Battery pack

Abstract

The battery pack comprises a plurality of batteries, each battery comprises a shell, a cover plate, a pole, a conducting bar and a battery cell, and the shell is provided with an opening; the cover plate covers the opening, and a through hole is formed in the cover plate; the pole is arranged in the through hole; the conducting bar is electrically connected with one surface, deviating from the battery cell, of the pole; the battery cell comprises a battery cell main body and a tab, the battery cell main body is arranged in the shell, the tab comprises a first connecting part, a fusing part and a second connecting part, the sectional area of the first connecting part and the sectional area of the second connecting part are both larger than the sectional area of the fusing part, the first connecting part is connected with the battery cell main body, and the second connecting part is connected with the end, located in the shell, of the pole; the minimum sectional area of the fusing part is S1 mm, the surface area of the conducting bar is S2 mm, the thickness of the conducting bar is T1 mm, and S1 * S2 * T1 is larger than or equal to 9600 and smaller than or equal to 32,000. According to the invention, the fusing part can be fused under the originally set current threshold value, so that the safety of the battery pack is ensured.

Description

Technical Field

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

[0002] At present, since the commercialization of lithium-ion power batteries, they have been rapidly and widely used in various electrical equipment due to their many advantages such as light weight, high voltage, small size, no memory effect, high specific energy, long cycle life and environmental friendliness.

[0003] In order to ensure the safety of the battery, conventional batteries are provided with a fuse at the tab. In the event of a short circuit, the short circuit current is greater than the fusing current of the fuse, so that the fuse melts and cuts off the connection with the battery cell.

[0004] However, in the battery pack, since the pole tab is connected to the pole and the heat-conducting bar is connected to the pole, the heat at the pole tab will be transferred to the heat-conducting bar. Under the heat dissipation of the heat-conducting bar, the fuse will not melt under the originally set current threshold, thereby affecting the safety of the battery pack. Summary of the invention

[0005] The purpose of the present invention is to provide a battery pack to ensure that the fuse part of the tab can be more accurately fused under the originally set current threshold value to ensure safety.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: A battery pack includes a plurality of batteries, wherein the batteries include: a housing having an opening; A cover plate, the cover plate is arranged on the opening, and a through hole is formed on the cover plate; A pole, wherein the pole is at least partially disposed in the through hole; A battery cell, wherein the battery cell comprises a battery cell body and a pole ear, wherein the battery cell body is arranged in the shell, and the pole ear comprises a first connection part, a fuse part and a second connection part which are connected in sequence, and the cross-sectional areas of the first connection part and the second connection part are both larger than the cross-sectional area of ​​the fuse part, the first connection part is connected to the battery cell body, and the second connection part is connected to the end of the pole located in the shell; A conductive bar, the conductive bar being electrically connected to a side of the pole facing away from the battery cell; The minimum cross-sectional area of ​​the fuse portion is S1 mm², the surface area of ​​the conductive bar is S2 mm², and the thickness of the conductive bar is T1 mm, wherein 9600≤S1*S2*T1≤320000.

[0007] Compared with the prior art, the battery pack according to the embodiment of the present invention has the following beneficial effects: In the present invention, the smaller the minimum cross-sectional area of ​​the fuse part of the pole ear, the greater its resistance, and the greater the heat generated at the same overcurrent, so the minimum cross-sectional area of ​​the fuse part of the pole ear determines the melting current threshold of the fuse part, the first connecting part of the pole ear is connected to the battery body, the second connecting part of the pole ear is welded to the end of the pole column located inside the shell, and the conductive bar is connected to the end of the pole column located outside the shell, so the heat of the battery body can be transferred to the conductive bar through the pole ear. Since the conductive bar has the function of heat dissipation and can absorb the heat at the fuse part of the pole ear, it will cause the fuse part to not melt within the originally set current threshold. At the same time, the larger the volume of the conductive bar, the greater the heat absorbed by the conductive bar from the fuse part, and generally the conductive bar has a fixed material, a fixed specific heat capacity and a fixed density, so the heat that the conductive bar can absorb also mainly depends on the volume of the conductive bar. Therefore, in order to ensure that the fuse part can melt within the set current threshold, when the volume of the conductive bar is larger, the minimum cross-sectional area of ​​the fuse part The smaller the area, the greater the error in the maximum current that the fuse can withstand due to the heat dissipation of the conductive bar. Therefore, the minimum cross-sectional area of ​​the fuse is set to S1mm², the surface area of ​​the conductive bar is set to S2mm², and the thickness of the conductive bar is set to T1mm, wherein 9600≤S1*S2*T1≤320000. When the value of S1*S2*T1 is greater than 320000, it means that the heat absorption of the conductive bar is large, and the minimum cross-sectional area of ​​the fuse is also large, which will cause the fuse to not fuse within the set current threshold. When the value of S1*S2*T1 is less than 9600, it means that the heat absorption of the conductive bar is small, and the minimum cross-sectional area of ​​the fuse is also small, which will cause the fuse to easily fuse before reaching the set current threshold, and the fuse time does not meet the requirements. Therefore, keeping S1*S2*T1 between 9600-320000 can allow the fuse to fuse under the original set current threshold, thereby ensuring the safety of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic structural diagram of a battery according to an embodiment of the present invention; Figure 2 is a schematic diagram of a battery cell, a cover plate and a conductive bar according to an embodiment of the present invention; Figure 3 is another schematic diagram of a battery cell, a cover plate and a conductive bar according to an embodiment of the present invention; Figure 4 is a front view of a battery cell according to an embodiment of the present invention; Figure 5 is a side view of a battery cell according to an embodiment of the present invention; Figure 6 Schematic diagram of the relationship between the battery body, the tabs, the poles and the conductive bars according to an embodiment of the present invention; Figure 7It is a schematic diagram of the dimensions of a battery cell body, a terminal lug, a terminal column and a conductive bar in an embodiment of the present invention; Figure 8 It is another schematic diagram of the dimensions of the battery body, the tabs, the poles and the conductive bars in an embodiment of the present invention; Fig. 9 is a top view of a conductive bar according to an embodiment of the present invention; Fig.10 is a front view of a conductive bar according to an embodiment of the present invention; Fig.11 is a schematic diagram of the relationship between the flexible circuit substrate and the conductive bar according to an embodiment of the present invention; Fig.12 It is a schematic diagram of the relationship between the insulating film and the tab in an embodiment of the present invention.

[0009] In the figure, 100, housing; 200, cover plate; 300, first weld mark; 400, second weld mark; 500, third weld mark; 1. Battery body; 2. Tab; 21. First connection portion; 22. Fusing portion; 23. Second connection portion; 3. Pole; 4. Conductive bar; 41. Buffer slot; 5. flexible circuit substrate; 51. circuit trace; 52. fuse; 53. cantilever portion; 6. Temperature collection unit; 7. Conductive connecting piece; 8. Insulating film. DETAILED DESCRIPTION

[0010] The specific implementation of the present invention is further described in detail below in conjunction with 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.

[0011] In the description of the present invention, it should be understood that the wording "comprising" used in the present specification refers to the presence of the features, integers, steps, operations, parts / components and / or assemblies, but does not exclude the presence or addition of one or more other features, integers, steps, operations, parts / components, assemblies and / or their groups. It should be understood that when we say a part / component is "connected" to another part / component, it can be directly connected to the other part / component, or there can be intermediate parts / components. The wording "and / or" used here includes all or any unit and all combinations of one or more associated listed items.

[0012] like Figures 1 to 12 As shown, the present invention relates to a battery pack, including a plurality of batteries, wherein the battery includes: a housing 100, a cover plate 200, a pole 3, a conductive bar 4 and a battery cell.

[0013] The shell 100 has an opening; the cover plate 200 is covered on the opening, and a through hole is formed on the cover plate 200; the pole 3 is at least partially disposed in the through hole; and the conductive bar 4 is electrically connected to a side of the pole 3 facing away from the battery cell.

[0014] The battery cell includes a battery cell body 1 and a pole ear 2, wherein the battery cell body 1 is arranged in the housing 100, and the pole ear 2 includes a first connecting portion 21, a fuse portion 22 and a second connecting portion 23 which are connected in sequence, and the cross-sectional areas of the first connecting portion 21 and the second connecting portion 23 are both larger than the cross-sectional area of ​​the fuse portion 22, the first connecting portion 21 is connected to the battery cell body 1, and the second connecting portion 23 is connected to the end of the pole 3 located in the housing 100, and the minimum cross-sectional area of ​​the fuse portion is S1mm², S1=[4, 20] mm², S1 can be 6mm², 8mm², 10mm², 12mm², 14mm², 16mm² or 18mm², the surface area of ​​the conductive bar is S2mm², S2=[1200, 4000]mm², S2 can be 1600mm², 2000mm², 2400mm², 2800mm², 3200mm² or 3600mm², the thickness of the conductive bar is T1mm, T1=[2,4]mm, T1 can be 2.5mm, 3mm or 3.5mm, wherein 9600≤S1*S2*T1≤320000.

[0015] In the present invention, the smaller the minimum cross-sectional area of ​​the fuse part 22 of the pole lug 2, the greater its resistance, and the greater the heat generated at the same overcurrent, so the minimum cross-sectional area of ​​the fuse part 22 of the pole lug 2 determines the fuse current threshold of the fuse part 22, the first connecting part 21 of the pole lug 2 is connected to the battery body 1, the second connecting part 23 of the pole lug 2 is welded to the end of the pole 3 located inside the shell 100, and the conductive bar 4 is connected to the end of the pole 3 located outside the shell 100, so the heat of the battery body 1 can be transferred to the conductive bar 4 through the pole lug 2. At the conductive bar 4, since the conductive bar 4 has the function of heat dissipation and can absorb the heat at the fuse part 22 of the pole ear 2, the fuse part 22 will not be melted within the originally set current threshold. At the same time, the larger the volume of the conductive bar 4, the greater the heat absorbed by the conductive bar 4. In general, the conductive bar 4 has a fixed material, a fixed specific heat capacity and a fixed density, so the heat that the conductive bar 4 can absorb also mainly depends on the volume of the conductive bar 4. Therefore, in order to ensure that the fuse part 22 can be melted within the set current threshold, the volume of the conductive bar 4 is When the value of S1*S2*T1 is greater than 320000, it means that the heat absorption of the conductive bar 4 is large, and the minimum cross-sectional area of ​​the fuse part 22 is large. The cross-sectional area is also large, which will cause the fuse part 22 to not blow within the set current threshold. When the value of S1*S2*T1 is less than 9600, it means that the heat absorption of the conductive bar 4 is small, and the minimum cross-sectional area of ​​the fuse part 22 is also small, which will cause the fuse part 22 to easily blow before reaching the set current threshold, and the blowing time does not meet the requirements. Therefore, keeping S1*S2*T1 between 9600-320000 can make the fuse part 22 blow under the originally set current threshold, thereby ensuring the safety of the battery pack.

[0016] It should be noted that, since the thickness of the conductive bar 4 is relatively small, and the ratio of the conductive bar 4 to the surface area of ​​the conductive bar 4 is also relatively small, the volume of the conductive bar 4 can be S2*T1.

[0017] In this embodiment, on the path of heat transfer from the battery cell to the conductive bar 4, the distance between the fuse 22 and the conductive bar 4 is L1 mm, wherein 6 mm ≤ L1 ≤ 18 mm, and L1 may be 8 mm, 10 mm, 12 mm, 14 mm or 16 mm.

[0018] When the fuse part 22 is too close to the conductive bar 4, the heat transfer path between the two is short, so that the conductive bar 4 absorbs more heat from the fuse part 22, making the heat dissipation efficiency higher, and when the conductive bar 4 vibrates, it is also easy to transfer the vibration energy to the fuse part 22, causing the fuse part 22 to easily break. When the fuse part 22 is too far from the conductive bar 4, the distance between the fuse part 22 and the battery body 1 is closer, and the heat of the fuse part 22 is easy to damage the battery body 1. Therefore, keeping L1 at 6-18mm can ensure the stability of the structure of the fuse part 22 itself and avoid affecting the battery body 1.

[0019] In this embodiment, the minimum cross-sectional area of ​​the conductive bar 4 is S3 mm², S3=[60, 150] mm², S3 can be 80 mm², 100 mm², 120 mm² or 140 mm², wherein 3≤S3 / S1≤37.5.

[0020] When S3 / S1 is less than 3, that is, the ratio of the minimum cross-sectional area of ​​the conductive bar 4 to the minimum cross-sectional area of ​​the fuse 22 is too small, it is easy to cause the conductive bar 4 to fuse before the fuse 22, making the fuse 22 ineffective and the battery pack unprotected.

[0021] In this embodiment, the conductive bar 4 and the pole 3 are welded to form a first weld mark 300, and the area of ​​the first weld mark 300 is S4 mm², S4=[60,150] mm², S4 can be 80 mm², 100 mm², 120 mm² or 140 mm², wherein 240≤S4*S1≤3000.

[0022] The conductive bar 4 and the pole 3 are welded, and a first weld mark 300 is formed between the two. Since it is easier to transfer heat at the welding position of the conductive bar 4 and the pole 3, the larger the area of ​​the first weld mark 300, the higher the heat absorption efficiency of the conductive bar 4, and the smaller the minimum cross-sectional area of ​​the fuse 22 should be designed, otherwise the fuse 22 is not easy to be melted at the set current threshold. Therefore, S4*S1 is kept between 240-3000, so as to ensure that the fuse 22 is melted at the original set current threshold, thereby ensuring the safety of the battery pack.

[0023] In this embodiment, the contact area between the conductive bar 4 and the pole 3 is S5 mm², S5=[100,500] mm², S5 can be 150 mm², 200 mm², 250 mm², 300 mm², 350 mm², 400 mm² or 450 mm², wherein 400≤S5*S1≤10000.

[0024] Since the contact surfaces of the conductive bar 4 and the pole 3 will transfer heat, and the larger the contact area between the two, the larger the cross-sectional area of ​​the heat transfer path, the higher the heat transfer efficiency. Therefore, in order to ensure that the fuse part 22 melts under the originally set current threshold, the minimum cross-sectional area of ​​the fuse part 22 should be designed to be smaller. Therefore, S5*S1 is maintained between 400-10000 to ensure the safety of the battery pack.

[0025] In this embodiment, the conductive bar 4 is connected to the plurality of poles 3, and a buffer groove 41 is provided on the conductive bar 4 and in an area between two adjacent poles 3, the width of the buffer groove 41 is W1 mm, and the depth of the buffer groove 41 is D mm, wherein W1*D=[6,12]mm², 0.3≤(W1*D) / S1≤3.

[0026] By providing a buffer slot 41 on the conductive bar 4, and the buffer slot 41 is located between two adjacent poles 3, that is, the buffer slot 41 is located between two adjacent battery cells, so that when the battery cell vibrates, it can play a buffering role, thereby reducing the vibration transmitted to the pole ear 2, so that the fuse 22 is not easily vibrated and causes the fuse 22 to break. Since the smaller the minimum cross-sectional area of ​​the fuse 22, the more fragile the fuse 22, so the greater the buffering capacity required for the fuse 22, and the buffering capacity of the buffer slot 41 is related to the width and depth of the buffer slot 41, the larger the width and depth of the buffer slot 41, the stronger the buffering capacity, so let (W1*D) / S1 be kept between 0.3-3 to ensure that the fuse 22 is not easy to break.

[0027] In this embodiment, the battery pack further includes a flexible circuit substrate 5 and a temperature acquisition unit 6 disposed on the conductive bar 4, the temperature acquisition unit 6 is electrically connected to the flexible circuit substrate 5, and on the path of heat transfer from the battery cell to the temperature acquisition unit 6, the distance between the temperature acquisition unit 6 and the fuse 22 is L2 mm, wherein 6.5 mm ≤ L2 ≤ 20 mm. L2 can be 8 mm, 10 mm, 12 mm, 14 mm, 16 mm or 18 mm.

[0028] By setting the temperature acquisition unit 6, the temperature of the conductive bar 4 can be collected, and on the path of heat transfer from the battery cell to the temperature acquisition unit 6, the distance between the temperature acquisition unit 6 and the fuse part 22 is 6.5mm≤L2≤20mm, so that the temperature acquisition unit 6 is closer to the fuse part 22, so that the temperature monitored by the temperature acquisition unit 6 is closer to the temperature of the fuse part 22, so as to facilitate timely control by the battery management system. The temperature acquisition unit 6 can be a thermistor sensor.

[0029] Preferably, on the path of heat transfer from the battery cell to the temperature collection unit 6, the distance between the temperature collection unit 6 and the pole 3 is L3 mm, wherein 0.5 mm ≤ L3 ≤ 12 mm. L3 may be 2 mm, 4 mm, 6 mm, 8 mm or 10 mm.

[0030] On the path of heat transfer from the battery cell to the temperature collection unit 6, the distance between the temperature collection unit 6 and the pole 3 is 0.5mm≤L3≤12mm to avoid the temperature collection unit 6 and the pole 3 being too close, so that the conductive bar 4 and the pole 3 are not easily interfered during assembly, and the temperature collection unit 6 and the pole 3 are not too far away, which affects the accuracy of temperature collection.

[0031] Furthermore, the battery pack further comprises a conductive connecting piece 7, the conductive connecting piece 7 is connected to the conductive bar 4, the flexible circuit substrate 5 is provided with a circuit trace 51, the conductive connecting piece 7 is connected to the circuit trace 51, the circuit trace 51 is provided with a fuse 52, and on the path of heat transfer from the battery cell to the flexible circuit substrate 5, the distance between the fuse 52 and the fuse part 22 is L4mm, wherein 6.5mm≤L4≤20mm. L4 can be 8mm, 10mm, 12mm, 14mm, 16mm or 18mm.

[0032] Since the heat of the fuse part 22 can be transferred through the pole 3, the conductive bar 4, the conductive connecting piece 7 and the circuit trace 51, so that the heat can be transferred to the flexible circuit substrate 5, when the fuse 52 is too close to the fuse part 22 on the path of heat transfer from the battery cell to the flexible circuit substrate 5, it is easy to cause the fuse 52 on the flexible circuit substrate 5 to be heated and melted first. When the fuse 52 is too far from the fuse part 22, the heat transfer path between the fuse part 22 and the fuse 52 is too long, and the heat of the fuse part 22 is lost more on the heat transfer path, which is easy to affect the melting of the fuse 52. Therefore, the distance L4 between the fuse 52 and the fuse part 22 is kept between 6.5-20mm to ensure the normal use of the fuse 52. The conductive connecting piece 7 can be a nickel sheet.

[0033] Furthermore, the flexible circuit substrate 5 has a cantilever portion 53 extending outward, the circuit trace 51 extends to the cantilever portion 53, one end of the conductive connecting piece 7 is attached to the conductive row 4, and the other end is arranged on the cantilever portion 53 and connected to the circuit trace 51 on the cantilever portion 53, and the fuse 52 is arranged on the circuit trace 51 of the cantilever portion 53.

[0034] That is, the fuse 52 is arranged on the cantilever portion 53 , and the cantilever portion 53 can prevent the fuse 52 from contacting the heated conductive bar 4 and the pole 3 , thereby minimizing the heat transfer to the fuse 52 .

[0035] In this embodiment, the number of the battery cell bodies 1 is n, and the conductive bar 4 is connected to the poles 3 corresponding to the n battery cell bodies 1 , wherein n=[2,400], 24≤((S2*T1) / n)*S1≤160000.

[0036] Since the conductive bar 4 is electrically connected to the poles 3 corresponding to the n battery cell bodies 1, one conductive bar 4 simultaneously absorbs the heat transferred by the fuse parts 22 of the pole ears 2 corresponding to the n battery cell bodies 1. Therefore, the volume of the conductive bar 4 can be divided into multiple parts according to the number of battery cell bodies 1. Therefore, in order to ensure that the fuse part 22 can be melted under the originally set current threshold, it is necessary to make 24≤S1*(V1 / n)≤160000.

[0037] In one embodiment, the battery cell is a wound battery cell, and the pole lug 2 includes a plurality of pole lug sheets stacked together, and the pole lug sheet includes a first sub-connection portion, a sub-fuse portion and a second sub-connection portion connected in sequence, all the first sub-connection portions of the pole lug 2 are stacked together to form the first connection portion 21, all the second sub-connection portions of the pole lug 2 are stacked together to form the second connection portion 23, all the sub-fuse portions of the pole lug 2 are welded together to form the fuse portion 22, and a second weld mark 400 is formed on the side of the pole lug 2.

[0038] Since the pole tab 2 includes a plurality of pole tab sheets stacked together, the pole tab sheet includes a first sub-connection portion, a sub-fuse portion, and a second sub-connection portion connected in sequence, the first sub-connection portion is connected to the battery cell body 1, the second sub-connection portion is welded to the pole 3, the second sub-connection portions of the plurality of pole tab sheets are welded together and welded to the pole 3, and then the plurality of sub-fuse portions of the plurality of pole tab sheets are welded together, so that when the set current threshold is reached, the plurality of sub-fuse portions can be ensured to be blown at the same time to smoothly cut off the electrical connection between the battery cell body 1 and the pole 3. If the sub-fuse portions of the plurality of pole tab sheets are separated from each other, then when the fuse portion 22 is blown, some of the sub-fuse portions may not be blown, and the blown sub-fuse portions may be re-lapped and adhered to the pole tab sheet that has not been blown, which is equivalent to the battery cell body 1 and the pole 3 still not being electrically connected, and the large current protection function of the fuse portion 22 cannot be achieved.

[0039] In one embodiment, partial areas of all sub-fusible parts of the tab 2 are welded together, and the area of ​​the second weld mark 400 is smaller than the area of ​​the side surface of the fuse part 22, so as to prevent overlapping and adhesion between the fused and unfused sub-fusible parts.

[0040] In another embodiment, all areas of all sub-fusible parts of the tab 2 are welded together, and the area of ​​the second weld mark 400 is equal to the area of ​​the side surface of the fuse part 22, so as to prevent overlapping and adhesion between the fused and unfused sub-fusible parts.

[0041] In other embodiments, all areas of all sub-fusible parts of the tab 2 are welded together, the area of ​​the second weld mark 400 is larger than the area of ​​the side of the fuse part 22, and the second weld mark 400 completely covers the fuse part 22. This can also prevent the problem of overlapping and sticking between the fused and unfused sub-fusible parts.

[0042] Specifically, the area of ​​the pole tab between the first sub-connection portion and the second sub-connection portion can be welded together first, and then the welding area can be cut or punched to reduce the cross-sectional area of ​​the welding area, thereby forming the fuse portion 22 at the position of the smallest cross-sectional area, so as to improve assembly efficiency and avoid the need to cut multiple pole tabs individually.

[0043] Preferably, the second weld mark 400 is formed on the side of the outermost tab sheet, and on the path of heat transfer from the battery cell to the conductive bar 4, the distance between one end of the second weld mark 400 close to the second sub-connection portion and one end of the sub-fuse portion of the tab sheet close to the second sub-connection portion is L5 mm, wherein 1 mm ≤ L5 ≤ 8 mm. L5 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm.

[0044] On the path of heat transfer from the battery cell to the conductive bar 4, when the distance between one end of the second weld mark 400 close to the second sub-connection portion and one end of the sub-fuse portion of the pole tab sheet close to the second sub-connection portion is too large, it means that the second weld mark 400 is too close to the weld mark between the pole tab 2 and the pole 3, and due to assembly tolerance, the two weld marks may overlap, resulting in secondary repeated welding, and the strength of the part after two welds will decrease, making the pole tab 2 easy to break, and also causing deviation in the maximum current threshold of the fuse 22; If the distance between the end of the second weld mark 400 close to the second sub-connection part and the end of the sub-fuse part of the pole tab close to the second sub-connection part is too small, the multiple sub-fuse parts of the multiple pole tabs far away from the welding equipment area of ​​the pole tab 2 may not be completely welded together, resulting in partial area separation. Therefore, when the multiple sub-fuse parts of the multiple pole tabs reach the original set current threshold and fuse, the multiple sub-fuse parts may still be bonded, which is equivalent to the battery body 1 and the pole 3 still not cutting off the electrical connection, and the high current protection function of the fuse part 22 cannot be achieved. Therefore, keeping the distance L5 between the end of the second weld mark 400 close to the second sub-connection part and the end of the sub-fuse part of the pole tab close to the second sub-connection part between 1-8 mm is conducive to ensuring the safety of the battery pack.

[0045] Furthermore, the second weld mark 400 is formed on the side of the outermost tab sheet, and on the path of heat transfer from the battery cell to the conductive bar 4, the distance between one end of the second weld mark 400 close to the first sub-connection portion and one end of the sub-fuse portion of the tab sheet close to the first sub-connection portion is L6 mm, wherein 1 mm ≤ L6 ≤ 8 mm. L6 can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm or 7 mm.

[0046] On the path of heat transfer from the battery cell to the conductive bar 4, when the distance between one end of the second weld mark 400 close to the first sub-connection part and one end of the sub-fuse part of the pole tab sheet close to the first sub-connection part is too large, it means that the second weld mark 400 is too close to the battery cell body 1, which is equivalent to that when the sub-fuse parts of multiple pole tab sheets are welded together, the high temperature generated by welding may burn the battery cell body 1, causing the loss of electrical performance of the battery cell body 1 or thermal safety risk; if the distance between one end of the second weld mark 400 close to the first sub-connection part and one end of the sub-fuse part of the pole tab sheet close to the first sub-connection part is too small, it is possible that the multiple sub-fuse parts of multiple pole tab sheets in the area where the pole tab 2 is far away from the welding equipment are not completely welded together, resulting in partial area separation, so that when the multiple sub-fuse parts of the multiple pole tab sheets reach the originally set current threshold and fuse, the multiple sub-fuse parts may still be bonded to each other, which is equivalent to that the electrical connection between the battery cell body 1 and the pole 3 is still not cut off, and the high current protection function of the fuse part 22 cannot be achieved. Therefore, maintaining the distance L6 between the end of the second weld mark 400 close to the first sub-connection portion and the end of the sub-fuse portion of the tab close to the first sub-connection portion between 1-8 mm is beneficial to ensuring the safety of the battery pack.

[0047] The second connection portion 23 is welded to the end of the pole 3 located in the housing 100 to form a third weld mark 500. On the path of heat transfer from the battery cell to the conductive bar 4, the distance between the second weld mark 400 and the third weld mark 500 is L7 mm, where 1 mm ≤ L7 ≤ 5 mm. L7 can be 2 mm, 3 mm or 4 mm.

[0048] That is, the third weld mark 500 formed by connecting the second connection portion 23 of the pole tab 2 and the pole column 3 and the second weld mark 400 on the pole tab 2 are kept at a distance, so that the multiple pole tab sheets of the pole tab 2 located between the second weld mark 400 and the third weld mark 500 are dispersed, so as to play a role in buffering and pulling, so as to ensure that the vibration is not easily transmitted to the fuse part 22 of the pole tab 2 through the pole column 3, and the fuse part 22 is not easily broken. In addition, the distance L7 between the second weld mark 400 and the third weld mark 500 is maintained between 1-5mm, so that the third weld mark 500 and the second weld mark 400 are not too close to each other, so as to have a buffering effect, and the second weld mark 400 is not too close to the battery body 1, so as to avoid the temperature during welding affecting the battery body 1.

[0049] Preferably, on the path of heat transfer from the battery cell to the conductive bar 4, the distance between one end of the fuse part 22 away from the first connection part 21 and one end of the fuse part 22 close to the first connection part 21 is L8mm, L8=[2,8]mm, L8 can be 3mm, 5mm or 7mm, wherein 0.4≤L8 / L7≤8.

[0050] On the path of heat transfer from the electrode ear 2 to the conductive bar 4, when the ratio of the distance L8 between the end of the fuse part 22 away from the first connection part 21 and the end of the fuse part 22 close to the first connection part 21 to the distance L7 between the second weld mark 400 and the third weld mark 500 is too large, it means that the length of the fuse part 22 is large and it is easy to break due to vibration, while the distance between the second weld mark 400 and the third weld mark 500 is short, and the buffering capacity provided is weak, so that the fuse part 22 is easy to break; when the ratio of the distance L8 between the end of the fuse part 22 away from the first connection part 21 and the end of the fuse part 22 close to the first connection part 21 to the distance L7 between the second weld mark 400 and the third weld mark 500 is too small, it means that the length of the fuse part 22 is small, and the distance between the second weld mark 400 and the third weld mark 500 is long, which will cause the fuse part 22 to fail to meet the requirements of the melting time. Therefore, maintaining L8 / L7 between 0.4 and 8 can ensure smooth use of the fuse 22.

[0051] In other embodiments, the second connection portion 23 is welded to the end of the pole 3 located in the housing 100 to form a third weld mark 500 , and the second weld mark 400 and the third weld mark 500 are connected together.

[0052] That is, a line is welded directly on the pole lug 2, a long strip is welded when welding the pole lug 2 and the pole 3, and then the welded area is cut to form the fuse part 22, which can improve the assembly efficiency.

[0053] In other embodiments, the battery cell is a stacked battery cell, the pole lug 2 includes a plurality of pole lug sheets stacked together, the pole lug sheet includes a first sub-connection portion, a sub-fuse portion and a second sub-connection portion connected in sequence, and the sub-fuse portions of the plurality of pole lug sheets are spaced apart from each other.

[0054] Since the multiple pole tabs of the stacked battery cell are individually connected to the pole tabs in the multiple battery cell bodies 1, the sub-fuse parts of the multiple pole tabs can be separately arranged, and the pole tabs on the pole tabs with problems can be individually fused.

[0055] In this embodiment, the second connection portion 23 is welded to the end of the pole 3 located in the housing 100 to form a third weld mark 500. On the path of heat transfer from the battery cell to the conductive bar 4, the distance between the fuse portion 22 and the third weld mark 500 is L9 mm, where 1 mm ≤ L9 ≤ 10 mm. L9 can be 2 mm, 4 mm, 6 mm or 8 mm.

[0056] On the path of heat transfer from the pole tab 2 to the conductive bar 4, if the distance between the fuse part 22 and the third weld mark 500 is too small, the heat of welding the pole tab 2 and the pole 3 may affect the fuse part 22, causing partial melting, and the fuse part 22 is too close to the pole 3, and is also easily pulled or vibrated and broken, affecting the performance of the fuse part 22; when the distance between the fuse part 22 and the third weld mark 500 is too large, it is equivalent to the fuse part 22 being far away from the pole 3 and close to the battery body 1, which is easy to affect the performance of the battery body 1. Therefore, the distance L9 between the fuse part 22 and the third weld mark 500 is maintained between 1-10mm to ensure the performance of the battery pack.

[0057] In this embodiment, the second connecting portion 23 is welded to the end of the pole 3 located in the shell 100 to form a third weld mark 500, and the area of ​​the third weld mark 500 is S6 mm², S6=[10,80] mm², S6 can be 20 mm², 40 mm² or 60 mm², wherein 0.00062≤S6 / (S2*T1)≤0.033.

[0058] When the pole lug 2 and the pole post 3 are welded, in order to prevent more heat from being transferred to the fuse part 22 and causing the fuse part 22 to melt, the heat can be dissipated through the conductive bar 4. The volume of the conductive bar 4 is related to the heat dissipation efficiency, so the ratio of the area of ​​the third weld mark 500 of the pole lug 2 and the pole post 3 to the volume of the conductive bar 4 is set between 0.00062-0.033. Therefore, on the premise that the volume of the conductive bar 4 meets the assembly conditions, the volume of the conductive bar 4 is increased to achieve a better heat dissipation effect, thereby reducing the impact on the fuse part 22.

[0059] In this embodiment, the battery pack further includes an insulating film 8 , and the insulating film 8 is provided on at least one side of the pole tab 2 in the first direction, so as to protect the pole tab 2 .

[0060] Preferably, the insulating film 8 covers the region of the fuse portion 22 of the tab 2, thereby protecting the fuse portion 22 from corrosion by the electrolyte or other impurities, and ensuring the accuracy of the fuse threshold of the fuse portion 22.

[0061] Furthermore, the insulating film 8 extends to the region of the first connecting portion 21 , that is, the insulating film 8 extends to the root of the pole tab 2 , thereby further preventing the pole tab 2 from being torn.

[0062] Furthermore, the insulating film 8 extends to the area of ​​the second connecting portion 23 , that is, the insulating film 8 extends to the area where the pole tab 2 and the pole 3 are welded, so as to provide corrosion protection for the third weld mark 500 .

[0063] In this embodiment, the distance between the two sides of the insulating film 8 in the second direction is W2mm, that is, the width of the insulating film 8 is W2mm, and the distance between the two sides of the pole ear 2 in the second direction is W3mm, that is, the width of the pole ear 2 is W3mm, wherein 1.1≤W2 / W3≤1.5, and the second direction is perpendicular to the first direction.

[0064] That is, the ratio of the width of the insulating film 8 to the width of the pole lug 2 is between 1.1-1.5, so the width of the insulating film 8 can be greater than the width of the pole lug 2, so that the insulating film 8 can fully protect the pole lug 2 to prevent the pole lug 2 from breaking and being corroded. At the same time, the width of the insulating film 8 will not be too large to occupy too much space.

[0065] In one embodiment, two opposite sides of the pole lug 2 are covered with the insulating film 8 to more comprehensively protect the pole lug 2 and prevent the pole lug 2 from being torn and corroded.

[0066] Preferably, one side of the pole tab 2 in the first direction is a welding surface, a welding area is provided on the welding surface, and the other side of the pole tab 2 in the first direction and a region corresponding to the welding area are not covered with the insulating film 8 .

[0067] At present, when the insulating film 8 is assembled, a layer of insulating film 8 is first pasted on the side of the pole lug 2 away from the welding surface, and then the pole lug 2 is welded. After the welding is completed, another layer of insulating film 8 is pasted on the welding surface of the pole lug 2, thereby completing the attachment of the insulating film 8 to both sides of the pole lug 2 in the first direction. However, since the insulating film 8 is pasted on the side of the pole lug 2 away from the welding surface, it is easy to explode during welding, resulting in poor welding of the pole lug 2. Therefore, the insulating film 8 located on the side of the pole lug 2 away from the welding surface and corresponding to the welding area needs to be hollowed out.

[0068] In this embodiment, the distance between the two sides of the pole ear 2 in the first direction is T2mm, that is, the thickness of the pole ear 2 is T2mm, 0.004mm≤T2≤0.02mm, T2 can be 0.008mm, 0.012mm or 0.016mm, the resistivity of the pole ear 2 is ρΩ·m, 1.5*10^-8Ω·m≤ρ≤3*10^-8Ω·m, and on the connection path between the pole ear 2 and the battery body 1, the distance between the end of the fuse 22 close to the first connection part 21 and the end away from the first connection part 21 is L 10 mm, that is, the length of the fuse 22 is L 10 mm, 2mm≤L 10 ≤8mm.L 10 It can be 3mm, 5mm or 7mm.

[0069] In this embodiment, on the connection path between the tab 2 and the battery body 1, the distance between the fuse 22 and the battery body 1 is L 11 mm, where 5 mm ≤ L 11 ≤20mm.L 11 It can be 7mm, 9mm, 11mm, 13mm, 15mm, 17mm or 19mm.

[0070] On the connection path between the tab 2 and the battery body 1, the distance L between the fuse part 22 and the battery body 1 is 11 The distance between the fuse part 22 and the battery body 1 is kept between 5-20mm, so that the distance between the fuse part 22 and the battery body 1 will not be too close, so as to avoid the heat of the fuse part 22 damaging the battery body 1, and the distance between the fuse part 22 and the pole 3 will not be too close, so as to avoid the pole 3 vibrating and easily involving the fuse part 22, causing the fuse part 22 to tear.

[0071] Preferably, the battery body 1 has an active material layer inside, and on the connection path between the tab 2 and the battery body 1, the distance between the fuse 22 and the active material layer in the battery body 1 is L 12 mm, where 6.5 mm ≤ L 12 ≤21.5mm.L 12It can be 9mm, 12mm, 15mm or 18mm.

[0072] On the connection path between the tab 2 and the cell body 1, the distance L between the fuse 22 and the active material layer in the cell body 1 is 12 Maintained between 6.5-21.5mm, on the one hand, the fuse part 22 will not be too close to the active material layer of the battery body 1, and the temperature difference between the active material layer near the fuse part 22 and the active material layer not near the fuse part 22 will not be too large, thereby preventing the local resistance of the battery body 1 from being different, causing problems such as uneven lithium insertion and aging state differences, and preventing the fuse part 22 from overheating and causing part of the active material to be inactivated, that is, losing the ability to embed and extract lithium ions, thereby causing lithium precipitation, black spots and other problems; on the other hand, the distance between the fuse part 22 and the pole 3 will not be too close, so as to avoid the pole 3 from easily involving the fuse part 22 when vibrating, causing the fuse part 22 to be torn.

[0073] Furthermore, the battery cell body 1 has a tab glue inside, and on the connection path between the tab 2 and the battery cell body 1, the distance between the fuse 22 and the tab glue inside the battery cell body 1 is L 13 mm, where 7 mm ≤ L 13 ≤22mm.L 13 It can be 9mm, 11mm, 13mm, 15mm, 17mm, 19mm or 21mm.

[0074] The ear glue is made of PVDF and Al2O3, so the ear glue also has a certain high temperature resistance. However, the instantaneous temperature when the fuse part 22 is melted is also high, and the melting point can reach 660 degrees. Therefore, in the connection path between the ear 2 and the battery body 1, when the fuse part 22 is too close to the ear glue, the ear glue will be burned and fail, causing a short circuit between the positive electrode foil and the negative electrode material area, and the risk of thermal runaway of the battery body 1 will be greatly increased. When the distance between the fuse part 22 and the pole 3 is too close, the vibration of the pole 3 is easy to involve the fuse part 22, causing the fuse part 22 to tear. Therefore, the distance L between the fuse part 22 and the ear glue in the battery body 1 is set to 1. 13 Keep it between 7-22mm to ensure the performance of the battery body 1.

[0075] Furthermore, the cell body 1 has a diaphragm inside, and on the connection path between the tab 2 and the cell body 1, the distance between the fuse 22 and the diaphragm inside the cell body 1 is L 14 mm, where 5 mm ≤ L 14 ≤20mm.L 14 It can be 7mm, 9mm, 11mm, 13mm, 15mm, 17mm or 19mm.

[0076] Since the diaphragm in the battery body 1 is not heat-resistant, when the distance between the fuse part 22 and the diaphragm is close on the connection path between the pole ear 2 and the battery body 1, it is easy to cause the diaphragm to burn, thereby causing a short circuit between the positive electrode foil and the negative electrode material area, and the risk of thermal runaway of the battery body 1 is greatly increased. When the distance between the fuse part 22 and the pole 3 is too close on the connection path between the pole ear 2 and the battery body 1, the vibration of the pole 3 is easy to involve the fuse part 22, causing the fuse part 22 to tear. Therefore, the distance L between the fuse part 22 and the pole ear glue in the battery body 1 is 14 Maintain between 5 and 20 to ensure the performance of the battery cell body 1.

[0077] It should be noted that, since the present invention is to reduce the influence of the heat of the fuse part 22 on the performance of the battery body 1 , the connection path between the tab 2 and the battery body 1 can also be considered as the heat transfer path between the tab 2 and the battery body 1 .

[0078] It should be emphasized that, in the present invention, the minimum cross-sectional area of ​​the fuse portion is the area of ​​the cross-section formed by breaking along a direction perpendicular to the fuse portion at the position of the minimum size of the fuse portion; the surface area of ​​the conductive bar is the sum of the areas of the outer sides of the conductive bar; the volume of the conductive bar refers to the size of the space it occupies; the minimum cross-sectional area of ​​the conductive bar is the area of ​​the cross-section formed by breaking along a direction perpendicular to the conductive bar at the position of the minimum size of the conductive bar; the areas of the first weld mark, the second weld mark and the third weld mark refer to the areas of the welding areas.

[0079] The following are the relevant test methods: Provide a test method to determine whether the fuse part of the tab meets the fuse time requirement: The pole ear includes a first connection part, a fuse part and a second connection part which are connected in sequence, the first connection part is a free end, the second connection part is welded to one end of the pole, the other end of the pole is welded to the conductive bar, one electrical connection end of the current source test equipment is connected to the conductive bar, the other electrical connection end of the current source test equipment is connected to the first connection part, the current source test equipment is powered on, the current is 800A, and if the fuse part blows within 10 minutes, it meets the product safety standards.

[0080] If the current is less than 800A and the fuse blows within 10 minutes, it means that the fuse does not meet the overcurrent requirement and is judged as unqualified; If the current is greater than 800A and the fuse blows after 10 minutes, it means that the fuse does not meet the fusing requirements and is judged to be unqualified.

[0081] Using the above test method, the results are shown in the following table: The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A battery pack, characterized in that: A plurality of batteries are included, the batteries comprising: a housing having an opening; A cover plate, the cover plate is arranged on the opening, and a through hole is formed on the cover plate; A pole, wherein the pole is at least partially disposed in the through hole; A battery cell, wherein the battery cell comprises a battery cell body and a pole ear, wherein the battery cell body is arranged in the shell, and the pole ear comprises a first connection part, a fuse part and a second connection part which are connected in sequence, and the cross-sectional areas of the first connection part and the second connection part are both larger than the cross-sectional area of ​​the fuse part, the first connection part is connected to the battery cell body, and the second connection part is connected to the end of the pole located in the shell; A conductive bar, the conductive bar being electrically connected to a side of the pole facing away from the battery cell; The minimum cross-sectional area of ​​the fuse portion is S1 mm², the surface area of ​​the conductive bar is S2 mm², and the thickness of the conductive bar is T1 mm, wherein 9600≤S1*S2*T1≤320000.

2. The battery pack according to claim 1, characterized in that: On the path of heat transfer from the battery cell to the conductive bar, the distance between the fuse part and the conductive bar is L1 mm, wherein 6 mm ≤ L1 ≤ 18 mm.

3. The battery pack according to claim 1, characterized in that: The minimum cross-sectional area of ​​the conductive bar is S3 mm², where 3≤S3 / S1≤37.

5.

4. The battery pack according to claim 1, characterized in that: The conductive bar and the pole are welded to form a first weld mark, and the area of ​​the first weld mark is S4 mm², wherein 240≤S4*S1≤3000.

5. The battery pack according to claim 1, characterized in that: The contact area between the conductive bar and the pole is S5 mm², wherein 400≤S5*S1≤10000.

6. The battery pack according to claim 1, characterized in that: The conductive bar is connected to the plurality of poles, and a buffer groove is provided on the conductive bar and in an area between two adjacent poles. The width of the buffer groove is W1 mm, and the depth of the buffer groove is D mm, wherein 0.3≤(W1*D) / S1≤3.

7. The battery pack according to claim 1, characterized in that: It also includes a flexible circuit substrate and a temperature collection unit arranged on the conductive bar, the temperature collection unit is electrically connected to the flexible circuit substrate, and on the path of heat transfer from the battery cell to the temperature collection unit, the distance between the temperature collection unit and the fuse part is L2mm, wherein 6.5mm≤L2≤20mm.

8. The battery pack according to claim 7, characterized in that: On the path of heat transfer from the battery cell to the temperature collection unit, the distance between the temperature collection unit and the pole is L3 mm, wherein 0.5 mm≤L3≤12 mm.

9. The battery pack according to claim 7, characterized in that: It also includes a conductive connecting piece, which is connected to the conductive row. The flexible circuit substrate is provided with a circuit trace. The conductive connecting piece is connected to the circuit trace. A fuse is provided on the circuit trace. On the path of heat transfer from the battery cell to the flexible circuit substrate, the distance between the fuse and the fuse part is L4mm, wherein 6.5mm≤L4≤20mm.

10. The battery pack according to claim 9, characterized in that: The flexible circuit substrate has a cantilever portion extending outward, the circuit trace extends to the cantilever portion, one end of the conductive connecting piece is attached to the conductive row, and the other end is arranged on the cantilever portion and connected to the circuit trace on the cantilever portion, and the fuse is arranged on the circuit trace of the cantilever portion.

11. The battery pack according to claim 1, characterized in that: The number of the battery cell bodies is n, and the conductive bar is connected to the poles corresponding to the n battery cell bodies, wherein 24≤((S2*T1) / n)*S1≤160000.

12. The battery pack according to any one of claims 1 to 11, characterized in that: The battery cell is a wound battery cell, and the pole lug includes a plurality of pole lug sheets stacked together, and the pole lug sheets include a first sub-connection portion, a sub-fuse portion, and a second sub-connection portion connected in sequence, all the first sub-connection portions of the pole lug are stacked together to form the first connection portion, all the second sub-connection portions of the pole lug are stacked together to form the second connection portion, all the sub-fuse portions of the pole lug are welded together to form the fuse portion, and a second weld mark is formed on the side of the pole lug.

13. The battery pack according to claim 12, characterized in that: Partial regions of all the sub-fuse portions of the tab are welded together.

14. The battery pack according to claim 12, characterized in that: The entire regions of all the sub-fuse portions of the tab are welded together, and the area of ​​the second weld mark is equal to or greater than the area of ​​the side surface of the fusing portion.

15. The battery pack according to claim 14, characterized in that: The second weld mark is formed on the side of the outermost pole tab sheet, and on the path of heat transfer from the battery cell to the conductive bar, the distance between one end of the second weld mark close to the second sub-connection portion and one end of the sub-fuse portion of the pole tab sheet close to the second sub-connection portion is L5mm, wherein 1mm≤L5≤8mm.

16. The battery pack according to claim 14, characterized in that: The second weld mark is formed on the side of the outermost pole tab sheet, and on the path of heat transfer from the battery cell to the conductive bar, the distance between one end of the second weld mark close to the first sub-connection part and one end of the sub-fuse part of the pole tab sheet close to the first sub-connection part is L6mm, wherein 1mm≤L6≤8mm.

17. The battery pack according to claim 12, characterized in that: The second connecting portion is welded to the end of the pole located in the shell to form a third weld mark. On the path of heat transfer from the battery cell to the conductive bar, the distance between the second weld mark and the third weld mark is L7mm, wherein 1mm≤L7≤5mm.

18. The battery pack according to claim 17, characterized in that: On the path of heat transfer from the battery cell to the conductive bar, the distance between an end of the fuse away from the first connection portion and an end of the fuse close to the first connection portion is L8 mm, wherein 0.4≤L8 / L7≤8.

19. The battery pack according to claim 12, characterized in that: The second connection portion is welded to the end of the pole located in the shell to form a third weld mark, and the second weld mark and the third weld mark are connected together.

20. The battery pack according to any one of claims 1 to 11, characterized in that: The battery cell is a laminated battery cell, the pole tab comprises a plurality of pole tab sheets stacked together, the pole tab sheet comprises a first sub-connection portion, a sub-fuse portion and a second sub-connection portion connected in sequence, and the sub-fuse portions of the plurality of pole tab sheets are spaced apart from each other.

21. The battery pack according to any one of claims 1 to 11, characterized in that: The second connecting portion is welded to the end of the pole located in the shell to form a third weld mark. On the path of heat transfer from the battery cell to the conductive bar, the distance between the fuse portion and the third weld mark is L9mm, wherein 1mm≤L9≤10mm.

22. The battery pack according to any one of claims 1 to 11, characterized in that: The second connecting portion is welded to the end of the pole located in the shell to form a third weld mark, and the area of ​​the third weld mark is S6 mm², wherein 0.00062≤S6 / (S2*T1)≤0.

033.

23. The battery pack according to any one of claims 1 to 11, characterized in that: It also includes an insulating film, and the insulating film is provided on at least one side of the electrode tab in the first direction.

24. The battery pack according to claim 23, characterized in that: The insulating film covers a region of the fusing portion of the tab.

25. The battery pack according to claim 24, characterized in that: The insulating film extends to a region of the first connecting portion and / or a region of the second connecting portion.

26. The battery pack according to claim 23, characterized in that: The distance between the two sides of the insulating film in the second direction is W2 mm, and the distance between the two sides of the tab in the second direction is W3 mm, wherein 1.1≤W2 / W3≤1.5, and the second direction is perpendicular to the first direction.

27. The battery pack according to claim 23, characterized in that: One side of the electrode tab in the first direction is a welding surface, a welding area is provided on the welding surface, and a region corresponding to the welding area on the other side of the electrode tab in the first direction is not covered with the insulating film.

28. The battery pack according to any one of claims 1 to 11, characterized in that: The distance between the two sides of the pole ear in the first direction is T2mm, 0.004mm≤T2≤0.02mm, the resistivity of the pole ear is ρΩ·m, 1.5*10^-8Ω·m≤ρ≤3*10^-8Ω·m, and on the connection path between the pole ear and the battery body, the distance between the end of the fuse part close to the first connection part and the end away from the first connection part is L 10 mm, 2mm≤L 10 ≤8mm.

29. The battery pack according to any one of claims 1 to 11, characterized in that: On the connection path between the tab and the battery body, the distance between the fuse part and the battery body is L 11 mm, where 5 mm ≤ L 11 ≤20mm.

30. The battery pack according to any one of claims 1 to 11, characterized in that: The battery body has an active material layer inside. On the connection path between the tab and the battery body, the distance between the fuse part and the active material layer is L. 12 mm, where 6.5 mm ≤ L 12 ≤21.5mm.

31. The battery pack according to any one of claims 1 to 11, characterized in that: The battery body has a tab glue inside, and the distance between the tab and the battery body is L. 13 mm, where 7 mm ≤ L 13 ≤22mm.

32. The battery pack according to any one of claims 1 to 11, characterized in that: The battery cell body has a diaphragm inside, and the distance between the fuse part and the diaphragm on the connection path between the tab and the battery cell body is L. 14 mm, where 5 mm ≤ L 14 ≤20mm.

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