Battery cell shell, battery cell, battery pack and vehicle

Abstract

The utility model discloses a shell of a battery cell, the battery cell, a battery pack and a vehicle, the shell is provided with an accommodating cavity, and the accommodating cavity is used for accommodating electrolyte; a diffusion groove is formed in the inner wall of the shell and used for diffusing the electrolyte. The diffusion groove is formed in the inner wall of the shell of the battery cell and is used for diffusing the electrolyte, so that the electrolyte is diffused along the extension direction of the diffusion groove, the diffusion rate of the electrolyte is improved, the contents of all components in the electrolyte at all positions of the battery cell are basically the same as much as possible, the phenomenon of local failure of the battery cell is prevented, and the service life of the battery cell is prolonged. And the actual service life of the battery cell is prolonged.

Description

Technical Field

[0001] The present application relates to the field of electricity, and more specifically to a battery cell shell, a battery cell, a battery pack and a vehicle. Background Art

[0002] At present, the consumption of electrolyte additives at different locations of the battery cell is different due to the difference in force, heat, and additive content at different locations. The diffusion of free electrolyte takes a certain amount of time, so the electrolyte additives at some locations will be quickly consumed and cannot be effectively replenished. This leads to an increase in the iron impurity content at these locations, which in turn leads to lithium precipitation, which in turn leads to the failure of the battery cell, making the battery cell shorter than the expected lifespan. Utility Model Content

[0003] The present invention is proposed to solve at least one of the above problems. According to the first aspect of the present application, a shell of a battery cell is provided, the shell having a receiving cavity, the receiving cavity is used to receive an electrolyte; a diffusion groove is provided on the inner wall of the shell, the diffusion groove is used to diffuse the electrolyte.

[0004] In one embodiment of the present application, the diffusion groove has a first end and a second end, wherein the first end is located at one end of the length direction of the accommodating cavity, and the second end is located at the other end of the length direction of the accommodating cavity.

[0005] In one embodiment of the present application, the diffusion slot includes: a linear diffusion slot.

[0006] In one embodiment of the present application, the linear diffusion slot includes: a first diffusion slot, wherein the angle between the extension direction of the first diffusion slot and the length direction of the accommodating cavity is 0° to 30°.

[0007] In one embodiment of the present application, the number of the first diffusion grooves is at least two, and at least two of the first diffusion grooves are arranged in parallel.

[0008] In one embodiment of the present application, the linear diffusion slot includes: a second diffusion slot, and the included angle between the extension direction of the second diffusion slot and the length direction of the accommodating cavity is 60° to 90°.

[0009] In one embodiment of the present application, the number of the second diffusion grooves is at least two, and at least two of the second diffusion grooves are arranged in parallel.

[0010] In one embodiment of the present application, the shell has a first inner wall and a second inner wall opposite to each other in the X-axis direction; wherein the diffusion groove is arranged on the first inner wall and / or the second inner wall.

[0011] In one embodiment of the present application, the shell has a third inner wall and a fourth inner wall opposite to each other in the Y-axis direction; wherein the diffusion groove is arranged on the third inner wall and / or the fourth inner wall.

[0012] In one embodiment of the present application, the cross-section of the diffusion groove is rectangular or trapezoidal, and the depth of the diffusion groove is 0.5 to 20 mm.

[0013] In one embodiment of the present application, the cross-section of the diffusion groove is rectangular, and the width of the diffusion groove is 0.5-10 mm.

[0014] According to the second aspect of the present application, a battery cell is further provided, comprising: a shell of any one of the above-mentioned battery cells, an electrolyte, and a battery cell electrode sheet, wherein the battery cell electrode sheet is accommodated in the accommodating cavity; and the electrolyte is accommodated in the accommodating cavity.

[0015] According to the third aspect of the present application, a battery pack is also provided, comprising: any one of the above-mentioned battery cells.

[0016] According to the fourth aspect of the present application, a vehicle is also provided, the vehicle comprising: any one of the above-mentioned battery packs

[0017] According to the battery cell shell, battery cell, battery pack and vehicle provided in the embodiments of the present application, a diffusion groove is provided on the inner wall of the battery cell shell, and the diffusion groove is used to diffuse the electrolyte, so that the electrolyte is diffused along the extension direction of the diffusion groove, thereby improving the diffusion rate of the electrolyte, and making the contents of each component in the electrolyte at various positions of the battery cell basically the same, thereby preventing local failure of the battery cell and thereby improving the actual life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic cross-sectional view of a shell of a battery cell provided in one embodiment of the utility model;

[0020] Figure 2 A schematic longitudinal cross-sectional view of a shell of a battery cell provided in one embodiment of the utility model;

[0021] Figure 3 A schematic cross-sectional view of a 3-channel, 4-channel and 5-channel embodiment of the present invention;

[0022] Figure 4 A schematic longitudinal cross-sectional view of a 3-channel, 4-channel and 5-channel embodiment of the present invention;

[0023] Figure 5 A schematic diagram of a sampling site of a positive electrode provided in an embodiment of the utility model;

[0024] Figure 6 A schematic diagram of a 4-channel electrolyte diffusion path provided by an embodiment of the utility model;

[0025] Figure 7 This is a comparison chart of the VC content at the positive electrode site ⑤ of the utility model with different paths and the existing normal battery at different cycle numbers;

[0026] Figure 8 This is a comparison chart of the VC content at the positive electrode No. ⑥ site of the utility model with different paths and the existing normal battery at different cycle numbers;

[0027] Fig. 9 This is a comparison diagram of the mean VC content at each position of a 4-channel battery shown in the utility model and a normal battery;

[0028] Fig.10 This is a comparison chart of the 45°C cycle retention rates of different pathways shown in the utility model and existing normal batteries.

[0029] Reference numerals:

[0030] 10-shell 11-first inner wall 12-second inner wall 13-third inner wall 14-fourth inner wall

[0031] 20-accommodating chamber 30-diffusion groove 31-first diffusion groove 32-second diffusion groove DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the utility model more obvious, the exemplary embodiments according to the utility model will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments of the utility model, and it should be understood that the utility model is not limited to the exemplary embodiments described here. Based on the embodiments of the utility model described in the utility model, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the utility model.

[0033] In the following description, a large number of specific details are given to provide a more thorough understanding of the utility model. However, it is obvious to those skilled in the art that the utility model can be implemented without one or more of these details. In other examples, in order to avoid confusion with the utility model, some technical features known in the art are not described.

[0034] It should be understood that the utility model can be implemented in different forms and should not be interpreted as being limited to the embodiments proposed herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the utility model to those skilled in the art.

[0035] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention. The optional embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0036] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0037] The present application embodiment provides a battery cell housing, referring to Figure 1 and Figure 2 The shell 10 has a receiving chamber 20 for receiving electrolyte; a diffusion groove 30 is provided on the inner wall of the shell 10 for diffusing electrolyte.

[0038] In the above scheme, a diffusion groove 30 is provided on the inner wall of the shell 10 of the battery cell, and the diffusion groove 30 is used to diffuse the electrolyte, so that the electrolyte is diffused along the extension direction of the diffusion groove 30, the diffusion rate of the electrolyte is improved, and the content of each component in the electrolyte at each position of the battery cell is made basically the same as much as possible, thereby preventing the occurrence of local failure of the battery cell and thus improving the actual life of the battery cell. The above structures are described in detail below in conjunction with the accompanying drawings.

[0039] When setting the housing 10, refer to Figure 1 and Figure 2, the shell 10 has a receiving cavity 20, which is used to receive the electrolyte. Exemplarily, the shell 10 can be any shell 10 with a hollow cavity, and the hollow cavity can be used as a receiving cavity 20 to receive the electrolyte. Exemplarily, the present application has no restrictions on the form of the battery cell, and the shell 10 can be a shell 10 such as but not limited to a blade-type square shell battery. Regarding the material of the shell 10, it can be any material suitable as the battery cell shell 10. Exemplarily, aluminum can be used as the material for preparing the shell 10. Exemplarily, the shell 10 can have four side panels, and the four side panels are enclosed into a rectangular cylinder, and the battery cell electrode sheet is received in the receiving cavity 20. Exemplarily, two poles are provided at opposite ends of the battery cell, namely a positive pole and a negative pole, and the two poles are respectively led out of the shell 10 from opposite ends of the shell 10. Of course, in other embodiments, the shell 10 can also be a cylindrical shell 10. The electrode chip can be arranged in the receiving cavity 20 in a manner such as but not limited to stacking. An electrolyte is disposed in the containing chamber 20 . The electrolyte may contain fluids of various components and may also contain electrolyte additives added into the electrolyte.

[0040] Exemplarily, the accommodating cavity 20 can also be used to accommodate the cell pole piece. The cell pole piece can be accommodated in the accommodating cavity 20 in a variety of ways. Exemplarily, the cell pole piece can be formed into a pole core structure by lamination or winding process, and then the formed pole core structure is accommodated in the accommodating cavity 20. It should be noted that the way in which the cell pole piece is accommodated in the accommodating cavity 20 is not specifically limited.

[0041] Exemplary, reference Figure 1 and Figure 2 , a coordinate system including an X-axis, a Y-axis, and a Z-axis can be established, and the coordinate system can be a rectangular coordinate system of the space or a non-rectangular coordinate system of the space. Figure 1 and Figure 2, the Z axis can be defined as the length direction of the accommodating cavity 20. Exemplarily, when the battery cell pole piece adopts the lamination process to form the pole core structure and is accommodated in the accommodating cavity 20, the length direction of the battery cell pole piece can be made parallel to the length direction of the accommodating cavity 20. Exemplarily, the battery cell is provided with two poles at opposite ends of the Z axis, namely the positive pole and the negative pole, and the two poles are respectively led out of the shell 10 from opposite ends of the shell 10. Exemplarily, the shell 10 can have pole cover plates at opposite ends of the Z axis, respectively, for fixing the pole and exposing the pole outside the pole cover plate. The Y axis can be defined as the width direction of the accommodating cavity 20. Exemplarily, when the battery cell pole piece adopts the lamination process to form the pole core structure and is accommodated in the accommodating cavity 20, the width direction of the battery cell pole piece can be made parallel to the width direction of the accommodating cavity 20. The X-axis can be defined as the height direction of the accommodating cavity 20. For example, when the battery cell pole pieces are formed into a pole core structure by adopting a lamination process and accommodated in the accommodating cavity 20, the lamination direction of the battery cell pole pieces can be parallel to the height direction of the accommodating cavity 20, that is, the battery cell pole pieces are stacked along the height direction.

[0042] refer to Figure 1 and Figure 2 A diffusion groove 30 is provided on the inner wall of the shell 10, and the diffusion groove 30 is used to diffuse the electrolyte. Since the diffusion groove 30 is provided on the inner wall of the shell 10, even when the battery cell electrode is completely attached to the inner wall of the shell 10, the diffusion groove 30 can still be filled with electrolyte, so that the electrolyte diffuses from the high concentration area to the low concentration area along the extension direction of the diffusion groove 30, so that when the electrolyte at certain positions inside the battery cell is consumed faster, the electrolyte at other positions can be diffused to these positions where the electrolyte is consumed faster along the guidance of the diffusion groove 30, so as to achieve the balance of the electrolyte components at various positions inside the battery cell and prevent the failure of the battery cell locally. A diffusion groove 30 is provided on the inner wall of the shell 10 of the battery cell. The diffusion groove 30 is used to diffuse the electrolyte, so that the electrolyte can be diffused along the extension direction of the diffusion groove 30, thereby improving the diffusion rate of the electrolyte, and making the contents of various components in the electrolyte at various positions of the battery cell basically the same, thereby preventing local failure of the battery cell and thereby improving the actual life of the battery cell.

[0043] When the diffusion slot 30 is arranged, any arrangement method can be adopted. For example, the diffusion slot 30 can be a straight diffusion slot 30, a curved diffusion slot 30, etc., wherein the diffusion slot 30 is mainly divided by the extension method of the diffusion slot 30. The shape of the slot cross section of the diffusion slot 30 can be any shape, for example, the shape of the slot cross section of the diffusion slot 30 can be any shape such as, but not limited to, a rectangle, a trapezoid, an arc, a triangle, a pentagon, etc. Several arrangements of the diffusion slot 30 are introduced as examples below.

[0044] Exemplary, reference Figure 2, the diffusion slot 30 may have a first end and a second end, and the diffusion slot 30 is connected between the first end and the second end. Among them, the first end may be located at one end of the length direction of the accommodating chamber 20, and the second end may be located at the other end of the length direction of the accommodating chamber 20. That is, the two opposite ends of the diffusion slot 30 are respectively located at the two ends of the length direction of the accommodating chamber 20, and the diffusion slot 30 is arranged through the length direction of the inner wall of the shell 10, and the specific penetration direction may be such as but not limited to linear extension, curved extension and the like. It should be explained that the length direction of the accommodating chamber 20 refers to the direction in which the size of the accommodating chamber 20 is the longest. Exemplarily, when the battery cell pole piece adopts a lamination process to form a pole core structure and is accommodated in the accommodating chamber 20, the length direction of the battery cell pole piece may be parallel to the length direction of the accommodating chamber 20. Exemplarily, refer to Figure 1 and Figure 2 The first end of the diffusion groove 30 may be located at one end of the housing 10 in the Z-axis direction, and the second end of the diffusion groove 30 may be located at the other end of the housing 10 in the Z-axis direction.

[0045] With this arrangement, for blade batteries, such as but not limited to, blade batteries have a longer length, so the difference in force, heat, and additive content in the length direction will be more obvious. In particular, during the cycle, due to the difference in force and heat in the length direction, the consumption of electrolyte additives in the length direction is different, and it takes a certain amount of time for the free electrolyte to diffuse in the length direction, so the electrolyte additives at the center position will be quickly consumed and cannot be effectively replenished. The electrolyte additives in the battery cell are mainly used to repair the SEI film of the negative electrode. When the center position is quickly consumed and cannot be effectively replenished, the iron element in the system will come to this position due to the damage of the SEI film to reduce and form iron impurities, while other areas have short diffusion paths, so the electrolyte additives can be effectively replenished, so this phenomenon will not occur; when the center position increases due to the increase in the iron impurity content, lithium precipitation will occur, which will lead to the failure of the single battery cell. Although the additive content in the system can still meet the cycle requirements at this time, the failure of the center position will cause the battery cell to be lower than the expected life.

[0046] Most of the existing technologies increase the concentration of the film-forming additives in the electrolyte to compensate for the problems of uneven distribution of the film-forming additives and untimely diffusion caused by the long diffusion distance in the middle position. However, a higher concentration of film-forming additives will make the battery impedance larger and will greatly increase the cost. In addition, the film-forming additives in other areas of a normal battery are sufficient, and only the central area cannot meet the cycle requirements. Using this method is not worth the loss. The normal battery refers to a battery in the prior art that does not have a diffusion groove 30 on the inner wall of the accommodating cavity 20. In order to solve the problem that the film-forming additives in the central area of ​​blade-type batteries are difficult to replenish, in the scheme shown in some embodiments of the present application, by setting a diffusion groove 30 along the length direction on the inner wall of the shell 10 of the blade battery core, the diffusion groove 30 can balance the concentration of the film-forming additives in the electrolyte at the center of the battery and the cavity positions at both ends, thereby shortening the diffusion path, increasing the replenishment rate of the film-forming additives at the center, and thus improving its cycle life.

[0047] Exemplary, reference Figure 2 and Figure 4 The diffusion slot 30 may include a linear diffusion slot 30. The linear diffusion slot 30 refers to a diffusion slot 30 whose extension direction is a straight line, thereby simplifying the difficulty of setting the diffusion slot 30. The linear diffusion slot 30 has the characteristic of the shortest distance between two points, so that the electrolyte area with a higher concentration can be diffused to the electrode liquid area with a lower concentration more quickly.

[0048] Exemplary, reference Figure 2 and Figure 4 The linear diffusion slot 30 may include: a first diffusion slot 31, and the angle between the extension direction of the first diffusion slot 31 and the length direction of the accommodating cavity 20 is 0° to 30°. Figure 2 and Figure 4 The angle between the extension direction of the first diffusion slot 31 and the length direction of the accommodating cavity 20 can be 0°, that is, the extension direction of the first diffusion slot 31 is parallel to the length direction of the accommodating cavity 20. The angle between the extension direction of the first diffusion slot 31 and the length direction of the accommodating cavity 20 can also be greater than 0° and less than or equal to 30°, so that the electrolyte inside the housing 10 is diffused along the extension direction of the first diffusion slot 31, thereby balancing the electrolyte concentration of the battery cell in the length direction.

[0049] For example, the number of the first diffusion slot 31 may be one. Figure 1 to Figure 4 , the number of the first diffusion slots 31 can be at least two, that is, by providing a plurality of first diffusion slots 31, the concentration balance of the electrolyte in the length direction of the battery cell is improved. Exemplarily, at least two first diffusion slots 31 can be arranged in parallel, that is, at least two first diffusion slots 31 can be arranged in parallel and spaced apart to improve the concentration balance of the electrolyte in the length direction. Exemplarily, refer to Figure 2 The number of the first diffusion grooves 31 provided on the first inner wall 11 or the second inner wall 12 may be three, referred to as three channels. Figure 4 The number of the first diffusion grooves 31 provided on the first inner wall 11 or the second inner wall 12 may be 4 or 5, which are referred to as 4-channels or 5-channels, respectively.

[0050] In some embodiments, reference Figure 2 and Figure 4 The linear diffusion slot 30 may include: a second diffusion slot 32, the angle between the extension direction of the second diffusion slot 32 and the length direction of the accommodating chamber 20 is 60° to 90°. That is, the second diffusion slot 32 may also be arranged in the width or height direction of the battery cell, so that the electrolyte diffuses along the second diffusion slot 32 in the width or height direction of the battery cell, further improving the concentration balance at different positions of the battery cell. For example, refer to Figure 2 and Figure 4 , the extension direction of the second diffusion slot 32 can be perpendicular to the length direction of the accommodating cavity 20, that is, the extension direction of the second diffusion slot 32 is parallel to the width direction or the height direction of the accommodating cavity 20. Exemplarily, when the cell pole piece adopts a lamination process to form a pole core structure and is accommodated in the accommodating cavity 20, the height direction of the cell can be the lamination direction of the cell pole piece, and the width direction of the cell can be the width direction of the cell pole piece.

[0051] For example, the number of the second diffusion slot 32 may be one. Figure 2 and Figure 4 , the number of the second diffusion slots 32 is at least two, and at least two second diffusion slots 32 are arranged in parallel. That is, by arranging a plurality of second diffusion slots 32, the concentration balance of the electrolyte in the height or width direction of the battery cell is improved. Exemplarily, at least two second diffusion slots 32 can be arranged in parallel, that is, at least two second diffusion slots 32 can be arranged in parallel and spaced apart to improve the concentration balance of the electrolyte in the height or width direction of the battery cell.

[0052] Exemplary, reference Figure 1 , Figure 2 , Figure 3 and Figure 4, the housing 10 has a first inner wall 11 and a second inner wall 12 opposite to each other in the X-axis direction; wherein the diffusion groove 30 is arranged on the first inner wall 11 and / or the second inner wall 12. Exemplarily, the X-axis direction may be the height direction of the housing 10, or may be other directions. For example, when the cell pole piece adopts a lamination process to form a pole core structure and is accommodated in the accommodation cavity 20, the X-axis direction may be the lamination direction of the cell pole piece. Exemplarily, when the cell pole piece is laminated from the first inner wall 11 of the housing 10 to the second inner wall 12, the diffusion groove 30 may be arranged on at least one of the first inner wall 11 and the second inner wall 12. At this time, the diffusion groove 30 may be arranged in close contact with a cell pole piece, so as to facilitate the support of the cell pole piece. Specifically, the diffusion groove 30 may be arranged only on the first inner wall 11, and not on the second inner wall 12. The diffusion groove 30 may be arranged only on the second inner wall 12, and not on the first inner wall 11. The diffusion groove 30 may be provided on both the first inner wall 11 and the second inner wall 12. In this case, the diffusion groove 30 may be provided on the first inner wall 11 or the second inner wall 12 in any of the above-mentioned diffusion groove 30 provision methods. It should be noted that this provision method may also be applied to the process of forming a core structure by other non-laminated methods such as, but not limited to, winding the pole piece of the battery cell, and accommodating the core structure in the accommodating cavity 20.

[0053] Exemplary, reference Figure 1 and Figure 3, the shell 10 has a third inner wall 13 and a fourth inner wall 14 opposite to each other in the Y-axis direction. In some embodiments, the diffusion groove 30 is arranged on the third inner wall 13 and / or the fourth inner wall 14 (not shown in the figure). Exemplarily, the Y-axis direction can be the width direction of the shell 10, or it can be other directions. For example, when the battery cell pole piece is formed into a pole core structure by a lamination process and accommodated in the accommodating cavity 20, the Y-axis direction can be the width direction of the battery cell pole piece. Exemplarily, the two edges of the battery cell pole piece parallel to the extension direction can be respectively opposite to the third inner wall 13 and the fourth inner wall 14, at this time, the diffusion groove 30 can be arranged on at least one of the third inner wall 13 and the fourth inner wall 14. At this time, when the battery cell pole piece is laminated in the accommodating cavity 20, the diffusion groove 30 can be arranged opposite to the side wall of each battery cell pole piece, so as to facilitate the balance of electrolyte concentration between different battery cell pole pieces. Specifically, the diffusion groove 30 can be arranged only on the third inner wall 13, and the diffusion groove 30 is not arranged on the fourth inner wall 14. The diffusion groove 30 may be provided only on the fourth inner wall 14, but not on the third inner wall 13. The diffusion groove 30 may be provided on both the third inner wall 13 and the fourth inner wall 14. In this case, the diffusion groove 30 may be provided on the third inner wall 13 or the fourth inner wall 14 in any of the above-mentioned diffusion groove 30 provision methods. It should be noted that this provision method may also be applied to the process of forming a core structure by other non-laminated methods such as, but not limited to, winding the pole piece of the battery cell, and accommodating the core structure in the accommodating cavity 20.

[0054] Exemplarily, the shape of the groove cross section of the diffusion groove 30 can be rectangular or trapezoidal. At this time, the depth of the diffusion groove 30 can be 0.5 to 20 mm. Specifically, the depth of the diffusion groove 30 can be any value between 0.5 and 20 mm, such as 0.5 mm, 2.0 mm, 5.0 mm, 10.0 mm, 15.0 mm, 20.0 mm. It should be explained that the depth of the diffusion groove 30 refers to the direction extending perpendicular to the inner wall of the shell 10 toward the inner wall of the shell 10. When the shape of the groove cross section of the diffusion groove 30 is rectangular, the depth of the diffusion groove 30 is one of the sides of the rectangle, and the other side of the rectangle is the width of the diffusion groove 30. When the shape of the groove cross section of the diffusion groove 30 is trapezoidal, the depth of the diffusion groove 30 is the height of the trapezoid.

[0055] Exemplarily, the cross-section of the diffusion slot 30 may be in the shape of a rectangle, in which case the width of the diffusion slot 30 may be 0.5 to 10 mm. Specifically, the width of the diffusion slot 30 may be any value between 0.5 and 10 mm, such as 0.5 mm, 2.0 mm, 5.0 mm, 77.0 mm, 8.0 mm, and 10.0 mm. It should be explained that the width of the diffusion slot 30 refers to the direction perpendicular to the inner wall surface of the shell 10 and the direction in which the diffusion slot 30 extends. When the cross-section of the diffusion slot 30 is in the shape of a rectangle, the width of the diffusion slot 30 is one of the sides of the rectangle, and the other side of the rectangle is the depth of the diffusion slot 30.

[0056] In some embodiments of the present application, a diffusion groove 30 is introduced as a flow path on the basis of the original blade-type battery side plate. For example, the flow path can be introduced at the XZ plane of the existing blade-type battery (i.e., the battery side plate), and its cross-sectional profile perpendicular to the XZ plane and parallel to the pole cover plane is as shown in FIG. Figure 1 As shown. For example, reference Figure 5 The schematic diagram of the positive electrode sampling site shown, and Figure 6 From the schematic diagram of the four-channel electrolyte diffusion path shown, it can be seen that in the four-channel electrolyte diffusion path shown in the embodiment of the present application, when diffusing from position ③ and position ⑨ to position ⑤, the diffusion path formed by the first diffusion groove 31 and the second diffusion groove 32 can be used to make the electrolyte diffuse between positions ③, ⑨ and ⑤ in a shorter time, thereby improving the electrolyte diffusion rate and thus improving the balance of the electrolyte solubility at various positions in the shell 10.

[0057] In the existing long blade battery system, the space utilization rate is high, so most of the free electrolyte in the battery system is concentrated on both sides of the positive and negative electrodes and in Figure 5 At positions ③ and ⑨. The higher assembly ratio results in less gap between the battery cell pole piece and the inner wall of the shell 10, so the electrolyte film-forming additive component at position ⑥ will be lower than that at ③ and ⑨. If the concentration of the electrolyte film-forming additives in positions ⑥ is close to that in positions ③ and ⑨, the content of the film-forming additives in positions ④ and ⑤ will be close to that in positions ①②⑦⑧. Therefore, after forming a first diffusion groove 31 as a liquid conduction passage on the inner wall of the shell 10 of the battery cell, the film-forming additives at position ⑥ will basically be consistent with those at ③ and ⑨. In some embodiments, a second diffusion groove 32 parallel to the pole cover plate can be introduced on the inner wall of the shell 10 as a liquid flow passage, so that the electrolyte can convect not only along the Z-axis direction, but also along the X-axis or Y-axis direction. Exemplarily, in addition to 3 passages, there can also be 4 passages, 5 passages, etc. Figure 3 and Figure 4As shown. The following is a test of a blade-type square shell battery to compare the effects. The test method is used to perform a performance test comparison between the battery cell shown in the embodiment of the present application and a normal battery in the prior art, wherein the normal battery refers to a battery in the prior art that does not have a diffusion groove 30 set on the inner wall of the accommodating cavity 20.

[0058] First, the shell 10 including the diffusion groove 30 is prepared, and the battery cell is prepared. According to the existing blade battery, when the Al shell of the existing blade battery is prepared, the side plate of the shell 10 of the battery cell is punched out as follows. Figures 1 to 4 The diffusion tank 30 structure shown in the figure is subsequently subjected to the normal battery cell assembly, liquid injection, aging, formation, aging, capacity division and other processes. The following tests are then performed respectively.

[0059] (1) Capacity: At 25°C, fully charge to 3.8V at 0.33C constant current and constant voltage, then discharge to 2.0V at 0.33C constant current after standing for 3 times. The third discharge capacity is recorded as Q0.33, in Ah.

[0060] (2) 45°C temperature cycle: At 25°C, charge and discharge three times at 1C, with a voltage range of 2.0-3.8V, and calibrate the third discharge capacity as the battery capacity Q1; after calibrating the capacity, charge to 3.8V at 45°C with a constant current and constant voltage of 1*Q1, with a cut-off current of 0.05Q1, then let stand for 30 minutes, discharge to 2.0V with a constant current of 1*Q1, then let stand for 30 minutes; cycle the above steps 300, 500, 800, and 1000 times;

[0061] (3) Regional electrolyte film-forming additive test: After cycling at 45°C, the battery was discharged to 0% SOC and disassembled. Figure 3 Schematic diagram of positive electrode sheet sampling. Use a fixed-size sampler (when sampling, the diaphragm opposite the positive electrode needs to be sampled at the same time to prevent rapid evaporation of the electrolyte). Take a 14mm diameter disc, soak it in an organic solvent, shake it with ultrasound, and then test it with GC-MS to obtain the content of film-forming additives in each area (VC is mainly used as the negative electrode film-forming additive in this experiment) in %.

[0062] Table 1-VC content on the positive electrode side at different cycle numbers

[0063]

[0064] By comparing Table 1 and Figure 7-Figure 8It can be seen that the VC content added to the film at position ⑤ of the 3-channel, 4-channel, and 5-channel batteries during the cycle is much higher than that of normal batteries. The VC content has a positive correlation with the battery cycle process, mainly because VC will replenish the damaged SEI film during the cycle, which can prevent impurity ions from gaining electrons at the negative electrode and then depositing on the negative electrode surface. Position ⑤ in a normal battery is located in the center of the electrode, and the blade-type battery has a higher assembly ratio, resulting in the free electrolyte being concentrated at both ends of the positive and negative electrodes, among which position ⑥ ( Figure 8 ) cannot be replenished quickly, which results in the electrolyte diffusion path only being able to diffuse from both ends to the center. In addition, due to the distance problem, the electricity, heat, and force on the surface of the blade-type battery will increase the VC consumption at position ⑤, and it cannot be effectively replenished, so the VC content at position ⑤ is consumed quickly, and then more impurities are deposited at the center, making the regional position ineffective. In the embodiment of the present application, 3-channel, 4-channel, and 5-channel batteries are introduced into the inner wall of the shell 10. Since there are flow conduction channels on the side plates of the battery cell, the electrolyte free at the positive and negative ends can quickly diffuse to position ⑥, and the VC content in this area is increased from Figure 7 It can be seen that after having an additional pathway, the VC content at site ⑥ remains sufficient during the circulation process, and then during the circulation process, the VC at site ⑥ can diffuse directly to site ⑤, shortening the diffusion path (e.g. Figure 8 Secondly, the VC contents of sites ⑤ and ⑥ of the 4-channel battery and the 5-channel battery are basically the same, which indicates that the additional liquid flow paths in the battery have reached equilibrium.

[0065] refer to Fig. 9 By comparing the VC content of normal batteries and 4-channel batteries at various positions, it can be seen that in normal batteries, the average VC values ​​of positions ①-③ and ⑦-⑨ are higher than those of positions ④-⑥, which indicates that the free electrolyte is on both sides of the positive and negative electrodes, and the rate of diffusion to the middle is much lower than that on both sides, which leads to the VC of positions ④-⑥ being almost exhausted after 800-1000 cycles, while positions ①-③ and ⑦-⑨ still have sufficient VC content, but they cannot diffuse to the center; while the VC content of positions ①-⑨ in 4-channel batteries can basically stabilize at the same level, which ensures the consistency of electrolyte distribution in the blade battery during the cycle. Reference Fig.10 It can also be seen from the 45℃ cycle retention rate that the normal battery without liquid flow path has a diving phenomenon after 1000 cycles, which is positively correlated with the exhaustion of VC at site ⑤; while the 3-channel, 4-channel, and 5-channel batteries have basically similar retention rates during the 45℃ cycle process, and there is no diving phenomenon, which is consistent with the VC results of sites ④-⑥.

[0066] In the various embodiments shown above, a diffusion groove 30 is provided on the inner wall of the shell 10 of the battery cell. The diffusion groove 30 is used to diffuse the electrolyte, so that the electrolyte is diffused along the extension direction of the diffusion groove 30, thereby improving the diffusion rate of the electrolyte, and making the contents of each component in the electrolyte at various positions of the battery cell basically the same, thereby preventing local failure of the battery cell and thereby improving the actual life of the battery cell.

[0067] In some embodiments, the present invention introduces a diffusion groove 30 as a flow path on the side plate of the blade battery. Since the blade battery is longer in the length direction, the difference in force, heat, and additive content in the length direction will be more obvious. In particular, during the cycle, due to the difference in force and heat in the length direction, the consumption of electrolyte additives in the length direction is different, and it takes a certain time for the free electrolyte to diffuse in the length direction. Therefore, the electrolyte additives at the center position will be quickly consumed and cannot be effectively replenished, which will cause the Fe dissolution and Fe deposition of the pole piece in the middle position to be more significant, and will also cause lithium precipitation in the central area of ​​the battery. In some embodiments of the present application, by introducing a diffusion groove 30 as a flow path on the side plate of the blade battery, the flow path will conduct convection and diversion of the electrolyte in the middle position and the cavity position at both ends of the blade battery, accelerating the problem of uniform electrolyte in the overall battery cell, and due to the introduction of the flow path, the diffusion path can be reduced, the consistency of the electrolyte in different areas of the battery is improved, and the risk of failure due to the central area is reduced.

[0068] In addition, the present application also provides a battery cell, referring to Figure 1 and Figure 2 The battery cell comprises: a shell 10 of any one of the above-mentioned battery cells, an electrolyte, and a battery cell electrode piece, the battery cell electrode piece is accommodated in a receiving cavity 20; the electrolyte is accommodated in the receiving cavity 20.

[0069] Exemplarily, multiple cell pole pieces can be stacked in the accommodating cavity 20, and the length direction of each cell pole piece is parallel to the length direction of the accommodating cavity 20. That is, multiple cell pole pieces are arranged in the accommodating cavity 20 in a stacked manner to increase the assembly density of the cell pole pieces, thereby increasing the energy density of the battery cell.

[0070] Furthermore, an embodiment of the present application also provides a battery pack, which includes: any one of the above-mentioned battery cells.

[0071] In addition, an embodiment of the present application further provides a vehicle, the vehicle comprising: any one of the above-mentioned battery packs. The vehicle may be any type of vehicle such as an electric vehicle, a hybrid vehicle, etc.

[0072] The utility model has been described through the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the utility model to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the utility model is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the utility model, and these variations and modifications all fall within the scope of protection claimed by the utility model. The protection scope of the utility model is defined by the attached claims and their equivalents.

Claims

1. A battery cell housing, characterized in that: The shell has a containing cavity, and the containing cavity is used to contain electrolyte; the inner wall of the shell is provided with a diffusion groove, and the diffusion groove is used to diffuse the electrolyte; The diffusion groove has a first end and a second end, and the diffusion groove is connected between the first end and the second end, wherein the diffusion groove is arranged in the length direction of the inner wall of the shell, the first end is located at one end of the length direction of the accommodating cavity, and the second end is located at the other end of the length direction of the accommodating cavity; the length direction of the accommodating cavity refers to the direction in which the size of the accommodating cavity is the longest.

2. The housing according to claim 1, characterized in that The diffusion slot includes: a linear diffusion slot.

3. The housing according to claim 2, characterized in that The linear diffusion tank comprises: The first diffusion groove has an included angle of 0° to 30° between an extending direction of the first diffusion groove and a length direction of the accommodating cavity.

4. The housing according to claim 3, characterized in that The number of the first diffusion grooves is at least two, and at least two of the first diffusion grooves are arranged in parallel.

5. The housing according to claim 2, characterized in that The linear diffusion tank comprises: The second diffusion groove has an included angle of 60° to 90° between an extending direction of the second diffusion groove and a length direction of the accommodating cavity.

6. The housing according to claim 5, characterized in that The number of the second diffusion grooves is at least two, and at least two of the second diffusion grooves are arranged in parallel.

7. The housing according to claim 1, wherein: The shell has a first inner wall and a second inner wall opposite to each other in the X-axis direction; Wherein, the diffusion groove is arranged on the first inner wall and / or the second inner wall.

8. The housing according to claim 1, wherein: The shell has a third inner wall and a fourth inner wall opposite to each other in the Y-axis direction; Wherein, the diffusion groove is arranged on the third inner wall and / or the fourth inner wall.

9. The housing according to claim 1, wherein: The cross section of the diffusion groove is in a rectangular or trapezoidal shape, and the depth of the diffusion groove is 0.5 to 20 mm.

10. The housing according to claim 1, wherein: The cross section of the diffusion groove is in a rectangular shape, and the width of the diffusion groove is 0.5 to 10 mm.

11. A battery cell, characterized in that: include: The shell of the battery cell according to any one of claims 1 to 10; A battery cell pole piece, accommodated in the accommodation cavity; The electrolyte is contained in the containing cavity.

12. A battery pack, characterized in that: include: The battery cell as claimed in claim 11.

13. A vehicle, characterized in that: include: The battery pack as claimed in claim 12.

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