Buffer rubber frame, preparation method thereof and square shell battery cell

Abstract

The invention provides a buffer rubber frame, a preparation method thereof and a square-shell battery cell. The buffering rubber frame is of a single-layer structure or a multi-layer structure. When the buffering rubber frame is of a single-layer structure, the hardness of the buffering rubber frame continuously changes in the thickness direction. When the buffering rubber frame is of a multi-layer structure, the buffering rubber frame comprises a first rubber frame layer, a second rubber frame layer and a third rubber frame layer which are arranged in a stacked mode, and the hardness of the first rubber frame layer is smaller than the hardness of the second rubber frame layer and larger than the hardness of the third rubber frame layer. The single-layer buffer rubber frame with the hardness continuously changing in the thickness direction is designed, or the rubber frame layers with different hardness are combined to construct the buffer rubber frame with a multi-layer structure, so that the overall mechanical property of the buffer rubber frame is accurately regulated and controlled, the stress distribution in the dynamic compression process of the square-shell battery cell is accurately controlled, and the stability of the square-shell battery cell is improved. The complex mechanical requirement of dynamic expansion of the battery cell is met, and the structural safety and the functional stability of the battery pack are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials, and particularly relates to a buffer rubber frame, a preparation method thereof, and a square shell battery cell. Background Art

[0002] In square shell battery cells, the buffer rubber frames used are mostly made of a single material (such as EPDM, silica gel, etc.). Since the square shell battery cell expands and contracts during charge and discharge, which will cause repeated compression on the rubber frame, the traditional buffer rubber frame with a fixed stress-strain curve cannot meet the complex mechanical requirements of the dynamic expansion of the battery cell. Therefore, it is difficult to meet the customer's requirements for a specific stress-strain curve (i.e., it needs to be within the corresponding stress range under different strains), resulting in limited structural safety and functional stability of the battery pack.

[0003] Although in the prior art, some solutions attempt to optimize the performance of the buffer rubber frame by changing the cross-sectional shape or adding fillers, it is easy to cause poor material uniformity, significant performance attenuation after long-term compression, and lack of precise control of the stress distribution during dynamic compression, affecting the overall safety of the battery pack. In addition, the adjustment range is limited and the process is complex.

[0004] Therefore, how to precisely control the stress distribution during the dynamic compression of the square shell battery cell to meet the complex mechanical requirements of the dynamic expansion of the battery cell, so as to improve the structural safety and functional stability of the battery pack, is a technical problem to be solved urgently. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a buffer rubber frame, a preparation method thereof, and a square shell battery cell. The present invention designs a single-layer buffer rubber frame with a continuously changing hardness along the thickness direction, or constructs a multi-layer structure buffer rubber frame by combining rubber frame layers with different hardnesses, so as to precisely regulate the overall mechanical properties of the buffer rubber frame, thereby precisely controlling the stress distribution during the dynamic compression of the square shell battery cell, meeting the complex mechanical requirements of the dynamic expansion of the battery cell, and being beneficial to improving the structural safety and functional stability of the battery pack.

[0006] To achieve the purpose of the present invention, the following technical solutions are adopted:

[0007] In the first aspect, the present invention provides a buffer rubber frame, and the buffer rubber frame is a single-layer structure or a multi-layer structure;

[0008] Wherein, when the buffer rubber frame is a single-layer structure, the hardness of the buffer rubber frame continuously changes along the thickness direction; when the buffer rubber frame is a multi-layer structure, it includes a first rubber frame layer, a second rubber frame layer, and a third rubber frame layer arranged in a stacked manner, and the hardness of the first rubber frame layer < the hardness of the second rubber frame layer > the hardness of the third rubber frame layer.

[0009] The buffer rubber frame structure provided by the present invention precisely regulates the mechanical properties of the overall buffer rubber frame, meets the customer's requirements for a specific stress-strain curve of the buffer rubber frame, thereby precisely controlling the stress distribution during the dynamic compression of the square shell battery cell, meeting the complex mechanical requirements of the dynamic expansion of the battery cell, and being beneficial to improving the structural safety and functional stability of the battery pack.

[0010] The present invention provides a single-layer buffer rubber frame with a continuously varying hardness along the thickness direction, which can not only meet the customer's requirements for a specific stress-strain curve of the buffer rubber frame, but also simplifies the structure and has a lower cost.

[0011] The present invention provides a multi-layer structure buffer rubber frame constructed by rubber frame layers with different hardnesses. The multi-layer structure disperses stress concentration, can delay material fatigue, and improve the service life of the buffer rubber frame.

[0012] The buffer rubber frame structure provided by the present invention is applicable to square shell battery cells with different sizes and expansion rates, greatly improving the flexibility of battery pack design.

[0013] Preferably, when the buffer rubber frame is of a single-layer structure, the rubber material of the buffer rubber frame includes foamed rubber.

[0014] It should be noted that foamed rubber is a rubber material with a porous structure, which is made by introducing gas into a rubber matrix (exemplarily, such as styrene-butadiene rubber (SBR), chloroprene rubber (CR), or ethylene propylene diene monomer rubber (EPDM), etc.) to form a large number of tiny air bubbles.

[0015] Preferably, when the buffer rubber frame is of a single-layer structure, the continuous change mode of the hardness of the buffer rubber frame along the thickness direction is as follows:

[0016] The hardness of the buffer rubber frame continuously decreases from the middle of the layer thickness to both sides of the layer thickness from 60A to 40A. Here, "A" refers to the A-type hardness in the Shore hardness.

[0017] By adopting the above hardness change mode, the present invention can precisely regulate the mechanical properties of the buffer rubber frame and meet the customer's requirements for a specific stress-strain curve of the buffer rubber frame.

[0018] Preferably, the buffer rubber frame is doped with a modification material, and the modification material includes any one or a combination of at least two of carbon black materials, silicate materials, fiber reinforcements, toughening modifiers, or functional additives.

[0019] In the present invention, by doping a modified material in the buffer rubber frame, effects such as improving tensile strength, wear resistance, balancing elasticity and strength, increasing stiffness, heat resistance, enhancing gas barrier properties, damping performance, tear resistance, fatigue resistance, increasing compression modulus, improving low-temperature toughness, improving resilience, enhancing impact strength, delaying thermal-oxidative aging, surface ozone protection, and improving flame retardancy (UL94 V-0 grade) can be achieved.

[0020] It should be noted that if the modified material is nanoscale, pre-dispersion (such as ultrasonic treatment) is required, and the fiber surface of the fiber reinforcement needs to be treated with a surface coupling agent.

[0021] Preferably, the silicate material includes any one or a combination of at least two of talcum powder, silica, or organically modified montmorillonite.

[0022] Preferably, the fiber reinforcement includes chopped aramid fiber and / or glass fiber.

[0023] Preferably, the toughening modifier includes any one or a combination of at least two of high-aromatic oil, polybutene rubber, thermoplastic elastomer, or core-shell acrylate.

[0024] Preferably, the functional additive includes any one or a combination of at least two of antistatic agents (such as carbon nanotubes, etc.), anti-aging agents, microcrystalline wax, or flame retardants.

[0025] Preferably, the doping fraction of the carbon black material in the buffer rubber frame is 10-25 wt%, for example, it can be 10 wt%, 15 wt%, 20 wt%, or 25 wt%, etc. Exemplarily, when the carbon black material is high-abrasion carbon black (such as N330), the doping fraction is 15-25 wt%, which can effectively improve tensile strength and wear resistance; when the carbon black material is general carbon black (such as N550), the doping fraction is 10-20 wt%, which can effectively balance elasticity and strength. If the doping is excessive, the elasticity and fatigue life will be reduced.

[0026] Preferably, the doping fraction of the silicate material in the buffer rubber frame is 1-18 wt%, for example, it can be 1 wt%, 5 wt%, 10 wt%, 15 wt%, or 18 wt%, etc. Exemplarily, if the silicate material is talcum powder (micron scale), the doping ratio is 10-18 wt%, which can increase stiffness and heat resistance; if the silicate material is organically modified montmorillonite (nanoscale), the doping fraction is 1-3 wt%, which can enhance gas barrier properties and damping performance, and it should be noted that nanoscale materials must be surface-treated to avoid agglomeration. If the doping fraction exceeds 3 wt%, it may increase viscosity and affect the processing effect.

[0027] Preferably, the doping fraction of the fiber reinforcement in the buffer rubber frame is 2-8 wt%, for example, it can be 2 wt%, 4 wt%, 6 wt%, 8 wt%, etc. Exemplarily, when the fiber reinforcement is short aramid fiber, the doping fraction is 3-8 wt%, which helps to improve the tear resistance and fatigue resistance; when the fiber reinforcement is glass fiber, the doping fraction is 2-6%, which helps to improve the compression modulus. If the doping fraction of the fiber reinforcement in the buffer rubber frame is greater than 8 wt%, it may lead to too strong anisotropy.

[0028] Preferably, the doping fraction of the toughening modifier in the buffer rubber frame is 2-15 wt%, for example, it can be 2 wt%, 5 wt%, 10 wt%, 15 wt%, etc. Exemplarily, when the toughening modifier is polybutene rubber (BR), the doping fraction is 8-15 wt%, which helps to improve the low-temperature toughness; when the toughening modifier is thermoplastic elastomer (SEBS), the doping fraction is 5-10 wt%, which helps to improve the resilience; when the toughening modifier is core-shell acrylate, the doping fraction is 2-5 wt%, which helps to enhance the impact strength.

[0029] Preferably, the doping fraction of the functional additive in the buffer rubber frame is 0.5-25 wt%, for example, it can be 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, etc. Exemplarily, when the functional additive is an anti-aging agent (such as RD + 4020, etc.), the doping fraction is 1-2%, which helps to delay the thermal-oxidative aging; when the functional additive is microcrystalline wax, the doping fraction is 0.5-1.5 wt%, which helps to prevent ozone on the surface; when the functional additive is a flame retardant (such as aluminum hydroxide, etc.), the doping fraction is 15-25 wt%, which helps to enhance the flame retardancy.

[0030] Exemplarily, for the buffer rubber frame with a multi-layer structure (including the first rubber frame layer, the second rubber frame layer and the third rubber frame layer arranged in layers), the modified materials doped in the first rubber frame layer can include N330 carbon black (20 wt%), white carbon black (i.e., amorphous silica in white powder or granular form) 8 wt% and anti-aging agent (RD + 4020) 1.5 wt%, which is beneficial to improving the tensile strength and wear resistance; the modified materials doped in the second rubber frame layer can include talcum powder 15 wt% and high-aromatic oil 12 wt%, which have high damping characteristics; the modified materials doped in the third rubber frame layer can include thermoplastic elastomer 8 wt% and antistatic agent 1 wt%.

[0031] Preferably, when the buffer rubber frame is a single-layer structure, the total proportion of the modified materials in the buffer rubber frame ≤ 50 wt%, for example, it can be 50 wt%, 40 wt%, 30 wt%, 20 wt%, 10 wt%, etc.

[0032] Preferably, when the buffer rubber frame is a multi-layer structure, the total proportion of the modified material in each rubber frame layer is independently ≤ 50 wt%, for example, it can be 50 wt%, 40 wt%, 30 wt%, 20 wt% or 10 wt%, etc.

[0033] Preferably, the rubber material of the first rubber frame layer includes any one or a combination of at least two of soft silicone rubber, natural rubber (NR), polyurethane elastomer (TPU), styrene-butadiene rubber (SBR), or cis-butadiene rubber (BR).

[0034] In the present invention, the first rubber frame layer has a lower hardness and is responsible for initial compression buffering.

[0035] Preferably, the material of the second rubber frame layer includes any one or a combination of at least two of fluororubber (FKM), hydrogenated nitrile rubber (HNBR), chlorinated ether rubber (ECO), or acrylate rubber (ACM).

[0036] It should be noted that fluororubber refers to a synthetic high molecular elastomer in which fluorine atoms are contained in the main chain or side chain carbon atoms.

[0037] In the present invention, the second rubber frame layer has the highest hardness, can limit the final compression amount, and ensure the structural stability.

[0038] Preferably, the material of the third rubber frame layer includes any one or a combination of at least two of ethylene propylene diene monomer rubber (EPDM), butyl rubber (IIR), chloroprene rubber (CR), or ethylene-vinyl acetate rubber (EVA).

[0039] In the present invention, the third rubber frame layer has a moderate hardness, is stronger than the first rubber frame layer, can provide medium support force, and prevent excessive deformation.

[0040] Preferably, the thickness ratio of the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer is (0.3 - 2.1):(0.3 - 2.1):(0.6 - 1), where the thickness selection range of the first rubber frame layer "0.3 - 2.1" can be, for example, 0.3, 0.5, 0.7, 0.9, or 2.1, etc., the thickness selection range of the second rubber frame layer "0.3 - 2.1" can be, for example, 0.3, 0.5, 0.7, 0.9, or 2.1, etc., and the thickness selection range of the third rubber frame layer "0.6 - 1" can be, for example, 0.6, 0.7, 0.8, 0.9, or 1, etc.

[0041] In the present invention, by precisely controlling the thickness ratios among the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer, a non-linear stress-strain curve can be achieved through hierarchical response, precisely regulating the mechanical properties of the overall buffer rubber frame, meeting the customer's requirements for a specific stress-strain curve of the buffer rubber frame, thereby precisely controlling the stress distribution during the dynamic compression of the square shell battery cell and meeting the complex mechanical requirements of the dynamic expansion of the battery cell, which is beneficial to improving the structural safety and functional stability of the battery pack.

[0042] Preferably, the thickness of the buffer rubber frame is 2.5 - 3.5 mm, and can be, for example, 2.5 mm, 3 mm, or 3.5 mm, etc.

[0043] Preferably, the hardness of the first rubber frame layer < the hardness of the third rubber frame layer.

[0044] In the present invention, when the battery cell expands, the first rubber frame layer preferentially compresses to absorb energy. As the compression amount increases, the third rubber frame layer and the second rubber frame layer are successively involved in bearing the force, and a non-linear stress-strain curve is achieved through hierarchical response, thus precisely matching the customer's requirements.

[0045] Preferably, the buffer rubber frame formed by the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer satisfies the following stress-strain relation formula:

[0046]

[0047] Wherein, is the strain value of the buffer rubber frame, with the unit of %; a is the layer thickness of the first rubber frame layer, with the unit of mm; b is the layer thickness of the third rubber frame layer, with the unit of mm; c is the layer thickness of the second rubber frame layer, with the unit of mm; is the stress borne by the overall buffer rubber frame, with the unit of MPa; and are respectively the stress-strain relation functions of the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer.

[0048] It should be noted that the above stress-strain relation formula needs to meet the following conditions:

[0049] 1) The buffer rubber frame is a multi-layer structure arranged in a laminated manner; 2) Only the normal compressive stress perpendicular to each layer is applied during the life cycle of the buffer rubber frame; 3) The area of each rubber frame layer in the buffer rubber frame is equal.

[0050] It should be noted that, and The specific stress-strain relation function formulas of and depend on their respective specific materials and can be obtained through their respective stress-strain curves.

[0051] In the present invention, through the combination of glue frame layers with different thicknesses, different types, and different hardnesses, the stiffness of the glue frame layer can be combined to obtain almost all stiffness values between the hardest rubber and the softest rubber, that is, a finite number of materials can express an infinite number of mechanical properties (stress-strain relationships).

[0052] Preferably, when the buffer glue frame is a multi-layer structure, a mesh reinforcing material is embedded between layers.

[0053] In the present invention, by embedding a mesh reinforcing material between layers, the overall tear resistance of the buffer glue frame can be improved.

[0054] Preferably, the mesh reinforcing material includes any one or a combination of at least two of nylon fiber, polypropylene reinforced fiber woven fabric, aramid fiber, glass fiber, or nanofiber reinforcing material (such as magnesium aluminum silicate nanofiber, etc.).

[0055] In a second aspect, the present invention provides a method for preparing a buffer glue frame as described in the first aspect, and the preparation method includes the following steps:

[0056] Select the raw materials of the buffer glue frame, and through compression molding and vulcanization, achieve continuous change of hardness in the thickness direction to obtain a buffer glue frame with a single-layer structure; or stack the first glue frame layer, the second glue frame layer, and the third glue frame layer in sequence, and obtain a buffer glue frame with a multi-layer structure after vulcanization; wherein, the hardness of the first glue frame layer < the hardness of the second glue frame layer > the hardness of the third glue frame layer.

[0057] It should be noted that the vulcanization speed difference between each layer should be < 10%, so as to avoid delamination between layers.

[0058] Preferably, the first glue frame layer, the second glue frame layer, and the third glue frame layer are combined through an adhesive. Exemplarily, the adhesive can be a resorcinol-formaldehyde-hexamethylenetetramine system (HRH) or a cobalt salt bonding system, etc.

[0059] Preferably, the first glue frame layer, the second glue frame layer, and the third glue frame layer are stacked in sequence by using 3D printing method.

[0060] In the present invention, the use of 3D printing technology can realize the construction of a buffer glue frame with a multi-layer structure, which is beneficial to improving the design freedom. In a third aspect, the present invention provides a square shell battery cell, and the square shell battery cell includes the buffer glue frame as described in the first aspect.

[0061] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] (1) The buffer rubber frame structure provided by the present invention precisely regulates the mechanical properties of the overall buffer rubber frame, meets the customer's requirements for a specific stress-strain curve of the buffer rubber frame, thereby precisely controlling the stress distribution during the dynamic compression of the square shell battery cell, meeting the complex mechanical requirements of the dynamic expansion of the battery cell, and being beneficial to improving the structural safety and functional stability of the battery pack.

[0064] (2) The present invention provides a multi-layer structure buffer rubber frame constructed by rubber frame layers of different hardnesses. The multi-layer structure disperses stress concentration, can delay material fatigue, and improve the service life of the buffer rubber frame.

[0065] (3) The buffer rubber frame structure provided by the present invention is applicable to square shell battery cells of different sizes and expansion rates, greatly improving the flexibility of battery pack design. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic structural diagram of the buffer rubber frame provided in Embodiment 1 of the present invention.

[0067] Figure 2 are the stress-strain curves of the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer respectively in the buffer rubber frame provided in Embodiment 1 of the present invention.

[0068] Figure 3 are the stress-strain curves of the buffer rubber frames provided in Embodiment 1 and Embodiments 3-6 of the present invention.

[0069] Among them, 1 - the first rubber frame layer; 2 - the second rubber frame layer; 3 - the third rubber frame layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0071] Embodiment 1

[0072] This embodiment provides a buffer rubber frame. The buffer rubber frame is a multi-layer structure, and its schematic structural diagram is as Figure 1 shown, including the first rubber frame layer 1, the second rubber frame layer 2, and the third rubber frame layer 3 arranged in a stacked manner, and the hardness of the first rubber frame layer 1 < the hardness of the second rubber frame layer 2 > the hardness of the third rubber frame layer 3, and the hardness of the first rubber frame layer 1 < the hardness of the third rubber frame layer 3.

[0073] Among them, the rubber material of the first rubber frame layer 1 is soft silicone rubber, the rubber material of the second rubber frame layer 2 is fluororubber, and the rubber material of the third rubber frame layer 3 is ethylene propylene diene monomer rubber; the thickness of each of the first rubber frame layer 1, the second rubber frame layer 2, and the third rubber frame layer 3 is 1 mm, and the thickness ratio is 1:1:1.

[0074] Among them, the buffer rubber frame formed by the first rubber frame layer 1, the second rubber frame layer 2, and the third rubber frame layer 3 satisfies the following stress-strain relationship formula:

[0075]

[0076] Among them, is the strain value of the buffer rubber frame, with the unit of %; a is 1 mm, b is 1 mm, and c is 1 mm; is the stress received by the overall buffer rubber frame, with the unit of MPa; and are the stress-strain relationship functions of the first rubber frame layer 1, the second rubber frame layer 2, and the third rubber frame layer 3 respectively, and can be deduced through the stress-strain curve shown in Figure 2 shown.

[0077] This embodiment also provides a preparation method for the above buffer rubber frame. The preparation method includes the following steps:

[0078] Stack the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer in sequence, and bond them through the adhesive between m-aminophenol and white system (HRH). After vulcanization, the buffer rubber frame with a multi-layer structure is obtained.

[0079] Embodiment 2

[0080] This embodiment provides a buffer rubber frame. The buffer rubber frame is a single-layer structure. The thickness of the buffer rubber frame is 3 mm, and the hardness of the buffer rubber frame changes continuously along the thickness direction. The continuous change method is: the hardness of the buffer rubber frame continuously decreases from the middle of the layer thickness to both sides of the layer thickness from 60A to 40A.

[0081] The rubber material of the buffer rubber frame is foamed rubber.

[0082] This embodiment also provides a preparation method for the above buffer rubber frame. The preparation method includes the following steps:

[0083] Select the raw materials of the buffer rubber frame, and then through molding and vulcanization, realize the continuous change of hardness in the thickness direction to obtain a buffer rubber frame with a single-layer structure.

[0084] Embodiment 3

[0085] The difference between this embodiment and Embodiment 1 is that the thickness of the first rubber frame layer is 0.6 mm, the thickness of the second rubber frame layer is 1.5 mm, and the thickness of the third rubber frame layer is 0.9 mm, and the thickness ratio is 0.6:1.5:0.9.

[0086] The rest of the preparation methods and parameters are the same as those in Embodiment 1.

[0087] Example 4

[0088] The difference between this example and Example 1 is that the thickness of the first glue frame layer is 1.5 mm, the thickness of the second glue frame layer is 0.6 mm, and the thickness of the third glue frame layer is 0.9 mm, and the thickness ratio is 1.5:0.6:0.9.

[0089] The remaining preparation methods and parameters are the same as those in Example 1.

[0090] Example 5

[0091] The difference between this example and Example 1 is that the thickness of the first glue frame layer is 0.3 mm, the thickness of the second glue frame layer is 2.1 mm, and the thickness of the third glue frame layer is 0.6 mm, and the thickness ratio is 0.3:2.1:0.6.

[0092] The remaining preparation methods and parameters are the same as those in Example 1.

[0093] Example 6

[0094] The difference between this example and Example 1 is that the thickness of the first glue frame layer is 2.1 mm, the thickness of the second glue frame layer is 0.3 mm, and the thickness of the third glue frame layer is 0.6 mm, and the thickness ratio is 2.1:0.3:0.6.

[0095] The remaining preparation methods and parameters are the same as those in Example 1.

[0096] Figure 3 The stress-strain curves of the buffer glue frames provided in Example 1 and Examples 3-6 are shown. It can be seen from the figure that by adjusting the thickness of different layers to meet different functional relationships, the purpose of artificially combining new stress-strain curves can be achieved.

[0097] Example 7

[0098] The difference between this example and Example 1 is that a net-shaped reinforcing material is embedded between adjacent layers of the first glue frame layer, the second glue frame layer and the third glue frame layer, and the net-shaped reinforcing material is nylon fiber.

[0099] The remaining preparation methods and parameters are the same as those in Example 1.

[0100] Example 8

[0101] The difference between this example and Example 1 is that the first glue frame layer, the second glue frame layer and the third glue frame layer are not combined by adhesives, but are laminated by 3D printing.

[0102] The remaining preparation methods and parameters are the same as those in Example 1.

[0103] Example 9

[0104] The difference between this example and Example 1 is that the first glue frame layer is doped with a modified material, and the modified material is N330 carbon black with a doping fraction of 20 wt%; the second glue frame layer is doped with a modified material, and the modified material is talcum powder with a doping fraction of 15 wt%; the third glue frame layer is doped with a modified material, and the modified material is SEBS thermoplastic elastomer with a doping fraction of 8 wt%.

[0105] The remaining preparation methods and parameters are the same as those in Example 1.

[0106] Example 10

[0107] The difference between this example and Example 2 is that the buffer glue frame is doped with a modified material, and the modified material is N330 carbon black, and the doping proportion of the modified material in the buffer glue frame is 20 wt%.

[0108] The remaining preparation methods and parameters are the same as those in Example 1.

[0109] Example 11

[0110] The difference between this example and Example 1 is that the thickness of the first glue frame layer is 0.2 mm, the thickness of the second glue frame layer is 2.1 mm, and the thickness of the third glue frame layer is 1 mm, and the thickness ratio is 0.2:2.1:1.

[0111] The remaining preparation methods and parameters are the same as those in Example 1.

[0112] Example 12

[0113] The difference between this example and Example 1 is that the thickness of the first glue frame layer is 2.1 mm, the thickness of the second glue frame layer is 0.2 mm, and the thickness of the third glue frame layer is 1 mm, and the thickness ratio is 2.1:0.2:1.

[0114] The remaining preparation methods and parameters are the same as those in Example 1.

[0115] Example 13

[0116] The difference between this example and Example 1 is that the thickness of the first glue frame layer is 1 mm, the thickness of the second glue frame layer is 0.2 mm, and the thickness of the third glue frame layer is 1 mm, and the thickness ratio is 1:0.2:1.

[0117] The remaining preparation methods and parameters are the same as those in Example 1.

[0118] Example 14

[0119] The difference between this embodiment and Embodiment 1 is that the thickness of the first glue frame layer is 1 mm, the thickness of the second glue frame layer is 2.1 mm, the thickness of the third glue frame layer is 0.5 mm, and the thickness ratio is 1:2.1:0.5.

[0120] The remaining preparation methods and parameters are the same as those in Embodiment 1.

[0121] Comparative Example 1

[0122] The difference between this comparative example and Embodiment 1 is that the first glue frame layer is not provided.

[0123] The remaining preparation methods and parameters are the same as those in Embodiment 1.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Embodiment 1 is that the second glue frame layer is not provided.

[0126] The remaining preparation methods and parameters are the same as those in Embodiment 1.

[0127] Comparative Example 3

[0128] The difference between this comparative example and Embodiment 1 is that the third glue frame layer is not provided.

[0129] The remaining preparation methods and parameters are the same as those in Embodiment 1.

[0130] Comparative Example 4

[0131] The difference between this comparative example and Embodiment 1 is that the material of the first glue frame layer is fluororubber, the material of the second glue frame layer is soft silicone rubber, and the material of the third glue frame layer is fluororubber, so that the hardness of the first glue frame layer > the hardness of the second glue frame layer < the hardness of the third glue frame layer.

[0132] The remaining preparation methods and parameters are the same as those in Embodiment 1.

[0133] Comparative Example 5

[0134] The difference between this comparative example and Embodiment 1 is that the material of the second glue frame layer is ethylene propylene diene monomer rubber and the material of the third glue frame layer is fluororubber, so that the hardness of the first glue frame layer < the hardness of the second glue frame layer < the hardness of the third glue frame layer.

[0135] The remaining preparation methods and parameters are the same as those in Embodiment 1.

[0136] Comparative Example 6

[0137] The difference between this comparative example and Embodiment 2 is that the hardness of the buffer glue frame does not change along the thickness direction.

[0138] The remaining preparation methods and parameters are the same as those in Embodiment 2.

[0139] Performance test

[0140] The buffer rubber frames provided in the above embodiments and comparative examples were respectively subjected to compression tests. The deviation degree between the compression curves was obtained through comparative experiments, and the safety factor was calculated by comprehensively considering the material strength of the buffer rubber frames to verify the structural safety and functional stability of the battery pack.

[0141] The specific test method includes:

[0142] Place the buffer rubber frame between the pressure plates of an electronic universal material testing machine and perform linear compression at a speed of 1 mm / min until the pressure reaches 40 kN and then stop, and output the experimental results.

[0143] The test results are shown in Table 1.

[0144] Table 1

[0145]

[0146]

[0147] Analysis:

[0148] As can be seen from Table 1, the buffer rubber frame structure provided by the present invention precisely regulates the overall mechanical properties of the buffer rubber frame, meets the customer's requirements for a specific stress-strain curve of the buffer rubber frame, thereby precisely controlling the stress distribution during the dynamic compression of the square shell battery cell, meeting the complex mechanical requirements of the dynamic expansion of the battery cell, and being beneficial to improving the structural safety and functional stability of the battery pack.

[0149] As can be seen from Example 1 and Example 7, if a mesh reinforcing material is embedded between the layers of the first rubber frame layer, the second rubber frame layer and the third rubber frame layer, the overall tear resistance of the buffer rubber frame can be improved, which is beneficial to improving the structural safety and functional stability of the battery pack.

[0150] As can be seen from Example 1 and Example 9, if each rubber frame layer is doped with a modified material with a specific doping fraction, it is beneficial to improve the tensile strength, wear resistance, balance of elasticity and strength, stiffness, heat resistance, gas barrier property, damping property, tear resistance, fatigue resistance, compression modulus, low-temperature toughness, resilience, impact strength and other properties of the material, and can also delay thermal oxygen aging, improve surface ozone resistance and flame retardancy and other properties.

[0151] As can be seen from Example 2 and Example 10, if the buffer rubber frame is doped with a modified material, it is beneficial to improve the tensile strength, wear resistance, balance of elasticity and strength, stiffness, heat resistance, gas barrier property, damping property, tear resistance, fatigue resistance, compression modulus, low-temperature toughness, resilience, impact strength and other properties of the material, and can also delay thermal-oxidative aging, improve surface ozone resistance and flame retardancy and other properties.

[0152] As can be seen from Example 1 and Examples 11-12, if the thickness ratio of the first rubber frame layer and the second rubber frame layer is too small, the absorption effect of the outer first rubber frame layer on the impact force is poor when the battery cell is subjected to vibration and impact; if the thickness ratio of the first rubber frame layer and the second rubber frame layer is too large, it is not conducive to maintaining the shape of the rubber frame layer, resulting in excessive overall deformation and tearing damage of the rubber frame.

[0153] As can be seen from Example 1 and Examples 13-14, if the thickness ratio of the second rubber frame layer and the third rubber frame layer is too small, it is not conducive to maintaining the shape of the rubber frame layer, resulting in excessive overall deformation and tearing damage of the rubber frame; if the thickness ratio of the second rubber frame layer and the third rubber frame layer is too large, the absorption effect of the outer third rubber frame layer on the impact force is poor when the battery cell is subjected to vibration and impact.

[0154] As can be seen from Example 1 and Comparative Examples 1-3, if the first rubber frame layer is not provided, the harder second rubber frame layer will directly contact the force when the battery cell is subjected to vibration and impact, and the battery cell lacks flexible buffering, which is likely to affect the safety of the battery cell; if the second rubber frame layer is not provided, the rubber frame layer will be deformed and twisted too much during continuous use and cannot maintain its original shape, thus causing the support effect on the battery cell to fail; if the third rubber frame layer is not provided, the harder second rubber frame layer will directly contact the force when the battery cell is subjected to vibration and impact, and the battery cell lacks flexible buffering, which is likely to affect the safety of the battery cell.

[0155] As can be seen from Example 1 and Comparative Example 4, if the hardness of the first rubber frame layer > the hardness of the second rubber frame layer < the hardness of the third rubber frame layer, the harder second rubber frame layer will directly contact the force when the battery cell is subjected to vibration and impact, and the battery cell lacks flexible buffering.

[0156] As can be seen from Example 1 and Comparative Example 5, if the hardness of the first rubber frame layer < the hardness of the second rubber frame layer < the hardness of the third rubber frame layer, the harder third rubber frame layer will directly contact the force when the battery cell is subjected to vibration and impact, and the battery cell lacks flexible buffering, which is likely to affect the safety of the battery cell.

[0157] As can be seen from Example 2 and Comparative Example 6, if the hardness of the buffer rubber frame does not change along the thickness direction, it cannot meet the diverse mechanical property requirements of customers, and the structural safety and functional stability of the battery pack are poor.

[0158] It should be noted that the present invention illustrates the process method of the present invention through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A buffer rubber frame, characterized in that, The buffer rubber frame is a single-layer structure or a multi-layer structure; Among them, when the buffer rubber frame is a single-layer structure, the hardness of the buffer rubber frame continuously changes along the thickness direction; when the buffer rubber frame is a multi-layer structure, it includes a first rubber frame layer, a second rubber frame layer, and a third rubber frame layer arranged in layers, and the hardness of the first rubber frame layer < the hardness of the second rubber frame layer > the hardness of the third rubber frame layer.

2. The buffer rubber frame according to claim 1, wherein, When the buffer rubber frame is a single-layer structure, the rubber material of the buffer rubber frame includes foamed rubber.

3. The buffer rubber frame according to claim 1 or 2, characterized in that, When the buffer rubber frame is a single-layer structure, the continuous change mode of the hardness of the buffer rubber frame along the thickness direction is: The hardness of the buffer rubber frame continuously decreases from the middle of the layer thickness to both sides of the layer thickness from 60A to 40A.

4. The buffer rubber frame according to any one of claims 1-3, characterized in that The buffer rubber frame is doped with a modification material, and the modification material includes any one or a combination of at least two of carbon black materials, silicate materials, fiber reinforcements, toughening modifiers, or functional additives; Preferably, when the buffer rubber frame is a single-layer structure, the total proportion of the modification material in the buffer rubber frame ≤ 50wt%; Preferably, when the buffer rubber frame is a multi-layer structure, the total proportion of the modification material in each rubber frame layer is independently ≤ 50wt%.

5. The buffer rubber frame according to any one of claims 1-4, characterized in that The rubber material of the first rubber frame layer includes any one or a combination of at least two of soft silicone rubber, natural rubber, polyurethane elastomer, styrene-butadiene rubber, or cis-butadiene rubber; Preferably, the rubber material of the second rubber frame layer includes any one or a combination of at least two of fluororubber, hydrogenated nitrile rubber, chlorinated ether rubber, or acrylate rubber; Preferably, the rubber material of the third rubber frame layer includes any one or a combination of at least two of ethylene propylene diene monomer rubber, butyl rubber, chloroprene rubber, or ethylene-vinyl acetate rubber; Preferably, the thickness ratio of the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer is (0.3 - 2.1):(0.3 - 2.1):(0.6 - 1); Preferably, the thickness of the buffer rubber frame is 2.5 - 3.5mm; Preferably, the hardness of the first rubber frame layer < the hardness of the third rubber frame layer.

6. The buffer rubber frame according to any one of claims 1-5, characterized in that, The buffer rubber frame formed by the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer satisfies the following stress-strain relationship: Among them, is the strain value of the buffer rubber frame, with the unit of %; a is the layer thickness of the first rubber frame layer, with the unit of mm; b is the layer thickness of the third rubber frame layer, with the unit of mm; c is the layer thickness of the second rubber frame layer, with the unit of mm; is the stress received by the whole buffer rubber frame, with the unit of MPa; and are the stress-strain relationship functions of the first rubber frame layer, the second rubber frame layer and the third rubber frame layer respectively.

7. The buffer rubber frame according to any one of claims 1-6, characterized in that, When the buffer rubber frame is a multi-layer structure, a mesh reinforcing material is embedded between layers; Preferably, the mesh reinforcing material includes any one or a combination of at least two of nylon fiber, polypropylene reinforced fiber woven cloth, aramid fiber, glass fiber, or nanofiber reinforcing material.

8. A method for preparing a buffer rubber frame according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: Select the raw materials of the buffer rubber frame, and through compression molding and vulcanization, realize the continuous change of hardness in the thickness direction to obtain a buffer rubber frame with a single-layer structure; or stack the first rubber frame layer, the second rubber frame layer, and the third rubber frame layer in sequence, and obtain a buffer rubber frame with a multi-layer structure after vulcanization; among them, the hardness of the first rubber frame layer < the hardness of the second rubber frame layer > the hardness of the third rubber frame layer.

9. The preparation method according to claim 8, characterized in that, The first rubber frame layer, the second rubber frame layer, and the third rubber frame layer are combined through an adhesive; or, The first rubber frame layer, the second rubber frame layer, and the third rubber frame layer are stacked in sequence by using 3D printing.

10. A square shell battery cell, characterized in that, The square shell battery cell includes the buffer rubber frame according to any one of claims 1 - 7.

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