Winding type battery cell and electric equipment

Abstract

The utility model relates to the field of lithium batteries, and discloses a winding type battery cell and electric equipment.The battery cell comprises a first pole piece, a diaphragm and a second pole piece which are wound in a stacked mode, and the first pole piece comprises a current collector; the active material layer is positioned on the first surface and / or the second surface of the current collector; the first surface and the second surface are two opposite surfaces in the first direction; concave parts are distributed on at least one active material layer, extend from the first end of the first pole piece to the second end far away from the first end in the second direction, and are correspondingly positioned on the outermost ring of the winding type battery cell; the first end is a winding ending end, and the second end is a winding starting end. When the first pole piece is extended, the concave part can play an extension compensation role, the extension stops in the concave part, the width of the concave part is narrowed to replace the extension of the first pole piece, so that the aim of inhibiting the extension of the edge of the first pole piece is fulfilled, and the concave part is at least positioned on the outermost ring of the battery cell, so that the influence of the extension of the first pole piece on the membrane shell can be reduced; and the safety performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium batteries, in particular to a wound cell and an electric device. BACKGROUND

[0002] Lithium ion battery is a kind of rechargeable battery, which works by moving lithium ions between the positive and negative electrodes. Lithium ion batteries can be used as power supply for electronic consumer products, and the demand for high energy of the battery is an inevitable trend. For example, for high energy density negative electrode sheet, it has the attribute of high ductility after rolling, and during the cell pressurization process, the positive electrode sheet will also be ductile, which will cause the edge of the positive electrode sheet to interfere with the film shell during the later cycle process of the cell, resulting in the problem of film shell rupture and potential safety hazard of the cell.

[0003] Therefore, how to solve the above technical problems should be the focus of attention of those skilled in the art. CONTENT OF THE UTILITY MODEL

[0004] The purpose of the present application is to provide a wound cell and an electric device to reduce the situation of corner breakage and improve the safety performance of the cell.

[0005] To solve the above technical problems, the present application provides a wound cell, which comprises a first electrode sheet, a separator and a second electrode sheet stacked and wound, the first electrode sheet comprising:

[0006] a current collector;

[0007] an active material layer located on the first surface and / or the second surface of the current collector; the first surface and the second surface are two opposite surfaces in the first direction;

[0008] at least one layer of the active material layer is distributed with a recess, the recess is distributed from the first end of the first electrode sheet to the second end away from the first end in the second direction, the recess corresponds to the outermost circle of the wound cell; the second direction is perpendicular to the first direction, the first end is the end of winding, and the second end is the starting end of winding.

[0009] Optionally, the recess comprises a groove, and the active material layer is distributed with the groove.

[0010] Optionally, in the first direction, the depth d of the groove ranges from (20%D±7) to (80%D±7), D is the thickness of the active material layer, and the depth d of the groove is less than the thickness of the active material layer.

[0011] Optionally, in the second direction, the distance L1 between one end of the groove close to the first end and the edge of the active material layer close to the first end ranges from 0 to 6 mm.

[0012] Optionally, the active material layers on the first surface and the second surface of the current collector are both distributed with the recesses, and the projections of the recesses distributed on the active material layer on the first surface of the current collector and the projections of the recesses distributed on the active material layer on the second surface of the current collector are staggered with each other.

[0013] Optionally, the recesses comprise slits, and in the first direction, at least one of the active material layers and the current collector is distributed with the slits.

[0014] Optionally, the empty current collector area of the current collector is also distributed with the slits; and the empty current collector area is located at the first end of the first tab.

[0015] Optionally, in the second direction, the distance L2 between one end of the slits close to the first end and the edge of the active material layer close to the first end ranges from 0 to 10 mm.

[0016] Optionally, the number N of the recesses ranges from 1 to 10; and / or,

[0017] The width W2 of the recesses in the third direction perpendicular to the first direction and the second direction ranges from 100 μm to 400 μm.

[0018] Optionally, when the number of the recesses is at least two, all the recesses are distributed along the third direction perpendicular to the first direction and the second direction.

[0019] In the third direction, the distance W1 between the edges of the recesses on both sides and the edges of the active material layer closest to the recesses ranges from 9 mm to 15 mm.

[0020] Optionally, the first tab is a positive tab, and the second tab is a negative tab.

[0021] Optionally, one end of the recess close to the second end extends to the first outermost circular arc of the wound battery cell.

[0022] Optionally, the length L of the recess in the second direction is L = 2a + 2*n*b, a is the width of the wound battery cell, b is the thickness of the wound battery cell, and n ranges from 1.2 to 2.

[0023] Optionally, one end of the recess close to the second end extends to the second outermost circular arc of the wound battery cell.

[0024] The application further provides a use electric device comprising the wound battery cell as described in any of the above.

[0025] The winding type battery provided in the application comprises: a first pole piece, a diaphragm and a second pole piece which are laminated and wound, the first pole piece comprises: a current collector; an active material layer on the first surface and / or the second surface of the current collector; the first surface and the second surface are two surfaces opposite in a first direction; at least one layer of the active material layer is distributed with a recess, the recess is distributed from a first end of the first pole piece to a second end away from the first end in a second direction, the recess corresponds to the outermost circle of the winding type battery; the second direction is perpendicular to the first direction, the first end is a winding end, and the second end is a winding start end.

[0026] It can be seen that the first pole piece of the winding type battery provided in the application is distributed with at least one layer of active material layer, and the recess extends from the first end of the first pole piece to the second end away from the first end. When the first pole piece is extended, the recess can play a compensatory role of the extension of the first pole piece, the first pole piece is stopped in the recess, the width of the recess is narrowed, and the extension of the first pole piece is replaced, so that the purpose of inhibiting the extension of the edge of the first pole piece is achieved. Since the recess is located at the outermost circle of the winding type battery, the influence of the extension of the first pole piece on the diaphragm shell can be reduced, and the safety performance is improved.

[0027] In addition, the application also provides a power consumption device with the above advantages. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 A cross-sectional view of a winding type battery provided by an embodiment of the application;

[0030] Figure 2 A front view of a first pole piece provided by an embodiment of the application;

[0031] Figure 3 A top view of a first pole piece provided by an embodiment of the application Figure 1 ;

[0032] Figure 4 A top view of a first pole piece provided by an embodiment of the application Figure 2 ;

[0033] Figure 5 A top view of a first pole piece provided by an embodiment of the application Figure 3 ;

[0034] Figure 6 A corresponding relationship diagram of a first pole piece and a second pole piece in a winding type battery cell provided by an embodiment of the present application is shown in the figure.

[0035] Figure 7 A side view of a first pole piece provided by an embodiment of the present application is shown in the figure. Figure 1 ;

[0036] Figure 8 A top view of a first pole piece provided by an embodiment of the present application is shown in the figure. Figure 4 ;

[0037] Figure 9 A side view of a first pole piece provided by an embodiment of the present application is shown in the figure. Figure 2 ;

[0038] Figure 10 A top view of a first pole piece provided by an embodiment of the present application is shown in the figure. Figure 5 ;

[0039] Figure 11 A top view of a first pole piece provided by an embodiment of the present application is shown in the figure. Figure 6 ;

[0040] In the figure, 1 is a current collector, 2 is an active material layer, 3 is a recess, 11 is an empty current collector area, 100 is a second pole piece, 200 is a first pole piece, 300 is a diaphragm, and 400 is a pole lug. DETAILED DESCRIPTION

[0041] In order to make the person skilled in the art better understand the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor are within the scope of protection of the present application.

[0042] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0043] As described in the background section, in a battery cell, when one pole piece has high ductility, the pole piece of opposite polarity also has ductility, the pole piece edge will interfere with the film shell, causing the angle position to break, and further causing the battery cell safety problem.

[0044] Therefore, the present application provides a winding type battery cell, please refer toFigures 1 to 5 The winding stack can include a first electrode sheet 200, a separator 300, and a second electrode sheet 100, the first electrode sheet 200 including:

[0045] a current collector 1;

[0046] an active material layer 2 located on a first surface and / or a second surface of the current collector 1; the first surface and the second surface are two opposite surfaces in a first direction Z;

[0047] The at least one active material layer 2 is distributed with recesses 3, the recesses 3 being distributed from a first end A of the first electrode sheet 200 to a second end B away from the first end A in a second direction Y, the recesses 3 corresponding to the outermost circle of the winding type battery cell; the second direction Y is perpendicular to the first direction Z, the first end is a winding end, and the second end is a winding start end.

[0048] The winding type battery cell further includes a tab 400 electrically connected to the first electrode sheet 200 and the second electrode sheet 100, respectively.

[0049] The winding type battery cell in the present application can be all winding core structures in a soft package battery cell.

[0050] It should be noted that the type of the first electrode sheet 200 is not limited in the present embodiment and is determined as appropriate.

[0051] As an implementable manner, the first electrode sheet 200 is a positive electrode sheet, and the second electrode sheet 100 is a negative electrode sheet. When the first electrode sheet 200 is a positive electrode sheet, the current collector 1 is a positive electrode current collector, and the active material layer 2 is a positive electrode active material layer.

[0052] As another implementable manner, the first electrode sheet 200 is a negative electrode sheet, and the second electrode sheet 100 is a positive electrode sheet. When the first electrode sheet 200 is a negative electrode sheet, the current collector 1 is a negative electrode current collector, and the active material layer 2 is a negative electrode active material layer.

[0053] The positive electrode current collector can be an aluminum foil, and the material of the positive electrode active material layer can be lithium cobaltate, lithium manganate, lithium nickelate, lithium iron phosphate, lithium nickel cobalt manganate, lithium nickel cobalt aluminum phosphate, lithium manganese iron phosphate, etc., which is not limited in the present embodiment.

[0054] The negative electrode current collector can be a copper foil, and the material of the negative electrode active material layer can be a carbon material, such as natural graphite, artificial graphite, modified graphite, soft carbon, hard carbon, etc., or can also be a non-carbon material, such as a tin-based material, a silicon-based material, etc., which is not limited in the present embodiment.

[0055] The first direction Z is the thickness direction of the first electrode sheet 200, the second direction Y is the length direction of the first electrode sheet 200, and the third direction X is the width direction of the first electrode sheet 200, and the first direction Z, the second direction Y, and the third direction X are perpendicular to each other.

[0056] When the first electrode sheet 200 is made into a wound type battery cell, the side of the first electrode sheet 200 corresponding to the side of the second electrode sheet 100 with opposite polarity is provided with the active material layer 2, that is, when the first electrode sheet 200 is located at the innermost layer or the outermost layer of the wound type battery cell, the first surface or the second surface of the current collector 1 is provided with the active material layer 2, and when the first electrode sheet 200 is located at the middle position, the first surface and the second surface of the current collector 1 are both provided with the active material layer 2.

[0057] For example, when the first electrode sheet 200 in the present embodiment is a positive electrode sheet, there is only one layer of active material layer 2 on the positive electrode sheet when the positive electrode sheet is at the end of the wound type battery cell, and there are two layers of active material layer 2 on the positive electrode sheet when the positive electrode sheet is at the end of the wound type battery cell.

[0058] It should be noted that the width of the recess 3 in the present embodiment is not limited and can be set as desired.

[0059] As an implementable manner, the width W2 of the recess 3 in the third direction X is in the range of 5 μm≤W2≤1000 μm. The third direction X is perpendicular to the first direction Z and the second direction Y.

[0060] For example, the width W2 of the recess 3 can be 5 μm, 20 μm, 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, etc.

[0061] The width W2 of the recess 3 in the third direction X is preferably in the range of 100 μm≤W2≤400 μm. If the width W2 of the recess 3 is too narrow, it cannot compensate for the extension of the first electrode sheet 200 well, and if the width of the recess 3 is too wide, too much active material layer 2 is removed, which affects the energy density of the battery cell.

[0062] It should be noted that the number of recesses 3 on the first electrode sheet 200 in the present embodiment is not limited and can be set as desired. As an implementable manner, the number N of recesses 3 can be in the range of 1≤N≤10. For example, the number of recesses 3 can be 1, as shown in FIG. 2A; the number of recesses 3 can be 2, as shown in FIG. 2B; the number of recesses 3 can be 3, as shown in FIG. 2C; and the number of recesses 3 can also be 4, 6, 8, 10, etc. Figure 3 Figure 2 Figure 4

[0063] If the number of recesses 3 is too large, on the one hand, it will cause too much active material layer 2 to be removed, which affects the energy density of the wound type battery cell; on the other hand, it will also cause damage to the surface of the wound type battery cell, which is prone to powder falling. ​​​

[0064] The number of the recesses 3 is selected depending on the height of the wound cell, the extension of the negative tab, and the compensation effect is better as closer to the edge of the positive tab, and the optimal number is 2. If the wound cell is high (> 140 mm) and the extension of the negative tab is large (> 700 μm), the number of the recesses 3 can be increased.

[0065] It should be further pointed out that the position of the recess 3 is not limited in the embodiment, and can be set by itself.

[0066] For example, when the number of the recesses 3 is 1, in the third direction X, the recess 3 can be located in the middle of the active material layer 2, as shown in FIG. 2A, and of course can be biased to either edge. Figure 3

[0067] When the number of the recesses 3 is at least two, all the recesses 3 are distributed along the third direction X, and as an implementable manner, all the recesses 3 can be uniformly distributed along the third direction X.

[0068] As another implementable manner, when the number of the recesses 3 is at least two, all the recesses 3 are distributed along the third direction X, and the third direction X is perpendicular to the first direction Z; in the third direction X, the distance W1 between the recesses 3 on both sides and the edge of the active material layer 2 closest to them ranges from 9 mm to 15 mm.

[0069] As shown in FIG. 2B and FIG. 2C, in the third direction X, the recesses 3 on both sides, i.e., the uppermost recess 3 and the lowermost recess 3, the distance between the recesses 3 on both sides and the edge of the active material layer 2 closest to them, i.e., the distance between the uppermost recess 3 and the upper edge of the first tab 200, and the distance between the lowermost recess 3 and the lower edge of the first tab 200. Figure 2 Figure 4

[0070] For example, the distance W1 between the recesses 3 on both sides and the edge of the active material layer 2 closest to them can be 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, etc.

[0071] The smaller the distance W1 between the recesses 3 on both sides and the edge of the active material layer 2 closest to them, the better, but if it is too small, the edge area of the first tab 200 is prone to cracking and powdering, so the distance W1 is controlled to be 9 mm to 15 mm.

[0072] ​​​The negative plate will expand in all directions during pressure formation, and the expansion in the slitting width direction is called negative full charge elongation. The elongation of the negative plate will drive the positive plate to elongate through the separator. Since the positive plate is the outermost circle of the wound cell in the mainstream design, it will directly contact the aluminum plastic film shell. At the same time, due to the hard characteristics of the positive plate, when the positive plate elongates too much, there is a risk of shell damage. The present application focuses on inhibiting excessive elongation of the positive plate. Therefore, the width and number of recesses 3 are based on the full charge elongation of the negative plate (measurement method: full charge negative plate width-negative plate slitting width median or negative plate empty current collector area width).

[0073] The first pole piece 200 of the wound cell of the present embodiment has at least one active material layer 2 distributed with recesses 3 extending from the first end A to the second end B of the first pole piece 200. When the first pole piece 200 elongates, the recesses 3 can play a compensatory role in the elongation of the first pole piece 200. The first pole piece 200 elongates in the recess 3, and the width of the recess 3 narrows, replacing the elongation of the first pole piece 200, thereby achieving the purpose of inhibiting the edge elongation of the pole piece. And because the recess 3 is located in the outermost circle of the wound cell, the influence of the first pole piece 200 elongation on the shell can be reduced, and the safety performance can be improved.

[0074] The recess 3 corresponds to the outermost circle of the cell, and when the first pole piece 200 elongates, the recess 3 can play a compensatory role in the elongation. The specific position of the recess 3 in the present embodiment is not limited and can be set as needed.

[0075] In an embodiment of the present application, one end of the recess 3 near the second end extends at least to the first arc on the outermost side of the wound cell, that is, the recess 3 extends at least through the first arc on the outermost side of the wound cell.

[0076] The arc of the wound cell corresponds to the position of the four corners of the shell, which is the point of corner cracking. The arc position directly acts on the thinnest corner of the shell, which can improve the cracking condition of the corner of the shell.

[0077] As an implementable way, one end of the recess 3 near the second end B extends to the second arc on the outermost side of the wound cell, that is, one end of the recess 3 near the second end extends through the first two arcs on the outermost side of the wound cell, that is, the recess 3 is distributed in the outermost circle of the wound cell, which can maximize the improvement of the cracking problem caused by the elongation of the first pole piece 200, and further improve the safety of the cell.

[0078] As Figures 2 to 4As shown, the dashed line on the first tab 200 extending in the third direction X is the position of the circular arc when winding, and the dashed line closest to the first end A (the first dashed line on the right) corresponds to the outermost first circular arc of the wound cell. In the second direction Y, the one end of the recess 3 close to the second end B is at least flush with the outermost first circular arc of the wound cell, that is, the one end of the recess 3 close to the second end B is at least flush with the first dashed line on the right (the outermost first circular arc of the cell). Figures 2 to 4 In some embodiments, the one end of the recess 3 close to the second end B is flush with the second dashed line on the right, that is, the one end of the recess 3 close to the second end B exceeds the first dashed line on the right.

[0079] As shown, Figure 6 the circular arc positions (dashed lines) on the second tab 100 and the first tab 200 correspond.

[0080] In this embodiment, the length of the recess 3 is not limited and is determined according to the situation. As an implementable manner, the length L of the recess 3 in the second direction Y is L=2a+2*n*b, a is the width of the wound cell, b is the thickness of the wound cell, and n is 1.2-2.

[0081] On the basis of the above-mentioned embodiments, in an embodiment of the present application, as shown, Figure 7 the recess 3 includes a groove, the active material layer 2 is distributed with the groove, and the current collector 1 is not distributed with the groove. That is, only the active material layer 2 is distributed with the recess.

[0082] In this embodiment, the groove can be obtained by cleaning the active material layer 2.

[0083] It should be noted that the number of active material layers 2 distributed with the groove in this embodiment is not limited and is determined according to the situation.

[0084] When the first tab 200 includes one layer of active material layer 2, the groove is located on the active material layer 2. When the first tab 200 includes two layers of active material layer 2, the groove can be located on any one of the two layers of active material layer 2, or simultaneously located on both layers of active material layer 2, which are all within the protection scope of the present application.

[0085] As an implementable manner, when the active material layer 2 on the first surface and the second surface of the current collector 1 is distributed with the groove, the projection of the groove on the first surface of the active material layer 2 on the current collector 1 can completely overlap with the projection of the groove on the second surface of the active material layer 2 on the current collector 1.

[0086] As one possible implementation, grooves are distributed on both the first and second surfaces of the current collector 1. The projection of the grooves on the active material layer 2 on the first surface of the current collector 1 onto the current collector 1 is staggered with the projection of the grooves on the active material layer 2 on the second surface of the current collector 1 onto the current collector 1, so as to avoid excessive local stress deformation causing wrinkling of the first electrode 200; to avoid the first electrode 200 having too low strength and breaking during the cycle; and at the same time, to reduce the difficulty of manufacturing.

[0087] It should be noted that the depth of the groove is not limited in this embodiment and can be set by the user.

[0088] As one possible implementation, in the first direction Z, the depth d of the groove is in the range of (20%D±7)≤d≤(80%D±7), where D is the thickness of the active material layer 2 in μm, and the depth d of the groove is less than the thickness of the active material layer.

[0089] In this embodiment, if the groove is too shallow, the first electrode 200 is prone to powder shedding; if the groove is too deep, the groove deformation is small and it cannot effectively suppress the extension of the first electrode 200.

[0090] like Figure 8 As shown, based on any of the above embodiments, in one embodiment of this application, when the groove is only located on the active material layer 2, in the second direction Y, the distance L1 between the end of the groove near the first end A and the edge of the active material layer 2 near the first end A is 0≤L1≤6mm.

[0091] For example, the distance L1 between the end of the groove near the first end A and the edge of the active material layer 2 near the first end A can be 0, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, etc. Among them, when the distance L1 between the end of the groove near the first end A and the edge of the active material layer 2 near the first end A is 0, that is, the end of the groove near the first end A is flush with the edge of the active material layer 2 near the first end A.

[0092] It should be noted that when the distance L1 between the end of the groove near the first end A and the edge of the active material layer 2 near the first end A is greater than 0, it means that the end of the groove near the first end A does not exceed the edge of the active material layer 2 near the first end A, that is, the empty current collector area 11 of the first electrode 200 has no groove.

[0093] If the distance between the end of the groove near the first end A and the edge of the active material layer 2 near the first end A is too large, the groove may not be able to cover the outermost arc of the wound cell, thus failing to solve the problem of arc breakage.

[0094] On the basis of the above embodiments, in one embodiment of the present application, as shown in Figure 9 The recess 3 comprises slits, and at least one of the active material layer 2 and the current collector 1 is provided with the slits in the first direction Z.

[0095] The slits 3 in the present embodiment can be made by die cutting.

[0096] It should be noted that the position of the slits in the present embodiment is not limited and can be determined as appropriate.

[0097] As one implementation, only one of the active material layer 2 and the current collector 1 is provided with the slits, as shown in Figures 2 to 4

[0098] As another implementation, as shown in Figure 10 The slit is also provided on the empty current collector area 11 of the current collector 1, and the empty current collector area is located at the first end A of the first tab 200, which can be used as a machining allowance when the slit is made to simplify the machining difficulty.

[0099] In one embodiment of the present application, in the second direction Y, the distance L2 between the end of the slit close to the first end A and the edge of the active material layer 2 close to the first end A ranges from 0 mm to 10 mm.

[0100] For example, the distance L2 between the end of the slit close to the first end A and the edge of the active material layer 2 close to the first end A can be 0 mm, 2 mm, 4 mm, 6 mm, 8 mm, 10 mm, etc.

[0101] In the second direction Y, when the distance L2 between the end of the slit close to the first end A and the edge of the active material layer 2 close to the first end A is 0, it means that the end of the slit close to the first end A is flush with the edge of the active material layer 2 close to the first end A. It can be understood that when the slit is provided on the empty current collector area 11, the distance L2 between the end of the slit close to the first end A and the edge of the active material layer 2 close to the first end A is the length of the slit on the empty current collector area 11; when the slit is not provided on the empty current collector area and only the slit is provided on the active material layer 2 and the current collector 1, the distance L2 between the end of the slit close to the first end A and the edge of the active material layer 2 close to the first end A is the distance of the slit from the edge of the active material layer 2 close to the first end A.

[0102] When the slit is provided on the empty current collector area 11, as shown in Figure 11 ​As shown, the length of the slit on the current collector region 11 in the second direction Y equal to the length of the current collector region 11, i.e. the current collector region 11 is cut through by the slit in the second direction Y, will result in the current collector region 11 being divided into at least two separate regions, which is not conducive to winding termination. Therefore, the length of the slit on the current collector region 11 in the second direction Y is preferably less than the length of the current collector region 11.

[0103] The application also provides a use electric device, which comprises the winding type battery cell as described in any of the above embodiments.

[0104] The first tab 200 in the application will be introduced in two different cases.

[0105] Example 1

[0106] The first tab 200 is a positive tab, the first surface of the current collector is distributed with an active material layer, the slit is located on the active material layer and the current collector, and the related parameters of the slit are as follows:

[0107] Slit width: 300 μm;

[0108] Slit number: 2;

[0109] The distance between the first slit and the upper edge of the active material layer: 12 mm;

[0110] The distance between the second slit and the lower edge of the active material layer: 12 mm;

[0111] The length of the slit in the second direction: 131.6 mm;

[0112] The distance between the slit and the edge of the active material layer in the second direction: 3 mm.

[0113] The manufacturing process of the first tab 200 in Example 1 generally includes: the positive current collector is selected as an aluminum foil with a thickness of 8 microns, the positive active material is selected as lithium cobaltate, and the lithium cobaltate, a binder (polyvinylidene difluoride, PVDF), a conductive agent (carbon black), and a solvent (N-Methylpyrrolidone, NMP) are mixed and stirred according to a certain proportion to prepare a slurry; the slurry is coated on the aluminum foil, and then baked, rolled, and cut to manufacture a positive tab; and then the obtained first tab is punched according to the slit parameters described above to form the slit.

[0114] Example 2

[0115] The first tab 200 is a positive tab, the first surface and the second surface of the current collector are distributed with an active material layer, and the slit is located on the two layers of active material layers, and the related parameters of the slit are as follows:

[0116] Slit width: 300 μm;

[0117] The number of slits: 2 on each active material layer;

[0118] The depth of the slit: 26 μm;

[0119] The distance between the first slit and the upper edge of the active material layer: 12 mm;

[0120] The distance between the second slit and the lower edge of the active material layer: 12 mm;

[0121] The length of the slit: 131.6 mm;

[0122] The distance between the slit and the edge of the active material layer in the second direction: 3 mm.

[0123] The manufacturing process of the first electrode sheet 200 in Example 2 generally includes: selecting an aluminum foil with a thickness of 8 microns as the positive electrode current collector, and selecting lithium cobaltate as the positive electrode active material, mixing and stirring the lithium cobaltate, a binder (polyvinylidene difluoride, PVDF), a conductive agent (carbon black), and a solvent (N-Methylpyrrolidone, NMP) in a certain proportion to prepare a slurry; coating the slurry onto the aluminum foil, then baking, rolling, and slitting to manufacture a positive electrode sheet; and then cleaning the obtained first electrode sheet according to the slit parameters described above to form a slit.

[0124] The manufacturing process of the wound cell is described below.

[0125] Scheme One: The wound cell has a width of 61.7 mm and a thickness of 4.09 mm. The positive electrode sheet uses the positive electrode sheet in Example 1 described above, and the negative electrode sheet has a negative electrode active material layer with a length of 1382 mm on the first surface of the negative electrode current collector and a length of 1269 mm on the second surface of the negative electrode current collector. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound to manufacture a wound cell.

[0126] Scheme Two: The wound cell has a width of 61.7 mm and a thickness of 4.09 mm. The positive electrode sheet uses the positive electrode sheet in Example 2 described above, and the negative electrode sheet has a negative electrode active material layer with a length of 1382 mm on the first surface of the negative electrode current collector and a length of 1269 mm on the second surface of the negative electrode current collector. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound to manufacture a wound cell.

[0127] Each of the embodiments in the specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other.

[0128] The above describes the pole piece and the battery cell provided by the application in detail. The principle and implementation of the application are described by applying specific examples, and the above description of the examples is only used to help understand the scheme of the application and its core idea. It should be pointed out that, for those skilled in the art, some improvements and modifications can be made to the application without departing from the principle of the application, and these improvements and modifications also fall within the protection scope of the application.

Claims

1. A wound cell, characterized by, The first electrode sheet, the separator, and the second electrode sheet are stacked and wound. The current collector; An active material layer on the first surface and / or the second surface of the current collector; the first surface and the second surface are two opposite surfaces in the first direction; At least one of the active material layers is provided with a recess, the recess is distributed from a first end of the first electrode sheet to a second end away from the first end in the second direction, the recess corresponds to the outermost circle of the wound battery cell; the second direction is perpendicular to the first direction, the first end is the winding end, and the second end is the winding start end.

2. The wound cell of claim 1, wherein, The recess includes a groove, and the active material layer is provided with the groove.

3. The wound cell of claim 2, wherein, In the first direction, the depth d of the groove ranges from (20%D±7) to (80%D±7), D is the thickness of the active material layer, and the depth d of the groove is less than the thickness of the active material layer.

4. The wound cell of claim 2, wherein, In the second direction, the distance L1 between one end of the groove close to the first end and the edge of the active material layer close to the first end ranges from 0 to 6 mm.

5. The wound cell of claim 2, wherein, The active material layers on the first surface and the second surface of the current collector are both provided with the groove, and the groove distributed on the active material layer on the first surface of the current collector is staggered with the projection of the groove distributed on the active material layer on the second surface of the current collector on the current collector.

6. The wound cell of claim 1, wherein, The recess includes a slit, and at least one of the active material layers and the current collector is provided with the slit in the first direction.

7. The wound cell of claim 6, wherein The empty current collector area of the current collector is also provided with the slit; the empty current collector area is located at the first end of the first electrode sheet.

8. The wound cell of claim 7, wherein, In the second direction, the distance L2 between one end of the slit close to the first end and the edge of the active material layer close to the first end ranges from 0 to 10 mm.

9. The wound cell of claim 1, wherein, The number N of the recesses ranges from 1 to 10; and / or, The width W2 of the recess in the third direction ranges from 100 μm to 400 μm, and the third direction is perpendicular to both the first direction and the second direction.

10. The wound cell of claim 9, wherein, When the number of the recesses is at least two, all the recesses are distributed along the third direction, which is perpendicular to both the first direction and the second direction; In the third direction, the distance W1 between the recesses on both sides and the edge of the active material layer closest to them ranges from 9 mm to 15 mm.

11. The wound cell of claim 1, wherein The first electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet.

12. The wound cell according to any one of claims 1 to 11, wherein One end of the recess close to the second end at least extends to the first outermost circular arc of the wound battery cell.

13. The wound cell of claim 12, wherein, The length L of the recess in the second direction is L=2a+2*n*b, a is the width of the wound battery cell, b is the thickness of the wound battery cell, and n is 1.2-2.

14. The wound cell of claim 12, wherein, One end of the recess close to the second end extends to the second outermost circular arc of the wound battery cell.

15. An electrical device, characterized by The wound battery cell comprises the wound battery cell according to any one of claims 1-14.

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