Battery module and battery module manufacturing method

Abstract

This application discloses a battery module and a method for manufacturing the battery module. The battery module includes: multiple battery cells, a first end plate and a second end plate, and multiple elastic buffer pads. The multiple elastic buffer pads are respectively located between the battery cells and the first end plate, between the battery cells and the second end plate, and between adjacent battery cells. Among the multiple elastic buffer pads, the effective thickness of at least some of the elastic buffer pads located between adjacent battery cells is less than the effective thickness of the elastic buffer pads located between the battery cells and the first end plate, and the effective thickness of at least some of the elastic buffer pads located between adjacent battery cells is less than the effective thickness of the elastic buffer pads located between the battery cells and the second end plate. By making the effective thickness of the elastic buffer pads between adjacent battery cells less than the effective thickness of the elastic buffer pads located between the two ends of the battery cells, the pressure deviation of the battery module being lower at both ends and higher in the middle when under pressure is offset, thereby improving the uniformity of pressure distribution within the battery module.

Description

Technical Field

[0001] This application relates to the fields of new energy storage and power battery technology, and in particular to a battery module and a method for manufacturing the battery module. Background Technology

[0002] In existing technologies, to ensure the battery cells are subjected to stress, elastic buffer pads of equal thickness are typically placed between the cells and between the cells and the end plates to absorb the interaction forces between the components within the battery module. However, after the battery module is subjected to preload, due to manufacturing tolerances, casing variations, and other reasons, the pressure distribution inside the battery module casing becomes extremely uneven. Buffer pads of equal thickness cannot compensate for this unevenness and may even exacerbate it. Summary of the Invention

[0003] This application provides a battery module that can compensate for uneven pressure inside the battery module and a method for manufacturing the battery module.

[0004] In a first aspect, this application provides a battery module, including: Multiple battery cells are arranged sequentially along the length of the battery module. The first end plate and the second end plate are respectively disposed at both ends of multiple cells along the length direction of the battery module; Multiple elastic buffer pads are located between the battery cell and the first end plate, between the battery cell and the second end plate, and between adjacent battery cells, respectively. Among the multiple elastic buffer pads, the effective thickness of the elastic buffer pad located between adjacent battery cells is less than the effective thickness of the elastic buffer pad located between the battery cell and the first end plate, and the effective thickness of the elastic buffer pad located between adjacent battery cells is less than the effective thickness of the elastic buffer pad located between the battery cell and the second end plate.

[0005] In some feasible implementations, multiple elastic buffer pads are arranged sequentially at intervals along the length of the battery module, and the thickness of the multiple elastic buffer pads gradually decreases from both ends of the multiple elastic buffer pads towards the middle.

[0006] In some feasible implementations, multiple elastic buffer pads include multiple buffer pad groups, which are arranged sequentially at intervals along the length of the battery module. Each buffer pad group includes at least two adjacent elastic buffer pads, and the elastic buffer pads in each buffer pad group have the same thickness. The thickness of the multiple buffer pad groups gradually decreases from both ends of the multiple buffer pad groups towards the middle.

[0007] In some feasible implementations, the material of the elastic cushioning pad includes at least one of foam, silicone, or rubber.

[0008] Secondly, this application provides a method for manufacturing a battery module. The battery module includes multiple battery cells, multiple elastic buffer pads, a first end plate and a second end plate. The first end plate and the second end plate are respectively located at both ends of the multiple battery cells along the length direction of the battery module. The multiple elastic buffer pads are respectively located between the battery cells and the first end plate, between the battery cells and the second end plate, and between adjacent battery cells. The methods include: Set the reference pressure; Acquire pressure distribution data of the battery module along its length; Determine the pressure compensation values ​​at each location between adjacent cells, between a cell and the first end plate, and between a cell and the second end plate based on the reference pressure and pressure distribution data. The thickness of each elastic buffer pad in its free state is determined based on the pressure compensation value. The larger the pressure compensation value, the larger the thickness of the corresponding elastic buffer pad; the smaller the pressure compensation value, the smaller the thickness of the corresponding elastic buffer pad.

[0009] In some feasible implementations, the pressure distribution data of the battery module along its length is obtained, including: Standard buffer pads are set between the cells of the battery module, between the cells and the first end plate, and between the cells and the second end plate. Lock the first end plate and the second end plate; Collect the pressure values ​​of each standard buffer pad; By fitting the pressure values ​​of each standard buffer pad, the pressure distribution data of the battery module along its length can be obtained.

[0010] In some feasible implementations, the pressure distribution data of the battery module along its length is obtained, including: Standard buffer pads are set between the cells of the battery module, between the cells and the first end plate, and between the cells and the second end plate. Establish a simulation model of the battery module; Apply preload to the first and second end plates; Calculate and extract the contact pressure for each standard cushioning pad; Pressure distribution data are obtained by fitting the contact pressure of each standard cushioning pad.

[0011] In some feasible implementations, the thickness of each elastic cushioning pad in its free state is determined based on the pressure compensation value, including: Determine the baseline thickness based on the standard cushioning pad; The target compression is determined based on the pressure compensation value. When the pressure compensation value is greater than 0, the target compression is positive; when the pressure compensation value is less than 0, the target compression is negative. The thickness of each elastic cushioning pad in its free state is determined based on the baseline thickness and the target compression amount.

[0012] In some feasible implementations, the target compression is determined based on the pressure compensation value, including: Obtain the stress-strain curve of the elastic cushioning pad material; The pressure compensation values ​​at each location between adjacent cells, between a cell and the first end plate, and between a cell and the second end plate are converted into target compression values.

[0013] Among some feasible implementation methods, the approach also includes: Obtain the total length of the battery module; Obtain the tolerances between battery cells, between a battery cell and the first end plate, and between a battery cell and the second end plate; The thickness of each elastic cushioning pad in its free state is obtained based on the total length, tolerance, and target compression.

[0014] By making the effective thickness of the elastic buffer pads between adjacent cells smaller than that between the two ends of the cells, the elastic buffer pads with larger effective thicknesses between the first end plate and the cells, and between the second end plate and the cells, generate greater compressive rebound force after being compressed. The elastic buffer pads with smaller effective thicknesses between adjacent cells reduce the compressive stiffness and load-bearing capacity of the elastic buffer pads in the central area of ​​the battery module. The combination of these two factors offsets the pressure deviation of the battery module when compressed, which is lower at both ends and higher in the middle, ensuring that the normal compressive stress borne by the cells at all locations within the battery module remains consistent. The pressure on the cells located in the middle of the battery module is no longer excessive, suppressing side reactions within the cells and slowing capacity decay. The pressure on the cells located at both ends of the battery module is no longer too low, reducing contact thermal resistance, controlling temperature rise, and slowing internal resistance growth. The mechanical and thermal environments within the battery module tend to be consistent, resulting in a uniform aging rate for each cell and significantly suppressing the phenomenon of a sharp increase in inter-cell pressure difference with the number of cycles, thereby extending the battery pack's lifespan. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application or the background art will be described below.

[0016] Figure 1 This application provides a schematic diagram of the structure of a battery module. Figure 2 This is a schematic diagram of another battery module provided in this application; Figure 3 This is a schematic diagram of another battery module provided in this application; Figure 4 A flowchart illustrating the manufacturing method of the battery module provided in this application.

[0017] Attached image captions: 1000 - Battery module, 100 - Battery cell, 200 - First end plate, 300 - Second end plate, 400 - Elastic buffer pad, 500 - Buffer pad assembly. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the application will be described in further detail below with reference to the accompanying drawings.

[0019] After a preload is applied to a battery module, the actual pressure distribution inside the module becomes extremely uneven due to manufacturing tolerances, differences in cell casing stiffness, and bending deformation under stress. This often results in a "smile curve" distribution, with low pressure at both ends and high pressure in the middle, or even a more complex distribution. Existing technologies using uniform-thickness buffer pads cannot compensate for this unevenness, leading to inconsistent mechanical stress environments between cells. For example, cells with excessive pressure experience high internal stress and accelerated side reactions; cells with insufficient pressure suffer from poor contact, increased surface thermal resistance, and higher temperature rise. When the mechanical and thermal environments are inconsistent, the rate of capacity decay and internal resistance increase differs among cells, directly manifesting as a rapid increase in the pressure difference between cells within the module. This leads to premature degradation of the overall module lifespan, significantly shortening the overall usable lifespan and reliability of the battery pack.

[0020] Please see Figure 1 This application provides a battery module 1000, including: a plurality of battery cells 100 arranged sequentially along the length of the battery module 1000; a first end plate 200 and a second end plate 300 respectively disposed at both ends of the plurality of battery cells 100 along the length of the battery module 1000; and a plurality of elastic buffer pads 400 respectively located between the battery cells 100 and the first end plate 200, between the battery cells 100 and the second end plate 300, and between adjacent battery cells 100. Among the plurality of elastic buffer pads 400, the effective thickness of at least some of the elastic buffer pads 400 located between adjacent battery cells 100 is less than the effective thickness of the elastic buffer pads 400 located between the battery cells 100 and the first end plate 200, and the effective thickness of at least some of the elastic buffer pads 400 located between adjacent battery cells 100 is less than the effective thickness of the elastic buffer pads 400 located between the battery cells 100 and the second end plate 300. The length direction of the battery module is the X-axis direction, and the width direction of the battery module is the Y-axis direction.

[0021] Effective thickness refers to the portion of the elastic buffer pad 400 that can undergo compressive deformation and generate effective rebound force when subjected to external constraint pressure. For example, the stiffness or density of each elastic buffer pad 400 within the battery module 1000 may be consistent, but their thicknesses may differ. A thicker elastic buffer pad 400 will produce a greater deformation under pressure, resulting in a greater effective rebound force, and thus a larger effective thickness. Conversely, a thinner elastic buffer pad 400 will produce a smaller deformation under pressure, resulting in a smaller effective rebound force, and thus a smaller effective thickness. Alternatively, the thickness of each elastic buffer pad 400 within the battery module 1000 may be consistent, but their stiffness or density may differ. A thinner elastic buffer pad 400 will produce a smaller effective rebound force under pressure, resulting in a smaller effective thickness; conversely, a thicker elastic buffer pad 400 will produce a greater effective rebound force under pressure, resulting in a larger effective thickness.

[0022] Among the multiple elastic buffer pads 400, the effective thickness of the elastic buffer pad 400 located between adjacent cells 100 may be less than the effective thickness of the elastic buffer pad 400 located between the first end plate 200 and the cell 100 and the effective thickness of the elastic buffer pad 400 located between the second end plate 300 and the cell 100. For example, when the stiffness or density of each elastic buffer pad is consistent but the thickness is inconsistent, the thickness of some elastic buffer pads 400 located between adjacent cells 100 is less than the thickness of the elastic buffer pads 400 located between the first end plate 200 and the cell 100 and the thickness of the elastic buffer pads 400 located between the second end plate 300 and the cell 100; when the stiffness or density of each elastic buffer pad is inconsistent but the thickness is consistent, the stiffness (or density) of some elastic buffer pads 400 located between adjacent cells 100 is less than the stiffness (or density) of the elastic buffer pads 400 located between the first end plate 200 and the cell 100 and the stiffness (or density) of the elastic buffer pads 400 located between the second end plate 300 and the cell 100.

[0023] Among the multiple elastic buffer pads 400, the effective thickness of all elastic buffer pads 400 located between adjacent cells 100 may be less than the thickness of the elastic buffer pad 400 located between the first end plate 200 and the cell 100 and the thickness of the elastic buffer pad 400 located between the second end plate 300 and the cell 100. For example, when the stiffness or density of each elastic buffer pad is consistent but the thickness is inconsistent, the thickness of all elastic buffer pads 400 located between adjacent cells 100 is less than the thickness of the elastic buffer pads 400 located between the first end plate 200 and the cell 100 and the thickness of the elastic buffer pads 400 located between the second end plate 300 and the cell 100; when the stiffness or density of each elastic buffer pad is inconsistent but the thickness is consistent, the stiffness (or density) of all elastic buffer pads 400 located between adjacent cells 100 is less than the stiffness (or density) of the elastic buffer pads 400 located between the first end plate 200 and the cell 100 and the stiffness (or density) of the elastic buffer pads 400 located between the second end plate 300 and the cell 100.

[0024] The following example illustrates the situation where the elastic buffer pads at various locations within the battery module have the same stiffness or density, but inconsistent thickness. When the battery module 1000 is locked, the first end plate 200 and the second end plate 300 apply a preload force to multiple battery cells 100. Due to insufficient contact pressure, microscopic gaps exist between the battery cells 100 at both ends of the battery module 1000 and the end plates or adjacent battery cells 100. By setting thicker elastic buffer pads 400 between the first end plate 200 and the battery cells 100, and between the second end plate 300 and the battery cells 100, the elastic buffer pads 400 generate a larger compressive rebound force after being compressed. This additional support force can actively fill the end gaps caused by bending or tolerance accumulation of the first end plate 200 or the second end plate 300, ensuring that the originally under-compressed battery cells 100 at both ends can obtain sufficient normal pressure, thereby ensuring effective electrical contact and structural stability.

[0025] The cell 100 located in the middle region of the battery module 1000 is subjected to greater compressive stress. By setting a thin elastic buffer pad 400 between adjacent cells 100, the compressive stiffness and load-bearing capacity of the elastic buffer pad 400 in the central region of the battery module 1000 are reduced, so that the compressive load borne by the middle cell 100 can be diverted to both sides of the battery module 1000, thereby reducing the excessive mechanical stress to a safe range and protecting the internal structure of the cell 100 from damage.

[0026] By making the thickness of the elastic buffer pad 400 between adjacent cells 100 less than the thickness of the elastic buffer pad 400 between the two ends of the cell 100, the pressure deviation of the battery module 1000, which is lower at both ends and higher in the middle, is offset, ensuring that the normal compressive stress borne by the cells 100 at all locations within the battery module 1000 remains consistent. The pressure on the cell 100 located in the middle of the battery module 1000 is no longer excessive, side reactions within the cell 100 are suppressed, and capacity decay is slowed. The pressure on the cells 100 located at both ends of the battery module 1000 is no longer too low, reducing contact thermal resistance, controlling temperature rise, and slowing internal resistance growth. The mechanical and thermal environments within the battery module 1000 become more consistent, resulting in a uniform aging rate for each cell 100. This significantly suppresses the phenomenon of a sharp increase in inter-cell pressure difference with the number of cycles within the battery module 1000, thereby extending the battery pack's lifespan.

[0027] Please see Figure 2 In one feasible implementation, multiple elastic buffer pads 400 are arranged sequentially at intervals along the length of the battery module 1000, and the thickness of the multiple elastic buffer pads 400 gradually decreases from both ends towards the middle. It should be noted that the thickness of the multiple elastic buffer pads is symmetrically distributed from the central region of the battery module towards both ends. The thickness of the elastic buffer pads 400 gradually decreases from the first end plate 200 towards the central region of the multiple battery cells 100, and also gradually decreases from the second end plate 300 towards the central region of the multiple battery cells 100. The thickness of the multiple elastic buffer pads 400 gradually decreases from both ends of the battery module 1000 toward the center of the battery module 1000. For example, the thickness of the elastic buffer pad 400 between the battery cell 100 and the first end plate 200 is 2.5 mm. As it moves closer to the center of the battery module 1000, elastic buffer pads 400 with a thickness of 2 mm, 1.5 mm, and 1 mm are used in sequence. Similarly, an elastic buffer pad 400 with a thickness of 2.5 mm is used between the battery cell 100 and the second end plate 300. As it moves closer to the center of the battery module 1000, elastic buffer pads 400 with a thickness of 2 mm, 1.5 mm, and 1 mm are used in sequence.

[0028] Alternatively, the effective thickness of the multiple elastic buffer pads 400 gradually decreases from both ends of the battery module 1000 towards the center. For example, each elastic buffer pad 400 has a uniform thickness, but by controlling the foaming rate or the proportion of filler added inside each elastic buffer pad 400, the material density of the elastic buffer pad 400 closer to the center of the battery module 1000 is lower, making it easier to compress and resulting in a smaller effective thickness; while the material density of the elastic buffer pad 400 located between the first end plate 200 and the cell 100, and the elastic buffer pad 400 located between the second end plate 300 and the cell 100 are higher, making them more difficult to compress and resulting in a larger effective thickness.

[0029] The thickness of the multiple elastic buffer pads 400 gradually decreases from both ends to the middle, ensuring that the support provided by the elastic buffer pads 400 smoothly transitions along the length of the battery module 1000. This structure can fill the gaps caused by the deformation of the first end plate 200 and the second end plate 300, eliminating local stress concentration in the battery module 1000 and making the pressure distribution within the battery module 1000 more uniform. Simultaneously, this structure also allows for a large-area fit between the battery cell 100 and adjacent battery cells 100, increasing the contact pressure in the middle without adding additional stacking burden to the ends. This allows the first end plate 200 and the second end plate 300 to rebound at a reasonable curvature, enabling the pressure at both ends of the battery module 1000 to also rise to the ideal range, thus resulting in a more optimal pressure distribution within the battery module 1000.

[0030] Please see Figure 3 In one feasible implementation, the plurality of elastic buffer pads 400 include a plurality of buffer pad groups 500, which are arranged sequentially at intervals along the length of the battery module 1000. Each buffer pad group 500 includes at least two adjacent elastic buffer pads 400. The elastic buffer pads 400 in each buffer pad group 500 have the same thickness, and the thickness of the plurality of buffer pad groups 500 gradually decreases from both ends of the plurality of buffer pad groups 500 toward the middle.

[0031] Multiple elastic buffer pads 400 are arranged sequentially along the length of the battery module 1000 and divided into multiple buffer pad groups 500. For example, the first group consists of elastic buffer pads 400 near the first end plate 200, the second group consists of elastic buffer pads 400 located on the outermost layer of the battery module 1000, and the third group consists of elastic buffer pads 400 located in the central region of the battery module 1000. From both ends of the battery module 1000 towards the center, the thickness of each group of elastic buffer pads 400 is smaller than that of the previous group. For example, the thickness of the first group of buffer pads near the first end plate 200 is T1, the thickness of the second group of buffer pads on the outermost layer is T2, and the thickness of the third group of buffer pads in the center is T3, where T1 > T2 > T3.

[0032] The thickness of multiple buffer pad groups 500 gradually decreases from both ends to the middle. This not only relieves the greater pressure between the middle battery cells 100, but also provides sufficient contact pressure to the weaker pressure areas at both ends of the battery module 1000, resulting in a more uniform pressure distribution within the battery module 1000. The elastic buffer pads 400 within each buffer pad group 500 have a uniform thickness. This can be achieved by directly utilizing existing standardized buffer pads, cutting them into different thicknesses, and assembling them accordingly. This significantly reduces the manufacturing cost of the elastic buffer pads 400 and improves production efficiency.

[0033] The elastic cushioning pad 400 is made of at least one of foam, silicone, or rubber. The elastic cushioning pad 400 can be foam, such as microporous polyurethane foam or EPDM rubber foam with high resilience. By controlling the density of the foam, such as high-density rigid foam and low-density flexible foam, its compressive stress-strain curve can be adjusted. The elastic cushioning pad 400 can also be silicone, such as solid silicone or liquid silicone. Silicone materials can maintain a stable elastic modulus over a wide temperature range. Silicone has excellent high-temperature resistance and anti-aging properties, and due to its softness, it can conform well to the microscopic unevenness of the battery cell 100 surface. The elastic cushioning pad 400 can also be rubber, such as vulcanized rubber, which can improve support stiffness and is suitable for battery modules 1000 that require high preload.

[0034] Foam, silicone, and rubber are all viscoelastic materials, and their stress-strain curves are non-linear, meaning that stress increases with increasing strain. In the middle of the battery module 1000, the elastic buffer pad 400 is thicker, resulting in greater compressive deformation. Utilizing the material hardening effect, it can provide greater rebound force to absorb the higher pressure between the battery cells 100. At both ends of the battery module 1000, the elastic buffer pads 400 are thinner, resulting in less compressive deformation and providing gentle support. The combination of these materials improves the uniformity of internal pressure within the battery module 1000. Furthermore, these materials all have good compressibility, actively absorbing accumulated tolerances such as height differences between the battery cells 100 and end-plate processing errors, ensuring that each battery cell 100 is compressed after the battery module 1000 is locked.

[0035] Please see Figure 4 This application provides a method for manufacturing a battery module 1000, the method comprising: S101, set the reference pressure.

[0036] The optimal contact pressure range for cell 100 is determined based on factors such as electrolyte retention rate, active material structural stability, and internal resistance characteristics. A specific value within this optimal contact pressure range is then selected as a reference pressure. For example, if the optimal range is 200-300 kPa, the reference pressure can be set to 250 kPa.

[0037] S102, Obtain pressure distribution data of the battery module along its length.

[0038] After a preload is applied, the pressure distribution inside the battery module 1000 becomes uneven due to factors such as bending deformation of the end plate or differences between the casing and the battery cell 100. By acquiring pressure distribution data along the length of the battery module 1000, the stress state inside the battery module 1000 can be accurately identified, and a pressure distribution curve inside the battery module 1000 can be obtained, providing a reference for subsequent calculation of pressure compensation values ​​at various points within the battery module 1000.

[0039] S103, determine the pressure compensation values ​​at each position between adjacent cells, between a cell and the first end plate, and between a cell and the second end plate based on the reference pressure and pressure distribution data.

[0040] The battery module 1000 is divided into several discrete position points along its length. For example, along the length of the battery module 1000, it is divided into position points between every two adjacent cells 100, position points between a cell 100 and the first end plate 200, and position points between a cell 100 and the second end plate 300. The pressure compensation value for each position point is calculated based on the reference pressure and the pressure value at each position point. The formula for calculating the pressure compensation value is:

[0041] In the formula, The set reference pressure is a specific value selected within the optimal contact pressure range of the battery cell, which is determined by the user as needed. This refers to the pressure compensation value at each location within the battery module, i.e., the difference between the reference pressure value and the actual pressure value at each location within the battery module. (x) represents the pressure distribution data, i.e., the actual pressure at each location point within battery module 1000. In areas of low pressure within battery module 1000, the pressure compensation value is greater than 0, indicating that the effective pressure needs to be increased; in areas of high pressure within battery module 1000, the pressure compensation value is less than 0, indicating that excessive pressure needs to be released.

[0042] S104. The thickness of each elastic buffer pad in its free state is determined based on the pressure compensation value. The larger the pressure compensation value, the larger the thickness of the corresponding elastic buffer pad; the smaller the pressure compensation value, the smaller the thickness of the corresponding elastic buffer pad.

[0043] The free state refers to the state where the elastic buffer pad is not under force. Under the premise of satisfying the total length constraint of the battery module or the monotonic relationship between the thickness of the elastic buffer pad and the compensation value, the larger the pressure compensation value at each location point in the battery module, the greater the effective pressure that needs to be increased at that point, the greater the deformation of the elastic buffer pad 400, and the larger the corresponding elastic buffer pad 400. Conversely, the smaller the pressure compensation value, the more pressure needs to be released, the smaller the deformation of the elastic buffer pad 400, and the smaller the corresponding thickness of the elastic buffer pad 400. For example, when the pressure within the battery module 1000 tends to be low at both ends and high in the middle, thinner elastic buffer pads 400 can be placed between adjacent cells 100, and thicker elastic buffer pads 400 can be placed between cell 100 and the first end plate 200, and between cell 100 and the second end plate 300. Alternatively, the thickness of the multiple elastic buffer pads 400 within the battery module 1000 can gradually decrease from both ends of the battery module 1000 towards the center. The multiple elastic buffer pads 400 can also be divided into multiple buffer pad groups 500, with each group having the same thickness, but the thickness of the multiple groups gradually decreasing from both ends of the battery module 1000 towards the center. Or, when the pressure within the battery module 1000 exhibits other complex distributions, thinner elastic buffer pads 400 can be placed in areas of higher pressure, and thicker elastic buffer pads 400 can be placed in areas of lower pressure.

[0044] Through steps S101 to S104, based on the pressure distribution data and reference pressure within the battery module 1000, a mapping relationship is established between the pressure compensation value at each location within the battery module 1000 and the thickness of the elastic buffer pads 400 set at each location. This ensures that the thickness distribution of the elastic buffer pads 400 is opposite to the trend of the pressure distribution within the battery. For example, thicker elastic buffer pads 400 are set in the under-pressure areas at both ends of the battery module 1000, i.e., between the first end plate 200 and the cell 100, and between the second end plate 300 and the cell 100, to provide sufficient contact pressure. In the over-pressure area in the middle of the battery module 1000, i.e., between adjacent cells 100, thinner elastic buffer pads 400 are set to balance the pressure distribution within the battery module 1000. This avoids accelerated lithium plating or bulging of the middle cell 100 due to long-term excessive pressure, and also avoids increased internal resistance and overheating of the cells 100 at both ends due to poor contact. Ultimately, this makes the pressure on all cells 100 within the battery module 1000 more uniform, improving the uniformity of pressure distribution within the battery module 1000. The capacity decay rate of each cell 100 remains synchronized, significantly suppressing the expansion of pressure difference and extending the overall service life of the battery pack.

[0045] Specifically, pressure distribution data along the length of the battery module 1000 can be obtained through actual measurement, including: setting standard buffer pads between the battery cells 100, between the battery cells 100 and the first end plate 200, and between the battery cells 100 and the second end plate 300; locking the first end plate 200 and the second end plate 300; collecting the pressure values ​​of each standard buffer pad; and fitting the pressure values ​​of each standard buffer pad to obtain the pressure distribution data along the length of the battery module 1000.

[0046] Standard buffer pads refer to pads with uniform thickness and material, and these standard buffer pads integrate thin-film pressure sensors. Since standard buffer pads are set between each adjacent cell 100, between cell 100 and the first end plate 200, and between cell 100 and the second end plate 300 within the battery module 1000, and since these standard buffer pads integrate thin-film pressure sensors, it is equivalent to setting thin-film pressure sensors between each adjacent cell 100, between cell 100 and the first end plate 200, and between cell 100 and the second end plate 300 within the battery module 1000 to detect the pressure at various points within the battery module 1000.

[0047] The first end plate 200 and the second end plate 300 can be locked by using a torque wrench or a tension gauge, assembled according to the standards specified for the battery module 1000. After the battery module 1000 is locked, the output values ​​of the pressure sensors integrated at each location point are read by a data acquisition device. Real-time pressure data at each location point within the battery module 1000 along the length direction of the battery module 1000, for example, from the first end plate 200 to the second end plate 300, are recorded.

[0048] Using data processing software such as MATLAB, Python, or Origin, the location of each standard buffer pad is plotted on the x-axis, and the pressure value collected at each location is plotted on the y-axis. Curve fitting or interpolation is performed on the discrete pressure data points to generate a continuous pressure distribution curve. This curve represents the pressure distribution data along the length of the battery module 1000, visually reflecting the pressure change trend within the battery module 1000.

[0049] Specifically, pressure distribution data along the length of the battery module 1000 can be obtained through simulation, including: setting standard buffer pads between the battery cells 100, between the battery cell 100 and the first end plate 200, and between the battery cell 100 and the second end plate 300; establishing a simulation model of the battery module 1000; applying preload to the first end plate 200 and the second end plate 300; calculating and extracting the contact pressure of each standard buffer pad; and fitting the contact pressure of each standard buffer pad to obtain pressure distribution data.

[0050] In 3D modeling software such as CATIA and SolidWorks, a full geometric model of the battery module 1000 is created. Virtual standard buffer models with consistent geometry and physical properties are created between each adjacent cell 100, between cell 100 and the first end plate 200, and between cell 100 and the second end plate 300, ensuring their positions correspond to the actual design. The geometric model is imported into pre-processing software such as Ansa and Hypermesh to mesh the first end plate 200, second end plate 300, cell 100, and buffer pads. Appropriate material properties are assigned to each component, and contact relationships, such as frictional contact and bonded contact, are defined between cell 100 and the standard buffer pad, between the standard buffer pad and the first end plate 200, and between the standard buffer pad and the second end plate 300. Constraints simulating actual working conditions are applied to the first end plate 200 and the second end plate 300, such as displacement boundary conditions, to simulate the compression state after tightening the nuts. The contact pressure values ​​on the surface of each virtual standard buffer pad model were calculated and extracted one by one. The extracted contact pressure values ​​were plotted on the x-axis using the position coordinates of the standard buffer pad along the 1000mm length of the battery module, and the extracted values ​​on the y-axis. The discrete data points were imported into data processing software to generate a continuous curve reflecting the pressure distribution trend within the module, thus obtaining the pressure distribution data.

[0051] Specifically, the step S104 of determining the thickness of each elastic buffer pad 400 in the free state based on the pressure compensation value includes: determining the reference thickness based on the standard buffer pad; determining the target compression amount based on the pressure compensation value, wherein the target compression amount is positive when the pressure compensation value is greater than 0 and negative when the pressure compensation value is less than 0; and determining the thickness of each elastic buffer pad 400 in the free state based on the reference thickness and the target compression amount.

[0052] When determining the thickness of each elastic buffer pad 400, the thickness of the standard buffer pad is used as the reference thickness. The target compression amount refers to the compression deformation converted from the pressure compensation value at the location of the elastic buffer pad 400, that is, the distance the elastic buffer pad 400 needs to be pressed down more or less to achieve the reference pressure. When the pressure compensation value is greater than 0, it indicates that the pressure at the current location is insufficient and the support force needs to be increased. In this case, an additional thickness is added to the thickness of the standard buffer pad to obtain the thickness of the elastic buffer pad 400 to be placed at the corresponding location, that is, the target compression amount is positive; when the pressure compensation value is less than 0, it indicates that the pressure at the current location is too high and the support force needs to be reduced. In this case, an additional thickness is subtracted from the thickness of the standard buffer pad to obtain the thickness of the elastic buffer pad 400 to be placed at the corresponding location, that is, the target compression amount is negative. After the above addition and subtraction calculations, the specific thickness value of the elastic buffer pad 400 to be placed at each position along the length of the battery module 1000 in the free state is obtained.

[0053] Based on the thickness of a standard buffer pad, and combined with the pressure compensation values ​​at various locations within the battery module 1000, the thickness of the elastic buffer pad 400 at each location is determined. Users only need to decide whether to increase or decrease the thickness based on the sign of the pressure compensation value, reducing the complexity of extreme logic. For locations with small adjustment ranges, it can even be achieved by stacking thin sheets or grinding standard parts, without needing to create entirely new injection molds. Especially in areas where the pressure compensation value approaches 0, a general-purpose standard buffer pad can be used directly, without customization. This significantly reduces the number of molds and the complexity of material management.

[0054] In some feasible implementations, the target compression amount is determined based on the pressure compensation value, including: obtaining the stress-strain curve of the elastic buffer pad 400 material; and converting the pressure compensation values ​​at each position between adjacent cells 100, between cell 100 and the first end plate 200, and between cell 100 and the second end plate 300 into the target compression amount.

[0055] Mechanical property tests were conducted on the selected elastic cushioning pad material 400. Stress values ​​were recorded under different compression ratios, and stress-strain curves were plotted. Based on the stress-strain curves, the strain value corresponding to each pressure compensation value was found, i.e., the compression deformation ratio of the elastic cushioning pad 400. The strain values ​​were converted to linear dimensions using the following formula:

[0056] In the formula, H0 represents the target compression amount of the elastic cushioning pad at each location, and H0 represents the reference thickness of the standard cushioning pad. This represents the compression deformation ratio corresponding to each pressure compensation value.

[0057] For the under-voltage area within the battery module 1000, i.e. the area at both ends of the battery module 1000, the pressure compensation value is positive, requiring higher support force. Therefore, a thicker elastic buffer pad 400 is needed to generate a larger compression amount to provide support force. For the over-voltage area within the battery module 1000, i.e. the area in the middle of the battery module 1000, the pressure compensation value is negative, requiring weaker support force. Therefore, a thinner elastic buffer pad 400 is needed to generate a smaller compression amount.

[0058] By directly using the material's stress-strain curve for conversion, this method fully considers the changes in the material's mechanical properties at different compression stages. This allows the calculated thickness of the elastic buffer pad 400 in its free state to accurately generate the preset pressure rebound force after assembly, ensuring that the pressure finally applied to the battery cell 100 is consistent with the reference pressure, significantly reducing errors and thus improving the uniformity of pressure distribution within the battery module 1000. Furthermore, through precise calculation of the target compression amount, the designed thickness of the elastic buffer pad 400 in its free state can better match the assembly space of the battery module 1000. This means that when the end plate is locked, all the elastic buffer pads 400 can simultaneously reach the designed compression state, ensuring both preload and avoiding assembly difficulties or structural damage caused by dimensional chain errors.

[0059] In some feasible implementations, the method further includes: obtaining the total length of the battery module 1000; obtaining the tolerances between the cells 100, between the cells 100 and the first end plate 200, and between the cells 100 and the second end plate 300; and obtaining the thickness of the elastic buffer pad 400 corresponding to each standard buffer pad in the free state based on the total length, tolerances, and target compression amount.

[0060] The distance between the inner sides of the first end plate 200 and the second end plate 300 of the battery module 1000 is measured to determine the total length of the battery module 1000. The overall tolerance is obtained by statistically analyzing the dimensional tolerances in the width direction of the individual battery cells 100, the cumulative tolerances after stacking multiple battery cells 100, the thickness and flatness tolerances of the first end plate 200 and the second end plate 300, and the thickness tolerance of the standard buffer pad itself. For example, the battery module 1000 has N battery cells 100 and N+1 elastic buffer pad positions. The total length of the battery module 1000 after assembly is the width of N battery cells 100 and the compressed thickness of N+1 buffer pads. The formula for calculating the compressed thickness of the elastic buffer pad at each specific location is:

[0061] In the calculation formula, Hw is the thickness of the elastic buffer pad 400 after compression at a specific location, and Lt is the total length of the battery module 1000 after assembly. Let N be the total length of the battery cells. The quantity is 400 for the elastic cushioning pad. This is a tolerance adjustment item used to compensate for dimensional deviations of the elastic buffer pad at specific locations, ensuring the overall fit of the elastic buffer pad. Based on the target compression amount, the thickness of the elastic buffer pad 400 in its free state is the sum of the compressed thickness of the elastic buffer pad 400 and the corresponding target compression amount.

[0062] By introducing the total length as a strong constraint, this method ensures that the sum of the thicknesses of all elastic buffer pads 400 in their free state, plus the total length of the battery cell 100, is exactly equal to or slightly greater than the total length of the battery module 1000. This guarantees that the battery module 1000 can be assembled smoothly and with precise dimensions. Based on the tolerance distribution within the battery module 1000, the thickness of the buffer pads at specific locations within the battery module 1000 is fine-tuned, significantly improving the success rate and yield of assembly. The manufacturing method for the battery module 1000 provided in this application, while meeting the target compression amount and ensuring uniform pressure within the battery module 1000, also guarantees the assemblability of the battery module 1000. This allows the designed buffer pads to not only solve the problem of uneven stress on the battery cell 100 but also better fit the actual assembly space, avoiding rework and repairs.

[0063] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0064] Furthermore, the use of terms such as "first," "second," etc., in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0065] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0066] Furthermore, the technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application.

[0067] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery module, characterized in that, include: Multiple battery cells, which are arranged sequentially along the length of the battery module; A first end plate and a second end plate are respectively disposed at both ends of the plurality of battery cells along the length direction of the battery module; Multiple elastic buffer pads are respectively located between the battery cell and the first end plate, between the battery cell and the second end plate, and between adjacent battery cells. Among the multiple elastic buffer pads, the effective thickness of the elastic buffer pads located between adjacent battery cells is less than the effective thickness of the elastic buffer pads located between the battery cell and the first end plate, and the effective thickness of the elastic buffer pads located between adjacent battery cells is less than the effective thickness of the elastic buffer pads located between the battery cell and the second end plate.

2. The battery module as described in claim 1, characterized in that, The plurality of elastic buffer pads are arranged sequentially at intervals along the length of the battery module, and the thickness of the plurality of elastic buffer pads gradually decreases from both ends toward the middle.

3. The battery module as described in claim 1, characterized in that, The plurality of elastic buffer pads include a plurality of buffer pad groups, which are arranged sequentially at intervals along the length of the battery module. Each buffer pad group includes at least two adjacent elastic buffer pads. The elastic buffer pads in each buffer pad group have the same thickness, and the thickness of the plurality of buffer pad groups gradually decreases from both ends of the plurality of buffer pad groups toward the middle.

4. The battery module as described in any one of claims 1-3, characterized in that, The elastic cushioning pad is made of at least one of foam, silicone, or rubber.

5. A method for manufacturing a battery module, characterized in that, The battery module includes multiple battery cells, multiple elastic buffer pads, a first end plate and a second end plate. The first end plate and the second end plate are respectively located at both ends of the multiple battery cells along the length direction of the battery module. The multiple elastic buffer pads are respectively located between the battery cells and the first end plate, between the battery cells and the second end plate, and between adjacent battery cells. The method includes: Set the reference pressure; Obtain the pressure distribution data of the battery module along its length; The pressure compensation values ​​between adjacent cells, between a cell and the first end plate, and between a cell and the second end plate are determined based on the reference pressure and the pressure distribution data. The thickness of each elastic buffer pad in its free state is determined based on the pressure compensation value. The larger the pressure compensation value, the larger the thickness of the elastic buffer pad; the smaller the pressure compensation value, the smaller the thickness of the elastic buffer pad.

6. The manufacturing method as described in claim 5, characterized in that, The step of obtaining the pressure distribution data of the battery module along its length includes: Standard buffer pads are provided between the cells of the battery module, between the cells and the first end plate, and between the cells and the second end plate; Lock the first end plate and the second end plate; Collect the pressure values ​​of each standard buffer pad; By fitting the pressure values ​​of each standard buffer pad, the pressure distribution data of the battery module along its length can be obtained.

7. The manufacturing method as described in claim 5, characterized in that, The step of obtaining the pressure distribution data of the battery module along its length includes: Standard buffer pads are provided between the cells of the battery module, between the cells and the first end plate, and between the cells and the second end plate; Establish a simulation model of the battery module; Apply a preload to the first end plate and the second end plate; Calculate and extract the contact pressure for each of the standard cushioning pads; The pressure distribution data is obtained by fitting the contact pressure of each of the standard cushioning pads.

8. The manufacturing method as described in claim 6 or 7, characterized in that, Determining the thickness of the elastic buffer pads at various locations within the battery module based on the pressure compensation value includes: Determine the reference thickness based on the standard cushioning pad; The target compression is determined based on the pressure compensation value. When the pressure compensation value is greater than 0, the target compression is positive; when the pressure compensation value is less than 0, the target compression is negative. The thickness of the elastic buffer pad at each location within the battery module is determined based on the reference thickness and the target compression amount.

9. The manufacturing method as described in claim 8, characterized in that, Determining the target compression amount based on the pressure compensation value includes: Obtain the stress-strain curve of the elastic buffer pad material; The pressure compensation values ​​at each location between adjacent cells, between a cell and the first end plate, and between a cell and the second end plate are converted into target compression values.

10. The manufacturing method as described in claim 9, characterized in that, The method further includes: Obtain the total length of the battery module; Obtain the tolerances between the battery cells, between the battery cell and the first end plate, and between the battery cell and the second end plate; The thickness of each elastic buffer pad in its free state is obtained based on the total length, the tolerance, and the target compression.

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