A battery module and a battery pack

Abstract

The utility model provides a kind of battery module and battery pack, battery module includes: multiple battery monomers, battery monomer includes shell and electrode assembly being set in shell, shell includes shell, shell is at least one end opening structure formed by bending from metal plate, shell includes two first side walls oppositely arranged along first direction, and two second side walls oppositely arranged along second direction, first direction is perpendicular to second direction, at least one second side wall is formed with the first welding layer distributed along third direction, third direction is perpendicular to first direction and second direction;Multiple battery monomers are arranged along first direction;Buffering member that can be elastically deformed is filled between the first side wall of at least two battery monomers, and the setting position of above-mentioned first welding layer cooperates the arrangement mode of multiple battery monomers, and buffering member is filled between first side wall, the structural strength of battery module can be effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery module and a battery pack. Background Technology

[0002] A battery module is assembled from multiple battery cells connected in series and parallel to provide electrical equipment with larger capacity and higher voltage power. In order to meet the power requirements of the battery module, the production activities now tend to use battery cells with larger profiles. If the structural strength of the battery module cannot meet the requirements, it will lead to the battery module not working reliably and safely. Therefore, how to improve the structural strength of the battery module is a technical problem that urgently needs to be solved in battery technology. Utility Model Content

[0003] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a battery module with reliable structural strength.

[0004] This utility model also provides a battery pack.

[0005] The battery module provided in the first aspect of this utility model includes: a plurality of battery cells, each battery cell including a housing and an electrode assembly disposed in the housing, the housing including a shell, the shell being a structure formed by bending a metal plate with at least one open end, the shell including two first sidewalls disposed opposite to each other along a first direction and two second sidewalls disposed opposite to each other along a second direction, the first direction being perpendicular to the second direction, at least one of the second sidewalls having a first welding layer distributed along a third direction, the third direction being perpendicular to the first direction and the second direction;

[0006] Multiple battery cells are arranged along a first direction;

[0007] At least two of the battery cells are filled with a cushioning element that can undergo elastic deformation between their first sidewalls.

[0008] In one embodiment of the present invention, the width of the first sidewall in the second direction is greater than the width of the second sidewall in the first direction, and the larger surface of the electrode assembly faces the first sidewall.

[0009] In one embodiment of the present invention, the distance between the first weld layer and one of the first sidewalls in the first direction is 1 / 5 to 1 / 3 of the width of the second sidewall in the first direction.

[0010] In one embodiment of the present invention, the distance between the first weld layer and one of the first sidewalls in the first direction is 6 / 25 to 13 / 50 of the width of the second sidewall in the first direction.

[0011] In one embodiment of the present invention, the electrode assembly includes a plurality of cores stacked along the first direction. Each core includes two straight portions disposed opposite to each other along the first direction and two arc portions disposed opposite to each other along the second direction. Each arc portion has an arc-shaped apex protruding outward in the second direction. The first welding layer is disposed away from the arc-shaped apex in the first direction.

[0012] In one embodiment of the present invention, the electrode assembly includes four cores stacked along the first direction, and the first welding layer is located between the core closest to the first sidewall and the arc-shaped tip of the core adjacent to it.

[0013] In one embodiment of the present invention, the outer side of the housing is wrapped with an insulating film. The insulating film is joined at positions corresponding to at least a portion of the first welding layer to form an overlapping area distributed along the third direction. Alternatively, the insulating film has a hollowed-out area at positions corresponding to at least a portion of the first welding layer to expose at least a portion of the first welding layer. The battery module also includes a frame for fixing and supporting multiple battery cells. The hollowed-out area is bonded to the side wall of the frame or the inner bottom surface of the frame by an adhesive.

[0014] In one embodiment of the present invention, the outer shell further includes a bottom plate, the bottom plate covering at least one opening of the shell, and a second welding layer is formed on the side of the bottom plate away from the shell, the second welding layer connecting the bottom plate and the opening to seal the opening.

[0015] In one embodiment of the present invention, the battery module further includes a frame for fixing and supporting multiple battery cells, the bottom surface of the base plate and the inner bottom surface of the frame are bonded together by an adhesive, and at least a portion of the second welding layer is embedded in the adhesive.

[0016] Compared with the prior art, the battery module provided by this utility model has at least the following beneficial effects: the first welding layer is formed on the second sidewall, and multiple battery cells are arranged along the first direction. The above structural design and arrangement can convert the extrusion force generated by the multiple battery cells in the first direction during assembly into a compressive force applied to the tangential direction of the first welding layer. Since the first welding layer is a splicing welding layer with tensile strength higher than shear strength, it is equivalent to enhancing the structural strength of the battery module compared with the extrusion force being equivalent to the shear force applied to the normal direction of the first welding layer when the first welding layer is formed on the first sidewall. Secondly, the buffer that can undergo elastic deformation is filled between the first sidewalls, which can effectively absorb part of the force between the first sidewalls when the battery module is assembled and when it is subjected to impact and vibration on the electrical equipment, and also reduce the force on the first welding layer, thereby further enhancing the structural strength of the battery module.

[0017] The larger surface of the electrode assembly faces the first sidewall, and the first welding layer is formed on the second sidewall, which has a smaller width. This reduces the deformation of the first welding layer. Setting the distance between the first welding layer and the first sidewall to 1 / 5 to 1 / 3 or 6 / 25 to 13 / 50 of the width of the second sidewall further ensures that the stress value at the first welding layer is within a smaller force value range, thereby further ensuring the structural strength of the battery cell and battery module.

[0018] The battery pack provided in the second aspect of this utility model includes a plurality of battery modules as described in any of the first aspects.

[0019] Because the battery pack uses a first welding layer formed on the second sidewall, and multiple battery cells are arranged along the first direction to form a battery module with higher structural strength, the battery pack also has higher structural strength. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0021] In the attached diagram:

[0022] Figure 1 This is a partial structural unfolded view of a battery module provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of a portion of the battery cells provided in one embodiment of the present invention along a third direction;

[0024] Figure 3 for Figure 2 A magnified view of part A;

[0025] Figure 4 This is a schematic diagram of the structure of some battery cells along a third direction provided in another embodiment of the present invention;

[0026] Figure 5 This is an axonometric view of a battery cell provided in one embodiment of the present invention;

[0027] Figure 6 This is an axonometric view of a battery cell provided in one embodiment of the present invention;

[0028] Figure 7 This is an axonometric view of a battery cell provided in another embodiment of the present invention;

[0029] Figure 8 This is a partial structural unfolded view of a battery module provided in another embodiment of the present invention;

[0030] Figure 9 This is a cross-sectional view of a partial battery module including a partial frame and battery cells, provided according to an embodiment of the present invention.

[0031] Figure 10 for Figure 9 A magnified view of a portion of part B.

[0032] Figure 11 The graph is a plot of stress and other data obtained from simulation of a shell with dimensions of 74.8 mm, 319.141 mm, and 238.7 mm in the first, second, and third directions, respectively.

[0033] Figure 12 The graph is a plot of stress and other data obtained from simulation of a shell with dimensions of 56.8 mm, 319.141 mm, and 238.7 mm in the first, second, and third directions, respectively.

[0034] Figure 13 The graph is a plot of stress and other data obtained from simulation of a shell with dimensions of 74.8 mm, 499.14 mm, and 238.7 mm in the first, second, and third directions, respectively.

[0035] Figure 14 The graphs are plotted using stress and other data obtained from simulations of shells with dimensions of 99.8 mm, 499.14 mm, and 300 mm in the first, second, and third directions, respectively.

[0036] The markings are as follows:

[0037] 100. Battery cell; 110. Casing; 111. First sidewall; 112. Second sidewall; 113. First welded layer; 120. Base plate; 121. Second welded layer; 130. Core; 131. Arc portion; 1311. Arc tip; 140. Insulating film; 141. Overlapping area; 142. Hollowed-out area; 200. Buffer; 300. Heat insulation pad; 400. Inner bottom surface of frame; X. First direction; Y. Second direction; Z. Third direction. Detailed Implementation

[0038] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0039] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0040] To provide electrical energy that meets certain current and voltage specifications for devices such as automobiles and computers, multiple battery cells need to be assembled into battery modules through series and parallel connections. In current production activities, battery cells are increasingly trending towards large-scale designs. To manufacture the casings of these large-scale battery cells, the processing method has shifted from traditional stretching and stamping to bending and welding metal sheets. However, the latter method produces weld seams. Since the strength of the weld layer is lower than that of the base material, the strength of the casing is affected, and consequently, the strength of the battery module assembled from the battery cells is also affected. This invention mitigates the negative impact of the weld layer on the structural strength of the battery module by limiting the arrangement of the weld layer on the casing and the battery cells within the battery module, and by placing buffer components between adjacent sidewalls of the battery cells. The specific implementation method is as follows:

[0041] This utility model provides a battery module, please refer to [link / reference]. Figures 1-10The system includes: multiple battery cells 100, each battery cell 100 including a housing and an electrode assembly disposed within the housing. The housing includes a shell 110, which is a structure formed by bending a metal plate to create an opening at at least one end. In a specific embodiment, the metal plate can be an aluminum alloy plate or a stainless steel plate. Aluminum alloy plates have better ductility and lighter weight, while stainless steel plates have higher strength. The shell 110 includes two first sidewalls 111 disposed opposite each other along a first direction X, and two second sidewalls 112 disposed opposite each other along a second direction Y. The first direction X is perpendicular to the second direction Y. At least one of the second sidewalls 112 has a first welding layer 113 distributed along a third direction Z, which is perpendicular to the first direction X and the second direction Y. In a specific embodiment, only one metal plate can be bent multiple times to form a splice part on one of the second sidewalls 112, and then the splice part can be welded. In this case, only... Figure 2 As shown, a first weld layer 113 is formed on one of the second sidewalls 112. Alternatively, two metal plates can be bent once, forming splice portions on both of the second sidewalls 112, and then the splice portions are welded together. In this case, it will look like... Figure 4 As shown, a first weld layer 113 is formed on both second sidewalls 112. In a specific embodiment, to ensure the strength and smoothness of the weld layer, a high-energy-density laser welding method can be used. Multiple battery cells 100 are arranged along the first direction X. At least two battery cells 100 have an elastically deformable buffer 200 between their first sidewalls 111. In a specific embodiment, a rubber-based material or silicone material that simultaneously possesses flame retardancy and good elasticity can be used, or other materials such as... Figure 1 , Figure 7 The elastic element is made into a U-shaped structure with an area equivalent to that of the first sidewall 111, and the U-shaped gap is filled with a heat insulation pad 300 in a combined structure. In addition, in a specific embodiment, in order to enhance the buffering effect of the buffer element 200, the buffer element 200 can be filled between the first sidewalls 111 of each adjacent battery cell 100.

[0042] First, during assembly, multiple battery cells 100 are typically sandwiched between two end plates along the first direction X. This results in a compressive force along the first direction X between adjacent first sidewalls 111 of the multiple battery cells 100. Since the first weld layer 113 is formed on the second sidewall 112, this compressive force is equivalent to a tangential compressive force applied to the first weld layer 113. If the first weld layer 113 were formed on the first sidewall 111, the compressive force would be equivalent to a force applied to the first weld layer 113 in the normal direction. The shear force is absorbed by the first weld layer 113, which is a splicing weld layer with tensile strength higher than shear strength. Therefore, the arrangement of the battery cells 100 is equivalent to enhancing the structural strength of the battery module. Secondly, the buffer 200 that can undergo elastic deformation is filled between the first sidewalls 111, which can effectively absorb part of the force between the first sidewalls 111 when the battery module is assembled and used on electrical equipment and subjected to impact and vibration. It also reduces the force on the first weld layer 113, thereby further enhancing the structural strength of the battery module.

[0043] Please see Figure 2 , Figure 4 In one embodiment of this utility model, the width of the first sidewall 111 in the second direction Y is greater than the width of the second sidewall 112 in the first direction X. The large surface of the electrode assembly faces the first sidewall 111. That is, the first sidewall 111 can be understood as the large surface of the shell 110 and the second sidewall 112 as the small surface of the shell 110. Since the width of the first sidewall 111 is greater than the width of the second sidewall 112, the large surface of the electrode assembly is arranged facing the first direction X. The large surface of the electrode assembly is more prone to expansion. Therefore, the deformation of the shell 110 on the first sidewall 111 will be greater than the deformation on the second sidewall 112. Therefore, the first welding layer 113 is set on the second sidewall 112 to minimize the deformation at the first welding layer 113, thereby further ensuring the structural strength of the shell 110 and thus further ensuring the structural strength of the battery module.

[0044] In one embodiment of this utility model, please refer to Figures 2-4 The distance D between the first weld layer 113 and one of the first sidewalls 111 in the first direction X is 1 / 5 to 1 / 3 of the width C of the second sidewall 112 in the first direction X.

[0045] Please see Figure 1As shown, the first direction X, the second direction Y, and the third direction Z can be understood as the width direction, length direction, and height direction of the shell 110, respectively. The edge of the shell 110, i.e., the junction of the first sidewall 111 and the second sidewall 112, is a stress concentration point where the geometric shape changes abruptly. Therefore, the first weld layer 113 should avoid this area by a certain distance. That is, the width of the first weld layer 113 in the first direction X should have an appropriate lower limit. The above is a qualitative analysis. In order to obtain a more specific and accurate formation position of the first weld layer 113, the following will be deduced and analyzed in combination with specific simulation experimental data.

[0046] Table 1 shows the simulation data obtained from the simulation experiment of the casing 110 of a battery cell with dimensions of 319.141 mm (length), 74.8 mm (width), and 238.7 mm (height). Specifically, the length of the casing 110 in the first direction X is 74.8 mm. As shown in the first column of Table 1, seven sets of values ​​were selected, ranging from 5.6 mm to 37.4 mm, representing the distance between the first welding layer 113 and the first sidewall 111 in the first direction X (hereinafter referred to as the position of the first welding layer 113). These distance values ​​were then converted into percentages of the length of the casing 110 in the first direction X, resulting in Table 1. The data in the second column, ranging from 7.49% to 50%, were used to obtain stress under different working conditions. The following constraints were set in the simulation software: a negative pressure of 0.1 MPa inside the shell 110, a low-pressure working condition where the shell 110 is filled with air to a pressure of 1.1 MPa, and a free expansion working condition where the expansion rate of the electrode assembly is set to 6%. The stress values ​​of the first weld layer shown in the third, fourth, and fifth columns of Table 1 were obtained respectively. For example, when the distance of the first weld layer 113 is 5.6 mm as shown in the first row, the stress at the first weld layer 113 under the negative pressure working condition is 7 MPa as shown in the third column of the first row.

[0047] Table 1

[0048]

[0049] Find the maximum stress value under each working condition. Using this maximum stress value as the standard, calculate the percentage difference between other stress values ​​under this working condition and the maximum stress value. This percentage difference is the stress optimization ratio shown in the third, fourth, and fifth columns of Table 2. Taking the negative pressure working condition as an example, the data in the third column of Table 1 shows that when the position of the first weld layer 113 is 37.4 mm, the length ratio of the first weld layer 110 to the shell 110 in the first direction X is 50%, and the stress value reaches the maximum value of 108.8 MPa. When the position of the first weld layer 113 is 14.4 mm, the stress value is 46.9 MPa, and the percentage of the maximum stress value of 108.8 MPa is 43.11%. That is, compared with the maximum stress value, the stress value is optimized by 56.89% as shown in the second row and third column of Table 2. Similarly, the optimization ratio of the first weld layer 113 in other positions and working conditions can be obtained.

[0050] Table 2

[0051]

[0052] Further normalization processing is performed on the above optimization ratios, that is, the largest optimization ratio is used as the standard, and the optimization ratios at other positions of the first weld layer 113 are calculated and their ratios are calculated. For example, under negative pressure conditions, the largest optimization ratio is 93.57% of the first weld layer 113 at a distance of 5.6 mm. Using this value as the standard value of 100%, the optimization ratio at a distance of 14.4 mm of the first weld layer 113 is 56.89%, and the ratio of 93.57% is 60.81%. Therefore, the normalized optimization ratio here is 60.81% as shown in the second row and third column of Table 3. Similarly, the normalized optimization ratios of the first weld layer 113 at other distances and conditions shown in Table 3 are obtained.

[0053] Table 3

[0054]

[0055] To make a more intuitive comparison, the normalized optimization ratio is used as the vertical axis, and the position of the first weld layer 113 is used as the horizontal axis, resulting in the following: Figure 11 As shown in the graph, it can be observed that under negative pressure and inflation conditions, the normalized optimization result of the stress value is negatively correlated with the position of the first weld layer 113, that is, the smaller the position of the first weld layer 113, the better the optimization result. Under free expansion conditions, except for the initial distance of 5.6 mm, the normalized optimization results are positively correlated with the position of the first weld layer 113. That is, the larger the position of the first weld layer 113, the better the optimization results. Plotting a horizontal target line with a vertical axis of 10% on the graph shows that the curves under all three conditions are above the horizontal axis value of this target line. This means that the ratio of the position of the first weld layer 113 to the length of the shell 110 in the first direction X is between 21% and 36%. In other words, when the position of the first weld layer 113 is within the above range, the normalized optimization ratio of the stress value at the first weld layer can be guaranteed to be above 10% under any condition. This means that the stress value at the first weld layer achieves a relatively ideal small value. Similarly, when plotting a horizontal target line with a vertical axis of 20% on the graph, the ratio of the position of the first weld layer 113 to the length of the shell 110 in the first direction X is between 24% and 32%.

[0056] In addition, a fixed value comparison analysis can also be performed. For example, if the first weld layer 113 is located at the middle position of the shell 110 in the first direction X and the position of the first weld layer 113 is 14.4 mm away, the stress values ​​of the first weld layer 113 at the above two distances are 108.8 MPa and 46.9 MPa, respectively. The latter is 56.9% less than the former. Under the inflation condition, the stress values ​​of the first weld layer 113 are 135.2 MPa and 82.5 MPa, respectively. The latter is 38.98% less than the former. Furthermore, the simulation data shows that the maximum equivalent plastic deformation of the former is 25.78%, and the maximum equivalent plastic deformation of the latter is 25.81%. The difference between the two is small. Under free expansion conditions, the stress values ​​at the first weld layer 113 are 99.7 MPa and 116.7 MPa, respectively. The latter is 17.1% higher than the former. Since free expansion conditions are relatively rare in practical applications, the difference between the two under constrained expansion conditions should be less than 17%. That is, when the first weld layer 113 is in the offset position, compared with the position in the middle, although the stress value at the first weld layer 113 under free expansion conditions will increase slightly, it can significantly reduce the stress value at the first weld layer 113 under negative pressure and inflation conditions.

[0057] Similarly, Table 4 below shows the data obtained from simulation experiments on a smaller-sized shell 110 with dimensions of 319.141 mm, 56.08 mm, and 152.987 mm. Eleven groups of relatively evenly spaced first weld layer 113 positions were selected, and the stress values ​​of the first weld layer 113 at different distances were obtained under two working conditions: negative pressure and free expansion.

[0058] Table 4

[0059]

[0060] Table 5 below shows the stress optimization ratio and normalized optimization ratio obtained after processing the stress values ​​in the above table.

[0061] Table 5

[0062]

[0063] Figure 12The normalized optimization result curve obtained using the data in the table above shows that when the target line is 10%, the curves under both working conditions are above the target line, meaning the ratio of the length of the first weld layer 113 to the length of the shell 110 in the first direction X is between 11% and 42%. When the target line is set to 20%, the curves under both working conditions are above the target line, meaning the ratio of the length of the first weld layer 113 to the length of the shell 110 in the first direction X is between 12% and 38%.

[0064] Table 6 below shows the stress data of the first weld layer 113 at different locations obtained after simulation analysis of the shell 110 with dimensions of 74.8 mm, 499.14 mm and 238.7 mm in the first direction X, the second direction Y and the third direction Z respectively under negative pressure and expansion conditions.

[0065] Table 6

[0066]

[0067] Table 7 below shows the stress optimization ratio and normalized optimization ratio obtained after further processing of the stress data in Table 6 above.

[0068] Table 7

[0069]

[0070] Figure 13 The normalized optimization result curve obtained using the data in the table above shows that when the target line is set at 10%, the curves under both negative pressure and expansion conditions are above the target line, meaning the ratio of the length of the first weld layer 113 to the length of the shell 110 in the first direction X is between 10% and 38%. When the target line is set at 20%, the curves under both negative pressure and expansion conditions are above the target line, meaning the ratio of the length of the first weld layer 113 to the length of the shell 110 in the first direction X is between 12% and 33%.

[0071] Table 8 below shows the stress data of the first weld layer 113 at different locations obtained after simulation analysis of the shell 110 with larger dimensions of 99.8 mm, 499.14 mm and 300 mm in the first direction X, the second direction Y and the third direction Z respectively under negative pressure and expansion conditions.

[0072] Table 8

[0073]

[0074] Table 9 below shows the stress optimization ratio and normalized optimization ratio obtained after further processing of the stress data in Table 8 above.

[0075] Table 9

[0076]

[0077] Figure 14 The graph is a curve plotted using the normalized optimization ratio data obtained from Table 9 above. As can be seen from the graph, when the target line is set to 10%, the curves under both negative pressure and expansion conditions are located above the target line on the horizontal axis, that is, the ratio of the length of the first weld layer 113 to the length of the shell 110 in the first direction X is between 8% and 31%. When the target line is set to 20%, the curves under both conditions are located above the target line on the horizontal axis, between 12% and 26%.

[0078] From the simulation experimental data and graphical analysis of the above four different sizes of shell 110, it can be concluded that when the target line of the normalized optimization ratio is set to 10%, the ratio of the position of the first weld layer 113 to the length of the shell 110 in the first direction X falls between 21% and 36%, 11% and 42%, 10% and 38%, and 8% and 31%, respectively, and their intersection range is 21% to 31%. Considering that it is convenient to perform operations such as marking and positioning when cutting, bending and splicing metal plates in actual production and processing, the ratio of the position of the first weld layer 113 to the length of the shell 110 in the first direction X is taken as 1 / 5 to 1 / 3. Within this position range, the stress value at the first weld layer 113 can achieve a relatively ideal small value.

[0079] By offsetting the first welding layer 113 to the second wall surface of the housing 110, i.e. the side with a smaller area of ​​the housing 110, with the offset distance being 1 / 5 to 1 / 3 of the width in the first direction X, i.e. the width of the housing 110, the stress on the first welding layer 113 is effectively reduced, and the overall strength of the spliced ​​housing 110 is significantly improved. During the use of the battery cell, this effectively reduces or prevents accidents such as electrolyte leakage caused by easy cracking at the welding joint of the housing or insufficient sealing. Since the stress on the first welding layer is small, the housing 110 is also less prone to damage, thus having a longer service life. At the same time, since there are no limitations on the tonnage and stroke of the stretching equipment, it can be formed simply by bending and welding the metal plate. Therefore, the above-mentioned splicing and welding method of the housing 110 is also convenient for mass production of large-profile battery cell housings 110.

[0080] Battery modules assembled from battery cells using the above structural design also have the advantages of higher structural strength, longer service life, and easier mass production.

[0081] In one embodiment of the present invention, in order to minimize the stress at the first weld layer 113, the target line for the normalized optimization ratio is set to 20%. The ratio of the position of the first weld layer 113 to the length of the shell 110 in the first direction X falls between 24% and 32%, 12% and 38%, 12% and 33%, and 12% and 26%, respectively, and their intersection range is 24% to 26%. That is, when the distance between the first weld layer 113 and one of the first sidewalls 111 in the first direction X is 6 / 25 to 13 / 50 of the width of the second sidewall 112 in the first direction X, it can be ensured that the stress at the first weld layer 221 is smaller, thereby giving the shell 200 higher strength.

[0082] In one embodiment of this utility model, please refer to Figures 2-4 The electrode assembly includes a plurality of cores 130 stacked along a first direction X. Each core 130 includes two straight portions arranged opposite each other along the first direction X and two arc portions 131 arranged opposite each other along a second direction Y. The arc portions 110 have arc-shaped apex 1311 protruding outward in the second direction Y. The first welding layer 113 is away from the arc-shaped apex 1311 in the first direction X. The above arrangement can effectively prevent the first welding layer 113 from piercing the separator of the core 130 at the excess height protrusion towards the inner cavity of the housing 110, thereby preventing accidents such as lithium plating of the separator or short circuit between the positive and negative electrode sheets, thus improving the working reliability and safety of the battery cell 100 and the battery module assembled therefrom.

[0083] In one embodiment of this utility model, please refer to Figures 2-4 The electrode assembly includes four cores 130 stacked along the first direction X. The first welding layer 113 is located between the core 130 closest to the first sidewall 111 and the arc apex 1311 of the adjacent core 130, so as to ensure the strength of the housing 110 and the working reliability of the cores 130, thereby also ensuring the strength and working reliability of the battery module assembled from the battery cells 100.

[0084] In one embodiment of this utility model, please refer to Figure 5 The outer side of the housing 110 is wrapped with an insulating film 140. In a specific embodiment, the insulating film 140 can be made of PET polyester or polyimide PI blue film with high insulation performance, so as to provide physical isolation, insulation, flame retardant heat dissipation and other functions for the battery cell 100. The insulating film 140 is joined with at least a portion of the first welding layer 113 to form an overlapping area 141 distributed along the third direction Z. Since the overlapping area 141 increases the thickness of the insulating film 140, it can reduce the risk of the protrusion of the first welding layer puncturing the insulating film 140, thereby enhancing the working reliability of the battery cell 100 and the battery module.

[0085] In one embodiment of this utility model, please refer to Figure 6 The battery module also includes a frame for fixing and supporting multiple battery cells 100. An insulating film 140 is wrapped around the outside of the housing 110. A cutout area 142 is formed at a position corresponding to at least a portion of the first welding layer 113, exposing at least a portion of the first welding layer 113. The cutout area 142 is bonded to the side wall of the frame or the inner bottom surface 400 of the frame by an adhesive. In a specific embodiment, the adhesive can be a structural adhesive with high strength and good thermal conductivity. Figure 1 When the hollow area 142 shown is bonded to the side wall of the frame using adhesive, the adhesive can suppress and constrain the deformation of the first welded layer 113, thereby effectively ensuring the strength of the first welded layer 113. Please refer to [link / reference needed]. Figure 7 When the hollow area 142 is bonded to the inner bottom surface 400 of the frame with structural adhesive, in addition to the structural adhesive restraining and suppressing the deformation of the first welding layer 113, the weight of the battery cell 100 itself can further suppress the deformation of the first welding layer 113, thereby more effectively ensuring the strength of the first welding layer 113. In a specific embodiment, in order to ensure that the first welding layer 113 has sufficient length and / or area to be coated with structural adhesive, the length and / or area of ​​the hollow area 142 can be controlled. For example, the length of the hollow area 142 in the third direction Z can be controlled to be 0.6 to 0.98 of the length of the second sidewall 112 in the third direction Z and / or the area of ​​the hollow area 142 can be controlled to be 0.5 to 0.96 of the area of ​​the second sidewall 112.

[0086] In one embodiment of this utility model, please refer to Figure 8The outer casing also includes a base plate 120, which covers at least one opening of the casing 110. A second weld layer 121 is formed on the side of the base plate 120 away from the casing 110. The second weld layer 121 connects the base plate 120 to the opening so that the base plate 120 seals the opening. That is, the base plate 120 is welded to the casing 110 by top welding. Compared with side welding, this effectively avoids the problem of increased thermal deformation caused by the overlap of the first weld layer 113 and the second weld layer 121, which would reduce the strength of the casing 110. In addition, during the coating process, the protruding edge of the second weld layer 121 is similar to a right angle to some extent. Compared with the stretched arc edge formed by stretching the casing 110, the size fluctuation of the arc is prone to causing wrinkles in the coating. The near right angle allows the insulating film 140 to extend more evenly to the large surface, reducing wrinkles. The yield rate will be further improved. In addition, in order to isolate the electrode assembly and the shell and prevent the electrode assembly from electrochemically corroding the metal shell 110, a Mylar film, also known as a Mylar film, will be wrapped on the outer surface of the electrode assembly. Previously, the shell 110 was stretched and formed to create a stretched arc edge at the transition connection between the base plate 120 and the shell 110. In order to better position and fix the electrode assembly, a bottom support plate is usually set between the Mylar film and the bottom surface of the electrode assembly. However, the base plate 120 connected to the shell 110 through the second welding layer 121 makes the inner bottom surface of the shell a relatively flat plane without an arc transition surface. Therefore, the inner bottom surface of the shell can support the electrode assembly more stably and reliably, so there is no need to set a bottom support plate. Thus, the energy density and space utilization of the battery cell 100 and the battery module assembled from it are improved.

[0087] In one embodiment of this utility model, please refer to Figure 9 , Figure 10 The battery module also includes a frame for fixing and supporting multiple battery cells 100. The bottom surface of the base plate 120 is bonded to the bottom surface 400 of the frame by an adhesive. At least a portion of the second welding layer 121 is embedded in the adhesive. With the above structural design, the weight of the adhesive and the battery cells 100 themselves can effectively suppress and constrain the deformation of the second welding layer 121. In addition, the fact that at least a portion of the second welding layer 121 is embedded in the adhesive can effectively prevent slippage between the bottom surface of the battery cell 100 shell and the bottom surface 400 of the frame, thereby improving the safety of the battery module. Furthermore, the second welding layer 121 can also reduce the external constraint force on the expansion of the electrode assembly plates caused by the structural adhesive and other adhesives being squeezed onto the first sidewall 111 and the second sidewall 112, thereby making the expansion of the plates more uniform.

[0088] The battery pack provided by this utility model includes multiple battery modules as described in any of the above embodiments. In a specific embodiment, multiple battery modules can be electrically connected in series, parallel, or a combination of both and housed in a closed box to form a battery pack.

[0089] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A battery module, characterized in that, include: Multiple battery cells, each battery cell including a housing and an electrode assembly disposed in the housing, the housing including a shell, the shell being a structure formed by bending a metal plate with at least one open end, the shell including two first sidewalls disposed opposite to each other along a first direction and two second sidewalls disposed opposite to each other along a second direction, the first direction being perpendicular to the second direction, at least one of the second sidewalls having a first welding layer distributed along a third direction, the third direction being perpendicular to the first direction and the second direction; Multiple battery cells are arranged along a first direction; At least two of the battery cells are filled with a cushioning element that can undergo elastic deformation between their first sidewalls.

2. The battery module according to claim 1, characterized in that, The width of the first sidewall in the second direction is greater than the width of the second sidewall in the first direction, and the larger surface of the electrode assembly faces the first sidewall.

3. The battery module according to claim 2, characterized in that, The distance between the first weld layer and one of the first sidewalls in the first direction is 1 / 5 to 1 / 3 of the width of the second sidewall in the first direction.

4. The battery module according to claim 2, characterized in that, The distance between the first weld layer and one of the first sidewalls in the first direction is 6 / 25 to 13 / 50 of the width of the second sidewall in the first direction.

5. The battery module according to claim 1, characterized in that, The electrode assembly includes a plurality of cores stacked along the first direction. Each core includes two straight portions arranged opposite each other along the first direction and two arc portions (131) arranged opposite each other along the second direction. Each arc portion has an arc tip that protrudes outward in the second direction. The first welding layer is disposed away from the arc tip in the first direction.

6. The battery module according to claim 5, characterized in that, The electrode assembly includes four cores stacked along the first direction, with the first welding layer located between the core closest to the first sidewall and the arc-shaped tip of the core adjacent to it.

7. The battery module according to claim 1, characterized in that, The outer side of the housing is wrapped with an insulating film, which forms an overlapping area distributed along the third direction at a position corresponding to at least a portion of the first welding layer; or the insulating film has a hollow area at a position corresponding to at least a portion of the first welding layer to expose at least a portion of the first welding layer. The battery module also includes a frame for fixing and supporting multiple battery cells, and the hollow area is bonded to the side wall of the frame or the inner bottom surface of the frame by an adhesive.

8. The battery module according to claim 1, characterized in that, The housing also includes a base plate that covers at least one opening of the housing, and a second weld layer is formed on the side of the base plate away from the housing, the second weld layer connecting the base plate to the opening so that the base plate seals the opening.

9. The battery module according to claim 8, characterized in that, It also includes a frame for fixing and supporting multiple battery cells, wherein the bottom surface of the base plate and the inner bottom surface of the frame are bonded together by an adhesive, and at least a portion of the second welded layer is embedded in the adhesive.

10. A battery pack, characterized in that, Includes the battery module as described in any one of claims 1-9.

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