Battery cells and lithium-ion batteries

Abstract

The present invention provides a battery cell comprising a plurality of stacked first pole pieces and a plurality of second pole pieces, wherein the first pole pieces and the second pole pieces have opposite polarities, the first pole piece comprising a first A pole piece and a first B pole piece, the first A pole piece being electrically connected to a first A tab, one end of the first B pole piece extending outward to form a first B tab, the first A tab and the first B tab being electrically connected, and at least one first A pole piece in the battery cell. The present invention also provides a lithium-ion battery. The present invention overcomes the problem of tabs of the same polarity being easily fractured under stress when electrically connected, thereby reducing the scrap rate of the battery cell.

Description

Technical Field

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

[0002] The laminated lithium-ion battery has a low internal resistance, which enables it to support high-rate charging and discharging, thus meeting the demand for fast battery charging. Therefore, it has become an important development direction for lithium-ion batteries.

[0003] Existing laminated lithium-ion batteries include multiple stacked positive and negative electrode sheets. Each positive sheet is die-cut to form a positive tab, and each negative sheet is die-cut to form a negative tab. All positive tabs are folded and electrically connected to an external positive tab, and all negative tabs are folded and electrically connected to an external negative tab. One of the external positive tab and the external negative tab is electrically connected to the outer casing of the lithium-ion battery, and the other of the external positive tab and the external negative tab is electrically connected to the conductive cover of the lithium-ion battery.

[0004] However, when bending the tabs or electrically connecting the bent tabs of the same polarity to external tabs, the tabs are easily broken by stress during electrical connection, causing the lithium-ion battery stack to be scrapped. Summary of the Invention

[0005] The present invention provides a battery cell and a lithium battery, which overcome the problem in the prior art that tabs are easily broken by stress during electrical connection, thereby reducing the scrap rate of the battery cell.

[0006] According to an embodiment of the present invention, on the one hand, a battery cell is provided, comprising a plurality of first pole pieces and a plurality of second pole pieces stacked together, wherein the first pole piece and the second pole piece have opposite polarities, the first pole piece comprises a first A pole piece and a first B pole piece, the first A pole piece is electrically connected to a first A pole tab, one end of the first B pole piece extends outward to form a first B pole tab, the first A pole tab and the first B pole tab are electrically connected, and there is at least one first A pole piece in the battery cell.

[0007] In one possible implementation, the first pole pieces are stacked sequentially in the thickness direction of the battery cell, and the number of the first pole pieces is N, and the first pole piece arranged in the i-th position in the thickness direction of the battery cell is the first A pole piece, where 30%≤i / N≤70%.

[0008] In one possible implementation, any surface of the first A tab is electrically connected to at most 50 of the first B tabs.

[0009] In one possible implementation, the second pole piece includes a second A pole piece and a second B pole piece, the second A pole piece is electrically connected to the second A pole ear, one end of the second A pole piece extends outward to form a second B pole ear, and the second A pole ear and the second B pole ear are electrically connected; the second pole pieces are stacked in sequence in the thickness direction of the battery cell, and the number of the second pole pieces is M, the second pole piece ranked kth in the thickness direction of the battery cell is the second A pole piece, where 30%≤k / M≤70%.

[0010] In one possible implementation, any surface of the second A-tab is electrically connected to at most 50 of the second B-tabs.

[0011] In one possible implementation, the first electrode sheet includes a first current collector and a first active material layer; the first A electrode tab is welded to the first current collector, the first active material layer is coated on the surface of the first current collector and surrounds the portion of the first A electrode tab located on the first current collector, and the ratio of the weld mark height of the first A electrode tab to the thickness of the first A electrode tab is 0 to 2; the first B electrode tab is integrally formed with the positive electrode current collector and is located on the outside of the positive electrode current collector, and the first active material layer is coated on the surface of the positive electrode current collector.

[0012] In one possible implementation, the thickness of the first A tab is 10 to 500 μm, the length of the first A tab is 5 to 200 mm, and the width of the first A tab is 2 to 50 mm; the thickness of the first B tab is 6 to 20 μm, the length of the first B tab is 5 to 200 mm, and the width of the first B tab is 2 to 50 mm.

[0013] In a possible implementation, the second pole piece includes a second current collector and a second active material layer;

[0014] The second A tab is welded to the second current collector, the second active material layer is coated on the surface of the second current collector and surrounds the portion of the second A tab located on the first current collector, and the ratio of the weld mark height of the second A tab to the thickness of the second A tab is 0 to 2;

[0015] The second B tab is integrally formed with the second current collector and is located outside the second current collector, and the second active material layer is coated on the surface of the second current collector.

[0016] In a possible implementation, the thickness of the second A tab is 10 to 500 μm, the length of the second A tab is 5 to 200 mm, and the width of the second A tab is 2 to 50 mm.

[0017] The thickness of the second B tab is 4 to 20 μm, the length of the second B tab is 5 to 200 mm, and the width of the second B tab is 2 to 50 mm.

[0018] According to another aspect of an embodiment of the present invention, a lithium-ion battery is provided, comprising a battery housing, an electrolyte, and the battery cell described above.

[0019] The present invention provides a battery cell and lithium battery. The present invention provides a battery cell with two tab combinations, including at least one first A tab and a die-cut first B tab. Therefore, during electrical connection, the die-cut first B tab and the first B tab are bent at a moderate angle, thereby enabling the first B tab to be stably electrically connected to the first A tab. Furthermore, the first B tab electrically connected to the surface of the first A tab is less susceptible to fracture due to stress during bending or electrical connection, thereby reducing the battery cell's scrap rate. Furthermore, the first A tabs are disposed on the pole piece, saving battery space and increasing volume density. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0021] Figure 1 A schematic diagram of the cross-sectional structure of the first A-tab side of a battery cell provided by an embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the cross-sectional structure of the first A-tab side of another battery cell provided by an embodiment of the present invention;

[0023] Figure 3 A schematic diagram of the cross-sectional structure of the second B-tab side of another battery cell provided by an embodiment of the present invention;

[0024] Figure 4 A schematic structural diagram of a first A pole piece provided by an embodiment of the present invention;

[0025] Figure 5 A schematic structural diagram of a first B pole piece provided in an embodiment of the present invention;

[0026] Figure 6 A schematic structural diagram of a second A pole piece provided by an embodiment of the present invention;

[0027] Figure 7 A schematic structural diagram of a second B pole piece provided in an embodiment of the present invention;

[0028] Figure 8 A schematic diagram of the cross-sectional structure of the second A-tab side of another battery cell provided by an embodiment of the present invention;

[0029] Figure 9 A schematic diagram of the cross-sectional structure of the second B-tab side of another battery cell provided by an embodiment of the present invention;

[0030] Figure 10 A schematic diagram of the lithium-ion battery structure provided by an embodiment of the present invention.

[0031] Reference numerals:

[0032] 10-first A pole piece;

[0033] 101 - first current collector; 102 - first active material layer; 103 - first A tab;

[0034] 20-first B pole piece;

[0035] 201-first B tab;

[0036] 30-second A pole piece;

[0037] 301 - second current collector; 302 - second active material layer; 303 - second A tab;

[0038] 40-second B pole piece;

[0039] 401-second B tab;

[0040] 50-diaphragm;

[0041] 60-Lithium-ion battery.

[0042] The above drawings illustrate specific embodiments of the present disclosure, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the present disclosure in any way, but rather to illustrate the concepts of the present disclosure to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0043] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0044] It should be noted that the words indicating directions such as "up", "down", "left", "right", "inside" and "outside" used in this disclosure are based on the directions shown in the accompanying drawings unless otherwise specified. However, it should be understood that this is only for the convenience of description and is not a specific limitation on the product orientation.

[0045] Additionally, in this disclosure, unless otherwise specified, “connected” may refer to two objects being directly connected or being indirectly connected via an intermediate object.

[0046] Finally, “first” and “second” in this disclosure are only used to distinguish structures, and do not represent the order of precedence or the number of the structures.

[0047] The existing laminated lithium-ion battery includes a plurality of first and second pole pieces with opposite polarities stacked together. The pole tabs of the same polarity in the first or second pole piece need to be electrically connected together. The pole tabs of the existing pole pieces are formed by die-cutting, that is, the pole tabs and the pole piece are formed as one piece. After being bent, all the pole tabs are electrically connected to an external pole tab. When the corresponding bent pole tabs or the bent pole tabs are electrically connected to the external pole tabs, the pole tabs formed by die-cutting are very thin and are easily broken by stress during bending / electrical connection, resulting in the scrapping of the lithium-ion battery stack.

[0048] In view of this, the present invention electrically connects the first A pole piece of the first pole piece among the stacked multiple first pole pieces and the multiple second pole pieces to the first A pole ear, and one end of the first B pole piece in the first pole piece extends outward to form the first B pole ear. The first A pole ear and the first B pole ear are electrically connected, and at the same time, there is at least one first A pole piece in the battery cell, thereby reducing the bending degree of the first A pole ear and the first B pole ear, and avoiding the first B pole ear and the first A pole ear formed by die cutting from being fractured by stress during bending and electrical connection.

[0049] It is worth noting that since the first A pole ear is electrically connected to the first pole piece, the thickness of the first A pole ear is greater than the thickness of the first B pole ear formed by die cutting, thereby further reducing the stress fracture phenomenon that occurs when the first B pole ear is electrically connected to the first A pole ear; the first A pole ear can be a positive pole ear or a negative pole ear, the first B pole ear can be a positive pole ear or a negative pole ear, and the polarity of the first A pole ear and the first B pole ear is the same.

[0050] The following is an introduction to typical implementations of the present invention in conjunction with the accompanying drawings so that those skilled in the art can more clearly understand the solutions of the present disclosure. It should be noted that one or some structures in the different implementations described below can be replaced with each other, and the implementations of the present disclosure are not limited to the following examples. Under the above concept, those skilled in the art can also derive other possible implementations based on the examples below, and these implementations should also be regarded as the contents of the present disclosure.

[0051] Figure 1 A schematic diagram of the cross-sectional structure of the first A-pole ear side of a battery cell is shown. Figure 1The battery cell provided includes a first A pole piece 10, a first B pole piece 20 and a second B pole piece 40 that are stacked. The first A pole piece 10 is electrically connected to the first A pole piece 103. One end of the first B pole piece 20 extends outward to form a first B pole piece 201, that is, the first B pole piece 201 is an existing die-cut pole piece. One end of the second B pole piece 40 extends outward to form a second B pole piece 401, that is, the second B pole piece 401 is an existing die-cut pole piece. The first A pole piece 103 and the first B pole piece 201 of the same polarity are electrically connected, and two adjacent second B pole pieces 401 are electrically connected.

[0052] Specifically, Figure 1 The cell shown includes a first A pole piece 10 and four first B pole pieces 20, wherein two first B pole pieces 20 are stacked below the first A pole piece 10, and the other two first B pole pieces 20 are stacked above the first A pole piece 10. In other words, Figure 1 The first A pole piece 10 is located at the center of the four first B pole pieces 20. The upper surface of the first A pole piece 103 electrically connected to the first A pole piece 10 is electrically connected to two first B pole pieces 201, and the lower surface of the first A pole piece 103 is electrically connected to the other two first B pole pieces 201. Based on this, the upper and lower surfaces of the first A pole piece 103 are electrically connected to the same number of first B pole pieces 201. In this way, on the one hand, the bending degree of each first B pole piece 201 can be relatively low, thereby reducing the probability of the first B pole piece 201 breaking when bending. On the other hand, the first B pole pieces 201 above and below the first A pole piece 103 are symmetrical, which is beneficial to the heat dissipation and packaging of the battery cell. At the same time, the first A pole piece 103 is arranged on the pole piece, which can save battery space and increase volume density.

[0053] It should be pointed out that Figure 1 The arrangement and number of the first A pole piece 10 and the first B pole piece 20 shown in the figure are only schematic. In some other examples, the number of the first B pole piece 201 electrically connected to the first A pole piece 103 and the position of the first A pole piece 103 in the first pole piece along the thickness direction of the battery cell are limited to avoid the first B pole piece 201 from breaking due to excessive bending during the electrical connection process. For example, when the number of the first B pole pieces 201 electrically connected to each surface of the first A pole piece 103 does not exceed 50 and the first pole piece is stacked in sequence in the thickness direction of the battery cell, and the number of first pole pieces is N, the first pole piece arranged in the i-th row in the thickness direction of the battery cell is the first A pole piece 10, where 30%≤i / N≤70%. At this time, the first A pole piece 10 and the first B pole piece 20 can have any suitable number and any suitable arrangement.

[0054] in, Figure 1The electrical connection between the first A tab 103 and the first B tab 201 can be specifically welded. In other embodiments, the electrical connection between the tabs of the same sex and the electrical connection between the tabs and the corresponding electrode pieces are preferably welded. The first B tab 201 is a die-cut tab. Die-cutting specifically refers to cutting the electrode piece with a very small gap between the punch and the lower die. In other embodiments, die-cutting also refers to cutting the electrode piece with a very small gap between the punch and the lower die.

[0055] It is worth noting that the stacking method of the first A electrode 10, the first B electrode 20 and the second B electrode 40 can adopt a negative-positive alternating stacking method, that is, a corresponding positive electrode is provided between adjacent negative electrodes, wherein the first A electrode 10 and the first B electrode 20 can be either a positive electrode or a negative electrode. Figure 1 In the embodiment, the battery cell is composed of a first A pole piece 10, a second A pole piece 30, and six first B pole pieces 20 stacked together. Specifically, three second B pole pieces 40 are stacked above the first A pole piece 10, and three second B pole pieces 40 are stacked below the first A pole piece 10. As a result, the six second B pole pieces 40 form five gaps. The first A pole piece 10 is located in the middle gap, and the corresponding first B pole pieces 20 are located in the remaining four gaps.

[0056] Continue to refer Figure 1 To prevent electrodes with opposite polarities from directly contacting each other, a diaphragm 50 is provided between two adjacent electrodes. The diaphragm 50 may include a substrate and a coating layer. The substrate may be a polyethylene single-layer film, a polypropylene single-layer film, or a polypropylene-polyethylene-polypropylene three-layer composite film. The coating layer may be at least one of porous silica, alumina, titanium dioxide, and zirconium dioxide.

[0057] In another possible implementation, please refer to Figure 1 In order to facilitate the electrical connection of the tabs together and facilitate the electrical connection of the tabs after electrical connection with external connecting wires, the first B tab 201 can be welded to the middle of the first A tab 103.

[0058] Figure 2 A schematic diagram of the cross-sectional structure of the first A-pole tab side of another battery cell is shown. Figure 3 The cross-sectional structure diagram of the first B-pole tab side of another battery cell is shown. Figure 2 and Figure 3The battery cell provided includes a first A pole piece 10, a first B pole piece 20, a second A pole piece 30, and a second B pole piece 40 that are stacked. The first A pole piece 10 and the first B pole piece 20 have the same polarity, the second A pole piece 30 and the second B pole piece 40 have the same polarity, and the first A pole piece 10 and the second A pole piece 30 have opposite polarities. The first A pole piece 10 is electrically connected to the first A pole tab 103, and one end of the first B pole piece 20 extends outward to form a first B pole tab 201, that is, the first B pole tab 201 is an existing die-cut pole tab. The second A pole piece 30 is electrically connected to the second A pole tab 303, and one end of the second B pole piece 40 extends outward to form a second B pole tab 401, that is, the second B pole tab 401 is an existing die-cut pole tab.

[0059] Specifically, Figure 2 The cell is shown to include a first A-pole sheet 10 and four first B-pole sheets 20, wherein two first B-pole sheets 20 are stacked below the first A-pole sheet 10, and the other two first B-pole sheets 20 are stacked above the first A-pole sheet 10. In other words, Figure 2 The first A pole piece 10 is located at the center of the four first B pole pieces 20. The upper surface of the first A pole piece 10 is electrically connected to the first B pole piece 103, which is formed by die-cutting the two first B pole pieces 20 above the first A pole piece 10. The lower surface of the first A pole piece 103 is electrically connected to the first B pole piece 201 formed by die-cutting the two first B pole pieces 20 below the first A pole piece 10. Based on this, the upper and lower surfaces of the first A pole piece 103 are electrically connected to the same number of first B pole pieces 201. In this way, on the one hand, the bending degree of each first B pole piece 201 can be relatively low, thereby reducing the probability of the first B pole piece 201 breaking when bending. On the other hand, the first B pole pieces 201 above and below the first A pole piece 103 are symmetrical, which is beneficial to the heat dissipation and packaging of the battery cell. At the same time, the first A pole piece 103 is arranged on the pole piece, which can save battery space and provide volume density.

[0060] Similarly, Figure 3 The figure shows that the battery cell further includes a second A pole piece 30 and five second B pole pieces 40, wherein three second B pole pieces 40 are stacked below the second A pole piece 30, and the other two second B pole pieces 40 are stacked above the second A pole piece 30. In other words, Figure 3The second A pole piece 30 is located in the middle of the five second B pole pieces 40. The upper surface of the second A pole piece 303 electrically connected to the second A pole piece 30 is electrically connected to the second B pole piece 401 formed by die-cutting the two second B pole pieces 40 above the second A pole piece 30. The lower surface of the second A pole piece 303 is electrically connected to the second B pole piece 401 formed by die-cutting the three second B pole pieces 40 below the second A pole piece 303. Based on this, the bending degree of each second B pole piece 401 can be made relatively low, thereby reducing the probability of the second B pole piece 401 breaking when bending. At the same time, the second A pole piece 303 is arranged on the pole piece, which can save battery space and increase volume density.

[0061] It should be pointed out that Figure 2 The arrangement and number of the first A pole piece 10 and the first B pole piece 20 shown in the figure are only schematic. In some other examples, the number of the first B pole piece 201 electrically connected to the first A pole piece 103 and / or the position of the first A pole piece 103 in the first pole piece along the thickness direction of the battery cell is limited to avoid the first B pole piece 201 from breaking due to excessive bending during the electrical connection process. For example, when the number of the first B pole pieces 201 electrically connected to each surface of the first A pole piece 103 does not exceed 50 and / or the first pole piece is stacked in sequence in the thickness direction of the battery cell, and the number of first pole pieces is N, the first pole piece arranged in the i-th row in the thickness direction of the battery cell is the first A pole piece, where 30%≤i / N≤70%. At this time, the first A pole piece 10 and the first B pole piece 20 can have any suitable number and any suitable arrangement.

[0062] Accordingly, Figure 3 The arrangement and number of the second A pole piece 30 and the second B pole piece 40 shown in the figure are only schematic. In some other examples, the second B pole piece 401 is prevented from breaking due to excessive bending during the electrical connection process by limiting the number of second B pole pieces 401 electrically connected to the second A pole piece 303 and / or limiting the position of the second A pole piece 303 in the second pole piece along the thickness direction of the battery cell. For example, when the number of second B pole pieces 401 electrically connected to each surface of the second A pole piece 303 does not exceed 50 and the first pole piece is stacked in sequence in the thickness direction of the battery cell, and the number of second pole pieces is M, the first pole piece ranked kth in the thickness direction of the battery cell is the second A pole piece 30, where 30%≤k / M≤70%. At this time, the second A pole piece 30 and the second B pole piece 40 can have any suitable number and any suitable arrangement.

[0063] It is worth noting that the stacking method of the first A electrode 10, the first B electrode 20, the second A electrode 30 and the second B electrode 40 can adopt a negative-positive alternating stacking method, that is, corresponding positive electrodes are provided between adjacent negative electrodes. Figure 2 and Figure 3In the embodiment, the battery cell is stacked by a first A pole piece 10, a second A pole piece 30, four first B pole pieces 20, and five second B pole pieces 40. Specifically, two second B pole pieces 40 are stacked above the second A pole piece 30, and three second B pole pieces 40 are stacked below the second A pole piece 30. Thus, one second A pole piece 30 and five second B pole pieces 40 form five gaps. The first A pole piece 10 is located in the middle gap, and the corresponding first B pole pieces 20 are located in the remaining four gaps.

[0064] Continue to refer Figure 2 、 Figure 3 To prevent electrodes with opposite polarities from directly contacting each other, a diaphragm 50 is provided between two adjacent electrodes. The diaphragm 50 may include a substrate and a coating layer. The substrate may be a polyethylene single-layer film, a polypropylene single-layer film, or a polypropylene-polyethylene-polypropylene three-layer composite film. The coating layer may be at least one of porous silica, alumina, titanium dioxide, and zirconium dioxide.

[0065] In another possible implementation, please refer to Figure 2 、 Figure 3 In order to facilitate the electrical connection of the tabs together and facilitate the connection of the electrically connected tabs to external connecting wires, the first B tab 201 can be welded to the middle of the first A tab 103, and the second B tab 401 can be welded to the middle of the second A tab 303.

[0066] Figure 4 A schematic diagram of the structure of the first A pole piece is shown. Figure 4 In an optional implementation, the first A pole piece 10 may include a first current collector 101 and a first active material layer 102, wherein one surface of the first current collector 101 includes an electrical connection area and a coating area surrounding the electrical connection area, the first A pole piece 103 is welded to the electrical connection area, and the first active material layer 102 is coated on the coating area and the other surface of the first current collector 101.

[0067] by Figure 4 For example, an electrical connection area is provided on the upper left side of the front surface of the first current collector 101, the first A pole ear 103 is electrically connected to the electrical connection area and extends upward and exceeds the upper boundary of the first current collector 101, and the first active material layer 102 is coated on the area of ​​the front surface of the first current collector 101 except the electrical connection area and the rear surface of the first current collector 101, that is, the first active material layer 102 coated on the front surface of the first current collector 101 surrounds the electrical connection area and the first A pole ear 103 welded in the electrical connection area from the left, right and bottom.

[0068] Schematically, when the first electrode sheet is a positive electrode sheet, the first current collector 101 can be aluminum foil, and the first active material layer 102 can be made of lithium cobalt oxide, lithium iron phosphate and manganese-rich lithium materials, wherein the first active material layer 102 can be a single lithium cobalt oxide, lithium iron phosphate and manganese-rich lithium, or it can be a mixture of any two of lithium cobalt oxide, lithium iron phosphate and manganese-rich lithium, or it can be a mixture of lithium cobalt oxide, lithium iron phosphate and manganese-rich lithium in a certain proportion.

[0069] The first A-type tab 103 can be electrically connected to the first current collector 101 by laser welding, ultrasonic welding, or other electrical connection methods. Optionally, the thickness of the first A-type tab 103 can be 10 to 500 μm, the length of the first A-type tab 103 can be 5 to 200 mm, and the width of the first A-type tab 103 can be 2 to 50 mm, so as to facilitate the electrical connection between the first A-type tab 103 and the first current collector 101 and reduce the possibility of breakage when the first B-type tab 201 is electrically connected to the first A-type tab 103.

[0070] Optionally, the ratio of the weld height between the first A pole tab 103 and the first current collector 101 to the thickness of the first A pole tab 103 can be 0 to 2, and the pole tab electrical connection tension is ≥ 10 N / m to avoid breakage of the first A pole tab 103 during electrical connection, and also to reduce possible breakage when the first B pole tab 201 is electrically connected to the first A pole tab 103.

[0071] It is worth noting that the first active material layer 102 can be coated on the front and rear surfaces of the first current collector 101 after the first A tab 103 is welded to the first current collector 101, thereby forming the first A pole piece 10. Of course, the first A tab 103 can also be welded after the first active material layer 102 is coated.

[0072] Figure 5 A schematic diagram of the structure of the first B pole piece is shown. Figure 5 In another possible implementation, the first B pole piece 20 may include a first current collector 101 and a first active material layer 102, wherein the first current collector 101 is integrally formed with a first B pole tab 201 by die-cutting, the first B pole tab 201 is located on the outside of the first current collector 101, and the first active material layer 102 is coated on the surface of the first current collector 101.

[0073] by Figure 5 For example, the front end of the front surface of the first current collector 101 is die-cut to form a first B pole tab 201, the first B pole tab 201 extends upward and exceeds the upper boundary of the first current collector 101, and the first active material layer 102 is coated on the surface of the first current collector 101 except the first B pole tab 201.

[0074] The first B-type tab 201 can be obtained by directly die-cutting on the first current collector 101 of the first B-type tab 20. Optionally, the thickness of the first B-type tab 201 is 6 to 20 μm, the length of the first B-type tab 201 can be 5 to 200 mm, and the width of the first B-type tab 201 can be 2 to 50 mm, so as to reduce the possibility of breakage when the first B-type tab 201 and the first A-type tab 103 are electrically connected.

[0075] Figure 6 A schematic diagram of the structure of the second A pole piece is shown. Figure 6 In one feasible manner, the second A pole piece 30 may include a second current collector 301 and a second active material layer 302, wherein one surface of the second current collector 301 includes an electrical connection area and a coating area surrounding the electrical connection area, the second A pole piece 303 is welded to the electrical connection area, and the second active material layer 302 is coated on the coating area and the other surface of the second current collector 301.

[0076] by Figure 6 For example, an electrical connection area is provided on the upper left side of the front surface of the second current collector 301, the second A pole ear 303 is welded to the electrical connection area and extends upward and exceeds the upper boundary of the second current collector 301, and the second active material layer 302 is coated on the area other than the electrical connection area on the front surface of the second current collector 301 and the rear surface of the second current collector 301, that is, the second active material layer 302 coated on the front surface of the second current collector 301 surrounds the electrical connection area and the second A pole ear 303 electrically connected to the electrical connection area from the left, right and bottom.

[0077] Schematically, when the second A pole piece 30 is a negative pole piece, the second current collector 301 can be a copper foil, and the second active material layer 302 can be made by mixing graphite, hard carbon, silicon and silicon oxide materials, wherein the second active material layer 302 can be made of graphite, hard carbon, silicon and silicon oxide materials individually, or can be made by mixing any two or three of graphite, hard carbon, silicon and silicon oxide, or can be made by mixing all four in a certain proportion.

[0078] The second A tab 303 can be electrically connected to the second current collector 301 by laser welding or ultrasonic welding. Optionally, the thickness of the second A tab 303 can be 10 to 500 μm, the length of the second A tab 303 can be 5 to 200 mm, and the width of the second A tab 303 can be 2 to 50 mm, so as to facilitate welding of the second A tab 303 and the second current collector 301 and reduce possible breakage during welding of the second B tab 401 and the second A tab 303.

[0079] Optionally, the ratio of the weld height between the second A pole tab 303 and the second current collector 301 to the thickness of the second A pole tab 303 can be 0 to 2, and the pole tab electrical connection tension is ≥30 N / m to avoid breakage of the second A pole tab 303 during electrical connection, and also to reduce the possible breakage when the second B pole tab 401 is electrically connected to the second A pole tab 303.

[0080] It is worth noting that after the second A tab 303 is welded to the second current collector 301, the second active material layer 302 can be coated on the front and rear surfaces of the second current collector 301 to form the second A pole piece 30. Of course, the second A tab 303 can also be welded after the second active material layer 302 is coated.

[0081] Figure 7 A schematic diagram of the structure of the second B pole piece is shown. Figure 7 In one possible implementation, the second B pole piece 40 may include a second current collector 301 and a second active material layer 302, wherein the second current collector 301 is integrally formed with a second B pole tab 401 by die-cutting, the second B pole tab 401 is located on the outside of the second current collector 301, and the second active material layer 302 is coated on the surface of the second current collector 301.

[0082] by Figure 7 For example, a second B-pole tab 401 is die-cut at the front end of the front surface of the second current collector 301 , the second B-pole tab 401 extends upward and exceeds the upper boundary of the second current collector 301 , and the second active material layer 302 is coated on the surface of the second current collector 301 except the second B-pole tab 401 .

[0083] The second B-pole tab 401 can be obtained by directly die-cutting on the second current collector 301 of the second B-pole sheet 40. Optionally, the thickness of the second B-pole tab 401 is 4 to 20 μm, the length of the second B-pole tab 401 can be 5 to 200 mm, and the width of the second B-pole tab 401 can be 2 to 50 mm, so as to reduce the possibility of breakage when the second B-pole tab 401 is electrically connected to the second A-pole tab 303.

[0084] Figure 8 A schematic diagram of the cross-sectional structure of the positive electrode tab side of another battery cell is shown; Figure 9 A schematic diagram of the cross-sectional structure of the negative electrode ear side of another battery cell is shown. Figure 8 and Figure 9The battery cell provided includes a first A pole piece 10, a first B pole piece 20, a second A pole piece 30, and a second B pole piece 40 that are stacked. The first A pole piece 10 and the first B pole piece 20 have the same polarity, the second A pole piece 30 and the second B pole piece 40 have the same polarity, and the first A pole piece 10 and the second A pole piece 30 have opposite polarities. The first A pole piece 10 is electrically connected to the first A pole tab 103, and one end of the first B pole piece 20 extends outward to form a first B pole tab 201, that is, the first B pole tab 201 is an existing die-cut pole tab. The second A pole piece 30 is electrically connected to the second A pole tab 303, and one end of the second B pole piece 40 extends outward to form a second B pole tab 401, that is, the second B pole tab 401 is an existing die-cut pole tab.

[0085] Specifically, Figure 8 It is shown that the battery cell includes two first A pole sheets 10 and eight first B pole sheets 20, wherein one first A pole sheet 10 is located in the upper middle part of the battery cell, and the other first A pole sheet 10 is located in the lower middle part of the battery cell. Two first B pole sheets 20 are stacked above the first A pole sheet 10 in the upper middle part of the battery cell, four first B pole sheets 20 are stacked between the two first A pole sheets 10, and two first B pole sheets 20 are stacked below the first A pole sheet 10 in the lower middle part of the battery cell. The upper surface of the first A pole ear 103 electrically connected to the first A pole piece 10 located in the upper middle part of the battery cell is electrically connected to the first B pole ear 201 die-cut by the two first B pole pieces 20 above the first A pole piece 10, and the lower surface of the first A pole ear 103 in the upper middle part is electrically connected to the first B pole ear 201 die-cut by the two first B pole pieces 20 immediately below the first A pole piece 10; the upper surface of the first A pole ear 103 electrically connected to the first A pole piece 10 located in the lower middle part of the battery cell is electrically connected to the first B pole ear 201 die-cut by the two first B pole pieces 20 immediately above the first A pole piece 10 in the lower middle part, and the lower surface of the first A pole ear 103 in the lower middle part is electrically connected to the first B pole ear 201 die-cut by the two first B pole pieces 20 below it. Based on this, one first A pole piece 10 is located in the upper middle portion of the battery cell, and another first A pole piece 10 is located in the lower middle portion of the battery cell. The eight first B pole tabs 201 are electrically connected to the first A pole tab 103 of the corresponding first A pole piece 10 nearby. This reduces the bending degree of each first B pole tab 201, thereby reducing the probability of the first B pole tab 201 breaking when bent. At the same time, the first A pole tab 103 is arranged on the pole piece, which can save battery space and increase volume density.

[0086] Similarly, Figure 9It is shown that the battery cell also includes two second A pole sheets 30 and nine second B pole sheets 40, wherein one second A pole sheet 30 is located in the middle and upper part of the battery cell, and the other second A pole sheet 30 is located in the middle and lower part of the battery cell. Two second B pole sheets 40 are stacked above the second A pole sheet 30 in the middle and upper part of the battery cell, five second B pole sheets 40 are stacked between the two second A pole sheets 30, and two second B pole sheets 40 are stacked below the second A pole sheet 30 in the middle and lower part of the battery cell. The upper surface of the second A pole ear 303 electrically connected to the second A pole piece 30 located in the upper middle part of the battery cell is electrically connected to the second B pole ear 401 die-cut by the two second B pole pieces 40 above the second A pole piece 30 in the upper middle part, and the lower surface of the second A pole ear 303 in the upper middle part is electrically connected to the second B pole ear 401 die-cut by the three second B pole pieces 40 immediately below the second A pole piece 30 in the upper middle part; the upper surface of the second A pole ear 303 electrically connected to the second A pole piece 30 located in the lower middle part of the battery cell is electrically connected to the second B pole ear 401 die-cut by the two second B pole pieces 40 immediately above the second A pole piece 30 in the lower middle part, and the lower surface of the second A pole ear 303 in the lower middle part is electrically connected to the second B pole ear 401 die-cut by the two second B pole pieces 40 below it. Based on this, one second A pole piece 30 is located in the upper middle portion of the cell, and another second A pole piece 30 is located in the lower middle portion of the cell. The nine second B pole tabs 401 are electrically connected to the second A pole tabs 303 of the corresponding second A pole piece 30. This reduces the bending degree of each second B pole tab 401, thereby reducing the probability of the second B pole tab 401 breaking when bent. At the same time, the second A pole tab 303 is arranged on the pole piece, which can save battery space and increase volume density.

[0087] It is worth noting that the stacking method of the first A pole piece 10, the first B pole piece 20, the second A pole piece 30 and the second B pole piece 40 in the battery cell adopts a negative-positive alternating stacking method, that is, the polarity of the two adjacent pole pieces is opposite. Figure 8 and Figure 9 In the embodiment, the battery cell is stacked by two first A pole pieces 10, two second A pole pieces 30, eight first B pole pieces 20 and nine second B pole pieces 40. Specifically, two second B pole pieces 40 are stacked above the second A pole piece 30 located in the upper middle part of the battery cell, five second B pole pieces 40 are stacked between the second A pole piece 30 in the upper middle part of the battery cell and the second A pole piece 30 in the lower middle part of the battery cell, and two second B pole pieces 40 are stacked below the second A pole piece 30 in the lower middle part of the battery cell. Thus, the two second A pole pieces 30 and the nine second B pole pieces 40 form ten gaps, wherein a first A pole piece 10 is provided in the gap immediately below the second A pole piece 30 in the upper middle part, another first A pole piece 10 is provided in the gap immediately above the second A pole piece 30 in the lower middle part, and corresponding first B pole pieces 20 are provided in the remaining eight gaps.

[0088] Of course, it should be pointed out that Figure 8 The arrangement and number of the first A pole piece 10 and the first B pole piece 20 shown in the figure are only schematic. In some other examples, the number of the first B pole piece 201 electrically connected to the first A pole piece 103 and the position of the first A pole piece 103 in the first pole piece along the thickness direction of the battery cell are limited to avoid the first B pole piece 201 from breaking due to excessive bending during the electrical connection process. That is, when the number of the first B pole pieces 201 electrically connected to each surface of the first A pole piece 103 does not exceed 50 and the first pole piece is stacked in sequence in the thickness direction of the battery cell, and the number of first pole pieces is N, the first pole piece ranked i-th in the thickness direction of the battery cell is the first A pole piece, where 30%≤i / N≤70%. At this time, the first A pole piece 10 and the first B pole piece 20 can have any suitable number and any suitable arrangement.

[0089] Accordingly, Figure 9 The arrangement and number of the second A pole piece 30 and the second B pole piece 40 shown in the figure are only schematic. In some other examples, the second B pole piece 401 is prevented from breaking due to excessive bending during the electrical connection process by limiting the number of second B pole pieces 401 electrically connected to the second A pole piece 303 and limiting the position of the second A pole piece 303 in the second pole piece along the thickness direction of the battery cell. That is, when the number of second B pole pieces 401 electrically connected to each surface of the second A pole piece 303 does not exceed 50 and the first pole piece is stacked in sequence in the thickness direction of the battery cell, and the number of second pole pieces is M, the first pole piece ranked kth in the thickness direction of the battery cell is the second A pole piece 30, where 30%≤k / M≤70%. At this time, the second A pole piece 30 and the second B pole piece 40 can have any suitable number and any suitable arrangement.

[0090] Figure 10 A schematic diagram of the structure of a lithium-ion battery is shown. Figure 10 The lithium-ion battery 60 provided in this embodiment includes a battery casing, an electrolyte, and any of the battery cells described above.

[0091] Schematically, when preparing the lithium-ion battery 60, the cells can be stacked in the order of positive electrode sheet - separator - negative electrode sheet - separator. During stacking, the stacking order and number of the first A-pole sheet 10 and the first B-pole sheet 20, as well as the second A-pole sheet 30 and the second B-pole sheet 40, should be as described above. After the cells are stacked, electrolyte is injected, the cells are sealed, and then the battery case is installed to form the finished lithium-ion battery 60.

[0092] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the following claims.

[0093] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A battery cell comprising a plurality of first pole pieces and a plurality of second pole pieces stacked together, wherein the first pole pieces and the second pole pieces have opposite polarities, characterized in that: The first pole piece includes a first A pole piece and a first B pole piece, and the first A pole piece is electrically connected to the first A pole ear. One end of the first B pole piece extends outward to form a first B pole tab, and the first A pole tab and the first B pole tab are electrically connected. There is at least one first A pole piece in the battery cell; The first pole piece includes a first current collector and a first active material layer; The first A tab is welded to the first current collector, the first active material layer is coated on the surface of the first current collector and surrounds the portion of the first A tab located on the first current collector, and the ratio of the weld mark height of the first A tab to the thickness of the first A tab is 0-2; The first B tab is integrally formed with the first current collector and is located outside the first current collector, and the first active material layer is coated on the surface of the first current collector; The thickness of the first A tab is 10~500 ; The thickness of the first B tab is 6~20 ; The thickness of the first A tab is greater than the thickness of the first B tab.

2. The battery cell according to claim 1, characterized in that The first pole pieces are stacked in sequence in the thickness direction of the battery cell, and the number of the first pole pieces is N. The i-th first pole piece in the thickness direction of the battery cell is the first A pole piece, wherein 30%≤i / N≤70%.

3. The battery cell according to claim 2, characterized in that Any surface of the first A tab is electrically connected to at most 50 of the first B tabs.

4. The battery cell according to claim 1, characterized in that The second pole piece includes a second A pole piece and a second B pole piece, the second A pole piece is electrically connected to the second A pole tab, one end of the second A pole piece extends outward to form a second B pole tab, and the second A pole tab and the second B pole tab are electrically connected; The second pole pieces are stacked sequentially in the thickness direction of the battery cell, and the number of the second pole pieces is M. The k-th second pole piece in the thickness direction of the battery cell is the second A pole piece, wherein 30%≤k / M≤70%.

5. The battery cell according to claim 4, characterized in that: Any surface of the second A-tab is electrically connected to at most 50 of the second B-tabs.

6. The battery cell according to claim 1, characterized in that The length of the first A tab is 5~200 mm, and the width of the first A tab is 2~50 mm; the length of the first B tab is 5~200 mm, and the width of the first B tab is 2~50 mm.

7. The battery cell according to claim 5, characterized in that The second pole piece includes a second current collector and a second active material layer; The second A tab is welded to the second current collector, and the second active material layer is coated on the second current collector. and surrounds the portion of the second A tab located on the second current collector, wherein the ratio of the weld print height of the second A tab to the thickness of the second A tab is 0-2; The second B tab is integrally formed with the second current collector and is located outside the second current collector, and the second active material layer is coated on the surface of the second current collector.

8. The battery cell according to claim 7, characterized in that: The thickness of the second A tab is 10~500 , the length of the second A-pole ear is 5~200㎜, and the width of the second A-pole ear is 2~50㎜; The thickness of the second B tab is 4 to 20 mm. , the length of the second B tab is 5~200㎜, and the width of the second B tab is 2~50㎜.

9. A lithium-ion battery, characterized in that: The invention comprises a battery casing, an electrolyte and the battery cell according to any one of claims 1 to 8.

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