An improved sealing structure for the negative electrode end of a lithium battery

Abstract

The present invention discloses an improved lithium battery negative terminal sealing structure, comprising an outer shell, a battery cell, a current collecting sheet, a sealing ring and a bottom cover, etc. The bottom cover is designed as a blind cover or a through cover with a mounting hole; in this way, when the bottom cover is a blind cover, the bottom cover is installed at the end of the outer shell to drive the sealing plug on the inner end face of the bottom cover to directly seal and close the current collecting hole on the current collecting cover; when the bottom cover is a through cover, an outer cover is provided on the outside of the bottom cover to form a conductive structure with the bottom cover, and the outer cover drives the sealing block on the inner end face to simultaneously close the current collecting hole and the mounting hole, or the outer cover directly covers the mounting hole and simultaneously closes the current collecting hole. Obviously, the above structure only improves the bottom cover, and adds a sealing plug or sealing block, an outer cover, etc. that match the bottom cover, that is, the current collecting hole on the current collecting cover is sealed and closed, which does not affect the injection of the lithium battery, and can ensure the excellent performance and reliability of the sealing effect, and the design is also simpler, so it can simplify the production process and better meet the needs of production equipment automation.

Description

Technical Field

[0001] The present invention relates to a sealing structure for the end of a lithium battery, in particular to an improved sealing structure for the negative terminal of a lithium battery. Background Art

[0002] At present, full-tab cylindrical lithium batteries have the advantages of large capacity, fast charging, excellent battery thermal runaway performance, strong internal pressure bearing capacity and easy automated production, thus becoming the mainstream development direction of future batteries. In the production process of lithium batteries, it is often necessary to seal the ends of the shell to form the positive and negative terminals of the lithium battery, and the sealing structure of the negative terminal is very important for the design and production process of lithium batteries. Specifically, the sealing structure of the negative terminal of the lithium battery must meet the performance requirements of the lithium battery, as well as the process requirements and the requirements for realizing the automation of production equipment. However, the traditional sealing structure design of the negative terminal of the lithium battery is too complicated, resulting in the inability to take into account all three of the above requirements. This also makes it impossible for the sealing of the negative terminal of the lithium battery to achieve the best structural state. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an improved lithium battery negative terminal sealing structure with a simple structure, excellent performance, simplified production process and better satisfaction of the automation requirements of production equipment.

[0004] The technical problem of the present invention is achieved through the following technical solutions:

[0005] An improved lithium battery negative terminal sealing structure comprises an outer shell, a battery cell in the outer shell, and a current collecting sheet installed at the end of the outer shell and sealing the battery cell; the current collecting sheet is provided with a liquid injection hole, a bottom cover is provided outside the current collecting sheet, a sealing ring is provided between the current collecting sheet and the bottom cover, and a current collecting cover covering and sealing the liquid injection hole, the current collecting cover is provided with a current collecting hole that is connected with the liquid injection hole; the battery cell, the current collecting sheet, the current collecting cover and the bottom cover form a conductive structure, the bottom cover is a blind cover or a through cover with a mounting hole; the bottom cover is a blind cover, a sealing plug is provided on the inner end face of the bottom cover, and the bottom cover is installed at the end face of the outer shell and drives the sealing plug to directly seal and seal the current collecting hole; the bottom cover is a through cover, an outer cover is provided outside the bottom cover to form a conductive structure with the bottom cover, and a sealing block is provided on the inner end face of the outer cover, the outer cover drives the sealing block to simultaneously seal the current collecting hole and the mounting hole, or the outer cover directly covers the mounting hole and simultaneously seals the current collecting hole.

[0006] The outer circumference of the current collecting piece is provided with an outwardly folded edge, and the outer circumferential surface of the shell is provided with a rolling groove which circumferentially surrounds and presses the folded edge.

[0007] A conical contact seal is formed between the sealing plug and the collecting hole; an explosion-proof hole penetrating along the axis and an explosion-proof valve installed in the explosion-proof hole are provided in the sealing plug, and the explosion-proof hole, the collecting hole and the injection hole are on the same axis.

[0008] The outer end surface of the sealing plug is provided with a drainage ring groove which is circumferentially surrounded by the periphery of the explosion-proof hole, and is also provided with a plurality of drainage branch grooves which are respectively connected to the explosion-proof hole and the drainage ring groove.

[0009] The bottom cover is provided with an explosion-proof valve, which is located above the drainage ring groove or above the drainage branch groove.

[0010] The outer cover directly covers the mounting hole and closes the collecting hole at the same time. The outer end cover of the outer cover is covered outside the bottom cover or the outer end cover of the outer cover is covered outside the collecting cover and is flush with the bottom cover.

[0011] The sealing block is a stepped shaft block formed by coaxially connecting a small cylinder and a large cylinder. The small cylinder of the sealing block seals the collecting hole, and the large cylinder of the sealing block seals the installation hole.

[0012] The large cylinder and the collecting hole are in plane contact sealing.

[0013] The outer circumferential surface of the collecting cover is provided with an outer conical surface, and the outer conical surface and the sealing ring form a conical surface contact seal; the collecting cover and the liquid injection hole are closed by the conical surface contact cover.

[0014] The sealing plug is embedded and fixed on the inner end surface of the bottom cover, and the sealing plug and the bottom cover are on the same axis; the sealing block is embedded and fixed on the inner end surface of the outer cover, and the sealing block and the outer cover are on the same axis.

[0015] Compared with the prior art, the present invention mainly designs the bottom cover to be a blind cover or a through cover with a mounting hole according to actual conditions; in this way, when the bottom cover is designed as a blind cover, a sealing plug can be provided on the inner end face of the bottom cover, and the bottom cover is installed at the end face of the outer shell and drives the sealing plug to directly seal and close the collecting holes on the collecting cover; when the bottom cover is designed as a through cover, an outer cover that forms electrical conductivity with the bottom cover needs to be provided outside the bottom cover, and a sealing block is provided on the inner end face of the outer cover, then the outer cover drives the sealing block to simultaneously close the collecting holes and the mounting holes, or the outer cover directly covers the mounting holes and simultaneously closes the collecting holes. Obviously, compared with the traditional lithium battery negative terminal sealing structure, the above-mentioned improved structure can seal the collecting hole on the collecting cover by simply designing the bottom cover and cooperating with the sealing plug or sealing block, outer cover, etc. on the bottom cover. This does not affect the injection of lithium batteries, but can achieve a better sealing effect while ensuring excellent performance. In addition, the design of the negative terminal sealing structure is also simpler. In addition, the outer circumference of the current collecting sheet is also provided with an outward folded edge, which can make the sealing structure of the current collecting sheet to the battery cell more reliable. The above design structures can simplify the production process and better meet the needs of production equipment automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic cross-sectional view of the first negative terminal sealing structure of the present invention.

[0017] Figure 2 for Figure 1 Enlarged view of point A.

[0018] Figure 3 for Figure 1 Half-section stereogram.

[0019] Figure 4 This is a schematic cross-sectional view of the second negative terminal sealing structure of the present invention.

[0020] Figure 5 for Figure 4 Enlarged view of point B.

[0021] Figure 6 for Figure 5 Schematic diagram of the cross-sectional structure with the bottom cover and sealing block removed.

[0022] Figure 7 for Figure 4 Enlarged view of point C.

[0023] Figure 8 for Figure 4 Half-section stereogram.

[0024] Figure 9 This is a schematic cross-sectional view of the third negative terminal sealing structure of the present invention.

[0025] Figure 10 for Figure 9 Enlarged view of point D.

[0026] Figure 11 Schematic diagram of the cross-sectional structure of the fourth negative terminal sealing structure of the present invention.

[0027] Figure 12 for Figure 11 Enlarged view of point E.

[0028] Figure 13 It is a schematic diagram of the cross-sectional structure of the sealing plug.

[0029] Figure 14 for Figure 13 Left view of .

[0030] Figure 15 for Figure 13 Stereoscopic image.

[0031] Figure 16 It is a schematic diagram of the cross-sectional structure of the sealing block.

[0032] Figure 17 This is a schematic diagram of the cross-sectional structure of one style of collecting cover.

[0033] Figure 18 This is a schematic diagram of the cross-sectional structure of another style of collecting cover. DETAILED DESCRIPTION

[0034] The embodiments of the present invention will be described in detail below with reference to the above-mentioned drawings.

[0035] like Figures 1 to 18 As shown, 1. shell, 11. rolling groove, 2. battery cell, 3. current collecting sheet, 31. injection hole, 32. folding edge, 4. bottom cover, 41. mounting hole, 5. sealing ring, 6. current collecting cover, 61. current collecting hole, 62. inner cone, 63. plane, 64. outer cone, 7. sealing plug, 71. explosion-proof hole, 72. drainage ring groove, 73. drainage branch groove, 8. sealing block, 81. small cylinder, 82. large cylinder.

[0036] An improved lithium battery negative terminal sealing structure, such as Figure 1 、 Figure 4 、 Figure 9 、 Figure 11 As shown, it mainly involves the sealing structure of the negative terminal of a cylindrical lithium battery, which includes a metal cylindrical shell 1, a battery cell 2 arranged in the shell, and a current collector 3 installed at the end of the shell and enclosing the battery cell 2. The current collector is provided with an injection hole 31 to facilitate the injection of electrolyte into the shell 1.

[0037] In addition, the outer circumference of the current collecting sheet 3 is provided with an outward folded edge 32, which can be pressed by the rolling groove 11 arranged in a circumferential manner on the outer circumferential surface of the shell 1. This not only makes the sealing and closing structure of the current collecting sheet 3 to the battery cell 2 more reliable, but also the current collecting sheet 3 with the folded edge 32 is more convenient for transportation and assembly of automated production equipment.

[0038] The collecting sheet 3 is provided with a bottom cover 4 on the outside, and the outer edge of the bottom cover and the inner edge of the end of the shell 1 are fixed into one body mainly through a circumferential curling process. A sealing ring 5 is provided between the collecting sheet 3 and the bottom cover 4 for spacing, and a collecting cover 6 that uses a conical surface contact to cover and seal the injection hole 31. The collecting cover is provided with a collecting hole 61 that is connected to the injection hole 31, and a conical surface contact seal is also adopted between the collecting cover 6 and the sealing ring 5. Specifically, an outer conical surface 64 is provided on the outer circumferential surface of the collecting cover 6, and a conical surface contact seal is formed by the outer conical surface and the sealing ring 5.

[0039] The battery core 2 , current collecting sheet 3 , current collecting cover 6 and bottom cover 4 form a conductive structure so as to draw out the negative current on the bottom cover 4 , and the current collecting cover 6 and the bottom cover 4 are mainly connected by welding.

[0040] The bottom cover 4 is a blind cover or a through cover with a mounting hole 41; wherein, if the bottom cover 4 is a blind cover, that is, Figures 1 to 3 In the first negative terminal sealing structure shown, the inner end surface of the bottom cover 4 needs to be provided with an embedded and fixed sealing plug 7, and the sealing plug 7 and the bottom cover 4 are exactly on the same axial line. When the bottom cover 4 is installed at the end of the shell 1, it will drive the sealing plug 7 to directly seal and close the collecting hole 61.

[0041] At the same time, the sealing plug 7 and the manifold 61 are mainly sealed by a conical contact, that is, Figure 17 As shown, the collecting hole 61 is a tapered hole with a larger outside and a smaller inside, and the sealing plug 7 is a tapered plug with a larger outside and a smaller inside. The sealing plug 7 can make circumferential contact and seal with the inner conical surface 62 of the collecting hole 61 through the conical outer circumferential surface. Such a shape design can better improve the sealing performance of the sealing plug 7; therefore, the bottom cover 4 and the sealing plug 7 can form a whole and be sealed and installed at the end of the outer shell 1, thereby forming a negative terminal sealing structure with a reliable sealing effect.

[0042] The sealing plug 7 is as follows Figures 13 to 15 As shown, the sealing plug 7 is provided with an explosion-proof hole 71 that passes through along the axial line, so the explosion-proof hole, the collecting hole 61 and the injection hole 31 are all on the same axial line, and an explosion-proof valve is provided in the explosion-proof hole 71 to play the first safety protection role; the outer end face of the sealing plug 7 is provided with a drainage ring groove 72 that is circumferentially surrounded by the outer periphery of the explosion-proof hole 71, and is also provided with a number of drainage branch grooves 73 that are respectively connected to the explosion-proof hole 71 and the drainage ring groove 72. In this embodiment, a total of four drainage branch grooves 73 distributed in a cross shape are designed.

[0043] In this way, the airflow leaking in the shell 1 can be diverted and pressure-relieved through several drainage branch grooves 73 and drainage ring grooves 72; and, an explosion-proof valve can also be provided on the bottom cover 4, which is located above the drainage ring groove 72 or above the drainage branch groove 73, mainly serving as a second line of safety protection.

[0044] Obviously, the explosion-proof valve in the sealing plug 7 and the explosion-proof valve on the bottom cover 4 can both play a role in safety and explosion prevention, thereby better ensuring the safety of the lithium battery.

[0045] If the bottom cover 4 is a through cover, an outer cover 9 is required outside the bottom cover 4, and the outer cover is mainly divided into three types of closed structures, namely Figures 4 to 8 The second negative terminal sealing structure shown is provided with a sealing block 8 embedded and fixed on the inner end surface of the outer cover 9. The sealing block 8 and the outer cover 9 are exactly on the same axial line. The outer cover 9 drives the sealing block 8 to simultaneously seal the collecting hole 61 and the mounting hole 41, and a conductive connection can also be formed between the outer cover 9 and the bottom cover 4 to draw out the negative electrode current on the outer cover 9. The two are mainly connected by welding.

[0046] Among them, the sealing block 8 is as follows Figure 16 As shown, a stepped shaft block is formed by a small cylinder 81 and a large cylinder 82 coaxially connected, and the small cylinder 81 of the sealing block 8 can be used to seal the collecting hole 61, and the large cylinder 82 of the sealing block 8 can be used to seal the mounting hole 41.

[0047] In addition, when the sealing block 8 is used for sealing, the collecting hole 61 and the mounting hole 41 are as follows. Figure 18 The holes shown are all cylindrical holes, and the large cylinder 82 and the collecting hole 61 are in contact and sealed with the plane 63.

[0048] and Figure 9 、 Figure 10 The third negative terminal sealing structure is shown. Figure 11 、 Figure 12 The fourth negative terminal sealing structure is shown. Both of these negative terminal sealing structures do not have a sealing block 8, that is, the outer cover 9 directly covers the mounting hole 41 and closes the collecting hole 61 at the same time. Specifically, a sinking structure is provided in the middle of the outer cover 9, and the sinking structure extends into the mounting hole 41 and the collecting hole 61 in turn, thereby covering the mounting hole 41 and closing the collecting hole 61 at the same time.

[0049] In addition, the third negative terminal sealing structure is that the outer end cover of the outer cover 9 is closed on the outside of the bottom cover 4, and the outer cover needs to be welded and conductively connected to the bottom cover 4 to form conductivity between the outer cover 9 and the bottom cover 4, thereby drawing out the negative current on the outer cover 9; the fourth negative terminal sealing structure is that the outer end cover of the outer cover 9 is closed on the outside of the current collecting cover 6 and is flush with the bottom cover 4, and the outer cover needs to be welded and conductively connected to the current collecting cover 6 to form conductivity between the outer cover and the current collecting cover, thereby also drawing out the negative current on the outer cover 9; therefore, the use of these two specially designed outer covers is mainly to facilitate the automated transportation, grasping and assembly of the outer cover 9.

[0050] Of course, whether it is the sealing plug 7 involved in the first negative terminal sealing structure or the sealing block 8 involved in the second negative terminal sealing structure, they both have another function, which is to isolate the electrolyte in the outer shell 1 from the metal bottom cover 4 to prevent the electrolyte from directly contacting the bottom cover 4. Therefore, while playing a sealing role, it can also prevent the bottom cover 4 from being corroded due to direct contact with the electrolyte, thereby affecting the performance of the lithium battery.

[0051] Compared with the traditional lithium battery negative terminal sealing structure, the improved structure of the present invention can seal the collecting hole 61 on the collecting cover 6 only by designing the bottom cover 4 and cooperating with the sealing plug 7 or sealing block 8, outer cover 9, etc. on the bottom cover 4. It does not affect the injection of lithium batteries and can achieve a better sealing effect on the basis of ensuring excellent performance. Moreover, the design of the negative terminal sealing structure is also simpler, so it can simplify the production process and better meet the needs of production equipment automation.

[0052] The above description is only a specific embodiment of the present invention. Those skilled in the art should understand that any structural design similar to this embodiment should be included in the protection scope of the present invention.

Claims

1. An improved lithium battery negative terminal sealing structure, comprising a shell (1), a battery cell (2) in the shell, and a current collecting sheet (3) mounted at the end of the shell and enclosing the battery cell (2); the current collecting sheet is provided with a liquid injection hole (31), a bottom cover (4) is provided outside the current collecting sheet, a sealing ring (5) is provided between the current collecting sheet (3) and the bottom cover (4), and a current collecting cover (6) covering and sealing the liquid injection hole (31), the current collecting cover is provided with a current collecting hole (61) intersecting the liquid injection hole (31); the battery cell (2), the current collecting sheet (3), the current collecting cover (6) and the bottom cover (4) form a conductive structure, characterized in that: The bottom cover (4) is a blind cover or a through cover with a mounting hole (41); When the bottom cover (4) is a blind cover, a sealing plug (7) is provided on the inner end surface of the bottom cover, and the bottom cover (4) is installed at the end of the shell (1) and drives the sealing plug (7) to directly seal and close the collecting hole (61); a conical contact seal is formed between the sealing plug (7) and the collecting hole (61); an explosion-proof hole (71) extending along the axis and an explosion-proof valve installed in the explosion-proof hole are provided in the sealing plug (7), and the explosion-proof hole (71), the collecting hole (61) and the injection hole (31) are on the same axis; an outer conical surface (64) is provided on the outer circumferential surface of the collecting cover (6), and the outer conical surface forms a conical contact seal with the sealing ring (5); the collecting cover (6) and the injection hole (31) are closed by a conical contact cover; When the bottom cover (4) is a through cover, the bottom cover (4) is provided with an outer cover (9) that forms a conductive connection with the bottom cover (4), and a sealing block (8) is provided on the inner end surface of the outer cover (9), and the outer cover (9) drives the sealing block (8) to simultaneously close the collecting hole (61) and the mounting hole (41), or the outer cover directly covers the mounting hole (41) and simultaneously closes the collecting hole (61); the outer cover (9) directly covers the mounting hole (41) and simultaneously closes the collecting hole (61), the outer end cover of the outer cover (9) is closed on the outside of the bottom cover (4), or the outer end cover of the outer cover (9) is closed on the outside of the collecting cover (6) and is flush with the bottom cover (4); the sealing block (8) is a stepped shaft block formed by a small cylinder (81) and a large cylinder (82) coaxially connected, and the small cylinder (81) of the sealing block (8) seals and closes the collecting hole (61), and the large cylinder (82) of the sealing block (8) seals and closes the mounting hole (41).

2. The improved lithium battery negative terminal sealing structure according to claim 1, characterized in that The outer circumference of the current collecting piece (3) is provided with an outwardly folded edge (32), and the outer circumferential surface of the housing (1) is provided with a rolling groove (11) that circumferentially surrounds and presses the folded edge (32).

3. The improved lithium battery negative terminal sealing structure according to claim 1, characterized in that The outer end surface of the sealing plug (7) is provided with a drainage annular groove (72) circumferentially surrounding the periphery of the explosion-proof hole (71), and is also provided with a plurality of drainage branch grooves (73) respectively communicating with the explosion-proof hole (71) and the drainage annular groove (72).

4. The improved lithium battery negative terminal sealing structure according to claim 3, characterized in that The bottom cover (4) is provided with an explosion-proof valve, which is located above the drainage ring groove (72) or above the drainage branch groove (73).

5. The improved lithium battery negative terminal sealing structure according to claim 1, characterized in that The large cylinder (82) and the collecting hole (61) are in contact and sealed with a plane (63).

6. The improved lithium battery negative terminal sealing structure according to claim 1, characterized in that The sealing plug (7) is embedded and fixed on the inner end surface of the bottom cover (4), and the sealing plug (7) and the bottom cover (4) are on the same axis; the sealing block (8) is embedded and fixed on the inner end surface of the outer cover (9), and the sealing block (8) and the outer cover (9) are on the same axis.

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