Secondary battery

Abstract

The present invention relates to the technical field of batteries, and discloses a secondary battery, which comprises: a housing having a cavity; the battery cell is arranged in the cavity, and the battery cell comprises a battery cell body and a tab; the pole column is arranged on the shell; the adapter piece comprises a tab connecting part and a pole connecting part, and at least part of the tab is arranged opposite to the tab connecting part after the tab is led out of the battery cell body; and in the thickness direction of the battery cell, the thickness of the pole connecting part is L1, the thickness of the tab is D, in the thickness direction of the battery cell, the thickness of the battery cell is L, the width of the pole connecting part is L1, the width of the tab connecting part is L2, and (L1 / L2) * (D / (L-L2)) is 0.008-1. By controlling (L1 / L2) * (D / (L-L2)) to be within a range of 0.008-1, a space is reserved for a bending corner of the tab, so that the tab is prevented from being broken due to scratching of the shell, and even short circuit and insulation failure between the tab and the shell are avoided; and meanwhile, the over-current capability is considered, the balance of current transmission is realized, and excessive temperature rise of the battery is avoided.

Description

Technical Field

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

[0002] In secondary batteries, the adapter plate connecting the terminal post and the tab is an important component in battery manufacturing, and is usually also referred to as a pin, a connecting plate, or a conductive plate. Its function is to reliably connect the tab inside the battery cell to the external terminal post (positive or negative electrode), thereby achieving current conduction.

[0003] Currently, when the battery cell is inserted into the housing, the bent corner of the tab will rub against the housing, causing the tab to break when inserted into the housing, and even causing insulation failure between the battery cell and the housing, thereby triggering a short - circuit risk. Summary of the Invention

[0004] In view of this, the present invention provides a secondary battery to avoid the bent corner of the tab rubbing against the housing when the battery cell is inserted into the housing, which may cause the tab to break and even cause insulation failure between the battery cell and the housing, while taking into account the balance of battery current transmission.

[0005] The present invention provides a secondary battery, including: a housing having a cavity; a battery cell disposed in the cavity, the battery cell including a battery cell body and a tab; a terminal post disposed on the housing; an adapter plate including a tab connection portion and a terminal post connection portion, the tab connection portion being electrically connected to the tab, the terminal post connection portion being electrically connected to the terminal post, and at least a part of the tab is disposed opposite to the tab connection portion after being led out from the battery cell body; the thickness of the tab is D, in the thickness direction of the battery cell, the thickness of the battery cell is L, the width of the terminal post connection portion is L1, the width of the tab connection portion is L2, and (L1 / L2)×(D / (L - L2)) is 0.008 - 1, where the units of D, L, L1, and L2 are all mm.

[0006] Advantageous Effects: By controlling (L1 / L2)×(D / (L - L2)) within the range of 0.008 - 1, space is reserved for the bent corner of the tab to avoid the tab being broken due to rubbing against the housing, and even short - circuit and insulation failure between the tab and the housing; at the same time, the over - current capacity is taken into account, so that the over - current capacities of the tab connection portion and the terminal post connection portion are matched to ensure the over - current capacity of the adapter plate, thereby achieving the balance of current transmission and avoiding excessive battery temperature rise. 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 will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0008] Figure 1 is a perspective view of a secondary battery according to an embodiment of the present invention; Figure 2 is Figure 1 an exploded schematic view of the secondary battery shown; Figure 3 is Figure 2 a top view of the battery cell and the adapter plate shown; Figure 4 is Figure 2 a side view of the battery cell and the adapter plate shown; Figure 5 is Figure 4 a schematic structural view of the adapter plate shown; Figure 6 is a schematic structural view of an adapter plate of another secondary battery according to an embodiment of the present invention.

[0009] Explanation of reference numerals: 1. Housing; 101. Outer housing; 102. Cover plate; 2. Battery cell; 201. Battery cell body; 202. Tab; 2021. Welding area; 3. Terminal; 4. Adapter plate; 401. Tab connection part; 402. Terminal connection part; 403. Transition part. Detailed implementation manners

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0011] The following will describe the embodiments of the present invention in conjunction with Figures 1 to 6 ,

[0012] According to an embodiment of the present invention, a secondary battery is provided, comprising: a housing 1, an electrode assembly 2, a terminal 3, and a connecting piece 4. The housing 1 has a cavity; the electrode assembly 2 is disposed in the cavity, and the electrode assembly 2 includes an electrode body 201 and an electrode tab 202; the terminal 3 is disposed on the housing 1; the connecting piece 4 includes an electrode-tab connecting portion 401 and a terminal connecting portion 402. The electrode-tab connecting portion 401 is electrically connected to the electrode tab 202, and the terminal connecting portion 402 is electrically connected to the terminal 3. The electrode tab 202 is disposed opposite to the electrode-tab connecting portion 401 after extending from one end of the electrode body 201; the thickness of the electrode tab 202 is D, in the thickness direction of the electrode assembly 2, the thickness of the electrode assembly 2 is L, the width of the terminal connecting portion 402 is L1, and the width of the electrode-tab connecting portion 401 is L2. (L1 / L2)×(D / (L - L2)) is 0.008 - 1, where the units of D, L, L1, and L2 are all mm.

[0013] By controlling (L1 / L2)×(D / (L - L2)) within the range of 0.008 - 1, space is reserved at the bending corner of the electrode tab 202 to avoid scraping the housing 1, which may cause the electrode tab 202 to break, or even cause a short circuit between the electrode tab 202 and the housing 1, resulting in insulation failure; at the same time, the overcurrent capacity is considered, so that the overcurrent capacities between the electrode-tab connecting portion 401 and the terminal connecting portion 402 are matched to ensure the overcurrent capacity of the connecting piece 4, thereby achieving the balance of current transmission and avoiding excessive temperature rise of the battery.

[0014] Further, (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 within the range formed by any two of the above values.

[0015] Further, L-L2 refers to the gap between the side of the tab connection part 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 current-carrying capacity of the tab connection part 401 is relatively weaker than that of the terminal connection part 402. By controlling the range of L1 / L2, the current-carrying capacities of the tab connection part 401 and the terminal connection part 402 are matched, avoiding uneven current-carrying between the tab connection part 401 and the terminal connection part 402 and weak local current-carrying capacity, which causes a large temperature rise of the battery. 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 tab connection part 401 has a good current-carrying capacity. By controlling the range of L1 / L2, the current-carrying balance between the tab connection part 401 and the terminal connection part 402 is achieved, avoiding weak current-carrying capacity of the terminal connection part 402, resulting in mismatched current-carrying capacities of the tab connection part 401 and the terminal connection part 402. For example, the current-carrying capacity at the position of the terminal connection part 402 is poor and the temperature rise is large, causing an increase in the overall temperature rise of the battery. 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 prone to rubbing against the housing 1 at the bending corner. When the battery cell 2 is inserted into the housing, the bent part of the tab 202 is prone to rubbing against the housing 1. Further controlling L-L2 requires considering the matching relationship between the terminal connection part 402 and the tab connection part 401 at the same time.

[0016] As can be seen from the above: when (L1 / L2)×(D / (L-L2)) is too small, there is a mismatch in the current-carrying capacities of the tab connection part 401 and the terminal connection part 402, weak current-carrying at the local position, increased heat generation, and a large temperature rise of the battery; when (L1 / L2)×(D / (L-L2)) is too large, there is a high risk of rubbing between the battery cell 2 and the housing 1, an increased risk of tab breakage. In addition, when the battery cell 2 is inserted into the housing, there is an easy short-circuit problem between the tab 202 and the housing 1, which also causes a large temperature rise of the battery.

[0017] Therefore, controlling (L1 / L2)×(D / (L-L2)) within a suitable range reserves space for the bending corner of the tab 202 while being compatible with the current-carrying capacity, avoiding tab breakage, and matching the current-carrying capacities between the tab connection part 401 and the terminal connection part 402 to ensure the current-carrying capacity of the adapter piece 4, so as to achieve the balance of current transmission.

[0018] Preferably, (L1 / L2) × (D / (L - L2)) is 0.02 - 0.49. As an 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 formed by any two of the above values. By further controlling the formula (L1 / L2) × (D / (L - L2)) within the range of 0.02 - 0.49, the overcurrent balance can be further balanced and the ear breakage can be avoided.

[0019] It should be noted that during current transmission, from the battery cell body 201 to the ear connection part 401, the pole connection part 402, and then to the pole 3.

[0020] Specifically, L1 / L2 is 1.1 - 1.5, L - L2 is 3 mm - 25 mm, and D is 0.05 mm - 2.5 mm. Preferably, L1 / L2 is 1.2 - 1.3, L - L2 is 4 mm - 15 mm, and D is 0.2 mm - 1.8 mm.

[0021] By further controlling L1 / L2 within the range of 1.1 - 1.5, the current transmission balance between the ear connection part 401 and the pole connection part 402 of the adapter piece 4 is realized, thereby improving the overall overcurrent capacity of the battery and realizing the balance of current transmission; by further controlling L - L2 within 3 mm - 25 mm, the abrasion between the bending corner of the ear 202 and the housing 1 is further avoided to cause insulation failure; at the same time, the current balance is taken into account; by further controlling D within the range of 0.05 mm - 2.5 mm, the overcurrent is improved, and at the same time, the risk of abrasion between the housing and the ear and ear breakage is reduced.

[0022] 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 within the range formed by any two of the above values, and L - L2 is 3 mm, 3.4 mm, 4 mm, 4.7 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 10.5 mm, 11 mm, 12 mm, 13 mm, 14 mm, 14.8 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 24.8 mm, 25 mm or within the range formed by any two of the above values.

[0023] Further, L1 is 10 mm - 100 mm, L2 is 6 mm - 95 mm, and L is 10 mm - 100 mm.

[0024] 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 formed by 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 formed by 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, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 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 or within the range formed by any two of the above values; L 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 formed by any two of the above values.

[0025] Further, the housing 1 is arranged 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.

[0026] Further, the connecting piece 4 is electrically connected to the tab 202 and the terminal 3 to realize current transmission; the material of the connecting piece 4 can be aluminum, copper, etc.

[0027] Further, the terminal 3 serves as the current output end of the battery to connect to an external busbar, etc., to realize the series and parallel connection between batteries; the terminal 3 can include a positive terminal and a negative terminal; the material of the terminal can be aluminum, copper; copper-aluminum composite, etc.

[0028] Further, the tab 202 serves as the current output end inside the battery cell 2, and the tab 202 is used to be electrically connected to the terminal 3, etc. The tab 202 can be cut from a current collector or can be a separately formed metal part. It can be understood that the positive tab is electrically connected to the positive electrode plate in the battery cell 2, and the negative tab is electrically connected to the negative electrode plate in the battery cell 2.

[0029] Further, the battery cell 2 includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the negative electrode sheet, and the separator are laminated to form the battery cell 2. The positive electrode sheet includes a positive current collector and a positive active material layer, and the negative electrode sheet includes a negative current collector and a negative active material layer. There is no particular limitation on the positive current collector as long as it has conductivity and does not cause adverse chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc. can be used; the negative current collector can be made of copper, stainless steel, nickel, titanium, etc. In a specific embodiment, aluminum can be used for the positive electrode and copper can be used for the negative electrode. The positive active material layer includes a positive active material, and the positive active material includes nickel cobalt manganese ternary material, lithium iron phosphate material, lithium manganese iron phosphate material, etc.; the negative active material layer includes a negative active material, and the negative active material includes artificial graphite, natural graphite, silicon-based material, etc.

[0030] 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 portion 401 and the corresponding side of the terminal connection portion 402. At this time, L1 > L2. To provide necessary space for the extraction of the tab 202, it is convenient to extract the tab 202 from at least one side of the tab connection portion 401 and avoid rubbing between the tab 202 and the housing 1.

[0031] In one embodiment, as Figure 6 shown, there is a gap between one side of the tab connection portion 401 and the corresponding side of the terminal connection portion 402, and the other side of the tab connection portion 401 is aligned with the corresponding side of the terminal connection portion 402. L1 / L2 is 1.1 - 1.3. The tab connection portion 401 is disposed close to one side with respect to the terminal connection portion 402. For example, in Figure 6 , the tab connection portion 401 is disposed close to the left side with respect to the terminal connection portion 402. Since the tab 202 is disposed close to the right side after being extracted, the current transmission path of the left electrode sheet becomes longer during current transmission, which is likely to cause uneven overcurrent.

[0032] Therefore, by further controlling the setting of L1 / L2 within the range of 1.1 - 1.3, the overcurrent capabilities between the tab connection portion 401 and the terminal connection portion 402 are matched, ensuring the overcurrent capability of the adapter sheet 4 to achieve the balance of current transmission.

[0033] 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 composed of any two of the above values.

[0034] It should be noted that Figure 6 the left - right direction in Figure 6 refers to the thickness direction.

[0035] 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 part 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 - carrying between the tab 202 and the adapter piece 4 is achieved, improving the over - current capacity of the battery; meanwhile, a large welding area 2021 is avoided, preventing damage to the components around the adapter piece 4.

[0036] 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 composed of any two of the above values.

[0037] Specifically, L4 is 1 mm - 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 the range composed of any two of the above values.

[0038] Furthermore, the length of the tab 202 extending out is 8 mm - 60 mm. The length of the tab 202 extending out from the battery cell body 201 is the extension length of the tab 202. By further controlling the extension length within the range of 8 mm - 60 mm, the space occupied by the tab 202 in the housing 1 is reduced; meanwhile, the current - carrying area of the tab 202 is increased, improving the over - current capacity of the tab 202, and avoiding the problem of long over - current path and insufficient over - current area of the electrode tab on the side far from the tab.

[0039] Preferably, the extension length of the tab 202 is 8 mm, 9 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm or within the range composed of any two of the above values.

[0040] It should be noted that, along the extension direction of the tab 202, the distance between the side of the tab 202 close to the battery cell body 201 and the side of the tab 202 far from the battery cell body 201. Specifically, when measuring the extension length of the tab 202, a flexible ruler can be used to measure the distance between the section of the tab 202 close to the battery cell body 201 and the section far from the battery cell body 201 along the extension direction of the tab 202; or a line can be used. One end of the line overlaps with the connection end of the tab 202 and the battery cell body 201, and the other end of the line overlaps with the section of the tab far from the battery cell body, and then the length of the line is measured with a ruler.

[0041] In another embodiment, as 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 relative to 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 from both sides of the tab connection part 401 and then electrically connect to the adapter piece 4, the risk of rubbing between the two side tabs 202 and the housing 1 increases when the battery cell 2 is put into the housing; it is easy to cause the insulation failure of the battery cell 2 and trigger a short circuit. Therefore, by further controlling L1 / L2 within the range of 1.15 - 1.4, the rubbing between the tab 202 and the housing 1 is further reduced, the breakage of the tab is avoided, and the risk of battery insulation failure is reduced; at the same time, the current distribution is optimized, the current transmission impedance is reduced, and the current performance is improved.

[0042] 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 composed of any two of the above values.

[0043] Furthermore, the gap C is 1 mm - 3.5 mm. By further controlling the gap C within the range of 1 mm - 3.5 mm, space is reserved for the bending corner of the tab, the rubbing between the tab 202 and the housing 1 is further reduced, the breakage of the tab is avoided, and the risk of battery insulation failure is reduced.

[0044] 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 within the range composed of any two of the above values.

[0045] 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 part 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 piece 4 from both sides respectively. Here, L4 refers to the width of the welding area 2021 between the single-sided tab 202 and the tab connection part 401.

[0046] By further controlling the L4 / L2 within the range of 0.15 - 0.4, effective overcurrent between the tab 202 and the adapter 4 is achieved, 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. Additionally, since the tabs on both sides need to be welded to the adapter, controlling the L4 / L2 range can further prevent adjacent tabs from being damaged by welding heat during welding.

[0047] 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 composed of any two of the above values.

[0048] Specifically, the length of the tab 202 extending out is 5 mm - 50 mm. By further controlling the extension length within the range of 5 mm - 50 mm, the space occupied by the extended tab 202 in the housing 1 is reduced. At the same time, the overcurrent area of the tab 202 is increased, improving the overcurrent capacity of the tab and avoiding problems such as a long overcurrent path and insufficient overcurrent area of the electrode tab.

[0049] Preferably, the extension 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 the range composed of any two of the above values.

[0050] In one embodiment, as Figure 3 and Figure 5 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 overcurrent capacity of the terminal connection part 402 is improved. At the same time, it also prevents the width of the tab connection part 401 from being too large, which may easily cause a mismatch in overcurrent between the tab connection parts 401 in the future. By controlling L2 / L within the range of 0.5 - 0.8, the overcurrent capacity of the tab connection part 401 is improved, which is beneficial for matching the overcurrent capacity of the terminal connection part 402. At the same time, it can further reduce the risk of insulation failure caused by the tab 202 being scratched against the housing 1 during bending.

[0051] 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 formed by any two of the above values, and L2 / L is 0.5, 0.51, 0.52, 0.53, 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 within the range formed by any two of the above values.

[0052] In one embodiment, as Figure 3 and Figure 5 shown, the tab 202 includes a plurality of tab sheets along the thickness direction of the tab 202, the plurality of tab sheets are stacked together, the number of tab sheets is greater than or equal to 15 layers, and L - L2 is 3.5 mm - 28 mm.

[0053] 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 3.5 mm - 28 mm, the gap between the tab connection part 401 and the edge of the battery cell 2 is controlled within the range of 3.5 mm - 28 mm, further reducing the risk of rubbing between the tab 202 and the housing 1 and reducing the risk of the tab breaking.

[0054] Preferably, the number of tab sheets 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 within the range formed by any two of the above values.

[0055] In one embodiment, as Figure 3 and Figure 5As shown, the tab 202 extends to the surface of the tab connection part 401 facing away from the battery cell 2 after being led out, and L-L2 is 4 mm - 25 mm. When the tab 202 is folded to the surface of the tab connection part 401 facing away from the battery cell 2 and welded to the tab connection part 401, by controlling L-L2 within the range of 4 mm - 25 mm, the risk of excessive rubbing between the tab 202 after being bent and the housing 1 can be further reduced, and the risk of the tab breaking can be reduced; in addition, when the tab is bent to the surface of the adapter piece 4 away from the battery cell 2, the thickness space of the adapter piece can be borrowed to further reduce the space occupied by the tab bending in the housing.

[0056] It can be understood that in another embodiment, the tab 202 extends to the surface of the tab connection part 401 facing the battery cell 2 after being led out.

[0057] In one embodiment, the number of battery cells 2 is one or more. At this time, at least one battery cell 2 is arranged in the housing 1. When the number of battery cells 2 is multiple, by connecting the multiple battery cells 2 in series or in parallel, the total capacity and output voltage of the battery system can be significantly increased, and the number of battery cells 2 can be adjusted according to actual needs to meet application scenarios with different powers and energies.

[0058] In one embodiment, as Figure 3 and Figure 5 shown, the secondary battery includes multiple battery cells 2. The tabs 202 of the multiple battery cells 2 are respectively led out from both sides of the adapter piece 4 along the thickness direction of the battery cell 2, and L-L2 is 4 mm - 20 mm. The tabs 202 of the multiple battery cells 2 are respectively bent from both sides in the thickness direction of the tab connection part 401 to the surface of the tab connection part 401 and welded to the tab connection part 401. It is equivalent to first connecting the tabs 202 in parallel, and then collecting and electrically connecting to the adapter piece 4, reducing the resistance; by controlling L-L2 within the range of 4 mm - 20 mm, the risk of rubbing between the two-side tabs 202 after being bent and the housing 1 can be reduced.

[0059] Specifically, in Figure 2 , the number of battery cells 2 is two. The tab 202 of one battery cell 2 is led out from one side of the adapter piece 4 along the thickness direction of the battery cell 2, then bent to the surface of the tab connection part 401 away from 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 piece and then bent to the surface of the tab connection part 401 away from the battery cell 2 and welded to the tab connection part 401.

[0060] In one embodiment, the tab 202 extends from the length direction of the battery cell body 201. In the length direction of the battery cell body 201, the tab connection part 401 is spaced apart from the battery cell body 201, and the tab connection part 401 and the terminal connection part 402 form a certain angle, and the angle is 80°-110°. At this time, the adapter plate 4 is L-shaped, and the adapter plate 4 better adapts to the space limitation inside the battery, makes full use of the effective space for arrangement, and connects the tab 202 in one direction and the terminal 3 in another direction, simplifying the extraction path of the tab 202 and reducing the interference problem during the assembly process.

[0061] Preferably, the angle is 90°.

[0062] In one embodiment, as Figure 3 and Figure 5 shown, the tab 202 further includes a transition part 403 arranged between the tab connection part 401 and the terminal connection part 402. In the thickness direction of the battery cell 2, the width of the transition part 403 is L3, L2 < L3 < L1, and L3 is 8 mm - 98 mm. In the current transmission path, it passes through the tab connection part 401, the transition part 403 and the terminal connection part 402 in sequence. L2 < L3 < L1 makes the width of the adapter plate 4 decrease in sequence, avoiding the sudden change of the cross-sectional area of the adapter plate 4 resulting in a sharp increase or decrease in the local current density, thereby causing a mismatch in the overcurrent capacity, ensuring that the current is more evenly distributed on the entire adapter plate 4, and reducing the risk of local overcurrent.

[0063] 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 the range composed of any two of the above values.

[0064] 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 ensure that the current smoothly transitions from the transition part 403 to the terminal connection part 402, avoiding the sudden change of the cross-sectional area of the adapter plate 4 resulting in a sharp increase or decrease in the local current density, thereby causing a mismatch in the overcurrent capacity, and helping to improve the overcurrent capacity of the adapter plate; by further controlling L3 / L2 within the range of 1.1 - 1.3, it can ensure that the current smoothly transitions from the tab connection part 401 to the transition part 403, avoiding the sudden change of the cross-sectional area of the adapter plate 4 resulting in a sharp increase or decrease in the local current density, thereby causing a mismatch in the overcurrent capacity, and helping to improve the overcurrent capacity of the adapter plate.

[0065] Further, the housing 1 includes an outer housing 101 and a cover plate 102. There is a gap between the two side edges of the transition portion 403 and the edge of the battery cell 2, which facilitates 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.

[0066] In one embodiment, the thickness d of the tab is 0.002 mm - 0.015 mm. By controlling the thickness of the tab within the range of 0.002 mm - 0.015 mm, not only can the rubbing between the tab 202 and the housing 1 be avoided, improving the safety performance of the battery, but also the over-current capacity of the battery can be ensured, thereby enhancing the conductive capacity of the battery.

[0067] 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 composed of any two of the above values.

[0068] In one embodiment, the tab 202 has a welding portion, and the welding portion includes a first welding zone and a second welding zone. The first welding zone is the area where multiple layers of tabs are welded, and the second welding zone is the area where the tab 202 is welded to the tab connection portion 401.

[0069] If the multiple layers of tabs are directly welded to the adapter piece 4, the thickness of the multiple layers of tabs is relatively thick, and more welding energy is required to weld the multiple layers of tabs to the adapter piece 4, which may lead to uneven welding or over-welding, increasing the risk of poor welding or virtual welding of a single layer of tab; if the local temperature is too high, it may cause thermal damage to the separator or packaging material, increasing the risk of short circuit.

[0070] Therefore, first weld the multiple layers of tabs together, and then weld the tab 202 to the tab connection portion 401. Welding the multiple layers of tabs together can significantly improve the overall mechanical strength, reduce the risk of deformation or fracture caused by bending or vibration, and the possibility of poor welding. After welding the multiple layers of tabs, the total cross-sectional area increases and the resistance decreases, thereby improving the current distribution. After pre-welding the multiple layers of tabs into a whole, only one welding is required to complete the connection with the adapter piece 4, simplifying the assembly process.

[0071] Further, the multiple layers of tabs are welded together by ultrasonic welding. Ultrasonic welding can ensure that the contact surfaces between the multiple layers of tabs are fully fused to form a uniform connection. The tab 202 and the tab connection portion 401 are welded together by laser welding. The solder joints formed by laser welding have high strength and can withstand greater mechanical stress, making the connection strength between the tab 202 and the adapter piece 4 higher.

[0072] In one embodiment, the housing 1 includes an outer housing 101 and a cover plate 102. The outer housing 101 has a receiving cavity with at least one end open. The cover plate 102 is disposed at the opening, and the cover plate 102 is used to block the opening. The terminal post 3 is disposed on the cover plate 102.

[0073] Specifically, in the length direction of the battery cell body 201, the tabs 202 extend from the length direction of the battery cell body 201 respectively. In the height direction of the housing 1, one end of the housing 1 has an opening, the cover plate 102 is snapped onto the opening, the terminal post 3 is disposed on the cover plate 102, the adapter plate 4 is L-shaped, the tab connecting portion 401 and the side surface of the battery cell body 201 in the length direction are oppositely disposed, and the terminal post connecting portion 402 is electrically connected to the terminal post 3 on the cover plate 102.

[0074] Furthermore, the material of the cover plate 102 can be aluminum, aluminum alloy, steel, etc.; specifically, it can be aluminum-magnesium alloy, aluminum-manganese alloy, stainless steel, nickel-plated steel, carbon steel, etc.

[0075] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application. For those without specific experimental steps or conditions noted in the embodiments and comparative examples, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed.

[0076] The preparation process of the battery includes: (1) Preparation of the positive electrode sheet: Mix 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 in a mass ratio of 95:3:2, add the solvent NMP, and stir under the action of a vacuum mixer until the system becomes homogeneous to obtain a positive electrode slurry; uniformly coat the positive electrode slurry on both surfaces of the positive electrode current collector aluminum foil, dry it at room temperature and then transfer it to an oven for further drying, and then obtain the positive electrode sheet through cold pressing and slitting.

[0077] (2) Preparation of the negative electrode sheet: Mix the negative electrode active material graphite or a mixture of graphite and other active materials (such as silicon-based materials) obtained in different mass ratios, conductive agent acetylene black, thickening CMC, and binder SBR in a mass ratio of 96:1:1.5:1.5, add the solvent deionized water, and stir under the action of a vacuum mixer until the system becomes homogeneous to obtain a negative electrode slurry; uniformly coat the negative electrode slurry on both surfaces of the negative electrode current collector copper foil, dry it at room temperature and then transfer it to an oven for further drying, and then obtain the negative electrode sheet through cold pressing and slitting.

[0078] (3) Preparation of the electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, the thoroughly dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0079] (4) Preparation of the separator: A polyethylene film was selected as the separator.

[0080] (5) Preparation of the lithium-ion battery: The above positive electrode sheet, separator, and negative electrode sheet were prepared in sequence through the stacking process, with the separator placed between the positive and negative electrode sheets to play an insulating role. After preparing the battery cell 2, the battery cell 2 was put into the shell, the battery cover plate 102 was welded, and processes such as injecting electrolyte, forming, and constant volume were carried out on the battery.

[0081] In a specific embodiment of the present application, nickel-cobalt-manganese ternary was selected as the positive electrode, and the specific structure was LiNi 0.6 Co 0.2 Mn 0.2 O2; The negative electrode active material was selected as artificial graphite for illustration.

[0082] Among them, the temperature testing method of the battery cell 2 included loading the battery cell 2 into the housing 1, sealing and welding the cover plate 102 and the housing 1. A pole column 3 was provided on the cover plate 102, and a temperature rise test was carried out on the battery. The specific test steps were as follows: Constant current charging was carried out at a 3C rate to 4.25V, and constant voltage charging was carried out until the current dropped to 0.05C; A temperature sensor was connected to the pole column 3, and during the charging process, the temperature of the pole column 3 was sampled to obtain the highest temperature T in the area of the pole column 3. The test results are shown in Table 1 below.

[0083] Table 1 Battery parameters and performance

[0084] It can be seen from Examples 1 to 13, Comparative Example 1, and Comparative Example 2 in Table 1: When the range of the formula (L1 / L2) × (D / (L - L2)) satisfies 0.008 - 1, the temperature rise of the pole column is less than 60°C, and the battery has good overcurrent capacity; and the pole ear fracture rate is less than 10%.

[0085] In Examples 1 to 5, L1 / L2, D, L-L2, and (L1 / L2)×(D / (L-L2)) are all within the preferred ranges, that is, L1 / L2 is 1.2 - 1.3, D is 0.2 mm - 1.8 mm, L-L2 is 4 mm - 15 mm, (L1 / L2)×(D / (L-L2)) is 0.02 - 0.49, the temperature rise of the terminal post is less than or equal to 40 °C, the battery state is good, and none of the tabs are broken.

[0086] In Examples 6 to 8, L1 / L2 satisfies the range of 1.1 - 1.5, D satisfies the range of 0.05 mm - 2.5 mm, L-L2 satisfies the range of 3 mm - 25 mm, and the formula (L1 / L2)×(D / (L-L2)) is within the preferred range of 0.02 - 0.49. The temperature rise of the terminal post is greater than 40 °C and less than or equal to 45 °C, the battery state is good, and none of the tabs are broken.

[0087] 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 4 mm - 15 mm. Among them, in Example 9, D satisfies the range of 0.05 mm - 2.5 mm, the temperature rise of the terminal post is greater than 40 °C and less than or equal to 45 °C, the battery state is good, and slight breakage occurs in the tabs; in Example 10, D satisfies the preferred range of 0.2 mm - 1.8 mm, the temperature rise of the terminal post is greater than 45 °C and less than or equal to 50 °C, and the battery state is qualified.

[0088] 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 0.05 mm - 2.5 mm. Among them, in Example 11, L-L2 satisfies the range of 3 mm - 25 mm, the temperature rise of the terminal post is greater than 50 °C and less than or equal to 55 °C, the battery state is qualified, and slight breakage occurs in the tabs; in Example 12, L-L2 satisfies the preferred range of 4 mm - 15 mm, the temperature rise of the terminal is greater than 55 °C and less than or equal to 60 °C, the battery state is qualified, and none of the tabs are broken.

[0089] In Example 13, D does not satisfy the range of 0.05 mm - 2.5 mm, L-L2 does not satisfy the range of 3 mm - 25 mm, L1 / L2 does not satisfy the range of 1.1 - 1.5, the formula (L1 / L2)×(D / (L-L2)) satisfies the range of 0.008 - 1, the temperature rise of the terminal post is greater than 55 °C and less than or equal to 60 °C, the battery state is qualified, and the breakage rate of the tabs is less than 10%.

[0090] In Examples 14 and 15, L3 / L1 does not satisfy the range of 0.75 - 0.92, the temperature rise of the battery terminal post increases, showing an improvement compared to Example 1.

[0091] In Comparative Example 1, (L1 / L2)×(D / (L-L2)) does not satisfy the range of 0.008-1, D satisfies the range of 0.05 mm-2.5 mm, L-L2 satisfies the range of 3 mm-25 mm, L1 / L2 satisfies the range of 1.1-1.5, the temperature rise of the terminal post is greater than 65 °C, the tab shows serious fracture, the battery is unqualified and cannot be used normally; in Comparative Example 2, (L1 / L2)×(D / (L-L2)) does not satisfy the range of 0.008-1, D satisfies the range of 0.05 mm-2.5 mm, L1 / L2 satisfies the range of 1.1-1.5, L-L2 satisfies the range of 3 mm-25 mm, the temperature rise of the terminal post is greater than 75 °C. Although the tab does not fracture, the temperature rise of the terminal post is greater than 75 °C, and the heat generation of the battery is too large, resulting in the battery being unable to be used normally.

[0092] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A secondary battery, characterized in that, Comprising: A housing (1) having a cavity; A battery cell (2) disposed within the cavity, the battery cell (2) including a battery cell body (201) and tabs (202); A terminal post (3) disposed on the housing (1); A connecting piece (4) including a tab connecting portion (401) and a terminal post connecting portion (402), the tab connecting portion (401) being electrically connected to the tab (202), the terminal post connecting portion (402) being electrically connected to the terminal post (3), and at least a part of the tab (202) being disposed opposite to the tab connecting portion (401) after extending from the battery cell body (201); The thickness of the tab (202) is D, in the thickness direction of the battery cell (2), the thickness of the battery cell (2) is L, the width of the terminal post connecting portion (402) is L1, the width of the tab connecting portion (401) is L2, and (L1 / L2)×(D / (L - L2)) is 0.008 - 1, where the units of D, L, L1, and L2 are all mm.

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

49.

3. The secondary battery according to claim 1, characterized in that, L1 / L2 is 1.1 - 1.5; and / or, L - L2 is 3 mm - 25 mm; and / or, D is 0.05 mm - 2.5 mm.

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

5. The secondary battery according to claim 1, wherein In the thickness direction of the battery cell (2), there is a gap between at least one side of the tab connecting portion (401) and the corresponding side of the terminal post connecting portion (402).

6. The secondary battery according to claim 5, characterized in that, There is a gap between one side of the tab connecting portion (401) and the corresponding side of the terminal post connecting portion (402), and the other side of the tab connecting portion (401) is aligned with the corresponding side of the terminal post connecting portion (402), and L1 / L2 is 1.1 - 1.

3.

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

7.

8. The secondary battery according to claim 6, characterized in that, The length of the tab (202) extending out is 8 mm - 60 mm.

9. The secondary battery according to claim 5, wherein There are gaps between the two sides of the tab connecting portion (401) and the corresponding sides of the terminal post connecting portion (402), and L1 / L2 is 1.15 - 1.

4.

10. The secondary battery according to claim 9, wherein, The gap is 1 mm - 3.5 mm.

11. The secondary battery according to claim 9, characterized in that, In the thickness direction of the battery cell (2), the width of the welding area between the tab (202) and the tab connecting portion (401) is L4, and L4 / L2 is 0.15 - 0.

4.

12. The secondary battery according to claim 9, characterized in that, The length of the tab (202) extending out is 5 mm - 50 mm.

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

8.

14. The secondary battery according to claim 1, wherein The tab (202) includes a plurality of tab sheets in the thickness direction of the tab (202), the number of tab sheets is greater than or equal to 15 layers, and L - L2 is 3.5 mm - 28 mm.

15. The secondary battery according to claim 1, characterized in that, After the tab (202) is led out from the battery cell body (201), it extends to the surface of the tab connection part (401) facing away from the battery cell (2), and L-L2 is 4 mm - 25 mm.

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

17. The secondary battery according to claim 1, characterized in that, The tab (202) is led out from the length direction of the battery cell body (201). In the length direction of the battery cell body (201), the tab connection part (401) is arranged at an interval from the battery cell body (201), and the tab connection part (401) and the terminal connection part (402) form a certain included angle, and the included angle is 80° - 110°.

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

19. The secondary battery according to claim 18, characterized in that, 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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