Battery case and lithium battery

Abstract

The present application discloses a battery case and a lithium battery, in which the battery case has a cylindrical structure with both ends open, and includes a case body formed by bending and welding a plate material and having a first side edge and a second side edge welded together and provided with a positioning mechanism, a case bottom welded to the first end of the case body and configured to close the first end of the case body, and a case lid welded to the second end of the case body and configured to close the second end of the case body that is away from the case bottom.

Description

[Technical field]

[0001] This application claims priority to a Chinese patent application having a filing date of May 26, 2021 and application number 202121145687.X, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of lithium batteries, for example, to a battery case and a lithium battery including the battery case. [Background technology]

[0003] The case of a lithium battery is generally processed and formed by pressing, and in order to reduce the raw material cost of the battery case, the material of the battery case is often stainless steel, but the tensile performance of the stainless steel material is poor, and the pressing depth of the case is greatly limited, and if the shape of the battery case is complicated, the stainless steel material increases the difficulty of pressing the case, so a material with high tensile performance must be used to manufacture the battery case, which greatly increases the manufacturing cost of the lithium battery. The prismatic lithium battery cell in the related art has a high utilization rate in the thickness direction, and the utilization rate at both ends of the lithium battery is relatively low due to the requirements of drawing out the positive and negative electrodes and the need for internal space, and at the same time, the cell expands to one side with a large side area of ​​the winding core during charging and discharging, which causes the battery to have a risk of swelling during subsequent use. Summary of the Invention

[0004] The present application provides a battery case that is easy to process and install.

[0005] The present application further provides a lithium battery with high space utilization and low manufacturing cost.

[0006] One embodiment provides a battery case comprising: a case body having a cylindrical structure with both ends open, and having a first side and a second side that are welded together and provided with a positioning mechanism, the case body being formed by bending and welding a plate material; a case bottom welded to the first end of the case body and configured to close the first end of the case body; and a case lid welded to the second end of the case body and configured to close the second end of the case body that is away from the case bottom.

[0007] One embodiment provides a lithium battery comprising the battery case and a cell located within the case body of the battery case. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a front cross-sectional view of a battery case according to one embodiment of the present application. [Diagram 2] FIG. 2 is a front cross-sectional view of a battery case according to one embodiment of the present application. [Diagram 3] FIG. 2 is a partial cross-sectional plan view of a battery case according to one embodiment of the present application. [Figure 4] FIG. 2 is a front cross-sectional view of a battery case according to one embodiment of the present application. [Diagram 5] FIG. 2 is a schematic plan view of a case body according to an embodiment of the present application. [Figure 6] FIG. 2 is a schematic plan view of a case body according to an embodiment of the present application. [Figure 7] FIG. 2 is a schematic plan view of a case body according to an embodiment of the present application. [Figure 8] FIG. 1 is an assembly schematic diagram of a lithium battery according to an embodiment of the present application. [Figure 9] 1 is a front cross-sectional view of a lithium battery according to an embodiment of the present application. [Figure 10] FIG. 1 is a plan sectional view of a lithium battery according to an embodiment of the present application. [Figure 11] FIG. 2 is a partially enlarged schematic diagram of A in FIG. [Figure 12] FIG. 3 is a partially enlarged schematic view of B in FIG. [Figure 13]FIG. 4 is a partially enlarged schematic view of C in FIG. [Figure 14] 10 is a partially enlarged schematic view of D in FIG. 9. FIG. [Explanation of symbols]

[0009] 100...first core body, 200...second core body, 300...cell tab, REFERENCE SIGNS LIST 1 case body, 11 first side edge, 12 second side edge, 101 protrusion, 102 bump, 103 through hole, 104 first accommodating area, 105 second accommodating area, 106 groove, 110 first step, 120 second step, 2 case bottom, 201 bottom plate, 2011 step surface, 202 surrounding wall, 3 case lid, 301 liquid injection hole, 4 cap, 5 blocking material, 6 insulating material, 7 connection sheet, 701 positive electrode sheet, 702 negative electrode sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As shown in Figures 1 to 5 and 9, the battery case of the present application comprises a case body 1, a case bottom 2 and a case lid 3, the case body 1 has a cylindrical structure that is open at both ends and is formed by bending and welding a plate material, the plate material has a first side edge 11 and a second side edge 12 that are welded together, and the first side edge 11 and the second side edge 12 are provided with positioning mechanisms to assist in welding, the case bottom 2 is welded to a first end of the case body 1 and is configured to close the first end of the case body 1, and the case lid 3 is welded to a second end of the case body 1 and is configured to close the second end of the case body 1 that is away from the case bottom 2. Manufacturing case body 1 by bending and shaping plate material reduces the amount of distortion in the plate material, prevents defects such as cracks from appearing in the plate material, and reduces the difficulty of manufacturing case body 1. By providing a positioning mechanism, the plate material can be temporarily fixed after being bent into a specified position before being welded, reducing the difficulty of welding the plate material and also ensuring the manufacturing precision of case body 1.

[0011] 9, the present application further provides a lithium battery including a cell located in a case body 1 and a battery case according to the above embodiment. The lithium battery has a simple structure and is easy to realize automated production. When the usage space is limited, the cross-sectional shape of the lithium battery can be designed according to actual needs to improve the space utilization rate of the lithium battery, and the case body 1 can be manufactured by bending to reduce the manufacturing difficulty of the lithium battery and ensure the strength and reliability of the lithium battery.

[0012] Referring to Figs. 8 to 10, the present invention is applied to the manufacture of the above-mentioned lithium battery, a step of bending the plate material, aligning the first side edge 11 and the second side edge 12 of the plate material by a positioning mechanism, and welding the plate material to form the case body 1; A step of placing a cell in a case body 1; connecting the negative tab of the cell to the case bottom 2 and the positive tab of the cell to the cap 4 of the case lid 3; and welding the case lid 3 and the case bottom 2 to the case body 1, respectively, and injecting an electrolyte into the battery case.

[0013] The plate materials are first welded together to form the case body 1, and then the cells are inserted. This makes it easier to manufacture the case body 1 and also prevents the heat generated during welding from being transferred to the cells, reducing the impact of welding the battery case on cell performance.

[0014] 1 and 4, in one embodiment, the plate material has a groove 106 on the first side 11, the width of the groove bottom of the groove 106 is larger than the width of the groove mouth of the groove 106, and a protrusion 101 adapted to the shape of the groove 106 is provided on the second side 12. When the first side 11 and the second side 12 contact each other, the protrusion 101 is inserted into the groove 106, realizing temporary fixing before welding of the plate material, and reducing the difficulty of welding the plate material. The groove 106 and the protrusion 101 have a simple structure and are easy to process, which can reduce the manufacturing difficulty of the case body 1, and the engagement between the groove 106 and the protrusion 101 makes the wall thickness at each point of the case body 1 almost the same, which reduces the space occupied by the case body 1 and improves the utilization rate of the internal space of the case body. At this time, the groove 106 and the protrusion 101 are a positioning mechanism for the battery case.

[0015] In this embodiment, a single sheet of plate material is bent, and in this way, the number of times the plate material is welded can be reduced. The number of times the sheet material is bent is at least four. The connection position between the first side edge 11 and the second side edge 12 is located on one side of the case body 1. In this way, not only can the difficulty of welding the plate material be reduced, but also the difficulty of polishing the weld bead after welding can be reduced and the welding efficiency can be improved. Of course, the connection position between the first side edge 11 and the second side edge 12 can also be located at a corner position of the case body 1. At this time, in order to ensure that the protrusion 101 can be inserted into the groove 106, it is necessary to perform a bending process on the protrusion 101. At this time, the number of times the sheet material is bent is at least three. This setting method can reduce the number of times the plate material is bent.

[0016] 2 and 3, in one embodiment, a through hole 103 is provided near the first side 11 of the plate, and a bump 102 is provided near the second side 12 of the plate. After the plate is bent to a predetermined position, the bump 102 is inserted into the through hole 103 to temporarily fix the plate, and at this time, the first side 11 of the plate is overlapped and connected to the outer wall of the plate, and the second side 12 of the plate is overlapped and connected to the inner wall of the plate, that is, there is an area where the plate overlaps on the case body 1, and the first side 11 of the plate and the outer wall of the plate are welded. By adopting the fitting method of the bump 102 and the through hole 103 to temporarily fix the plate, the connection strength of the temporary fixation of the plate can be improved, and the occurrence of deviation of the first side 11 and the second side 12 during the welding period can be avoided, and the manufacturing accuracy of the case body 1 can be improved. At this time, the through holes 103 and the bumps 102 serve as a positioning mechanism for the battery case.

[0017] In this embodiment, a rivet may be provided close to the second side edge 12 of the plate, and after the plate is bent into position, the rivet is inserted into the through hole 103 and then crimped to temporarily fix the plate, thereby improving the connection stability of the temporary fixation of the plate.

[0018] Referring to FIG. 11, in one embodiment, the case bottom 2 has a bottom plate 201, the edge of the bottom plate 201 extends toward one side of the case body 1 to form an enclosing wall 202, and the outer wall of the enclosing wall 202 is connected to the inner wall of the case body 1, so that the outer surface of the case body 1 can be made flush, and the inner wall of the enclosing wall 202 may be connected to the outer wall of the case body 1; referring to FIG. 13, in one embodiment, the case body 1 has a first section 110 and a second section 120, and the cross-sectional size of the second section 120 is smaller than the cross-sectional size of the first section 110, and the case bottom 2 has an inner wall of the enclosing wall 202 connected to the outer wall of the second section 120 of the case body; in this embodiment, the outer surface of the first section 110 and the outer surface of the enclosing wall 202 are engaged and made flush, so that the appearance of the lithium battery can be improved. By providing an overlap structure at the connection position between the case body 1 and the case bottom 2, the sealing performance at the connection position between the case body 1 and the case bottom 2 can be improved. Heat is generated during welding, and the overlap structure enables the battery case to absorb more welding heat, reducing the impact of welding on cell performance.

[0019] In this embodiment, the case bottom 2 is formed by pressing, and the thickness of the case bottom 2 is equal to or greater than the thickness of the plate material of the case body 1. This reduces the probability of press defects appearing in the case bottom 2, and the hardness of the plate material of the case body 1 is greater than the hardness of the case bottom 2. During use, the cells in the lithium battery tend to expand toward one side with a larger side area. At this time, the case body 1, which has a greater hardness, restricts the position of the cells, thereby preventing bulging of the lithium battery.

[0020] In one embodiment, the plate material for manufacturing the case body 1 may be a thin plate such as stainless steel, pure nickel plate, aluminum alloy, or a material that meets the needs of corrosion resistance and weight reduction, for example, a composite material such as aluminum-stainless steel, aluminum-iron-nickel, etc.

[0021] 12, in one embodiment, the case bottom 2 is provided with only a bottom plate 201, and a step surface 2011 is recessed at the periphery of the bottom plate 201, and the step surface 2011 is connected to the case body 1. By providing the step surface 2011, the step surface 2011 and the case body 1 can be positioned during assembly, reducing the difficulty of the subsequent welding work between the two.

[0022] In one embodiment, the case lid 3 is provided with a cap 4 , which is connected to a positive electrode tab of a lithium battery cell, and a negative electrode tab of the lithium battery cell is connected to the case bottom 2 .

[0023] In one embodiment, the cap 4 of the case lid 3 and the case lid 3 are insulated and connected by an insulating material 6, which can prevent the lithium battery from short-circuiting.

[0024] In one embodiment, as shown in Fig. 8 and Fig. 9, the case lid 3 is provided with a liquid injection hole 301 and a blocking material 5, and the blocking material 5 selectively blocks the liquid injection hole 301. By providing the liquid injection hole 301, after welding of the case lid 3 and the case bottom 2 to the case body 1 is completed, an electrolyte can be injected into the battery case, and the sealing of the welding position can be guaranteed. During assembly, liquid is injected into the battery case through the liquid injection hole 301, and after the liquid injection is completed, a chemical conversion treatment is performed, and after the chemical conversion is completed, the blocking material 5 is inserted into the liquid injection hole 301, and the blocking material 5 and the case lid 3 are welded and sealed by a laser welding method.

[0025] 8 and 14, the distance between the case lid 3 and the cell is L1, the length of the cell tab 300 is L2, and L2>L1. By making the length of the cell tab 300 longer than the distance between the case lid 3 and the cell, the cell tab 300 and the cap 4 can be connected in a variety of ways, such as by welding, for example, laser welding, ultrasonic welding, and resistance welding, thereby reducing the manufacturing cost of the lithium battery.

[0026] Referring to Figures 8 to 10, a cell in the lithium battery comprises a first core body 100 and a second core body 200, and the first core body 100 and the second core body 200 are connected by a connecting sheet 7. In this embodiment, the thickness of the first core body 100 is greater than the thickness of the second core body 200, a first storage area 104 and a second storage area 105 are arranged in the case body 1, the first storage area 104 and the second storage area 105 are connected, the thickness of the first storage area 104 is greater than the thickness of the second storage area 105, the first core body 100 is located in the first storage area 104, and the second core body 200 is located in the second storage area 105. In this embodiment, the first core body 100 and the second core body 200 are arranged in parallel, and of course, in other embodiments, the first core body 100 and the second core body 200 may be arranged in series. When processing the case body 1, the plate material can be folded multiple times, so that the cross section of the case body 1 has a combination of different shapes, and the lithium battery can be adapted to different usage spaces. At this time, there are a first accommodation area 104 and a second accommodation area 105 with different thicknesses in the case body 1, and the first core body 100 and the second core body 200 with different thicknesses are correspondingly arranged in the first accommodation area 104 and the second accommodation area 105, so that the electric energy storage capacity of the lithium battery can be improved.

[0027] In this embodiment, the first accommodating area 104 and the second accommodating area 105 are arranged along the width direction of the case body, and in other embodiments, the first accommodating area 104 and the second accommodating area 105 may be arranged along the thickness direction, length direction or other directions of the case body 1 according to actual needs.

[0028] Referring to Figures 5 to 7, the cross section of the case body 1 may be a combination of multiple different shapes, and a third core body, a fourth core body, etc. may be provided within the lithium battery depending on the shape of the case body 1.

[0029] In one embodiment, the connection sheet 7 comprises a positive electrode sheet 701 and a negative electrode sheet 702, the negative electrode tab of the first core body 100 and the negative electrode tab of the second core body 200 are connected by the negative electrode sheet 702, the negative electrode sheet 702 is connected to the case bottom 2, the positive electrode tab of the first core body 100 and the positive electrode tab of the second core body 200 are connected by the positive electrode sheet 701, the length of the positive electrode sheet 701 is greater than the distance between the cell and the case lid 3, and the positive electrode sheet 701 is welded to the cap 4 of the case lid 3. After the welding of the positive electrode sheet 701 and the cap 4 is completed, the case lid 3 and the case body 1 are assembled, positioned and welded.

Claims

1. a case body having a cylindrical structure with both ends open, and having a first side and a second side connected by welding and provided with a positioning mechanism, the case body being formed by bending and welding a plate material; a case bottom welded to a first end of the case body and configured to close the first end of the case body; a case lid welded to a second end of the case body and configured to close a second end of the case body away from the case bottom; The positioning mechanism includes: a through hole provided in the plate material and proximate to the first side edge; a bump provided on the plate member and proximate the second side edge and configured to be inserted into the through hole; The first side is welded to an outer wall of the plate, and the second side is welded to an inner wall of the plate. Battery case.

2. The case bottom includes a bottom plate having an edge extending toward one side of the case body to form a surrounding wall, The outer wall of the surrounding wall is connected to the inner wall of the case body, or the inner wall of the surrounding wall is connected to the outer wall of the case body. The battery case according to claim 1 .

3. the case body includes a first step and a second step; a cross-sectional size of the second step being smaller than a cross-sectional size of the first step; The case bottom includes a bottom plate having an edge extending toward one side of the case body to form a surrounding wall, an inner wall of the enclosure connected to an outer wall of the second stage; The battery case according to claim 1 .

4. At least a first storage area and a second storage area are arranged in the case body, The first storage area and the second storage area are in communication with each other, The thickness of the first storage area is greater than the thickness of the second storage area. The battery case according to claim 1 .

5. At least one of the following is adopted: a thickness of the case bottom is equal to or greater than a thickness of the plate material of the case body; and a hardness of the plate material of the case body is greater than a hardness of the case bottom. The battery case according to claim 1 .

6. The battery case according to any one of claims 1 to 5, A cell located within the case body of the battery case. Lithium battery.

7. The distance between the case lid and the cell is L1, the length of the cell tab is L2, and L2>L1.

7. The lithium battery of claim 6.

8. The cell comprises at least a first core body and a second core body, The first core body and the second core body are connected by a connection sheet, and a thickness of the first core body is greater than a thickness of the second core body, A first storage area and a second storage area are provided in the case body, and a thickness of the first storage area is greater than a thickness of the second storage area, The first core body is located within the first receiving area, and the second core body is located within the second receiving area.

7. The lithium battery of claim 6.

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