Connecting piece and encapsulation cooperation structure, battery cell and battery pack

Abstract

The application relates to the technical field of batteries and discloses a connecting sheet and glue-coated cooperation structure, a battery cell and a battery pack. The connecting sheet and glue-coated cooperation structure comprises a connecting sheet which comprises a pole column connecting area, a melting area and a tab connecting area connected in sequence along a first direction, the melting area comprises a melting part and a through hole, the size of the through hole along the first direction is X, the total area of the projection of the melting part on the section perpendicular to the first direction and passing through the center of the through hole is S, wherein a glue-coated layer has a coating part and a filling part, the coating part is coated on the surface of the melting part and extends to outside the melting area along the first direction, the filling part is connected with the coating part and filled in the through hole, and the size of the part of the coating part located on the lower side of the connecting sheet along the up-down direction is c, wherein 0.3mm <= c <= 3mm. The connecting sheet can completely cut off the circuit when melting, the liquid melted from the connecting sheet is prevented from dropping on the pole group to cause thermal runaway, and the safety is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a connecting piece and overlay structure, a battery cell, and a battery pack. Background Technology

[0002] The connecting tab is a crucial structural component in a battery cell, used to connect the tabs of the electrode assembly to the terminals on the cover plate, thus achieving electrical connection between the electrode assembly and the cover plate assembly. To enhance cell safety, the connecting tab is typically equipped with a fuse. In the event of a short circuit in the cell, the fuse melts quickly, causing the connecting tab to disconnect promptly, thus breaking the connection between the electrode assembly and the terminals and preventing further violent reactions within the cell.

[0003] However, when the fuse is triggered, the connecting piece breaks into two halves. If the two halves of the connecting piece are too close together, there is still a phenomenon of arcing between them, causing the electrode group and the terminal to reconnect, thus failing to completely cut off the circuit, which is quite dangerous. Alternatively, when the fuse of the connecting piece melts, the liquid dripping onto the electrode group will continue to trigger thermal runaway, which also increases the danger. Summary of the Invention

[0004] In view of this, the present invention provides a connecting piece and overlay mating structure, a battery cell and a battery pack, to solve the problem that the circuit cannot be completely cut off when the connecting piece melts or that the melted liquid from the connecting piece drips onto the electrode assembly, causing thermal runaway.

[0005] In a first aspect, the present invention provides a connecting piece and an overlay mating structure, comprising: a connecting piece including a pole connecting region, a fusing region, and a tab connecting region sequentially connected along a first direction; the fusing region including a fusing portion and a through hole; the through hole having a dimension X along the first direction; and the total projected area of ​​the fusing portion on a cross-section passing through the center of the through hole and perpendicular to the first direction being S, wherein... The coating layer has a covering portion and a filling portion. The covering portion covers the surface of the fused portion and extends in a first direction beyond the fused area. The filling portion is connected to the covering portion and fills the through hole. The portion of the covering portion located on the lower side of the connecting piece has a dimension c in the vertical direction, wherein 0.3mm≤c≤3mm.

[0006] Beneficial effects: By setting the covering portion of the overlay layer to cover the surface of the fusible portion and extend beyond the fusible area along the first direction, and the filling portion to fill the through hole, the overlay layer can completely enclose the fusible area. Therefore, when the connecting piece melts at the fusible area, the overlay layer can act as an insulating barrier at the break. Furthermore, since the covering portion extends beyond the fusible area along the first direction, the overlay layer can overlap the connecting piece body on both sides of the through hole along the first direction, preventing the filling portion from losing its edge support and falling into the battery cell when the fusible portion melts due to the plastic originally located on the surface of the fusible portion melting from heat. Additionally, by limiting X to 0.5mm... By selecting values ​​within a certain range, it is possible to avoid arcing and short circuits between the two half-piece connecting pieces under high voltage after the fuse melts, ensuring that the circuit is completely cut off when the connecting piece melts. This also ensures the structural strength of the connecting piece during normal operation, thereby improving the reliability of the connecting piece and ensuring the safety of the battery cell. At the same time, by setting the vertical dimension c of the part of the covering portion located on the lower side of the connecting piece to be within the range of 0.3mm to 3mm, the part of the covering portion located on the lower side of the connecting piece is ensured to have a certain thickness. This ensures that this part will not melt when the fuse melts, thereby preventing the molten liquid from dripping onto the electrode assembly and causing thermal runaway, improving safety, saving costs, and improving the internal space utilization of the battery cell.

[0007] In one alternative embodiment, the covering portion covers the surface of the fused portion and extends toward both sides of the fused region along a first direction, wherein the dimension of the covering portion along the first direction is b, where 1.2≤b / X≤5.

[0008] Beneficial effects: It can ensure that the part of the coating that overlaps on the connecting piece body outside the through hole can provide sufficient support for the filling part, preventing the filling part from falling into the cell, thereby ensuring the insulating isolation function of the coating layer, ensuring that the circuit can be completely cut off when the connecting piece melts, improving safety, avoiding material waste, thus saving costs, and also helping to improve the energy density of the cell.

[0009] In one optional embodiment, the total projected area S of the fused portion on a cross-section passing through the center of the through hole and perpendicular to the first direction ranges from 4mm. 2 ≤S≤12mm 2 .

[0010] Beneficial effects: It can ensure that the connecting piece has sufficient strength and the stability of the connecting piece structure, and it can also ensure that the fuse can melt in time when the battery cell is short-circuited, thus ensuring the safety of the battery cell.

[0011] In one optional embodiment, the dimension of the fused portion in the vertical direction is t, and the dimension of the portion of the covering portion located on the upper side of the connecting piece in the vertical direction is a, wherein 0.5≤a / t≤5.

[0012] Beneficial effects: It can ensure that when the fuse breaks, the molten plastic on the upper side of the connecting piece can fill the barrier area formed after the fuse breaks, thus playing an insulating role and avoiding continuous short circuits caused by high voltage arcing, thereby ensuring the safety of the battery cell. It can also save costs and improve the internal space utilization of the battery cell.

[0013] In one optional embodiment, the dimension t of the fuse portion in the vertical direction ranges from 0.6mm to t to 2mm.

[0014] Beneficial effects: It can ensure that the connecting piece has sufficient structural strength and improve the reliability of the connecting piece, while also controlling production costs and increasing the volumetric energy density of the battery cell.

[0015] In one optional embodiment, the covering portion protrudes from the fusion break area along a second direction, and the value of the distance d that the covering portion exceeds the fusion break area in the second direction is in the range of 0.3mm≤d≤3mm, wherein the second direction is perpendicular to the first direction in the plane containing the upper surface of the connecting piece.

[0016] Beneficial effects: It can ensure that when the fuse breaks, the molten plastic on the upper side of the connecting piece can fill the barrier area formed after the fuse breaks, thus playing an insulating role and preventing continuous short circuits caused by high voltage arcing, thereby ensuring the safety of the battery cell. It can also control costs and avoid wasting materials.

[0017] In one alternative embodiment, along the second direction, the minimum distance from the edge of the through hole to the side of the connecting piece is e, where 1.5mm≤e≤20mm.

[0018] Beneficial effects: It can ensure that the connecting piece has sufficient structural strength, avoid bending and deformation of the connecting piece under mechanical impact, improve the reliability of the connecting piece, and ensure that the fuse can melt in time when the battery cell is short-circuited, thereby improving the safety of the battery cell.

[0019] In one optional embodiment, the two sides of the through hole along the second direction are constructed with rounded corners, and the radius of the circle containing the rounded corners is R, where R = X / 2.

[0020] Beneficial effects: By constructing rounded corners on both sides of the through hole along the second direction, and the radius R of the circle containing the rounded corners is half the dimension X of the through hole along the first direction, the through hole is oval, the outer contour of the through hole is smoothly transitioned, the structure has good strength and is easy to process, the connecting piece is not easy to break under mechanical impact, the reliability is high, and the safety is good.

[0021] Secondly, the present invention also provides a battery cell, comprising: a housing having an open end; an electrode assembly disposed within the housing, the electrode assembly having tabs; a cover plate disposed at the open end of the housing to close the housing, the cover plate having a terminal post; and the aforementioned connecting piece and rubber-coated mating structure, wherein the terminal post connecting area of ​​the connecting piece is connected to the terminal post and the tab connecting area is connected to the tab.

[0022] Since the battery cell includes a connecting piece and an encapsulation structure, it has the same effect as the connecting piece and encapsulation structure, so it will not be elaborated here.

[0023] Thirdly, the present invention also provides a battery pack, comprising: the aforementioned battery cell. Since the battery pack includes the battery cell and has the same effects as the battery cell, it will not be described further here. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a top view of a connecting piece and adhesive coating structure according to an embodiment of the present invention;

[0026] Figure 2 for Figure 1 A cross-sectional view along the MM direction of the connecting piece and the rubber-coated mating structure shown;

[0027] Figure 3 for Figure 2 A magnified view of part of F;

[0028] Figure 4 This is a top view of a connecting piece according to an embodiment of the present invention;

[0029] Figure 5 for Figure 4 A cross-sectional view of the connecting piece along the NN direction;

[0030] Figure 6 for Figure 4 The front view of the connecting piece is shown;

[0031] Figure 7 This is a top view of another connecting piece according to an embodiment of the present invention;

[0032] Figure 8 This is a cross-sectional view of the connecting piece and the overlay structure according to an embodiment of the present invention after the fusion section is broken and the upper side of the overlay is melted and deformed.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Connecting piece; 110. Pole post connection area; 120. Fusible area; 121. Fusible part; 122. Through hole; 130. Pole tab connection area; 2. Coating layer; 210. Covering part; 220. Filler part. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The following is combined with Figures 1 to 8 The following describes embodiments of the present invention.

[0037] According to an embodiment of the present invention, in one aspect, a connecting piece and an adhesive-coated mating structure is provided, comprising: a connecting piece 1 and an adhesive-coated layer 2. The connecting piece 1 includes a pole post connecting region 110, a fusing region 120, and a tab connecting region 130 sequentially connected along a first direction. The fusing region 120 includes a fusing portion 121 and a through hole 122. The through hole 122 has a dimension X along the first direction. The total projected area of ​​the fusing portion 121 on a cross-section passing through the center of the through hole 122 and perpendicular to the first direction is S. The overlay layer 2 has a covering portion 210 and a filling portion 220. The covering portion 210 covers the surface of the fusion-breaking portion 121 and extends beyond the fusion-breaking area 120 along a first direction. The filling portion 220 is connected to the covering portion 210 and fills the through hole 122. The portion of the covering portion 210 located below the connecting piece 1 has a vertical dimension c, where 0.3mm ≤ c ≤ 3mm. The first direction refers to... Figures 1 to 4 and Figure 7 The middle arrow points to the "first direction"; the up and down directions refer to... Figures 2 to 3 The direction indicated by the middle arrow is "up and down".

[0038] By employing the connecting piece and overlay structure of this embodiment, the overlay layer 2 has a covering portion 210 that covers the surface of the fusible portion 121 and extends beyond the fusible area 120 along the first direction, and a filling portion 220 that fills the through hole 122. This means the overlay layer 2 can completely enclose the fusible area 120. Therefore, when the connecting piece 1 melts at the fusible area 120, the overlay layer 2 can provide insulation at the break. Furthermore, since the covering portion 210 extends beyond the fusible area 120 along the first direction, the overlay layer 2 can overlap the connecting piece body on both sides of the through hole 122 along the first direction. This prevents the filling portion 220 from losing its edge support and falling into the battery cell when the fusible portion 121 melts due to the plastic on its surface melting from heat. Additionally, by limiting X to 0.5 mm... By taking values ​​within a certain range, it is possible to avoid arcing and short circuits between the two half-piece connecting pieces under high voltage after the fuse 121 melts, ensuring that the circuit can be completely cut off when the connecting piece 1 melts. It is also possible to ensure the structural strength of the connecting piece 1 during normal operation, thereby improving the reliability of the connecting piece 1 and ensuring the safety of the battery cell. At the same time, by setting the dimension c of the part of the covering part 210 located on the lower side of the connecting piece 1 in the vertical direction to be within the range of 0.3mm to 3mm, it is possible to ensure that the part of the covering part 210 located on the lower side of the connecting piece 1 has a certain thickness. This ensures that this part will not melt when the fuse 121 melts, thereby preventing the molten liquid of the connecting piece 1 from dripping onto the electrode group and causing thermal runaway, improving safety, saving costs, and also improving the internal space utilization of the battery cell.

[0039] It should be noted that the connecting piece 1 is made of metal. The fusible portion 121 and the through hole 122 in the fusing area 120 are arranged along the second direction, which is the direction perpendicular to the first direction within the plane containing the upper surface of the connecting piece 1. Because the fusing area 120 has the through hole 122, the solid portion of the fusing area 120 is reduced (i.e., the fusing portion 121 is formed), the cross-sectional area decreases, and the resistance increases. Therefore, when current flows, the heat generated on the fusing portion 121 is relatively large. Thus, when the battery short-circuits and generates a large instantaneous current, the fusing portion 121 melts due to excessive heat, causing the connecting piece 1 to break from the fusing area 120, thereby cutting off the circuit and protecting the battery. The upper surface refers to... Figure 2 The surface in the direction indicated by the middle arrow, which points to "up".

[0040] It should be noted that the cross-section perpendicular to the center of the through hole 122 in the first direction refers to... Figure 4 In the NN section, on this section, the total cross-sectional area of ​​the fuse portion 121 is ( Figure 5The shaded area represents the total projected area S of the fuse portion 121 on the cross-section perpendicular to the first direction at the center of the through hole 122. The dimension X of the through hole 122 along the first direction is equal to the dimension X of the fuse portion 121 along the first direction. When the battery short-circuits and the fuse portion 121 of the connecting piece 1 melts, the distance between the two broken connecting pieces is X. If X is less than 0.5mm, then X is too small, and after the fuse portion 121 melts, an arcing short circuit will still occur between the two connecting pieces under high voltage, which is quite dangerous. If X is greater than half the value of S, then X is too large, and the structural strength of the connecting piece 1 is poor, making it easy to break under mechanical impact, which will also affect the safety of the battery cell.

[0041] Furthermore, the overlay layer 2 is made of plastic. The portion of the overlay 210 located below the connecting piece 1 can catch the molten metal when the fusion section 121 melts, preventing the molten metal from dripping onto the electrode assembly and further aggravating thermal runaway. Therefore, it is necessary to ensure that the portion of the overlay 210 located below the connecting piece 1 has a certain thickness so that it will not melt when heated. If the vertical dimension c of the portion of the overlay 210 located below the connecting piece 1 is less than 0.3 mm, then the thickness of the portion of the overlay 210 located below the connecting piece 1 is... If the thickness is too small, the heat generated on the fuse 121 during a short circuit will melt the portion of the covering 210 located below the connecting piece 1, causing the molten metal and plastic to drip onto the electrode assembly, further exacerbating thermal runaway. If the vertical dimension c of the portion of the covering 210 located below the connecting piece 1 is greater than 3mm, the thickness of this portion will be too large, resulting in excessive weight, higher cost, and occupying too much space in the vertical direction, which is detrimental to improving the utilization rate of the internal space of the battery cell. It should be noted that the high temperature generated on the fuse 121 during a short circuit is instantaneous. After the fuse 121 melts, no further high temperature is generated. It is sufficient to ensure that the portion of the covering 210 located below the connecting piece 1 does not melt during the instantaneous high temperature.

[0042] The connector and overlay structure of this embodiment simultaneously limits the range of the dimension X of the through hole 122 along the first direction and the dimension c of the portion of the covering part 210 located on the lower side of the connector 1 along the vertical direction. This solves both the problem that the circuit cannot be completely cut off when the connector melts and the problem that the melted liquid of the connector drips onto the electrode assembly and causes thermal runaway.

[0043] In one embodiment, the covering portion 210 covers the surface of the fusible portion 121 and extends towards both sides of the fusible region 120 along a first direction. The dimension of the covering portion 210 along the first direction is b, where 1.2 ≤ b / X ≤ 5. Specifically, along the first direction, the covering portion 210 partially overlaps the connecting piece body on both sides of the through hole 122 on the connecting piece 1. This improves the stability of the overlapping of the covering portion 210 on the connecting piece 1 after the fusible portion 121 melts, thereby further preventing the filling portion 220 from falling into the cell. Here, b and X are both in mm.

[0044] The dimension b of the covering portion 210 along the first direction is greater than the dimension X of the through hole 122 along the first direction. The larger the ratio of the dimension b of the covering portion 210 along the first direction to the dimension X of the through hole 122 along the first direction, the more of the covering portion 210 overlaps with the portion outside the through hole 122, and the better the support effect of the adhesive layer 2 on the filling portion 220. If b / X is less than 1.2, the portion of the covering portion 210 overlapping with the connecting piece body outside the through hole 122 is too small, resulting in insufficient support effect on the filling portion 220. When the encapsulation corresponding to the fuse part 121 melts due to heat, there is still a risk that the filler part 220 will fall into the cell. This would cause the encapsulation layer 2 to fail to provide insulation at the through hole 122, making it prone to high-voltage arcing at the through hole 122. In other words, the circuit cannot be completely cut off, resulting in a continuous short circuit. If b / X is greater than 5, the portion of the encapsulation part 210 that overlaps with the connecting piece body outside the through hole 122 will be too large, wasting materials, increasing costs, and increasing weight, which is not conducive to improving the energy density of the cell. Therefore, by limiting the ratio between the dimension b of the covering portion 210 along the first direction and the dimension X of the through hole 122 along the first direction to satisfy 1.2≤b / X≤5, it can be ensured that the portion of the covering portion 210 overlapping the connecting piece body outside the through hole 122 can provide sufficient support for the filling portion 220, preventing the filling portion 220 from falling into the battery cell, thereby ensuring the insulating and insulating function of the coating layer 2, ensuring that the circuit can be completely cut off when the connecting piece 1 melts, improving safety, avoiding material waste, thus saving costs, and also helping to improve the energy density of the battery cell.

[0045] Preferably, the two portions of the covering portion 210 extending along the first direction to both sides of the fusion zone 120 have equal dimensions in the first direction, which further improves the stability of the overlap of the covering portion 210 on the connecting piece body outside the through hole 122.

[0046] In one embodiment, the dimension X of the through hole 122 along the first direction ranges from 0.5mm to 6mm. It should be noted that if X is greater than 6mm, the structural strength of the connecting piece 1 is too large, making it prone to breakage under mechanical impact, which also affects the safety of the battery cell. Therefore, by setting X within the range of 0.5mm to 6mm, it is possible to avoid arcing and short circuits between the two half-piece connecting pieces under high voltage after the fuse 121 melts, while also ensuring the structural strength of the connecting piece 1 during normal operation, thereby improving the reliability of the connecting piece 1 and ensuring the safety of the battery cell.

[0047] In one embodiment, the total projected area S of the fuse portion 121 on the cross-section perpendicular to the first direction at the center of the through hole 122 is within the range of 4mm. 2 ≤S≤12mm 2 It should be noted that the larger the total projected area S of the fused portion 121 on the cross-section perpendicular to the first direction at the center of the through hole 122, the less likely it is to fuse. If S is greater than 12mm... 2 If S is too large, the fuse part 121 will be difficult to melt when the cell is short-circuited, and the fuse area 120 will not play a short-circuit protection role. A large current will continue to flow through the cell, which can easily lead to dangerous situations such as combustion and explosion. If S is less than 4mm... 2 If the cross-sectional area of ​​the fuse portion 121 is too small, the structural strength of the fuse zone 120 will be insufficient, and the stability of the connecting piece 1 will be poor. Therefore, by setting the total projected area S of the fuse portion 121 on the cross-section at the center of the through hole 122 and perpendicular to the first direction to be within 4 mm², 2 Up to 12mm 2 The range of values ​​ensures that the connecting piece 1 has sufficient strength and the stability of the connecting piece 1 structure, and also ensures that the fuse part 121 can melt in time when the battery cell is short-circuited, thus ensuring the safety of the battery cell.

[0048] Specifically, for battery cells with a capacity of less than 90Ah, the total cross-sectional area S of the fuse section 121 is currently 4mm². 2 Correspondingly, the dimension X of the through hole 122 along the first direction is ≤ 2mm; for a battery cell with a capacity of 90Ah-130Ah, the total cross-sectional area S of the fuse part 121 is 6mm². 2 Correspondingly, the dimension X of the through hole 122 along the first direction is ≤3mm; for a battery cell with a capacity of 130Ah-160Ah, the total cross-sectional area S of the fuse part 121 is 8mm². 2 Correspondingly, the dimension X of the through hole 122 along the first direction is ≤ 4 mm, or the total cross-sectional area S of the fuse portion 121 is 10 mm². 2 Correspondingly, the dimension X of the through hole 122 along the first direction is ≤ 5mm; for cells with a capacity higher than 160Ah, the total cross-sectional area S of the fuse part 121 is 12mm².2 Correspondingly, the dimension X of the through hole 122 along the first direction is ≤6mm.

[0049] In one embodiment, the dimension of the fuse portion 121 in the vertical direction is t, and the dimension of the portion of the covering portion 210 located on the upper side of the connecting piece 1 in the vertical direction is a, where 0.5 ≤ a / t ≤ 5. Here, the vertical direction refers to... Figure 2 , Figure 3 and Figure 5 The vertical dimension of the fuse section 121, as indicated by the middle arrow, is its thickness. Similarly, the vertical dimension of the portion of the covering portion 210 located above the connecting piece 1 is its thickness. "Above" refers to... Figures 2 to 3 The side indicated by the middle arrow, specifically, when the connecting piece 1 is installed in the battery cell, the upper side of the connecting piece 1 faces the cover plate, and the lower side of the connecting piece 1 faces the electrode group; when the battery cell is short-circuited, the fuse 121 generates instantaneous high temperature. Simultaneously with the fuse 121 melting, the plastic portion of the overlay layer 2 close to the fuse 121 melts due to heat. Under the influence of gravity, the melted plastic collapses downwards, filling the barrier area formed after the fuse 121 melts, thus providing insulation. Figure 8 The diagram shows a cross-sectional view of the connecting piece and the encapsulated structure after the fused section 121 is fused. This cross-section is parallel to the MM section and passes through the fused section 121. After the encapsulated part 210 melts, it fills the barrier area between the two half connecting pieces, thereby forming a structure in which the upper surface of the encapsulated part 210 is recessed downward.

[0050] It should be noted that if a / t is less than 0.5, the thickness of the portion of the covering part 210 located on the upper side of the connecting piece 1 is too small relative to the thickness of the connecting piece 1. The molten plastic cannot fill the barrier area formed after the fused part 121 is fused, and the barrier area cannot be formed. The insulation effect is poor, and there is still a high voltage arcing phenomenon between the two half-piece connecting pieces. The battery cell is continuously short-circuited, which is very dangerous. If a / t is greater than 5, the thickness of the portion of the covering part 210 located on the upper side of the connecting piece 1 is too large relative to the thickness of the connecting piece 1. The weight is too large, the cost is high, and it will occupy too much space in the vertical direction, which is not conducive to improving the utilization rate of the internal space of the battery cell. Therefore, by setting the vertical dimension 'a' of the portion of the covering part 210 located on the upper side of the connecting piece 1 and the vertical dimension 't' of the fusing part 121 to satisfy the relationship 0.5 ≤ a / t ≤ 5, it can be ensured that when the fusing part 121 melts, the molten plastic of the covering part 210 located on the upper side of the connecting piece 1 can fill the barrier area formed after the fusing part 121 melts, playing an insulating role and avoiding continuous short circuits caused by high-voltage arcing, thereby ensuring the safety of the battery cell. This also saves costs and improves the internal space utilization of the battery cell. Here, both 'a' and 't' are in mm.

[0051] In one embodiment, the vertical dimension t of the fuse portion 121 is in the range of 0.6mm ≤ t ≤ 2mm. If the vertical dimension t of the fuse portion 121 is less than 0.6mm, the thickness of the fuse portion 121 is too small, resulting in poor structural strength. The connecting piece 1 is prone to bending and deformation under mechanical impact, leading to poor reliability. If t is greater than 2mm, the thickness of the fuse portion 121 is too large, increasing the cost of the connecting piece 1 and hindering the improvement of the volumetric energy density of the battery cell. Therefore, by setting the vertical dimension t of the fuse portion 121 to be within the range of 0.6mm to 2mm, it is possible to ensure that the connecting piece 1 has sufficient structural strength, improve the reliability of the connecting piece 1, control production costs, and improve the volumetric energy density of the battery cell.

[0052] In one embodiment, the covering portion 210 protrudes beyond the fusion fracture area 120 along the second direction. The value of the distance d that the covering portion 210 exceeds the fusion fracture area 120 in the second direction is in the range of 0.3mm ≤ d ≤ 3mm, where the second direction refers to... Figure 1 The "second direction" indicated by the middle arrow is perpendicular to the first direction in the plane containing the upper surface of the connecting piece 1. It should be noted that when the fusible part 121 melts, the covering part 210 melts and fills the barrier area formed after the fusible part 121 melts. If d is less than 0.3 mm, the portion of the covering part 210 that exceeds the fusible part 120 is too small to fill the barrier area formed after the fusible part 121 melts, and an effective barrier area cannot be formed, resulting in poor insulation. If d is greater than 3 mm, the portion of the covering part 210 that exceeds the fusible part 120 is too large, resulting in excessive material usage for the adhesive layer 2, wasting material, and increasing costs. Therefore, by providing a covering portion 210 that protrudes from the fusible area 120 in the second direction, the covering portion 210 also protects the sides of the fusible area 120 on both sides in the second direction. Furthermore, by providing a distance d between the covering portion 210 and the fusible area 120 in the second direction that is greater than the fusible area 120, which is within the range of 0.3mm to 3mm, it can be ensured that when the fusible area 121 melts, the molten plastic of the covering portion 210 located on the upper side of the connecting piece 1 can fill the barrier area formed after the fusible area 121 melts, thus playing an insulating and barrier role, avoiding continuous short circuits caused by high-voltage arcing, thereby ensuring the safety of the battery cell, and also controlling costs and avoiding material waste.

[0053] In one embodiment, the minimum distance from the edge of the through hole 122 to the side of the connecting piece 1 along the second direction is e, where 1.5mm ≤ e ≤ 20mm. It should be noted that the minimum distance e from the edge of the through hole 122 to the side of the connecting piece 1 along the second direction is the minimum dimension of the fuse portion 121 along the second direction. If e is less than 1.5mm, the distance from the through hole 122 to the side of the connecting piece 1 is too small, the dimension of the fuse portion 121 along the second direction is too small, the structural strength is poor, and the connecting piece 1 is easily bent and deformed under mechanical impact. If e is greater than 20mm, the distance from the through hole 122 to the side of the connecting piece 1 is large. Given a fixed outer contour dimension of the connecting piece 1, the dimension occupied by the fuse portion 121 along the second direction is too large, and the dimension of the through hole 122 along the second direction is too small. The fuse portion 121 is difficult to fuse, and the connecting piece 1 cannot effectively provide fuse protection when the battery cell is short-circuited. Therefore, by setting the minimum distance e from the edge of the through hole 122 to the side of the connecting piece 1 to be within the range of 1.5mm to 20mm, it is possible to ensure that the connecting piece 1 has sufficient structural strength, avoid bending and deformation of the connecting piece 1 under mechanical impact, improve the reliability of the connecting piece 1, and ensure that the fuse part 121 can melt in time when the battery cell is short-circuited, thereby improving the safety of the battery cell.

[0054] In one embodiment, further combination Figure 4 As shown, the two sides of the through hole 122 along the second direction are rounded, and the radius of the circle containing the rounded corner is R, where R = X / 2. By making the two sides of the through hole 122 along the second direction rounded, and the radius R of the circle containing the rounded corner is half of the dimension X of the through hole 122 along the first direction, the through hole 122 is oblong, the outer contour of the through hole 122 is smoothly transitioned, the structure has good strength and is easy to process, the connecting piece 1 is not easy to break under mechanical impact, the reliability is high, and the safety is good.

[0055] Further integration Figure 4 As shown, the minimum distance e from the edge of the through hole 122 to the side of the connecting piece 1 refers to the distance from the outline of the through hole 122 to the side of the adjacent connecting piece on a straight line along the second direction and passing through the center of the circle containing the fillet. Specifically, the through hole 122 is located in the middle of the fusing area 120 along the second direction, and the distances from both sides of the through hole 122 along the second direction to the sides of their respective adjacent connecting pieces 1 are equal. The total projected area S of the fusing portion 121 on the cross section passing through the center of the through hole 122 and perpendicular to the first direction is equal to twice the product of the minimum distance e from the edge of the through hole 122 to the side of the connecting piece 1 and the dimension t of the fusing portion 121 along the vertical direction, i.e., S = 2et.

[0056] In addition, in other embodiments, further combined Figure 7As shown, the through hole 122 can also be set as a square hole. The long side of the square hole is parallel to the second direction and the short side is parallel to the first direction. The distance from each position on the short side of the square hole to the side of the adjacent connecting piece is equal, and this distance is e.

[0057] Fuse fusing tests and mechanical vibration tests were conducted on connecting pieces with different parameter values ​​for the connecting piece and the rubber-coated mating structure. The test results are described below to verify that the connecting piece and rubber-coated mating structure of this embodiment can better play a role in thermal runaway protection.

[0058] The fuse breaking test specifically involves connecting an external power supply and applying the corresponding current to perform a fuse breaking test, observing the breaking condition and effective circuit breaking status of the fuse part 121 on the connecting piece 1. The mechanical vibration test includes mechanical impact and battery pack vibration. The mechanical impact test specifically uses a 7g, 6ms half-sine wave waveform, with the axial direction being Z; the number of impacts is 6 in each of the positive and negative directions; the interval between two adjacent impacts is not less than 5 times the duration of the impact pulse. Battery pack vibration is tested using a sine wave frequency sweep, 7-18Hz: 10m / s². 2 18-30Hz: from 10m / s 2 Gradually decrease to 2m / s 2 30-50Hz: 2m / s 2 Each scan takes 15 minutes, for a total of 12 scans, over a period of 3 hours.

[0059] Table 1. Test results of implementation cases for connecting pieces with different parameters.

[0060]

[0061] Table 2 Comparison of test results for connecting pieces with different parameters

[0062]

[0063] As can be seen from Table 1, for the connecting piece and overmolding structure in Implementation Case 1, all parameters are close to the lower limit; in Implementation Case 2, S = 4mm 2 X = 1.9 mm, X ratio Slightly smaller; in implementation case 3, S = 6mm 2 X = 3mm, X equals In implementation case 4, S = 8mm 2 X = 3.8 mm, X ratio Slightly smaller; in implementation case 5, S = 10 mm 2 X = 5mm, X equals In implementation case 6, S = 12 mm 2 X = 5.9 mm, X is more than Slightly smaller; that is, for the connecting piece and overmolding fit structure of embodiments 2 to 6, the value of X is closer to the upper limit, while other parameters are closer to the lower limit; for the connecting piece and overmolding fit structure of embodiment 7, all parameters are conventional. For the connecting piece and overmolding fit structure of embodiments 1 to 7, all parameters are within the range defined in this application, and the dimension X of the through hole 122 along the first direction is defined in this application as 0.5 mm to... Within the range, the portion of the covering part 210 located below the connecting piece 1 has a vertical dimension c within the range of 0.3 mm to 3 mm as defined in this application. The connecting piece did not fail after undergoing the Fuse melting test and mechanical vibration test, and the test was passed.

[0064] However, as shown in Table 2, for the connecting piece and rubber-coated structure in Comparative Case 1, X = 0.48 mm, which is less than 0.5 mm. This means that the value of X exceeds the lower limit specified in this application and is outside the scope defined by this application. All other parameters are within the scope defined by this application. After the fuse melts, the through-hole 122 is filled with a rubber layer, but an arcing short circuit still occurs under high pressure. For the connecting piece and rubber-coated structures in Comparative Cases 2 to 6, the value of X is greater than... X exceeded the upper limit, and the fuse cracked after vibration test; for the connecting piece and the encapsulation structure of Comparative Case 7, the dimension c of the part of the encapsulation 210 located on the lower side of the connecting piece 1 in the vertical direction is 0.27mm, which is less than 0.3mm. That is, the value of c exceeds the lower limit value defined in this application and is not within the range defined in this application. Other parameters are okay. When the fuse melts, molten metal drips into the cell.

[0065] In summary, when the dimension X of the through hole 122 along the first direction is defined in this application as 0.5 mm to... Within the specified range, when the vertical dimension c of the portion of the covering part 210 located below the connecting piece 1 is within the range of 0.3mm to 3mm as defined in this application, it can both prevent arcing and short circuit between the two half-piece connecting pieces under high voltage after the fuse part 121 melts, ensuring that the circuit can be completely cut off when the connecting piece 1 melts, and at the same time ensure that the portion of the covering part 210 located below the connecting piece 1 has a certain thickness, ensuring that this portion will not melt when the fuse part 121 melts, thereby preventing the molten liquid of the connecting piece 1 from dripping onto the electrode assembly and causing thermal runaway, thus improving safety.

[0066] Furthermore, regarding the connector and overlay mating structure in Comparative Case 8, b / X equals 1.18, which is less than 1.2, exceeding the lower limit specified in this application and outside the scope defined in this application. Other parameters are okay. When the fuse melts, the overlay at the through hole falls off, and the connector experiences high-voltage arcing and a continuous short circuit. It is evident that when the dimension b of the covering portion 210 along the first direction and the dimension X of the through hole 122 along the first direction satisfy the ratio 1.2 ≤ b / X ≤ 5, it can be ensured that the portion of the covering portion 210 overlapping the connector body outside the through hole 122 can provide sufficient support for the filling portion 220, preventing the filling portion 220 from falling into the cell, thereby ensuring the insulating and isolating function of the overlay layer 2, ensuring that the circuit can be completely cut off when the connector 1 melts, and improving safety.

[0067] For the connecting piece and the encapsulated structure in Comparative Case 9, a / t is 0.47, which is less than 0.5 and exceeds the lower limit specified in this application. It is not within the range specified in this application. Other parameters are okay. The melted plastic did not fill the barrier area, and the connecting piece experienced a continuous short circuit due to high-voltage arcing. It can be seen that when the vertical dimension a of the encapsulated portion 210 located on the upper side of the connecting piece 1 and the vertical dimension t of the fused portion 121 satisfy the relationship 0.5≤a / t≤5, it can be ensured that when the fused portion 121 melts, the melted plastic of the encapsulated portion 210 located on the upper side of the connecting piece 1 can fill the barrier area formed after the fused portion 121 melts, thus providing insulation and preventing a continuous short circuit caused by high-voltage arcing.

[0068] For the connecting piece and the encapsulated structure in Comparative Case 10, the distance d that the encapsulated portion 210 extends beyond the fused portion 121 in the second direction is 0.29 mm, which is less than 0.3 mm. This exceeds the lower limit value defined in this application and is not within the range defined in this application. Other parameters are okay. The side plastic melts but does not fill the barrier area, resulting in a continuous short circuit due to high-voltage arcing. It can be seen that when the distance d that the encapsulated portion 210 extends beyond the fused portion 121 in the second direction is within the range of 0.3 mm to 3 mm, it can be ensured that when the fused portion 121 melts, the melted plastic of the encapsulated portion 210 located on the upper side of the connecting piece 1 can fill the barrier area formed after the fused portion 121 melts, thus playing an insulating barrier role and avoiding a continuous short circuit caused by high-voltage arcing.

[0069] For the connecting piece and rubber-coated structure in Comparative Case 11, R1 is not rounded, X is standard, and other parameters are below the lower limit. After vibration testing, the fuse cracked. It can be seen that when the two sides of the through hole 122 along the second direction are rounded, the outer contour of the through hole 122 transitions smoothly, the structural strength is better and it is easier to process, and the connecting piece 1 is not easy to break under mechanical impact.

[0070] According to an embodiment of the present invention, another aspect provides a battery cell, comprising: a housing, an electrode assembly, a cover plate, and the aforementioned connecting piece and encapsulation mating structure. The housing has an open end; the electrode assembly is disposed within the housing and has tabs; the cover plate is disposed at the open end of the housing to close the housing, and a terminal post is disposed on the cover plate; the terminal post connecting area 110 of the connecting piece 1 is connected to the terminal post, and the tab connecting area 130 is connected to the tab.

[0071] In one embodiment, further combination Figure 6 As shown, the connecting piece 1 has a boss-type structure, that is, the upper surface of the pole connection area 110 is higher than the upper surface of the tab connection area 130, and the lower surface of the pole connection area 110 is higher than the lower surface of the tab connection area 130, so as to make full use of the internal space of the cell. The fuse area 120 is flush with the tab connection area 130.

[0072] In this embodiment, the connecting piece 1 in the battery cell can quickly melt and break when the battery cell is short-circuited without causing the risk of reconnection; it can also prevent the melted liquid of the connecting piece 1 and the adhesive layer 2 from dripping onto the electrode assembly, ensuring the safe use of the battery cell.

[0073] According to an embodiment of the present invention, in another aspect, a battery pack is also provided, comprising: the above-described battery cells. Preferably, the number of battery cells is multiple.

[0074] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A connecting piece and an adhesive-coated structure, characterized in that, include: The connecting piece includes a pole connection area, a fusible connection area, and a tab connection area connected sequentially along a first direction. The fusible connection area includes a fusible portion and a through hole. The through hole has a dimension X along the first direction. The total projected area of ​​the fusible portion on a cross-section passing through the center of the through hole and perpendicular to the first direction is S. ; The coating layer has a covering portion and a filling portion. The covering portion covers the surface of the fused portion and extends in a first direction beyond the fused area. The filling portion is connected to the covering portion and fills the through hole. The portion of the covering portion located on the lower side of the connecting piece has a dimension c in the vertical direction, wherein 0.3 mm ≤ c ≤ 3 mm. The covering portion covers the surface of the fused portion and extends toward both sides of the fused region along a first direction. The dimension of the covering portion along the first direction is b, where 1.2≤b / X≤5. The dimension of the fused portion along the vertical direction is t, and the dimension of the portion of the covering portion located on the upper side of the connecting piece along the vertical direction is a, wherein 0.5≤a / t≤5; After the covering part melts, it fills the barrier area between the two half-piece connecting pieces, forming a structure in which the upper surface of the covering part is concave downwards. The covering portion protrudes from the fusion break area along the second direction. The value of the distance d that the covering portion exceeds the fusion break area in the second direction is 0.3 mm ≤ d ≤ 3 mm. The second direction is perpendicular to the first direction in the plane containing the upper surface of the connecting piece.

2. The connecting piece and the adhesive-coated mating structure according to claim 1, characterized in that, The total projected area S of the fused portion on the cross-section passing through the center of the through hole and perpendicular to the first direction ranges from 4 mm. 2 ≤S≤12mm 2 .

3. The connecting piece and the adhesive-coated mating structure according to claim 1, characterized in that, The value range of the dimension t of the fuse part in the vertical direction is: 0.6 mm ≤ t ≤ 2 mm.

4. The connecting piece and the adhesive-coated mating structure according to claim 1, characterized in that, Along the second direction, the minimum distance from the edge of the through hole to the side of the connecting piece is e, where 1.5 mm ≤ e ≤ 20 mm.

5. The connecting piece and the adhesive-coated mating structure according to claim 1, characterized in that, The two sides of the through hole along the second direction are rounded, and the radius of the circle containing the rounded corner is R, where R = X / 2.

6. A battery cell, characterized in that, include: The shell has an open end; An electrode assembly is disposed within the housing, and the electrode assembly has electrode tabs; A cover plate is provided at the open end of the housing to close the housing, and an pole post is provided on the cover plate; The connecting piece and the overmolded structure according to any one of claims 1 to 5, wherein the pole post connecting area of ​​the connecting piece is connected to the pole post and the tab connecting area is connected to the tab.

7. A battery pack, characterized in that, include: The battery cell according to claim 6.

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