, but exists in a discontinuous and partial covering manner.

[0050] Since the active coating 20 needs to assume the functions of storing lithium and providing pre-expansion space, a higher lithium storage capacity is required in some application scenarios with higher active batteries, and the content of conductive particles is relatively high, which will make the adhesive account for a smaller proportion, and the bonding performance of the active coating 20 is relatively reduced. It is easy to peel off from the surface of the negative electrode sheet during the battery cycle. In this regard, the embodiment of the present application further designs a conductive adhesive layer 30 on the side of the active coating 20 away from the porous substrate layer 10 along the thickness direction T. Thus, the lithium-embedded tape 100 is a three-layer structure composed of a porous substrate layer 10, an active coating 20 and a conductive adhesive layer 30 stacked in sequence. The conductive adhesive layer 30 does not need to assume the lithium storage function, but only needs to ensure that lithium ions can be smoothly transmitted. Therefore, it can have higher bonding performance. During the process of bonding the negative electrode sheet, the lithium-embedded tape 100 is mainly in contact and bonding with the negative electrode sheet by the conductive adhesive layer 30.

[0051] The thickness of the conductive adhesive layer 30 is much lower than that of the active coating 20, and its purpose is to shorten the lithium ion transmission path so that the lithium ions can migrate between the positive and negative electrodes more efficiently to ensure the lithium ion transmission efficiency. At the same time, in order to avoid affecting the air permeability of the lithium embedded tape 100, the conductive adhesive layer 30 is discontinuously covered on the surface of the active coating 20. Compared with continuously covering the surface of the active coating 20, this design can improve the air permeability of the lithium embedded tape 100 with the conductive adhesive layer 30, and reduce the transmission medium that needs to be passed through during the lithium ion transmission process, so as to ensure the bonding performance, lithium storage performance and pre-expansion space performance of the lithium embedded tape 100, while achieving an effective improvement in the lithium ion transmission efficiency.

[0052] In the conductive adhesive layer 30 in the embodiments of the present application, conductive particles of the same material as those in the active coating 20 may be present, but the proportion of the conductive particles in the conductive adhesive layer 30 is much lower than that in the active coating 20, so that the conductive adhesive layer 30 can achieve lithium ion transmission while having higher bonding performance. For example, if the mass proportion of the conductive particles in the active coating 20 is 60-98%, the mass proportion of the conductive particles in the conductive adhesive layer 30 can be 5-30%.

[0053] In the embodiments of the present application, the conductive adhesive layer 30 can select the same adhesive as the active coating 20 according to different application scenarios to achieve adhesion to the negative electrode sheet under the hot pressing conditions at a specific temperature, or can select an adhesive with viscosity at room temperature (such as polyacrylate resin) to achieve direct adhesion to the negative electrode sheet at room temperature, further simplifying the battery production process.

[0054] To achieve the discontinuous design of the conductive adhesive layer 30, in some embodiments, the conductive adhesive layer 30 is provided with a plurality of through ventilation cavities 31 along the thickness direction T, so that at least part of the active coating 20 facing the conductive adhesive layer 30 is exposed.

[0055] It can be understood that the plurality of ventilation cavities 31 directly penetrate the conductive adhesive layer 30 along the thickness direction T, so that part of the surface of the active coating 20 between the conductive adhesive layer 30 and the porous substrate layer 10 facing the conductive adhesive layer 30 is exposed. This design significantly reduces the coverage area of the conductive adhesive layer 30 on the active coating 20, so that while ensuring that the conductive adhesive layer 30 can be bonded to the negative electrode sheet, lithium ions can be directly transmitted into the active coating 20 through the ventilation cavities 31, thereby significantly improving the lithium ion transmission efficiency.

[0056] To improve the air permeability of the lithium-inserting tape 100, the plurality of ventilation cavities 31 in the conductive adhesive layer 30 are arranged in an array, and the plurality of ventilation cavities 31 are in a groove shape and / or a hole shape. In the embodiments of the present application, the ventilation cavities 31 are arranged in an array, which can improve the air permeability of the lithium-inserting tape 100, promote the lithium ion transmission efficiency, and at the same time improve the volume change adaptability of the lithium-inserting tape 100, further providing a buffer space for the volume change of the electrode sheet, thereby further suppressing the occurrence of lithium deposition phenomenon.

[0057] The plurality of ventilation cavities 31 are in a groove shape and / or a hole shape, that is, the plurality of ventilation cavities 31 can all be in a groove shape or all be in a hole shape, and the specific shape can be flexibly designed. For example, the design of the plurality of ventilation cavities 31 can make the conductive adhesive layer 30 cover the surface of the active coating 20 in a patterned manner. When the plurality of ventilation cavities 31 are all circular holes (refer to Figure 4 ), the pattern of the conductive adhesive layer 30 can be a dot-like spaced pattern. When the plurality of ventilation cavities 31 are all square grooves (refer to Figure 5), the pattern of the conductive adhesive layer 30 may be a linear spaced pattern, and when the plurality of air-permeable cavities 31 are all square holes, the pattern of the conductive adhesive layer 30 may be a grid pattern.

[0058] In order to achieve a balance between the bonding performance and the air permeability of the lithium-embedded tape 100, the coverage area of ​​the conductive adhesive layer 30 on the active coating 20 accounts for 10 to 50% of the total area of ​​the active coating 20 facing the conductive adhesive layer 30. In other words, the area occupied by the air-permeable cavity 31 is 50 to 90% of the total area of ​​the active coating 20 facing the conductive adhesive layer 30, so as to ensure the bonding performance of the lithium-embedded tape 100 while improving the air permeability of the lithium-embedded tape 100, so as to facilitate the efficient transmission of lithium ions.

[0059] In some embodiments, the porosity of the active coating 20 is set to 25-80%; the porosity of the porous substrate layer 10 is set to 30-85%, and the pore size is set to ≤10μm. The porous substrate layer 10 and the active coating 20 are designed within this range, and both have a higher porosity, so that the lithium-embedded tape 100 has a higher adaptability to volume changes, which is beneficial to the stress release of the pole piece, and is also beneficial to the effective improvement of the air permeability of the lithium-embedded tape 100 in the battery cell, which promotes the lithium ion transmission efficiency to be further improved.

[0060] When the conductive adhesive layer 30 is sticky at room temperature, in order to prevent dust and foreign matter from affecting the adhesion of the conductive adhesive layer 30 during storage and transportation of the lithium embedded tape 100, in some embodiments, reference Figure 3 The lithium-embedded tape 100 also includes a release layer 40; the release layer 40 can be coated on a side of the porous substrate layer 10 that is away from the active coating 20 along the thickness direction T, or can be peeled off and arranged on a side of the conductive adhesive layer 30 that is away from the active coating 20 along the thickness direction T, so that after the lithium-embedded tape 100 is wound into a roll, the conductive adhesive layer 30 can be covered by the release layer 40. When the lithium-embedded tape 100 is used, the conductive adhesive layer 30 and the release layer 40 can be directly peeled off to avoid affecting the bonding performance of the lithium-embedded tape 100 during storage and transportation, thereby ensuring the bonding performance of the lithium-embedded tape 100 when bonding with the electrode.

[0061] In some embodiments, the overall thickness of the lithium embedded tape 100 is 20-150 μm. If the lithium embedded tape 100 is too thick, the battery active material in the battery cell will occupy too little space, affecting the battery capacity. The overall thickness of the lithium embedded tape 100 is 20-150 μm, which can give full play to the performance of the lithium embedded tape 100 while avoiding affecting the battery capacity.

[0062] In some embodiments, the thickness of the porous substrate layer 10 is 5-50 μm. For example, the thickness of the porous substrate layer 10 can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or any thickness value within the range of 5-50 μm.

[0063] In some embodiments, the thickness of the active coating layer 20 is 5-100 μm. For example, the thickness of the active coating layer 20 can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, or any thickness value within the range of 5-100 μm.

[0064] In some embodiments, the thickness of the conductive adhesive layer 30 is less than 10 μm. For example, the thickness of the conductive adhesive layer 30 can be 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, or any thickness value within the range of 1-9 μm.

[0065] In some embodiments, the thickness of the release layer 40 is less than 1 μm. For example, the thickness of the release layer 40 can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or any thickness value within the range of 0.1-0.9 μm.

[0066] A specific embodiment of the present application provides a lithium-inserting tape 100, which includes a laminated porous substrate layer 10 and an active coating layer 20. Among them, the porous substrate layer 10 has a thickness of 20±0.2 μm and has a porous structure directly provided by the porous substrate. The porous substrate is a porous polypropylene film with a pore size of 0.05-1 μm and a porosity of about 60%; the active coating layer 20 is formed on the surface of the porous substrate layer 10 along the thickness direction T, with a thickness of 30±0.2 μm, and has a porous structure, which is obtained by uniformly mixing an olefin polymer emulsion, conductive particles, and functional additives and then coating.

[0067] Another specific embodiment of the present application provides a lithium-embedded tape 100, which includes a porous substrate layer 10, an active coating layer 20 and a conductive adhesive layer 30 stacked in sequence, wherein the porous substrate layer 10 has a thickness of 20±0.2 μm and has a porous structure, and the porous structure is directly provided by the porous substrate, and the porous substrate is a porous polypropylene film with a pore size of 0.05-1 μm and a porosity of about 60%; the active coating layer 20 is formed on the surface of the porous substrate layer 10 along the thickness direction T, and has a thickness of 40±0 .2μm, with a porous structure, obtained by coating after uniformly mixing an olefin polymer emulsion, conductive particles and functional additives; the conductive adhesive layer 30, with a thickness of 1μm, is obtained by uniformly mixing an olefin polymer emulsion and conductive particles and then spraying, and is formed on the side of the active coating 20 away from the porous substrate layer 10 along the thickness direction T, and the conductive adhesive layer 30 is provided with a plurality of through-going air-permeable cavities 31 along the thickness direction T, and the coverage area thereof accounts for 30% of the total area of ​​the active coating 20 facing the conductive adhesive layer 30.

[0068] Another specific embodiment of the present application provides a lithium-embedded tape 100, which includes a release layer 40, a porous substrate layer 10, an active coating 20 and a conductive adhesive layer 30 stacked in sequence, wherein the release layer 40 has a thickness of 0.5 μm and is coated on the side of the porous substrate layer 10 away from the active coating 20; the porous substrate layer 10 has a thickness of 20±0.2 μm and has a porous structure, and the porous structure is directly provided by the porous substrate, and the porous substrate is a porous polypropylene film with a pore size of 0.05-1 μm and a porosity of about 60%; the active coating 20 is formed on the porous substrate layer 10. The surface of the substrate layer 10 along the thickness direction T has a thickness of 40±0.2μm and a porous structure, and is obtained by coating after evenly mixing polyacrylate resin, conductive particles and functional additives; the conductive adhesive layer 30 has a thickness of 1μm, and is obtained by evenly mixing olefin polymer emulsion and conductive particles and then spraying, and is formed on the side of the active coating 20 away from the porous substrate layer 10 along the thickness direction T. The conductive adhesive layer 30 is provided with a plurality of through-ventilated cavities 31 along the thickness direction T, and the coverage area thereof accounts for 30% of the total area of ​​the active coating 20 facing the conductive adhesive layer 30.

[0069] Another embodiment of the present application further provides a battery, comprising the lithium embedded tape 100 mentioned above.

[0070] In some embodiments, the battery further includes a positive electrode sheet, a separator and a negative electrode sheet; the lithium-embedded tape 100 is bonded to at least one side of the negative electrode sheet along the thickness direction T, and the positive electrode sheet, the separator and the negative electrode sheet bonded with the lithium-embedded tape 100 are stacked in sequence and wound to form a battery cell.

[0071] In this embodiment, the negative electrode sheet can be double-sidedly embedded with the lithium-embedded tape 100 along the thickness direction T. The battery cell structure sequentially includes a positive electrode sheet, a separator, the lithium-embedded tape 100, a negative electrode sheet, and the lithium-embedded tape 100 from the inside to the outside; the negative electrode sheet can also be single-sidedly embedded with the lithium-embedded tape 100 along the thickness direction T. The battery cell structure sequentially includes a positive electrode sheet, a separator, the lithium-embedded tape 100, and a negative electrode sheet from the inside to the outside.

[0072] The lithium-embedded tape 100 is integrally attached to the surface of the negative electrode sheet facing the thickness direction T. In some embodiments, the lithium-embedded tape 100 can be attached only to the surface of the bent portion during the process of winding the negative electrode sheet into a battery cell along the thickness direction T, so as to reduce the coverage area of the lithium-embedded tape 100 on the non-bent portion of the negative electrode sheet, ensure that the electrode sheet can release stress at the bent portion, and further improve the lithium ion transmission efficiency during the charge and discharge process of the battery.

[0073] In summary, through the structural design of the lithium-embedded tape 100, the embodiment of the present application effectively alleviates the lithium precipitation phenomenon during the charge and discharge process of the lithium battery, improves the lithium ion transmission efficiency, and significantly improves the production efficiency of the lithium battery.

[0074] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A lithium-embedded tape, characterized in that: The lithium-embedded adhesive tape (100) is used for bonding with the negative electrode sheet and rolling with the negative electrode sheet to form a battery cell, and comprises: A porous substrate layer (10); An active coating (20) is formed on the surface of the porous substrate layer (10) along the thickness direction (T), and the active coating (20) has a porous structure and is configured to be in contact with the surface of the negative electrode sheet; Wherein, the thickness ratio of the active coating layer (20) to the porous substrate layer (10) is (1-20):

1.

2. The lithium-embedded tape according to claim 1, characterized in that: Also includes: A conductive adhesive layer (30) is formed on a side of the active coating layer (20) that is away from the porous substrate layer (10) along the thickness direction (T), and the conductive adhesive layer (30) is used to bond and adhere to the surface of the negative electrode sheet; The thickness of the conductive adhesive layer (30) is less than the thickness of the porous substrate layer (10), and the conductive adhesive layer (30) is discontinuously covered on the surface of the active coating layer (20).

3. The lithium-embedded tape according to claim 2, characterized in that: The conductive adhesive layer (30) is provided with a plurality of through-going air-permeable cavities (31) along the thickness direction (T), so that the active coating (20) is at least partially exposed in the direction of the conductive adhesive layer (30).

4. The lithium-embedded tape according to claim 3, characterized in that: The plurality of air-permeable cavities (31) are arranged in an array, and the plurality of air-permeable cavities (31) are in the shape of grooves and / or holes.

5. The lithium-embedded tape according to claim 2, characterized in that: The coverage area of ​​the conductive adhesive layer (30) on the active coating (20) accounts for 10 to 50% of the total area of ​​the active coating (20) facing the conductive adhesive layer (30).

6. The lithium-intercalated tape according to any one of claims 1 to 5, characterized in that: The porosity of the active coating (20) is set to 25-80%; and / or The porosity of the porous substrate layer (10) is set to 30-85%, and the pore size is set to ≤10 μm.

7. The lithium-embedded tape according to claim 2, characterized in that: The lithium-embedded adhesive tape (100) further includes a release layer (40); The release layer (40) can be coated on a side of the porous substrate layer (10) that is away from the active coating layer (20) along the thickness direction (T), or can be peeled off and arranged on a side of the conductive adhesive layer (30) that is away from the active coating layer (20) along the thickness direction (T).

8. The lithium-embedded tape according to claim 7, characterized in that: The overall thickness of the lithium-embedded tape (100) is 20-150 μm; wherein, The porous substrate layer (10) has a thickness of 5-50 μm; and / or The active coating (20) has a thickness of 5-100 μm; and / or The conductive adhesive layer (30) has a thickness of less than 10 μm; and / or The release layer (40) has a thickness of less than 1 μm.

9. A battery, characterized in that: It comprises the lithium-intercalated tape (100) as claimed in any one of claims 1 to 8.

10. The battery according to claim 9, characterized in that The battery also includes a positive electrode sheet, a separator and a negative electrode sheet; The lithium-embedded adhesive tape (100) is bonded to at least one side of the negative electrode sheet along the thickness direction (T), and the positive electrode sheet, the separator and the negative electrode sheet bonded with the lithium-embedded adhesive tape (100) are sequentially stacked and rolled to form a battery cell.

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