secondary batteries

Abstract

The present invention relates to the field of battery technology and discloses a secondary battery comprising: a housing having a cavity; a battery cell disposed in the cavity, the battery cell comprising a battery cell body and a tab; a pole disposed in the housing; and a transition piece comprising a tab connection portion and a pole connection portion, wherein the tab is at least partially disposed opposite the tab connection portion after being extended from the battery cell body. The tab has a thickness D, and in the thickness direction of the battery cell, the thickness of the battery cell is L, the width of the pole connection portion is L1, the width of the tab connection portion is L2, and (L1 / L2)×(D / (L-L2)) is 0.008-1. By controlling (L1 / L2)×(D / (L-L2)) within the range of 0.008-1, space is reserved at the bending corners of the tab, thereby preventing the tab from being broken by rubbing against the housing, or even shorting between the tab and the housing, resulting in insulation failure. At the same time, the overcurrent capacity is taken into account, achieving balanced current transmission and preventing excessive temperature rise in the battery.

Description

Technical Field

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

[0002] In secondary batteries, the adapter connecting the pole and the tab is an important component in battery manufacturing. It is also commonly called a pin, connecting piece or conductive piece. Its function is to reliably connect the tab inside the battery cell with the external pole (positive or negative pole) to achieve current conduction.

[0003] Currently, when the battery cell is installed into the shell, the bent corners of the tab will scratch the shell, causing the tab to break when entering the shell, or even causing the insulation between the battery cell and the shell to fail, thereby causing the risk of short circuit. Summary of the Invention

[0004] In view of this, the present invention provides a secondary battery to prevent the bent corners of the tabs from scratching the shell when the battery cell is inserted into the shell, causing the tabs to break or even causing insulation failure between the battery cell and the shell, while taking into account the balance of battery current transmission.

[0005] The present invention provides a secondary battery, comprising: a shell having a cavity; a battery cell arranged in the cavity, the battery cell comprising a battery cell body and a pole lug; a pole lug arranged in the shell; a switching piece comprising a pole lug connecting portion and a pole lug connecting portion, the pole lug connecting portion being electrically connected to the pole lug, the pole lug connecting portion being electrically connected to the pole lug, and the pole lug being at least partially arranged opposite to the pole lug connecting portion after being led out of the battery cell body; the pole lug having a thickness of D, a thickness of L in the thickness direction of the battery cell, a width of L1 of the pole lug connecting portion, a width of L2 of the pole lug connecting portion, and (L1 / L2)×(D / (L-L2)) being 0.008-1, wherein the units of D, L, L1, and L2 are all mm.

[0006] Beneficial effect: By controlling (L1 / L2)×(D / (L-L2)) within the range of 0.008-1, space is reserved for the bending corners of the tab to avoid scratching the shell and causing the tab to break, or even short circuit between the tab and the shell, resulting in insulation failure; at the same time, taking into account the overcurrent capacity, the overcurrent capacity between the tab connection and the pole connection is matched to ensure the overcurrent capacity of the adapter, so as to achieve balanced current transmission and avoid excessive temperature rise of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0008] Figure 1 is a three-dimensional diagram of a secondary battery according to an embodiment of the present invention;

[0009] Figure 2 for Figure 1 An exploded schematic diagram of a secondary battery is shown;

[0010] Figure 3 for Figure 2 A top view of the battery cell and adapter shown;

[0011] Figure 4 for Figure 2 A side view of the battery cell and adapter is shown;

[0012] Figure 5 for Figure 4 The schematic structural diagram of the adapter shown;

[0013] Figure 6 The figure is a schematic structural diagram of another secondary battery adapter according to an embodiment of the present invention.

[0014] Description of reference numerals:

[0015] 1. Shell; 101. Outer shell; 102. Cover plate;

[0016] 2. Battery cell; 201. Battery cell body; 202. Tab; 2021. Welding area;

[0017] 3. Pole;

[0018] 4. Adapter; 401. Pole ear connection; 402. Pole connection; 403. Transition part. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0020] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0021] According to an embodiment of the present invention, a secondary battery is provided, comprising: a shell 1, a battery cell 2, a pole 3, and an adapter 4, wherein the shell 1 has a cavity; the battery cell 2 is arranged in the cavity, and the battery cell 2 includes a battery cell body 201 and a tab 202; the tab 3 is arranged in the shell 1; the adapter 4 includes a tab connection portion 401 and a pole connection portion 402, the tab connection portion 401 is electrically connected to the pole tab 202, and the pole connection portion 402 is electrically connected to the pole 3, and the pole tab 202 is led out from one end of the battery cell body 201 and arranged opposite to the pole connection portion 401; the thickness of the pole tab 202 is D, and in the thickness direction of the battery cell 2, the thickness of the battery cell 2 is L, the width of the pole connection portion 402 is L1, and the width of the tab connection portion 401 is L2, and (L1 / L2)×(D / (L-L2)) is 0.008-1, wherein the units of D, L, L1, and L2 are all mm.

[0022] By controlling (L1 / L2)×(D / (L-L2)) within the range of 0.008-1, space is reserved for the bending corners of the tab 202 to avoid scratching the shell 1 and causing the tab 202 to break, or even a short circuit between the tab 202 and the shell 1, resulting in insulation failure; at the same time, the overcurrent capacity is taken into account, so that the overcurrent capacity between the tab connection part 401 and the pole connection part 402 is matched to ensure the overcurrent capacity of the adapter 4, so as to achieve balanced current transmission and avoid excessive temperature rise of the battery.

[0023] Furthermore, (L1 / L2)×(D / (L-L2)) is 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.923, 0.988 or is within the range of any two of the above values.

[0024] Furthermore, L-L2 refers to the gap between the side of the tab connection 401 and the edge of the battery cell 2 in the thickness direction of the battery cell 2. If D / (L-L2) is small, there is a situation where L-L2 is too large or D is too small. When L-L2 is too large, the overcurrent capacity of the tab connection 401 is weaker than that of the post connection 402. By controlling the L1 / L2 range, the overcurrent capacity of the tab connection 401 and the post connection 402 is matched, avoiding the overcurrent imbalance between the tab connection 401 and the post connection 402, the local overcurrent capacity is weak, and the battery temperature rise is large; if D / (L-L2) is large, there is a situation where D is too large or (L-L2) is too small. When L-L2 is too small, the overcurrent of the tab connection 401 The capacity is good. By controlling the L1 / L2 range, the overcurrent balance between the tab connection part 401 and the pole connection part 402 is achieved, and the weak overcurrent capacity of the pole connection part 402 is avoided, resulting in mismatched overcurrent capacities of the tab connection part 401 and the pole connection part 402. For example, the overcurrent at the pole connection part 402 is poor, the temperature rise is large, and the overall temperature rise of the battery increases. In addition, when D is too large, if L-L2 is small, the gap between the tab connection part 401 and the edge of the battery cell 2 is small, and the tab 202 is easy to scratch the shell 1 at the bending corner. When the battery cell 2 is put into the shell, the bending part of the tab 202 is easy to scratch the shell 1. Further control of L-L2 and the matching relationship between the pole connection part 402 and the tab connection part 401 need to be taken into consideration.

[0025] From the above, it can be seen that: if (L1 / L2)×(D / (L-L2)) is too small, there will be a mismatch in the current capacity between the tab connection part 401 and the pole connection part 402, the current flow at local locations will be weak, the heat generation will increase, and the battery temperature will rise significantly; if (L1 / L2)×(D / (L-L2)) is too large, there will be a high risk of scratching between the battery cell 2 and the shell 1, and the risk of the tab breaking will increase. In addition, when the battery cell 2 is inserted into the shell, a short circuit is likely to occur between the tab 202 and the shell 1, which will also cause a large temperature rise in the battery.

[0026] Therefore, (L1 / L2)×(D / (L-L2)) is controlled within an appropriate range, and space is reserved at the bending corners of the tab 202 while being compatible with the overcurrent capacity to avoid the tab from breaking. The overcurrent capacity matching between the tab connection part 401 and the pole connection part 402 ensures the overcurrent capacity of the adapter 4 to achieve balanced current transmission.

[0027] Preferably, (L1 / L2)×(D / (L-L2)) is 0.02-0.49. For example, (L1 / L2)×(D / (L-L2)) is 0.02, 0.023, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.094, 0.1, 0.111, 0.119, 0.15, 0.165, 0 .2, 0.23, 0.25, 0.3, 0.35, 0.4, 0.486, 0.45, 0.46, 0.47, 0.48, 0.49 or within the range of any two of the above values, by further controlling the formula (L1 / L2)×(D / (L-L2)) within the range of 0.02-0.49, to further take into account the overcurrent balance and avoid the breakage of the tab.

[0028] It should be noted that when the current is transmitted, it flows from the cell body 201 to the tab connection portion 401 , the pole connection portion 402 , and then to the pole 3 .

[0029] Specifically, L1 / L2 is 1.1-1.5, L-L2 is 3mm-25mm, and D is 0.05mm-2.5mm. Preferably, L1 / L2 is 1.2-1.3, L-L2 is 4mm-15mm, and D is 0.2mm-1.8mm.

[0030] By further controlling L1 / L2 within the range of 1.1-1.5, the current transmission balance between the tab connection part 401 and the pole connection part 402 of the adapter 4 is achieved, thereby improving the overall overcurrent capacity of the battery and achieving the balance of current transmission; by further controlling L-L2 within 3mm-25mm, the bending corners of the tab 202 and the shell 1 can be further avoided to avoid scratches and insulation failure; at the same time, the current balance is taken into account; by further controlling D within the range of 0.05mm-2.5mm, the overcurrent is improved, and at the same time, the risk of scratches between the shell and the tab and the tab breakage is reduced.

[0031] Preferably, L1 / L2 is 1.1, 1.15, 1.18, 1.2, 1.25, 1.27, 1.28, 1.3, 1.35, 1.4, 1.45, 1.5 or is within the range formed by any two of the above values, and L-L2 is 3mm, 3.4mm, 4mm, 4.7mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 10.5mm, 11mm, 12mm, 13mm, 14mm, 14.8mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 24.8mm, 25mm or is within the range formed by any two of the above values.

[0032] Furthermore, L1 is 10mm-100mm, L2 is 6mm-95mm, and L is 10mm-100mm.

[0033] Specifically, L1 is 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, or within the range of any two of the above values; L2 is 6 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 95 mm, or within the range of any two of the above values; D is 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 100 mm, or within the range of any two of the above values; 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm or in the range formed by any two of the above values; L is 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm or in the range formed by any two of the above values.

[0034] Furthermore, the housing 1 is disposed on the outermost side of the battery cell 2 to protect the battery cell 2. The material of the housing 1 can be selected from, but not limited to, aluminum, steel, aluminum alloy, etc. Specifically, the material of the housing 1 can be aluminum-manganese alloy, aluminum-magnesium alloy, stainless steel, nickel-plated steel, carbon steel, titanium, etc.

[0035] Furthermore, the adapter plate 4 is electrically connected to the tab 202 and the pole 3 to achieve current transmission; the material of the adapter plate 4 can be aluminum, copper, etc.

[0036] Furthermore, the pole 3 serves as the current output end of the battery, and is used to connect to an external busbar, etc., to achieve series and parallel connection between batteries; the pole 3 can include a positive pole and a negative pole; the material of the pole can be aluminum, copper, copper-aluminum composite, etc.

[0037] Furthermore, the tab 202 serves as the current output terminal inside the battery cell 2 and is used to be electrically connected to the electrode 3, etc. The tab 202 can be cut from the current collector or can be a separately formed metal part. It is understood that the positive tab is electrically connected to the positive electrode sheet in the battery cell 2, and the negative tab is electrically connected to the negative electrode sheet in the battery cell 2.

[0038] Furthermore, the battery cell 2 includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is disposed between the positive and negative electrode sheets. The positive, negative, and separator sheets are stacked to form the battery cell 2. The positive electrode sheet includes a positive current collector and a positive active material layer, while the negative electrode sheet includes a negative current collector and a negative active material layer. The positive electrode current collector is not particularly limited, as long as it is conductive and does not cause adverse chemical changes in the battery. Materials such as stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver can be used. The negative electrode current collector can be made of copper, stainless steel, nickel, titanium, or the like. In specific embodiments, aluminum can be used for the positive electrode, and copper can be used for the negative electrode. The positive electrode active material layer includes a positive electrode active material, such as a nickel-cobalt-manganese ternary material, lithium iron phosphate, or lithium iron manganese phosphate. The negative electrode active material layer includes a negative electrode active material, such as artificial graphite, natural graphite, or a silicon-based material.

[0039] In one embodiment, in the thickness direction of the battery cell 2, there is a gap between at least one side of the tab connection part 401 and the corresponding side of the pole connection part 402. At this time, L1>L2, which provides necessary space for the lead-out of the tab 202, facilitates the lead-out of the tab 202 from at least one side of the tab connection part 401, and avoids the tab 202 from being scratched by the shell 1.

[0040] In one embodiment, Figure 6 As shown, there is a gap between one side of the tab connection part 401 and the side corresponding to the pole connection part 402, and the other side of the tab connection part 401 is aligned with the side corresponding to the pole connection part 402, and L1 / L2 is 1.1-1.3. The tab connection part 401 is arranged close to one side relative to the pole connection part 402, for example, Figure 6 In the figure, the tab connection part 401 is arranged close to the left side relative to the pole connection part 402. Since the tab 202 is arranged close to the right side after being led out, the current transmission path of the left pole piece becomes longer during current transmission, which easily causes uneven overcurrent.

[0041] Therefore, by further controlling L1 / L2 to be set within the range of 1.1-1.3, the overcurrent capacity between the tab connection portion 401 and the pole connection portion 402 is matched, ensuring the overcurrent capacity of the adapter 4 to achieve balanced current transmission.

[0042] Preferably, L1 / L2 is 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.3 or within the range formed by any two of the above values.

[0043] It should be noted that Figure 6 The left and right direction in the figure refers to the thickness direction.

[0044] Furthermore, in the thickness direction of the battery cell 2, the width of the weld region 2021 between the tab 202 and the tab connection portion 401 is L4, and L4 / L2 is 0.2-0.7. By further controlling L4 / L2 within the range of 0.2-0.7, effective current flow between the tab 202 and the adapter 4 is achieved, improving the battery's current capacity. At the same time, a larger weld region 2021 is avoided, which could damage components surrounding the adapter 4.

[0045] Preferably, L4 / L2 is 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 or within the range of any two of the above values.

[0046] Specifically, L4 is 1 mm to 60 mm. Preferably, L4 is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, or within a range formed by any two of the above values.

[0047] Furthermore, the length of the tab 202 extending from the cell body 201 is 8 mm to 60 mm. By further controlling the extension length of the tab 202 within the range of 8 mm to 60 mm, the space occupied by the tab 202 in the housing 1 is reduced. At the same time, the tab 202 has a larger flow area, improving the current carrying capacity of the tab 202 and avoiding the problem of a long flow path and insufficient flow area on the side of the tab that is particularly far away from the tab.

[0048] Preferably, the lead-out length of the tab 202 is 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, or within a range formed by any two of the above values.

[0049] It should be noted that, along the lead-out direction of the pole tab 202, the distance between the side of the pole tab 202 close to the battery cell body 201 and the side of the pole tab 202 away from the battery cell body 201, specifically, when measuring the lead-out length of the pole tab 202, you can use a soft ruler to measure the distance between a section of the pole tab 202 close to the battery cell body 201 and a section away from the battery cell body 201 along the lead-out direction of the pole tab 202; you can also use a wire or the like along the lead-out direction of the pole tab 202, one end of the wire overlaps with the connection end of the pole tab 202 and the battery cell body 201, and the other end of the wire overlaps with a section of the pole tab away from the battery cell body, and then use a ruler to measure the length of the wire or the like.

[0050] In another embodiment, Figures 3 to 5As shown, there is a gap C between the two side edges of the tab connection part 401 and the corresponding side edges of the pole connection part 402, and L1 / L2 is 1.15-1.4. The tab connection part 401 is arranged in the middle of the pole connection part 402. At this time, the tab 202 is divided into two parts and led out from both sides of the tab connection part 401, which can disperse the current path, optimize the current distribution, reduce the current transmission impedance, and improve the current performance. However, since it is necessary to bend the two sides of the tab connection part 401 and then electrically connect them to the adapter 4, the risk of the tabs 202 on both sides and the shell 1 being scratched when the battery cell 2 is put into the shell increases; it is easy to cause the insulation failure of the battery cell 2 and cause a short circuit. Therefore, by further controlling L1 / L2 within the range of 1.15-1.4, the scratches between the tab 202 and the shell 1 can be further reduced, the tab breakage can be avoided, and the risk of battery insulation failure can be reduced; at the same time, the current distribution can be optimized, the current transmission impedance can be reduced, and the current performance can be improved.

[0051] Preferably, L1 / L2 is 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.3, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.4 or within the range formed by any two of the above values.

[0052] Furthermore, the gap C is 1mm-3.5mm. By further controlling the gap C within the range of 1mm-3.5mm, space is reserved for the bending corners of the tabs, thereby further reducing the chance of scratches between the tabs 202 and the shell 1, avoiding tab breakage, and reducing the risk of battery insulation failure.

[0053] Preferably, the gap C is 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm or is within the range of any two of the above values.

[0054] Furthermore, in the thickness direction of the battery cell 2, the width of the welding area 2021 between the tab 202 and the tab connection portion 401 is L4, and L4 / L2 is 0.15-0.4. It should be noted that the tab 202 can be divided into two parts, and welded to the adapter 4 from both sides respectively. Here, L4 refers to the width of the welding area 2021 between the tab 202 and the tab connection portion 401 on one side.

[0055] By further controlling L4 / L2 within the range of 0.15-0.4, effective overcurrent is achieved between the tab 202 and the adapter 4, thereby improving the overcurrent capacity of the battery. At the same time, since there are gaps on both sides, the tab can be divided into two parts. In addition, since both tabs need to be welded to the adapter, controlling the L4 / L2 range can further avoid damage to adjacent tabs due to welding heat during welding.

[0056] Further preferably, L4 / L2 is 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.25, 0.3, 0.35, 0.4 or within the range of any two of the above values.

[0057] Specifically, the lead-out length of the tab 202 is 5 mm to 50 mm. By further controlling the lead-out length within the range of 5 mm to 50 mm, the space occupied by the lead-out tab 202 in the housing 1 is reduced; at the same time, the flow area of ​​the tab 202 is increased, improving the tab's flow capacity and avoiding the problem of a long flow path and insufficient flow area in the electrode.

[0058] Preferably, the lead length of the tab 202 is 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, or within a range formed by any two of the above values.

[0059] In one embodiment, Figure 3 and Figure 5 As shown, L1 / L is 0.75-0.95, and L2 / L is 0.5-0.8. By controlling L1 / L within the range of 0.75-0.95, the current capacity of the pole connection portion 402 is improved. This also prevents the tab connection portion 401 from being too wide, which could easily cause a mismatch in current flow between the tab connection portion 401 and the pole connection portion 402. By controlling L2 / L within the range of 0.5-0.8, the current capacity of the tab connection portion 401 is improved, which is conducive to matching the current capacity of the pole connection portion 402. This also further reduces the risk of insulation failure caused by bending of the tab 202 and scratching of the housing 1.

[0060] Preferably, L1 / L is 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95 or within the range of any two of the above values, and L2 / L is 0.5, 0.51, 0.52, 0.5 3. 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.7, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, or in the range formed by any two of the above values.

[0061] In one embodiment, Figure 3 and Figure 5 As shown, the tab 202 includes several layers of tab sheets along the thickness direction of the tab 202 , and the several layers of tab sheets are stacked together. The number of layers of tab sheets is greater than or equal to 15 layers, and L-L2 is 3.5mm-28mm.

[0062] By controlling the number of layers of the tab 202 to be greater than or equal to 15 layers, the current carrying capacity of the tab 202 is improved; at the same time, by controlling L-L2 within the range of 3.5mm-28mm, the gap between the tab connection part 401 and the edge of the battery cell 2 is controlled within the range of 3.5mm-28mm, thereby further reducing the risk of scratches between the tab 202 and the shell 1 and reducing the risk of the tab breaking.

[0063] Preferably, the number of layers of the tab sheet is 15, 16, 17, 18, 19, 20, 21, etc., and L-L2 is 3.5 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm or in the range of any two of the above values.

[0064] In one embodiment, Figure 3 and Figure 5As shown, the tab 202 is extended to the surface of the tab connection portion 401 facing away from the battery cell 2, and L-L2 is 4mm-25mm. The tab 202 is folded over to the surface of the tab connection portion 401 facing away from the battery cell 2 and welded to the tab connection portion 401. By controlling L-L2 within the range of 4mm-25mm, the tab 202 can be further reduced from scratching the housing 1 after being bent, thereby reducing the risk of the tab breaking. In addition, the tab is bent to the surface of the adapter plate 4 away from the battery cell 2, which can borrow the thickness of the adapter plate to further reduce the space occupied by the bent tab in the housing.

[0065] It is understandable that, in another embodiment, the tab 202 is led out and extends to the surface of the tab connection portion 401 facing the battery cell 2 .

[0066] In one embodiment, the number of battery cells 2 is one or more. In this case, at least one battery cell 2 is arranged in the shell 1. When the number of battery cells 2 is multiple, the total capacity and output voltage of the battery system can be significantly improved by connecting multiple battery cells 2 in series or in parallel. The number of battery cells 2 can be adjusted according to actual needs to meet application scenarios with different power and energy.

[0067] In one embodiment, Figure 3 and Figure 5 As shown, the secondary battery includes multiple cells 2, each of which has tabs 202 extending from a transfer plate 4 along the thickness of the cell 2, with L-L2 ranging from 4mm to 20mm. The tabs 202 of the multiple cells 2 are bent from opposite sides of the tab connection portion 401 along the thickness of the cell 2 to the surface of the tab connection portion 401 and then welded to the tab connection portion 401. This is equivalent to first connecting the tabs 202 in parallel and then connecting them to the transfer plate 4 for electrical connection, thereby reducing resistance. By controlling L-L2 within the range of 4mm to 20mm, the risk of the bent tabs 202 rubbing against the housing 1 is reduced.

[0068] Specifically, in Figure 2 In the embodiment, there are two battery cells 2. The tab 202 of one battery cell 2 is led out from one side of the adapter plate 4 along the thickness direction of the battery cell 2 and then bent to the tab connection part 401 away from the surface of the battery cell 2 and welded to the tab connection part 401. The tab 202 of the other battery cell 2 is led out from the other side of the adapter plate and then bent to the surface of the tab connection part 401 away from the surface of the battery cell 2 and welded to the tab connection part 401.

[0069] In one embodiment, the tab 202 extends longitudinally from the cell body 201. The tab connection portion 401 is spaced apart from the cell body 201 along the length of the cell body 201, and the tab connection portion 401 forms an angle of 80°-110° with the post connection portion 402. In this embodiment, the adapter plate 4 is L-shaped, which better adapts to the space constraints within the battery and fully utilizes the available space for arrangement. Furthermore, connecting the tab 202 in one direction and the post 3 in the other direction simplifies the tab 202 extension path and reduces interference issues during assembly.

[0070] Preferably, the angle is 90°.

[0071] In one embodiment, Figure 3 and Figure 5 As shown, the tab 202 also includes a transition portion 403 disposed between the tab connection portion 401 and the post connection portion 402. In the thickness direction of the battery cell 2, the width of the transition portion 403 is L3, L2<L3<L1, and L3 is 8mm-98mm. In the current transmission path, passing through the tab connection portion 401, the transition portion 403, and the post connection portion 402 in sequence, L2<L3<L1 causes the width of the adapter 4 to decrease successively. This prevents a sudden change in the cross-sectional area of ​​the adapter 4 from causing a sharp increase or decrease in local current density, thereby causing a mismatch in overcurrent capacity. This ensures a more uniform distribution of current across the entire adapter 4, reducing the risk of local overcurrent.

[0072] Preferably, L3 is 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 98 mm or within a range formed by any two of the above values.

[0073] Furthermore, L3 / L1 is greater than or equal to 0.75 and less than or equal to 0.92, and L3 / L2 is 1.1-1.3. By further controlling L3 / L1 within the range of 0.75-0.92, it can be ensured that the current smoothly transitions from the transition portion 403 to the pole connection portion 402, avoiding the sudden change in the cross-sectional area of ​​the adapter 4 causing a sharp increase or decrease in the local current density, thereby causing a mismatch in the overcurrent capacity, which helps to improve the overcurrent capacity of the adapter; by further controlling L3 / L2 within the range of 1.1-1.3, it can be ensured that the current smoothly transitions from the pole ear connection portion 401 to the transition portion 403, avoiding the sudden change in the cross-sectional area of ​​the adapter 4 causing a sharp increase or decrease in the local current density, thereby causing a mismatch in the overcurrent capacity, which helps to improve the overcurrent capacity of the adapter.

[0074] Furthermore, the housing 1 includes an outer shell 101 and a cover plate 102. A gap is provided between the two sides of the transition portion 403 and the edges of the battery cell 2 to facilitate the arrangement of the lower insulating member of the cover plate 102. The lower insulating member is used to achieve insulation between the housing 1 and the battery cell 2.

[0075] In one embodiment, the thickness d of the tab is 0.002 mm to 0.015 mm. By controlling the thickness of the tab within the range of 0.002 mm to 0.015 mm, not only can the tab 202 be prevented from scratching against the housing 1, thereby improving the safety of the battery, but the battery's current capacity can also be guaranteed, thereby improving the battery's conductivity.

[0076] Preferably, d is 0.002 mm, 0.003 mm, 0.004 mm, 0.005 mm, 0.006 mm, 0.007, 0.008 mm, 0.009 mm, 0.01 mm, 0.011 mm, 0.012 mm, 0.013 mm, 0.014 mm, 0.015 mm or within the range formed by any two of the above values.

[0077] In one embodiment, the tab 202 has a welding portion, which includes a first welding area and a second welding area. The first welding area is the area where the multiple tab sheets are welded, and the second welding area is the area where the tab 202 is welded to the tab connecting portion 401 .

[0078] If the multi-layer pole tabs are directly welded to the adapter plate 4, the thickness of the multi-layer pole tabs is thicker, and more welding energy is required to weld the multi-layer pole tabs to the adapter plate 4, which may cause uneven welding or over-welding, and increase the risk of single-layer pole tabs having loose welding or cold welding; if the local temperature is too high, it will cause thermal damage to the diaphragm or packaging material, increasing the risk of short circuit.

[0079] Therefore, the multiple layers of tabs are first welded together, and then the tabs 202 and tab connectors 401 are welded together. This welding of the multiple tabs significantly improves overall mechanical strength and reduces the risk of deformation or breakage due to bending or vibration, as well as the possibility of poor welding. After welding the multiple tabs together, the total cross-sectional area increases, the resistance decreases, and thus improves current distribution. After pre-welding the multiple tabs into a single unit, connection to the adapter 4 only requires a single welding operation, simplifying the assembly process.

[0080] Furthermore, the multiple layers of tabs are ultrasonically welded together, ensuring that the contact surfaces between the multiple tabs are fully fused, forming a uniform connection. The tab 202 and the tab connection portion 401 are laser welded together. Laser welding creates a strong weld point that can withstand significant mechanical stress, further strengthening the connection between the tab 202 and the adapter 4.

[0081] In one embodiment, the housing 1 includes an outer shell 101 and a cover plate 102 . The outer shell 101 has a receiving cavity with at least one end open. The cover plate 102 is disposed at the opening and is used to seal the opening. The pole 3 is disposed on the cover plate 102 .

[0082] Specifically, in the length direction of the battery cell body 201, the tabs 202 are respectively led out from the length direction of the battery cell body 201. In the height direction of the shell 1, one end of the shell 1 has an opening, and the cover 102 is snapped into the opening. The pole 3 is set on the cover 102, and the adapter 4 is L-shaped. The tab connection part 401 and the battery cell body 201 are arranged opposite to each other on the side surfaces in the length direction, and the pole connection part 402 is electrically connected to the pole 3 on the cover 102.

[0083] Furthermore, the material of the cover plate 102 may be aluminum, aluminum alloy, steel, etc.; specifically, it may be aluminum-magnesium alloy, aluminum-manganese alloy, stainless steel, nickel-plated steel, carbon steel, etc.

[0084] The present application is further described in detail below with reference to specific examples. These examples are not to be construed as limiting the scope of protection claimed in this application. Where specific experimental steps or conditions are not specified in the examples and comparative examples, the conventional experimental steps or conditions described in the literature in this field can be followed.

[0085] The battery preparation process includes:

[0086] (1) Preparation of positive electrode:

[0087] The prepared positive electrode active material (such as nickel-cobalt-manganese ternary, lithium iron phosphate, lithium manganese iron phosphate), conductive agent acetylene black, and binder PVDF are mixed in a mass ratio of 95:3:2, and solvent NMP is added. The mixture is stirred under the action of a vacuum mixer until the system becomes uniform to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on both surfaces of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying, and then cold pressed and cut to obtain a positive electrode sheet.

[0088] (2) Preparation of negative electrode sheet:

[0089] The negative electrode active material graphite or a mixture of graphite and other active materials (such as silicon-based materials) in different mass ratios, the conductive agent acetylene black, the thickener CMC, and the binder SBR are mixed in a mass ratio of 96:1:1.5:1.5, and deionized water is added as a solvent. The mixture is stirred under the action of a vacuum mixer until the system becomes uniform to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on both surfaces of the negative electrode current collector copper foil, dried at room temperature, and then transferred to an oven for further drying, and then cold pressed and cut to obtain a negative electrode sheet.

[0090] (3) Preparation of electrolyte:

[0091] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0092] (4) Preparation of diaphragm:

[0093] A polyethylene film was selected as the separator.

[0094] (5) Preparation of lithium-ion batteries:

[0095] The positive electrode sheet, separator, and negative electrode sheet are prepared in sequence through a lamination process, so that the separator is placed between the positive and negative electrode sheets to play an isolating role. After the battery cell 2 is prepared, the battery cell 2 is placed in a shell, and the battery cover 102 is welded. The battery is then subjected to processes such as liquid injection, formation, and constant capacity.

[0096] In the specific embodiment of the present application, the positive electrode is selected from nickel, cobalt and manganese, and the specific structure is LiNi 0.6 Co 0.2 Mn 0.2 O2; graphite is selected as an example of the negative electrode active material.

[0097] The temperature test method for the battery cell 2 includes installing the battery cell 2 into the housing 1, welding the cover 102 to the housing 1, and providing a terminal 3 on the cover 102. The battery is then subjected to a temperature rise test. The specific test steps are as follows: charging at a constant current rate of 3C to 4.25V, and then charging at a constant voltage until the current drops to 0.05C. A temperature sensor is connected to the terminal 3. During charging, the temperature of the terminal 3 is sampled to obtain the maximum temperature T in the terminal 3 area. The test results are shown in Table 1 below.

[0098] Table 1 Battery parameters and performance

[0099]

[0100] Combining Examples 1 to 13, Comparative Example 1 and Comparative Example 2 in Table 1, it can be seen that:

[0101] When the range of the formula (L1 / L2)×(D / (L-L2)) satisfies 0.008-1, the pole temperature rise is less than 60°C, the battery has good overcurrent capacity; and the tab rupture rate is less than 10%.

[0102] In Examples 1 to 5, L1 / L2, D, L-L2 and (L1 / L2)×(D / (L-L2)) are all within the preferred range, that is, L1 / L2 is 1.2-1.3, D is 0.2mm-1.8mm, L-L2 is 4mm-15mm, (L1 / L2)×(D / (L-L2)) is 0.02-0.49, the temperature rise of the pole is less than or equal to 40°C, the battery is in good condition, and the pole ears are not broken.

[0103] In Examples 6 to 8, L1 / L2 satisfies the range of 1.1-1.5, D satisfies the range of 0.05mm-2.5mm, L-L2 satisfies the range of 3mm-25mm, the formula (L1 / L2)×(D / (L-L2)) is within the preferred range of 0.02-0.49, the pole temperature rise is greater than 40°C and less than or equal to 45°C, the battery is in good condition, and none of the tabs are broken.

[0104] In Examples 9 and 10, the formula (L1 / L2)×(D / (L-L2)) satisfies the range of 0.008-1, L1 / L2 satisfies the preferred range of 1.2-1.3, and L-L2 satisfies the preferred range of 4mm-15mm. In Example 9, D satisfies the range of 0.05mm-2.5mm, the pole temperature rise is greater than 40°C and less than or equal to 45°C, the battery is in good condition, and the tab has a slight fracture; in Example 10, D satisfies the preferred range of 0.2mm-1.8mm, the pole temperature rise is greater than 45°C and less than or equal to 50°C, and the battery is in good condition.

[0105] In Examples 11 and 12, the formula (L1 / L2)×(D / (L-L2)) satisfies the preferred range of 0.008-1, L1 / L2 satisfies the range of 1.1-1.5, and D satisfies the range of 0.05mm-2.5mm. In Example 11, L-L2 satisfies the range of 3mm-25mm, the pole temperature rise is greater than 50°C and less than or equal to 55°C, the battery state is qualified, and the pole tab has a slight fracture; in Example 12, L-L2 satisfies the preferred range of 4mm-15mm, the pole temperature rise is greater than 55°C and less than or equal to 60°C, the battery state is qualified, and the pole tab has no fracture.

[0106] In Example 13, D does not meet the range of 0.05mm-2.5mm, L-L2 does not meet the range of 3mm-25mm, L1 / L2 does not meet the range of 1.1-1.5, the formula (L1 / L2)×(D / (L-L2)) meets the range of 0.008-1, the pole temperature rise is greater than 55°C and less than or equal to 60°C, the battery state is qualified, and the tab rupture rate is less than 10%.

[0107] In Example 14 and Example 15, L3 / L1 does not meet the range of 0.75-0.92, and the temperature rise of the battery pole increases, which is improved compared with Example 1.

[0108] In Comparative Example 1, (L1 / L2)×(D / (L-L2)) does not meet the range of 0.008-1, D meets the range of 0.05mm-2.5mm, L-L2 meets the range of 3mm-25mm, L1 / L2 meets the range of 1.1-1.5, the pole temperature rise is greater than 65°C, the pole ear is severely fractured, the battery is unqualified and cannot be used normally; in Comparative Example 2, (L1 / L2)×(D / (L-L2)) does not meet the range of 0.008-1, D meets the range of 0.05mm-2.5mm, L1 / L2 meets the range of 1.1-1.5, L-L2 meets the range of 3mm-25mm, and the pole temperature rise is greater than 75°C. Although the pole ear is not fractured, the pole temperature rise is greater than 75°C, the battery generates too much heat, and the battery cannot be used normally.

[0109] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A secondary battery, characterized in that: include: A housing (1) having a cavity; A battery cell (2) is arranged in the cavity, and the battery cell (2) comprises a battery cell body (201) and a tab (202); A pole (3) is provided on the housing (1); The adapter plate (4) comprises a tab connection portion (401) and a pole connection portion (402), wherein the tab connection portion (401) is electrically connected to the tab (202), and the pole connection portion (402) is electrically connected to the pole (3), and the tab (202) is at least partially arranged opposite to the tab connection portion (401) after being led out from the battery cell body (201); The thickness of the tab (202) is D, the thickness of the battery cell (2) in the thickness direction of the battery cell (2) is L, the width of the pole connecting portion (402) is L1, the width of the tab connecting portion (401) is L2, (L1 / L2)×(D / (L-L2)) is 0.008-1, wherein the units of D, L, L1, and L2 are all mm; L1 / L2 is 1.1-1.5; L-L2 is 3 mm-25 mm; and D is 0.05 mm-2.5 mm.

2. The secondary battery according to claim 1, wherein (L1 / L2)×(D / (L-L2)) is 0.02-0.

49.

3. The secondary battery according to claim 1, wherein L1 is 10mm-100mm, L2 is 6mm-95mm, D is 0.05mm-2.5mm, and L is 10mm-100mm.

4. The secondary battery according to claim 1, wherein In the thickness direction of the battery core (2), there is a gap between at least one side of the tab connection portion (401) and a corresponding side of the pole connection portion (402).

5. The secondary battery according to claim 4, wherein There is a gap between one side of the tab connection portion (401) and the side corresponding to the pole connection portion (402), and the other side of the tab connection portion (401) is aligned with the side corresponding to the pole connection portion (402), with L1 / L2 being 1.1-1.

3.

6. The secondary battery according to claim 5, characterized in that In the thickness direction of the battery core (2), the width of the welding area between the tab (202) and the tab connection portion (401) is L4, and L4 / L2 is 0.2-0.

7.

7. The secondary battery according to claim 5, characterized in that The lead-out length of the tab (202) is 8 mm to 60 mm.

8. The secondary battery according to claim 4, wherein There is a gap between the two side edges of the pole lug connection portion (401) and the corresponding side edges of the pole connection portion (402), and L1 / L2 is 1.15-1.

4.

9. The secondary battery according to claim 8, characterized in that The gap is 1mm-3.5mm.

10. The secondary battery according to claim 8, wherein In the thickness direction of the battery core (2), the width of the welding area between the tab (202) and the tab connection portion (401) is L4, and L4 / L2 is 0.15-0.

4.

11. The secondary battery according to claim 8, wherein The lead-out length of the tab (202) is 5 mm to 50 mm.

12. The secondary battery according to claim 1, wherein L1 / L is 0.75-0.95, L2 / L is 0.5-0.

8.

13. The secondary battery according to claim 1, wherein The tab (202) comprises a plurality of tab sheets along a thickness direction of the tab (202), the number of the tab sheets being greater than or equal to 15, and L-L2 being 3.5 mm to 28 mm.

14. The secondary battery according to claim 1, wherein The tab (202) is led out from the battery cell body (201) and extends to the surface of the tab connection portion (401) facing away from the battery cell (2), with L-L2 being 4 mm to 25 mm.

15. The secondary battery according to claim 1, wherein The secondary battery comprises a plurality of battery cells (2), wherein the tabs (202) of the plurality of battery cells (2) are respectively led out from the adapter plate (4) along both sides of the thickness direction of the battery cells (2), and L-L2 is 4 mm-20 mm.

16. The secondary battery according to claim 1, wherein The tab (202) is extended from the length direction of the battery cell body (201). In the length direction of the battery cell body (201), the tab connection portion (401) is spaced apart from the battery cell body (201). The tab connection portion (401) and the pole connection portion (402) form a certain angle, which is 80°-110°.

17. The secondary battery according to any one of claims 1 to 16, characterized in that: The tab (202) further includes a transition portion (403) provided between the tab connection portion (401) and the pole connection portion (402); in the thickness direction of the battery cell (2), the width of the transition portion (403) is L3, L2<L3<L1, and L3 is 8 mm-98 mm.

18. The secondary battery according to claim 17, wherein: L3 / L1 is greater than or equal to 0.75 and less than or equal to 0.92, and L3 / L2 is 1.1-1.3.

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