Battery cell and battery module

Abstract

The utility model provides a kind of battery monomer and battery module, battery monomer includes: electrode assembly;And for accommodating electrode assembly shell, shell includes shell and bottom plate;Shell is by the structure of open both ends 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, the width of first side wall in second direction is greater than the width of second side wall in first direction, at least one second side wall is formed with first welding layer distributed along third direction, third direction is perpendicular to first direction and second direction, first welding layer connects the opposite ends of metal plate to make metal plate surround and form shell;Bottom plate covers one opening of shell, and first welding layer is formed with on the side of bottom plate away from shell, first welding layer connects bottom plate and opening, the shell of above-mentioned structural design can effectively improve the structural strength of battery monomer.

Description

Technical Field

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

[0002] In the development of battery technology, in order to meet the higher energy requirements of electrical equipment, battery cells and battery modules are also being manufactured with larger outlines. In order to process the outer shell of the battery cell with a larger outline, a feasible method is to use metal plates to bend and splice them and then weld them into an outer shell. Since the strength of the weld is less than that of the base material, in order to ensure its safety performance and working reliability, how to improve the structural strength of the battery cell and battery module has become an urgent technical problem 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 cell that can improve the structural strength of the battery.

[0004] This utility model also provides a battery module having the above-mentioned battery cells.

[0005] The battery cell provided in the first aspect of this utility model includes: an electrode assembly; and a housing for housing the electrode assembly, the housing including a shell and a base plate;

[0006] The housing is a structure with open ends formed by bending a metal plate. The housing includes two first sidewalls arranged opposite each other along a first direction and two second sidewalls arranged opposite each other along a second direction. The first direction is perpendicular to the second direction. The width of the first sidewall in the second direction is greater than the width of the second sidewall in the first direction. At least one of the second sidewalls has a first welded layer distributed along a third direction. The third direction is perpendicular to the first direction and the second direction. The first welded layer connects the opposite ends of the metal plate so that the metal plate encloses the housing.

[0007] The base plate covers one of the openings 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 and the opening.

[0008] In one embodiment of this utility model, the excess height of the second welding layer is less than 0.1 mm.

[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 excess height of the first weld layer facing the outside of the housing is less than 0.1 mm and / or the excess height of the first weld layer facing the inside of the housing is less than 0.1 mm.

[0011] In one embodiment of the present invention, the outer shell further includes a cover plate that covers another opening of the shell. The outer periphery of the cover plate has a flange that can overlap the end faces of the first sidewall and the second sidewall. The flange is welded to each of the first sidewall and the second sidewall to form a third welded layer.

[0012] The battery cell provided by this utility model has at least the following technical effects:

[0013] Since the width of the second sidewall is smaller than that of the first sidewall, and the electrode assembly generally faces the first direction with its larger surface, while the motor assembly is more prone to expansion, the deformation of the housing on the first sidewall is greater than that on the second sidewall. Therefore, setting the first welding layer on the second sidewall can minimize the deformation at the first welding layer, thereby ensuring the strength of the first welding layer. The second welding layer is formed on the side of the base plate away from the housing, that is, the periphery of the base plate is welded to the first and second sidewalls by top welding. Compared with the side welding method, this can effectively reduce or even avoid the problem of reduced shell strength caused by the thermal deformation due to the overlap of the first and second welding layers. By setting the first and second welding layers as described above, the strength of the battery cell shell can be effectively improved, thereby improving the safety performance and operational reliability of the battery cell.

[0014] The excess height of the second welding layer is less than 0.1mm to prevent excessive excess height from causing geometric abrupt changes at the weld toe of the second welding layer, i.e., the junction between the surface of the second welding layer and the base material, which could lead to stress concentration and fatigue crack propagation. This further ensures the structural strength of the battery cell casing and also avoids the problem that excessive excess height can easily puncture the insulating film wrapped on the outer wall of the casing.

[0015] The battery module provided in the second aspect of this utility model includes a plurality of battery cells as described in any of the first aspects, and a frame supporting the plurality of battery cells. The plurality of battery cells are arranged in the frame along a first direction. The frame includes a bottom frame that supports the bottom plate of the battery cells.

[0016] In one embodiment of the present invention, the base plate and the base frame are bonded together by an adhesive, and at least a portion of the second welding layer is embedded in the adhesive.

[0017] In one embodiment of the present invention, the frame further includes a side frame that supports at least one of the second sidewalls of the housing.

[0018] In one embodiment of the present invention, the outer side of the housing is wrapped with an insulating film, and a hollow area is formed at a position corresponding to at least a portion of the first welding layer of the insulating film. The hollow area is bonded to the side wall of the frame by an adhesive.

[0019] In one embodiment of the present invention, at least two of the first sidewalls are filled with a buffer member that can undergo elastic deformation.

[0020] The battery module provided by this utility model has at least the following technical effects:

[0021] The use of battery cells formed by the above welding method also gives the battery module higher structural strength. Combined with the arrangement of battery cells along the first direction in the frame of the battery module, the structural strength, safety performance and operational reliability of the battery module are further enhanced. Attached Figure Description

[0022] 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.

[0023] In the attached diagram:

[0024] Figure 1 An isometric view of a single battery cell provided in an embodiment of this utility model;

[0025] Figure 2 This is a view along a third direction of a portion of a battery cell, including an electrode assembly, a first sidewall, a second sidewall, and a first welding layer, provided in one embodiment of the present invention.

[0026] Figure 3 This is a view along a third direction of a portion of a battery cell, including an electrode assembly, a first sidewall, a second sidewall, and a first welding layer, provided in another embodiment of the present invention.

[0027] Figure 4 This is an isometric view of a single battery cell from another perspective provided in one embodiment of the present invention;

[0028] Figure 5 This is a cross-sectional view of a portion of the battery module provided in one embodiment of the present invention, with the cross-section parallel to a third direction.

[0029] Figure 6 for Figure 5 A magnified view of part A;

[0030] Figure 7 This is an expanded view of a portion of the battery module;

[0031] Figure 8 The graph is a plotted graph using simulation data of a shell with dimensions of 74.8 mm, 319.141 mm, and 238.7 mm in the first, second, and third directions, respectively.

[0032] Figure 9 The graph is a plotted graph based on simulation data of a shell with dimensions of 56.8 mm, 319.141 mm, and 238.7 mm in the first, second, and third directions, respectively.

[0033] Figure 10 The graph is a plot of simulation data of a shell with dimensions of 74.8 mm, 499.14 mm, and 238.7 mm in the first, second, and third directions, respectively.

[0034] Figure 11 The graph is a plotted graph using simulation data of a shell with dimensions of 99.8 mm, 499.14 mm, and 300 mm in the first, second, and third directions, respectively.

[0035] The markings are as follows:

[0036] 100, Housing; 110, First sidewall; 120, Second sidewall; 121, First weld layer; 200, Base plate; 210, Second weld layer; 300, Cover plate; 310, Flange; 320, Third weld layer; 400, Insulating film; 410, Hollowed-out area; 500, Base frame; 600, Buffer; 700, Heat insulation pad; 800, Electrode assembly; X, First direction; Y, Second direction; Z, Third direction. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] The cylindrical shell and base plate of a battery cell are usually formed by stamping and stretching a single sheet of metal on a mold. In modern production, the outer contour of the shell is getting larger and larger. However, due to the tonnage and stroke limitations of the stretching equipment, stretching is basically impossible when the shell length exceeds 350mm or the height exceeds 240mm. In the prior art, in order to solve the above problems, the metal sheet is bent, spliced, and welded at the splice to form a large-sized shell, and then the base plate is welded on the shell. However, compared with the shell formed by stretching, the shell formed by splicing has an additional welding layer. Since the welding layer is more prone to cracking than other areas, it will affect the strength of the battery cell shell, and thus also affect the structural strength of the battery module formed by arranging and assembling multiple battery cells. In addition, since the welding layer protrudes from the shell, there is also a risk of puncturing the separator of the electrode assembly. This utility model improves the strength of the battery cell shell by reasonably arranging the position of the welding layer and the welding parameters, thereby ensuring the safety performance and operational reliability of the battery cell and the battery module.

[0040] The technical solution of this utility model will be described in detail below with reference to specific embodiments:

[0041] Please see Figures 1-7 The battery cell provided in the first aspect of this utility model includes: an electrode assembly 800; and a housing for housing the electrode assembly 800, the housing including a shell 100 and a base plate 200; the shell 100 is a structure with open ends formed by bending a metal plate, the shell 100 including two first sidewalls 110 disposed opposite each other along a first direction X, and two second sidewalls 120 disposed opposite each other along a second direction Y, the first direction X being perpendicular to the second direction Y, the width of the first sidewall 110 in the second direction Y being greater than the width of the second sidewall 120 in the first direction X, at least one of the second sidewalls... A first weld layer 121 is formed on the sidewall 120 along a third direction Z, which is perpendicular to the first direction X and the second direction Y. The first weld layer 121 connects the opposite ends of the metal plate to enclose the metal plate and form a shell 100. The bottom plate 200 covers an opening of the shell 100, and a second weld layer 210 is formed on the side of the bottom plate 200 away from the shell 100. The second weld layer 210 connects the bottom plate 200 and the opening to seal the opening. In a specific embodiment, aluminum alloy or stainless steel plates can be bent and then spliced ​​and welded to form a cylindrical shell 100. Figure 2 As shown, two metal plates are used. Each metal plate is bent once, and then the bent metal plates are spliced ​​and welded together. At this time, a first weld layer 121 will be formed on both second sidewalls 120 of the shell 100. Alternatively, it can be done as follows: Figure 3 As shown, a metal plate is used, and after multiple bends, two opposite metal edges are aligned and spliced ​​on one of the second sidewalls 120. At this time, only one first welding layer 121 is formed on one of the second sidewalls 120 of the housing 100. After obtaining the cylindrical housing 100, a bottom plate 200 is welded to one opening of the housing 100. In a specific embodiment, in order to ensure the structural strength of the housing and avoid problems such as affecting the energy density or causing excessive weight due to the excessive thickness of the battery cell housing, two first sidewalls 110 and two second sidewalls 120 can be formed by using an aluminum alloy plate with a thickness of 0.8mm. A bottom plate with a thickness of 1.5mm is welded to the housing 100. In order to ensure the firmness and smoothness of the first welding layer 121 and the second welding layer 210, a laser welding method with high energy density can be used for welding.

[0042] Since the width of the second sidewall 120 is smaller than the width of the first sidewall 110, the electrode assembly generally faces the first direction X, and the large surface of the motor assembly is more prone to expansion. Therefore, the deformation of the housing 200 on the first sidewall 210 is greater than the deformation on the second sidewall 220. Thus, setting the first welding layer 221 on the second sidewall 220 can minimize the deformation at the first welding layer 221, thereby ensuring the strength of the first welding layer 121. The second welding layer 210 is formed on the side of the base plate 200 away from the housing 100, that is, the periphery of the base plate 200 is welded to the first sidewall 110 and the second sidewall 120 by top welding. Compared with the side welding method, it can effectively reduce or even avoid the problem of reduced shell strength caused by the increased thermal deformation due to the overlap of the first welding layer 121 and the second welding layer 210. Through the above-mentioned setting of the first welding layer 121 and the second welding layer 210, the strength of the battery cell shell can be effectively improved, thereby improving the safety performance and operational reliability of the battery cell.

[0043] In addition, during the process of covering the outer shell with the insulating film 400, the raised edge of the second welding layer 210 is similar to a right angle. Compared with the stretched arc edge formed by stretching the shell 100 and the base plate 200, the fluctuation in the size of the arc is more likely to cause wrinkles in the film. However, the near right angle allows the insulating film 400 to extend more evenly to the first sidewall 110, and the wrinkle rate will be further improved.

[0044] In one embodiment of the present invention, the excess height of the second welding layer 210 is less than 0.1 mm to prevent excessive excess height from causing geometrical abrupt changes at the weld toe of the second welding layer 210, i.e., the junction between the surface of the second welding layer 210 and the base material, which would lead to stress concentration and fatigue crack propagation. This further ensures the structural strength of the battery cell casing and also avoids the problem that excessive excess height can easily puncture the insulating film 400 wrapped on the outer wall of the casing.

[0045] Considering that the battery cell will experience negative pressure, gas filling, expansion and other conditions, in order to ensure the structural strength of the battery cell throughout its entire life cycle, the stress of the first weld layer 121 should be an ideal small stress value under the above conditions. The following are the stress conditions at the first weld layer 121 obtained from simulation experiments of shells 100 of different sizes under different conditions.

[0046] Table 1 presents simulation data for the casing 100 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 100 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 121 and the first sidewall 110 in the first direction X (hereinafter referred to as the position of the first welding layer 121). These distance values ​​were then converted into percentages of the length of the casing 100 in the first direction X, resulting in the data in the second column of Table 1. That is, from 7.49% to 50%. In order to obtain the stress under different working conditions, the following constraints were set in the simulation software: a negative pressure of 0.1 MPa inside the shell 100, a low pressure working condition where the shell 100 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 800 is set to 6%. The stress values ​​of the first weld layer 121 shown in the third, fourth, and fifth columns of Table 1 were obtained respectively. For example, when the distance of the first weld layer 121 is 5.6 mm as shown in the first row, the stress at the first weld layer 121 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 it and other stress values ​​under this working condition. 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 121 is 37.4 mm, the length ratio of it to the shell 100 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 121 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 121 in other positions and working conditions can be obtained.

[0050] Table 2

[0051]

[0052] Further normalization processing of the above optimization ratios is performed, that is, the largest optimization ratio is used as the standard, and the optimization ratios at other positions of the first weld layer 121 are calculated and their ratios are compared. For example, under negative pressure conditions, the largest optimization ratio is 93.57% of the first weld layer 121 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 121 is 56.89%, and the ratio of 93.57% 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 121 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 121 is used as the horizontal axis, resulting in the following: Figure 8As shown in the graph, under both negative pressure and inflation conditions, the normalized optimization result of the stress value is negatively correlated with the position of the first weld layer 121; that is, the smaller the position of the first weld layer 121, the better the optimization result. Under free expansion conditions, except for the distance of 5.6mm at the first location, the normalized optimization result is positively correlated with the position of the first weld layer 121; that is, the larger the position of the first weld layer 121, the better the optimization result. Plotting a horizontal target line with a vertical axis of 10% on the graph shows that the curves under all three conditions are above this target line. This means the ratio of the position of the first weld layer 121 to the length of the shell 100 in the first direction X is between 21% and 36%. In other words, when the position of the first weld layer 121 is within this range, the normalized optimization ratio of the stress value at the first weld layer 121 can be guaranteed to be above 10% under all conditions, resulting in a relatively ideal and smaller stress value at the first weld layer 121.

[0056] In addition, a fixed value comparison analysis can also be conducted. For example, if the first weld layer 121 is located at the midpoint of the shell 100 in the first direction X and the position of the first weld layer 121 is 14.4 mm away, the stress values ​​of the first weld layer 121 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 121 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 121 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 actual applications, the difference between the two under constrained expansion conditions should be less than 17%. That is, when the first weld layer 121 is in the offset position, compared with the position in the middle, although the stress value at the first weld layer 121 under free expansion conditions will increase slightly, it can significantly reduce the stress value at the first weld layer 121 under negative pressure and inflation conditions.

[0057] Similarly, Table 4 below shows the data obtained from simulation experiments on a smaller-sized shell 100 with dimensions of 319.141 mm, 56.08 mm, and 152.987 mm. Eleven groups of relatively evenly spaced first weld layer 121 positions were selected, and the stress values ​​of the first weld layer 121 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 9 The normalized optimization result curve obtained using the data in the table above shows that when the target line is equal to 10%, the curves under both working conditions are located above the target line on the horizontal axis, that is, the ratio of the length of the first weld layer 121 to the length of the shell 100 in the first direction X is between 11% and 42%.

[0064] Table 6 below shows the stress data of the first weld layer 121 at different locations obtained after simulation analysis of the shell 100 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 10 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 located above the target line on the horizontal axis, that is, the ratio of the length of the first weld layer 121 to the length of the shell 100 in the first direction X is between 10% and 38%.

[0071] Table 8 below shows the stress data of the first weld layer 121 at different locations obtained after simulation analysis of the shell 100 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 11 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 121 to the length of the shell 100 in the first direction X is between 8% and 31%.

[0078] From the simulation experimental data and graphical analysis of the above four different sizes of shell 100, 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 121 to the length of the shell 100 in the first direction X falls between 21% and 36%, 11% and 42%, 10% and 38%, and 8% and 31%, respectively. 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 121 to the length of the shell 100 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 121 can achieve a relatively ideal small value.

[0079] In one embodiment of the present invention, the distance between the first welding layer 121 and one of the first sidewalls 110 in the first direction X is 1 / 5 to 1 / 3 of the width of the second sidewall 120 in the first direction X.

[0080] By offsetting the first welding layer 121 to the second wall surface of the housing 100, i.e. the side with a smaller area of ​​the housing 100, 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 100, the stress on the first welding layer 121 is effectively reduced, and the overall strength of the spliced ​​housing 100 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 weld of the housing 100 or insufficient sealing. Since the stress on the first welding layer 121 is small, the housing 100 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 100 is also convenient for mass production of large-profile battery cell housings 100.

[0081] In one embodiment of this utility model, the excess height of the first welding layer 121 facing the outside of the housing 100 is less than 0.1 mm, so as to prevent the excessive excess height from causing a geometrical abrupt change at the weld toe of the first welding layer 121, that is, at the junction of the surface of the first welding layer 121 and the base material, which would lead to stress concentration and fatigue crack propagation. This further ensures the structural strength of the battery cell housing 100 and also avoids the problem that the excessive excess height is more likely to puncture the insulating film 400 wrapped on the outer wall of the housing 100.

[0082] In one embodiment of the present invention, the excess height of the first welding layer 121 facing the inside of the housing 100 is less than 0.1 mm. In addition to preventing excessive excess height from causing stress concentration and fatigue crack propagation at the weld toe of the first welding layer 121, it can also effectively avoid excessive excess height protrusion piercing the diaphragm located in the core of the electrode assembly 800, thereby causing problems such as short circuit of the positive and negative electrodes or lithium plating of the diaphragm.

[0083] In one embodiment of this utility model, please refer to Figure 4 The housing also includes a cover plate 300, which covers another opening in the housing 100. The outer periphery of the cover plate 300 has a flange 310 that can overlap the end faces of the first side wall 110 and the second side wall 120. The flange 310 is welded to each of the first side wall 110 and the second side wall 120 to form a third weld layer 320. Since the cover plate 300 is welded to the housing 100 after the electrode assembly 800 is placed into the housing 100, if a top welding method is used, the laser can easily damage the electrode through the gap. Therefore, a safer side-welding method is used to weld the cover plate 300 onto the housing 100. In order to ensure the energy density and weight control of the battery cells and the battery modules assembled from them, the housing 100 will use a thinner metal plate in actual production. Since the explosion-proof valve and positive and negative terminals are to be integrated on the cover plate 300, the wall thickness of the cover plate 300 is generally greater than that of the housing 100. Therefore, it is easier to process the flange 310 on the cover plate 300 to facilitate side welding.

[0084] Please refer to the battery module provided in the second aspect embodiment of this utility model. Figure 7The battery module includes multiple battery cells in any embodiment of the first aspect, and a frame supporting the multiple battery cells. The multiple battery cells are arranged in the frame along the first direction X. When the multiple battery cells are assembled into a battery module, two end plates are generally set along the first direction X to clamp the multiple battery cells. Therefore, a compressive force along the first direction X is generated between the adjacent first sidewalls 110 of the multiple battery cells. Since the first weld layer 121 is formed on the second sidewall 120, the compressive force at this time is equivalent to the tangential compressive force applied to the first weld layer 121. If the multiple battery cells are arranged along the second direction Y, the compressive force at this time is equivalent to the normal shear force applied to the first weld layer 121. The first weld layer 121 is a splicing weld layer with tensile strength higher than shear strength. Therefore, the above arrangement of battery cells is equivalent to enhancing the structural strength of the battery module. The frame includes a bottom frame that supports the bottom plate of the battery cells. The bottom frame can effectively provide vertical support for the multiple battery cells, thereby further enhancing the structural strength of the battery module.

[0085] In one embodiment of this utility model, please refer to Figure 5 , Figure 6 The base plate 200 and the base frame 500 are bonded together by an adhesive, and at least a portion of the second welding layer 210 is embedded in the adhesive. In a specific embodiment, the adhesive can be a structural adhesive. With the above structural design, the adhesive and the weight of the battery cell 100 itself can effectively suppress and constrain the deformation of the second welding layer 210. In addition, the fact that at least a portion of the second welding layer 210 is embedded in the adhesive can also effectively prevent slippage between the bottom surface of the battery cell casing and the base frame 500, thereby improving the safety of the battery module. Furthermore, the second welding layer 210 can also reduce the external constraint force on the expansion of the electrode assembly 800 electrode sheet caused by the structural adhesive and other adhesives being squeezed onto the first sidewall 110 and the second sidewall 120, thereby making the electrode sheet stretch more uniformly.

[0086] In one embodiment of the present invention, the frame further includes a side frame, which supports at least one second sidewall of the housing. The side frame can provide horizontal support for the battery cell, preventing the battery cell from swaying horizontally during use, thereby further improving the structural strength of the battery module.

[0087] In one embodiment of this utility model, please refer to Figure 7An insulating film 400 is wrapped around the outer side of the housing 100. A hollow area 410 is formed at a position corresponding to at least a portion of the insulating film 400 and the first welding layer 121. The hollow area 410 is bonded to the side wall of the frame by an adhesive. In a specific embodiment, the adhesive can be structural adhesive or the like. In addition to firmly fixing the battery cell in the frame of the battery module, the adhesive can also effectively suppress and constrain the deformation of the first welding layer 121 located in the hollow area 410, thereby further improving the strength of the battery cell housing 100 and the structural strength of the battery module assembled from the battery cells.

[0088] In one embodiment of this utility model, please refer to Figure 7 At least two first sidewalls 110 are filled with elastically deformable buffer members 600. In specific embodiments, rubber-based materials or silicone materials that simultaneously possess flame retardancy and good elasticity can be used, or materials such as... Figure 7 The structure shown is a combination of elastic elements made into a U-shaped structure with an area equivalent to that of the first sidewall 110, and heat insulation pads 700 filled in the U-shaped gaps. In addition, to enhance the cushioning effect, buffer elements 600 can be filled between each pair of adjacent first sidewalls 110. Buffer elements 600 can effectively absorb some of the forces between the first sidewalls 110 when the battery module is assembled or when the battery module is used on electrical equipment and vibrates. It also reduces the forces on the first weld layer 121, thereby further enhancing the structural strength of the battery module.

[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 cell, characterized in that, include: Electrode assembly; as well as A housing for accommodating the electrode assembly, the housing comprising a casing and a base plate; The housing is a structure with open ends formed by bending a metal plate. The housing includes two first sidewalls arranged opposite each other along a first direction and two second sidewalls arranged opposite each other along a second direction. The first direction is perpendicular to the second direction. The width of the first sidewall in the second direction is greater than the width of the second sidewall in the first direction. At least one of the second sidewalls has a first welded layer distributed along a third direction. The third direction is perpendicular to the first direction and the second direction. The first welded layer connects the opposite ends of the metal plate so that the metal plate encloses the housing. The base plate covers one of the openings 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 and the opening.

2. The battery cell according to claim 1, characterized in that, The excess height of the second weld layer is less than 0.1 mm.

3. The battery cell according to claim 1, 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 cell according to claim 1, characterized in that, The excess height of the first weld layer facing the outside of the housing is less than 0.1 mm and / or the excess height of the first weld layer facing the inside of the housing is less than 0.1 mm.

5. The battery cell according to claim 1, characterized in that, The housing also includes a cover plate that covers another opening of the housing. The outer periphery of the cover plate has a flange that can overlap the end faces of the first sidewall and the second sidewall along the third direction. The flange is welded to each of the first sidewall and the second sidewall to form a third weld layer.

6. A battery module, characterized in that, The device includes a plurality of battery cells as described in any one of claims 1-5, and a frame supporting the plurality of battery cells, wherein the plurality of battery cells are arranged in the frame along a first direction, and the frame includes a bottom frame that supports the bottom plate of the battery cells.

7. The battery module according to claim 6, characterized in that, The base plate and the base frame are bonded together by adhesive, and at least part of the second weld layer is embedded in the adhesive.

8. The battery module according to claim 6, characterized in that, The frame also includes side frames that support at least one of the second sidewalls of the housing.

9. The battery module according to claim 8, characterized in that, The outer side of the housing is wrapped with an insulating film. At least a portion of the insulating film and the first welding layer have hollowed-out areas. The hollowed-out areas are bonded to the side wall of the frame by adhesives.

10. The battery module according to claim 6, characterized in that, At least two of the first sidewalls are filled with a cushioning element that can undergo elastic deformation.

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