Battery protection double-sided adhesive tape and battery using same

Abstract

The application provides a battery protection double-sided adhesive tape and a battery using the same. The battery protection double-sided adhesive tape comprises a first adhesive layer, a protection function layer and a second adhesive layer which are sequentially stacked. The protection function layer comprises a first support layer and a second support layer. A connecting layer is further arranged between the first support layer and the second support layer. The glass transition temperature T g of the connecting layer is not lower than -25 DEG C. The connecting layer comprises a reactive polymer substance, and the mass content of the reactive polymer substance in the connecting layer is not lower than 60%. The reactive polymer substance is selected from at least one polymer of A to D. The structural formula of polymer A is shown in the description. The structural formula of polymer B is shown in the description. R is independently selected from at least one of H and CH3. R' is independently selected from at least one of H, CH3, CH2CH3 and CH2(CH2)CH3. The structural formula of polymer C is shown in the description. Polymer D is obtained by polycondensation reaction of isocyanate with a polyol, and the functionality of the isocyanate is at least 2 and the functionality of the polyol is at least 2.

Description

Technical Field

[0001] This invention belongs to the field of batteries, and particularly relates to a battery protection double-sided adhesive tape and a battery using the same. Background Technology

[0002] Rechargeable batteries are characterized by high operating voltage, high energy density, low self-discharge, multiple cycle life, long service life, and high environmental friendliness, and are widely used in mobile phones, automobiles, laptops, and other fields. In existing rechargeable battery products, the battery terminals and the outer packaging film are generally fixed together by double-sided tape. Typically, the outer packaging film for the battery terminals is aluminum-plastic film, while the bonding surface of the battery terminals is aluminum foil or polyethylene separator. The toughness and strength of the aluminum-plastic film are significantly higher than those of the bonding surface of the battery terminals. Therefore, during a drop test, the tensile force exerted by the aluminum-plastic film on the double-sided tape is greater than the tensile force exerted by the bonding surface of the battery terminals on the double-sided tape. This difference in tensile force can easily cause the side of the double-sided tape adhered to the battery terminals to chip or tear. In more stringent drop tests, even aluminum foil tearing may occur, adversely affecting the drop resistance of the rechargeable battery.

[0003] With technological advancements, various fields are placing increasingly higher demands on rechargeable batteries, such as requiring higher energy density, more stable performance, and enhanced safety. Consequently, driven by the pursuit of higher energy density in rechargeable batteries, the current collectors are becoming increasingly thinner, decreasing from the previously used 6–10 μm aluminum foil thickness to 4–6 μm. This makes the current collectors more susceptible to burrs and tears during drops, thus affecting the stability and safety of the rechargeable battery. Therefore, further optimization of the stability and safety of rechargeable batteries is of paramount importance. Summary of the Invention

[0004] To improve the drop resistance of batteries, this invention provides a battery protection double-sided adhesive tape and a battery using the same.

[0005] According to one aspect of the present invention, a battery protection double-sided adhesive tape is provided, comprising a first adhesive layer, a protective functional layer, and a second adhesive layer sequentially stacked; the protective functional layer comprises a first support layer and a second support layer; and a connecting layer is further provided between the first support layer and the second support layer, the glass transition temperature Tg of the connecting layer being ≥ -25℃; the connecting layer comprises a reactive polymer, and the mass content of the reactive polymer in the connecting layer is not less than 60%; the reactive polymer is selected from at least one polymer from A to D below, wherein the structural formula of polymer A is [insert structural formula here]. The structural formula of polymer B is R is independently selected from at least one of H and CH3; R' is independently selected from at least one of H, CH3, CH2CH3, and CH2(CH2)CH3; the structural formula of polymer C is Polymer D is obtained by polycondensation reaction of an isocyanate with a functionality of at least 2 and a polyol with a functionality of at least 2.

[0006] This invention, by selecting at least one polymer from A to D, enables the battery protection double-sided adhesive to exhibit responsive viscosity changes. Specifically, when the battery protection double-sided adhesive provided by this invention is immersed in an organic acid ester solution at 85°C for 4 hours, the peel force retention rate between the connecting layer and the first support layer and the second support layer does not exceed 80%. Furthermore, by controlling the glass transition temperature of the connecting layer to meet a specific range, this invention can improve the penetration of the electrolyte into the connecting layer, accelerate the decrease in the peel force of the connecting layer, thereby improving the battery's drop resistance and adapting to the development of the secondary battery industry. The glass transition temperature (GTE) is specified in the original text.

[0007] Preferably, the glass transition temperature T of the connecting layer g = -25℃~0℃.

[0008] Preferably, the area of ​​the connecting layer independently satisfies either a or b; a. the area of ​​the connecting layer is 20-70% of the first support layer; b. the area of ​​the connecting layer is 20-70% of the second support layer. Further, the area of ​​the connecting layer affects the peel force retention rate between the connecting layer and the first and second support layers, respectively. Specifically, if the area of ​​the connecting layer is too high, it will affect the penetration of the electrolyte; if the area of ​​the connecting layer is too low, it will affect the adhesion effect between the connecting layer and the first and second support layers, respectively.

[0009] Preferably, the bonding layer includes adhesive areas; the number of adhesive areas in the bonding layer is not less than 1; and the maximum diameter of the adhesive areas is 0.1 to 1 mm; the concentricity between the adhesive areas is 0.2 to 2 mm.

[0010] Preferably, a blank portion is provided between the first support layer and the second support layer; the blank portion and the connecting layer are on the same plane, and the blank portion and the connecting layer are parallel to the first support layer and the second support layer; wherein, the connecting layer is composed of a rectangular adhesive area with a width of 1 to 5 mm and a number greater than or equal to 1, and the blank portion is composed of a rectangular non-adhesive area with a width of 1 to 5 mm and a number greater than or equal to 1; and the rectangular non-adhesive area and the rectangular adhesive area are spaced apart.

[0011] Preferably, the connecting layer further includes an adhesive substance with a mass content not exceeding 50%, the adhesive substance including at least one selected from rosin resin, terpene phenol resin, and petroleum resin. In this invention, the glass transition temperature of polymer A is 60–70°C, the glass transition temperature of polymer B is -30–-45°C, the glass transition temperature of polymer C is -10–15°C, and the glass transition temperature of polymer D is 45–60°C. In this invention, the sensitivity of the battery protection double-sided adhesive tape to responsive viscosity changes is improved by introducing an adhesive substance.

[0012] Preferably, the mass content of the adhesive substance in the bonding layer is 20-50%.

[0013] Preferably, the connecting layer further includes a curing agent with a mass content of no more than 3%, the curing agent including at least one of amino resin and pyridine. Furthermore, by introducing the curing agent, on the one hand, it can promote the formation of a strong three-dimensional network of polymer B, preventing the formed connecting layer from dissolving in the electrolyte and affecting its electrochemical performance; on the other hand, it can further accelerate the decrease in the peel force of the connecting layer, improving the battery's drop resistance.

[0014] Preferably, the first adhesive layer comprises 40-80% functional polymer A and 18-50% hydrogenated petroleum resin by weight percentage; wherein, functional polymer A includes at least one of styrene-isoprene-styrene block copolymer (SIS), polystyrene-polybutadiene-styrene block copolymer (SBS), styrene-butadiene rubber (SBR), hydrogenated styrene-polybutadiene-styrene block copolymer (SEBS), amorphous α-olefin copolymer (APAO), polyolefin elastomer (POE), polypropylene (PP), and polyisobutylene (PIB). The first adhesive layer provided by the present invention has pressure sensitivity, high peel strength after contact with the surface of the battery cell, and good electrolyte resistance.

[0015] Preferably, the softening point of the hydrogenated petroleum resin is between 100 and 150°C.

[0016] Preferably, the first adhesive layer further includes pigment, wherein the pigment content is not higher than 20% by mass.

[0017] Preferably, the pigment includes at least one of phthalocyanine blue, titanium dioxide, inorganic cobalt blue, and inorganic cobalt green.

[0018] Preferably, the second adhesive layer comprises 80-95% functional polymer B and 5-20% hydrogenated petroleum resin by weight percentage; wherein the functional polymer B includes at least one of styrene-isoprene-styrene block copolymer (SIS), polystyrene-polybutadiene-styrene block copolymer (SBS), styrene-butadiene rubber (SBR), hydrogenated styrene-polybutadiene-styrene block copolymer (SEBS), amorphous α-olefin copolymer (APAO), polyolefin elastomer (POE), polypropylene (PP), and polyisobutylene (PIB). The second adhesive layer provided by the present invention is heat-sensitive, exhibits high peel strength after contact with the battery's protective layer, and has good electrolyte resistance.

[0019] Preferably, the softening point of the hydrogenated petroleum resin is between 100 and 150°C.

[0020] Preferably, the thickness of the bonding layer is 1 to 3 μm; and / or, the thickness of the first adhesive layer is 2 to 4 μm; and / or, the thickness of the second adhesive layer is 3 to 6 μm.

[0021] Preferably, the first support layer comprises at least one of polyethylene terephthalate (PET), polyimide (PI), and polypropylene (PP).

[0022] Preferably, the second support layer comprises at least one of polyethylene terephthalate (PET), polyimide (PI), and polypropylene (PP).

[0023] In a second aspect, the present invention provides a battery comprising a cell, a protective layer, and a battery protective double-sided tape as described above; wherein a first adhesive layer is attached to the surface of the cell, and the inner surface of the protective layer is adhered to a second adhesive layer.

[0024] Preferably, the protective layer includes at least one of aluminum-plastic film, steel shell, aluminum shell, and plastic shell. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the battery protection double-sided adhesive tape provided in Embodiment 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the battery structure provided in Embodiment 1 of the present invention;

[0027] Figure 3 This is a schematic diagram of another battery structure provided in Embodiment 1 of the present invention;

[0028] Figure 4 This is a schematic diagram of the battery protection double-sided tape wrapped in a U-shape around the edge of the battery cell in the battery provided in Embodiment 1 of the present invention;

[0029] Figure 5This is a schematic diagram of the adhesive area of ​​the connecting layer of the battery protection double-sided tape provided in Embodiment 11 of the present invention;

[0030] Figure 6 This is a schematic diagram of the connecting layer and the blank portion in the battery protection double-sided tape provided in Embodiment 12 of the present invention;

[0031] The meanings of the above figure labels are as follows:

[0032] 1. Battery cell; 11. First surface; 12. Second surface;

[0033] 2. Battery protection double-sided tape; 21. First adhesive layer; 22. First support layer; 23. Connecting layer; 231. Adhesive area; 232. Unadhesive area; 24. Second support layer; 25. Second adhesive layer; Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0035] Example 1

[0036] 1. Preparation of battery protection double-sided adhesive tape

[0037] The raw materials required for preparing the battery protection double-sided adhesive tape 2 in this embodiment are shown in Table 1.

[0038] Specifically, in this embodiment, the battery protection double-sided tape 2 is prepared as follows: A coating process is used to coat the adhesive of the first adhesive layer 21 onto the surface of the release film, forming the first adhesive layer 21; then, the first support layer 22 is bonded to the side of the first adhesive layer 21 away from the release film; the adhesive of the connecting layer 23 is coated onto the surface of the first support layer 22 away from the first adhesive layer 21, forming the connecting layer 23, and then the second support layer 24 is bonded; the adhesive of the second adhesive layer 25 is coated onto the side of the second support layer 24 away from the connecting layer 23, forming the second adhesive layer 25, thus obtaining the battery protection double-sided tape 2. Figure 1 As shown.

[0039] Table 1. Raw materials required for this embodiment

[0040]

[0041] 2. Battery manufacturing

[0042] A battery cell is formed by stacking or winding a separator, a negative electrode, and a positive electrode together. The battery cell 1 is fixed to the outside with the aforementioned battery protection double-sided tape 2. Then, it is heat-pressed and sealed with an aluminum-plastic film, and then formed into a battery through drying, liquid injection, formation and other steps.

[0043] In this battery, cell 1 is wrapped in a packaging film, see [link / reference]. Figure 2 and Figure 3 As shown, the battery cell 1 includes a first surface 11 and a second surface 12 facing away from each other. Battery protection double-sided tape 2 is attached to the four edges of the battery cell 1. A first adhesive layer 21 simultaneously adheres to both the first surface 11 and the second surface 12, so that the battery protection double-sided tape 2 wraps around the four edges of the battery cell 1 in a U-shape. One side of the first adhesive layer 21 of the battery protection double-sided tape 2 is attached to the surface of the battery cell 1, and one side of the second adhesive layer 25 is attached to the surface of the aluminum-plastic film. Figure 4 As shown.

[0044] The aluminum foil in the battery cell is 4 μm thick, and the area of ​​the connecting layer 23 is exactly the same as that of the first support layer 22 and the second support layer 24. Furthermore, the electrolyte used contains 12.5% ​​lithium salt (1 mol / L LiPF6) by mass and 87.5% organic solvent by mass; the mass ratio of ethylene carbonate: propylene carbonate: diethyl carbonate: ethyl propionate in the organic solvent is 30:10:30:30.

[0045] Example 2

[0046] This embodiment refers to the formulation and method provided in Example 1 to prepare battery protection double-sided tape and the battery using it. The difference from Example 1 is that in this embodiment, when preparing battery protection double-sided tape, polymer C is used instead of polymer A in equal parts by mass. Apart from the above differences, the operation steps for preparing battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 1.

[0047] Example 3

[0048] This embodiment refers to the formulation and method provided in Example 1 to prepare battery protection double-sided tape and the battery using it. The difference from Example 1 is that in this embodiment, when preparing battery protection double-sided tape, polymer D is used instead of polymer A in equal parts by mass. Apart from the above differences, the operation steps for preparing battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 1.

[0049] Example 4

[0050] This embodiment refers to the formulation and method provided in Example 1 to prepare battery protection double-sided tape and the battery using it. The difference from Example 1 is that in this embodiment, when preparing battery protection double-sided tape, the formulation for preparing connecting layer 23 is 98% polymer B and 2% pyridine nitrogen by mass percentage. Apart from the above differences, the operation steps for preparing battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 1.

[0051] Example 5

[0052] This embodiment refers to the formula and method provided in Embodiment 4 to prepare battery protection double-sided adhesive tape and the battery using it. The difference from Embodiment 4 is that in this embodiment, when preparing the battery protection double-sided adhesive tape, the T of the resulting connecting layer 23 is... g =10℃. Apart from the differences mentioned above, the operational steps for preparing the battery protection double-sided adhesive tape and the battery using it in this embodiment are strictly consistent with those in Example 4. Specifically, in this embodiment, the formulation of the connecting layer 23 is: 77.5% polymer B, 2.5% amino resin, and 22% petroleum resin, to bond the connecting layer 23 to T... g The value was adjusted from -23℃ to 10℃.

[0053] Example 6

[0054] This embodiment refers to the formulation and method provided in Example 4 to prepare battery protection double-sided tape and the battery using it. The difference from Example 4 is that in this embodiment, the Tg of the resulting connecting layer 23 is 0°C. Apart from the above difference, the operation steps for preparing the battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 4. Specifically, in this embodiment, the formulation of the connecting layer 23 is: 98.6% polymer B, 1.3% amino resin, and 0.1% terpene phenol resin, to achieve a Tg of 0°C for the connecting layer 23. g The value was adjusted from -23℃ to 0℃.

[0055] Example 7

[0056] This embodiment refers to the formulation and method provided in Example 4 to prepare battery protection double-sided tape and the battery using it. The difference from Example 4 is that in this embodiment, the Tg of the connecting layer 23 is -25°C. Apart from the above difference, the operation steps for preparing the battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 4. Specifically, in this embodiment, the formulation of the connecting layer 23 is: 99.6% polymer B, 0.3% pyridine nitrogen, and 0.1% rosin resin, to achieve a Tg of -25°C for the connecting layer 23. g The value was adjusted from -23℃ to -25℃.

[0057] Example 8

[0058] This embodiment refers to the formulation and method provided in Example 4 to prepare battery protection double-sided tape and the battery using it. The difference from Example 4 is that in this embodiment, an amino resin of equal mass fraction is used instead of nitrogen pyridine when preparing battery protection double-sided tape. Apart from the above differences, the operation steps for preparing battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 4.

[0059] Example 9

[0060] This embodiment refers to the formulation and method provided in Example 1 to prepare battery protection double-sided tape and the battery using it. The difference from Example 1 is that in this embodiment, terpene phenol resin of equal mass fraction is used instead of rosin resin when preparing battery protection double-sided tape. Apart from the above differences, the operation steps for preparing battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Example 1.

[0061] Example 10

[0062] This embodiment refers to the formula and method provided in Embodiment 1 to prepare battery protection double-sided tape and the battery using it. The difference from Embodiment 1 is that in this embodiment, petroleum resin is used instead of rosin resin in the preparation of battery protection double-sided tape with an equal mass fraction. Apart from the above differences, the operation steps for preparing battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Embodiment 1.

[0063] Example 11

[0064] This embodiment refers to the formula and method provided in Embodiment 4 to prepare battery protection double-sided tape and the battery using it. The difference from Embodiment 4 is that in this embodiment, the area of ​​the connecting layer 23 obtained during the preparation of the battery protection double-sided tape is 60% of the area of ​​the first support layer 22. Apart from the above differences, the operation steps for preparing the battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Embodiment 1. Specifically, in this embodiment, the connecting layer 23 includes adhesive areas 231, the number of adhesive areas 231 is not less than 1, and the maximum diameter of the adhesive area is 0.5 mm; the concentricity between the adhesive areas is 1 mm. A schematic diagram of the connecting layer 23 is shown below. Figure 5 As shown.

[0065] Example 12

[0066] This embodiment refers to the formula and method provided in Embodiment 4 to prepare battery protection double-sided tape and the battery using it. The difference from Embodiment 4 is that in this embodiment, the area of ​​the connecting layer 23 obtained during the preparation of the battery protection double-sided tape is 60% of the area of ​​the first support layer 22. Apart from the above difference, the operation steps for preparing the battery protection double-sided tape and the battery using it in this embodiment are strictly consistent with those in Embodiment 1. Specifically, in this embodiment, a blank portion is provided between the first support layer 22 and the second support layer 24; the blank portion and the connecting layer 23 are on the same plane, and the blank portion and the connecting layer 23 are parallel to the first support layer 22 and the second support layer 24; wherein, the connecting layer 23 is composed of at least one rectangular adhesive area 231 with a width of 2mm, and the blank portion is composed of at least one rectangular non-adhesive area 232 with a width of 2mm; the rectangular non-adhesive areas 231 and the rectangular adhesive areas 232 are spaced apart. A schematic diagram of the structure of the connecting layer 23 is shown below. Figure 6 As shown.

[0067] Comparative Example 1

[0068] This comparative example uses the formulation and method provided in Example 1 to prepare a battery protection double-sided tape and its application in a battery. The difference from Example 1 is that the battery protection double-sided tape used in this comparative example uses the formulation and proportion of the third pressure-sensitive adhesive layer provided in Example 3 of CN114958230B to prepare the connecting layer 23 (thickness 6 μm), and the aluminum foil thickness in the battery is 10 μm. Apart from the above differences, the operational steps for preparing the battery protection double-sided tape and its application in the battery in this comparative example are strictly consistent with those in Example 1. Specifically, in this comparative example, the formulation of the connecting layer 23 is: 80% ethylene vinyl acetate and 20% hydrogenated rosin resin.

[0069] Comparative Example 2

[0070] This comparative example uses the formulation and method provided in Example 1 to prepare a battery protection double-sided tape and its application in a battery. The difference from Example 1 is that the battery protection double-sided tape used in this comparative example uses the formulation and proportion of the third pressure-sensitive adhesive layer provided in Example 3 of CN114958230B to prepare the connecting layer 23 (thickness 6 μm). The thickness of the aluminum foil in the battery is 4 μm. Apart from the above differences, the operational steps for preparing the battery protection double-sided tape and its application in the battery in this comparative example are strictly consistent with those in Example 1. Specifically, in this comparative example, the formulation of the connecting layer 23 is: 80% ethylene vinyl acetate and 20% hydrogenated rosin resin.

[0071] Comparative Example 3

[0072] This comparative example prepares a battery protection double-sided adhesive tape and a battery using the same, referring to the formulation and method provided in Example 4. The difference between this comparative example and Example 4 is that, in preparing the battery protection double-sided adhesive tape, the Tt of the bonding layer 23 is...g = -45℃. Apart from the differences mentioned above, the operational steps for preparing the battery protection double-sided tape and the battery using it in this comparative example are strictly consistent with those in Example 4. Specifically, in this comparative example, the formulation of the connecting layer 23 is 99.8% polymer B, 0.1% pyridine nitrogen, and 0.1% rosin resin, to bond the T of the connecting layer 23... g The value was adjusted from -23℃ to -45℃.

[0073] Test case

[0074] 1. Test Object

[0075] The battery protection double-sided tapes and batteries prepared in Examples 1-12 and Comparative Examples 1-3.

[0076] 2. Testing Methods

[0077] (1) Drop resistance test:

[0078] ① 1.8m Vertical Drop Test: With all six sides and four corners of the lithium battery facing the ground, drop the battery vertically from a height of 1.8m. After the drop test, test the battery voltage. If the voltage change is less than 60mV, the battery passes; otherwise, it fails. If the battery smokes or catches fire, the battery fails.

[0079] ② 2m Vertical Drop Test: With all six sides and four corners of the lithium battery facing the ground, drop the battery vertically from a height of 2m. After the drop test, test the lithium battery voltage. If the voltage change is less than 60mV, it is considered passed; otherwise, it is considered failed. If the battery smokes or catches fire, it is considered failed.

[0080] The drop test pass rate is calculated according to formula (1).

[0081]

[0082] (2) Peeling force before immersion in electrolyte:

[0083] S1. The first support layer 22, the connecting layer 23 and the second support layer 24 are combined and used as the test object, and 5000NS tape is applied to the surface of the first support layer 22 and the second support layer 24.

[0084] S2. Next, use a Kejian tensile tester to clamp the 5000NS tapes placed on both sides of the test object to perform a peel force test. The peel speed is 50mm / min and the peel angle is 180°. Record the peel force data and take the average value of a 60mm segment after the reading stabilizes (if a severe sawtooth curve appears, take the average value of the maximum value of the curve every 10mm after stabilization). The judgment criterion is the average value of 5 parallel samples.

[0085] 3. Test Results and Analysis

[0086] The test results for this test case are shown in Table 2.

[0087] Comparative Examples 1 and 2 show that while existing protective tapes are suitable for thicker aluminum foils, their drop resistance significantly decreases as the battery industry strives for higher energy densities (aluminum foil thickness reduced from 10μm to 4μm). This indicates that existing protective tapes cannot meet the more stringent requirements of the battery industry. In practical applications, a peel force of ≥0.01 N / mm before immersion in electrolyte is sufficient to meet actual usage requirements. However, peel force tests of the connecting layer 23 in Comparative Examples 1 and 2 before immersion in electrolyte show that while the peel force meets practical requirements, it does not exhibit good drop resistance. This may be due to excessively high peel force before immersion in electrolyte, preventing it from responding quickly to viscosity changes.

[0088] As demonstrated in Examples 1-7 and Comparative Example 3, on the one hand, by controlling the type of reactive polymer introduced, the present invention can ensure that the connecting layer 23 exhibits responsive viscosity changes without affecting battery performance. On the other hand, by controlling the glass transition temperature of the connecting layer 23, the present invention can improve the penetration of the electrolyte into the connecting layer 23 and accelerate the decrease in the peel force of the connecting layer 23. This proves that the battery protective double-sided adhesive provided by the present invention can impart good drop resistance to the battery without affecting its electrical performance, adapting to the latest developments in the battery industry and enhancing the market competitiveness of enterprises.

[0089] Specifically, as shown in Examples 1-4, using different reactive polymers in the connecting layer 23 affects the battery's drop resistance and peel strength. This may be because different reactive polymers affect the electrolyte's penetration rate into the connecting layer 23. While Examples 1-3 exhibit good drop resistance, their low peel strength may lead to slippage between the connecting layer 23 and the first support layer 22 and the second support layer 24 during application.

[0090] Based on Examples 4-8, it is known that in the connecting layer 23, when the reactive polymer is polymer B, the glass transition temperature of the connecting layer 23 can be controlled by changing the content or type of curing agent used in the connecting layer 23. Data shows that the connecting layer 23 exhibits good drop resistance when its glass transition temperature is within a certain range. As the glass transition temperature of the connecting layer 23 decreases, its peel strength also increases, which helps to improve potential slippage problems between the connecting layer 23 and the first support layer 22 and the second support layer 24.

[0091] Similarly, by combining the data from Examples 1 and 9-10, it can be seen that the type of adhesive substance used in the connecting layer 23 affects the glass transition temperature of the connecting layer 23, and thus affects the sensitivity of the connecting layer 23 to responsive viscosity changes. Specifically, in the connecting layer 23, polymers A, C, and D can control the glass transition temperature of the connecting layer 23 by introducing the mass content and type of adhesive substance. Furthermore, the type of adhesive substance also affects the peel strength of the connecting layer 23.

[0092] Furthermore, using a non-full coating method to prepare the connecting layer 23 in the battery protection double-sided adhesive tape not only improves the adhesion between adhesive layers but also enhances electrolyte penetration. Data from Examples 4, 11, and 12 show that although the area of ​​the connecting layer 23 in Example 4 is larger, its drop resistance can be further improved through structural design. Additionally, although the effective area of ​​the connecting layer 23 is the same in Examples 11 and 12, different configurations affect the peel strength of the connecting layer 23.

[0093] Table 2. Test results for this test case

[0094]

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A battery protection double-sided adhesive tape, characterized in that: The battery protection double-sided tape includes a first adhesive layer, a protective functional layer, and a second adhesive layer stacked in sequence. The protective functional layer includes a first support layer and a second support layer; Furthermore, a connecting layer is provided between the first support layer and the second support layer, wherein the glass transition temperature of the connecting layer is -25℃≤T g ≤0℃; The connecting layer includes a reactive polymer and an adhesive substance, wherein the reactive polymer contains no less than 60% by mass in the connecting layer; the adhesive substance contains no more than 50% by mass in the connecting layer; and the adhesive substance includes at least one of rosin resin, terpene phenol resin, and petroleum resin. The reactive polymer is selected from at least one polymer from A to C below. The structural formula of polymer A is ; The structural formula of polymer B is R is independently selected from H and CH3; R' is independently selected from H, CH3, CH2CH3, and CH2CH2CH3. The structural formula of polymer C is .

2. The battery protection double-sided tape as described in claim 1, characterized in that: The area of ​​the connecting layer independently satisfies either a or b; a. The area of ​​the connecting layer is 20-70% of that of the first supporting layer; b. The area of ​​the connecting layer is 20-70% of that of the second support layer.

3. The battery protection double-sided tape as described in claim 1, characterized in that: The bonding layer includes an adhesive area; In the connecting layer, the number of adhesive areas is not less than 1; Furthermore, the maximum diameter of the adhesive area is 0.1~1mm; the concentricity between the adhesive areas is 0.2~2mm.

4. The battery protection double-sided tape as described in claim 1, characterized in that: A gap is also provided between the first support layer and the second support layer; The blank portion and the connecting layer are on the same plane, and the blank portion and the connecting layer are parallel to the first support layer and the second support layer; The connecting layer consists of one or more rectangular adhesive areas with a width of 1 to 5 mm, and the blank area consists of one or more rectangular non-adhesive areas with a width of 1 to 5 mm. Furthermore, the rectangular glue-free area and the rectangular glued area are spaced apart.

5. The battery protection double-sided tape as described in claim 1, characterized in that: The connecting layer also includes a curing agent with a mass content of no more than 3%, wherein the curing agent includes at least one of amino resin and pyridine.

6. The battery protection double-sided tape as described in claim 1, characterized in that: The first adhesive layer comprises 40-80% functional polymer A and 18-50% hydrogenated petroleum resin by weight percentage. The functional polymer A includes at least one of styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-butadiene rubber, hydrogenated styrene-polybutadiene-styrene block copolymer, amorphous α-olefin copolymer, polypropylene, and polyisobutylene.

7. The battery protection double-sided tape as described in claim 1, characterized in that: The second adhesive layer comprises 80-95% functional polymer B and 5-20% hydrogenated petroleum resin by weight percentage. The functional polymer B includes at least one of styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-butadiene rubber, hydrogenated styrene-polybutadiene-styrene block copolymer, amorphous α-olefin copolymer, polypropylene, and polyisobutylene.

8. The battery protection double-sided tape as described in any one of claims 1 to 7, characterized in that: The thickness of the connecting layer is 1~3μm; And / or, the thickness of the first adhesive layer is 2~4μm; And / or, the thickness of the second adhesive layer is 3~6μm.

9. A battery, characterized in that, The battery includes a cell, a protective layer, and a battery protective double-sided adhesive tape as described in any one of claims 1 to 8; wherein, a first adhesive layer is attached to the surface of the cell, and the inner surface of the protective layer is bonded to a second adhesive layer.

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