A battery

Abstract

The application provides a battery, which comprises a battery cell, an outer package, and a battery protection double-sided adhesive tape connecting the battery cell and the outer package. The battery protection double-sided adhesive tape comprises a surface adhesive layer and a substrate. The two sides of the substrate are respectively combined with a layer of the surface adhesive layer. The raw material for preparing the surface adhesive layer comprises 50-95 parts of a main body resin, 1-50 parts of an adhesion resin, and 0-5 parts of a curing agent. The main body resin comprises a modified ternary ethylene-propylene rubber with grafted functional groups. The functional groups comprise carboxyl and / or hydroxyl. The curing agent comprises at least one of an amino resin, a nitrogen pyridine, and an isocyanate. The battery uses the battery protection double-sided adhesive tape to well adhere the battery cell and the outer package. The battery protection double-sided adhesive tape can not only fix the parts in the battery cell, but also reduce the possibility of relative displacement of the battery cell and the outer package in the battery liquid injection, formation and other stages.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular, relates to a battery. Background Art

[0002] Adhesive tape products are widely used in all aspects of battery production. In existing battery products, adhesive tape products are often used to secure the battery electrode assembly to its outer packaging. This helps improve the uniformity of the battery formation process and the stability of the cells, preventing them from shifting or deforming during the formation process. It also helps improve the battery's drop resistance, preventing edge collapse and tearing of the electrode assembly during drop tests due to relative movement between the electrode assembly and its outer packaging.

[0003] The space between the battery pack and the outer packaging of a battery product is filled with electrolyte. Therefore, the adhesive tape used as the outer packaging for the battery pack must meet electrolyte resistance requirements. Otherwise, the adhesive tape will lose effectiveness over extended storage and usage, making it difficult to effectively secure the battery pack, thereby reducing the stability and safety of the battery product.

[0004] With the development of science and technology, the requirements for battery products in various fields are becoming increasingly higher. The stability and safety of battery products are the performance indicators that the industry focuses on. How to further improve the stability and safety of battery products has significant technical and economic value. Summary of the Invention

[0005] In order to overcome the deficiencies and shortcomings of the prior art, an object of the present invention is to provide a battery having excellent structural stability and safety.

[0006] According to one aspect of the present invention, a battery is provided, comprising a battery cell and an outer packaging, wherein the battery cell and the outer packaging are connected by a battery protective double-sided tape, the battery protective double-sided tape comprising a surface adhesive layer and a substrate, both sides of the substrate being compounded with a layer of surface adhesive layer, and the raw materials for preparing the surface adhesive layer comprise, calculated by weight, 50 to 95 parts of a main resin, 1 to 50 parts of a tackifying resin, and 0 to 5 parts of a curing agent, wherein the main resin comprises a modified ethylene propylene diene monomer rubber having a grafted functional group, the functional group comprising a carboxyl group and / or a hydroxyl group, and the curing agent comprises at least one of an amino resin, a nitrogen pyridine, and an isocyanate.

[0007] The battery provided by this solution utilizes double-sided battery protective tape to securely bond the battery cell and outer packaging. This not only secures the components within the battery cell, but also reduces the possibility of relative displacement between the battery cell and outer packaging during battery injection and formation stages. By optimizing the raw material composition ratio of the surface adhesive layer of the battery protective tape and using modified EPDM rubber grafted with carboxyl and / or hydroxyl groups, the surface adhesive layer not only enhances its peeling force against metal and substrates but also its electrolyte resistance, maintaining good adhesion even when immersed in electrolyte, thereby improving the structural stability of the battery to which the battery protective tape is applied. It should be noted that EPDM (ethylene propylene diene monomer) is a copolymer of ethylene, propylene, and a small amount of non-conjugated diene. It is a type of EPDM. Because its main chain is composed of chemically stable saturated hydrocarbons and contains unsaturated double bonds only in the side chains, it has excellent aging resistance, including ozone resistance, heat resistance, and weather resistance. It has been widely used in automotive parts, building waterproofing materials, wire and cable sheathing, heat-resistant hoses, adhesive tapes, automotive seals, and other fields. However, EPDM has low surface energy, poor adhesion, and is prone to debonding and loss of adhesion, which limits its application in the adhesive tape field.

[0008] On the one hand, by adopting modified EPDM rubber grafted with carboxyl and / or hydroxyl groups and adjusting the ratio of the main resin to the tackifying resin in the surface glue layer, the bonding performance of the surface glue layer when immersed in the electrolyte can be improved, thereby reducing the probability of large displacement between the battery core and the outer packaging, preventing the battery core and the outer packaging from colliding and causing the battery structure to be destroyed, improving the stability of the electrode interface, and reducing the side reactions occurring inside the battery. Specifically, the carboxyl and / or hydroxyl groups can affect the electron distribution of the modified EPDM rubber, not only promoting the crosslinking degree of the surface glue layer formed by the main resin and the tackifying resin, but also the carboxyl and / or hydroxyl groups can increase the hydrogen bond content in the surface glue layer, thereby improving the density and permeation resistance of the surface glue layer, so that the surface glue layer that meets the above-mentioned formula requirements has good bonding performance after being soaked in the electrolyte, further improving the protection effect of the battery. On the other hand, the battery core is usually composed of a positive electrode, a separator, and a negative electrode, and the positive electrode current collector and / or the negative electrode current collector are generally exposed on the outermost side of the battery core. Batteries using this double-sided protective tape have excellent structural tightness. The tape secures the battery cell, preventing components such as the positive electrode, separator, and negative electrode from falling apart, and improving the tightness between the various components within the cell. Furthermore, batteries using this tape maintain a tight fit between the cell and the outer packaging, minimizing relative displacement between the cell and the outer packaging during stages such as injection and formation, further enhancing the structural stability of batteries using this tape.

[0009] Preferably, the grafting rate of the modified EPDM rubber in the main resin of the surface adhesive layer is 0.5-2%. By regulating the grafting rate of the modified EPDM rubber, the electrolyte resistance and adhesion properties of the surface adhesive layer can be improved simultaneously, so that the surface adhesive layer has good adhesion properties before and after the electrolyte soaking. This improves the structural stability of the battery during the injection, formation, and circulation stages, thereby improving the battery's electrochemical performance.

[0010] Preferably, the main resin also includes EPDM rubber. By using both unmodified EPDM rubber and modified EPDM rubber grafted with carboxyl and / or hydroxyl groups as the main resin, the peeling force of the surface adhesive layer on metal materials can be further increased, thereby improving the adhesion of the surface adhesive layer to the battery cell and / or outer packaging. This improves the structural stability and cycling stability of the battery.

[0011] Preferably, the mass ratio of EPDM rubber to modified EPDM rubber is 60-90:10-40. When the mass ratio of EPDM rubber to modified EPDM rubber in the main resin meets the above-mentioned range, the surface adhesive layer has excellent adhesion to the battery cell, outer packaging, and substrate, thereby enhancing the protective effect of the battery protective double-sided tape on the battery cell.

[0012] Preferably, the tackifying resin in the surface adhesive layer comprises a hydrogenated petroleum resin having a softening point of 100-150°C. By selecting a hydrogenated petroleum resin having a softening point of 100-150°C as the tackifying resin, the surface adhesive layer formed by cross-linking the tackifying resin with the main resin has excellent electrolyte resistance and adhesion, resulting in excellent battery stability and structural density. This prevents loosening of the battery's internal structure due to loss of adhesion in the surface adhesive layer, thereby reducing burrs and leakage in the battery cell.

[0013] Preferably, the substrate includes a first base film, a second base film, and a debonding adhesive layer disposed between the first base film and the second base film. By providing the debonding adhesive layer in the substrate, the drop resistance of the battery to which the battery protective double-sided tape is applied can be improved, wherein the debonding adhesive layer is sticky before being soaked in the electrolyte, and the adhesion of the debonding adhesive layer to the first base film and the second base film is significantly reduced when soaked in the electrolyte. Generally speaking, the toughness and strength of the battery outer packaging material are significantly higher than the toughness and strength of the bonding surface of the battery cell surface. Therefore, during the drop of the battery product, the pulling force exerted by the battery pole group outer packaging material on the conventional double-sided tape is greater than the pulling force exerted by the battery pole group bonding surface on the double-sided tape. The difference in the above pulling force can easily cause the double-sided tape to break or tear on the side adhered to the battery cell bonding surface. In more stringent drop tests, there is even a phenomenon of aluminum foil tearing, which has a negative impact on the drop resistance of the battery. By providing a releasable adhesive layer in the structure of the battery protection double-sided tape, the viscosity of the releasable adhesive layer decreases after the battery is formed, and a certain range of looseness occurs between the first base film and the second base film. Therefore, during the falling process of the battery, it is not easy for the side of the battery protection double-sided tape adhered to the bonding surface of the battery cell to collapse or tear due to the difference in pulling force, thereby reducing the probability of burrs generated by the current collector at the bonding surface of the battery cell due to collapse and tearing, further improving the battery's anti-drop performance, and preventing the battery from leaking, short circuiting and other safety risks due to falling.

[0014] In the composition of the surface adhesive layer used in this solution, by regulating the composition of the surface adhesive layer, industry professionals can flexibly make the surface adhesive layer exhibit pressure sensitivity or heat sensitivity according to actual needs.

[0015] Preferably, in at least one surface adhesive layer, the mass ratio of the main resin to the tackifying resin is 50-70:20-50. A surface adhesive layer meeting the above composition exhibits pressure sensitivity, meaning it exhibits excellent bonding properties both at room temperature and when immersed in an electrolyte, and maintains strong adhesion to metal materials and substrates.

[0016] When the surface adhesive layer is pressure-sensitive, preferably, the thickness of the surface adhesive layer is 2 to 4 μm.

[0017] Preferably, in at least one surface adhesive layer, the mass ratio of the main resin to the tackifying resin is 80 to 95:1 to 10. The surface adhesive layer meeting the above composition exhibits heat sensitivity, that is, the surface adhesive layer has low viscosity at room temperature, but exhibits high peeling force in a higher temperature environment.

[0018] When the surface adhesive layer is heat-sensitive, preferably, the thickness of the surface adhesive layer is 3 to 6 μm.

[0019] When the surface adhesive layer is heat-sensitive, preferably, calculated by weight, the raw materials used to prepare the surface adhesive layer include 80 to 95 parts of a main resin, 1 to 10 parts of a tackifying resin, and 0 to 2 parts of a curing agent.

[0020] Preferably, the surface adhesive layer further comprises a pigment, the pigment comprising at least one of phthalocyanine blue, titanium dioxide, inorganic cobalt blue, and inorganic cobalt green. Introducing the pigment into the raw materials for preparing the surface adhesive layer facilitates identification and positioning by the adhesive machine or staff during the adhesive application process.

[0021] Preferably, the first base film includes at least one of polyethylene terephthalate (PET), polyimide (PI), and polypropylene (PP).

[0022] Preferably, the second base film includes at least one of polyethylene terephthalate (PET), polyimide (PI), and polypropylene (PP).

[0023] Preferably, the thickness of the first base film is 1 to 6 μm.

[0024] Preferably, the second base film has a thickness of 1 to 6 μm.

[0025] Preferably, the thickness of the debonding layer is 1 to 3 μm.

[0026] Preferably, the thickness of the battery protection double-sided tape is 8 to 25 μm.

[0027] Preferably, the battery protection double-sided tape further includes a release layer, which is composited with at least one surface adhesive layer.

[0028] Preferably, the outer packaging includes at least one of an aluminum-plastic film, an aluminum shell, and a steel shell.

[0029] Preferably, the battery includes at least one of a lithium-ion battery, a sodium-ion battery, and a lead-acid battery.

[0030] Preferably, the battery cell includes a first surface and a second surface arranged back to back, and the battery protective double-sided tape is attached to the edge of the battery cell, with any continuous layer of surface adhesive layer adhered to the first surface and the second surface of the battery cell, so that the battery protective double-sided tape is U-shaped and wraps around the edge of the battery cell.

[0031] Preferably, the surface adhesive layer on one side of the substrate is a pressure-sensitive adhesive layer, and the surface adhesive layer on the other side of the substrate is a heat-sensitive adhesive layer. The battery protective double-sided adhesive tape is bonded to the battery cell using the pressure-sensitive adhesive layer, and bonded to the outer packaging using the heat-sensitive adhesive layer. When the outer packaging is made of a film-like material such as aluminum-plastic film, a heat-sensitive adhesive layer is typically used for bonding to reduce wrinkles in the aluminum-plastic film during bonding.

[0032] Preferably, the battery protective double-sided tape is provided on at least one set of opposite sides of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the interlayer structure of the battery protection double-sided tape used in the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of the battery protection double-sided tape attached to the first surface of the battery;

[0035] Figure 3 This is a schematic diagram of the structure of the battery protection double-sided tape attached to the second surface of the battery;

[0036] 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.

[0037] The meanings of the reference numerals are as follows:

[0038] 1. Battery cell; 11. First surface; 12. Second surface;

[0039] 2. Battery protection double-sided tape; 21. First surface adhesive layer; 22. First base film; 23. Debondable adhesive layer; 24. Second base film; 25. Second surface adhesive layer. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the drawings in the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides a battery protective double-sided adhesive tape and a battery.

[0043] (1) Battery protection double-sided tape

[0044] like Figure 1 As shown, the battery protective double-sided tape 2 includes a surface adhesive layer and a base material, with a surface adhesive layer laminated on each side of the base material. The base material includes a first base film 22, a second base film 24, and a releasable adhesive layer 23 disposed between the first and second base films 22, 24. The surface adhesive layer disposed on one side of the base material is referred to as the first surface adhesive layer 21, and the surface adhesive layer disposed on the other side of the base material is referred to as the second surface adhesive layer 25.

[0045] That is, the battery protective double-sided tape 2 includes a first surface adhesive layer 21, a first base film 22, a releasable adhesive layer 23, a second base film 24, and a second surface adhesive layer 25, which are arranged in sequence. The thickness of the first surface adhesive layer 21 is 3 μm, the thickness of the first base film 22 is 3 μm, the thickness of the releasable adhesive layer 23 is 2 μm, the thickness of the second base film 24 is 3 μm, and the thickness of the second surface adhesive layer 25 is 4 μm. Therefore, the thickness of the battery protective double-sided tape 2 is 15 μm.

[0046] Specifically, the first surface adhesive layer 21 is a pressure-sensitive adhesive layer formed by curing Glue A, which comprises 60 parts of a base resin, 35 parts of a tackifying resin, 2 parts of a curing agent, and 10 parts of a pigment. The base resin comprises EPDM rubber and modified EPDM rubber in a 90:10 mass ratio, with the modified EPDM rubber having a 1% carboxyl grafting rate. The tackifying resin is a hydrogenated petroleum resin with a softening point of 125±5°C, the curing agent is an amino resin, and the pigment is phthalocyanine blue.

[0047] The second surface adhesive layer 25 is a heat-sensitive adhesive layer formed by curing Glue B, which consists of 87 parts of a base resin, 6 parts of a tackifying resin, and 1 part of a curing agent. The base resin comprises EPDM rubber and modified EPDM rubber in a 60:40 mass ratio, with the modified EPDM rubber having a carboxyl grafting rate of 1%. The tackifying resin is a hydrogenated petroleum resin with a softening point of 105±5°C, and the curing agent is an amino resin.

[0048] The first base film 22 is made of polyethylene terephthalate (PET), and the second base film 24 is made of polyethylene terephthalate (PET).

[0049] The releasable adhesive layer 23 is formed by curing glue C, which includes 80 parts of ethylene vinyl acetate and 20 parts of hydrogenated rosin resin.

[0050] The preparation method of the battery protective double-sided tape 2 includes the following operations:

[0051] Using a coating process, glue A is coated on the surface of the release film to form a first surface adhesive layer 21; then the first base film is attached to the side of the first surface adhesive layer 21 away from the release film; glue C is coated on the surface of the first base film away from the first surface adhesive layer 21 to form a debonding adhesive layer 23 and then attached to the second base film 24; glue B is coated on the side of the second base film 24 away from the debonding adhesive layer 23 to form a second surface adhesive layer 25, thereby obtaining a battery protection double-sided tape 2.

[0052] The method for preparing carboxyl-modified EPDM rubber comprises the following steps:

[0053] 1.5 to 2.5 parts of carboxyl modified raw materials, 95 to 99 parts of ethylene propylene diene monomer rubber, a catalyst and a solvent were mixed according to parts by mass, and the mixture was reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl modified ternary rubber, wherein the grafting rate of the carboxyl group was 1%.

[0054] In other embodiments, the amount of the main resin, the type of tackifying resin, the softening point and amount of the main resin, and the mass ratio of EPDM to modified EPDM in glue A can be adjusted according to actual needs, and the addition of a curing agent and / or pigment can be omitted. Alternatively, the amount of the main resin, the type of tackifying resin, the softening point and amount of the main resin, and the mass ratio of EPDM to modified EPDM in glue B can be adjusted, and the addition of a curing agent can be omitted. Alternatively, the type and thickness of the first base film 22, the second base film 24, the releasable adhesive layer 23, and the thickness of the first surface adhesive layer 21 and / or the second surface adhesive layer 25 can be independently adjusted. Alternatively, the preparation method of the modified EPDM can be adjusted. This is provided that the normal use of the battery protective double-sided tape 2 is not affected.

[0055] (2)Battery

[0056] The battery comprises a battery core 1 and an outer package, wherein the battery core 1 and the outer package are connected via a battery protection double-sided adhesive tape 2. The outer package is made of aluminum-plastic film.

[0057] The battery preparation method includes the following operations:

[0058] The separator, negative electrode sheet, separator, and positive electrode sheet are stacked or wound to form a battery cell 1. The battery cell 1 is secured to the outside with the aforementioned double-sided battery protective tape 2, then packaged in an outer packaging. The battery cell is then dried, injected, and formed through steps such as chemical reaction. Furthermore, the electrolyte used includes a lithium salt (1 mol / L LiPF6) content of 12.5% ​​by mass and an organic solvent content of 87.5% by mass. The organic solvent comprises, by mass ratio, ethylene carbonate: propylene carbonate: diethyl carbonate: ethyl propionate = 30:10:30:30.

[0059] Specifically, the specific bonding method of the battery protection double-sided tape 2 is as follows: Figure 2 and Figure 3 As shown, the battery protective double-sided tape 2 is attached to the four edges of the battery cell 1. The battery protective double-sided tape 2 is attached to the battery cell 1 with a first surface adhesive layer 21 (pressure-sensitive adhesive layer); the battery protective double-sided tape 2 is attached to the outer packaging with a second surface adhesive layer 25 (heat-sensitive adhesive layer). The battery cell 1 includes a first surface 11 and a second surface 12 that are arranged back to back. The continuous first surface adhesive layer 21 is attached to the first surface 11 and the second surface 12 of the battery cell 1, so that the battery protective double-sided tape 2 wraps around the edge of the battery cell 1 in a U shape, as shown in FIG. Figure 4 shown.

[0060] Example 2

[0061] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. The difference between this example and Example 1 lies in that during the preparation of the first surface adhesive layer 21, the main resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a hydroxyl grafting rate of 1% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0062] The preparation method of the hydroxyl-modified EPDM rubber refers to the method provided in CN115386021A to prepare the carboxyl-modified ternary rubber, and the grafting rate of the carboxyl group is 1%.

[0063] Example 3

[0064] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the first surface adhesive layer 21, the main resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a carboxyl grafting rate of 0.3% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0065] The preparation method of carboxyl-modified EPDM rubber uses acrylic acid monomer as a carboxyl-modified raw material to prepare the carboxyl-modified ternary rubber, including the following operations:

[0066] 0.5 to 1 parts of carboxyl modified raw materials, 97 to 99 parts of ethylene propylene diene monomer rubber, a catalyst and a solvent were mixed according to parts by mass, and the mixture was reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl modified ternary rubber, wherein the grafting rate of the carboxyl group was 0.3%.

[0067] Example 4

[0068] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the first surface adhesive layer 21, the main resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a carboxyl grafting rate of 0.5% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0069] The preparation method of carboxyl-modified EPDM rubber uses acrylic acid monomer as a carboxyl-modified raw material to prepare the carboxyl-modified ternary rubber, including the following operations:

[0070] Calculated by weight, 1 to 2 parts of a carboxyl-modified raw material, 97 to 99 parts of ethylene propylene diene monomer rubber, a catalyst, and a solvent are mixed, and the mixture is reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl-modified ternary rubber, wherein the grafting rate of the carboxyl group is 0.5%.

[0071] Example 5

[0072] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the first surface adhesive layer 21, the main resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a carboxyl grafting rate of 2% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0073] The preparation method of carboxyl-modified EPDM rubber uses acrylic acid monomer as a carboxyl-modified raw material to prepare the carboxyl-modified ternary rubber, including the following operations:

[0074] Calculated by weight, 2.5 to 4.5 parts of a carboxyl-modified raw material, 95 to 99 parts of ethylene propylene diene monomer rubber, a catalyst, and a solvent are mixed, and the mixture is reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl-modified ternary rubber, wherein the grafting rate of the carboxyl group is 2%.

[0075] Example 6

[0076] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the first surface adhesive layer 21, the main resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a carboxyl grafting rate of 2.5% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0077] The preparation method of carboxyl-modified EPDM rubber uses acrylic acid monomer as a carboxyl-modified raw material to prepare the carboxyl-modified ternary rubber, including the following operations:

[0078] 3 to 5 parts of a carboxyl-modified raw material, 95 to 99 parts of ethylene propylene diene monomer rubber, a catalyst and a solvent were mixed according to parts by mass, and reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl-modified ternary rubber, wherein the grafting rate of the carboxyl group was 2.5%.

[0079] Example 7

[0080] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. The difference between this example and Example 1 is that during the preparation of the first surface adhesive layer 21, the tackifying resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, the tackifying resin in Example 1 is replaced with an equal mass of hydrogenated rosin resin having a softening point of 105±5°C. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0081] Example 8

[0082] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided adhesive tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the first surface adhesive layer 21, the proportions of the main resin and the tackifying resin in the glue A used to prepare the first surface adhesive layer 21 are adjusted. Specifically, the main resin is 50 parts and the tackifying resin is 20 parts. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0083] Example 9

[0084] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided adhesive tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the first surface adhesive layer 21, the proportions of the main resin and the tackifying resin in the glue A used to prepare the first surface adhesive layer 21 are adjusted. Specifically, the main resin is 70 parts and the tackifying resin is 50 parts. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0085] Comparative Example 1

[0086] This comparative example uses the preparation method provided in Example 1 to prepare a double-sided adhesive tape and a battery. This comparative example differs from Example 1 in that, during the preparation of first surface adhesive layer 21, the main resin in glue A used to prepare first surface adhesive layer 21 is adjusted. Specifically, unmodified EPDM rubber of equal mass is used in place of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods remain strictly consistent with those in Example 1.

[0087] Comparative Example 2

[0088] This comparative example uses the preparation method provided in Example 1 to prepare a double-sided adhesive tape and a battery. This comparative example differs from Example 1 in that during the preparation of the first surface adhesive layer 21, the main resin in the glue A used to prepare the first surface adhesive layer 21 is adjusted. Specifically, an equal mass of styrene-isoprene-styrene block copolymer (SIS) is used instead of the modified EPDM rubber in Example 1. The grafting rate of the hydroxyl-modified SIS is 1%. The remaining raw material ratios and preparation methods remain identical to those in Example 1.

[0089] Test Example 1

[0090] Test Subjects: Single-sided tapes were prepared using Glue A provided in Examples 1-9 and Glue A provided in Comparative Examples 1-2. Specifically, the single-sided tapes included a first surface adhesive layer and a first base film laminated in sequence. The first surface adhesive layer was a pressure-sensitive adhesive layer formed from Glue A provided in Examples 1-9 and Glue A provided in Comparative Examples 1-2, respectively. These single-sided adhesive layers served as test subjects.

[0091] Test items and test methods:

[0092] (1) Peel force test before immersion in electrolyte:

[0093] S1. In an environment of 23±2°C and 50±5% RH, apply copper foil to the pressure-sensitive adhesive surface of the test object.

[0094] S2. Then, attach 5000NS tape and a steel plate to the side of the copper foil facing away from the test object. Attach 5000NS tape to the side of the test object facing away from the copper foil as a traction tape.

[0095] S3. Then use a Kejian tensile tester to clamp the steel plate and the traction tape respectively to perform a peeling force test. The peeling speed is 50mm / min and the peeling angle is 180°. Record the peeling force data and take the average value of a 60mm section after the reading stabilizes (if a severe jagged curve appears, take the average value of the maximum value of the curve every 10mm after stabilization). The judgment standard is the average value of 5 parallel samples.

[0096] (2) Peel strength test after immersion in electrolyte:

[0097] S1. In an environment of 23±2°C and 50±5% RH, apply copper foil to the pressure-sensitive adhesive surface of the test object.

[0098] S2. The composite structure composed of the copper foil and the test object is then immersed in an electrolyte at a temperature of 85±1°C for 4 hours. The components of the electrolyte used are as follows: the mass content of lithium salt (1 mol / L LiPF6) is 12.5%, and the mass content of the organic solvent is 87.5%: calculated by mass ratio, in the organic solvent, ethylene carbonate: propylene carbonate: diethyl carbonate: ethyl propionate = 30:10:30:30.

[0099] S3. After the immersion is completed, the composite structure is removed from the electrolyte.

[0100] S4. Return the test environment to 23±2°C and 50±5% RH. Apply 5000NS tape and a steel plate to the side of the copper foil facing away from the test object. Apply 5000NS tape as a traction tape to the side of the test object facing away from the copper foil.

[0101] S5. Then use a Kejian tensile tester to clamp the steel plate and the traction tape respectively to perform a peeling force test. The peeling speed is 50mm / min and the peeling angle is 180°. Record the peeling force data and take the average value of a 60mm section after the reading stabilizes (if a severe jagged curve appears, take the average value of the maximum value of the curve every 10mm after stabilization). The judgment standard is the average value of 5 parallel samples.

[0102] Test results: as shown in Table 1.

[0103] Table 1. Peel force test results of pressure-sensitive adhesive layer

[0104]

[0105] Result analysis:

[0106] Comparing the peel force test performance of Examples 1-9 with that of Comparative Examples 1-2 in Table 1, it can be found that the pressure-sensitive adhesive layers provided in Examples 1-9 have superior adhesive properties and electrolyte resistance compared to the pressure-sensitive adhesive layers provided in Comparative Examples 1-2, as evidenced by the peel force of the pressure-sensitive adhesive layers provided in Examples 1-9 after soaking in electrolyte being ≥0.05 N / mm. The pressure-sensitive adhesive layer of Comparative Example 1 uses unmodified EPDM rubber as the main resin, while the pressure-sensitive adhesive layer of Comparative Example 2 uses both SIS and unmodified EPDM rubber as the main resin. However, the pressure-sensitive adhesive layers of Comparative Examples 1-2 both exhibit lower peel forces after soaking in electrolyte. This demonstrates that when modified EPDM rubber containing hydroxyl and / or carboxyl groups is introduced into the main resin, the resulting pressure-sensitive adhesive layer exhibits both excellent adhesive properties and electrolyte resistance.

[0107] Comparing the pressure-sensitive adhesive layers provided in Examples 1 and 2, it was found that the tape of Example 1 exhibited higher electrolyte resistance than the tape of Example 2, as evidenced by superior peel strength after soaking in electrolyte. This demonstrates that, compared to hydroxyl-modified EPDM rubber, the surface adhesive layer using carboxyl-modified EPDM rubber as the subject resin exhibited superior electrolyte resistance.

[0108] Comparing the adhesive tapes provided in Example 1 with those provided in Examples 3-6, it can be found that as the grafting rate of the modified EPDM rubber increases, the peeling force of the surface adhesive layer before soaking in the electrolyte also increases, but the peeling force of the surface adhesive layer after soaking in the electrolyte shows a trend of first increasing and then decreasing. Compared with the surface adhesive layers provided in Examples 3 and 6, the peeling force of the surface adhesive layers provided in Examples 1 and Examples 4-5 before and after soaking in the electrolyte is greater than 0.08 N / mm. This indicates that when the grafting rate of the modified EPDM rubber is 0.5-2%, the surface adhesive layer has a high peeling force both before and after soaking in the electrolyte, and in particular, the surface adhesive layer has excellent bonding properties after soaking in the electrolyte.

[0109] By comparing the adhesive tapes provided in Example 1 with those provided in Example 7, it can be found that although the peeling forces of the surface adhesive layers provided in Example 1 and Example 7 before immersion in the electrolyte are similar, the peeling force of the surface adhesive layer provided in Example 1 is higher after immersion in the electrolyte, reflecting better electrolyte resistance. That is to say, when the softening point is 100-150°C, the use of hydrogenated petroleum resin as the tackifying resin can make the surface adhesive layer formed by cross-linking the tackifying resin and the main resin have excellent electrolyte resistance and bonding properties.

[0110] Example 10

[0111] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the second surface adhesive layer 25, the main resin in the glue B used to prepare the second surface adhesive layer 25 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a carboxyl grafting rate of 0.5% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods remain strictly consistent with those in Example 1.

[0112] The preparation method of carboxyl-modified EPDM rubber uses acrylic acid monomer as a carboxyl-modified raw material to prepare the carboxyl-modified ternary rubber, including the following operations:

[0113] Calculated by weight, 1 to 2 parts of a carboxyl-modified raw material, 97 to 99 parts of ethylene propylene diene monomer rubber, a catalyst, and a solvent are mixed, and the mixture is reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl-modified ternary rubber, wherein the grafting rate of the carboxyl group is 0.5%.

[0114] Example 11

[0115] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the second surface adhesive layer 25, the main resin in the glue B used to prepare the second surface adhesive layer 25 is adjusted. Specifically, the modified EPDM rubber of the same mass and having a carboxyl grafting rate of 2% is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods remain strictly consistent with those in Example 1.

[0116] The preparation method of carboxyl-modified EPDM rubber uses acrylic acid monomer as a carboxyl-modified raw material to prepare the carboxyl-modified ternary rubber, including the following operations:

[0117] Calculated by weight, 2.5 to 4.5 parts of a carboxyl-modified raw material, 95 to 99 parts of ethylene propylene diene monomer rubber, a catalyst, and a solvent are mixed, and the mixture is reacted at a reaction temperature of 80±5° C. under a nitrogen environment to prepare a carboxyl-modified ternary rubber, wherein the grafting rate of the carboxyl group is 2%.

[0118] Example 12

[0119] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided adhesive tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the second surface adhesive layer 25, the proportions of the main resin and the tackifying resin in the glue A used to prepare the second surface adhesive layer 25 are adjusted. Specifically, the main resin is 80 parts and the tackifying resin is 3 parts. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0120] Example 13

[0121] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided adhesive tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the second surface adhesive layer 25, the proportions of the main resin and the tackifying resin in the glue A used to prepare the second surface adhesive layer 25 are adjusted. Specifically, the main resin is 95 parts and the tackifying resin is 10 parts. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0122] Comparative Example 3

[0123] This comparative example uses the preparation method provided in Example 1 to prepare a double-sided adhesive tape and a battery. This comparative example differs from Example 1 in that, during the preparation of the second surface adhesive layer 25, the main resin in the glue A used to prepare the second surface adhesive layer 25 is adjusted. Specifically, an equal mass of unmodified EPDM rubber is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods remain strictly consistent with those in Example 1.

[0124] Comparative Example 4

[0125] This comparative example uses the preparation method provided in Example 1 to prepare a double-sided adhesive tape and a battery. This comparative example differs from Example 1 in that, during the preparation of the second surface adhesive layer 25, the main resin in the glue A used to prepare the second surface adhesive layer 25 is adjusted. Specifically, an equal mass of styrene-isoprene-styrene block copolymer (SIS) is used instead of the modified EPDM rubber in Example 1. The remaining raw material ratios and preparation methods remain strictly consistent with those in Example 1.

[0126] Test Example 2

[0127] Test subjects: Single-sided tapes were prepared using the glue B provided in Example 1, Examples 10-13, and the glue B provided in Comparative Examples 3-4. Specifically, the single-sided tapes included a second surface adhesive layer and a second base film, which were laminated in sequence. The second surface adhesive layer was a heat-sensitive adhesive layer, which was formed using the glue B provided in Example 1, Examples 10-13, and the glue B provided in Comparative Examples 3-4, respectively. The above single-sided adhesive layers were used as test subjects.

[0128] Test items and test methods:

[0129] (1) Peel force test before hot pressing:

[0130] S1. At 23±2°C and 50±5% RH, apply 5000NS tape as a traction tape to the side of the second basement membrane of the test object facing away from the heat-sensitive adhesive layer.

[0131] S2. Next, lay the test object with the traction tape attached flat on a steel plate, with the thermal adhesive facing the steel plate. Use a Kejian tensile tester to clamp the steel plate and the traction tape, respectively, and perform a peel force test. A peel force of ≤0.05 N / mm is considered acceptable.

[0132] (2) Peel force test after hot pressing and before immersion in electrolyte:

[0133] S1. Lay the test object flat on a steel plate with the heat-sensitive adhesive side facing the steel plate at 23±2°C and 50±5% RH. Attach copper foil to the pressure-sensitive adhesive side of the test object. Then, hot-press the composite structure consisting of the copper foil, test object, and steel plate at a temperature of 85°C, a pressure of 600 kg, and a time of 30 minutes.

[0134] S2. Return the test environment to 23±2°C and 50±5% RH, and then apply 5000NS tape as a traction tape to the side of the second basement membrane of the test object facing away from the heat-sensitive adhesive layer.

[0135] S3. Then use a Kejian tensile tester to clamp the steel plate and the traction tape respectively to perform a peeling force test. The peeling speed is 50mm / min and the peeling angle is 180°. Record the peeling force data and take the average value of a 60mm section after the reading stabilizes (if a severe jagged curve appears, take the average value of the maximum value of the curve every 10mm after stabilization). The judgment standard is the average value of 5 parallel samples.

[0136] (3) Peel strength test after hot pressing and immersion in electrolyte:

[0137] S1. Lay the test object flat on a steel plate with the heat-sensitive adhesive side facing the steel plate at 23±2°C and 50±5% RH. Attach copper foil to the pressure-sensitive adhesive side of the test object. Then, hot-press the composite structure consisting of the copper foil, test object, and steel plate at a temperature of 85°C, a pressure of 600 kg, and a time of 30 minutes.

[0138] S2. The composite structure is then immersed in an electrolyte at a temperature of 85±1°C for 4 hours. The components of the electrolyte used are as follows: the mass content of lithium salt (1 mol / L LiPF6) is 12.5%, and the mass content of the organic solvent is 87.5%: calculated by mass ratio, ethylene carbonate: propylene carbonate: diethyl carbonate: ethyl propionate = 30:10:30:30 in the organic solvent.

[0139] S3. After the immersion is completed, the composite structure is removed from the electrolyte.

[0140] S4. Return the test environment to 23±2°C and 50±5% RH, and then apply 5000NS tape as a traction tape to the side of the second basement membrane of the test object facing away from the heat-sensitive adhesive layer.

[0141] S5. Then use a Kejian tensile tester to clamp the steel plate and the traction tape respectively to perform a peeling force test. The peeling speed is 50mm / min and the peeling angle is 180°. Record the peeling force data and take the average value of a 60mm section after the reading stabilizes (if a severe jagged curve appears, take the average value of the maximum value of the curve every 10mm after stabilization). The judgment standard is the average value of 5 parallel samples.

[0142] Test results: as shown in Table 2.

[0143] Table 2. Peel force test results of thermal adhesive layer

[0144]

[0145]

[0146] Result analysis:

[0147] Comparing the peel force test performance of Example 1 and Examples 10 to 13 with Comparative Examples 3 to 4 in Table 1, it can be found that compared with the heat-sensitive adhesive layers provided in Comparative Examples 3 to 4, the heat-sensitive adhesive layers provided in Example 1 and Examples 10 to 13 have excellent adhesion performance and electrolyte resistance after hot pressing, which is reflected in that the peel force of the heat-sensitive adhesive layers provided in Example 1 and Examples 10 to 13 after hot pressing and before soaking in electrolyte is ≥0.15 N / mm, and the peel force after hot pressing and after soaking in electrolyte is ≥0.15 N / mm. Among them, the thermal adhesive layer of Comparative Example 1 uses unmodified EPDM rubber as the main resin, and the thermal adhesive layer of Comparative Example 2 uses styrene-isoprene-styrene block copolymer (SIS) and unmodified EPDM rubber as the main resin. However, the thermal adhesive layers of Comparative Examples 1 and 2 all show low peeling force after being immersed in electrolyte. This shows that when modified EPDM rubber with hydroxyl and / or carboxyl groups is introduced into the main resin, the obtained thermal adhesive layer has both better bonding performance and electrolyte resistance.

[0148] Comparing the adhesive tapes provided in Example 1 with those provided in Examples 10-11, it can be found that as the grafting rate of the modified EPDM rubber increases, the peeling force of the surface adhesive layer before soaking in the electrolyte also increases, but the peeling force of the surface adhesive layer after soaking in the electrolyte shows a trend of first increasing and then decreasing. The peeling force of the surface adhesive layers provided in Examples 1 and 10-11 before and after soaking in the electrolyte is all within the excellent range, indicating that when the grafting rate of the modified EPDM rubber is 0.5-2%, the peeling force of the surface adhesive layer before hot pressing is low, and good adhesive properties are maintained after hot pressing, before soaking in the electrolyte, and after hot pressing and then soaking in the electrolyte.

[0149] Furthermore, by comparing the peel force test results of the pressure-sensitive adhesive layer shown in Table 1 with the peel force test results of the heat-sensitive adhesive layer shown in Table 2, it can be found that when the mass ratio of the main resin to the tackifying resin in the surface adhesive layer is 50-70:20-50, the surface adhesive layer exhibits pressure sensitivity. When the mass ratio of the main resin to the tackifying resin in the surface adhesive layer is 80-95:1-10, the surface adhesive layer exhibits heat sensitivity.

[0150] Example 15

[0151] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the battery protective double-sided tape, polyethylene terephthalate (PET) with a thickness of 4 μm is used as the substrate, replacing the substrate (first base film 22, releasable adhesive layer, and second base film 24) in Example 1. Specifically, the battery protective double-sided tape includes a first surface adhesive layer 21, a substrate, and a second surface adhesive layer 25, which are laminated in sequence. The remaining raw material ratios and preparation methods remain strictly consistent with those in Example 1.

[0152] Test Example 3

[0153] Test objects: the batteries provided in Examples 1 to 15, and the batteries provided in Comparative Examples 1 to 4.

[0154] Test items and test methods:

[0155] (1) 1.8m vertical drop test: Place the six sides and four corners of the lithium battery facing the ground, and then drop the lithium battery vertically from a height of 1.8m. After the drop test, test the lithium battery voltage. If the voltage change is less than 60mV, it is considered a pass, otherwise it fails. If the battery smokes or catches fire, it is considered a fail.

[0156] The drop test pass rate is calculated according to formula (1).

[0157]

[0158] Test results: as shown in Table 3

[0159] Table 3. Battery drop test results

[0160]

[0161]

[0162] Result analysis:

[0163] It can be seen from the performance results of Examples 1 to 15 and Comparative Examples 1 to 4 that the battery using the battery protective double-sided tape has a good fixing effect on the components in the battery cell and reduces the possibility of relative displacement between the battery cell and the outer packaging, which is reflected in the battery passing the drop test.

[0164] Furthermore, by comparing the performance results of Example 1 with those of Example 15 in Table 3, it can be found that by providing a debonding adhesive layer in the substrate of the battery protection double-sided tape, the drop resistance of the battery to which the battery protection double-sided tape is applied can be improved.

[0165] Example 16

[0166] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the battery protective double-sided tape, glue B is used instead of glue A in Example 1, resulting in a first surface adhesive layer 21 having a thickness of 3 μm. The remaining raw material ratios and preparation method are strictly consistent with those in Example 1.

[0167] Example 17

[0168] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that, during the preparation of the battery protective double-sided tape, glue A is used instead of glue B in Example 1, resulting in a second surface adhesive layer 25 having a thickness of 4 μm. The remaining raw material ratios and preparation method remain strictly consistent with those in Example 1.

[0169] Example 18

[0170] This example uses the preparation method provided in Example 1 to prepare a battery protective double-sided tape 2 and a battery. This example differs from Example 1 in that a steel shell is used as the outer packaging during the battery preparation process. The remaining raw material ratios and preparation method are strictly consistent with those in Example 1.

[0171] 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 the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A battery, characterized in that: The battery cell and the outer packaging are connected by a battery protective double-sided tape, the battery protective double-sided tape comprises a surface adhesive layer and a base material, both sides of the base material are respectively compounded with a layer of the surface adhesive layer, and the base material comprises a first base film, a second base film and a releasable adhesive layer disposed between the first base film and the second base film; Calculated by mass, the raw materials used to prepare the surface adhesive layer include 50 to 95 parts of a main resin, 1 to 50 parts of a tackifying resin, and 0 to 5 parts of a curing agent. The main resin includes EPDM rubber and modified EPDM rubber with grafted functional groups, the functional groups include carboxyl groups and / or hydroxyl groups, and the curing agent includes at least one of an amino resin, a nitrogen pyridine, and an isocyanate. The mass ratio of the EPDM rubber to the modified EPDM rubber is 60 to 90:10 to 40.

2. The battery according to claim 1, wherein: In the surface rubber layer, the grafting rate of the modified EPDM rubber in the main resin is 0.5-2%.

3. The battery according to claim 1, wherein: In the surface adhesive layer, the tackifying resin includes a hydrogenated petroleum resin having a softening point of 100-150°C.

4. The battery according to claim 1, wherein: In at least one layer of the surface adhesive layer, the mass ratio of the main resin to the tackifying resin is 50-70:20-50.

5. The battery according to claim 1, wherein: In at least one layer of the surface adhesive layer, the mass ratio of the main resin to the tackifying resin is 80-95:1-10.

6. The battery according to claim 1, wherein: The thickness of the battery protection double-sided tape is 8-25 μm.

7. The battery according to any one of claims 1 to 6, characterized in that: The battery cell includes a first surface and a second surface arranged back to back, and the battery protective double-sided tape is attached to the edge of the battery cell. Any layer of the surface adhesive layer is simultaneously attached to the first surface and the second surface, so that the battery protective double-sided tape is U-shaped and wraps around the edge of the battery cell.

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