Battery cells, secondary batteries, and power consumption devices

Abstract

The present invention discloses a battery cell, a secondary battery, and a power consumption device. The battery cell includes a plurality of electrode pieces, each electrode piece including a current collector and an active material coating layer, each electrode piece including a first region covered by the active material coating layer and a second region not covered by the active material coating layer, the first region being provided with a clearance notch, and the second region forming a tab of the battery cell, and in a plurality of electrode pieces arranged in a stack, for two adjacent electrode pieces, the first region of one electrode piece is provided with a clearance notch to expose the second region of the other electrode piece, the width of the electrode piece is W mm, and the area of ​​the clearance notch is S 1 mm 2 Therefore, the area of ​​the second region is S2mm². 2 The thickness of the battery cell is H, and if H > 7mm, then S1 + S2

Description

[Technical Field]

[0001] This invention relates to the field of battery technology, and more particularly to battery cells, secondary batteries, and power consumption devices. [Background technology]

[0002] A stacked battery cell is constructed by stacking multiple positive and negative current collector units using stacking technology. Current can flow sequentially through each current collector unit. In the stacking process, separators are used to provide insulation and connection between each current collector, ensuring that they work together to stably supply electrical energy. The stacked structure means that the battery can operate as a multi-tab battery, resulting in lower resistance, which reduces the heat generated during charging and discharging, and thus extends the battery's lifespan.

[0003] In a multi-tab type stacked battery cell, it is necessary to converge and cut multiple layers of uncoated foil in one direction to form a group of tabs, and then connect them to separate tab connecting pieces. The design of such a tab structure is related to the electrode assembly and Exterior A large gap exists between them, leading to a decrease in space utilization. [Overview of the project] [Problems that the invention aims to solve]

[0004] The embodiments of the present invention aim to provide a current collector, electrode assembly, battery cell, secondary battery, and power consumption device in order to solve the technical problem of low space utilization rate of stacked battery cells in the prior art. [Means for solving the problem]

[0005] To solve the technical problems of the present invention, the embodiments employ the following technical means.

[0006] As a first aspect of the present invention, the present invention discloses a laminated battery cell including electrode sheets, the electrode sheet includes a current collector and an active material coating layer, the electrode sheet includes a first region coated with the active material coating layer and a second region not coated with the active material coating layer, the first region is provided with an avoiding notch, the avoiding notch is for avoiding the second region of the adjacent current collector, the second region forms a tab of the current collector, among the plurality of laminated electrode sheets, for two adjacent electrode sheets, the first region of one electrode sheet is provided with an avoiding notch for exposing the second region of the other electrode sheet, the width of the electrode sheet is W mm, and the area of the avoiding notch is S1 mm 2 , and the area of the second region is S2 mm 2 , the thickness of the battery cell is H, when H>7 mm, S1+S2<A*W is satisfied, and A is 3.6 mm, or when H≦7 mm, S1+S2<B*W is satisfied, and B is 1.6 mm.

[0007] In this way, after the bare cells are laminated and formed, the tabs are accommodated in the main body region of the bare cell, so there is no need to arrange multi-tab relay welding outside the main body region at the head of the bare cell, and the space utilization rate can be improved. At the same time, by setting the maximum value of S1+S2 to 3.6W, it is ensured that the energy density of the battery cell is increased as a whole.

[0008] In one or more of the preferred embodiments described above, H≦7 mm, S1+S2<C*W is satisfied, and C is 1.0 mm. By implementing the structure for a battery cell with H≦7 mm, it can be ensured that the energy density is increased as a whole.

[0009] In one or more of the preferred embodiments described above, the area S1 of the avoiding notch is 5 mm 2 ~100 mm 2 , and the area S2 of the second region is 5 mm 2 ~100 mm 2 .

[0010] In one or more of the preferred embodiments described above, the area S1 of the avoiding notch is 10 mm 2 ~60 mm2 and the area S2 of the second region is 10 mm 2 to 60 mm 2 .

[0011] In one or more of the preferred embodiments described above, the electrode piece has a plurality of corners, the avoidance notch is provided at one corner of the electrode piece, and the second region is located at another corner of the electrode piece. By providing the avoidance notch and the second region at different corners of the electrode piece, the portion located at the corner of the current collector is caused to function as a tab, the gap between the electrode assembly and the outer package of the battery cell is reduced, and the energy density is improved.

[0012] In one or more of the preferred embodiments described above, the electrode piece is rectangular, and has a first side and a second side that are parallel to each other, a third side perpendicular to the first side, and a fourth side perpendicular to the second side. The avoidance notch is located at a first corner formed by the first side and the third side, and the second region is located at a second corner formed by the first side and the fourth side.

[0013] In one or more of the preferred embodiments described above, the current collector has a first direction parallel to the third side and a second direction parallel to the first side. The second region has a maximum dimension in the first direction of 1 mm to 15 mm, and a maximum dimension in the second direction of 1 mm to 15 mm. In the first direction, the distance between one end of the first side adjacent to the third side and the third side is 1 mm to 15 mm, and in the second direction, the distance between one end of the third side adjacent to the first side and the first side is 1 mm to 15 mm. In this way, by limiting the dimension of the tab within a reasonable range, it is possible to prevent the energy density of the battery cell from being reduced due to an excessively large tab dimension, and also prevent the electrical connectivity from being deteriorated due to an excessively small tab dimension.

[0014] In one or more of the above preferred embodiments, the second region has a maximum dimension of 3 mm to 10 mm in the first direction and a maximum dimension of 3 mm to 10 mm in the second direction, the distance between the end of the first side adjacent to the third side and the third side in the first direction is 3 mm to 10 mm, and the distance between the end of the third side adjacent to the first side and the first side in the second direction is 3 mm to 10 mm.

[0015] In one or more of the above preferred embodiments, both the avoidance notch and the second region are formed as polygons, and the number of line segments constituting the polygon is 3 to 8.

[0016] In one or more of the above preferred embodiments, the battery cell further includes an electrode assembly. Electrode assembly It includes a plurality of stacked anode pieces, a plurality of cathode pieces, and a separator located between the plurality of anode pieces and cathode pieces, wherein each anode piece is formed by coating the current collector with an anode active material, and when observed along the thickness direction of the electrode assembly, the tab of the anode piece is located in a first position and the avoidance notch provided on the anode piece is located in a second position, and each cathode piece is formed by coating the current collector with a cathode active material, and when observed along the thickness direction of the electrode assembly, the tab of the cathode piece is located in a second position The first position is located in the second position, and the avoidance notch provided in the cathode piece is located in the first position. When observing the separator along the thickness direction of the electrode assembly, the separator is provided with avoidance notches in both the first and second positions, and the multiple anode pieces and multiple cathode pieces are stacked, the separator is located between the anode pieces and cathode pieces, and multiple tabs located in the same position form a tab group, and in a tab group, at least a portion of the area between any two adjacent tabs is in contact with each other and forms an electrical connection.

[0017] In this way, after the positive electrode piece and the negative electrode piece are laminated to form a bare cell, the tabs are accommodated in the main body region of the bare cell, so there is no need to arrange multi-tab relay welding outside the head main body region of the bare cell, and the space utilization rate can be improved. In addition, during mechanical abuse, the tab group formed by converging the tabs is less susceptible to impact, shaking and twisting, so safety risks such as short circuits between the tabs and the current collector of the bare cell can be avoided.

[0018] In one or more of the preferred embodiments described above, the tab group is formed by a plurality of tabs located at the same position being inclined along the direction toward the thickness center of the electrode assembly, and the thickness center is selected from any one point in the intermediate region away from the surfaces on both sides of the electrode assembly in the thickness direction of the electrode assembly.

[0019] In one or more of the preferred embodiments described above, in the thickness direction, the distance between the tab group and the surface on one side of the electrode assembly is 0.3T to 0.7T, where T is the thickness of the electrode assembly.

[0020] In one or more of the preferred embodiments described above, for any one tab in the tab group, the angle between the tab and the surface of the current collector of the electrode piece where the tab is located is greater than 90°.

[0021] In this way, it is possible to avoid that the edge of the tab warps outward due to the deviation tolerance between adjacent tabs, the close contact with the adjacent tab is reduced, and the conductivity of the tab group is affected. On the other hand, if the preset angle a is set to be greater than 90°, two adjacent tabs will be parallel along the converging direction, thereby improving the mutual adhesion, reducing the resistance of the tab group, and improving the charge and discharge efficiency.

[0022] As a second aspect of the present invention, the present invention further discloses another battery cell, the battery cell includes the above electrode assembly, an exterior body for accommodating the electrode assembly, and at least two tab connecting pieces, wherein one tab connecting piece is electrically connected to one tab group of the electrode assembly, one end of the tab connecting piece is electrically connected to the tab group, and the other end extends to the outside of the exterior body to form an electric energy transmission path.

[0023] In one or more of the preferred embodiments described above, the tab connecting piece is provided at any one position selected from the group consisting of an upper surface of the tab group in the thickness direction, a lower surface of the tab group in the thickness direction, and a position between any two adjacent tabs inside the tab group.

[0024] As a third aspect of the present invention, the present invention discloses a secondary battery, the secondary battery includes a battery case and the battery cell described above, and the battery cell is accommodated in the battery case.

[0025] As a fourth aspect of the present invention, the present invention discloses a power consumption device, and the power consumption device is provided with the secondary battery described above.

[0026] Further aspects and advantages of the embodiments of the present invention will be partially described in the following, shown, or explained through the implementation of the embodiments of the present invention. [Brief Description of the Drawings]

[0027] One or more embodiments are exemplarily described with reference to the corresponding accompanying drawings, and these exemplary descriptions do not limit the embodiments. In the accompanying drawings, elements marked with the same reference numerals indicate similar elements. Unless otherwise specified, the accompanying drawings do not constitute a limitation of scale.

[0028] [Figure 1] FIG. 1 is a schematic diagram showing the structure of an electrode sheet in an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of an electrode sheet in an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram showing the structure of an electrode assembly in an embodiment of the present invention. [Figure 4] Figure 4 is an assembly diagram of an electrode assembly in an embodiment of the present invention. [Figure 5] Figure 5 is a schematic perspective view of the structure of the electrode assembly in an embodiment of the present invention. [Figure 6] Figure 6 is a plan view of an electrode assembly in an embodiment of the present invention. [Figure 7] Figure 7 is a cross-sectional view of the CC in Figure 6. [Figure 8] Figure 8 is a schematic diagram of a partial structure of a battery cell in an embodiment of the present invention. [Modes for carrying out the invention]

[0029] The present invention will be described in more detail below with reference to the drawings and specific embodiments in order to understand the present invention. When an element is described as being "fixed" to another element, that element may be directly on top of the other element, or one or more intervening elements may be present between them. When an element is described as being "connected" to another element, that element may be directly connected to the other element, or one or more intervening elements may be present between them. The orientations or positional relationships indicated by terms such as "up," "down," "inside," "outside," "vertical," and "horizontal" used herein are based on the orientations or positional relationships shown in the drawings and are merely for the purpose of facilitating and simplifying the explanation of the present invention. They do not require that the indicated or implied device or element has a specific orientation, or is configured and operated in a specific orientation, and should not be understood as limiting the present invention. Furthermore, terms such as "first," "second," etc., are merely for the purpose of explaining the purpose and should not be understood as indicating or implying relative importance. Similar terms such as “includes” or “equipment” mean that the element or article appearing before it encompasses the elements or articles and their equivalents listed thereafter, and do not exclude other elements or articles. Similar terms such as “connection” or “linking” are not limited to physical or mechanical connections, but may also include electrical connections, whether direct or indirect. Unless otherwise specified, features such as “parallel,” “perpendicular,” and “identical” as used in embodiments of the present invention include cases of “parallel,” “perpendicular,” and “identical” in the strict sense, and also include cases with certain errors such as “approximately parallel,” “approximately perpendicular,” and “approximately identical.” For example, “approximately” above means that the difference between the objects being compared is 10% or less or 5% or less of the average value of the objects being compared. In the following description of embodiments of the present invention, if the quantity of a part or element is not specifically specified, it can be understood that there may be one part or more, or at least one. “At least one” means one or more, and “more” means at least two.

[0030] Unless otherwise specified, the meanings of all technical and scientific terms used herein are the same as those generally understood by those skilled in the art. The terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit the invention. The terms “or / and” as used herein include any combination and all combinations of one or more of the related enumerated items.

[0031] Furthermore, the technical features of the different embodiments of the present invention described below can be combined with each other, provided they do not conflict with each other. Naturally, the embodiments described are only a part of the embodiments of the present invention, not all embodiments. All other embodiments that a person skilled in the art could obtain without creative effort based on the embodiments of the present invention described herein are all within the scope of the protection of the present invention.

[0032] The present invention discloses a stacked battery cell including an electrode piece 100. As shown in Figures 1 and 2, the electrode piece 100 includes a current collector 1 and an active material coating layer 2 coated on the current collector 1. The current collector 1 has a first region 11 covered with the active material coating layer 2 and a second region 12 not covered with the active material coating layer. The current collector 1 is a foil piece. The second region 12 is formed by removing a portion of the active material coating layer 2 from the surface of the electrode piece 100 by processing such as laser cleaning, solvent wiping, or adhesive stripping. The uncoated foil exposed in the second region 12 forms a tab 10 of the electrode piece 100. Here, the first region 11 is provided with a notch 3 for avoidance. The avoidance notches 3 are used to expose the second region 12 of adjacent electrode pieces 100 when multiple electrode pieces 100 are stacked and installed on top of each other, thereby facilitating contact between two adjacent tabs 10 of the same polarity. In other words, the avoidance notches 3 play an avoidance role when two spaced-apart tabs 10 are brought together.

[0033] Conventional stacked battery cell tabs are located outside the electrode assembly, making them susceptible to shock and vibration, thus posing a high safety risk. Furthermore, bundling uncoated foil in one direction increases the thickness of the bundled area, resulting in a larger occupied space.

[0034] In this embodiment, after the bare cells are laminated, the tabs 10 are housed within the main body area of ​​the bare cells, eliminating the need to install relay welds for the multi-tabs outside the main body area of ​​the bare cells and improving space utilization. Furthermore, when subjected to mechanical abuse, the cluster of tabs formed by the convergence of tabs is less susceptible to shock, vibration, and twisting, thus avoiding safety risks such as short circuits between the tabs and the current collectors of the bare cells.

[0035] In this embodiment, in the bare cell, one electrode piece 100 of opposite polarity is interposed between two adjacent electrode pieces 100 of the same polarity. The two tabs 10 of the same polarity are electrically connected by converging with each other through a bypass notch 3 in the intermediate opposite polarity electrode piece 100, forming a tab group.

[0036] Conventional stacked battery cells are formed by bundling and cutting multiple layers of uncoated foil tabs 10 in one direction to create a tab group. As the number of stacked tabs 100 increases, the thickness H of the battery cell increases, and consequently, the thickness of the tab group also increases. Thus, the gap K between the electrode assembly and the outer casing becomes larger with increasing battery cell thickness H, and the loss area S0 inside the outer casing also increases due to the gap K. The larger the loss area S0, the lower the proportion of active material involved in the electrochemical reaction, resulting in a lower energy density of the battery cell. Here, S0 = KW, where W is the width of the electrode piece 100.

[0037] Specifically, in the industry, when the battery cell thickness H > 7 mm, the gap K1 between the electrode assembly and the casing is 4 mm, and the corresponding loss area S0 = K1W. When H ≤ 7 mm, the gap K2 between the electrode assembly and the casing is 2 mm, and the corresponding loss area S0 = K2W.

[0038] In this embodiment, the uncoated foil in the second region 12 of the electrode piece 100 forms the electrode piece 100, and the battery cell manufactured using this electrode piece 100 can reduce the gap K3 between the electrode assembly and the outer casing to 0.4 mm, with a corresponding loss area S0 = (0.4 mm) * W.

[0039] Thus, compared to conventional technology, when the battery cell thickness H > 7 mm, the gain area of ​​the battery cell is △S1 = (K1 - K3)W = (3.6 mm) * W. When the battery cell thickness H ≤ 7 mm, the gain area of ​​the battery cell is △S1 = (K2 - K3)W = (1.6 mm) * W. Here, the gain area of ​​the battery cell is the area where the active material has increased, and the larger the gain area of ​​the battery cell, the greater the energy density of a battery cell of the same size.

[0040] However, in this embodiment, the electrode piece 100 has a first region 11 and a second region 12. First region 11 3 notches to avoid and the second area 12 some active material Remove This is necessary. This increases the loss area △S2, which reduces the space occupied by the active material. Here, △S2 = S1 + S2, where S1 is the area of ​​the avoidance notch 3 and S2 is the area of ​​the second region 12.

[0041] In order to ensure an increase in the energy density of the battery cell, in this embodiment, △S2 < △S1. This ensures that the maximum value of S1 + S2 is less than 3.6W, thereby ensuring an overall increase in the energy density of the thick battery cell with H > 7mm compared to the conventional technology. Therefore, in this embodiment, Avoidance notch 3 The total area of ​​the first region and the second region 12 is less than (3.6 mm) * W, that is, S1 + S2 <A*W、Aは3.6mmである。

[0042] Furthermore, in this embodiment, in order to increase the overall energy density of the thin battery cell with H ≤ 7 mm, Avoidance notch 3 The total area of ​​the first region and the second region 12 is less than (1.6 mm * W), that is, S1 + S2 <B*Wであり、Bは1.6mmである。

[0043] Furthermore, in order to increase the overall energy density of the thin battery cell with H≦7mm, in this embodiment, Avoidance notch 3 and the second region 12 is less than (1.0mm*W), that is, S1+S2<C*W, where C is defined as 1.0mm.

[0044] In this embodiment, since the avoiding notch 3 functions to expose the tab 10, when the area of the second region 12 is Avoidance notch 3 exceeded by the area of the avoiding notch, the excess portion in the second region 12 cannot be exposed, which has no practical significance and instead causes unnecessary loss of the active material. Conversely, Avoidance notch 3 when the area of the avoiding notch is larger than the area of the second region 12, not only the tab 10 is exposed, but also part of the active material is exposed from the avoiding notch 3, which similarly causes unnecessary loss of the active material. Therefore, in this embodiment, the area S2 of the avoiding notch 3 is equal to the area S1 of the second region 12, ensuring the maximization of the energy density of the battery cell.

[0045] The larger the overlapping area between the two tabs 10, the better the electrical connectivity of the two tabs 10. On the other hand, the larger the area of the avoiding notch 3 or the second region 12, the greater the loss in the energy density of the battery cell. When the area of the avoiding notch 3 is 5mm 2 or less, the area of the tab 10 is too small, which causes poor contact between two adjacent tabs 10 and affects the electrical connectivity of the tab group. When the area of the avoiding notch 3 is 100mm 2 or more, the overall energy density of the battery cell is too low. Therefore, in order to ensure excellent electrical connectivity when the tabs 10 are gathered to form a tab group, in this embodiment, the area of the avoiding notch 3 is set to 5~100mm 2 .

[0046] Considering the energy density of the battery cell, the area S1 of the avoiding notch 3 and the area S2 of the second region 12 are 5~60mm 2This is preferable. Within this range, the energy density is highest, the electrical connectivity between the multiple tabs 10 is strong, and safety requirements can be ensured.

[0047] Furthermore, the area S1 of the avoidance notch 3 and the area S2 of the second region 12 are 10-40 mm². 2 This is preferable. Within this range, the energy density and the electrical connectivity of tab 10 are further improved.

[0048] As shown in Figures 1 and 2, the electrode piece 100 has multiple corners, and the avoidance notch 3 and the second region 12 are located at two different corners, respectively. Specifically, as shown in Figure 1, this embodiment will be described below as an embodiment in which the electrode plate 100 is rectangular. The electrode plate 100 has a pair of parallel sides forming a rectangle, namely the first side 101 and the second side 102, and another pair of parallel sides, namely the third side 103 and the fourth side 104, where the first side edge 101 connects one end of the third side 103 and the fourth side 104, and the second side 102 connects the other end of the third side 103 and the fourth side 104. Here, the connection point between the first side 101 and the third side 103 forms the first corner, the connection point between the first side 101 and the fourth side 104 forms the second corner, the avoidance notch 3 is installed in the first corner, and the second region 12 is located in the second corner. In this embodiment, as shown in Figure 1, the specific structure of the avoidance notch 3 and the second region 12 is a chamfer provided in the first corner.

[0049] In this embodiment, the avoidance notch 3 and the chamfered hypotenuse of the second region 12 are polygons, and the number of sides is 3 to 8. In other words, the avoidance notch 3 and the chamfered hypotenuse of the second region 12 may consist of 3 to 8 line segments.

[0050] As shown in Figures 3 and 4, an embodiment of the present invention discloses an electrode assembly 4 formed by stacking the above electrode pieces 100. The electrode assembly 4 is provided with a plurality of anodes stacked together. Piece 41 and multiple cathodes Piece 42 and anode Piece 41 and cathode PieceIt includes a separator 43 located between 42 and 42.

[0051] Multiple anode pieces 41, cathode pieces 42, and separators 43 can be stacked as follows: (1) The anode piece 41, separator 43, cathode piece 42, and separator 43 are stacked in this order repeatedly. Or, (2) The cathode piece 42, separator 43, anode piece 41, and separator 43 are stacked in this order repeatedly. Or, (3) First, the separator 43 is heat-pressed onto both the upper and lower surfaces of the anode piece 41 to form a composite, and then the cathode piece 42 and anode piece 41 are stacked sequentially, and this stacking is repeated. Or, (4) First, the separator 43 is heat-pressed onto both the upper and lower surfaces of the cathode piece 42 to form a composite, and then the anode piece 41 and cathode piece 42 are stacked sequentially, and this stacking is repeated.

[0052] Specifically, as shown in Figure 2, the active material coating layer 2 applied to the surface of the current collector 1 includes an anode active material 21 and a cathode active material 22. As shown in Figure 4, the tab 10 further includes an anode tab 10a and a cathode tab 10b, depending on the polarity of the electrode piece 100. The avoidance notch 3 includes an anode avoidance notch 31 and a cathode avoidance notch 32 provided on the cathode piece 42, depending on the polarity of the tab 10 to be avoided. The anode avoidance notch 31 is used to avoid the anode tab 10a, and the cathode avoidance notch 32 is used to avoid the cathode tab 10b.

[0053] Each anode piece 41 is made by coating the current collector 1 with anode active material 21, and each cathode piece 42 is made by coating the current collector 1 with cathode active material 22. When observed along the thickness direction of the electrode assembly 4 (plan view), the anode tab 10a of the anode piece 41 is located at the first position 44, and the cathode avoidance notch 32 provided on the anode piece 41 is located at the second position 45. The cathode tab 10b of the cathode piece 42 is located at the second position 45, and the anode avoidance notch 31 provided on the cathode piece 42 is located at the first position 44. In other words, the avoidance notch 3 and the tab 10 are located at opposite positions on the anode piece 41 and the cathode sheet 42.

[0054] The separator 43 is provided with avoidance notches 3 at both the first position 44 and the second position 45. In other words, the separator 43 is provided with an anode avoidance notch 31 at the first position 44 and a cathode avoidance notch 32 at the second position 45. Thus, both the anode tab 10a and the anode avoidance notch 31 are located at the first position 44, and the cathode tab 10b The cathode avoidance notch 32 is located at the second position 45. Multiple tabs 10 at the same position form a tab group 13. Specifically, the anode tab 10a converges with adjacent anode tabs 10a through the separator film 43 and the cathode avoidance notch 31 of the cathode piece 42 to form an anode tab group 131 corresponding to the anode piece 41. The cathode tab 10b converges with adjacent cathode tabs 10b through the separator film 43 and the cathode avoidance notch 32 of the anode piece 41 to form a cathode tab group 132 corresponding to the anode piece 42.

[0055] In one tab group 13, at least a portion of the area between any two adjacent tabs 10 is in contact with each other, forming an electrical connection. In other words, in a tab group 13 corresponding to an anode piece 41, two adjacent anode tabs 10a are in contact and connected along the focusing direction.

[0056] figure 7 As shown, the tab group 13 is formed by multiple tabs 10 located at the same position being inclined toward the thickness center of the electrode assembly 4. Here, the thickness center is located in the intermediate region in the thickness direction of the electrode assembly 4, and this point is away from the outermost tabs 10 on both sides of the electrode assembly 4. In other words, the anode tab group 131 is formed by the anode tabs 10a located on both sides converging toward the anode tab 10a located in the center. The cathode tab group 132 is formed by the cathode tabs 10b located on both sides converging toward the cathode tab 10b located in the center.

[0057] figure 7 As shown, the distance d5 between the focused tab group 13 and the outermost tab 10 is 0.3T to 0.7T, where T is the thickness of the electrode assembly 4.

[0058] Furthermore, in this embodiment, as shown in Figure 7, a predetermined angle a is formed between one of the tabs 10 in the tab group 13 and the surface of the current collector of the electrode piece on which the tab is located, and this predetermined angle a is greater than 90°. This prevents the edges of the tabs 10 from curving outward due to misalignment tolerances between adjacent tabs 10, which would reduce contact with adjacent tabs 10 and affect the conductivity of the tab group 13. On the other hand, if the predetermined angle a is set greater than 90°, two adjacent tabs 10 become parallel along the focusing direction, thereby increasing their mutual contact, reducing the resistance of the tab group 13, and improving the charge and discharge efficiency.

[0059] Embodiments of the present invention further disclose a battery cell, as shown in Figures 5 and 6, which comprises an electrode assembly 4, an outer casing 5 for housing the electrode assembly 4, and at least two tab connectors 6, each tab connector 6 being electrically connected to one group of tabs 13 of the electrode assembly 4, forming an electrical energy transmission path. Specifically, as shown in Figure 8, an electrolyte is injected into the outer casing 5, and the electrode assembly 4 is encapsulated within the outer casing 5. One end of the tab connector 6 is located inside the outer casing 5 and is electrically connected to the group of tabs 13. Here, the tab connector 6 is electrically connected to the group of tabs 13 by laser welding or ultrasonic welding, and the position where the two are electrically connected may be the center of the group of tabs 13 or on both sides of the group of tabs 13. The tab connector 6 is provided with a sealant portion 60, which is located within the sealing region 50 of the outer casing 5, improving the sealing performance of the sealing region 50 and preventing leakage of the battery cell when it is dropped.

[0060] During actual manufacturing, the stacked battery cells undergo drop testing and tab connection testing. Piece It must pass the sealing test.

[0061] Here, (1) the drop test process is as follows: After fully charging the samples according to the specified test method, they were dropped onto a concrete slab from a height of 1m (1m for battery packs of 1000mAh or more, and 1.5m for batteries of 1000mAh or less or portable electronic products with a planned usage height of 1.0m or more). For cylindrical battery samples and button-type battery samples, a total of four drop tests were performed: once on each of the two end faces and twice on the cylindrical surface. For prismatic battery samples and soft-pack battery cell samples, a total of six tests were performed: once on each face. For battery packs, one charge-discharge cycle was performed after the test according to the specified charge-discharge method. of Do it again.

[0062] Acceptance Criteria: Batteries must not ignite or explode. Battery packs must not ignite, explode, or leak. Battery cells must pass inspection at a rate of ≥80%.

[0063] (2) Tab connection Piece Sealing test: During the actual manufacturing of battery cells, tab connections Piece The percentage P of the sealant portion 60 on 6 that is exposed from the sealed area 50 is collected.

[0064] Acceptance Criteria: If P ≤ 10%, the product is considered acceptable and meets the mass production requirements.

[0065] Area S1 of the avoidance notch 3 and area S of the second region 12 2 The dimensions of the tabs are affected, and the dimensions of tab 10 affect the relative position between the sealant portion 60 of the tab connector 6 and the sealing area 50. Therefore, the dimensions of tab 10 are related to the sealing performance of the battery cell. Specifically, if the dimensions of tab 10 are too small, the contact area between the tab group 13 and the tab connector 6 will be too small, leading to separation of the tab connector 6 and the tab group 13 during the drop test. This prevents the battery cell from being used normally and poses a risk of ignition or explosion due to a short circuit between the cathode and anode, affecting the pass rate of the drop test. At the same time, tab 1 0If the dimensions are too small, the position of the tab connector 6 shifts outward, increasing the proportion of the sealant portion 60 exposed from the sealing area 50, which destroys the sealing performance of the battery cell and lowers the pass rate of the sealing performance test. On the other hand, if the dimensions of the tab 10 are too large, the pass rate of the drop test improves significantly, and the proportion of the sealant portion 60 exposed from the sealing area 50 can also be reduced, but it can occupy space in the part involved in the electrochemical reaction, lowering the energy density of the battery cell.

[0066] Therefore, the dimensions of the tab 10 cannot be set so large as to reduce the energy density of the battery cell, nor can they be set so small as to affect the safety standards required for product drop tests and tests of the degree of fold-over insertion of the tab connecting piece 6. Accordingly, the inventors of the present invention conducted numerous experiments on the dimensions of the tab 10, and the experimental data is shown in Table 1 below.

[0067] [Table 1]

[0068] In this embodiment, the energy density level is a relative concept, representing the difference between the current sample's energy density and the optimal energy density.

[0069] Here, a higher energy density level indicates a greater difference between the two, representing a lower energy density in the corresponding sample. Conversely, a lower energy density level indicates an approach to the optimal energy density. If the energy density level is 10 or higher, there is a significant difference between the two, and the product can be evaluated as unacceptable. In other words, an energy density level of 1 to 9 is acceptable. Based on experimental data, the area S1 of the avoidance notch 3 and the area S2 of the second region are 5 to 100 mm². 2 If this is the case, the energy density level, drop pass rate, and sealing test failure rate all meet the criteria. S1 and S2 are 5-60 mm 2 If this is the case, the energy density of the battery cell is high. S1 and S2 are 10-40 mm 2In that case, the energy density, drop rate, and sealing performance tests are all at a high level.

[0070] Embodiments of the present invention further disclose a secondary battery and a power consumption device equipped with the secondary battery, the secondary battery comprising a battery case and the battery cells housed within the battery case.

[0071] The above embodiments are used to illustrate the technical means of the embodiments of the present invention and are not intended to limit the present invention. Based on the spirit of the present invention, combinations of the technical features in the above embodiments or different embodiments are also possible, the steps can be carried out in any order, and many other modifications exist to the different aspects of the present invention described above, but for the sake of brevity, they will not be described in detail. The present invention has been described in detail based on the embodiments described above, but those skilled in the art can modify the technical means described in each of the above embodiments or replace some of the technical features with equivalent ones, and these modifications or substitutions will not cause the essence of the corresponding technical means to deviate from the scope of the technical means of each embodiment of the present invention. [Explanation of Symbols]

[0072] 100 electrode pieces, 1 Current collector, 101 First side, 102 Second side, 103 Third side, 104 Fourth side Side, 10 tab, 10a anode tab, 10b cathode tab, 11 first region, 12 second region Region, 13 tab group, 131 anode tab group, 132 cathode tab group, 2 active material coating layer, 21 anode active material, 22 cathode active material, 3 Avoidance notch, 31 Anode avoidance notch, 32 Cathode avoidance notch, 4 electrode assembly, 41 anode piece, 42 cathode piece, 43 separator, 44 first place position, 45 2nd position, 5 exterior body, 50 sealing area, 6 tab connecting pieces, 60 sealant sections.

Claims

1. A battery cell comprising a plurality of electrode pieces arranged in a stack, The electrode piece includes a current collector and an active material coating layer. The electrode piece includes a first region covered with the active material coating layer and a second region not covered with the active material coating layer. The first region is provided with an avoidance notch, which is for avoiding a second region of the adjacent electrode piece, and the second region forms a tab of the battery cell. In the plurality of electrode pieces arranged in a stack, for two adjacent electrode pieces, the first region of one electrode piece is provided with the avoidance notch to expose the second region of the other electrode piece. The width of the electrode piece is W mm, and the area of ​​the avoidance notch is S1 mm. 2 The area of ​​the second region is S2 mm². 2 The thickness of the battery cell is H, If H > 7 mm, then S1 + S2 < A * W is satisfied, and A is 3.6 mm, or If H ≤ 7 mm, then S1 + S2 < B * W is satisfied, and B is 1.6 mm. A battery cell characterized by the following features.

2. H ≤ 7 mm, and S1 + S2 < C * W is satisfied, and C is 1.0 mm. A battery cell according to claim 1, characterized in that...

3. The area S1 of the aforementioned avoidance notch is 5 mm 2 ~100mm 2 The area S2 of the second region is 5 mm². 2 ~100mm 2 That is, A battery cell according to claim 1, characterized in that...

4. An area S1 of the avoidance notch is 5 mm 2 to 60 mm 2 , and an area S2 of the second region is 5 mm 2 to 60 mm 2 , A battery cell according to claim 1, characterized in that...

5. The area S1 of the aforementioned avoidance notch is 10 mm 2 ~40mm 2 The area S2 of the second region is 10 mm². 2 ~40mm 2 That is, A battery cell according to claim 1, characterized in that...

6. The electrode piece has multiple corners, The aforementioned avoidance notch is provided at one corner of the electrode piece, and the second region is located at the other corner of the electrode piece. A battery cell according to any one of claims 1 to 5, characterized in that

7. The electrode piece has a first side and a second side that are parallel to each other, a third side perpendicular to the first side, and a fourth side perpendicular to the second side. The avoidance notch is located at the first corner formed by the first side and the third side, and the second region is located at the second corner formed by the first side and the fourth side. The battery cell according to claim 6, characterized in that

8. The electrode piece has a first direction parallel to the third side and a second direction parallel to the first side. The second region has a maximum dimension of 1 mm to 15 mm in the first direction, and a maximum dimension of 1 mm to 15 mm in the second direction. In the first direction, the distance between the end of the first side adjacent to the third side and the third side is 1 mm to 15 mm, and in the second direction, the distance between the end of the third side adjacent to the first side and the first side is 1 mm to 15 mm. The battery cell according to claim 7, characterized in that

9. The second region has a maximum dimension of 3 mm to 10 mm in the first direction, and a maximum dimension of 3 mm to 10 mm in the second direction. In the first direction, the distance between the end of the first side adjacent to the third side and the third side is 3 mm to 10 mm, and in the second direction, the distance between the end of the third side adjacent to the first side and the first side is 3 mm to 10 mm. The battery cell according to claim 8, characterized in that

10. The aforementioned avoidance notch and the second region are both formed in the shape of a polygon. The number of line segments constituting the aforementioned polygon is between 3 and 8. A battery cell according to any one of claims 1 to 5, characterized in that

11. The electrode assembly further includes a plurality of stacked anode pieces, a plurality of cathode pieces, and a separator located between the anode pieces and the cathode pieces. With respect to a plurality of anode pieces, each anode piece is formed by coating the current collector with an anode active material, and when observed along the thickness direction of the electrode assembly, the tab of the anode piece is located in a first position, and the avoidance notch provided in the anode piece is located in a second position. With respect to the multiple cathode pieces, each cathode piece is formed by coating the current collector with a cathode active material, and when observed along the thickness direction of the electrode assembly, the tab of the cathode piece is located at the second position, and the avoidance notch provided in the cathode piece is located at the first position. When the separator is observed along the thickness direction of the electrode assembly, it is found that the separator is provided with avoidance notches at the first position and the second position, respectively. The plurality of anode pieces and the plurality of cathode pieces are arranged in a stack, the separator is located between the anode pieces and the cathode pieces, the plurality of tabs located at the same position form a tab group, and in one tab group, at least a portion of the area between any two adjacent tabs is in contact with each other and forms an electrical connection. A battery cell according to any one of claims 1 to 5, characterized in that

12. The group of tabs is formed by multiple tabs located at the same position being inclined along the direction toward the center of the thickness of the electrode assembly. The thickness center is selected from any one point in the intermediate region of the electrode assembly, away from both sides of the electrode assembly, in the thickness direction of the electrode assembly. The battery cell according to claim 11, characterized in that

13. In the thickness direction, the distance between the tab group and one surface of the electrode assembly is 0.3T to 0.7T, where T is the thickness of the electrode assembly. The battery cell according to claim 11, characterized in that

14. For any one tab among the group of tabs, the angle between the tab and the surface of the current collector of the electrode piece on which the tab is located is greater than 90°. The battery cell according to claim 11, characterized in that

15. An outer casing housing the electrode assembly, It further includes at least two tab connecting pieces, One of the tab connecting pieces is electrically connected to one group of tabs of the electrode assembly, and one end of the tab connecting piece is electrically connected to the group of tabs, while the other end extends to the outside of the outer casing, forming an electrical energy transmission path. The battery cell according to claim 11, characterized in that

16. The aforementioned tab connecting piece is The upper surface in the thickness direction of the tab group, The lower surface in the thickness direction of the tab group, and Between any two adjacent tabs within the aforementioned group of tabs, It is installed in one of the following locations: The battery cell according to claim 15, characterized in that

17. It is a secondary battery, The battery case comprises a battery cell according to any one of claims 1 to 16, wherein the battery cell is housed within the battery case. A secondary battery characterized by the following features.

18. A power consumption device comprising a secondary battery as described in claim 17, A power consumption device characterized by the following features.

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