Battery cell and battery

Abstract

The utility model provides a battery cell and a battery, the battery cell comprises a first pole piece, a second pole piece and diaphragms which are arranged in a laminated winding manner, and the diaphragms are arranged between the first pole piece and the second pole piece at intervals; the first pole piece comprises a first current collector and a first active material layer arranged on the first current collector, a tab groove is formed in the first active material layer, and a tab is connected in the tab groove; the first pole piece comprises a first straight section located on the innermost ring of the battery cell, the first pole piece is provided with a concave-convex structure, the concave-convex structure comprises a plurality of protrusions arranged at intervals and pits opposite to the protrusions, and at least part of the protrusions and the pits are located on the first straight section; the ratio of the area S1 of the concave-convex structure to the area S2 of the first straight section is 20% < = S1 / S2 < = 60%. The technical problem of poor coverage of the positive and negative plates and the diaphragm is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a battery field especially relates to a battery cell and battery. BACKGROUND

[0002] With the rapid development of lithium ion battery technology, lithium ion batteries have been widely used in various fields, such as electronic device field, aerospace field, etc., and people's requirements for lithium ion batteries are also getting higher and higher, especially the improvement of the cycle life and safety performance of lithium ion batteries is more urgent.

[0003] At present, the development and innovation of the production material end of the battery are difficult to break through, and the related enterprises are committed to optimizing the structure of the battery to improve the cycle life and safety performance of the lithium ion battery. In the battery production process, the positive plate, the negative plate and the diaphragm for isolating the positive plate and the negative plate are needed, and the diaphragm needs to completely cover the negative plate, and the negative plate needs to completely cover the positive plate, but during the entering of the plate, the plate is easy to slide, which leads to poor coverage of the positive and negative diaphragm, and even causes the problem of plate folding, which affects the cycle life and use safety of the battery.

[0004] Therefore, it is urgent to solve the technical problem that the plate is easy to slide and leads to poor coverage of the positive and negative diaphragm. UTILITY MODEL CONTENT

[0005] The utility model provides a kind of battery cell and battery to solve the technical problem that the plate is easy to slide and leads to poor coverage of the positive and negative diaphragm.

[0006] In order to achieve the above purpose, the utility model provides a kind of battery cell, which comprises a first plate, a second plate and a diaphragm arranged in a stacked and wound manner, the diaphragm is arranged between the first plate and the second plate;

[0007] The first plate comprises a first current collector and a first active material layer arranged on the first current collector, an ear slot is formed in the first active material layer, the first current collector is exposed from the ear slot, and an ear is connected in the ear slot.

[0008] The first plate comprises a first flat section located in the innermost circle of the battery cell, the first plate is provided with a concave-convex structure, the concave-convex structure comprises a plurality of convexities arranged at intervals and concave pits arranged opposite to the convexities, at least part of the convexities and the concave pits are located in the first flat section.

[0009] The second plate comprises a second current collector and a second active material layer arranged on the second current collector, the second active material layer is provided with a plurality of grooves, the surface where the concave pits of the first plate are located and the surface where the grooves are located are arranged opposite to each other.

[0010] The ratio of the area S1 of the concave-convex structure to the area S2 of the first flat section is 20%≤S1 / S2≤60%.

[0011] The electric core provided by the utility model, through setting the concave-convex structure on the first pole piece, the concave-convex structure includes multiple protrusions arranged at intervals and pits arranged opposite to the protrusions, at least part of the protrusions and the pits are located on the first flat section, the planar roughness of the first flat section can be effectively improved, the contact area of the first flat section and other components is increased during battery production, the friction of the surface of the first flat section in the inner circle of the electric core is improved, the first pole piece is prevented from sliding, wrinkling and folding when entering the piece, thereby the safety of the battery is improved, meanwhile, the first flat section can be better attached to the diaphragm, the contact area is increased, and the possibility of sliding is reduced, the stress on the first flat section during the winding process can be prevented from being too large, and the stress of the first flat section is effectively dispersed.

[0012] The second active material layer of the second pole piece is provided with multiple grooves, the surface where the pits of the first pole piece are located and the surface where the grooves are located are arranged opposite to each other, that is, the grooves of the second pole piece can be located in the innermost circle of the electric core, the grooves are opposite to the pits of the first pole piece, thereby the friction of the head of the second pole piece is improved, the second pole piece can be better attached to the diaphragm, the contact area is increased, when the positive pole piece, the diaphragm and the negative pole piece enter the piece and are wound, the three can be effectively bonded and wound together, the winding efficiency is improved, meanwhile, the positive pole piece and the diaphragm are better attached, and the diaphragm in the head of the innermost circle of the electric core can also be prevented from moving when the winding is completed and the winding needle for fixing the diaphragm is extracted.

[0013] In addition, in the application, the ratio of the area S1 of the concave-convex structure 30 to the area S2 of the first flat section is 20%≤S1 / S2≤60%. If the ratio of S1 / S2 is too small, the friction of the surface of the first flat section and the improvement of the supporting effect of the first pole piece are not obvious, on the contrary, if the ratio of S1 / S2 is too large, the concave-convex structure occupies too large an area of the first pole piece, the first active material layer on the first pole piece is easy to fall off in the process of processing the concave-convex structure, that is, the problem of powder falling occurs, the falling first active material layer is easy to cause the problem of short circuit of the electric core, and the safety of the battery is not conducive to guarantee.

[0014] In a possible implementation manner, the first pole piece includes a double-sided coating area where the first active material layer is arranged on both surfaces of the first current collector, and the first flat section is located in the double-sided coating area, and the protrusions protrude from the surface of the double-sided coating area.

[0015] In a possible implementation manner, the openings of at least part of the pits are towards the center position of the electric core.

[0016] In a possible implementation, the height H1 of the concave-convex structure protruding from the first active material layer, the thickness H2 of the first active material layer in the double-sided coating area, and the thickness H3 of the first current collector satisfy: 0.1xH2-0.8xH3≤H1≤0.8xH2-0.8xH3.

[0017] In a possible implementation, along the length direction of the first pole piece:

[0018] The length L1 of the first flat section satisfies: 4mm≤L1≤100mm; and / or,

[0019] The first flat section has a first side, and the spacing L2 between the concave-convex structure and the first side satisfies: 1mm≤L2≤5mm.

[0020] In a possible implementation, along the width direction of the first pole piece:

[0021] The spacing T1 between the concave-convex structure and the edge of the first active material layer is 5% T2≤T1≤45% T2.

[0022] In a possible implementation, the double-sided coating area further includes a first bending section and a second flat section, and the first flat section, the first bending section, and the second flat section are sequentially connected along the length direction of the first pole piece.

[0023] One end of the concave-convex structure away from the first side is a cutoff end, and the cutoff end is located in the first flat section or the first bending section or the second flat section.

[0024] In a possible implementation, the protrusions are rhombuses; and / or,

[0025] The included angle θ between two adjacent sides of the rhombus satisfies: 20°<θ<90°; and / or,

[0026] The side length a of the rhombus satisfies: 2mm≤a≤8mm; and / or,

[0027] The spacing b between two adjacent protrusions satisfies: 0.5mm≤b≤3mm.

[0028] In a possible implementation, the protrusions are circles, the circumcircle diameter D of the protrusions satisfies: 0.3mm≤D≤8mm, and / or, the projections of two adjacent protrusions on the plane where the first pole piece is located do not coincide.

[0029] In a possible implementation, the distance c between the centers of the circumcircle of the plane where the first pole piece is located and the two adjacent protrusions satisfies 1mm<=c<=6mm.

[0030] In a possible implementation, the protrusions are linear.

[0031] The width e of the protrusions satisfies 1mm<=e<=8mm; and / or,

[0032] The distance f between the two adjacent protrusions satisfies 2mm<=f<=10mm.

[0033] In a possible implementation, the height H1 of the protrusion of the concave-convex structure from the first active material layer satisfies 2um<=H1<=80um.

[0034] In a possible implementation, the first pole piece further comprises a single-side coating area provided with the first active material layer on one side, and a blank foil area not provided with the first active material layer on both sides, and the double-side coating area, the single-side coating area and the blank foil area are sequentially connected along the length direction of the first pole piece.

[0035] In a possible implementation, in the thickness direction of the battery cell, the projection of the concave-convex structure at least partially overlaps with the tab.

[0036] The utility model further provides a kind of battery comprising above-mentioned battery cell.

[0037] In the utility model, the first pole piece is a positive pole piece, and the second pole piece is a negative pole piece, by being provided with concave-convex structure on the first pole piece, the surface roughness of the positive pole piece can be effectively increased, the anti-skid performance of the positive pole piece is improved, and the problem that the positive pole piece in battery cell is easy to slide and fold is improved.

[0038] The utility model provides a kind of battery cell and battery, by controlling the height H1 of the protrusion of the concave-convex structure from the first active material layer, the thickness H2 of the first active material layer in the double-side coating area and the thickness H3 of the first current collector, three satisfy: 0.1xH2-0.8xH3<=H1<=0.8xH2-0.8xH3, the height H1 of the protrusion of the concave-convex structure from the first active material layer can be effectively controlled, so that the thickness of protrusion, the thickness of the first current collector and the thickness of the first active material layer are matched, prevent H1 too big from being pressed broken at the position corresponding to positive pole piece when processing concave-convex structure, thereby prevent causing positive pole piece fracture, short circuit and other safety problems.

[0039] The utility model provides a kind of battery cell and battery, by the edge between the concave-convex structure and the edge of double-side coating area with certain spacing, can prevent the edge of positive pole piece from falling powder when processing concave-convex structure.

[0040] In addition to the technical problems solved by the embodiments of the utility model described above, the technical features constituting the technical solutions and the beneficial effects brought by these technical features, other technical problems solved by the embodiments of the utility model, other technical features included in the technical solutions and the beneficial effects brought by these technical features will be further described in detail in the specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are some embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0042] Figure 1 The structural schematic diagram of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0043] Figure 2 The structural schematic diagram of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0044] Figure 3 The sectional view of the concave-convex structure of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0045] Figure 4 The top view of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0046] Figure 5 The bottom view of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0047] Figure 6 The top view of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0048] Figure 7 The bottom view of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0049] Figure 8 The partial structure enlarged view of the battery cell is shown in the figure. Figure 7 The partial structure enlarged view of the battery cell is shown in the figure.

[0050] Figure 9 The top view of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0051] Figure 10 The bottom view of the first pole piece of the battery cell provided by the embodiments of the utility model is shown in the figure.

[0052] Reference numerals:

[0053] 10 - first current collector;

[0054] 11 - single-coated area;

[0055] 12 - empty foil area;

[0056] 20 - first active material layer;

[0057] 30 - concave-convex structure;

[0058] 31 - protrusion;

[0059] 311 - pit;

[0060] 32 - cut-off end;

[0061] 40 - double-coated area;

[0062] 41 - first straight section;

[0063] 411 - first side;

[0064] 42 - first bent section;

[0065] 43 - second straight section;

[0066] 44 - tab slot;

[0067] 50 - first tab;

[0068] 60 - second tab;

[0069] 70 - diaphragm;

[0070] 80 - tab. DETAILED DESCRIPTION

[0071] To make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some 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.

[0072] In the winding core structure of the winding type lithium ion battery, the positive tab usually has a double-coated area, a single-coated area and an empty foil area. The double-coated area is on the inner side of the winding core, and the first end of the double-coated area is the starting end of the winding core, i.e. the starting end of the positive tab.

[0073] The pole piece used in the winding core is usually a long sheet structure. The longer the pole piece is, the more active substances can be coated on the surface, which can improve the capacity of the winding core. The long pole piece can also prevent the problems of excessive cycle expansion and capacity attenuation caused by excessive rebound of the pole piece. When the pole piece forms the winding core, the double-coated area in the positive pole piece is stacked with the separator and the negative pole piece to form the starting end of the winding core winding at the beginning of the winding core winding. After the pole piece is wound, the bending occurs along the thickness direction of the winding core, and the plurality of flat sections are arranged in parallel.

[0074] Because the surface of the positive pole piece is relatively smooth after the positive pole piece is coated with the positive active material layer slurry in the processing process, dried and rolled, the first flat section located in the innermost circle of the winding core is subjected to the bending and extrusion force in the process of forming the winding core. The pole piece is prone to sliding and wrinkling, which leads to poor coverage of the positive and negative separators, and the problems of contact between the positive and negative electrodes and short circuit. In addition, the positive pole piece has relatively large hardness and poor toughness. The positive pole piece is prone to extrusion folding, breaking and other problems when the pole piece is inserted. The gap between the pole pieces is abnormal, which leads to the problems of poor contact interface of the pole pieces and black spots and even lithium precipitation after the cycle, and affects the safety of the battery.

[0075] The winding core and the battery provided in the embodiments of the present application are described below with reference to the accompanying drawings.

[0076] Reference Figure 1 and Figure 2 As shown in FIGS. 1 and 2, the utility model provides a kind of winding core, including the first pole piece 50, second pole piece 60 and separator 70 of laminated winding arrangement, separator 70 is spaced apart between first pole piece 50 and second pole piece 60;First pole piece 50 includes first current collector 10 and first active material layer 20 arranged on first current collector 10, first active material layer 20 is provided with tab slot 44, first current collector 10 is exposed from tab slot 44, and tab 80 is connected in tab slot 44.

[0077] First pole piece 50 includes first flat section 41 in the innermost circle of winding core, and first pole piece 50 is provided with concave-convex structure 30, as shown in FIGS. 1 and 2, concave-convex structure 30 includes a plurality of convex 31 spaced apart and recess 311 arranged opposite to convex 31, and at least part of convex 31 and recess 311 are located in first flat section 41. Figure 3 and Figure 4 As shown in FIGS. 1 and 2, concave-convex structure 30 includes a plurality of convex 31 spaced apart and recess 311 arranged opposite to convex 31, and at least part of convex 31 and recess 311 are located in first flat section 41.

[0078] Second pole piece 60 includes second current collector and second active material layer arranged on second current collector, and second active material layer is provided with a plurality of grooves, and the surface where recess 311 of first pole piece 50 is located is arranged opposite to the surface where groove is located.

[0079] The utility model provides a kind of electric core, first pole piece 50 is provided with concave-convex structure 30, first pole piece 50 can be positive pole piece, second pole piece 60 is negative pole piece, at least part concave-convex structure 30 is located first flat section 41, the area S1 of concave-convex structure 30 accounts for the ratio of the area S2 of first flat section 41:20%≤S1 / S2≤60%, can effectively promote the plane roughness of first flat section 41, when battery production, promote the friction of the surface of first flat section 41, prevent the effect of sliding, wrinkling and folding when positive pole piece enters piece, to reduce the abnormal gap between pole piece to cause the problem such as contact interface deterioration, lithium precipitation, also help to guarantee that diaphragm 70 completely covers negative pole piece, negative pole piece completely covers positive pole piece, to improve the security of battery, simultaneously, first flat section 41 can be better adhered to diaphragm, increase contact area, reduce the possibility of sliding, can prevent the stress that the first flat section 41 of positive pole piece is subjected to during winding process is too large, effectively disperses the stress of first flat section 41.

[0080] Second active material layer of second pole piece 60 is provided with a plurality of grooves, the surface where the recess 311 of first pole piece 50 is located and the surface where groove is located are oppositely arranged, i.e. the groove of second pole piece can be located in the innermost circle of electric core, the groove and recess 311 of first pole piece are oppositely arranged, to improve the friction of the head of negative pole piece, so that second pole piece can better adhere to diaphragm, increase contact area, when positive pole piece, diaphragm and negative pole piece enter piece and wind, three can be effectively adhered together and wind, improve winding efficiency, simultaneously, positive pole piece and diaphragm better adhere, also can prevent the diaphragm of head from moving when fixing diaphragm winding needle is extracted after winding is completed.

[0081] The area S1 of concave-convex structure 30 accounts for the ratio of the area S2 of first flat section 41:20%≤S1 / S2≤60%.If the ratio of S1 / S2 is too small, the friction of the surface of first flat section 41 and the support effect of first pole piece 50 are not obvious;Conversely, if the ratio of S1 / S2 is too large, the area of concave-convex structure 30 on first pole piece 50 is too large, easy to cause the first active material layer 20 on first pole piece 50 to fall off in the process of processing concave-convex structure 30, that is, the problem of powder falling, the first active material layer 20 that falls off is easy to cause the problem of electric core short circuit, is not conducive to guarantee the security of battery.

[0082] In a possible implementation, the ratio of the area S1 of the concave-convex structure 30 to the area S2 of the first flat section 41 is S1 / S2, where S1 / S2 can be 20%, 25%, 30%, 36%, 40%, 43%, 50%, 57%, or 60%. This can effectively increase the friction of the surface of the first flat section 41 and improve the adhesion of the first pole piece 50, and can also leave a certain space between the edge position of the first pole piece 50 and the edge position of the concave-convex structure 30 to prevent the problem of powder falling at the edge position of the first pole piece 50.

[0083] In a possible implementation, the concave-convex structure 30 includes, but is not limited to, shapes such as a rhombus, a circle, a waist shape, an ellipse, and the like, and can also be in a patterned shape and the like.

[0084] In a possible implementation, the first pole piece 50 includes a double-coated area 40 in which the first active material layer 20 is arranged on both surfaces of the first current collector 10, the first flat section 41 is located in the double-coated area 40, and the concave-convex structure 30 is formed in the double-coated area 40. The double-layer arrangement of the first active material layer can effectively increase the overall energy density, and the first flat section with the first active material layer on both surfaces can uniformly disperse the pressure of the roller during embossing, so that the forces on both sides are uniform.

[0085] In a possible implementation, the protrusion 31 protrudes from the surface of the double-coated area 40, the concave pit 311 is formed in the protrusion 31, the opening of the concave pit 311 faces away from the protruding direction of the protrusion 31, and the concave-convex structure 30 can be a pattern structure formed by rolling.

[0086] Since the protrusion 31 protrudes from the surface of the double-coated area 40, the position where the concave-convex structure 30 is arranged in the double-coated area 40 is no longer a smooth plane, thereby increasing the anti-skid friction of the first pole piece 50 and preventing the positive pole piece from sliding, wrinkling, and folding when the positive pole piece is inserted.

[0087] In a possible implementation, the plurality of protrusions 31 can be arranged in a plurality of rows and a plurality of columns, and the plurality of protrusions 31 can also be arranged in a circular ring shape.

[0088] In a possible implementation, in the concave-convex structure 30, the protruding directions of all the protrusions 31 can be consistent, or the protruding directions of a part of the plurality of protrusions 31 can be consistent, and the protruding directions of the other part of the plurality of protrusions 31 can be opposite to the protruding directions of the part of the plurality of protrusions 31, which is not limited here.

[0089] In a possible implementation, in the preparation of the roll core, the openings of the concave pits 311 all face away from the center position of the roll core, which can also prevent the positive pole piece from sliding, wrinkling, and folding when the positive pole piece is inserted.

[0090] In one possible implementation, at least part of the opening of the recess 311 faces the center of the core. This structure, because the recess 311 can hold and store some electrolyte, allows the core to store more electrolyte, which helps improve battery efficiency and ensures normal cell cycling.

[0091] In one possible implementation, during the fabrication of the core, the openings of all the recesses 311 are oriented towards the center of the core. This maximizes the amount of electrolyte that can be stored within the recesses 311, thereby improving battery efficiency.

[0092] In one possible implementation method, refer to Figure 3 As shown, the height H1 of the protrusion of the concave-convex structure 30 from the first active material layer 20, the thickness H2 of the first active material layer 20 located in the double-sided coating area 40, and the thickness H3 of the first current collector 10 satisfy the following condition: 0.1×H2-0.8×H3≤H1≤0.8×H2-0.8×H3. The aim is to improve the slippage and wrinkling of the electrode in the battery cell while ensuring that the thickness of the protrusion, the thickness of the first current collector, and the thickness of the first active material layer are matched. It also aims to prevent the electrode from being crushed during the processing of the concave-convex structure, avoiding new problems such as electrode breakage, lithium plating, and short circuits.

[0093] In one possible implementation, H1 can be, for example: 0.1×H2-0.8×H3, or 0.2×H2-0.8×H3, or 0.3×H2-0.8×H3, or 0.4×H2-0.8×H3, or 0.5×H2-0.8×H3, or 0.6×H2-0.8×H3, or 0.7×H2-0.8×H3, or 0.8×H2-0.8×H3.

[0094] If H1 > 0.8 × H2 - 0.8 × H3, it means that the height of the protrusion of the concave-convex structure 30 from the first active material layer 20 is too high, which may cause the corresponding position of the positive electrode to be crushed during the processing of the concave-convex structure, resulting in electrode damage, breakage or lithium plating, affecting the safety of use; if H1 < 0.1 × H2 - 0.8 × H3, it means that the height of the protrusion of the concave-convex structure 30 from the first active material layer 20 is too small, which will make the improvement of the anti-slip effect of the double-sided coating area 40 not obvious.

[0095] In the process of forming the concave-convex structure 30, the first current collector 10 and the first active material layer 20 are deformed together, so that the protruding height H1 of the concave-convex structure 30 from the first active material layer 20 is affected by the thickness H2 of the first active material layer 20 in the double-coated area 40 and the thickness H3 of the first current collector 10. By matching the three through the above relationship, the tab can be prevented from being crushed in the process of forming the concave-convex structure, and new problems such as tab fracture, lithium precipitation, short circuit, and other safety problems can be avoided.

[0096] In one possible implementation, as shown in Figure 3 the height H1 of the concave-convex structure 30 from the first active material layer 20 satisfies 2 μm≤H1≤80 μm. This helps to stabilize the spacing between the first flat section 41 of the first tab 50 and other adjacent components.

[0097] In one possible implementation, the height H1 of the concave-convex structure 30 from the first active material layer 20 may, for example, be 2 μm, 10 μm, 20 μm, 30 μm, 40 μm, 45 μm, 50 μm, 60 μm, 70 μm, or 80 μm.

[0098] In one possible implementation, as shown in Figure 4 the length L1 of the first flat section 41 along the length direction of the first tab 50 satisfies 4 mm≤L1≤100 mm. This facilitates reducing the thickness of the core when the first tab 50 is processed into a core, thereby reducing the thickness of the battery, making the battery suitable for some thin and light products, and expanding the application range of the battery; at the same time, it ensures that the concave-convex structure on the first flat section has sufficient size to ensure its friction.

[0099] In one possible implementation, the length L1 of the first flat section 41 along the length direction of the first tab 50 may, for example, be 4 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, or 100 mm.

[0100] In one possible implementation, as shown in Figure 4 the spacing L2 between the first flat section 41 and the concave-convex structure 30 along the length direction of the first tab 50 satisfies 1 mm≤L2≤5 mm. The first edge 411 is located at one end of the length direction of the double-coated area 40, and the first edge 411 is the starting position of winding when the first tab 50 is processed into a core.

[0101] In a possible implementation, the distance L2 between the concave-convex structure 30 and the first edge 411 along the length direction of the first pole piece 50 can be, for example, 1 mm, 1.5 mm, 2 mm, 2.2 mm, 2.6 mm, 3 mm, 4 mm, or 5 mm.

[0102] This is because, when processing the concave-convex structure 30, a certain pressure needs to be applied to the first pole piece 50. If the distance L2 is too small, it means that the distance between the concave-convex structure 30 and the first edge 411 is too close. After a certain pressure is applied to the first pole piece 50 when processing the concave-convex structure 30, the first active material layer 20 near the first edge 411 is prone to falling off, that is, the problem of powder falling occurs. Conversely, if the distance L2 is too large, it means that the distance between the concave-convex structure 30 and the first edge 411 is too far, which reduces the arrangement area of the concave-convex structure 30 and is not conducive to improving the slip resistance of the first pole piece 50.

[0103] The present application satisfies 1 mm≤L2≤5 mm through the distance L2, so that the concave-convex structure 30 and the first edge 411 have a sufficient distance, avoiding the problem that the first edge 411 near the first active material layer 20 falls off when processing the concave-convex structure 30. In addition, the area of the concave-convex structure 30 is not too small, which ensures the significant improvement effect of the slip resistance.

[0104] In a possible implementation, as shown in FIG. 5, along the width direction of the first pole piece 50, the distance between the concave-convex structure 30 and the edge of the first active material layer 20 is T1, and the width of the first active material layer 20 is T2, where 5%T2≤T1≤45%T2. Figure 5 Such a structure makes the edge of the concave-convex structure 30 and the edge of the first active material layer 20 have a certain distance T1, which aims to prevent the distance T1 from being too small, causing the edge of the first pole piece 50 to fall off when processing the concave-convex structure 30, and also aims to prevent the distance T1 from being too large, causing the area of the concave-convex structure 30 to be insufficient to significantly improve the slip resistance of the first flat section 41, so that the first pole piece 50 has good comprehensive performance.

[0105] In a possible implementation, T1 can be, for example, 5%T2, 10%T2, 15%T2, 20%T2, 25%T2, 30%T2, 34%T2, 40%T2, or 45%T2.

[0106] In a possible implementation, as shown in FIG. 5, along the width direction of the first pole piece 50, the distance between the concave-convex structure 30 and the edge of the first active material layer 20 is T1, and the width of the first active material layer 20 is T2, where 5%T2≤T1≤45%T2. Figure 4As shown, the double-coated area 40 further comprises a first bending section 42 and a second straight section 43, the first straight section 41, the first bending section 42 and the second straight section 43 are sequentially connected along the length direction of the first pole piece 50; one end of the concave-convex structure 30 away from the first edge 411 is a cut-off end 32, the cut-off end 32 is located in the first straight section 41 or the first bending section 42 or the second straight section 43.

[0107] The position of the cut-off end 32 is not specifically limited here, the cut-off end 32 can coincide with one end of the first straight section 41 away from the first edge 411, the cut-off end 32 can also have a spacing greater than 1mm between one end of the first straight section 41 away from the first edge 411, for example, the cut-off end 32 is located in the first bending section 42 or the second straight section 43, in the embodiment that the cut-off end 32 is located in the first bending section 42, that is, the concave-convex structure is also on the first bending section 42, it can be understood that the first bending section 42 will be subjected to excessive bending stress compared to the first straight section 41 or the second straight section 43, and the concave-convex structure can effectively improve the deformation ability of the pole piece, thereby preventing the first bending section 42 from breaking due to excessive stress.

[0108] In a possible implementation, when the pole piece is processed into a roll core, a plurality of straight sections are arranged in parallel along the thickness direction of the roll core. For example, when the pole piece is processed into a roll core, the double-coated area 40 can further comprise a third straight section, a fourth straight section, an Nth straight section, etc., where N is a natural number, each two adjacent straight sections are connected by a bending section, and the straight section located at the centermost position of the roll core is the first straight section 41, wherein the first straight section 41, the second straight section 43, the third straight section, the fourth straight section, and the Nth straight section are substantially parallel.

[0109] In a possible implementation, referring to Figure 6 , Figure 7 and Figure 8 As shown, the protrusion 31 is in the shape of a rhombus, the included angle θ between two adjacent sides of the rhombus satisfies 20°<θ<90°, the side length a of the rhombus satisfies 2mm≤a≤8mm, and the spacing b between two adjacent protrusions 31 satisfies 0.5mm≤b≤3mm. Such a structure makes the protrusion 31 in the concave-convex structure 30 in the shape of a rhombus have better stability and supportability.

[0110] When the spacing b between the two adjacent protrusions 31 is less than 0.5, the spacing between the two adjacent protrusions 31 is too small, and the protrusions 31 are prone to overlap during the process of processing the protrusions 31, or the local stress of the double-sided coating area 40 is too large, causing the first pole piece 50 to break; when the spacing between the two adjacent protrusions 31 is greater than 3 mm, the span between the two adjacent protrusions 31 is too large, and the protrusions 31 cannot effectively improve the roughness of the double-sided coating area 40, and it is difficult to effectively improve the problem that the double-sided coating area 40 of the first pole piece 50 is prone to sliding.

[0111] Therefore, in the present application, by satisfying 0.5 mm≤b≤3 mm for the spacing b between the two adjacent protrusions 31, the problems of overlap between the two adjacent protrusions 31, the local stress of the double-sided coating area 40 being too large to cause the first pole piece 50 to break, and the double-sided coating area 40 of the first pole piece 50 being prone to sliding can be effectively improved, thereby helping to ensure that the positive and negative pole pieces are in the correct position during the process of preparing the core.

[0112] The two adjacent angles in the rhombus are complementary, that is, the sum of the two adjacent angles in the rhombus is 180°.

[0113] If the angle θ between the two adjacent sides in the rhombus is too small, the edge of the protrusion 31 will be too sharp, and in the present application, the angle θ between the two adjacent sides in the rhombus satisfies 20°<θ<90°, which can avoid the edge of the protrusion 31 being too sharp, thereby avoiding piercing the first pole piece 50 to affect the service life of the first pole piece 50.

[0114] In a possible implementation, the angle between the two adjacent sides in the rhombus is a rounded angle instead of a sharp angle, which prevents the first active material layer 20 from being damaged or the first current collector 10 from being pierced due to the hard and sharp angle, resulting in damage to the first pole piece 50, and in the present application, the angle between the two adjacent sides in the protrusion 31 of the rhombus is a rounded angle, and the radius of the rounded angle is 1 mm, which is to prevent the angle between the two adjacent sides from being too sharp, thereby helping to avoid damaging the first active material layer 20 or piercing the first current collector 10, and ensuring the service life of the first pole piece 50.

[0115] In a possible implementation, the angle θ between the two adjacent sides in the rhombus may, for example, be 25°, 30°, 45°, 60°, 75°, 80°, etc.

[0116] In a possible implementation, the side length a of the rhombus may, for example, be 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 5.5 mm, 6 mm, 7 mm, or 8 mm.

[0117] In a possible implementation, the spacing b between two adjacent protrusions 31 can be, for example, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm.

[0118] In a possible implementation, the spacing b between two adjacent protrusions 31 can be, for example, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm. Figure 4 and Figure 5 As shown in FIG. 6, the protrusions 31 are circular, the diameter D of the circumscribed circle of the protrusions 31 satisfies 0.3 mm≤D≤8 mm, the projections of two adjacent protrusions 31 on the plane where the first tab 50 is located do not coincide, and the distance c between the centers of the circumscribed circles of two adjacent protrusions 31 on the plane where the first tab 50 is located satisfies 1 mm≤c≤6 mm. Such a structure makes the protrusions 31 in the concave-convex structure 30 circular, which has good stability and support, and avoids the problem that the protrusions 31 collapse and affect the storage of electrolyte in the pits 311.

[0119] When the diameter D of the circumscribed circle is too small, a sharp end effect is easily caused, which leads to damage of the first tab 50. When the diameter D of the circumscribed circle is too large, the edge span of the protrusions 31 is too large, which is not conducive to effectively supporting between the positive and negative tabs, and the protrusions 31 are prone to collapse, which affects the improvement of the anti-skid performance of the tab. In this application, by controlling 0.3 mm≤D≤8 mm, the protrusions 31 have good support, which also helps to prevent the problem of causing a sharp end effect leading to damage of the tab, and improves the safety of the battery in use.

[0120] When the distance c between the centers of the circumscribed circles of two adjacent protrusions 31 on the plane where the first tab 50 is located is too small, the two adjacent protrusions 31 are easily overlapped, which leads to damage of the first tab 50. When the distance c between the centers of the circumscribed circles of two adjacent protrusions 31 on the plane where the first tab 50 is located is too large, the two adjacent protrusions 31 cannot provide stable support, and it is not conducive to greatly improving the anti-skid effect of the double-sided coating area 40. By controlling 1 mm≤c≤6 mm, the problem of the two adjacent protrusions 31 overlapping to cause damage of the first tab 50 can be effectively reduced, and the anti-skid effect of the double-sided coating area 40 is greatly improved.

[0121] In a possible implementation, the diameter D of the circumscribed circle of the protrusions 31 can be, for example, 1 mm≤D≤3 mm.

[0122] In a possible implementation, the diameter D of the circumscribed circle of the protrusions 31 can be, for example, 0.3 mm, 1 mm, 1.3 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 5.5 mm, 6 mm, 7 mm, or 8 mm.

[0123] In one possible implementation, the distance c between the centers of the circumcircle of the plane containing the first pole piece 50 of two adjacent protrusions 31 can be, for example, 1.5 mm ≤ c ≤ 4 mm.

[0124] In one possible implementation, the distance c between the centers of the circumcircle of two adjacent protrusions 31 in the plane containing the first pole piece 50 can be, for example, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 5.5 mm, or 6 mm.

[0125] In one possible implementation method, refer to Figure 9 and Figure 10 As shown, the protrusion 31 is linear, and the width e of the protrusion 31 satisfies 1mm≤e≤8mm. The distance f between two adjacent protrusions 31 satisfies 2mm≤f≤10mm.

[0126] In this example, when the width e of the protrusion 31 is less than 1 mm, it not only increases the processing difficulty of the protrusion 31 but also easily causes damage to the first electrode 50. When the width e of the protrusion 31 is greater than 8 mm, it affects the supporting strength of the protrusion 31 itself, making it prone to collapse and hindering the provision of a stable anti-slip effect. Therefore, in this application, the width e of the protrusion 31 is made to satisfy 1 mm ≤ e ≤ 8 mm, which can reduce the problem of damage to the first electrode 50 while ensuring the supporting strength of the protrusion 31 itself.

[0127] When the spacing f is less than 2mm, the spacing f between two adjacent protrusions 31 is too small, which can easily lead to overlap of the two adjacent protrusions 31 or excessive local stress causing damage to the first electrode 50 during production. When the spacing f is greater than 10mm, the span between two adjacent protrusions 31 is too large to effectively reduce the surface roughness, thus making it difficult to effectively improve the slippage problem of the double-sided coating area 40 of the first electrode 50. This application controls the spacing f between two adjacent protrusions 31 to satisfy 2mm≤f≤10mm, which can effectively reduce the breakage problem of the first electrode 50 and effectively improve the slippage problem of the double-sided coating area 40 of the first electrode 50.

[0128] In one possible implementation, the protrusion 31 is straight, and the direction of extension of the straight line is parallel to the width direction of the first electrode 50, or the angle between the straight line and the width direction of the first electrode 50 is an acute angle, such as 2°, 5°, 8° or 10°.

[0129] In a possible implementation, the protrusions 31 are curved, for example, in a wavy line shape, and the extension direction of the center line of the wavy line can be parallel to the width direction of the first pole piece 50, or the included angle between the width direction of the first pole piece 50 and the extension direction of the center line of the wavy line is an acute angle.

[0130] In a possible implementation, the protrusions 31 are linear, the width e of the protrusions 31 satisfies 3mm≤e≤6mm, and the spacing f between two adjacent protrusions 31 satisfies 3mm≤f≤7mm.

[0131] In a possible implementation, the width e of the protrusions 31 can be, for example, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 5.5mm, 6mm, 7mm or 8mm.

[0132] In a possible implementation, the spacing f between two adjacent protrusions 31 can be, for example, 2mm, 2.5mm, 3mm, 4mm, 5mm, 5.5mm, 6mm, 7mm, 8mm, 9mm or 10mm.

[0133] In a possible implementation, referring to FIGS. 1 and 2, Figure 9 and Figure 10 As shown in FIGS. 1 and 2, the first pole piece 50 further includes a single-side coating area 11 provided with the first active material layer 20 on one side, and a blank foil area 12 not provided with the first active material layer 20 on both sides, and the double-side coating area 40, the single-side coating area 11 and the blank foil area 12 are sequentially connected along the length direction of the first pole piece 50.

[0134] One end of the tab 80 can be welded in the tab groove 44, and the other end of the tab 80 extends to the outside of the battery cell, and the tab groove 44 is not provided with the first active material layer 20.

[0135] In the utility model, the first pole piece 50 can be a positive pole piece, wherein the first current collector 10 can be an aluminum foil, and the active substance in the first active material layer 20 can include lithium cobaltate, lithium iron phosphate, lithium manganate and the like.

[0136] In a possible implementation, the first pole piece 50 is a positive pole piece, and the second pole piece 60 is a negative pole piece. The separator 70 can prevent the positive pole piece and the negative pole piece from being in contact and short-circuited, and in addition, the separator 70 has the function of allowing electrolyte ions in the electrolyte to pass through.

[0137] In a possible implementation, the concave-convex structure and the projection of the tab at least partially overlap in the thickness direction of the battery cell; since the tab has a relatively large thickness and the concave-convex structure of the first flat section has a relatively strong deformation ability, when the two concave-convex structures 30 at least partially overlap with the projection of the tab 80 in the thickness direction of the battery cell, the thickness of the battery cell at the position of the tab 80 can be effectively reduced, the thickness consistency can be improved, and the energy density can be improved.

[0138] In a possible implementation, the separator 70 can include a base material and a coating layer, where the base material can be a polythene (PE) single-layer film, a polypropylene (PP) single-layer film, or a polypropylene-polythene-polypropylene three-layer composite film, and the coating layer can be at least one of porous silicon dioxide, aluminum oxide, titanium dioxide, and zirconium dioxide.

[0139] The battery cell provided in the utility model is a winding core, and the material of the current collector in the positive plate and the negative plate can be set according to actual needs, and is not further limited herein. The second plate 60 is a negative plate, and the second plate 60 includes a second current collector and a second active material layer arranged on the surface of the second current collector. The second current collector can be a copper foil. The active substance in the second active material layer in the negative plate can include graphite, hard carbon, silicon, silicon monoxide, or silicon carbon or silicon oxide and the like. The plurality of grooves arranged on the negative plate can effectively improve the wetting effect of the electrolyte on the negative plate. The plurality of grooves arranged on the negative plate can be realized by, for example, laser wire drawing, negative embossing, or laser punching. The type and proportion of the active substance in the active material layer in the positive plate and the negative plate can also be set according to actual needs, and are not further limited herein.

[0140] The utility model also provides a battery comprising the battery cell.

[0141] The battery provided in the utility model embodiment further comprises a shell, the battery cell is located in the shell, and electrolyte is injected into the shell, so that the battery cell is immersed in the electrolyte.

[0142] In the battery provided in the utility model embodiment, the number of battery cells can be one, two, three, or more, and is not specifically limited herein.

[0143] The battery provided in the utility model can be a soft package battery or an aluminum shell battery.

[0144] In order to verify the improvement in the present application, the problem that the positive and negative tabs are prone to sliding and cause poor coverage of the positive and negative separators, and even cause the tabs to be folded, can be effectively solved, the cycle life and use safety of the battery are improved, and the following experiments are used for verification. The following are specific embodiment test data:

[0145] Example One

[0146] Preparation of the positive electrode sheet: the first electrode sheet 50 is a positive electrode sheet, the positive active material layer slurry is coated on the surface of the first current collector 10 which is an aluminum foil current collector by using a coating machine to form the first active material layer 20, and then dried at a temperature of 120°C to obtain an initial positive electrode sheet. The initial positive electrode sheet is cut according to actual needs, and the concave-convex structure 30 is processed on the first flat section 41 of the cut positive electrode sheet to obtain the positive electrode sheet.

[0147] Preparation of the negative electrode sheet: the second electrode sheet 60 is a negative electrode sheet, the negative active material layer slurry is coated on the surface of the second current collector which is a copper foil by using a coating machine to form the second active material layer, and then dried at a temperature of 100°C to obtain an initial negative electrode sheet. The initial negative electrode sheet is cut according to actual needs to obtain the negative electrode sheet.

[0148] Assembly of the battery cell: the above-mentioned positive electrode sheet, negative electrode sheet and separator 70 are stacked together and then wound to form a roll core. After baking to remove moisture, electrolyte is injected, and the battery cell is obtained by using a hot-pressing formation process, standing and formation.

[0149] In this embodiment one, the protrusions 31 in the concave-convex structure 30 are linear, the spacing between the concave-convex structure 30 and the edge of the first active material layer 20 is T1, and the width of the first active material layer 20 is T2, wherein T1 = 8 mm; T2 = 80 mm.

[0150] The area S1 of the concave-convex structure 30 processed on the first flat section 41 of the positive electrode sheet accounts for 20% of the area S2 of the first flat section 41, the width e of the protrusion 31 is 1 mm, the spacing f between adjacent two protrusions 31 is 4 mm, the length L1 of the first flat section is 100 mm, and the height H1 of the protrusion of the concave-convex structure 30 from the first active material layer 20 is 2 μm.

[0151] Embodiment two

[0152] The difference between this embodiment two and embodiment one is that the area S1 of the concave-convex structure 30 processed on the first flat section 41 of the positive electrode sheet accounts for 40% of the area S2 of the first flat section 41, the width e of the protrusion 31 is 5 mm, the height H1 of the protrusion of the concave-convex structure 30 from the first active material layer 20 is 50 μm, and the remaining parameters of the battery cell are the same as those of embodiment one.

[0153] Embodiment three

[0154] The difference between this embodiment three and embodiment one is that the ratio of the area S1 of the concave-convex structure 30 machined on the first flat section 41 of the positive plate to the area S2 of the first flat section 41 is S1 / S2=60%, the width e of the convex 31 is 8mm, the height H1 of the convex of the concave-convex structure 30 from the first active material layer 20 is 80μm, and the rest of the parameters of the battery cell are the same as those of embodiment one.

[0155] Embodiment four

[0156] In this embodiment four, the convex 31 in the concave-convex structure 30 is in the shape of a rhombus, the distance between the concave-convex structure 30 and the edge of the first active material layer 20 is T1, and the width of the first active material layer 20 is T2, wherein T1=8mm; T2=80mm.

[0157] The ratio of the area S1 of the concave-convex structure 30 machined on the first flat section 41 of the positive plate to the area S2 of the first flat section 41 is S1 / S2=60%, the angle θ between the two adjacent sides in the rhombus is 60°, the side length a of the rhombus is 2.5mm, the distance b between the two adjacent convexes 31 is 1.2mm, the length L1 of the first flat section is 100mm, and the height H1 of the convex of the concave-convex structure 30 from the first active material layer 20 is 20μm.

[0158] Embodiment five

[0159] The difference between this embodiment five and embodiment four is that the ratio of the area S1 of the concave-convex structure 30 machined on the first flat section 41 of the positive plate to the area S2 of the first flat section 41 is S1 / S2=40%, the side length a of the rhombus is 8mm, and the distance b between the two adjacent convexes 31 is 3mm; the length L1 of the first flat section is 100mm, and the height H1 of the convex of the concave-convex structure 30 from the first active material layer 20 is 62μm. The rest of the parameters of the battery cell are the same as those of embodiment four.

[0160] Embodiment six

[0161] In this embodiment six, the convex 31 in the concave-convex structure 30 is in the shape of a circle, the distance between the concave-convex structure 30 and the edge of the first active material layer 20 is T1, and the width of the first active material layer 20 is T2, wherein T1=8mm; T2=80mm.

[0162] The ratio S1 / S2 of the area S1 of the concave-convex structure 30 machined on the first flat section 41 to the area S2 of the first flat section 41 is 40%, the diameter D of the circumscribed circle of the convex part 31 is 0.3 mm, the distance c between the centers of the circumscribed circles of two adjacent convex parts 31 in the plane where the first electrode sheet 50 is located is 1 mm, the length L1 of the first flat section is 100 mm, and the height H1 of the concave-convex structure 30 protruding from the first active material layer 20 is 30 μm. The remaining parameters of the battery cell are the same as in Example One.

[0163] Example Seven

[0164] The difference between this Example Seven and Example Six is that the ratio S1 / S2 of the area S1 of the concave-convex structure 30 machined on the first flat section 41 to the area S2 of the first flat section 41 is 60%, the diameter D of the circumscribed circle of the convex part 31 is 5 mm, the distance c between the centers of the circumscribed circles of two adjacent convex parts 31 in the plane where the first electrode sheet 50 is located is 6 mm, the length L1 of the first flat section is 100 mm, and the height H1 of the concave-convex structure 30 protruding from the first active material layer 20 is 60 μm. The remaining parameters of the battery cell are the same as in Example Six.

[0165] Comparative Example One

[0166] In Comparative Example One, the positive electrode sheet is a conventional positive electrode sheet, and the negative electrode sheet is a conventional negative electrode sheet. Batteries of the same specifications are prepared in the same manner.

[0167] The test method is as follows:

[0168] 1. Capacity retention rate

[0169] The batteries obtained in the above examples and comparative example are respectively charged at 1.2 C to 4.3 V, then charged at 0.7 C to 4.45 V, then charged at constant voltage to 0.05 C, then discharged at 0.5 C to 3 V, then discharged at 0.5 C to 3 V, and then the above steps are repeated 800 times at 25°C. The initial capacity at the first cycle and the capacity after cycling at the 800th cycle are measured.

[0170] The capacity retention rate = initial capacity / capacity after cycling x 100%.

[0171] 2. Lithium precipitation of the battery cell

[0172] After the capacity retention rate test, the batteries obtained in the above examples and comparative example are respectively fully charged, and then the batteries are disassembled in a dry room environment to observe the lithium precipitation of the positive electrode sheet.

[0173] 3. Liquid retention amount detection

[0174] The liquid retention amount is the amount of electrolyte finally retained in the battery, in order to ensure the consumption of electrolyte in the battery formation, a certain amount of electrolyte is usually injected, and the excess electrolyte is extracted after formation, and the measurement is carried out in a weighing manner, wherein the liquid retention amount is the weight difference between the electrolyte injected into the battery and the excess electrolyte extracted.

[0175] The experimental results are shown in the following table:

[0176] Table 1

[0177]

[0178] Table 2

[0179]

[0180] Table 3

[0181]

[0182] By comparing the test results, it can be known that by arranging the concave-convex structure 30 on the first pole piece 50, and arranging at least part of the concave-convex structure 30 on the first flat section 41, the problem that the pole piece is prone to sliding to cause poor coverage of the positive and negative separators, and even cause the pole piece to be folded and lithium precipitation can be effectively solved; at the same time, the liquid retention amount of the innermost layer of the battery cell can be effectively improved, the problem of lithium precipitation at the edge of the negative pole piece caused by insufficient wetting of the innermost layer of the battery cell due to insufficient amount of electrolyte in the innermost layer of the battery cell can be improved, and the cycle performance and safety of the battery cell can be improved.

[0183] It should be noted that the numerical values and numerical ranges involved in the present application are approximate values, and there may be a certain range of errors due to the manufacturing process, which can be considered negligible by those skilled in the art.

[0184] In the description of the present application, it should be understood that the terms "center", "length", "width", "thickness", "top end", "bottom end", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", "axial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated position or element must have a particular orientation, a particular structure and operation, and therefore cannot be understood as a limitation on the present application.

[0185] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and do not connote or imply any relative importance or an ordering between the indicated technical features. Thus, a feature defined with "first", "second", etc. can include one or more of the features implicitly or explicitly. In the description of the present application, "a plurality of" means at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0186] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected to the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0187] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0188] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electric cell, characterized by, The first pole piece (50), the second pole piece (60) and the separator (70) are arranged in a laminated winding manner, and the separator (70) is arranged between the first pole piece (50) and the second pole piece (60) in a spaced manner; The first pole piece (50) comprises a first current collector (10) and a first active material layer (20) arranged on the first current collector (10), and a tab slot (44) is formed in the first active material layer (20), and the first current collector (10) is exposed from the tab slot (44), and a tab (80) is connected in the tab slot (44); The first pole piece (50) comprises a first flat section (41) located at the innermost circle of the battery cell, and the first pole piece (50) is provided with a concave-convex structure (30), the concave-convex structure (30) comprises a plurality of protrusions (31) arranged in a spaced manner and a plurality of concaves (311) arranged opposite to the protrusions (31), and at least part of the protrusions (31) and the concaves (311) are located at the first flat section (41). The second pole piece (60) comprises a second current collector and a second active material layer arranged on the second current collector, and the second active material layer is provided with a plurality of grooves, and the surface where the concaves (311) of the first pole piece (50) are located and the surface where the grooves are located are arranged opposite to each other. The area S1 of the concave-convex structure (30) accounts for 20% to 60% of the area S2 of the first flat section (41).

2. The electric cell of claim 1, wherein, The first pole piece (50) comprises a double-sided coating area (40) where the first active material layer (20) is arranged on both sides of the first current collector (10), and the first flat section (41) is located at the double-sided coating area (40), and the protrusions (31) protrude from the surface of the double-sided coating area (40).

3. The electric cell of claim 1, wherein, The openings of at least part of the concaves (311) are directed to the center position of the battery cell.

4. The electric cell of claim 2, wherein, The height H1 of the concave-convex structure (30) protruding from the first active material layer (20), the thickness H2 of the first active material layer (20) located at the double-sided coating area (40), and the thickness H3 of the first current collector (10) satisfy the following relationship: 0.1×H2-0.8×H3≤H1≤0.8×H2-0.8×H3.

5. The electric cell of claim 2, wherein, Along the length direction of the first pole piece (50): The length L1 of the first flat section (41) satisfies the following relationship: 4mm≤L1≤100mm; and / or, The first flat section (41) has a first edge (411), and the distance L2 between the concave-convex structure (30) and the first edge (411) satisfies the following relationship: 1mm≤L2≤5mm.

6. The cell of any of claims 1-5, wherein, Along the width direction of the first pole piece (50): The distance between the concave-convex structure (30) and the edge of the first active material layer (20) is T1, and the width of the first active material layer (20) is T2, and the following relationship is satisfied: 5%T2≤T1≤45%T2.

7. The electric cell of claim 5, wherein, The double-sided coating area (40) further comprises a first bending section (42) and a second straight section (43), the first straight section (41), the first bending section (42) and the second straight section (43) are sequentially connected along the length direction of the first pole piece (50); An end of the concave-convex structure (30) away from the first side (411) is a cut-off end (32), and the cut-off end (32) is located in the first straight section (41) or the first bending section (42) or the second straight section (43).

8. The electric cell of claim 1, wherein, The protrusions (31) are in a rhombus shape; and / or, An included angle θ between two adjacent sides of the rhombus satisfies 20° < θ < 90°; and / or, A side length a of the rhombus satisfies 2mm ≤ a ≤ 8mm; and / or, A distance b between two adjacent protrusions (31) satisfies 0.5mm ≤ b ≤ 3mm.

9. The electric cell of claim 1, wherein, The protrusions (31) are in a circular shape, an inscribed circle diameter D of the protrusions (31) satisfies 0.3mm ≤ D ≤ 8mm, and / or, projections of two adjacent protrusions (31) in a plane where the first pole piece (50) is located do not coincide.

10. The electric cell of claim 9, wherein, A distance c between centers of inscribed circles of two adjacent protrusions (31) in a plane where the first pole piece (50) is located satisfies 1mm ≤ c ≤ 6mm.

11. The electric cell of claim 1, wherein, The protrusions (31) are in a linear shape; A width e of the protrusions (31) satisfies 1mm ≤ e ≤ 8mm; and / or, A distance f between two adjacent protrusions (31) satisfies 2mm ≤ f ≤ 10mm.

12. The electric cell of claim 2, wherein, A height H1 of the concave-convex structure (30) protruding from the first active material layer (20) satisfies 2μm ≤ H1 ≤ 80μm.

13. The electric cell of claim 2, wherein, The first pole piece (50) further comprises a single-sided coating area (11) provided with the first active material layer (20) on one side, and a blank foil area (12) not provided with the first active material layer (20) on both sides, along the length direction of the first pole piece (50), the double-sided coating area (40), the single-sided coating area (11) and the blank foil area (12) are sequentially connected.

14. The electrically charged cell of claim 1, wherein, In a thickness direction of the battery cell, a projection of the concave-convex structure (30) and the tab (80) at least partially overlaps.

15. A battery, characterized by The battery cell comprises any one of claims 1-14. The battery cell comprises any one of claims 1-14.

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