Battery monomer and battery pack

Abstract

The invention relates to the technical field of new energy batteries, and discloses a single battery and a battery pack, the single battery has a first direction, the single battery comprises a shell, and the shell is provided with an accommodating cavity and a pole hole; the electrode assembly is arranged in the accommodating cavity; the pole assembly comprises a pole body, a welding table and a fixing ring, the pole body is arranged in the pole hole, the pole body is electrically connected with the pole assembly, the welding table comprises a first section and a second section, the pole body and the fixing ring are welded and fixed to the first section, and the first section is in a first direction; the fixing ring and the second section are located on the two sides of the shell respectively and are in stopping fit with the shell in the first direction. The bottom plate is welded and fixed with the shell, and the bottom plate is provided with a pressure relief device; and the explosion-proof valve seals the pressure relief hole. The welding seam is positioned on one side, close to the anti-explosion valve, of the battery monomer, so that the risk of cracking and impacting the welding seam is low; in addition, no welding seam connection exists between the pole assembly and the shell, the tearing risk is low, and the safety of the single battery is improved.

Description

Technical Field

[0001] The present application relates to the technical field of new energy batteries, and in particular to a battery cell and a battery pack. Background Art

[0002] During use, lithium-ion batteries can experience thermal runaway, generating high-temperature, high-pressure materials. Lithium-ion batteries are typically equipped with explosion-proof valves. When the gas pressure inside the battery reaches the valve's opening pressure, the gas pushes through the valve to release the pressure. There are various locations for the explosion-proof valve on lithium-ion batteries. Designing the explosion-proof valve on the opposite side of the terminal allows for rapid, directional pressure relief, minimizing the impact of thermal runaway spray on other cells within the battery pack and improving the safety of the battery pack in the event of an anomaly.

[0003] Existing lithium-ion batteries consist of an outer shell and a top cover. The explosion-proof valve is located at the bottom of the outer shell, and the terminal body is located on the top cover. The top cover and outer shell are welded together. Because a large amount of gas is generated in a short period of time within the lithium-ion battery, when the explosion-proof valve is opened to release pressure, the gas that is not discharged in time will accumulate in the battery. The strength of the weld on the outer shell is lower than that of the integrally molded part. Therefore, when the pressure inside the battery is high, the gas will first break through the weak weld between the outer shell and the cover, causing the top cover to be blown open, posing a safety risk. Summary of the Invention

[0004] The purpose of the present application is to provide a battery cell to solve the problem in the prior art that the top cover of a lithium-ion battery is impacted and opened during thermal runaway; the present application also provides a battery pack using the battery cell.

[0005] In order to achieve the above object, the present application provides a battery cell, wherein the battery cell has a first direction and comprises

[0006] A housing is provided with a communicating accommodation cavity and a pole hole, wherein the pole hole penetrates the housing along the first direction;

[0007] an electrode assembly, disposed in the accommodating cavity;

[0008] A pole assembly, the pole assembly comprising a pole body, a welding platform, and a fixing ring, the pole body being disposed in the pole hole and electrically connected to the electrode assembly, the welding platform comprising a first section and a second section connected thereto, the pole body and the fixing ring being fixedly connected to the first section, the fixing ring and the second section being respectively located on either side of the housing along the first direction and respectively engaging with the housing in a stoppered manner along the first direction;

[0009] a bottom plate, the bottom plate being fixedly connected to the housing, the bottom plate sealing the accommodating cavity, the bottom plate being provided with a pressure relief hole, the pressure relief hole penetrating the bottom plate along the first direction;

[0010] An explosion-proof valve is fixedly connected to the bottom plate, and the explosion-proof valve seals the pressure relief hole.

[0011] In some embodiments, the pole assembly further includes a first insulating member and a second insulating member, wherein the first insulating member is sandwiched between the fixing ring and the housing, and the second insulating member is sandwiched between the second section and the housing.

[0012] In some embodiments, the pole assembly further includes a sealing ring disposed between the housing and the first section.

[0013] In some embodiments, an end of the first section of the welding platform away from the second section is provided with a convex edge facing away from the fixing ring, and the pole body has a boss extending toward the first section, and the convex edge is fixed to the boss by welding.

[0014] In some embodiments, the battery cell further includes a plastic bracket, the plastic bracket being disposed in the accommodating cavity, the plastic bracket being located between the housing and the electrode assembly, the plastic bracket being provided with a central hole, the central hole penetrating the plastic bracket along the first direction;

[0015] The shell is further provided with a liquid injection hole, which penetrates the shell along the first direction, and the liquid injection hole and the central hole are arranged opposite to each other along the first direction.

[0016] In some embodiments, the battery cell further includes protective tape, the protective tape is adhered to a side of the plastic bracket facing the electrode assembly along the first direction, and the protective tape seals the central hole.

[0017] In some embodiments, the battery cell further includes a protective tape, which is adhered to the electrode assembly. Along the first direction, the protective tape is arranged opposite to the center hole.

[0018] In some embodiments, the bottom plate is further provided with a step surface at an edge, and the step surface is fixedly connected to the shell.

[0019] In some embodiments, the battery cell further includes an outer envelope, which is coated on the outer shell and the bottom plate, and the outer envelope is provided with windows corresponding to the outer shell and / or the bottom plate.

[0020] The present application also provides a battery pack comprising the battery cells described in any of the above technical solutions.

[0021] Compared with the prior art, the battery cell and battery pack of the embodiment of the present application have the following advantages: the battery cell is formed by an outer shell and a base plate, the outer shell is an integrally formed structure, and the need for a top cover welded to the outer shell is omitted; the explosion-proof valve is arranged on the base plate, and the weld between the base plate and the outer shell is located on the side of the battery cell close to the explosion-proof valve. When the explosion-proof valve is exhausted, the pressure at the weld is small, and the risk of the weld cracking due to impact is low; in addition, the fixing ring and the outer shell, and the second section of the welding table and the outer shell are all fitted with stops along the first direction, and there is no weld connection between the pole assembly and the outer shell. When impacted by high-pressure gas, the stop fit has higher strength, and the risk of tearing at the connection between the pole assembly and the outer shell is low, thereby improving the safety of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the battery cell of the present application;

[0023] Figure 2 yes Figure 1 A structural diagram of a battery cell from another perspective;

[0024] Figure 3 yes Figure 1 A cross-sectional view of a battery cell;

[0025] Figure 4 yes Figure 3 A partial enlarged schematic diagram of the battery cell A;

[0026] Figure 5 yes Figure 3 A partial enlarged schematic diagram of the battery cell B;

[0027] Figure 6 yes Figure 1 A schematic structural diagram of a battery cell shell;

[0028] Figure 7 yes Figure 6 A schematic structural diagram of the shell from another perspective;

[0029] Figure 8 yes Figure 2 A schematic structural diagram of a bottom plate of a battery cell;

[0030] Figure 9 yes Figure 8 A partial enlarged schematic diagram of the bottom plate C;

[0031] Figure 10 yes Figure 8 A partial enlarged schematic diagram of the assembly of the bottom plate and the shell;

[0032] Figure 11 yes Figure 3 A schematic diagram of the structure of a plastic bracket of a battery cell;

[0033] Figure 12 yes Figure 11 A structural diagram of the plastic bracket from another perspective;

[0034] Figure 13 This is a schematic diagram of the connection between the electrode assembly and the connecting piece of the battery cell of the present application.

[0035] In the figure, 1. shell, 11. side plate, 12. top plate, 13. accommodating cavity, 14. pole hole, 15. injection hole, 2. electrode assembly, 21. pole ear, 3. pole assembly, 31. pole body, 323. convex edge, 32. welding platform, 321. first section, 322. second section, 311. boss, 33. fixing ring, 34. first insulating member, 35. second insulating member, 36. sealing ring, 37. connecting piece, 4. bottom plate, 41. pressure relief hole, 42. step surface, 5. explosion-proof valve, 6. plastic bracket, 61. center hole, 7. patch, 8. protective tape, 9. outer film, 91. window, Z, first direction. DETAILED DESCRIPTION

[0036] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0037] A preferred embodiment of a battery cell of the present application is as follows: Figures 1 to 13 As shown, the battery cell includes a shell 1, an electrode assembly 2, a pole assembly 3, a bottom plate 4 and an explosion-proof valve 5. The battery cell has a first direction Z. In this embodiment, the battery cell is a square battery, and the first direction Z is the height direction of the battery cell.

[0038] like Figure 1 、 Figure 2 、 Figure 6 and Figure 7 As shown, the housing 1 includes side panels 11 and a top panel 12. The side panels 11 and the top panel 12 are integrally formed, and there is no weld between the side panels 11 and the top panel 12 to avoid a weak point at the connection between the top panel 12 and the side panels 11. The housing 1 is provided with a communicating accommodating cavity 13 and a pole hole 14. The accommodating cavity 13 is surrounded by the side panels 11 and the top panel 12. The pole hole 14 extends through the top panel 12 of the housing 1 along a first direction Z. The electrode assembly 2 is disposed in the accommodating cavity 13, and the pole assembly 3 is at least partially disposed in the pole hole 14.

[0039] In this embodiment, there are two pole holes 14, and the two pole holes 14 are spaced apart along the width direction of the battery cell. There are also two pole assemblies 3, and the pole assemblies 3 correspond to the pole holes 14 one by one. The two pole assemblies 3 respectively form the positive and negative poles of the battery cell. Except for the material, the other structures of the two pole assemblies 3 are the same. Only one is used as an example here for illustration.

[0040] like Figure 3 and Figure 4 As shown, the pole assembly 3 includes a pole body 31, a welding platform 32 and a fixing ring 33. The pole body 31 is arranged in the pole hole 14 and is electrically connected to the electrode assembly 2. Figure 13 As shown, the electrode assembly 2 has a tab 21, and the pole assembly 3 further includes a connecting piece 37. One end of the connecting piece 37 is welded to the tab 21 by ultrasonic welding, and the other end of the connecting piece 37 is welded to the pole body 31 by laser welding. The connecting piece 37 and the tab 21 electrically connect the pole body 31 to the electrode assembly 2. In this embodiment, the negative pole body 31 is made of an aluminum-copper composite material, and the positive pole body 31 is made of aluminum.

[0041] like Figure 4 As shown, the welding platform 32 includes a first section 321 and a second section 322 connected to the first section 321. The first section 321 is sleeved on the pole body 31 and is welded to the pole body 31 to fix the pole body 31 using the welding platform 32. The fixing ring 33 is sleeved on the outside of the first section 321 and is welded to the first section 321. That is, the inner ring of the first section 321 is welded to the pole body 31, and the outer ring is welded to the fixing ring 33. As a result, the pole body 31, the welding platform 32, and the fixing ring 33 form a stable integral structure.

[0042] The second section 322 is located at one end of the first section 321, closer to the electrode assembly 2, along the first direction Z. The second section 322 and the first section 321 form an integral structure. Along the first direction Z, the fixing ring 33 and the second section 322 are located on either side of the housing 1. The second section 322 is located on the lower side of the housing 1, while the fixing ring 33 is located on the upper side of the housing 1. The fixing ring 33 and the housing 1 are engaged in a stop along the first direction Z, and the second section 322 and the housing 1 are engaged in a stop along the first direction Z.

[0043] After the terminal assembly 3 is assembled to the housing 1, it is secured by the stopper assembly between the fixing ring 33, the second section 322, and the housing 1, preventing the terminal assembly 3 from moving in the first direction Z. No welding is required between the terminal assembly 3 and the housing 1, resulting in no weld seam on the side of the housing 1 facing away from the base plate 4. Compared to welding, the stopper assembly provides higher assembly strength, minimizing the risk of tearing between the terminal assembly 3 and the housing 1 in the event of thermal runaway of the battery body.

[0044] like Figure 2 、 Figure 8As shown, the bottom plate 4 is welded to the outer shell 1 and seals the accommodating chamber 13. The bottom plate 4 is provided with a pressure relief hole 41, which extends through the bottom plate 4 along the first direction Z. The explosion-proof valve 5 is fixedly connected to the bottom plate 4 and seals the pressure relief hole 41. In the event of thermal runaway of the battery, high-pressure gas can impact the explosion-proof valve 5 to release pressure. The bottom plate 4 is welded to the outer shell 1 to form a weld. The weld and the explosion-proof valve 5 are located on the same side. When the explosion-proof valve 5 is vented, the pressure at the weld is relatively low, and the risk of the weld cracking due to impact is low.

[0045] The battery cell of the battery cell is formed by an outer shell 1 and a base plate 4. The outer shell 1 is an integrally formed structure, and the additional top cover welded to the outer shell 1 is omitted. The explosion-proof valve 5 is arranged on the base plate 4, and the weld between the base plate 4 and the outer shell 1 is located on the side of the battery cell close to the explosion-proof valve 5. When the explosion-proof valve 5 is exhausted, the pressure at the weld is small, and the risk of the weld cracking due to impact is low; in addition, the fixing ring 33 and the outer shell 1, and the second section 322 of the welding table 32 and the outer shell 1 are all matched along the first direction Z stopper, and there is no weld connection between the pole assembly 3 and the outer shell 1. When impacted by high-pressure gas, the stopper match has higher strength, and the risk of tearing at the connection between the pole assembly 3 and the outer shell 1 is low, thereby improving the safety of the battery cell.

[0046] In some embodiments, the pole assembly 3 further includes a first insulating member 34 and a second insulating member 35 . The first insulating member 34 is sandwiched between the fixing ring 33 and the housing 1 , and the second insulating member 35 is sandwiched between the second section 322 and the housing 1 .

[0047] like Figure 4 As shown, a first insulating member 34 is disposed between the retaining ring 33 and the outer shell 1. The first insulating member 34 insulates the upper side of the outer shell 1 from the retaining ring 33. A second insulating member 35 is disposed between the second section 322 and the outer shell 1. The second insulating member 35 insulates the lower side of the outer shell 1 from the second section 322 of the welding platform 32. The first and second insulating members 34, 35 insulate the entire pole assembly 3 from the outer shell 1, ensuring the insulation and stability of the battery cell. In other embodiments, an insulating coating may also be provided on the retaining ring 33 and the welding platform 32, or at corresponding locations on the outer shell 1, to provide insulation between the pole assembly 3 and the outer shell 1.

[0048] In some embodiments, the pole assembly 3 further includes a sealing ring 36 , which is disposed between the housing 1 and the first section 321 .

[0049] A sealing ring 36 is provided between the first section 321 and the housing 1 . The sealing ring 36 can enhance the sealing between the pole assembly 3 and the housing 1 , and prevent the electrolyte in the accommodating cavity 13 from leaking from the pole hole 14 .

[0050] In some embodiments, the first section 321 of the welding platform 32 has a flange 323 at one end away from the second section 322 , which is away from the fixing ring 33 . The pole body 31 has a boss 311 extending toward the first section 321 . The flange 323 is welded to the boss 311 .

[0051] A convex edge 323 is provided on the first section 321, and a boss 311 is provided on the pole body 31. In this embodiment, the convex edge 323 and the boss 311 overlap along the first direction Z, and the convex edge 323 is located on the upper side of the boss 311. The convex edge 323 and the boss 311 can increase the contact area of ​​the welding point and enhance the welding strength.

[0052] like Figure 3 、 Figure 5 and Figure 11 As shown, in some embodiments, the battery cell further includes a plastic bracket 6, which is disposed in the accommodating cavity 13, and the plastic bracket 6 is located between the outer shell 1 and the electrode assembly 2. The plastic bracket 6 is provided with a center hole 61, and the center hole 61 passes through the plastic bracket 6 along the first direction Z; the outer shell 1 is further provided with an injection hole 15, and the injection hole 15 passes through the outer shell 1 along the first direction Z, and the injection hole 15 and the center hole 61 are arranged opposite to each other along the first direction Z.

[0053] A plastic support 6 is disposed between the housing 1 and the electrode assembly 2. The plastic support 6 insulates the electrode assembly 2 from the housing 1, enhancing the insulation between the housing 1 and the electrode assembly 2. A central hole 61 of the plastic support 6 is disposed opposite the injection hole 15 along the first direction Z. The central hole 61 allows for the plastic pin to be avoided, preventing the plastic support 6 from interfering with the insertion of the plastic pin when the electrolyte is injected into the accommodating cavity 13.

[0054] In this embodiment, the battery body further includes a patch 7 , which is attached to the top plate 12 of the housing 1 . The patch 7 has a clearance hole for avoiding the unit components. The patch 7 can protect the liquid injection hole 15 on the housing 1 .

[0055] In some embodiments, the battery cell further includes a protective tape 8 , which is adhered to a side of the plastic bracket 6 along the first direction Z facing the electrode assembly 2 , and the protective tape 8 seals the central hole 61 .

[0056] like Figure 12 As shown, a protective tape 8 is provided on the side of the plastic bracket 6 facing the electrode assembly 2. When the electrolyte is injected into the accommodating cavity 13, the electrolyte is first flushed onto the protective tape 8, which can prevent the electrolyte from directly flushing the electrode assembly 2 and causing damage to the electrode assembly 2.

[0057] In some embodiments, the battery cell further includes a protective tape 8 , which is adhered to the electrode assembly 2 . Along the first direction Z, the protective tape 8 is disposed opposite to the central hole 61 .

[0058] In this embodiment, the protective tape 8 is pasted on the electrode assembly 2 and is arranged opposite to the center hole 61 along the first direction Z. When the electrolyte is injected into the accommodating cavity 13, the electrolyte is flushed onto the protective tape 8 along the first direction Z, which can prevent the electrolyte from directly flushing the electrode assembly 2 and causing damage to the electrode assembly 2.

[0059] In some embodiments, the bottom plate 4 is further provided with a step surface 42 at the edge, and the step surface 42 is fixedly connected to the housing 1 .

[0060] like Figure 9 and Figure 10 As shown, a step surface 42 is provided on the bottom plate 4 , and the step surface 42 is welded and fixed to the shell 1 , which can increase the contact area and welding strength between the bottom plate 4 and the shell 1 , and also increase the sealing between the bottom plate 4 and the shell 1 .

[0061] In some embodiments, the battery cell further includes an outer film 9 , which covers the outer shell 1 and the bottom plate 4 . The outer film 9 is provided with a window 91 corresponding to the outer shell 1 and / or the bottom plate 4 .

[0062] The outer film 9 can protect the outer shell 1 and the bottom plate 4 of the battery cell. The outer film 9 is provided with a window 91 at a position opposite to the outer shell 1 and the bottom plate 4. The window 91 can expose the metal surface of the outer shell 1 and the bottom plate 4, and can increase the bonding strength with the structural adhesive when the battery cell is assembled into the battery pack.

[0063] The working process of this application is as follows: when assembling the battery cell, the connecting piece 37 is ultrasonically welded to the pole ear 21 of the electrode assembly 2, and then the connecting piece 37 is laser welded to the pole body 31 of the pole assembly 3; the protective tape 8 is pasted on the center hole 61 of the plastic bracket 6, and then the plastic bracket 6 with the protective tape 8 is assembled on the top of the electrode assembly 2, and the electrode assembly 2 is covered with an insulating film, and the insulating film and the plastic bracket 6 are hot-melt fixed; the above-mentioned structure is placed as a whole from bottom to top in the accommodating cavity 13 of the shell 1, and the pole body 31 is passed through the pole hole 14 along the first direction Z, and the first section 321 of the welding platform 32 is welded to the fixing ring 33, so that the pole assembly 3 and the shell 1 form a stable assembly; finally, the bottom plate 4 with the explosion-proof valve 5 is welded to the shell 1 and encapsulated with the outer film 9.

[0064] The present application also provides a preferred embodiment of a battery pack, including a battery cell. The specific structure of the battery cell is the same as the specific structure of the battery cell described in any of the above technical solutions, and will not be repeated here.

[0065] In summary, the embodiments of the present application provide a battery cell and a battery pack, wherein the battery cell is formed by an outer shell and a base plate, the outer shell is an integrally formed structure, and the additional top cover welded to the outer shell is omitted; the explosion-proof valve is arranged on the base plate, and the weld between the base plate and the outer shell is located on the side of the battery cell close to the explosion-proof valve. When the explosion-proof valve is exhausted, the pressure at the weld is small, and the risk of the weld cracking due to impact is low; in addition, the fixing ring and the outer shell, and the second section of the welding table and the outer shell are all fitted with stops along the first direction, and there is no weld connection between the pole assembly and the outer shell. When impacted by high-pressure gas, the strength of the stop fit is higher, and the risk of tearing at the connection between the pole assembly and the outer shell is low, thereby improving the safety of the battery cell.

[0066] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and replacements can be made without departing from the technical principles of the present application. These improvements and replacements should also be regarded as the scope of protection of the present application.

Claims

1. A battery cell, characterized in that: The battery cell has a first direction, and the battery cell includes A housing is provided with a communicating accommodation cavity and a pole hole, wherein the pole hole penetrates the housing along the first direction; an electrode assembly, disposed in the accommodating cavity; A pole assembly, the pole assembly comprising a pole body, a welding platform, and a fixing ring, the pole body being disposed in the pole hole and electrically connected to the electrode assembly, the welding platform comprising a first section and a second section connected thereto, the pole body and the fixing ring being fixedly connected to the first section, the fixing ring and the second section being respectively located on either side of the housing along the first direction and respectively engaging with the housing in a stoppered manner along the first direction; a bottom plate, the bottom plate being fixedly connected to the housing, the bottom plate sealing the accommodating cavity, the bottom plate being provided with a pressure relief hole, the pressure relief hole penetrating the bottom plate along the first direction; An explosion-proof valve is fixedly connected to the bottom plate, and the explosion-proof valve seals the pressure relief hole.

2. The battery cell according to claim 1, wherein: The pole assembly further includes a first insulating member and a second insulating member. The first insulating member is sandwiched between the fixing ring and the shell, and the second insulating member is sandwiched between the second section and the shell.

3. The battery cell according to claim 2, characterized in that: The pole assembly further includes a sealing ring, which is arranged between the shell and the first section.

4. The battery cell according to any one of claims 1 to 3, characterized in that: An end of the first section of the welding platform away from the second section is provided with a convex edge facing away from the fixing ring, and the pole body has a boss extending toward the first section, and the convex edge is fixed to the boss by welding.

5. The battery cell according to any one of claims 1 to 3, characterized in that: The battery cell further includes a plastic bracket, the plastic bracket being disposed in the accommodating cavity, the plastic bracket being located between the housing and the electrode assembly, the plastic bracket being provided with a central hole, the central hole penetrating the plastic bracket along the first direction; The shell is further provided with a liquid injection hole, which penetrates the shell along the first direction, and the liquid injection hole and the central hole are arranged opposite to each other along the first direction.

6. The battery cell according to claim 5, characterized in that The battery cell further includes a protective tape, which is adhered to a side of the plastic bracket facing the electrode assembly along the first direction, and the protective tape seals the central hole.

7. The battery cell according to claim 5, characterized in that The battery cell further includes a protective tape, which is adhered to the electrode assembly. Along the first direction, the protective tape is arranged opposite to the central hole.

8. The battery cell according to any one of claims 1 to 3, characterized in that: The bottom plate is further provided with a step surface at the edge, and the step surface is fixedly connected to the shell.

9. The battery cell according to any one of claims 1 to 3, characterized in that: The battery cell further includes an outer film, which is coated on the outer shell and the bottom plate. The outer film is provided with windows corresponding to the outer shell and / or the bottom plate.

10. A battery pack, characterized in that: The battery cell comprises the battery cell according to any one of claims 1 to 9.

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