A lithium-ion battery with two-sided pole columns and an assembly method

Abstract

The present invention discloses a lithium-ion battery with two-sided pole columns, which includes a first pole group and a second pole group; the first pole group and the second pole group form a pole group main body; the negative electrode tabs of the two pole groups are simultaneously welded to a negative electrode side cover plate; on one side surface of the positive electrode side, a matching inlaid battery cover plate is welded with a positive electrode lead piece; the positive electrode lead piece is respectively welded to the positive electrode tabs of the two pole groups; between the positive electrode side matching inlaid battery cover plate and the pole group main body and between the negative electrode side cover plate and the pole group main body, they are respectively clamped with an upper gasket bracket; the outer wall of the pole group main body is wrapped with a protective film; the pole group main body is installed in a battery case; a positive electrode cover plate flat is welded on the outside of one end of the battery case; the four peripheral edges of the negative electrode side cover plate are welded to the other end of the battery case. The present invention also discloses an assembly method for the lithium-ion battery with two-sided pole columns. The present invention can avoid the excessive length of the pole tabs, effectively reduce the waste of pole tab foil materials, and at the same time effectively avoid the loss of space utilization rate of the battery in the height direction.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a lithium-ion battery with two-sided pole columns and an assembly method thereof. Background Art

[0002] In recent years, as a green new energy source, lithium-ion batteries have been widely used in the power industry, consumer electronics industry, etc. Especially in the power transportation industry, the cruising range of electric vehicles has become the key to the industry development and competition, which puts higher requirements on the energy density of lithium-ion batteries. At present, the volume of power batteries is developing in the direction of getting larger, and the improvement of space utilization rate has become the key to the development of battery structure.

[0003] At present, most power batteries adopt a multi-layer cut tab winding or stacked butterfly welding assembly structure. After the multi-layer tabs are eccentrically (or centered) laminated and welded, they need to be connected to the inner side of the cover plate pole column. Therefore, it is necessary to retain a relatively long tab to ensure the current-carrying capacity and assemblability after the multi-layer tabs are laminated and welded. At the same time, as the battery thickness increases, the thickness of the welded single pole group increases, and the length of the tab will also increase accordingly. In this case, on the one hand, during the laser cutting (die cutting), stacking (or winding) process of the overly long tab, the tab is prone to collapse, fold, and breakage, and it is not easy to be detected by a CCD appearance inspection device or other means; on the other hand, it will also cause a large amount of tab foil waste.

[0004] To solve the above problems, a structure of adding a connecting piece for bending has emerged in the current industry. However, such a design will cause a loss of space utilization rate in the height direction of the battery.

[0005] Therefore, there is an urgent need to develop a technology at present that can avoid the overly long tab length, effectively reduce the waste of tab foil, and at the same time effectively avoid the loss of space utilization rate in the height direction of the battery. Summary of the Invention

[0006] The purpose of the present invention is to provide a lithium-ion battery with two-sided pole columns and an assembly method thereof in view of the technical defects existing in the prior art.

[0007] To this end, the present invention provides a lithium-ion battery with two-sided pole columns, including a first pole group, a second pole group, a negative electrode side cover plate, and a positive electrode side matching inlaid battery cover plate;

[0008] The first pole group and the second pole group are juxtaposed and stacked together to form a pole group main body;

[0009] On both sides of the first pole group, a first positive electrode tab and a first negative electrode tab are respectively arranged;

[0010] On both sides of the second pole group, a second positive electrode tab and a second negative electrode tab are respectively arranged;

[0011] The first positive electrode tab and the first negative electrode tab, as well as the second positive electrode tab and the second negative electrode tab, are all multi-layer electrode tabs.

[0012] The first negative electrode tab of the first electrode group and the second electrode group are connected to the negative electrode side cover plate. Specifically, any one of the following two connection structures is adopted:

[0013] The first connection structure is that the first negative electrode tab of the first electrode group and the second negative electrode tab of the second electrode group are directly welded to a negative electrode side cover plate at the same time.

[0014] The second connection structure is that the first negative electrode tab of the first electrode group and the second negative electrode tab of the second electrode group are ultrasonically welded to a negative electrode lead piece, and the negative electrode lead piece is laser welded to the negative electrode side cover plate.

[0015] A negative electrode post is provided at the center position of the negative electrode side cover plate.

[0016] A positive electrode lead piece is welded to one side surface of the positive electrode side matching inlaid battery cover plate.

[0017] The center position of the other side surface of the positive electrode side matching inlaid battery cover plate is welded to a positive electrode post.

[0018] Two positive electrode connection parts are provided on the positive electrode lead piece.

[0019] The two positive electrode connection parts are respectively welded to the first positive electrode tab of the first electrode group and the second positive electrode tab of the second electrode group.

[0020] The positions between the positive electrode side matching inlaid battery cover plate and the electrode group main body, and the positions between the negative electrode side cover plate and the electrode group main body are respectively clamped with an upper gasket bracket.

[0021] The outer wall of the electrode group main body is wrapped with a protective film.

[0022] The electrode group main body wrapped with the protective film is placed into a battery case with both ends open and hollow.

[0023] Both ends of the battery case are respectively clamped with an upper gasket bracket.

[0024] A positive electrode cover plate flat is welded to the outside of one end of the battery case close to the positive electrode side matching inlaid battery cover plate.

[0025] The four peripheral edges of the negative electrode side cover plate are welded to the four peripheral edges of the other end of the battery case.

[0026] Preferably, the first positive electrode tab of the first electrode group and the second positive electrode tab of the second electrode group connected by the two positive electrode connection parts are cross-connected together through a cross-bending operation.

[0027] Preferably, the two positive electrode connection parts are respectively ultrasonically welded or laser welded to the first positive electrode tab of the first electrode group and the second positive electrode tab of the second electrode group.

[0028] Preferably, the edges of the first positive electrode tab and the first negative electrode tab of the first electrode group do not exceed the center position of the tab setting surface of the first electrode group and are biased towards the upper side or the lower side of the first electrode group;

[0029] The second positive electrode tab and the second negative electrode tab of the second electrode group do not exceed the center position of the tab setting surface of the second electrode group and are biased towards the upper side or the lower side of the second electrode group.

[0030] Preferably, the first positive electrode tab and the first negative electrode tab of the first electrode group, and the second positive electrode tab and the second negative electrode tab of the second electrode group all use the ultrasonic welding method.

[0031] Preferably, the positive electrode side is equipped with an inlaid battery cover plate, which includes an outer pole post lead plate, an insulating washer, a cover plate main board, and a battery internal welding lead plate that are sequentially stacked from outside to inside;

[0032] The positive electrode post in the middle of the battery internal welding lead plate sequentially passes through the central through hole of the cover plate main board and the central through hole of the insulating washer, and then is inserted into the central through hole of the outer pole post lead plate;

[0033] On the outer pole post lead plate, two traction posts are arranged at intervals.

[0034] In addition, the present invention also provides an assembly method for the two-side pole post lithium-ion battery as described above, which specifically includes the following steps:

[0035] Step 1: Pre-weld the first positive electrode tab and the first negative electrode tab on both sides of the first electrode group, and pre-weld the second positive electrode tab and the second negative electrode tab on both sides of the second electrode group;

[0036] Step 2: Weld the first negative electrode tab of the pre-welded first electrode group and the second negative electrode tab of the second electrode group to the same negative electrode side cover plate;

[0037] Step 3: After the negative electrode tabs of the first electrode group and the second electrode group are welded, bend the first electrode group and the second electrode group by 90 degrees, that is, fold them in half with each other, so that the first electrode group and the second electrode group are combined together, complete the core encapsulation with glue, and then bend the negative electrode tabs of the first electrode group and the second electrode group towards the direction of the electrode group;

[0038] Step 4: Weld the positive electrode side inlaid battery cover plate to the positive electrode lead piece;

[0039] Step 5: Weld the positive electrode lead piece to the positive electrode tabs of the first electrode group and the second electrode group;

[0040] Step 6: Cross-connect the first positive electrode tab of the first electrode group and the second positive electrode tab of the second electrode group through a cross-bending operation.

[0041] Step 7: Install the upper gasket brackets of the two finished products in a snap-fastening manner at the positions between the positive electrode side mating inlaid battery cover plate and the electrode group main body, and between the negative electrode side cover plate and the electrode group main body, and then wrap a protective film on the outer wall of the electrode group main body; wherein, the first electrode group and the second electrode group are juxtaposed and stacked together to form the electrode group main body.

[0042] Step 8: Insert the electrode group main body after film wrapping into the barrel-shaped battery case. The specific operation is as follows: First, insert the positive electrode side into the battery case. When the positive electrode side mating inlaid battery cover plate passes through the battery case and reaches the designated position, perform a gravitational traction on the two traction posts on the positive electrode side mating inlaid battery cover plate, so that the positive electrode side mating inlaid battery cover plate is cooperatively connected with the positive electrode cover plate flat plate.

[0043] Step 9: Weld the four peripheral edges of the positive electrode cover plate flat plate on the outer side of one end of the battery case close to the positive electrode side mating inlaid battery cover plate. At the same time, weld the four peripheral edges of the other end of the battery case to the four peripheral edges of the negative electrode side cover plate to obtain a lithium-ion battery with two-sided pole columns.

[0044] Step 10: After completing the welding of the positive electrode cover plate flat plate and the positive electrode side mating inlaid battery cover plate, cut off the two traction posts on the positive electrode side mating inlaid battery cover plate by shearing.

[0045] Preferably, in Step 2, the first negative electrode tab of the first electrode group and the second negative electrode tab of the second electrode group are ultrasonically welded to a negative electrode lead piece, and the negative electrode lead piece is laser welded to the negative electrode side cover plate.

[0046] As can be seen from the technical solutions provided by the present invention above, compared with the prior art, the present invention provides a lithium-ion battery with two-sided pole columns and an assembly method, which is scientifically designed, can avoid the excessive length of the electrode tabs, effectively reduce the waste of electrode tab foil materials, and at the same time, effectively avoid the loss of space utilization rate in the height direction of the battery, and has great practical significance. Brief Description of the Drawings

[0047] Figure 1 It is a schematic structural diagram of the first electrode group in a lithium-ion battery with two-sided pole columns provided by the present invention; the shape and structure of the second electrode group are the same as those of the first electrode group.

[0048] Figure 2 It is a schematic structural diagram of a positive electrode lead piece in a lithium-ion battery with two-sided pole columns provided by the present invention. <L

[0049] Figure 3In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the welding state of the negative electrode tabs of the first electrode group and the second electrode group with a negative electrode side cover plate;

[0050] Figure 4 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the structure after the negative electrode tabs of the first electrode group and the second electrode group are bent relative to each other;

[0051] Figure 5 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the welding state of the positive electrode side matching inlaid battery cover plate and the positive electrode lead piece;

[0052] Figure 6 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the welding state of the positive electrode tabs of the first electrode group and the second electrode group with the positive electrode side matching inlaid battery cover plate;

[0053] Figure 7 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the state when the positive electrode tabs of the first electrode group and the second electrode group are bent after being welded to the positive electrode side matching inlaid battery cover plate Figure 1 ;

[0054] Figure 8 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the structure when the outer wall of the electrode group main body including the first electrode group and the second electrode group is wrapped with a protective film;

[0055] Figure 9 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the state of the electrode group main body when it is put into the shell;

[0056] Figure 10 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the battery appearance after the welding operation of the positive electrode cover plate flat is completed;

[0057] Figure 11 In a lithium-ion battery with two-sided pole columns provided by the present invention, a schematic diagram of the negative electrode side cover plate;

[0058] Figure 12 A three-dimensional structure schematic diagram of the positive electrode side matching inlaid battery cover plate in a lithium-ion battery with two-sided pole columns provided by the present invention;

[0059] Figure 13 A disassembled structure schematic diagram of the positive electrode side matching inlaid battery cover plate in a lithium-ion battery with two-sided pole columns provided by the present invention;

[0060] Figure 14 In a lithium-ion battery with two-sided pole columns provided by the present invention, an appearance schematic diagram of the positive electrode cover plate flat. Detailed implementation mode

[0061] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0062] See Figures 1 to 14 , the present invention provides a lithium-ion battery with two-sided pole columns, which is a blade-shaped square lithium-ion battery, specifically including a first pole group 1, a second pole group 2, a negative electrode side cover plate 3, and a positive electrode side matching inlaid battery cover plate 4;

[0063] The first pole group 1 and the second pole group 2 are juxtaposed and stacked on top of each other to form a pole group main body;

[0064] On both sides of the first pole group 1, a first positive electrode tab 101 and a first negative electrode tab 102 are respectively provided;

[0065] On both sides of the second pole group 2, a second positive electrode tab 201 and a second negative electrode tab 202 are respectively provided;

[0066] The first positive electrode tab 101 and the first negative electrode tab 102, as well as the second positive electrode tab 201 and the second negative electrode tab 202, are all multi-layer pole tabs;

[0067] The first negative electrode tab 102 of the first pole group 1 and the second pole group 2 are connected to the negative electrode side cover plate 3, and the specific connection structure adopts any one of the following two:

[0068] The first connection structure is: the first negative electrode tab 102 of the first pole group 1 and the second negative electrode tab 202 of the second pole group 2 are simultaneously directly welded to a negative electrode side cover plate 3 (specifically using the laser welding method of offset butterfly welding);

[0069] The second connection structure is: the first negative electrode tab 102 of the first pole group 1 and the second negative electrode tab 202 of the second pole group 2 are welded to a negative electrode lead piece (such as ultrasonic welding), and the negative electrode lead piece is welded to the negative electrode side cover plate 3 (such as laser welding).

[0070] At the center position of the negative electrode side cover plate 3, a negative electrode column 30 is provided;

[0071] On one side surface of the positive electrode side matching inlaid battery cover plate 4, a positive electrode lead piece 5 is welded (such as laser welding);

[0072] At the center position of the other side surface of the positive electrode side matching inlaid battery cover plate 4, it is welded to a positive electrode column 440;

[0073] Two positive electrode connection parts 50 are provided on the positive electrode lead piece 5;

[0074] Two positive electrode connection parts 50 are respectively welded (such as by ultrasonic welding or laser welding) to the first positive electrode tab 101 of the first electrode group 1 and the second positive electrode tab 201 of the second electrode group 2;

[0075] The positions between the positive electrode side mating inlaid battery cover plate 4 and the electrode group body, and between the negative electrode side cover plate 3 and the electrode group body are respectively snap-connected to an upper gasket bracket 6;

[0076] The outer wall of the electrode group body is wrapped with a protective film;

[0077] The electrode group body wrapped with the protective film is placed into a battery case 7 with openings at both ends and hollow inside;

[0078] Both ends of the battery case 7 are respectively snap-connected to an upper gasket bracket 6;

[0079] It should be noted that the upper gasket bracket 6 is made of plastic and is placed into the case 7 to protect the electrode tabs;

[0080] On the outside of one end of the battery case 7 close to the positive electrode side mating inlaid battery cover plate 4, a positive electrode cover plate flat 8 is welded;

[0081] The four peripheral edges of the negative electrode side cover plate 3 are welded to the four peripheral edges of the other end of the battery case 7.

[0082] In the present invention, specifically, the first positive electrode tab 101 of the first electrode group 1 and the second positive electrode tab 201 of the second electrode group 2 connected by the two positive electrode connection parts 5 are cross-connected together through a cross-bending operation.

[0083] In the present invention, specifically, the first electrode group 1 and the second electrode group 2 adopt a stacked structure.

[0084] In the present invention, specifically, the edges of the first positive electrode tab 101 and the first negative electrode tab 102 of the first electrode group 1 do not exceed the center position of the electrode tab setting surface of the first electrode group 1 and are biased towards the upper side or the lower side of the first electrode group 1;

[0085] The second positive electrode tab 201 and the second negative electrode tab 202 of the second electrode group 2 do not exceed the center position of the electrode tab setting surface of the second electrode group 2 and are biased towards the upper side or the lower side of the second electrode group 2.

[0086] In the present invention, specifically, the first positive electrode tab 101 and the first negative electrode tab 102 of the first electrode group 1, and the second positive electrode tab 201 and the second negative electrode tab 202 of the second electrode group 2 are all directly pre-welded to the electrode tabs by ultrasonic welding to fix the welding positions of the electrode tabs.

[0087] In the present invention, refer to Figure 13As shown in the figure, the positive electrode side is equipped with an inlaid battery cover plate 4, which includes an outer pole post lead plate 41, an insulating washer 42, a cover plate main board 43, and a battery internal welding lead plate 44 that are sequentially stacked from outside to inside;

[0088] The positive electrode post 440 in the middle of the battery internal welding lead plate 44 sequentially passes through the central through hole of the cover plate main board 43 and the central through hole of the insulating washer 42, and then is inserted into the central through hole of the outer pole post lead plate 41;

[0089] On the outer pole post lead plate 41, two traction posts 40 are arranged at intervals;

[0090] It should be noted that the traction post 40 is used to traction the positive electrode side inlaid battery cover plate 4 during the assembly process, so that the positive electrode side inlaid battery cover plate 4 can be assembled at the specified assembly position.

[0091] The outer pole post lead plate 41, as the external lead piece of the battery pole post, is the power export carrier during the use of the battery and the welding plane for subsequent assembly.

[0092] The insulating washer 42 is used for insulation between the positive electrode post 440 and the positive electrode cover plate flat 8, so that the battery case 7 is not charged;

[0093] The cover plate main board 43 is the carrier for supporting the positive electrode post 440, and it is welded to the positive electrode cover plate flat 8;

[0094] The battery internal welding lead plate 44 is used to weld the positive electrode lead piece 5 and is connected to the positive electrode tab.

[0095] It should be noted that for the positive electrode side inlaid battery cover plate 4 of the present invention, it can well export the power of the battery, insulate between the battery case and the pole post, ensure the safety of the battery, facilitate welding, save the internal structure of the battery, and conveniently complete the assembly and welding.

[0096] For the present invention, in order to assemble the aforementioned blade square lithium-ion battery, the present invention also provides an assembly method for the blade square lithium-ion battery, which specifically includes the following steps:

[0097] Step 1, as shown in Figure 1 the figure, pre-weld the first positive electrode tab 101 and the first negative electrode tab 102 on both sides of the first pole group 1, and pre-weld the second positive electrode tab 201 and the second negative electrode tab 202 on both sides of the second pole group 2; specifically, ultrasonic welding can be used;

[0098] Step 2, as shown in Figure 3As shown, the first negative electrode tab 102 of the first electrode group 1 and the second negative electrode tab 202 of the second electrode group 2 after pre-welding are welded to the same negative electrode side cover plate 3. Specifically: on the negative electrode tab sides of the first electrode group 1 and the second electrode group 2, they are directly welded to the negative electrode side cover plate 3 by means of butterfly laser welding;

[0099] In step 2, the first negative electrode tab 102 of the first electrode group 1 and the second negative electrode tab 202 of the second electrode group 2 are ultrasonically welded to a negative electrode lead piece, and the negative electrode lead piece is laser welded to the negative electrode side cover plate 3.

[0100] Step 3, refer to Figure 4 As shown, after the negative electrode tabs of the first electrode group 1 and the second electrode group 2 are welded, the first electrode group 1 and the second electrode group 2 are bent 90 degrees, that is, folded against each other, so that the first electrode group 1 and the second electrode group 2 are combined together, and the core wrapping and gluing are completed. Then, the negative electrode tabs of the first electrode group 1 and the second electrode group 2 are bent in the direction of the electrode group.

[0101] Step 4, refer to Figure 5 As shown, the positive electrode side matching inlaid battery cover plate 4 is welded to the positive electrode lead piece 5; the specific welding method is laser welding.

[0102] Step 5, refer to Figure 6 As shown, the positive electrode lead piece 5 is welded to the positive electrode tabs of the first electrode group 1 and the second electrode group 2; the specific welding method is ultrasonic welding.

[0103] Step 6, refer to Figure 7 As shown, the first positive electrode tab 101 of the first electrode group 1 and the second positive electrode tab 201 of the second electrode group 2 are cross-connected together through a cross-bending operation.

[0104] Step 7, refer to Figure 8 As shown, two finished upper gasket brackets 6 are installed in a snap-fit manner at the positions between the positive electrode side matching inlaid battery cover plate 4 and the electrode group main body, and between the negative electrode side cover plate 3 and the electrode group main body. Then, a protective film is wrapped on the outer wall of the electrode group main body; among them, the first electrode group 1 and the second electrode group 2 are arranged side by side and stacked together to form the electrode group main body; therefore, through the upper gasket bracket 6, the electrode tabs can be protected and fixed, and the surface of the electrode group can be protected by wrapping the external protective film.

[0105] Step 8, refer to Figure 9As shown, insert the completed electrode group body with the coating into the barrel-shaped battery case 7. The specific operation is as follows: First, insert the positive electrode side into the battery case 7. When the positive electrode side's matching inlaid battery cover plate 4 passes through the battery case 7 and reaches the designated position (for example, a preset distance position near one end opening of the battery case 7), perform gravitational traction on the two traction posts 40 on the positive electrode side's matching inlaid battery cover plate 4 (an existing traction device with a clamping function can be used), so that the positive electrode side's matching inlaid battery cover plate 4 is cooperatively connected with the positive electrode cover plate flat 8 (the positive electrode cover plate flat 8 has a guiding groove structure that matches the positive electrode side's matching inlaid battery cover plate 4).

[0106] Step 9, refer to Figure 10 As shown, weld the four peripheries of the positive electrode cover plate flat 8 on the outer side of one end of the battery case 7 near the positive electrode side's matching inlaid battery cover plate 4. At the same time, weld the four peripheries of the other end of the battery case 7 to the four peripheries of the negative electrode side cover plate 3 to obtain a lithium-ion battery with two-sided electrode posts. The specific welding method can be laser welding.

[0107] Step 10, after completing the welding of the positive electrode cover plate flat 8 and the positive electrode side's matching inlaid battery cover plate 4, use a shearing method to cut off the two traction posts 40 on the positive electrode side's matching inlaid battery cover plate 4 (that is, cut off the protruding traction mechanism on the positive electrode side's matching inlaid battery cover plate 4).

[0108] In summary, compared with the prior art, a lithium-ion battery with two-sided electrode posts and an assembly method provided by the present invention are scientifically designed, can avoid the excessive length of the electrode tabs, effectively reduce the waste of electrode tab foils, and at the same time, effectively avoid the loss of space utilization rate in the height direction of the battery, which has great practical significance.

[0109] It should be noted that in the prior art, the welding operation is carried out after the battery is put into the case. Therefore, the length of the electrode tabs left in the prior art should consider the welding space during ultrasonic welding. For the battery structure adopted in the present invention, the welding of the electrode tabs and the corresponding cover plates is completed before the battery is put into the case. Thus, by applying the present invention, the reserved welding space for the ultrasonic welding head and the welding seat to extend into the battery case can be saved, and the saved part can be directly converted into the length of the electrode tabs and the utilization rate of the space.

[0110] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A lithium-ion battery with two-sided pole columns, characterized in that, It includes a first electrode group (1), a second electrode group (2), a negative electrode side cover plate (3), and a positive electrode side matching inlaid battery cover plate (4); The first electrode group (1) and the second electrode group (2) are juxtaposed and stacked on top of each other to form the main body of the electrode group; On both sides of the first electrode group (1), a first positive electrode tab (101) and a first negative electrode tab (102) are respectively provided; On both sides of the second electrode group (2), a second positive electrode tab (201) and a second negative electrode tab (202) are respectively provided; The first positive electrode tab (101) and the first negative electrode tab (102), as well as the second positive electrode tab (201) and the second negative electrode tab (202), are all multi-layer electrode tabs; The first negative electrode tab (102) of the first electrode group (1) and the second electrode group (2) are connected to the negative electrode side cover plate (3). The specific connection structure adopts any one of the following two: The first connection structure is: the first negative electrode tab (102) of the first electrode group (1) and the second negative electrode tab (202) of the second electrode group (2) are directly welded to a negative electrode side cover plate (3) at the same time; The second connection structure is: the first negative electrode tab (102) of the first electrode group (1) and the second negative electrode tab (202) of the second electrode group (2) are ultrasonically welded to a negative electrode lead piece, and the negative electrode lead piece is laser welded to the negative electrode side cover plate (3); At the center position of the negative electrode side cover plate (3), a negative electrode post (30) is provided; On one side surface of the positive electrode side matching inlaid battery cover plate (4), a positive electrode lead piece (5) is welded; At the center position of the other side surface of the positive electrode side matching inlaid battery cover plate (4), it is welded to a positive electrode post (440); Two positive electrode connection parts (50) are provided on the positive electrode lead piece (5); The two positive electrode connection parts (5) are respectively welded to the first positive electrode tab (101) of the first electrode group (1) and the second positive electrode tab (201) of the second electrode group (2); The positions between the positive electrode side matching inlaid battery cover plate (4) and the main body of the electrode group, and the positions between the negative electrode side cover plate (3) and the main body of the electrode group are respectively snapped to an upper gasket bracket (6); The outer wall of the main body of the electrode group is wrapped with a protective film; The main body of the electrode group wrapped with a protective film is placed into a battery case (7) with both ends open and hollow; Both ends of the battery case (7) are respectively snapped to an upper gasket bracket (6); On the outside of one end of the battery case (7) close to the positive electrode side matching inlaid battery cover plate (4), a positive electrode cover plate flat (8) is welded; The four peripheral edges of the negative electrode side cover plate (3) are welded to the four peripheral edges of the other end of the battery case (7).

2. The bipolar lithium-ion battery according to claim 1, characterized in that The first positive electrode tab (101) of the first electrode group (1) and the second positive electrode tab (201) of the second electrode group (2) connected by the two positive electrode connection parts (5) are cross-connected together through a cross-bending operation.

3. The bipolar lithium-ion battery according to claim 1, characterized in that, The two positive electrode connection parts (50) are respectively ultrasonically welded or laser welded to the first positive electrode tab (101) of the first electrode group (1) and the second positive electrode tab (201) of the second electrode group (2).

4. The bipolar lithium-ion battery according to claim 1, characterized in that, The edges of the first positive tab (101) and the first negative tab (102) of the first electrode group (1) do not exceed the center position of the tab setting surface of the first electrode group (1), and are biased towards the upper side or the lower side of the first electrode group (1). The second positive tab (201) and the second negative tab (202) of the second electrode group (2) do not exceed the center position of the tab setting surface of the second electrode group (2), and are biased towards the upper side or the lower side of the second electrode group (2).

5. The bipolar lithium-ion battery according to claim 1, wherein, The first positive tab (101) and the first negative tab (102) of the first electrode group (1), as well as the second positive tab (201) and the second negative tab (202) of the second electrode group (2), all use ultrasonic welding.

6. The bipolar lithium-ion battery according to claim 1, characterized in that, The positive side is equipped with an inlaid battery cover plate (4), which includes an outer pole column lead plate (41), an insulating washer (42), a cover plate main board (43), and a battery internal welding lead plate (44) stacked in sequence from outside to inside. The positive pole column (440) in the middle of the battery internal welding lead plate (44) sequentially passes through the central through hole of the cover plate main board (43) and the central through hole of the insulating washer (42), and then is inserted into the central through hole of the outer pole column lead plate (41). On the outer pole column lead plate (41), two traction columns (40) are arranged at intervals.

7. An assembly method for a lithium-ion battery with two-sided pole columns according to any one of claims 1-6, characterized in that, Specifically, it includes the following steps: Step 1, pre-weld the first positive tab (101) and the first negative tab (102) on both sides of the first electrode group (1), and pre-weld the second positive tab (201) and the second negative tab (202) on both sides of the second electrode group (2). Step 2, weld the first negative tab (102) of the pre-welded first electrode group (1) and the second negative tab (202) of the second electrode group (2) to the same negative side cover plate (3). Step 3, after the negative tabs of the first electrode group (1) and the second electrode group (2) are welded, bend the first electrode group (1) and the second electrode group (2) by 90 degrees, that is, fold them in half with each other, so that the first electrode group (1) and the second electrode group (2) are combined together to complete core encapsulation with glue, and then bend the negative tabs of the first electrode group (1) and the second electrode group (2) towards the direction of the electrode group. Step 4, weld the positive side inlaid battery cover plate (4) to the positive lead piece (5). Step 5, weld the positive lead piece (5) to the positive tabs of the first electrode group (1) and the second electrode group (2). Step 6, cross-connect the first positive tab (101) of the first electrode group (1) and the second positive tab (201) of the second electrode group (2) through a cross-bending operation. Step 7, install the two finished upper gasket brackets (6) in a snap-fit manner at the positions between the positive side inlaid battery cover plate (4) and the electrode group main body, and between the negative side cover plate (3) and the electrode group main body, and then wrap a protective film on the outer wall of the electrode group main body; among them, the first electrode group (1) and the second electrode group (2) are stacked side by side to form the electrode group main body. Step 8: Insert the completed enveloped electrode assembly body into the barrel-shaped battery case (7). The specific operation is as follows: First, insert the positive electrode side into the battery case (7). When the positive electrode side's matching inlaid battery cover plate (4) passes through the battery case (7) and reaches the designated position, apply gravitational traction to the two traction posts (40) on the positive electrode side's matching inlaid battery cover plate (4) so that the positive electrode side's matching inlaid battery cover plate (4) is cooperatively connected with the positive electrode cover plate flat (8). Step 9: Weld the four peripheral edges of the positive electrode cover plate flat (8) on the outer side of one end of the battery case (7) close to the positive electrode side's matching inlaid battery cover plate (4). At the same time, weld the four peripheral edges of the other end of the battery case (7) to the four peripheral edges of the negative electrode side cover plate (3) to obtain a lithium-ion battery with two-sided electrode posts. Step 10: After completing the welding of the positive electrode cover plate flat (8) and the positive electrode side's matching inlaid battery cover plate (4), cut off the two traction posts (40) on the positive electrode side's matching inlaid battery cover plate (4) by shearing.

8. The assembling method of the lithium-ion battery with two-sided pole columns according to claim 7, wherein, In Step 2, the first negative electrode tab (102) of the first electrode assembly (1) and the second negative electrode tab (202) of the second electrode assembly (2) are ultrasonically welded to a negative electrode lead piece, and the negative electrode lead piece is laser welded to the negative electrode side cover plate (3).

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