Cylindrical battery

Abstract

A cylindrical battery, characterized in that it comprises a casing and a jelly roll, the jelly roll being positioned within the casing and the jelly roll having a jelly roll hole; the cylindrical battery also comprises a pressure relief structure and a current collector, the pressure relief structure and the current collector being provided at two ends of the casing in the axial direction, the current collector being electrically connected to a tab extending from the jelly roll, the current collector comprising a protrusion portion configured to be electrically connected to a pole piece assembly of the cylindrical battery, the protrusion portion having a chamber communicating with the jelly roll hole, the distance between the surface of the protrusion portion facing the jelly roll and the end surface of the negative electrode of the jelly roll facing the current collector is "h" in units of mm;is the radial dimension of the jelly-roll hole “D” in units of mm; where h / D = 0.2 to 1.8;

Description

TECHNICAL FIELD

[0001] The present utility model relates to the technical field of batteries or accumulators, in particular to a cylindrical battery. BACKGROUND

[0002] Currently, when a cylindrical battery undergoes thermal runaway, venting fails to occur in a timely manner, resulting in the accumulation of flammable gas inside the battery and causing an explosion. This can destroy the integrity of the battery and is not conducive to thermal management of the entire battery pack, thus compromising the safety of the entire battery pack.

[0003] Under the design condition that the explosion-proof valve structure of the cylindrical battery tends to be uniform, how to reasonably design the vent channel inside the cylindrical battery to ensure the integrity of the cylindrical battery's state during thermal runaway has become a technical problem that professionals currently need to solve. SUMMARY OF THE UTILITY MODEL

[0004] The object of the present application is to provide a cylindrical battery. The rational design of the vent channel allows the gas accumulated on the current collector side during thermal runaway to be smoothly discharged to the pressure relief structure side, thus contributing to ensuring the integrity of the cylindrical battery.

[0005] To solve the above-mentioned technical problems, the present application provides a cylindrical battery including a case and a jelly roll, the jelly roll being positioned within the case and the jelly roll having a jelly roll hole;The cylindrical battery also includes a pressure relief structure and a current collector. The pressure relief structure and the current collector are provided at two ends of the case in the axial direction. The current collector is electrically connected to a tab extended from the jelly roll. The current collector includes a protrusion configured to be electrically connected to a pole piece assembly of the cylindrical battery. The protrusion has a chamber communicating with the jelly roll hole. The distance between the surface of the protrusion facing the jelly roll and the end surface of the negative electrode of the jelly roll facing the current collector is "h" in units of mm; the radial dimension of the jelly roll hole is "D" in units of mm; where h / D = 0.2 to 1.8.

[0006] In the cylindrical battery of the present application, a protrusion portion having a chamber is provided on the current collector, and the chamber communicates with the jelly roll hole, so that a venting channel is formed between the current collector and the jelly roll. When the cylindrical battery experiences thermal runaway, the gas accumulated at the first end of the case can be smoothly discharged to the jelly roll hole through the chamber and discharged to the end where the pressure relief structure is positioned through the jelly roll hole. This can prevent the accumulation of gas at the end of the jelly roll opposite the pressure relief structure, thereby preventing the battery deterioration phenomenon caused by the collision of the accumulated gas with the associated structure of the cylindrical battery at the first end.In addition, if the ratio of h / D is limited to the range of 0.2 to 1.8, on the one hand, it can avoid the problem that gas cannot be smoothly discharged from the chamber to the jelly-roll hole, and on the other hand, it can avoid the problem of mutual interference between the tab and the jelly-roll hole caused by the excessive area of ​​the jelly-roll hole, thereby avoiding the problem that the tab blocks the jelly-roll hole and affects the venting. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a structural diagram of a cylindrical battery according to an embodiment of the present application; Fig. 2 is a structural representation of the Fig. 1 shown cylindrical battery from a different viewing angle; Fig. 3 is a cross-sectional view of a cylindrical battery according to an embodiment of the present application; Fig. 4 is an enlarged partial view of part J1 in Fig. 3; Fig. 5 is an enlarged partial view of part J2 in Fig. 4; Fig. 6 is a structural schematic diagram of the tab piece of the jelly roll before bending according to an embodiment of the present application; Fig. 7 is a structural schematic diagram of the tab piece of the jelly roll after bending and stacking according to an embodiment of the present application. In the figures:

[0007] Cylindrical battery 10, first end 101, second end 102; Housing 11, housing body 111, housing peripheral part 1111, housing lower part 1112, cap 112; Jelly roll 12, jelly roll hole 121, end face 122, tab 123, tab piece 1231; pressure relief structure 13; Current collecting piece 14, projection part 141, flat part 1411, peripheral wall part 1412, arcuate transition part 14121, through hole 1413, plate part 142; Pole piece 15, groove part 151, curved wall section 1511; Cavity 1S, gap 2S, space area 3S. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0008] In order to enable those skilled in the art to better understand the scheme of the present application, the present application will be described in more detail below with reference to the accompanying drawings and embodiments.

[0009] With reference to the Fig. 1 to 4, is Fig. 1 is a structural diagram of a cylindrical battery according to an embodiment of the present application, Fig. 2 a structural representation of the Fig. 1 shown cylindrical battery from a different viewing angle, Fig. 3 is a cross-sectional view of a cylindrical battery according to an embodiment of the present application and is Fig. 4 a partially enlarged view of part J1 in Fig. 3. In order to clearly demonstrate the improvement of the present application, Fig. 3 only the case 11, the jelly roll 12, the pressure relief structure 13, the current collecting piece 14 and the pole piece 15 of the cylindrical battery 10, and other structures (such as the connecting and sealing structure between the pole piece 15 and the case 11, etc.) are not shown.

[0010] In the present embodiment, a cylindrical battery 10 is provided which has a case 11 and a jelly roll 12 positioned in the case 11, and the jelly roll 12 has a jelly roll hole 121 formed as a through hole penetrating both end faces of the jelly roll 12.

[0011] The cylindrical battery 10 also includes a pressure relief structure 13 and a current collector 14 electrically connected to the tab 123 extending from the jelly roll 12. The current collector 14 includes a protrusion 141 configured to be electrically connected to a pole piece assembly of the cylindrical battery 10. The protrusion 141 has a chamber 15 communicating with the jelly roll hole 121. The distance between the surface of the protrusion 141 facing the jelly roll 12 and the end surface 122 of the negative electrode of the jelly roll 12 facing the current collector 14 is "h," and the radial dimension of the jelly roll hole 121 is "D," h / D=0.2 to 1.8. In the present embodiment, the distance "h" and the radial dimension "D" are both in mm.

[0012] The cylindrical battery 10 has a first end 101 and a second end 102 that are opposite each other in the axial direction. In the illustrated example, the current collector 14 is provided at the first end 101, and the pressure relief structure 13 is provided at the second end 102.

[0013] In some embodiments, the pressure relief structure 13 may be an annular groove structure provided on the housing bottom part 1112 of the housing body 111. With reference to the Fig. 2 and Fig. 3, the pressure relief structure 13 is an annular groove formed by being recessed from the outer surface of the housing base 1112 toward the first end 101 of the cylindrical battery 10.

[0014] When the cylindrical battery 10 experiences thermal runaway after the internal pressure of the battery reaches a certain value, the pressure relief structure 13 may explode, and the gas accumulated in the battery may be discharged from the position where the pressure relief structure 13 explodes along the jelly roll hole 121 to ensure the safe operating performance of the cylindrical battery 10.

[0015] In the cylindrical battery 10 of the present embodiment, a protrusion portion 141 having a chamber 1S is provided on the current collector 14, and the chamber 1S communicates with the jelly roll hole 121. Thus, a vent passage is formed between the current collector 14 and the jelly roll 12. When the cylindrical battery 10 experiences thermal runaway, the gas accumulated at the first end 101 in the casing 11 can be smoothly discharged through the chamber 1S to the jelly roll hole 121 and discharged through the jelly roll hole 121 to the end where the pressure relief structure 13 is positioned, which can avoid accumulation of gas at the end of the jelly roll 12 remote from the pressure relief structure 13, thereby preventing the phenomenon of a deteriorated battery state caused by the impact of the accumulated gas on the related structures (such as the pole piece 15, etc.).) of the cylindrical battery 10 at the first end 101 is avoided. In addition, the ratio of h / D is limited to the range of 0.2 to 1.8, which can, on the one hand, avoid the problem that the gas cannot be smoothly discharged from the chamber 1S to the jelly-roll hole 121, and, on the other hand, avoid the problem of mutual interference between the tab 123 and the jelly-roll hole 121 caused by the large area of ​​the jelly-roll hole 121, and avoid the problem that the tab 123 blocks the jelly-roll hole 121 and impairs venting.

[0016] In some application examples, the distance “h” between the surface of the projection part 141 facing the jelly roll 12 and the end surface 122 of the negative electrode of the jelly roll 12 facing the current collecting piece 14 is 1.5 mm to 8.6 mm.

[0017] In particular, the above distance “h” may be 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 8.6 mm.

[0018] In some application examples, the radial dimension “D” of the jelly roll hole 121 is 3.5 mm to 8 mm.

[0019] In particular, the radial dimension “D” of the jelly roll hole 121 may be 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm or 8 mm.

[0020] In some application examples, the ratio of h / D can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or 1.8.

[0021] In some embodiments, the housing 11 includes a housing body 111 and a cap 112. The housing body 111 has a generally cylindrical structure. The housing body 111 includes a housing peripheral part 1111 and a housing bottom part 1112. The top of the housing body 111 is open, which is convenient for mounting the jelly roll 12 and related parts (such as an insulating film covering the jelly roll, etc.) of the cylindrical battery 10. The cap 112 is connected to the housing body 111 and serves to cover the top opening of the housing body 111. The housing body 111 and the cap 112 are in a split structure.

[0022] In other embodiments, the housing 11 may also be an integrated structure.

[0023] The cylindrical battery 10 also includes a pole piece 15, and the current collector 14 is electrically connected to the pole piece 15. The current collector 14 is provided to achieve an electrical connection between the pole piece 15 and the tab 123.

[0024] In a specific implementation, the current collector 14 and the tab 123 can be electrically connected by welding, and the current collector 14 and the pole piece 15 can also be electrically connected by welding. Welding is highly reliable and easy to perform.

[0025] In some embodiments, the end surface 122 of the negative electrode of the jelly roll 12 facing the current collector 14 is abbreviated as the end surface 122 of the jelly roll 12, and a space region 3S is formed between the end surface 122 of the jelly roll 12 and the housing 11, and the chamber 1S of the protrusion part 141 communicates with the space region 3S. The space region 3S is positioned between the housing wall of the housing 11 at the end where the current collector 14 and the jelly roll 12 are positioned.In this way, when the cylindrical battery 10 experiences thermal runaway, the gas in the space region 3S can flow smoothly through the chamber 1S and the jelly roll 121 to the side where the pressure relief structure 13 is positioned and be discharged through the explosion part of the pressure relief structure 13, so as to ensure the safety of using the cylindrical battery 10 and reduce the probability of explosion caused by failure of timely gas discharge.

[0026] In the example of the figures, the space area 3S is located between the end face 122 of the jelly roll 12 and the cap 112.

[0027] The end of the projection part 141 of the current collecting piece 14 facing the jelly roll 12 is an open end, and a gap is provided between the end surface of the current collecting piece 14 facing the jelly roll 12 and the jelly roll 12, and the chamber 1S of the projection part 141 can communicate with the space region 3S through the gap.

[0028] In some embodiments, the dimension of the protrusion portion 141 in the axial direction of the cylindrical battery 10 is 1 mm to 6 mm. Such an arrangement can increase the overall venting space and prevent the hot gas from pressing against the side where the protrusion portion 141 is located, causing serious safety accidents.

[0029] Specifically, the dimension of the protrusion portion 141 in the axial direction of the cylindrical battery 10 may be 1 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, or 6 mm.

[0030] In some embodiments, the inner diameter of the chamber 1S of the protrusion portion 141 can be set larger than the opening D of the jelly-roll hole 121. In this way, in the event of thermal runaway, it is convenient to introduce the gas in the space region 3S into the chamber 1S and discharge it through the chamber 1S from the jelly-roll hole 121.

[0031] In some embodiments, the protrusion portion 141 of the current collector 14 includes a flat portion 1411 and a peripheral wall portion 1412 located on the periphery of the flat portion 1411. The flat portion 1411 and the peripheral wall portion 1412 are closed to form the chamber 1S, and the peripheral wall portion 1412 is provided with at least one through-hole 1413. In this way, when the cylindrical battery 10 experiences thermal runaway, the gas accumulated in the space region 3S can flow into the chamber 1S through the through-hole 1413 and be exhausted through the jelly-roll hole 121, which can accelerate the exhaust of the gas accumulated in the space region 3S, reduce the likelihood of the cylindrical battery 10 causing an explosion due to excessive internal gas accumulation, and help ensure the integrity of the state of the cylindrical battery 10 during the thermal runaway.

[0032] In some embodiments, the peripheral wall portion 1412 of the protrusion portion 141 may be provided with a plurality of through-holes 1413, which may be evenly distributed over the circumference of the peripheral wall portion 1412. In this way, the gas in the space region 3S can be more quickly discharged through the chamber 1S into the jelly-roll hole 121, avoiding the explosion caused by excessive gas accumulation in some areas.

[0033] The area of ​​the through-hole 1413 can be arranged appropriately. The area of ​​the through-hole 1413 should not be too large to prevent the gas from impacting the flow collector 14 and affecting the structure of the chamber 1S. The area of ​​the through-hole 1413 should not be too small to prevent a negative impact on the smoothness of the venting.

[0034] During use, the ratio of the sum of the areas of the through holes 1413 provided on the peripheral wall part 1412 to the surface area of ​​the peripheral wall part 1412 is 0.01 to 0.6.

[0035] In particular, the ratio of the sum of the areas of the through holes 1413 to the surface of the peripheral wall part 1412 may be 0.01, 0.02, 0.05, 0.07, 0.1, 0.13, 0.16, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6.

[0036] In actual application, the area of ​​the through holes 1413 can be adjusted in combination with the number and arrangement of the through holes 1413 and the venting requirements of the cylindrical battery 10, which can be determined by simulation or experiment.

[0037] It will be Fig. 5, which is a partially enlarged view of part J2 in Fig. 4 represents.

[0038] In some embodiments, the pole piece 15 has a groove portion 151, and at least a portion of the protrusion portion 141 of the current collector 14 is embedded in the groove portion 151. In this way, the positions of the current collector 14 and the pole piece 15 can be arranged, which facilitates the assembly of the current collector 14 and the pole piece 15.

[0039] As an example, the flat part 1411 of the current collecting piece 14 may be fixed and welded to the bottom wall of the groove part 151 to ensure the electrical connection effect between the current collecting piece 14 and the pole piece 15.

[0040] A gap 2S is provided between the groove side wall of the groove part 151 and the peripheral wall part 1412 of the protruding part 141, and the through-hole 1413 of the peripheral wall part 1412 can communicate with the gap 2S. In this way, the gas in the space area 3S can enter the chamber 1S through the gap 2S and the through-hole 1413 when venting, and then be discharged to the jelly-roll hole 121, thereby avoiding the obstruction of the gas flowing to the chamber 1S through the through-hole 1413 due to the cooperation between the protruding part 141 and the groove part 151, and can ensure that the gas in the space area 3S can be smoothly discharged through the chamber 1S and the jelly-roll hole 121.

[0041] The dimension of the gap 2S can be adjusted according to the actual venting needs, and the specific value is not limited here.

[0042] In a specific implementation, the groove side wall of the groove part 151 includes an arcuate wall portion 1511, and the peripheral wall portion 1412 of the protrusion part 141 is provided with an arcuate transition portion 14121 at an end remote from the flat portion 1411, and the gap 2S is provided between the arcuate wall portion 1511 and the arcuate transition portion 14121. In this way, the air flow channel between the space region 3S and the through-hole 1413 is a channel structure with an arcuate transition between the groove part 151 and the protrusion part 141. When the gas flows from the space region 3S to the gap 2S, there is no large curvature, and the gas can flow more smoothly from the space region 3S to the through-hole 1413.In other words, the coordinated arrangement of the arcuate wall portion 1511 and the arcuate transition part 14121 can reduce the flow resistance of the gas flowing to the through-hole 1413 and facilitate the rapid discharge of the gas in the event of thermal runaway.

[0043] On the Fig. 6 and Fig. 7 jointly, Fig. 6 is a schematic representation of the structure of the jelly roll before the tab piece is bent according to one embodiment, and Fig. 7 is a schematic diagram of the structure of the jelly roll after the tab piece is bent and stacked according to the embodiment.

[0044] The tab 123 of the cylindrical battery 10 extends from the end face of the jelly roll 12. Specifically, the jelly roll 12 includes multiple electrode winding layers, and tab pieces extend from at least a portion of the electrode winding layers. The tab 123 includes multiple layers of the tab piece 1231, which are stacked after the end of the jelly roll 12 is bent.

[0045] During application, the thickness of the single-layer tab piece 1231 is 4 µm to 20 µm, for example, it can be 4 µm, 5 µm, 7 µm, 8 µm, 10 µm, 12 µm, 16 µm, 18 µm, or 20 µm. The thickness of the tab piece 1231 affects the overall thickness of the tab 123 and also affects the distance h between the surface of the protrusion portion 141 facing the jelly roll 12 and the end surface 122 of the jelly roll 12. The thickness of the tab piece 1231 can be appropriately controlled by adjusting the thickness of the tab piece 1231, which is conducive to smooth gas discharge during thermal runaway.

[0046] During application, the maximum thickness “t” (in Fig. 7) of the tab 123, which is formed by bending and stacking the multiple layers of the tab piece 1231, is 0.2 mm to 2 mm. For example, the maximum thickness of the tab 123 can be 0.2 mm, 0.3 mm, 0.4 mm, 0.7 mm, 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, or 2 mm.

[0047] During use, the lead-out length L of the single-layer tab piece 1231 is 2 mm to 12 mm. The lead-out length "L" of the single-layer tab piece 1231 affects the overall thickness of the tab 123 and also affects the connection stability between the tab 123 and the current collector 14, thereby affecting the distance "h" between the surface of the protrusion part 141 facing the jelly roll 12 and the end surface 122 of the jelly roll 12. The lead-out length "L" of the tab piece 1231 can be appropriately controlled by adjusting "h" to facilitate smooth gas discharge during thermal runaway.

[0048] Fig. 6 shows three single-layer tab pieces 1231 with different lead-out lengths.

[0049] In particular, the lead-out length “L” of the single-layer tab piece 1231 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm or 12 mm.

[0050] The jelly roll 12 of the cylindrical battery 10 includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode. At an end of the jelly roll 12 facing the current collector 14, i.e., at the first end 101 of the cylindrical battery 10, the separator of the jelly roll 12 protrudes beyond the negative electrode by 0.5 to 2 mm. In this way, because the separator can provide insulation protection between the positive electrode and the negative electrode, it is possible to prevent the separator from protruding too far beyond the negative electrode and thereby impairing gas emission in the space region 3S.

[0051] In particular, the Jelly-Roll 12 separator protrudes beyond the negative electrode by 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm or 2 mm.

[0052] In some embodiments, a portion of the current collector 14 may be electrically connected to the positive tab extending from the positive electrode of the jelly roll 12, and another portion is electrically connected to the pole piece, with the pole piece serving as the positive output terminal.

[0053] In some embodiments, a portion of the current collector 14 may be electrically connected to the negative tab extending from the negative electrode of the jelly roll 12, and another portion is electrically connected to the pole piece, with the pole piece serving as the negative output terminal.

[0054] The present disclosure illustrates the principles and embodiments of the present application with specific examples. The description of the above embodiments is provided only to aid in understanding the method and gist of the present application. It should be understood that various improvements and modifications to the present application can be made by those skilled in the art without departing from the principles of the present application, and these improvements and modifications are also within the scope of the claims of the present application.

Claims

[1] Cylindrical battery, characterized bythat it comprises a housing and a jelly roll, the jelly roll being positioned within the housing and the jelly roll having a jelly roll hole; the cylindrical battery also comprises a pressure relief structure and a current collector, the pressure relief structure and the current collector are provided at two ends of the housing in the axial direction, the current collector is electrically connected to a tab extending from the jelly roll, the current collector includes a projection portion configured to be electrically connected to a pole piece assembly of the cylindrical battery, the projection portion has a chamber communicating with the jelly roll hole, the distance between the surface of the projection portion facing the jelly roll and the end surface of the negative electrode of the jelly roll facing the current collector is "h" in units of mm;is the radial dimension of the jelly-roll hole “D” in units of mm; where h / D = 0.2 to 1.8; [2] Cylindrical battery according to claim 1, characterized by that the dimension of the protrusion part in the axial direction of the cylindrical battery is 1 mm to 6 mm. [3] Cylindrical battery according to claim 1 or 2, characterized by that the tab comprises several tab layer sections distributed in the radial direction and the maximum thickness of the tab in the axial direction of the cylindrical battery is 0.2 mm to 2 mm. [4] Cylindrical battery according to one of the preceding claims, characterized by that the tab comprises several layers of tab pieces distributed in the radial direction, the jelly roll comprises several electrode winding layers, tab pieces are led out of at least some of the electrode winding layers and the lead-out length of the tab pieces is 2 mm to 12 mm. [5] Cylindrical battery according to one of the preceding claims, characterized by that at one end of the jelly roll facing the current collector, the separator of the jelly roll projects beyond the negative electrode by 0.5 to 2 mm. [6] Cylindrical battery according to one of the preceding claims, characterized by in that the projection part comprises a flat part and a peripheral wall part positioned on the outer periphery of the flat part, the flat part and the peripheral wall part are closed to form the chamber, and the peripheral wall part is provided with at least one through hole. [7] Cylindrical battery according to claim 6, characterized by that the peripheral wall part is provided with several through holes which are evenly distributed over the circumference of the peripheral wall part. [8] Cylindrical battery according to claim 6 or 7, characterized bythat the ratio of the sum of the areas of the through holes to the surface of the peripheral wall part is 0.01 to 0.

6. [9] Cylindrical battery according to one of claims 6 to 8, characterized by that the cylindrical battery comprises a pole piece, the current collecting piece is electrically connected to the pole piece, the pole piece has a groove part, at least a part of the projection part is embedded in the groove part, a gap is provided between the groove side wall of the groove part and the peripheral wall part, and the through hole communicates with the gap. [10] Cylindrical battery according to claim 9, characterized by that the groove side wall comprises an arcuate wall portion provided at an end of the peripheral wall portion remote from the flat portion, and the gap is positioned between the arcuate transition portion and the arcuate wall portion. [11] Cylindrical battery according to one of the preceding claims, characterized by that a space is formed between the end face of the jelly roll facing the current collector and the housing and that the chamber is connected to the space.

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