Battery cell

Abstract

The utility model discloses a battery cell, and relates to the technical field of batteries. The battery cell comprises a first pole piece group and a second pole piece group; the first pole piece group and the second pole piece group are stacked, the size of the second pole piece group along the first direction is smaller than that of the first pole piece group along the first direction, and a step is formed on at least one end of the stacked whole of the first pole piece group and the second pole piece group along the first direction; a concave-convex area and a clearance area are arranged on one side of the thickness direction of the first pole piece in the first pole piece group and the second pole piece group, and a plurality of concave parts are arranged in the concave-convex area; and the projection of the step to the first pole piece group is located in the clearance area. The concave-convex area with the concave part is arranged on the first pole piece, so that the distance between the adjacent pole pieces on the two sides of the step in the first direction is increased and tends to be consistent with the distance between the adjacent pole pieces at the step, and the consistency of the overall cohesive force of the step battery is improved; and the interface form of the step battery can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and more particularly to a battery cell. BACKGROUND

[0002] The new type of stepped lamination battery is gradually applied in high-end electronic products due to the advantages of high energy density, long cycle life, high space utilization rate and the like.

[0003] The stepped lamination battery is made by stacking a small stack on the basis of a large stack. The gap between the large and small stacks is difficult to compact and fix during formation, so the gap at the step is large, the distance between the positive and negative plates is relatively far, and the transmission path of lithium ions is lengthened. The gap on both sides of the step is small, the distance between the positive and negative plates is relatively close, and the transmission path of lithium ions is relatively short. Due to the preferential movement of lithium ions to both sides of the gap, there are too many lithium ions at the position around the gap corresponding to the negative plate, which further causes lithium dendrites to be precipitated, thereby causing black spots to appear at the position of the gap corresponding to the negative plate of the large stack.

[0004] In summary, how to prevent excessive deposition of lithium ions in any area of the negative plate is a problem that needs to be solved by those skilled in the art. CONTENT OF THE UTILITY MODEL

[0005] Therefore, the purpose of the present application is to provide a battery cell. By providing a concave-convex area with a recess on the first plate, the distance between the adjacent plates on both sides of the step in the first direction is increased, the distance between the adjacent plates at the step tends to be uniform, the uniformity of the overall adhesion of the stepped battery is improved, the lithium ion transmission path tends to be uniform, the uniform distribution of lithium ions on the negative plate during charging and discharging is met, the excessive deposition of lithium ions in any area of the negative plate is prevented, and the interface morphology of the stepped battery is improved.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] A battery cell comprises:

[0008] A first plate group, the first plate group comprising a first plate and a separator;

[0009] A second plate group, the second plate group comprising a second plate and a separator;

[0010] The first plate group and the second plate group are stacked, the size of the second plate group along the width direction of the second plate group is smaller than the size of the first plate group along the width direction of the first plate group, and the overall stacked first plate group and second plate group form a step at at least one end in the first direction;

[0011] A side of the first pole piece in the thickness direction of the first pole piece group and the second pole piece group is provided with a concave-convex region and a void region; the concave-convex region is provided with a plurality of concave portions, and the projection of the first pole piece group in the thickness direction of the second pole piece group is located in the void region.

[0012] Optionally, in the first direction, the boundary of the void region is beyond the projection of the first pole piece group in the thickness direction of the second pole piece group; and / or;

[0013] The void region is located on the pole piece of the second pole piece group close to the first pole piece group; and / or;

[0014] A side of the first pole piece away from the concave portion is provided with a protrusion at a position corresponding to the concave portion, and / or

[0015] The second pole piece of the second pole piece group comprises a concave-convex region and a non-concave-convex region, and the non-concave-convex region is located on a side of the concave-convex region along the width direction of the second pole piece;

[0016] The projection of the non-concave-convex region in the thickness direction of the second pole piece group at least partially overlaps with the void region of the first pole piece.

[0017] Optionally, in the first direction, the distance between the edge of the second pole piece group and the end of the void region away from the second pole piece group is a first distance L2, and the ratio of the first distance L2 to the length L1 of the void region in the first direction is in the range of: .

[0018] Optionally, the length L1 of the void region in the first direction is in the range of 2mm-10mm; and / or;

[0019] The size of the first distance L2 is in the range of 0.4mm-8mm.

[0020] Optionally, the area of the first pole piece is S, the length of the first pole piece in the first direction is L, and the area of the void region is .

[0021] The ratio of the area of the void region to the area of the first pole piece is in the range of: .

[0022] And / or, the ratio of the length of the void region in the first direction to the length of the first pole piece in the first direction is in the range of: .

[0023] And / or;

[0024] The area S of the first pole piece is in the range of 100mm2 -12000 mm 2 ; and / or;

[0025] the area of the avoidance region in the range of 10 mm 2 -1200 mm 2 .

[0026] Optionally, the edge of the concave-convex region has a first gap T1 with one end of the first tab where the tab is provided, and the edge of the concave-convex region has a second gap T2 with one end of the second tab away from the tab; the size of the first gap T1 and / or the second gap T2 along the second direction is smaller than the interval W1 of the two adjacent concave portions along the second direction.

[0027] Optionally, the first tab includes a tab ear and a ceramic region on the tab ear;

[0028] The ceramic region in the tab ear is provided with the concave portion.

[0029] Optionally, the thickness of the position of the first tab where the concave portion is not provided is h, the depth of the concave portion is h2, the thickness of the position of the first tab where the concave portion is provided is h1, and .

[0030] Optionally, the first tab group includes a first sub-tab on the top layer, and the first sub-tab includes a first current collector and a first active layer on a side surface of the first current collector close to the second tab group;

[0031] The concave portion is formed on a side surface of the first sub-tab away from the first active layer.

[0032] Optionally, the first tab of the first tab group close to the second tab group and the second tab of the second tab group close to the first tab group are bonded.

[0033] The application provides an electric core, which includes a first tab group and a second tab group; the first tab group and the second tab group are stacked, the size of the second tab group along the first direction is smaller than the size of the first tab group along the first direction, and the whole of the stacked first tab group and second tab group forms a step at at least one end in the first direction; one side of the first tab in the first tab group and the second tab group in the thickness direction is provided with a concave-convex region and an avoidance region, and the concave-convex region is provided with a plurality of concave portions; one side of the first tab away from the concave portion is provided with a convex portion at the position corresponding to the concave portion, and the projection of the step to the first tab group is located in the avoidance region.

[0034] The electric core provided by the application has the following beneficial effects:

[0035] 1、By setting the concave-convex area with recess on the first tab, the distance between the adjacent tabs on both sides of the step in the first direction is increased, the distance between the adjacent tabs at the step tends to be consistent, the consistency of the overall adhesion of the step cell is improved, the lithium ion transmission path tends to be consistent, the uniform distribution of lithium ions on the negative tab during the charging and discharging process is met, the deposition of lithium ions in any area of the negative tab is prevented, and the interface morphology of the step cell is improved.

[0036] 2、The recess on the first tab can form a liquid storage tank to accommodate electrolyte, thereby improving the wettability of the electrolyte to the tab, and thereby increasing the cycle life of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0038] Figure 1 Structure diagram of a specific embodiment of the positive tab in the first tab group in the battery provided by the present application;

[0039] Figure 2 Structure diagram of a specific embodiment of the negative tab in the first tab group in the battery provided by the present application;

[0040] Figure 3 Structure diagram of a specific embodiment of the combination of the first tab group and the second tab group in the battery provided by the present application;

[0041] Figure 4 Structure diagram of a specific embodiment of the first tab provided by the present application;

[0042] Figure 5 Structure diagram of a specific embodiment of the first tab provided by the present application;

[0043] Figure 6 Structure diagram of a specific embodiment of the first tab provided by the present application; Figure 5 Enlarged view of part of the structure;

[0044] Figure 7 Structure diagram of the distance between adjacent recesses in the first tab in the first direction and the second direction;

[0045] Figure 8 Structure diagram of a specific embodiment of the recess provided by the present application;

[0046] Figure 9 Structure diagram of a specific embodiment of the recess provided by the present application;

[0047] Figure 10 A schematic diagram of a peeling force of a battery including the battery cell provided in the present application.

[0048] Figures 1-10 In the present application,

[0049] 1 is a first pole piece group, 2 is a second pole piece group, 3 is a positive pole piece, 4 is a negative pole piece, 5 is a pole lug, 51 is a ceramic area, 6 is a void area, 7 is a concave-convex area, and 71 is a concave part. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0051] The core of the present application is to provide a battery cell. By providing a concave-convex area with a concave part on the first pole piece, the spacing between the adjacent pole pieces on both sides of the step in the first direction is increased, the spacing between the adjacent pole pieces at the step tends to be consistent, the overall adhesion consistency of the step battery is improved, the lithium ion transmission path tends to be consistent, the uniform distribution of lithium ions on the negative pole piece in the charging and discharging process is met, the excessive deposition of lithium ions in any area of the negative pole piece is prevented, and the interface morphology of the step battery is improved.

[0052] Embodiment 1

[0053] The present specific embodiment discloses a battery cell. The battery cell includes a first pole piece group 1 and a second pole piece group 2. The first pole piece group 1 includes a first pole piece and a separator. The second pole piece group 2 includes a second pole piece and a separator.

[0054] The first pole piece group 1 and the second pole piece group 2 are stacked and arranged. The size of the second pole piece group 2 along the width direction of the second pole piece group 1 is smaller than the size of the first pole piece group 1 along the width direction of the first pole piece group 1. The overall arrangement of the first pole piece group 1 and the second pole piece group 2 forms a step at at least one end in the first direction. One side of the first pole piece in the first pole piece group 1 and the second pole piece group 2 in the thickness direction is provided with a concave-convex area 7 and a void area 6. The concave-convex area 7 is provided with a plurality of concave parts 71. One side of the first pole piece away from the concave part 71 is provided with a protrusion at a position corresponding to the concave part 71. The projection of the step along the thickness direction of the second pole piece group 2 in the first pole piece group 1 is located in the void area 6.

[0055] The first pole piece group 1 and the second pole piece group 2 in the present specific embodiment each include a positive pole piece 3 and a negative pole piece 4 stacked and arranged. The first pole piece in the present specific embodiment can be the positive pole piece 3 or the negative pole piece 4, which is determined according to the actual situation.

[0056] In some example embodiments, the positive electrode sheet can include a positive electrode current collector and a positive electrode active material layer disposed on a surface of the positive electrode current collector. The positive electrode current collector can be exemplarily an aluminum foil, although other positive electrode current collectors commonly used in the art can be used. The thickness of the positive electrode current collector can be 1 μm to 200 μm. The positive electrode active material layer can be disposed on one surface or both opposite surfaces of the positive electrode current collector. Further, the positive electrode active material layer can be coated only on a partial area of the positive electrode current collector in the thickness direction of the positive electrode sheet. The thickness of the positive electrode active material layer can be 10 μm to 500 μm.

[0057] The positive electrode active material layer includes a positive electrode active material including LiCoO2, LiNiO2, LiMn2O4, LiCo1-yMyO2, LiNi1-yMyO2, LiMn2-yMyO4, LiNixCoyMnzM1-x-y-zO2, wherein M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, or Ti, and 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1. The positive electrode active material can exemplarily include at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese phosphate, lithium nickel cobalt aluminum phosphate, or lithium nickel manganese phosphate. The positive electrode active material can be subjected to a doping and / or coating process. The positive electrode active material layer further includes a binder and a conductive agent. The binder in the positive electrode active material layer can exemplarily include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, a polyamide, a polyacrylonitrile, a polyacrylate, a polyacrylic acid, a polyacrylate salt, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, a polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. The conductive agent in the positive electrode active material layer can include at least one of conductive carbon black, acetylene black, ketjen black, flake graphite, graphene, carbon nanotubes, or carbon fibers.

[0058] In some example embodiments, the negative electrode sheet can include a negative electrode current collector and a negative electrode active material layer disposed on a surface of the negative electrode current collector. The negative electrode current collector can be exemplarily at least one of a copper foil, an aluminum foil, a nickel foil, or a carbon-based current collector. The thickness of the negative electrode current collector can be 1 μm to 200 μm. The negative electrode active material layer can be disposed on one surface or both opposite surfaces of the negative electrode current collector. Further, the negative electrode active material layer can be coated only on a partial area of the negative electrode current collector in the thickness direction of the negative electrode sheet. The thickness of the negative electrode active material layer can be exemplarily 10 μm to 500 μm.

[0059] The negative active material layer includes a negative active material, which is exemplarily at least one of lithium metal, natural graphite, artificial graphite, or a silicon-based material including at least one of silicon, a silicon oxide compound, a silicon carbon compound, or a silicon alloy. The negative active material layer can further include a conductive agent and / or a binder. The conductive agent in the negative active material layer can exemplarily include at least one of carbon black, acetylene black, ketjen black, exfoliated graphite, graphene, carbon nanotube, carbon fiber, or carbon nanowire, and the binder in the negative active material layer can exemplarily include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, a polyacrylic acid salt, a polyacrylic acid ester, polyvinylpyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, styrene butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene.

[0060] In some exemplary embodiments, the separator film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. In particular, polyethylene and polypropylene have a good effect on preventing short circuits and can improve the stability of the electrode assembly through the shutdown effect. The thickness of the separator film 50 is in the range of about 3 μm to 500 μm.

[0061] As shown in FIG. 1, the second tab group 2 is disposed to be adjacent to the first tab group 1 in the first direction. The second tab group 2 is disposed to be spaced apart from the first tab group 1 in the second direction. Figure 3 As shown in FIG. 1, the second tab group 2 is disposed to be adjacent to the first tab group 1 in the first direction. The second tab group 2 is disposed to be spaced apart from the first tab group 1 in the second direction.

[0062] The second tab group 2 is disposed to be adjacent to the first tab group 1 in the first direction. The second tab group 2 is disposed to be spaced apart from the first tab group 1 in the second direction.

[0063] The second tab group 2 is disposed to be adjacent to the first tab group 1 in the first direction. The second tab group 2 is disposed to be spaced apart from the first tab group 1 in the second direction.

[0064] The shape of the recess 71 in the present embodiment can be circular as shown in FIG. 1, and can be square, diamond, long strip, oval, or other shapes, which is determined according to actual conditions. Figure 1 The shape of the recess 71 in the present embodiment can be circular as shown in FIG. 1, and can be square, diamond, long strip, oval, or other shapes, which is determined according to actual conditions.

[0065] The electrode core provided by the embodiment can increase the distance between the adjacent electrode pieces on both sides of the step in the first direction, make the distance between the adjacent electrode pieces at the step consistent, improve the consistency of the overall adhesion of the step battery, make the lithium ion transmission path consistent, meet the uniform distribution of lithium ions on the negative electrode piece 4 in the charging and discharging process, prevent excessive deposition of lithium ions in any area of the negative electrode piece 4, and further improve the interface morphology of the step battery.

[0066] On the other hand, the recess 71 on the first electrode piece can form a liquid storage groove for containing electrolyte, thereby improving the wettability of the electrolyte to the electrode piece, and further increasing the cycle life of the battery.

[0067] In one embodiment, the second electrode piece of the second electrode piece group 2 includes a concave-convex region and a non-concave-convex region, the non-concave-convex region is located on one side of the concave-convex region along the width direction of the second electrode piece; the projection of the non-concave-convex region in the thickness direction of the second electrode piece group 2 at least partially overlaps with the avoidance area 6 of the first electrode piece. In addition to improving the overall wettability of the second electrode piece group 2 to the electrolyte and improving the cycle life, the non-concave-convex region can effectively prevent the curling that easily occurs at the edge position during the hot pressing process, while ensuring the consistency of the overall adhesion of the second electrode piece group.

[0068] As shown in Figure 3 , in the first direction, the distance between the edge of the second electrode piece group 2 and the end of the avoidance area 6 away from the second electrode piece group 2 is a first distance L2, and the ratio of the first distance L2 to the length L1 of the avoidance area 6 in the first direction is in the range of: , so that the end of the second electrode piece group 2 in the first direction is located in the avoidance area 6.

[0069] The length L1 of the avoidance area 6 in the first direction is in the range of 2mm-10mm; the size of the first distance L2 is in the range of 0.4mm-8mm.

[0070] In the embodiment, the distance between the active material at the recess 71 and the other electrode piece in the position other than the avoidance area 6 is pulled apart, which can improve the wettability of the electrolyte in this area, and also make the adhesion around the step consistent with the adhesion at the step, thereby improving the consistency of the overall adhesion of the step battery.

[0071] In addition, the area of the first electrode piece can be S, the length of the first electrode piece in the first direction is L, the area of the avoidance area 6 is , and the ratio of the area of the avoidance area 6 to the area of the first electrode piece is in the range of: ; the ratio of the length of the avoidance area 6 in the first direction to the length of the first electrode piece in the first direction is in the range of: .

[0072] The area S of the first tab ranges from 100 mm 2 -12000 mm 2 The area of the avoidance area 6 ranges from 100 mm The area S of the first tab ranges from 100 mm 2 -1200 mm 2 .

[0073] In the specific embodiment, by limiting the ratio of the area of the avoidance area 6 to the area of the first tab and the ratio of the length of the avoidance area 6 in the first direction to the length of the first tab in the first direction, the area of the avoidance area 6 can be moderate, avoiding the problem that the edge of the second tab group 2 does not fall within the avoidance area 6, thereby failing to improve the adhesion consistency of the stepped battery. At the same time, it can also avoid the problem that the area of the avoidance area 6 is too large, resulting in inconsistent adhesion of the entire stepped battery.

[0074] Embodiment 3

[0075] As shown in Figure 4 , the edge of the concave-convex area 7 and one end of the first tab provided with the tab 5 has a first gap T1, and the edge of the concave-convex area 7 and the end of the second tab away from the tab 5 has a second gap T2; and the size of the first gap and the second gap in the second direction is smaller than the interval W1 of the two adjacent concave portions 71 in the second direction.

[0076] Figure 4 In the specific embodiment, the concave-convex area 7 is arranged in the first tab in the manner shown in , which can ensure that more concave portions 71 are arranged on the first tab, and the concave portions 71 can form a liquid storage groove to accommodate electrolyte when liquid injection, thereby improving the electrolyte infiltration of the tab, and further increasing the cycle life of the battery.

[0077] Figure 5 Of course, as shown in Figure 6 , the concave-convex area 7 can also completely cover one end of the first tab provided with the tab 5; the ceramic area 51 of the tab 5 used for connecting the first tab is provided with a concave portion 71, and the depth of the concave portion 71 in the tab 5 is less than the depth of the concave portion 71 in the first tab.

[0078] In the specific embodiment, the concave portion 71 falls on the edge of the first tab, which is more conducive to the infiltration of electrolyte when liquid injection; at the same time, the concave portion 71 can be connected to the ceramic area 51 of the tab 5 position in the first tab, and the depth of the concave portion 71 in the tab 5 is less than the depth of the concave portion 71 in the first tab, which can ensure that the tab 5 has sufficient strength to prevent the tab 5 from cracking.

[0079] As shown in Figure 6 , the size of the concave portion 71 at the tab 5 can be appropriately reduced to ensure that the tab 5 has sufficient strength.

[0080] As shown in Figure 7As shown, the first interval between the adjacent recesses 71 in the first direction is different, specifically, the first interval can be I1 or I2; and the ratio of the different first intervals ranges from 0.6 to 1.4, . The second interval between the adjacent recesses 71 in the second direction is different, and the second interval can be W1 or W2; and the ratio of the different second intervals ranges from 0.6 to 1.4, .

[0081] In the embodiment, the intervals between the adjacent recesses 71 in the first direction and the second direction are not limited to be the same, and in actual processing, the intervals between the adjacent recesses 71 do not need to be the same, which can effectively improve the die cutting efficiency and quality.

[0082] Embodiment 4

[0083] In actual processing, as shown, Figure 8 , the thickness of the position without the recess 71 in the first pole piece is h, the depth of the recess 71 is h2, the thickness of the position with the recess 71 in the first pole piece is h1, and the interval between the centers of the adjacent two recesses 71 is I1, which can make the depth of the recess 71 less than the thickness h of the position without the recess 71 in the first pole piece, and the side of the first pole piece away from the recess 71 is a plane.

[0084] When the side of the first pole piece away from the recess 71 is a plane, the thickness h of the position without the recess 71 in the first pole piece is the sum of the thickness h1 of the position with the recess 71 in the first pole piece and the depth h2 of the recess 71; when the side of the first pole piece away from the recess 71 is a protrusion, the thickness h of the position without the recess 71 in the first pole piece is less than the sum of the thickness h1 of the position with the recess 71 in the first pole piece and the depth h2 of the recess 71.

[0085] Further, the depth of the recess 71 in the first pole piece can be ; to ensure that the recess 71 of the first pole piece has sufficient depth, which can increase the wettability of the electrolyte, thereby increasing the cycle life of the battery. At the same time, it can improve the consistency of the overall adhesion of the step battery, and the lithium ion transport path tends to be consistent, which meets the uniform distribution of lithium ions on the negative pole piece 4 in the charging and discharging process, and prevents lithium precipitation during the cycle process.

[0086] Embodiment 5

[0087] As shown, Figure 9As shown, the thickness of the position without the recess 71 in the first tab is h, the thickness of the position with the recess 71 in the first tab is h4, the distance between the centers of two adjacent recesses 71 is I1, the side of the first tab away from the recess 71 is provided with a protrusion at the position corresponding to the recess 71, the height of the top end of the protrusion is h3, the height h3 of the protrusion is greater than or equal to the thickness of the position without the recess 71 in the first tab and less than 5 times the thickness of the position without the recess 71 in the first tab; .

[0088] The thickness of the position with the recess 71 in the first tab is less than or equal to the thickness of the position without the recess 71 in the first tab, .

[0089] The protrusion in the specific embodiment has a sufficient height, which can effectively improve the consistency of the overall adhesion of the stepped battery, and further improve the interface morphology; at the same time, the protrusion can prevent the rupture and reduce the energy density of the battery.

[0090] When the battery including the electric core provided in the present application is used, as Figure 10 shown, the horizontal axis is time and the vertical axis is adhesion, the adhesion change in the early stage of stretching is in the first box in the curve, and the adhesion change at the step of the battery is in the second box in the curve, it can be clearly seen from Figure 10 that by forming the recess 71 on the tab, the adhesion around the step of the first tab group 1 and the second tab group 2 and the adhesion at the step tend to be consistent while increasing the wettability of the electrolyte, thereby improving the consistency of the overall adhesion of the stepped battery. In addition, the lithium ion transmission path tends to be consistent, which meets the uniform distribution of lithium ions on the negative tab 4 in the charging and discharging process, thereby preventing the lithium precipitation of the battery.

[0091] Embodiment 6

[0092] On the basis of the above-mentioned embodiments, the first tab group 1 can include a first sub-tab located at the top layer, the first sub-tab includes a first current collector and a first active layer located on the surface of the first current collector close to the second tab group 2; the recess 71 is formed on the surface of the first sub-tab away from the first active layer.

[0093] In a specific example, the first sub-tab can be a single-sided tab, i.e., the surface of the first sub-tab away from the second tab group 2 is not provided with an active layer, thereby preventing the waste of raw materials, and at the same time, avoiding the risk of short circuit caused by the contact between the active layer away from the second tab group 2 and the inside of the shell.

[0094] In the embodiment, the recess 71 is formed on the side surface of the first sub-tab away from the first active layer, which can effectively increase the spacing between the first tab group 1 and the second tab group 2 at the recess 71, make the spacing between the adjacent tabs at the step consistent, improve the consistency of the overall adhesion of the step battery, make the lithium ion transmission path consistent, meet the uniform distribution of lithium ions on the negative tab during the charging and discharging process, prevent excessive deposition of lithium ions in any area of the negative tab, and further improve the interface morphology of the step battery.

[0095] In addition, the first tab of the first tab group 1 close to the second tab group 2 and the second tab of the second tab group 2 close to the first tab group 1 can be bonded. In one specific example, the first tab of the first tab group 1 close to the second tab group 2 and the second tab of the second tab group 2 close to the first tab group 1 are of the same polarity, for example, both are negative or positive, wherein the side surface of the first tab close to the second tab group is not coated with an active layer, the side surface of the second tab close to the first tab group is not coated with an active layer, and the two surfaces without active layer are bonded by glue or adhesive tape; in another example, the first tab of the first tab group 1 close to the second tab group 2 and the second tab of the second tab group 2 close to the first tab group 1 are of opposite polarity, and the two tabs are provided with a separator, and the first tab of the first tab group 1 close to the second tab group 2 and the second tab of the second tab group 2 close to the first tab group 1 are bonded by being combined with the separator.

[0096] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other. Any combination of all the embodiments provided in the present application is within the protection scope of the present application, which is not described here.

[0097] The above has introduced the battery cell provided by the present application in detail. The principles and implementation modes of the present application are described by applying specific examples in this paper, and the above embodiment description is only used to help understand the method and core idea of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. An electric cell, characterized by, The application relates to a battery electrode plate group, comprising: a first electrode plate group (1) comprising first electrode plates and separators; a second electrode plate group (2) comprising second electrode plates and separators; the first electrode plate group (1) and the second electrode plate group (2) are arranged in a stack, the size of the second electrode plate group (2) along the width direction of the second electrode plate group (2) is smaller than the size of the first electrode plate group (1) along the width direction of the first electrode plate group (1), and the whole of the first electrode plate group (1) and the second electrode plate group (2) arranged in the stack forms a step at at least one end; the first electrode plate of the first electrode plate group (1) is provided with a concave-convex area (7) and a clearance area (6); the concave-convex area (7) is provided with a plurality of concave parts (71), and the projection of the step along the thickness direction of the second electrode plate group (2) is located in the clearance area (6) of the first electrode plate group (1).

2. The electric cell of claim 1, wherein, In the first direction, the boundary of the clearance area (6) exceeds the projection of the step along the thickness direction of the second electrode plate group (2) in the first electrode plate group (1); and / or; the clearance area (6) is located on the electrode plate of the second electrode plate group (2) close to the first electrode plate group (1); and / or, one side of the first electrode plate away from the concave part (71) is provided with a protrusion at the position corresponding to the concave part (71), and / or the second electrode plate of the second electrode plate group (2) comprises a concave-convex area and a non-concave-convex area, and the non-concave-convex area is located on one side of the concave-convex area along the width direction of the second electrode plate; the projection of the non-concave-convex area along the thickness direction of the second electrode plate group (2) at least partially overlaps with the clearance area (6) of the first electrode plate.

3. The electric cell of claim 2, wherein, In the first direction, the edge of the second pole piece group (2) is away from one end of the second pole piece group (2) in the avoidance area (6) by a first distance L2, and the ratio of the first distance L2 to the length L1 of the avoidance area (6) in the first direction is in the range of: .

4. The cell of claim 3, wherein, The length L1 of the clearance area (6) in the first direction ranges from 2 mm to 10 mm; and / or; the size of the first distance L2 ranges from 0.4 mm to 8 mm.

5. The electric cell of claim 4, wherein, The area of the first pole piece is S, the length of the first pole piece in the first direction is L, the area of the avoidance zone (6) is ; The ratio of the area of the avoidance zone (6) to the area of the first pole piece is in the range of: ; And / or, the ratio of the length of the first direction of the avoidance zone (6) to the length of the first direction of the first pole piece is in the range of: ; And / or; The area S of the first pole piece ranges from 100 mm 2 - 12000 mm 2 ; and / or; The area of the avoidance zone (6) ranging from 100 mm 2 -1200 mm 2 .

6. The electric cell of claim 1, wherein, the edge of the concave-convex area (7) has a first gap T1 with one end of the first electrode plate provided with a tab (5), and the edge of the concave-convex area (7) has a second gap T2 with one end of the second electrode plate away from the tab (5); the size of the first gap T1 and / or the second gap T2 along the second direction is smaller than the interval W1 of two adjacent concave parts (71) along the second direction.

7. The electric cell of claim 1, wherein, In the second direction, the first electrode plate comprises a tab (5) and a ceramic area (51) located on the tab (5); the ceramic area (51) of the tab (5) is provided with the concave part (71).

8. The electric cell of claim 7, wherein, The thickness of the position in the first pole piece where the recess (71) is not provided is h, the depth of the recess (71) is h2, the thickness of the position in the first pole piece where the recess (71) is provided is hi, and .

9. The electric cell of claim 1, wherein, The first electrode plate group (1) comprises a first sub-electrode plate located on the top layer, and the first sub-electrode plate comprises a first current collector and a first active layer located on the surface of the first current collector close to the second electrode plate group (2); the concave part (71) is formed on the surface of the first sub-electrode plate away from the first active layer.

10. The electric cell of claim 1, wherein, The first electrode plate of the first electrode plate group (1) close to the second electrode plate group (2) and the second electrode plate of the second electrode plate group (2) close to the first electrode plate group (1) are bonded.

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