Debonding and disassembly analysis method of battery modules

Abstract

The present invention provides a debonding and disassembling analysis method for a battery module, which is used to estimate the disassembling force required to disassemble the battery module from the lower base of the battery pack. The method establishes a module disassembly simulation model, and uses the finite element method in the module disassembly simulation model to divide the area where the battery module and the lower base are bonded into a unit stiffness matrix of multiple nodes, and assigns the properties, type, and thickness of the materials involved in the bonding to the module disassembly simulation model. The external load force of the battery module is simulated and disassembled, and the node displacement vector of each node and the equivalent stress of the corresponding unit stiffness matrix are calculated; when the adhesive material enters the plastic stress stage from the elastic stress stage, the value of the external load force is the disassembly force required to disassemble the battery module. The debonding and disassembly analysis method for the battery module of the present invention is beneficial to reducing the abnormal separation of the thermal conductive structural adhesive at the module bonding point, the damage of the insulating film, and the like that may be caused by disassembly.

Description

Technical Field

[0001] This invention relates to the field of power battery repair and maintenance technology, and in particular to a method for analyzing the debonding of battery modules. Background Technology

[0002] In recent years, new energy vehicles have become increasingly popular, among which electric vehicles powered by power batteries have experienced rapid development, and numerous power battery companies have entered the market.

[0003] As one of the three main components of electric new energy vehicles, the performance of power batteries is receiving increasing attention from customers and the public. During normal use of power batteries, routine partial maintenance or upgrades are sometimes required, such as replacing or inspecting some modules; in such cases, disassembly of the modules is necessary.

[0004] In the past, when a battery pack malfunctioned, the entire pack was usually replaced, resulting in excessively high vehicle usage and maintenance costs. However, by inspecting and replacing the problematic modules within the battery pack, the usage and maintenance costs can be reduced.

[0005] However, existing technologies lack research on the process of disassembling battery packs to replace abnormal modules in the batteries. During disassembly, some module components may be damaged and rendered unusable. Abnormal detachment of the thermally conductive adhesive that holds the insulating film between the water-cooling plate and the cell casing may also cause damage and failure of the insulating film, thus affecting the safety and performance of the battery pack.

[0006] Therefore, it is necessary to develop a relevant analysis and evaluation method for module debonding and disassembly in order to estimate the appropriate disassembly force for disassembling battery modules, so as to complete the disassembly process smoothly and reduce damage to related components; thereby ensuring the reliability of the battery pack disassembly process and reducing potential safety hazards caused by battery pack disassembly. Summary of the Invention

[0007] In view of this, the present invention aims to propose a method for analyzing the debonding of battery modules, which facilitates the analysis and estimation of the appropriate disassembly force required for disassembling battery modules, and helps to reduce abnormal detachment of thermal conductive adhesive at module bonding joints and damage to insulating films that may occur during disassembly.

[0008] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0009] A method for analyzing the debonding of a battery module is provided, which is used to estimate the disassembly force required to disassemble the battery module from the lower base of the battery pack, establish a simulation model for module disassembly, and use the finite element method to divide the area where the battery module and the lower base are bonded into a multi-node element stiffness matrix in the module disassembly simulation model, and assign the attributes, types and thicknesses of the disassembly-related components to the module disassembly simulation model.

[0010] In the module disassembly simulation model, the external load force of the battery module is simulated for disassembly, and the nodal displacement column vector {d} of each node and the equivalent stress [σ] of the corresponding element stiffness matrix are obtained under the external load force. When the adhesive material enters the plastic stress stage from the elastic stress stage, the value of the external load force is the disassembly force required to disassemble the battery module.

[0011] Furthermore, the nodal displacement column vector {d} is calculated using the system force equation of the modular disassembly simulation model after introducing boundary conditions: {F}=[k]×{d}; where [k] is the overall system stiffness matrix and {F} is the nodal load column vector.

[0012] Furthermore, the equivalent stress [σ] is obtained at the Gaussian integral point of the element stiffness matrix.

[0013] Furthermore, the equivalent stress [σ] is obtained at the Gaussian integral point of the element stiffness matrix, including:

[0014] At the Gaussian integration point, the strain {ε} at the Gaussian integration point is calculated according to the geometric equation {ε}=[B]×{d}, where [B] is the geometric matrix; the equivalent stress [σ] is derived according to the physical equation [σ]=[D]{ε}, where [D] is the elastic coefficient matrix.

[0015] Furthermore, the module disassembly simulation model is constructed based on the disassembly assembly form of the battery module, including a lower base, an upper support arranged above the lower base, and a connecting bracket connecting the battery module and the upper support; a water-cooling plate is embedded in the lower base, and the battery module is bonded to the water-cooling plate; a lifting device is provided between the lower base and the upper support, and the external load force is provided by the lifting device.

[0016] Furthermore, the connecting bracket includes a first connecting bracket disposed on the upper support, and a second connecting bracket connected between the side of the battery module and the first connecting bracket.

[0017] Furthermore, guide rods are provided at the four corners of the lower base, and the upper support is positioned above the lower base by being guided by each of the guide rods.

[0018] Furthermore, the disassembly-related components include the connecting bracket, the battery module housing, the water-cooling plate, and the guide rod.

[0019] Furthermore, the lifting device is located on one side of the battery module.

[0020] Furthermore, in the module disassembly simulation model, when the battery module is disassembled, a liquid at 75°C to 110°C is simulated to be introduced into the water-cooled plate.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The battery module debonding and disassembly analysis method of the present invention establishes a module disassembly simulation model for the battery module to be disassembled, and uses the finite element method to simulate and calculate the disassembly force required to disassemble the battery module. Moreover, the disassembly force will not cause abnormal detachment of the thermal conductive structural adhesive at the bonding part of the battery module, as well as damage to the water cooling plate, insulating film, etc., which helps to reduce the abnormal detachment of the thermal conductive structural adhesive at the bonding part of the module and damage to the insulating film that may be caused by disassembly.

[0023] Furthermore, by employing the system force equations, as well as the geometric and physical equations of the Gaussian integral points, the nodal displacement column vector {d} and the strain {ε} at the Gaussian integral points can be accurately calculated, and finally the equivalent stress [σ] of the element stiffness matrix can be solved, thereby obtaining the required disassembly force. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are for explaining the invention. The directional terms used, such as front / back, up / down, etc., are only used to indicate relative positional relationships and do not constitute an improper limitation of the invention. In the drawings:

[0025] Figure 1 This is a schematic flowchart of the debonding and disassembly analysis method for the battery module described in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the disassembly assembly structure of the module disassembly simulation model described in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the assembly structure of the battery module, water-cooling plate, and thermally conductive adhesive in the disassembly simulation model of the module disassembly simulation model described in this embodiment of the invention.

[0028] Figure 4 This is a diagram showing the relevant parameter settings for steel in the nonlinear analysis software described in this embodiment of the invention;

[0029] Figure 5This is a diagram showing the relevant parameter settings for the water-cooled plate material in the nonlinear analysis software described in this embodiment of the invention.

[0030] Figure 6 This is a diagram showing the setting of the solution parameters involved in the nonlinear analysis software described in this embodiment of the invention;

[0031] Figure 7 The simulation diagram shows the disassembly force of 1694N and the adhesive stress of 1.41MPa obtained from the module disassembly simulation model described in the embodiment of the present invention.

[0032] Figure 8 The simulation diagram shows a disassembly force of 1694N and a water-cooled plate strain of 0.188% obtained from the module disassembly simulation model described in this embodiment of the invention.

[0033] Figure 9 The simulation diagram shows a disassembly force of 1694N and a water-cooled plate deformation of 3.31mm obtained from the module disassembly simulation model described in this embodiment of the invention.

[0034] Figure 10 The simulation diagram shows the disassembly force of 1694N and the water-cooled plate stress of 53.77MPa obtained from the module disassembly simulation model described in the embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Lower base; 10. Disassembly support position; 100. Guide rod; 101. Water-cooled plate; 102. Thermally conductive structural adhesive;

[0037] 2. Upper support; 20. Disassemble lifting position; 201. First connecting bracket; 202. Second connecting bracket;

[0038] 3. Battery module. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0040] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "back" appear, indicating orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0041] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0042] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] This invention relates to a method for analyzing the debonding and disassembly of a battery module. This method estimates the disassembly force required to remove the battery module 3 from the lower base 1 of the battery pack, facilitating the estimation of the appropriate disassembly force and reducing potential issues such as abnormal detachment of the thermally conductive adhesive at the module's bonding joints and damage to the insulating film during disassembly. An exemplary process of this method is as follows: Figure 1 As shown.

[0044] Overall, the method includes: establishing a simulation model for module disassembly; using the finite element method to divide the area where the battery module 3 and the lower base 1 are bonded into multiple node element stiffness matrices in the module disassembly simulation model; and assigning the properties, types, and thicknesses of the materials involved in the bonding area to the module disassembly simulation model; simulating the external load force for disassembling the battery module 3 in the module disassembly simulation model, and calculating the nodal displacement vectors of each node and the equivalent stress of the corresponding element stiffness matrix under the external load force; and when the bonding material transitions from the elastic stress stage to the plastic stress stage, the value of the external load force is the disassembly force required to disassemble the battery module 3.

[0045] Based on the above design concepts, such as Figure 1 and combined Figure 2 , Figure 3 As shown, the debonding and disassembly analysis method of the battery module in this embodiment can be carried out in the following specific manner.

[0046] A module disassembly simulation model is established to address the bonding arrangement of battery module 3 within the battery pack. Since battery module 3 is primarily bonded to the water-cooling plate 101 at the bottom of the battery pack via its bottom casing, this embodiment provides a widely applicable module disassembly simulation model for assembly disassembly.

[0047] See example 2 and Figure 3As shown, the disassembly assembly structure of the module disassembly simulation model includes a lower base 1, an upper support 2 guided above the lower base 1, and a connecting bracket connecting the battery module 3 and the upper support 2. Preferably, the connecting bracket includes a first connecting bracket 201 disposed on the upper support 2 and a second connecting bracket 202 connected between the side of the battery module 3 and the first connecting bracket 201. To guide the upper support 2 to move up and down, a guide rod 100 can be provided at each of the four corners of the lower base 1, guiding the upper support 2 above the lower base 1 via the guide rods 100.

[0048] Obviously, in order to remove the entire battery module 3 from the lower base 1, at least two sets of connecting brackets should be provided, with the two sets of connecting brackets located on both sides of the battery module 3, so that the battery module 3 is subjected to force evenly.

[0049] A water-cooling plate 101 is embedded in the lower base 1, and the battery module 3 is bonded to the water-cooling plate 101. A lifting device is provided between the lower base 1 and the upper support 2, and the external load force is provided by the lifting device. When actually disassembling the battery module 3, the lifting device can be a jack. During disassembly, only one jack can be set on one side of the battery module 3 to lift the upper support 2, or one jack can be set on each side of the battery module 3 to lift and disassemble simultaneously. Naturally, in the simulation calculation of the module disassembly simulation model, the same simulation calculation should be performed based on the number and location of the lifting devices used in the actual disassembly.

[0050] In this embodiment, a lifting device is provided, located on one side of the battery module 3; such as Figure 2 As shown, the lifting device is placed on the disassembly support position 10 at the end of the lower base 1, and the top of the lifting device presses against the disassembly lifting position 20 on the lower surface of the upper support 2.

[0051] Based on the disassembly assembly form of the module disassembly simulation model established above, the method of this invention uses the finite element method to perform structural static analysis on the module disassembly. By solving the basic governing equations of the structure, the stiffness matrix, displacement column vector, load column vector, and other data of all nodes in the disassembly model are obtained. Previously, it was necessary to assign the attributes, types, and thicknesses of the disassembly-related components to the module disassembly simulation model. Based on the structure of the disassembly assembly mentioned above, the disassembly-related components here include the connecting bracket, the housing of the battery module 3, the water-cooling plate 101, and the guide rod 100; including the material, stress coefficient, type, thickness, and other related parameters of these components.

[0052] It should be noted that the simulation calculations of this invention need to fully consider the nonlinear constitutive relationship of the component materials, and the analysis and calculations can be performed using existing nonlinear analysis software. Figure 4 and Figure 5The relevant parameter settings for steel (for connecting brackets and guide rods 100) and water-cooled plate materials in the analysis software are shown respectively.

[0053] During the analysis and solution process, the nonlinear analysis software involves setting solution parameters. To fully and accurately examine the stress and deformation of the water-cooled plate 101 during the entire module disassembly process, it is necessary to set the contact between the disassembly fixture and the water-cooled plate 101, the contact between the guide rod 100 and the lower base 1 and the upper support 2, etc. Simultaneously, geometric nonlinearity, material nonlinearity, and contact nonlinearity need to be considered. The relevant parameter settings are as follows: Figure 6 As shown.

[0054] After completing the above settings, simulation can be performed, and the equivalent stress [σ] of the element stiffness matrix can be solved. Based on the fundamental theory of finite element analysis and the plastic behavior of materials, if the system of the module disassembly simulation model is subjected to external loads, its force equations can be obtained as follows:

[0055] {F}=[k]x{d} (1)

[0056] Where [k] is the overall stiffness matrix of the system, {d} is the column vector of nodal displacements, and {F} is the column vector of nodal loads.

[0057] After introducing boundary conditions, solving equation (1) yields the nodal displacement column vector {d}; after obtaining the displacement solution, the strain solution and stress solution can be solved.

[0058] It should be noted that the analysis load and boundary are established based on the disassembly assembly form of the module disassembly simulation model in this embodiment. The analysis boundary is the mounting holes of the four guide rods 100 on the lower base 1, which are used to fully constrain the x and y degrees of freedom of some nodes at one end of the water-cooled plate 101.

[0059] Under normal temperature conditions, the external load applied to the end of the upper support 2 is approximately 7497N, which can be adjusted according to the actual situation. However, in the module disassembly simulation model of this embodiment, and in actual disassembly, to improve the efficiency and safety of disassembly and reduce potential damage, the battery module 3 is disassembled under high temperature conditions. During this process, when simulating the disassembly of the battery module 3 in the module disassembly simulation model, liquid at 75℃~110℃ is simulated to be introduced into the water-cooled plate 101 to raise the temperature of the bonding parts of the battery module 3. The same heating operation is also used in actual disassembly.

[0060] Based on the above solution of equation (1), the nodal displacement column vector {d} is obtained, and the strain and stress are first obtained at the Gaussian integration point of the element.

[0061] At the Gaussian integration points, the calculation is performed according to the following geometric equations:

[0062] {ε}=[B]x{d} (2)

[0063] The strain {ε} at the Gaussian integration point can be calculated according to equation (2), where [B] is the geometric matrix.

[0064] Then, based on Hooke's law and geometric equations, the stress is derived, i.e., the following physical equation (3), to calculate the stress at the Gaussian integral point.

[0065] [σ]=[D][B]{d}=[D] {ε} (3)

[0066] Where [σ] is the stress at the Gaussian integration point, and [D] is the elastic coefficient matrix, i.e., the usual elastic modulus E.

[0067] After considering the nonlinear constitutive relationship of the material, under the action of external load, the material will gradually enter the plastic stage after going through the elastic stage. At this time, the stress obtained is plastic stress and plastic strain. This is exactly the disassembly force required to remove the battery module 3 without causing abnormal detachment of the thermally conductive adhesive 102 at the bonding joint of the battery module 3 or damage to the insulating film.

[0068] Through the above calculations, the disassembly force can be obtained under the condition that the thermally conductive structural adhesive 102 is completely detached and the water-cooled plate 101 is not damaged. Meanwhile, as... Figure 1 As shown, when the calculation results are difficult to converge during the integral solution process, it may be due to unreasonable settings of the model and its connection parameters, or unreasonable settings of the relevant parameters for the solution. The relevant parameters should be adjusted through cause analysis.

[0069] like Figures 7-10 As shown, when the disassembly force is 1694N, the stress of the thermally conductive structural adhesive is 1.41MPa, which is less than the failure threshold of 1.5MPa. The plastic strain of the water-cooled plate 101 is 0.188%, which is less than 0.2%. The deformation of the water-cooled plate 101 is only 3.31mm, which will not cause the failure of the water-cooled plate 101. The stress of the water-cooled plate 101 is 53.77MPa, which is less than 54MPa. At this time, the water-cooled plate 101 and the brazed joint of the flow channel will not be damaged.

[0070] Based on the above simulation calculations and theoretical analysis, it is recommended that during actual operation, the disassembly force required to remove the adhesive from the water-cooling plate 101 during battery module 3 disassembly should be less than 1700N. This ensures the integrity of the thermally conductive adhesive 102 and prevents cracking at the brazing joints of the water-cooling plate 101 flow channels. The following table shows the theoretical analysis results of module debonding and disassembly:

[0071]

[0072] Through the above simulation calculations and theoretical analysis, the obtained disassembly force value can be applied to the actual disassembly of battery module 3, ensuring normal disassembly of the module and preventing damage to individual components, allowing them to continue normal use. For example, the insulating film between the water-cooling plate 101 and the casing of the battery module 3 can be normally separated from the thermally conductive structural adhesive 102. The analysis process and evaluation method of this invention provide an efficient analysis method and approach for quickly identifying the disassembly force of the module, which can greatly reduce the R&D costs of enterprises and has a positive effect on the safety and service life of the entire battery pack.

[0073] This method can significantly shorten the module disassembly process and provide a good reference for module and overall package modifications. Furthermore, it fully considers the relationships between components within the module, focusing on the detachment of the water-cooled plate 101 and the thermally conductive adhesive 102 during module disassembly, which has significant guiding value for practical engineering.

[0074] In summary, the battery module debonding and disassembly analysis method of this embodiment, by establishing a module disassembly simulation model for the battery module 3 to be disassembled, can simulate and calculate the disassembly force required to disassemble the battery module 3 using the finite element method. Moreover, this disassembly force will not cause abnormal detachment of the thermally conductive structural adhesive 102 at the bonding part of the battery module 3, or damage to the water-cooling plate 101, insulating film, etc., which helps to reduce the abnormal detachment of the thermally conductive structural adhesive at the bonding part of the module and damage to the insulating film that may be caused by disassembly.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for analyzing the debonding and disassembly of a battery module, used to estimate the disassembly force required to disassemble the battery module (3) from the lower base (1) of the battery pack, characterized in that: A simulation model for module disassembly is established. In the simulation model, the area where the battery module (3) and the lower base are bonded is divided into a multi-node element stiffness matrix using the finite element method. The attributes, types, and thicknesses of the disassembled components are assigned to the simulation model. The external load force of disassembling the battery module (3) is simulated in the simulation model, and the nodal displacement column vector {d} of each node and the equivalent stress [σ] of the corresponding unit stiffness matrix are calculated under the external load force. When the adhesive material enters the plastic stress stage from the elastic stress stage, the value of the external load force is the disassembly force required to disassemble the battery module (3). The simulation model is constructed based on the disassembled assembly form of the battery module (3), including a lower base (1), an upper support (2) which is guided above the lower base (1), and a connecting bracket connecting the battery module (3) and the upper support (2); a water-cooled plate (101) is embedded on the lower base (1), and the battery module (3) is bonded to the water-cooled plate (101); a lifting device is provided between the lower base (1) and the upper support (2), and the external load force is provided by the lifting device.

2. The method for debonding and disassembling a battery module according to claim 1, characterized in that: The nodal displacement column vector {d} is calculated using the system force equations of the simulation model after introducing boundary conditions: {F}=[k]×{d}; where [k] is the overall stiffness matrix of the system, and {F} is the column vector of nodal loads.

3. The method for debonding and disassembling a battery module according to claim 2, characterized in that: The equivalent stress [σ] is obtained at the Gaussian integral point of the element stiffness matrix.

4. The method for debonding and disassembling a battery module according to claim 3, characterized in that: The equivalent stress [σ] is obtained at the Gaussian integral point of the element stiffness matrix, including: At the Gaussian integration point, the strain {ε} at the Gaussian integration point is calculated according to the geometric equation {ε}=[B]×{d}, where [B] is the geometric matrix; The equivalent stress [σ] is derived from the physical equation [σ]=[D]{ε}, where [D] is the elastic coefficient matrix.

5. The method for debonding and disassembling a battery module according to any one of claims 1 to 4, characterized in that: The connecting bracket includes a first connecting bracket (201) disposed on the upper support (2) and a second connecting bracket (202) connected between the side of the battery module (3) and the first connecting bracket (201).

6. The method for debonding and disassembling a battery module according to claim 5, characterized in that: The lower base (1) is provided with guide rods (100) at each of its four corners, and the upper support (2) is positioned above the lower base (1) by the guide rods (100).

7. The method for debonding and disassembling a battery module according to claim 6, characterized in that: The disassembly-related components include the connecting bracket, the housing of the battery module (3), the water-cooling plate (101), and the guide rod (100).

8. The method for debonding and disassembling a battery module according to any one of claims 1 to 4, characterized in that: The lifting device is located on one side of the battery module (3).

9. The method for debonding and disassembling a battery module according to any one of claims 1 to 4, characterized in that: When the battery module (3) is disassembled in the simulation model, liquid at 75°C to 110°C is simulated to be introduced into the water-cooled plate (101).

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