Winding battery cell and electric equipment

Abstract

The utility model relates to the field of lithium batteries, in particular to a winding battery cell and electric equipment. The winding battery cell comprises a positive pole piece and a negative pole piece, the negative pole piece comprises a negative pole current collector, a negative pole long surface active layer and a negative pole short surface active layer; the negative plate comprises a junction; in the first direction, the head starting end of the negative electrode long surface active layer is closer to the starting end of the negative electrode current collector than the head starting end of the negative electrode short surface active layer; the positive pole piece comprises a positive current collector and a first surface active layer; the first surface active layer is provided with a first groove; the first surface active layer is positioned on one side, far away from the center of the winding battery cell, of the junction, and an opening of the first groove faces the center of the winding battery cell; and the first groove corresponds to the joint in position. In addition, the first groove can accommodate the junction where the thickness of the negative pole piece changes suddenly in the winding process of the pole piece, so that the pole piece is prevented from being wrinkled or broken in the winding process of the winding machine.

Description

A wound battery cell and electrical equipment Technical Field

[0001] This utility model relates to the field of lithium batteries, and in particular to a wound battery cell and an electrical device. Background Technology

[0002] With the rapid development of the battery industry, the demand for high-energy and fast-charging batteries in electronic products is an inevitable trend. High energy density inevitably leads to high areal density and high compaction density on the electrodes. Under these circumstances, the high current density of fast charging requires the electrodes in the battery to have better kinetic performance.

[0003] In the existing cell structure, there is a single-sided area on the negative electrode sheet (that is, the area where the current collector has an active layer on only one side). Due to the thickening of the paste head, there will be a step at the junction of the single-sided area and the double-sided area (that is, the starting position of the double-sided area). During the rolling process, local overvoltage will occur at the step. Local overvoltage will make the battery more prone to lithium plating during subsequent cycles, affecting the cell cycle performance and even causing safety hazards of combustion.

[0004] In existing technologies, there are solutions to reduce the content of positive electrode active material at the junction of the single-sided and double-sided regions of the negative electrode sheet, thereby adjusting the NP ratio and solving the lithium plating problem. However, if the position of the positive electrode active material content adjustment is closer to the center of the winding core relative to the junction of the single-sided and double-sided regions, the adjusted position will be closer to the inside of the winding core or located at the winding head of the positive electrode sheet. This will cause the electrode sheet to wrinkle or break during the winding process due to uneven thickness of the positive electrode active layer, exacerbating the lithium plating phenomenon at the center of the winding core.

[0005] Therefore, how to avoid lithium plating at the junction of single and double sides of the wound cell, which would reduce the cycle performance of the wound cell, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a wound battery cell and an electrical device to solve the problem in the prior art where lithium plating easily occurs at the junction of single and double sides of the wound battery cell, which reduces the cycle performance of the wound battery cell.

[0007] To solve the above-mentioned technical problems, this utility model provides a wound battery cell, including a positive electrode and a negative electrode;

[0008] The positive electrode and the negative electrode extend along a first direction;

[0009] The negative electrode sheet includes a negative electrode current collector and an active material layer. The negative electrode current collector includes a first surface and a second surface disposed opposite to each other. The active material layer includes a negative electrode long surface active layer disposed on the first surface and a negative electrode short surface active layer disposed on the second surface. The negative electrode sheet includes a junction, and the two sides of the current collector at the junction are respectively the middle continuous section of the negative electrode long surface active layer and the head starting end of the negative electrode short surface active layer.

[0010] In the first direction, the head start end of the negative electrode long surface active layer is closer to the start end of the negative electrode current collector than the head start end of the negative electrode short surface active layer.

[0011] The positive electrode includes a positive current collector and a first active layer; the first active layer is provided with a first groove.

[0012] The first active layer is located on the side of the junction away from the center of the wound cell, and the opening of the first groove faces the center of the wound cell;

[0013] The first groove corresponds to the position of the junction.

[0014] Optionally, in the wound cell, the first groove penetrates the first surface active layer in the second direction;

[0015] The second direction is a direction perpendicular to the first direction within the plane where the positive electrode sheet is located.

[0016] Optionally, in the wound cell, the bottom surface of the first groove exposes the positive current collector.

[0017] Optionally, in the wound cell, in the thickness direction of the positive electrode sheet, the first groove has a depth D1, and the first active layer without the first groove has a thickness T, where D1 and T satisfy the following formula:

[0018] D1 = n*T ± 7um;

[0019] 0.4≤n≤0.6.

[0020] Optionally, in the wound cell, the first groove has a width L in the first direction, where L satisfies 6mm ≤ L ≤ 10mm.

[0021] Optionally, in the wound cell, the centerline of the width of the first groove in the first direction has a distance C between the projection of the head of the negative electrode short-face active layer onto the positive electrode sheet, where C satisfies 0.5mm≤C≤7mm.

[0022] Optionally, in the wound cell, the positive electrode sheet includes a positive current collector and a positive active material layer, and the positive active material layer is provided with a plurality of second grooves.

[0023] Optionally, in the wound cell, the second groove has a depth D2 in the thickness direction of the positive electrode sheet, where D2 satisfies 70um≤D2≤150um.

[0024] Optionally, in the wound battery cell, the area where the second groove is set is a slotted area;

[0025] In the first direction, a first clearance area exists between the grooved area and the beginning of the head of the positive electrode active material layer; the first clearance area has a width K1 along the first direction, where K1 satisfies 40mm≤K1≤70mm;

[0026] And / or, in the first direction, a second clearance area exists between the slotted area and the first groove; the second clearance area has a width K2 along the first direction, K2 satisfying 5mm≤K2≤35mm;

[0027] And / or, in the first direction, a third clearance area exists between the slotted area and the tab groove area of ​​the positive electrode sheet; the third clearance area has a width K3 along the first direction, K3 satisfying 5mm≤K3≤35mm;

[0028] In the first direction, there is a fourth clearance area between the slotted area and the tail end of the positive active material layer near the starting end of the positive electrode sheet; the fourth clearance area has a width K4 along the first direction, and K4 satisfies 5mm≤K1≤35mm;

[0029] The second groove is not provided in the first, second, third, and fourth clearance zones.

[0030] Optionally, in the wound cell, in the second direction, there is a spacing W between the slotted area and the edge of the first surface active layer, where W satisfies 2mm≤W≤12mm;

[0031] The second direction is a direction perpendicular to the first direction within the plane where the positive electrode sheet is located.

[0032] An electrical device comprising any of the above-described wound battery cells.

[0033] The wound battery cell provided by this utility model includes a positive electrode and a negative electrode; the positive electrode and the negative electrode extend along a first direction; the negative electrode includes a negative current collector, a negative long-face active layer, and a negative short-face active layer; the negative electrode includes a junction, with the current collector at the junction having a continuous middle section of the negative long-face active layer and a head starting end of the negative short-face active layer on both sides; in the first direction, the head starting end of the negative long-face active layer is closer to the starting end of the negative current collector than the head starting end of the negative short-face active layer; the positive electrode includes a positive current collector and a first-face active layer; the first-face active layer is provided with a first groove; the first-face active layer is located on the side of the junction away from the center of the wound battery cell, and the opening of the first groove faces the center of the wound battery cell; the first groove corresponds to the junction.

[0034] This invention reduces the lithium content in the first active layer corresponding to the junction (i.e., the junction of the single-sided and double-sided negative electrode regions mentioned earlier) by creating a groove in the region on the positive electrode sheet corresponding to the beginning of the short-sided active layer of the negative electrode. This makes the negative electrode sheet at this location less prone to lithium saturation. Simultaneously, the groove can accommodate the junction of abrupt changes in the thickness of the negative electrode sheet during winding, preventing wrinkling or breakage of the electrode sheet during the winding process. These two reasons together achieve the lithium-free effect of this invention and significantly improve the cycle performance and operational safety of the wound battery cell. This invention also provides an electrical device with the above-mentioned beneficial effects. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 is a schematic diagram of the unfolded structure of a specific embodiment of the wound battery cell provided by this utility model;

[0037] Figure 2 is a cross-sectional structural schematic diagram of a specific embodiment of the wound battery cell provided by this utility model;

[0038] Figure 3 is a cross-sectional structural schematic diagram of another specific embodiment of the wound battery cell provided by this utility model;

[0039] Figure 4 is a partial structural schematic diagram of a specific embodiment of the wound battery cell provided by this utility model;

[0040] Figure 5 is a partial structural schematic diagram of another specific embodiment of the wound battery cell provided by this utility model.

[0041] The figure includes 100 - negative electrode sheet, 200 - positive electrode sheet, 110 - negative electrode current collector, 120 - negative electrode long surface active layer, 130 - negative electrode short surface active layer, 101 - junction, 140 - negative electrode tab, 210 - positive electrode current collector, 220 - positive electrode active material layer, 220A - first surface active layer, 221 - first groove, 222 - second groove, and 230 - positive electrode tab. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The core of this utility model is to provide a wound battery cell. A schematic diagram of one specific embodiment is shown in Figure 1, which is referred to as Specific Embodiment 1, including a positive electrode 200 and a negative electrode 100.

[0044] The positive electrode 200 and the negative electrode 100 extend along the first direction;

[0045] The negative electrode sheet 100 includes a negative electrode current collector and an active material layer. The negative electrode current collector includes a first surface and a second surface disposed opposite to each other. The active material layer includes a negative electrode long surface active layer 120 disposed on the first surface and a negative electrode short surface active layer 130 disposed on the second surface.

[0046] The negative electrode 100 includes a junction 101, on both sides of the current collector of the junction 101 being the middle continuous section of the long surface active layer 120 of the negative electrode and the head starting end of the short surface active layer 130 of the negative electrode, respectively.

[0047] In the first direction, the head of the long-faceted active layer 120 is closer to the head of the current collector 110 than the head of the short-faceted active layer 130.

[0048] The positive electrode 200 includes a positive current collector 210 and a first active layer 220A; the first active layer 220A is provided with a first groove 221;

[0049] The first active layer 220A is located on the side of the junction 101 away from the center of the wound cell, and the opening of the first groove 221 faces the center of the wound cell.

[0050] The first groove 221 corresponds to the junction 101.

[0051] The first direction is the extension direction of the positive electrode 200 and the negative electrode 100. Therefore, the first direction will change depending on the position on the wound cell.

[0052] Please refer to Figure 1. Figure 1 is a structural schematic diagram of the two surfaces of the negative electrode 100 and the surface where the first active layer 220A of the positive electrode 200 is located. It can be seen that the starting positions of the heads of the active layers (i.e., the long-faced active layer 120 and the short-faced active layer 130) on the two surfaces of the negative electrode 100 are not the same. This results in the presence of both single-sided and double-sided active layer areas on the negative electrode 100. At the junction of the single and double sides (i.e., the junction 101), the thickness of the negative electrode 100 will change abruptly. The starting position of the head of the short-faced active layer 130 is the position where the short-faced active layer 130 begins to be coated. The continuous middle section of the long-faced active layer 120 refers to the part of the long-faced active layer 120, not the starting position of the head.

[0053] In addition, the corresponding tabs of the two electrodes are also marked in Figure 1, namely the positive electrode tab 230 and the negative electrode tab 140. The junction 101 is outlined with a dashed line and the first direction is indicated by an arrow.

[0054] The phrase “the first groove 221 corresponds to the junction 101” means that the projection of the head of the negative short-face active layer 130 onto the positive electrode sheet 200 falls into the first groove 221.

[0055] The first groove 221 can be a groove obtained by laser surface scanning or a groove obtained by roller pressing technology. This utility model will not elaborate on this. The bottom surface of the laser-scanned groove is flat and the depth is highly controllable, making it suitable as the grooving type of this utility model.

[0056] In one specific embodiment, the first groove 221 penetrates the first surface active layer 220A in the second direction;

[0057] The second direction is the direction perpendicular to the first direction within the plane where the positive electrode plate 200 is located.

[0058] The second direction can be considered as the width direction of the positive electrode 200. The first groove 221 penetrates the positive electrode 200 in the width direction, which reduces the difficulty of aligning the first groove 221 with the head start end of the negative short-surface active layer 130, reduces the process difficulty, and improves the process efficiency.

[0059] In another specific implementation, the bottom surface of the first groove 221 exposes the positive current collector 210.

[0060] In other words, the first groove 221 completely hollows out the first active layer 220A at the corresponding position. This not only provides the negative electrode 100 at the junction 101 with the greatest possible clearance during the winding process, but also further reduces the difficulty of the process.

[0061] Furthermore, in the thickness direction of the positive electrode 200, the first groove 221 has a depth D1, and the first surface active layer without the first groove has a thickness T, where D1 and T satisfy the following equations (1) and (2):

[0062] D1=n*T±7um; (1)

[0063] 0.4≤n≤0.6. (2)

[0064] Wherein, D1 is the depth of the first groove 221, T is the thickness of the first active layer without the first groove, and n is a preset coefficient. Please refer to Figure 4, where the above parameters are marked. When the thickness of the first active layer without the first groove and the depth of the first groove 221 satisfy the relationship specified by equations (1) and (2), the first groove 221 can accommodate the negative electrode sheet 100 with a sudden change in thickness during the winding process, and will not cause damage to the structure of the positive electrode sheet 200 due to the groove. In addition, the first groove 221 has a width L in the first direction, where L satisfies 6mm≤L≤10mm, such as any one of 6.0mm, 8.5mm, or 10.0mm; the centerline of the width of the first groove 221 in the first direction has a distance C between it and the projection of the head of the negative short active layer 130 onto the positive electrode sheet 200, where C satisfies 0.5mm≤C≤7mm, such as at least one of 0.50mm, 2.78mm, or 7.00mm.

[0065] The above parameter ranges and relationships are derived from extensive theoretical calculations and practical verifications. Of course, other parameter ranges can be selected according to actual needs, and this utility model does not limit them here.

[0066] In this specific embodiment, the junction 101 in the wound cell can be positioned as shown in Figures 2 and 3.

[0067] First, when the junction 101 is located in front of the arc segment, the first groove 221 is positioned at a certain distance from the arc to avoid the first groove 221 being placed on the arc, which would affect the flatness of the arc area. See Figure 2 for reference. Preferably, when the junction 101 is located in front of the arc segment, the distance A1 from the first groove 221 to the arc satisfies: 5mm ≥ A1 ≥ 0.1mm.

[0068] Secondly, there is the case where the junction 101 is located on an arc. In this case, during the winding process, due to the bending, the first groove 221 can provide a larger space to accommodate the junction 101 with its sudden thickness change. Furthermore, setting the first groove 221 on the arc can alleviate the problem of electrode expansion, which could lead to insufficient electrolyte causing lithium plating or excessive expansion causing electrode breakage. See Figure 3. Preferably, the distance A2 between the centerline of the first groove 221 and the centerline of the arc segment satisfies: 5mm ≥ A2 ≥ 0.

[0069] Of course, after the positive electrode 200 and the negative electrode 100 are made into a core, aluminum-plastic film can be used to encapsulate the core.

[0070] The wound battery cell provided by this utility model includes a positive electrode 200 and a negative electrode 100; the positive electrode 200 and the negative electrode 100 extend along a first direction; the negative electrode 100 includes a negative current collector 110, a negative long-faced active layer 120, and a negative short-faced active layer 130; the negative electrode 100 includes a junction 101, with the current collector on both sides of the junction 101 being a continuous middle section of the negative long-faced active layer 120 and the beginning of the negative short-faced active layer 130, respectively; in the first direction, the negative... The starting end of the long surface active layer 120 is closer to the starting end of the negative current collector 110 than the starting end of the short surface active layer 130. The positive electrode 200 includes a positive current collector 210 and a first surface active layer 220A. The first surface active layer 220A is provided with a first groove 221. The first surface active layer 220A is located on the side of the junction 101 away from the center of the wound cell, and the opening of the first groove 221 faces the center of the wound cell. The first groove 221 corresponds to the position of the junction 101. This invention reduces the lithium content in the first active layer 220A corresponding to the junction 101 (i.e., the junction of the single-sided and double-sided areas of the negative electrode) by creating a groove in the region on the positive electrode 200 corresponding to the head start end of the short-sided active layer 130 of the negative electrode. This makes the negative electrode 100 less prone to lithium saturation at this location. At the same time, the first groove 221 can also accommodate the junction 101 where the thickness of the negative electrode 100 changes abruptly during the electrode winding process, preventing the electrode from wrinkling or breaking during the winding process. The above two reasons together achieve the effect of preventing lithium deposition in this invention, and also greatly improve the cycle performance and working safety of the wound battery cell.

[0071] Based on the first specific implementation method, the positive electrode 200 is further improved to obtain the second specific implementation method. The corresponding partial structural schematic diagram is shown in Figure 4, which includes the positive electrode 200 and the negative electrode 100.

[0072] The positive electrode 200 and the negative electrode 100 extend along the first direction;

[0073] The negative electrode 100 includes a negative current collector 110, a negative long-face active layer 120, and a negative short-face active layer 130;

[0074] The negative electrode 100 includes a junction 101, on both sides of the current collector of the junction 101 being the middle continuous section of the long surface active layer 120 of the negative electrode and the head starting end of the short surface active layer 130 of the negative electrode, respectively.

[0075] In the first direction, the head of the long-faceted active layer 120 is closer to the head of the current collector 110 than the head of the short-faceted active layer 130.

[0076] The positive electrode 200 includes a positive current collector 210 and a first active layer 220A; the first active layer 220A is provided with a first groove 221;

[0077] The first active layer 220A is located on the side of the junction 101 away from the center of the wound cell, and the opening of the first groove 221 faces the center of the wound cell.

[0078] The first groove 221 corresponds to the junction 101;

[0079] The positive electrode 200 includes a positive current collector 210 and a positive active material layer 220, and a plurality of second grooves 222 are provided on the positive active material layer 220.

[0080] The difference between this specific embodiment and the above specific embodiment is that a second groove 222 is formed on the positive electrode plate 200 in this specific embodiment. The rest of the structure is the same as the above specific embodiment, and will not be described in detail here.

[0081] In this preferred embodiment, a plurality of second grooves 222 are provided on the positive electrode active material layer 220. The additional grooves on the positive electrode active material layer 220 can increase the electrolyte retention of the cell, thereby improving cell performance. The second grooves 222 can be created by laser scanning or by roll forming; the specific application is not limited here. The second grooves 222 improve the overall electrolyte retention of the cell and enhance its overall dynamic performance. Furthermore, if the second grooves 222 are created by roll forming, the current collector of the electrode sheet will bend and form waves, preventing the positive electrode sheet 200 from breaking during repeated use.

[0082] Specifically, the second groove 222 has a depth D2 in the thickness direction of the positive electrode 200, and D2 satisfies 70um≤D2≤150um, such as any one of 70.0um, 102.4um or 150.0um.

[0083] In addition, the area where the second groove 222 is set is a slotted area;

[0084] In the first direction, a first clearance area exists between the grooved area and the beginning of the positive electrode active material layer; the first clearance area has a width K1 along the first direction, K1 satisfying 40mm≤K1≤70mm, such as any one of 40.0mm, 52.1mm or 70.0mm;

[0085] And / or, in the first direction, a second clearance area exists between the slotted area and the first groove; the second clearance area has a width K2 along the first direction, K2 satisfying 5mm≤K2≤35mm, such as any one of 5.0mm, 12.1mm or 35.0mm;

[0086] And / or, in the first direction, a third clearance area exists between the slotted area and the tab groove area of ​​the positive electrode 200; the third clearance area has a width K3 along the first direction, K3 satisfying 5mm≤K3≤35mm, such as any one of 5.0mm, 32.1mm or 35.0mm;

[0087] In the first direction, there is a fourth clearance area between the slotted area and the tail end of the positive active material layer near the starting end of the positive electrode sheet 200; the fourth clearance area has a width K4 along the first direction, K4 satisfying 5mm≤K4≤35mm, such as any one of 5.0mm, 32.1mm or 35.0mm;

[0088] As explained earlier, the slotted area is the region where the second groove 222 is provided. Therefore, the various clearance areas described earlier are the regions outside the slotted area where the second groove 222 is not provided. In other words, the second groove 222 is not provided in the first, second, third, and fourth clearance areas. Refer to Figure 5, which marks the widths of the aforementioned first, second, third, and fourth clearance areas. The above parameter ranges are all optimal ranges after extensive theoretical calculations and practical verification. After setting the first groove 221, the position of the first groove 221 will be locally bent due to less paste applied on one side. If a second groove 222 is opened around the first groove 221, it will likely cause the positive electrode sheet 200 to wrinkle. The deeper either groove is, the higher the probability. In this preferred embodiment, after setting the second clearance area between the slotted area (which can also be regarded as the second groove 22) and the first groove 221, a certain buffer space can be left between the first groove 221 and the second groove 222, avoiding the two grooves from being too close to cause local bending and wrinkling, thereby greatly improving the yield of the finished battery cell. The first clearance zone is located between the slotted area and the beginning of the positive electrode active material layer. This prevents the electrode head from bending and wrinkling due to the second groove 222, which could cause difficulties in winding the core during production. The third clearance zone is designed to prevent damage to the current collector in the tab groove area of ​​the positive electrode 200 due to further slotting (setting the second groove), which could affect the welding of the current collector and the tab, or cause the current collector to break after welding the tab. The fourth clearance zone is designed to address the thickness change on both sides of the current collector of the positive electrode 200 (where one side of the positive electrode active material layer terminates, creating a junction between a single-sided and double-sided area). Therefore, K4 is required to prevent the active layer from falling off due to the second groove 222 at the junction, which could lead to a short circuit between the positive and negative electrodes.

[0089] Furthermore, there is a spacing W between the grooved area and the edge of the first active layer 220A, where W satisfies 2mm≤W≤12mm, and any one of 2.0mm, 5.3mm, or 12.0mm; the second direction is a direction perpendicular to the first direction within the plane of the positive electrode 200.

[0090] Leaving a gap W between the grooved area and the edge of the first active layer 220A, i.e., leaving a gap between the second groove 222 and the edge, can significantly reduce the occurrence of local wrinkling on the electrode and improve product yield.

[0091] Preferably, at least one of the first groove 221 and the second groove 222 is laser-grooved. Using a laser to groove the current collector in the electrode will not cause additional pressure. It can keep the current collector straight while obtaining the corresponding groove, thus improving the quality of the battery cell.

[0092] This utility model also provides an electrical device, which includes any of the above-mentioned wound battery cells. The wound battery cell provided by this utility model includes a positive electrode 200 and a negative electrode 100; the positive electrode 200 and the negative electrode 100 extend along a first direction; the negative electrode 100 includes a negative current collector 110, a negative long-faced active layer 120, and a negative short-faced active layer 130; the negative electrode 100 includes a junction 101, with the current collector at the junction 101 having a continuous middle section of the negative long-faced active layer 120 and a starting head of the negative short-faced active layer 130 on either side; in the first direction, the negative... The starting end of the long surface active layer 120 is closer to the starting end of the negative current collector 110 than the starting end of the short surface active layer 130. The positive electrode 200 includes a positive current collector 210 and a first surface active layer 220A. The first surface active layer 220A is provided with a first groove 221. The first surface active layer 220A is located on the side of the junction 101 away from the center of the wound cell, and the opening of the first groove 221 faces the center of the wound cell. The first groove 221 corresponds to the position of the junction 101. This invention reduces the lithium content in the first active layer 220A corresponding to the junction 101 by creating a groove in the region on the positive electrode 200 corresponding to the head start end of the negative electrode short-side active layer 130. This makes the negative electrode 100 less prone to lithium saturation at this location. At the same time, the first groove 221 can also accommodate the junction 101 where the thickness of the negative electrode 100 changes abruptly during the electrode winding process, preventing the electrode from wrinkling or breaking during the winding process. The above two reasons together achieve the effect of preventing lithium deposition in this invention, and also greatly improve the cycle performance and working safety of the wound battery cell.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0094] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0095] The wound battery cell and electrical equipment provided by this utility model have been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of this utility model.

Claims

1. A wound battery cell, characterized in that, The device includes a positive electrode and a negative electrode; the positive electrode and the negative electrode extend along a first direction; the negative electrode includes a negative current collector and an active material layer, the negative current collector including a first surface and a second surface disposed opposite to each other; the active material layer includes a long-faced negative active layer disposed on the first surface and a short-faced negative active layer disposed on the second surface; the negative electrode includes a junction, the current collector at the junction being a continuous middle section of the long-faced negative active layer and the beginning end of the short-faced negative active layer on both sides of the electrode thickness direction; in the first direction, the beginning end of the long-faced negative active layer is closer to the beginning end of the negative current collector than the beginning end of the short-faced negative active layer; the positive electrode includes a positive current collector and a first-faced active layer; the first-faced active layer is provided with a first groove; the first-faced active layer is located on the side of the junction away from the center of the wound cell, and the opening of the first groove faces the center of the wound cell; the first groove corresponds to the position of the junction.

2. The wound battery cell as described in claim 1, characterized in that, The first groove penetrates the first surface active layer in a second direction; the second direction is a direction perpendicular to the first direction within the plane where the positive electrode sheet is located.

3. The wound battery cell as described in claim 1, characterized in that, The bottom surface of the first groove exposes the positive current collector.

4. The wound battery cell as described in claim 1, characterized in that, In the thickness direction of the positive electrode sheet, the first groove has a depth D1, and the first active layer without the first groove has a thickness T. D1 and T satisfy the following formula: D1=n*T±7um; 0.4≤n≤0.6。 5. The wound battery cell as described in claim 1, characterized in that, The first groove has a width L in the first direction, where L satisfies 6mm ≤ L ≤ 10mm.

6. The wound battery cell as described in claim 1, characterized in that, The centerline of the width of the first groove in the first direction has a distance C between it and the projection of the head of the negative electrode short-face active layer onto the positive electrode sheet, wherein C satisfies 0.5mm≤C≤7mm.

7. The wound battery cell as described in claim 1, characterized in that, The positive electrode includes a positive current collector and a positive active material layer, and the positive active material layer is provided with a plurality of second grooves.

8. The wound battery cell as described in claim 7, characterized in that, The second groove has a depth D2 in the thickness direction of the positive electrode sheet, where D2 satisfies 70um≤D2≤150um.

9. The wound battery cell as described in claim 7, characterized in that, The area where the second groove is set is a slotted area; in the first direction, there is a first clearance area between the slotted area and the starting end of the positive electrode active material layer; the first clearance area has a width K1 along the first direction, K1 satisfying 40mm≤K1≤70mm; and / or, in the first direction, there is a second clearance area between the slotted area and the first groove; the second clearance area has a width K2 along the first direction, K2 satisfying 5mm≤K2≤35mm; and / or, in the first direction, the slotted area and the... A third clearance area exists between the tab groove region of the positive electrode sheet; the third clearance area has a width K3 along the first direction, K3 satisfying 5mm≤K3≤35mm; in the first direction, a fourth clearance area exists between the slotted area and the tail end of the positive active material layer near the starting end of the positive electrode sheet; the fourth clearance area has a width K4 along the first direction, K4 satisfying 5mm≤K1≤35mm; the second groove is not provided in the first clearance area, the second clearance area, the third clearance area and the fourth clearance area.

10. The wound battery cell as described in claim 9, characterized in that, In the second direction, there is a distance W between the grooved area and the edge of the first surface active layer, where W satisfies 2mm≤W≤12mm; the second direction is the direction perpendicular to the first direction within the plane where the positive electrode sheet is located.

11. An electrical appliance, characterized in that, The electrical equipment includes the wound battery cell as described in any one of claims 1 to 10.

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