Battery cell and battery

Abstract

The invention provides a battery cell and a battery, and the battery cell comprises a positive plate which comprises a positive current collector and positive active material layers respectively arranged on two opposite sides of the positive current collector; the negative plate is located on at least one side of the positive plate, the polarity of the positive plate is opposite to that of the negative plate, and the negative plate comprises a negative current collector and negative active material layers arranged on the two opposite sides of the negative current collector; the diaphragms are positioned between the adjacent positive plates and negative plates; the positive plate comprises a plurality of first bumps formed on the positive active material layer and a plurality of first grooves arranged opposite to the first bumps, and the negative plate comprises a plurality of second bumps formed on the negative active material layer and a plurality of second grooves arranged opposite to the second bumps; the first protruding block and the second groove are oppositely arranged, and the second protruding block and the first groove are oppositely arranged. According to the invention, the electrolyte distribution is improved, the electrolyte infiltration effect is improved, and the cycle life of the battery cell is further prolonged.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to battery cells and batteries. Background Art

[0002] With the advent of the 5G era and the rapid development of lithium-ion battery technology, people have put forward higher requirements on the energy density, fast charging capability and charge and discharge rate of lithium-ion batteries.

[0003] At present, the volume expansion of silicon-based materials in batteries is particularly serious. The volume expansion will cause cracks in the silicon-based negative electrode materials until they become powdered, unstable solid electrolyte interface (SEI) films, electrical contact failure, and will destroy the contact between the electrode material and the current collector, causing the active material to detach from the electrode sheet, resulting in rapid decay of the battery capacity.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art.

[0005] Application Contents

[0006] The embodiments of the present application provide a battery cell and a battery, which solve the problem of improving the distribution of electrolyte, enhancing the electrolyte infiltration effect, and thus increasing the cycle life of the battery cell.

[0007] The present application provides a battery cell, comprising:

[0008] A positive electrode sheet, comprising a positive electrode current collector and positive electrode active material layers respectively arranged on opposite sides of the positive electrode current collector;

[0009] A negative electrode sheet, located on at least one side of the positive electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer disposed on two opposite sides of the negative electrode current collector;

[0010] A separator, which is located between adjacent positive and negative electrode sheets;

[0011] The positive electrode sheet includes a plurality of first bumps formed on the positive electrode active material layer and a plurality of first grooves arranged opposite to the first bumps, and the negative electrode sheet includes a plurality of second bumps formed on the negative electrode active material layer and a plurality of second grooves arranged opposite to the second bumps;

[0012] The first protrusion is arranged opposite to the second groove, and the second protrusion is arranged opposite to the first groove.

[0013] Through the above-mentioned arrangement, that is, by forming bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet respectively, firstly, the first bump on the positive electrode sheet and the second bump on the negative electrode sheet can effectively support the diaphragm, ensuring that there is sufficient liquid storage space between the positive electrode sheet and the diaphragm, and between the negative electrode sheet and the diaphragm, thereby improving the electrolyte infiltration effect, improving the electrolyte distribution, increasing the liquid storage capacity of the area, and ensuring a good infiltration effect, thereby reducing the problem of insufficient electrolyte and poor infiltration caused by the squeezing of the positive and negative electrode layers inside the winding core due to repeated expansion and contraction of the negative electrode sheet, thereby improving the problems of deterioration of the electrode interface, poor negative electrode cycle stability and reduced battery capacity retention rate, reducing the attenuation rate of the battery capacity and improving the cycle life of the battery cell.

[0014] In addition, it should be noted that the protrusions (first protrusion, second protrusion) are provided on the positive electrode sheet and the negative electrode sheet to improve the deformation capacity of the positive electrode sheet and the negative electrode sheet. When the positive electrode sheet contacts the expanded negative electrode sheet, the protrusion on the positive electrode sheet can effectively absorb the expansion stress of the negative electrode sheet, which can buffer the expansion of the negative electrode sheet during the battery cycle and avoid the negative electrode sheet from cracking due to excessive expansion stress. At the same time, the second groove corresponding to the negative electrode sheet can be used to accommodate the first protrusion corresponding to the positive electrode sheet to prevent the first protrusion from deforming after being compressed; furthermore, the first protrusion provided on the positive electrode sheet can absorb part of the expansion stress of the negative electrode sheet, so that the negative electrode sheet does not completely rely on the resistance of its own material when expanding, delaying the fatigue of the negative electrode material, thereby improving the service life of the negative electrode sheet. Furthermore, by forming bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet, and the first bump is arranged opposite to the second groove, and the second bump is arranged opposite to the first groove, sufficient spacing is formed between the two side surfaces of the negative electrode sheet and the positive electrode sheet, preventing the spacing between one side surface of the negative electrode sheet and the positive electrode sheet from being too large, ensuring that the spacing between the two side surfaces of the negative electrode sheet and the positive electrode sheet is close, and providing corresponding space, which is beneficial to alleviating the expansion of the negative electrode sheet in different directions during the cycle.

[0015] In some optional embodiments, a first protrusion is provided on one side of the positive electrode active material layer away from the positive electrode current collector, and a first groove is provided on the other side of the positive electrode active material layer away from the positive electrode current collector;

[0016] A second groove is formed on at least one side of the negative electrode active material layer away from the negative electrode current collector, and a second protrusion is formed on the other side of the negative electrode active material layer away from the negative electrode current collector.

[0017] It should be noted that the second groove and the first bump structure can increase the storage and distribution space of the electrolyte, improve the infiltration effect of the electrolyte, and ensure that the battery has good electrochemical performance throughout its life cycle; during the charge and discharge cycle, the electrode material may expand in volume. The second groove and the first bump structure provide additional deformation space, which can effectively alleviate the volume expansion of the material.

[0018] In some optional embodiments, the height H1 of the first bump is greater than the height H2 of the second bump, and satisfies: 0.4H1≤H2≤0.95H1; and / or,

[0019] The depth H3 of the first groove is greater than the depth H4 of the second groove, and satisfies: 0.4H3≤H4≤0.95H3.

[0020] It should be noted that the thickness of the copper foil of the negative electrode collector in the negative electrode sheet of the battery cell is generally less than the thickness of the aluminum foil of the positive electrode collector in the positive electrode sheet. At the same embossing depth of the positive and negative electrode sheets, the aluminum foil of the positive electrode sheet is relatively difficult to break. If the embossing depth of the negative electrode sheet is too small, the improvement effect of the cycle volume expansion is not obvious; if the embossing depth of the negative electrode sheet is too large, the negative electrode active material layer is easy to fall off, and powder is easy to fall off during the winding process, causing short circuits and poor K values, affecting the process yield.

[0021] In some optional embodiments, the cross section of any one of the first protrusion, the first groove, the second protrusion and the second groove is circular; and / or

[0022] The first bump diameter D1 is greater than the second bump diameter D2 and satisfies: D2<0.95D1; and / or

[0023] The first groove diameter D3 is greater than the second groove diameter D4 and satisfies: D4<0.95D3.

[0024] It should be noted that for embossing rollers of the same specifications, the greater the embossing depth, the larger the diameters of the embossed bump area and the groove area. Since the embossing depth of the negative electrode sheet is smaller than that of the positive electrode sheet, it is necessary to satisfy that the diameter of the second bump of the negative electrode sheet is smaller than the diameter of the first bump of the positive electrode sheet, and the diameter of the second groove of the negative electrode sheet is smaller than the diameter of the first groove of the positive electrode sheet.

[0025] In some optional embodiments, the positive electrode sheet and the negative electrode sheet are stacked and wound to form a battery cell with at least two levels;

[0026] The battery cell comprises a plane area and an arc-shaped area, the first protrusion and the second groove in the plane area at least partially overlap in the thickness direction of the battery cell, and the ratio of the overlapping area to the plane area is less than 80%.

[0027] It should be noted that such a setting can ensure that there is enough space between the positive electrode sheet and the negative electrode sheet, which is conducive to alleviating the volume expansion of the negative electrode sheet. If the overlapping area of ​​the battery cell plane area is too high and greater than 80%, the space area between the positive electrode sheet and the negative electrode sheet will be smaller, the electrolyte will be difficult to store, the electrode sheet infiltration effect will be poor, and there will be insufficient space to alleviate the volume expansion.

[0028] In some optional embodiments, the first protrusion and the second groove located in the arc-shaped area at least partially overlap in the thickness direction of the battery cell, and the ratio of the overlapping area to the arc-shaped area is less than 50%.

[0029] It should be noted that such a setting can ensure that the arc has enough buffer space, and further avoid the occurrence of arc-area electrode breakage during the cycle of the battery cell. If the overlap area of ​​the arc area of ​​the battery cell is greater than 50%, the space between the positive electrode and the negative electrode in the arc area will be smaller, and the arc stress of the electrode cannot be released. There is a risk that the outer electrode will be subjected to greater force and breakage during the cycle.

[0030] In some optional embodiments, the plurality of first protrusions are arranged at intervals along the width direction and the length direction of the positive electrode active material layer, and the plurality of second grooves are arranged at intervals along the width direction and the length direction of the negative electrode active material layer;

[0031] The center distance L1 of two adjacent first bumps is smaller than the center distance L2 of two adjacent second bumps, and satisfies: 1.1≤L2 / L1≤3.

[0032] It should be noted that by reasonably designing the distance between the first bump and the second bump, especially by making L2 larger than L1, a larger liquid storage space can be provided inside the battery cell, which can provide a better expansion buffering effect during the charge and discharge cycle, reduce the volume change of the battery cell, improve the cycle stability, and help to increase the liquid retention and wettability of the electrolyte, thereby enhancing the electrochemical performance of the battery.

[0033] In some optional implementations, the center distance L1 between two adjacent first bumps and the center distance L2 between two adjacent second bumps satisfy: 1.5≤L2 / L1≤2.5.

[0034] It should be noted that a larger liquid storage space can be further provided inside the battery cell, which helps to improve the liquid retention and wettability of the electrolyte and ensure that the battery has good electrochemical properties during the charge and discharge process.

[0035] In some optional embodiments, the silicon content W in the negative electrode active material layer, the height H1 of the first bump and the silicon content W satisfy: 1200W≤H1≤3000W; and / or

[0036] The height H2 of the second bump and the silicon content W satisfy: 800W≤H2≤2500W.

[0037] It should be noted that the volume expansion of the negative electrode material Si is 300%. The greater the amount of silicon doped in the negative electrode of the battery cell, the greater the volume expansion during the battery cell cycle. The required spacing between the positive and negative electrodes is relatively large. When the embossing depth of the positive and negative electrodes is large enough, the huge volume expansion caused by the silicon negative electrode can be further alleviated. If the amount of silicon doped in the electrode is large and the embossing depth of the electrode is small, there will be no improvement in the cycle expansion of the battery cell. If the embossing depth is too large, cracks will be formed in the electrode paste area, causing the risk of short-circuiting and lithium precipitation in the battery cell.

[0038] In some optional embodiments, in the length direction of the positive electrode sheet, at least one level of the positive electrode sheet has a first avoidance area and a first non-avoidance area, the first bump is located in the first non-avoidance area, and the first avoidance area is not provided with the first bump.

[0039] It should be noted that by setting the first bump in the non-avoidance area, the contact of the electrode material and the infiltration effect of the electrolyte can be optimized, thereby improving the electrochemical reaction efficiency of the battery. The head of the positive electrode sheet of the battery cell is treated with an avoidance treatment, that is, the head of the positive electrode sheet is designed with an avoidance area, and the first bump structure is not designed in this area, which can improve the problems of unstable positive electrode sheet entry and serpentine electrode sheet, further improve the coverage and short circuit of the positive and negative electrode sheets, and further improve the process yield.

[0040] In some optional embodiments, the distance between the first air avoidance area and the first non-air avoidance area is greater than or equal to the width of the first layer of positive electrode sheets, and less than or equal to the sum of the widths of the first three layers of positive electrode sheets, wherein the first layer of positive electrode sheets is located in the center layer of the battery cell.

[0041] It should be noted that the curvature of the first two layers of the winding core is small, and the positive and negative electrodes are pressed tightly together. Embossing can easily cause powder to fall off, which can lead to a short circuit or an excessively large K value. It may cause cracks and pores at the first bump. In addition, the positive electrode and the diaphragm are in contact and friction, which can easily cause the bumps to fall off during the preparation process, and fall onto the diaphragm, blocking the holes and causing a short circuit. If the size of the air-avoidance area at the head of the positive electrode is large, the effect of improving cyclic expansion is poor.

[0042] In some optional embodiments, the positive electrode sheet further includes a positive electrode ear and a first protective tape, and the distance between the edge of the first protrusion and the area where the positive electrode ear is arranged is greater than or equal to 1 mm and less than or equal to 30 mm; and / or,

[0043] The distance between the edge of the first protrusion and the first protective tape is greater than or equal to 1 mm and less than or equal to 30 mm; and / or,

[0044] The negative electrode sheet further includes a negative electrode ear and a second protective tape, and the distance between the edge of the second groove and the area where the negative electrode ear is arranged is greater than or equal to 1 mm and less than or equal to 30 mm; and / or,

[0045] The distance between the edge of the second groove and the second protective tape is greater than or equal to 1 mm and less than or equal to 30 mm.

[0046] It should be noted that the first convex area of ​​the positive electrode sheet maintains a certain distance from the positive electrode ear, and the second groove area of ​​the negative electrode sheet maintains a certain distance from the negative electrode ear, which can prevent the positive and negative electrode ears from being compressed and affecting the welding tension of the ears, resulting in problems such as cold welding, unqualified welding tension, and ear folding. This is further conducive to improving the efficiency of the machine process.

[0047] In some optional embodiments, along the width direction of the positive electrode sheet, the distance between the first protrusion facing the upper edge of the positive electrode sheet and the upper edge of the positive electrode sheet is greater than or equal to 1 mm and less than or equal to 20 mm; and / or,

[0048] The distance between the first protrusion facing the lower edge of the positive electrode sheet and the lower edge of the positive electrode sheet is greater than or equal to 1 mm and less than or equal to 20 mm; and / or,

[0049] Along the width direction of the negative electrode sheet, the distance between the second groove facing the upper edge of the negative electrode sheet and the upper edge of the negative electrode sheet is greater than or equal to 1 mm and less than or equal to 20 mm; and / or,

[0050] The distance between the second groove facing the lower edge of the negative electrode sheet and the lower edge of the negative electrode sheet is greater than or equal to 1 mm and less than or equal to 20 mm.

[0051] It should be noted that it can avoid the positive and negative tabs being compressed and affecting the welding tension of the tabs, resulting in problems such as cold welding, unqualified welding tension and tab folding; it can avoid problems such as folding of the first and second protective tapes and bubbles caused by insufficient adhesion, which further affects the performance of the battery cell.

[0052] In some optional embodiments, along the width direction of the positive electrode sheet, the distance between the first protrusion facing the upper edge of the positive electrode sheet and the upper edge of the positive electrode sheet is greater than or equal to 3 mm and less than or equal to 10 mm; and / or,

[0053] The distance between the first protrusion facing the lower edge of the positive electrode sheet and the lower edge of the positive electrode sheet is greater than or equal to 3 mm and less than or equal to 10 mm; and / or,

[0054] Along the width direction of the negative electrode sheet, the distance between the second groove facing the upper edge of the negative electrode sheet and the upper edge of the negative electrode sheet is greater than or equal to 3 mm and less than or equal to 15 mm; and / or,

[0055] The distance between the second groove facing the lower edge of the negative electrode sheet and the lower edge of the negative electrode sheet is greater than or equal to 3 mm and less than or equal to 15 mm.

[0056] It should be noted that such a setting is conducive to the coverage of the positive and negative electrodes of the battery cell and improves the adhesion of the battery cell interface. If there is no gap in the width direction of the positive and negative electrodes, the interface adhesion will be relatively poor and the coverage failure rate will be relatively high. If the gap is too large, the embossed area will be relatively small, and the effect of embossing on improving cyclic expansion will be reduced.

[0057] In some optional embodiments, the tensile strength of the positive electrode current collector is greater than or equal to 280 MPa; and / or,

[0058] The ratio of the height of the first bump to the tensile strength of the positive electrode current collector is greater than or equal to 0.2 and less than or equal to 0.6; and / or,

[0059] The tensile strength of the negative electrode current collector is greater than or equal to 400 MPa; and / or,

[0060] The ratio of the height of the second protrusion to the tensile strength of the negative electrode current collector is greater than or equal to 0.1 and less than or equal to 0.4.

[0061] It should be noted that the positive electrode collector of the embossed positive electrode sheet is limited to a high-ductility aluminum foil, and the negative electrode collector of the embossed negative electrode sheet is limited to a high-strength copper foil. When the embossed electrode sheet is deformed, the current collector is not easy to break, thereby avoiding lithium precipitation of the battery cell. And during the cycle, it helps to relieve the huge stress caused by the volume expansion of the battery cell, thereby improving the volume expansion of the battery cell. The greater the embossing depth, that is, the height of the first bump, the greater the required tensile strength of the current collector, which must meet the deformation caused by the first bump, and the current collector must not break. If the height of the first bump and the tensile strength of the current collector do not satisfy the above formula, the embossing depth and the tensile strength of the current collector do not match, which will cause the paste to break or the current collector to break, causing a short circuit or lithium precipitation.

[0062] In some optional embodiments, the negative electrode active material layer includes a silicon-carbon composite material and a silicon-oxygen composite material, wherein the percentage content W1 of silicon element in the negative electrode active material layer is 3%≤W1≤50%.

[0063] In some optional embodiments, the silicon-carbon composite material includes a porous carbon matrix, silicon grains located in the pores of the porous carbon matrix, and a carbon layer located on the surface of the porous carbon matrix.

[0064] In some optional embodiments, the carbon layer includes openings arranged corresponding to the pores of the porous carbon matrix.

[0065] In some optional embodiments, the specific surface area of ​​the silicon-carbon composite material is 0.5 m 2 / g-10m 2 / g; and / or,

[0066] The particle size Dv50 of the silicon-carbon composite material is 6 μm-15 μm; and / or,

[0067] The powder resistivity of the silicon-carbon composite material ranges from 0.1 Ω·cm to 1000 Ω·cm; and / or,

[0068] The silicon content in the silicon-carbon composite material is 30%-75%.

[0069] It should be noted that the negative electrode sheet is a silicon-based negative electrode. The expansion of silicon-based negative electrode materials is relatively large. By setting a first bump design on the positive electrode sheet, the wettability of the electrolyte and the liquid storage space can be improved. What is important is that the first bump allows the positive electrode sheet to have deformation space, which can release the expansion of the silicon-based negative electrode, thereby improving the cycle performance.

[0070] The present application also provides a battery, comprising the battery cell as described above.

[0071] The present application also provides a battery cell and a battery, wherein the battery cell includes a positive electrode sheet, including a positive electrode current collector and a positive electrode active material layer respectively arranged on two opposite sides of the positive electrode current collector; a negative electrode sheet, located on at least one side of the positive electrode sheet, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer arranged on two opposite sides of the negative electrode current collector; a diaphragm, the diaphragm is located between adjacent positive electrode sheets and negative electrode sheets; the positive electrode sheet includes a plurality of first protrusions formed on the positive electrode active material layer and a plurality of first grooves arranged opposite to the first protrusions, the negative electrode sheet includes a plurality of second protrusions formed on the negative electrode active material layer and a plurality of second grooves arranged opposite to the second protrusions; the first protrusions are arranged opposite to the second grooves, and the second protrusions are arranged opposite to the first grooves.

[0072] By forming bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet respectively, firstly, the first bump on the positive electrode sheet and the second bump on the negative electrode sheet can effectively support the diaphragm, ensuring that there is sufficient liquid storage space between the positive electrode sheet and the diaphragm, and between the negative electrode sheet and the diaphragm, thereby improving the electrolyte infiltration effect, improving the electrolyte distribution, increasing the liquid storage capacity of the area, and ensuring a good infiltration effect, thereby reducing the problem of insufficient electrolyte and poor infiltration caused by squeezing the positive and negative electrode sheets between the layers inside the winding core due to repeated expansion and contraction of the negative electrode sheet, thereby improving the problems of deterioration of the electrode interface, poor negative electrode cycle stability and reduced battery capacity retention rate, reducing the attenuation rate of the battery capacity and improving the cycle life of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0074] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0075] Figure 2 A schematic diagram of the structure of a positive electrode sheet in a battery cell provided in an embodiment of the present application from a first perspective;

[0076] Figure 3 A schematic diagram of the structure of a negative electrode sheet in a battery cell provided in an embodiment of the present application from a first perspective;

[0077] Figure 4 A schematic diagram of the structure of the positive electrode active material layer in the battery cell provided in an embodiment of the present application;

[0078] Figure 5 A schematic diagram of the structure of the negative electrode active material layer in the battery cell provided in an embodiment of the present application;

[0079] Figure 6 A schematic diagram of the structure of the positive electrode sheet in the battery cell provided in an embodiment of the present application from a second perspective;

[0080] Figure 7 This is a schematic diagram of the structure of the negative electrode sheet in the battery cell provided in an embodiment of the present application from a second perspective.

[0081] Description of reference numerals:

[0082] 100-battery cell;

[0083] 110- positive electrode;

[0084] 111- positive electrode current collector;

[0085] 112- positive electrode active material layer;

[0086] 1121-first bump;

[0087] 1122-first groove;

[0088] 113- positive electrode ear;

[0089] 114-first protective tape;

[0090] 115-First air refuge area;

[0091] 116-First non-avoidance zone;

[0092] 120-negative electrode;

[0093] 121- negative electrode current collector;

[0094] 122- negative electrode active material layer;

[0095] 1221-second groove;

[0096] 1222-second bump;

[0097] 123-negative electrode ear;

[0098] 124- second protective tape;

[0099] 130-Diaphragm. DETAILED DESCRIPTION

[0100] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application. All other embodiments obtained are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0101] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0102] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication of the inner cavities of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0103] It should be noted that in the description of this application, the terms "first", "second", and "third" are only used to facilitate the description of different chambers, and cannot be understood as indicating or implying a sequential relationship, relative importance, or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include at least one of the features.

[0104] At present, the volume expansion of silicon-based materials in batteries is particularly serious. Volume expansion can cause cracks in silicon-based negative electrode materials until they become powdered, unstable solid electrolyte interface (SEI) membranes, electrical contact failure, and damage the contact between electrode materials and current collectors, causing active materials to separate from the pole pieces, causing rapid battery capacity decay. Moreover, expansion can generate great stress inside the battery, and may also reduce the porosity inside the battery, reduce the lithium ion movement channels, cause lithium metal precipitation, and affect battery safety.

[0105] In order to overcome the defects in the prior art, the battery cell and battery provided by the present application form bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet respectively. First, the first bump on the positive electrode sheet and the second bump on the negative electrode sheet can effectively support the diaphragm to ensure that there is sufficient liquid storage space between the positive electrode sheet and the diaphragm, and between the negative electrode sheet and the diaphragm, thereby improving the electrolyte infiltration effect, improving the electrolyte distribution, increasing the liquid storage capacity of the area, and ensuring a good infiltration effect, thereby reducing the problem of insufficient electrolyte and poor infiltration caused by squeezing the positive and negative electrode sheets between the layers inside the winding core due to repeated expansion and contraction of the negative electrode sheet, thereby improving the problems of deterioration of the electrode interface, poor negative electrode cycle stability and reduced battery capacity retention rate, reducing the attenuation rate of the battery capacity, and increasing the cycle life of the battery cell, thereby improving the cycle performance and safety performance of the battery, so as to solve the problem of lithium precipitation caused by poor cell infiltration and insufficient electrolyte during the cycle.

[0106] The contents of the present application will be described in detail below in conjunction with the accompanying drawings so that those skilled in the art can understand the contents of the present application more clearly and in detail.

[0107] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application, Figure 2 This is a schematic diagram of the first perspective structure of the positive electrode sheet in the battery cell provided in the embodiment of the present application. Figure 3 This is a schematic diagram of the first-perspective structure of the negative electrode sheet in the battery cell provided in an embodiment of the present application.

[0108] like Figures 1 to 3 As shown, the embodiment of the present application provides a battery cell 100, including:

[0109] The positive electrode sheet 110 includes a positive electrode current collector 111 and positive electrode active material layers 112 disposed on opposite sides of the positive electrode current collector 111;

[0110] A negative electrode sheet 120 is located on at least one side of the positive electrode sheet 110 , and the negative electrode sheet 120 includes a negative electrode current collector 121 and negative electrode active material layers 122 disposed on opposite sides of the negative electrode current collector 121 ;

[0111] A separator 130 , the separator 130 is located between the adjacent positive electrode sheet 110 and the negative electrode sheet 120 ;

[0112] The positive electrode sheet 110 includes a plurality of first bumps 1121 formed on the positive electrode active material layer 112 and a plurality of first grooves 1122 disposed opposite to the first bumps 1121, and the negative electrode sheet 120 includes a plurality of second bumps 1222 formed on the negative electrode active material layer 122 and a plurality of second grooves 1221 disposed opposite to the second bumps 1222;

[0113] The first protrusion 1121 is disposed opposite to the second groove 1221 , and the second protrusion 1222 is disposed opposite to the first groove 1122 .

[0114] It should be noted that the positive electrode sheet 110 , the separator 130 and the negative electrode sheet 120 are stacked together in sequence and then wound from the starting end to the ending end to form a roll core structure of the lithium-ion battery.

[0115] The positive electrode sheet 110 is located at the outermost side of the winding core structure. Of course, the positive electrode sheet 110, the separator 130 and the negative electrode sheet 120 are stacked in sequence to form a flat battery cell 100 structure. The specific electrodes can be referred to above.

[0116] It should be noted that, by adding an embossing roller containing a first bump 1121 to the winding process, the first bump 1121 and the second groove 1221 are manufactured on the surface of the pole piece; or the pole piece is processed to form a pole piece with a first bump 1121 in the film making process, and the battery cell 100 includes a positive pole piece 110, a negative pole piece 120, a separator 130, etc.

[0117] Among them, both the positive electrode sheet 110 and the negative electrode sheet 120 have grooves and convex areas, and there is a gap between the negative active material layer 122 of the negative electrode sheet 120 and the positive active material layer 112 of the positive electrode sheet 110, which can provide corresponding space to alleviate the expansion of the negative electrode sheet 120 in different directions during the cycle; if the first convex block 1121 area of ​​the positive electrode sheet 110 and the second groove 1221 area of ​​the negative electrode sheet 120 are set in a divergent manner, that is, the convex portion in the first convex block 1121 area extends away from the concave portion of the second groove 1221, if the area of ​​the negative electrode sheet 120 and the first groove 1122 area of ​​the positive electrode sheet 110 are set in a divergent manner, and the convex portion in the second convex block 1222 area extends away from the concave portion of the first groove 1122, it will cause the distance between the positive electrode sheet 110 and the negative electrode sheet 120 to be smaller on one side and larger on the other side, and the gap provided on both sides is too different, which is not conducive to the storage of point electrolyte, and is also not conducive to releasing the electrode stress and alleviating volume expansion.

[0118] Through the above-mentioned arrangement, that is, by forming bumps (first bump 1121, second bump 1222) and grooves (first groove 1122, second groove 1221) on the positive electrode sheet 110 and the negative electrode sheet 120 respectively, firstly, the first bump 1121 on the positive electrode sheet 110 and the second bump 1222 on the negative electrode sheet 120 can effectively support the diaphragm 130, and ensure that there is sufficient liquid storage space between the positive electrode sheet 110 and the diaphragm 130, and between the negative electrode sheet 120 and the diaphragm 130, thereby improving the electrolyte infiltration effect, improving the electrolyte distribution, increasing the liquid storage capacity of the area, and ensuring a good infiltration effect, thereby reducing the problem of insufficient electrolyte and poor infiltration caused by the squeezing of the positive electrode sheet 110 and the negative electrode sheet 120 between the layers inside the winding core due to repeated expansion and contraction of the negative electrode sheet 120, thereby improving the problems of deterioration of the electrode interface, poor negative electrode cycle stability and reduced battery capacity retention rate, reducing the attenuation rate of the battery capacity, and improving the cycle life of the battery cell.

[0119] In addition, it should be noted that the protrusions (first protrusion 1121, second protrusion 1222) are provided on the positive electrode sheet 110 and the negative electrode sheet 120 to improve the deformation capacity of the positive electrode sheet 110 and the negative electrode sheet 120. When the positive electrode sheet 110 contacts the expanded negative electrode sheet 120, the protrusion on the positive electrode sheet 110 can effectively absorb the expansion stress of the negative electrode sheet 120, which can buffer the expansion of the negative electrode sheet 120 during the battery cycle, and avoid the expansion stress of the negative electrode sheet 120 being too large and causing cracks. At the same time, the second groove 1221 corresponding to the negative electrode sheet 120 can be used to accommodate the first protrusion 1121 corresponding to the positive electrode sheet 110 to prevent the first protrusion 1121 from being deformed after being compressed; furthermore, the first protrusion 1121 provided on the positive electrode sheet 110 can absorb part of the expansion stress of the negative electrode sheet 120, so that the negative electrode sheet 120 does not completely rely on the resistance of its own material when expanding, delaying the fatigue of the negative electrode material, thereby improving the service life of the negative electrode sheet 120. Furthermore, by forming bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet, and the first bump is arranged opposite to the second groove, and the second bump is arranged opposite to the first groove, sufficient spacing is formed between the two side surfaces of the negative electrode sheet and the positive electrode sheet, preventing the spacing between one side surface of the negative electrode sheet and the positive electrode sheet from being too large, ensuring that the spacing between the two side surfaces of the negative electrode sheet and the positive electrode sheet is close, and providing corresponding space, which is beneficial to alleviating the expansion of the negative electrode sheet in different directions during the cycle.

[0120] It should be noted that the preparation of the positive electrode sheet 110: lithium cobalt oxide, a conductive agent (a mixture of conductive carbon black and carbon nanotubes), and PVDF are placed in NMP at a mass ratio of 97.60:1.35:1.05, and stirred evenly to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on the front and back sides of the aluminum foil, and the coating surface density is 0.01704g / cm2; after drying and rolling (rolling compaction is 4.2), a positive electrode sheet with a double-sided thickness of 90μm is obtained; the cut positive electrode sheet is subjected to convex processing with a special roller containing convex portions, wherein the first convex block height H1 is between 50μm-160μm, the first convex block diameter D1 is between 500μm-5000μm, and the center distance L1 between two adjacent first convex blocks is between 1000μm-10000μm.

[0121] Preparation of the negative electrode sheet 120: silicon-containing artificial graphite, conductive carbon black, styrene-butadiene rubber, and sodium carboxymethyl cellulose are placed in deionized water at a mass ratio of 97.2:0.5:1.3:1, wherein the silicon content in the silicon-containing artificial graphite is 10%; the above slurry is stirred evenly to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode collector, and dried, rolled, and slit in sequence to obtain a negative electrode sheet.

[0122] Preparation of the battery: The separator of the present application adopts a 9μm thick substrate + ceramic + coated separator. The electrolyte includes lithium salt LiPF6 and a solvent, and the solvent includes ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC), wherein the molar ratio of the three is DEC:EC:EMC=1:1:1. The above-mentioned cut positive electrode sheets, separators, and negative electrode sheets are stacked in sequence and wound into a wound structure battery cell. The battery cell is packaged, injected, formed, and sealed twice to obtain a lithium-ion battery.

[0123] In some embodiments, the first bump 1121 region includes a plurality of first bumps 1121 , and correspondingly, the second groove 1221 region includes a plurality of second grooves 1221 .

[0124] Continue to refer Figures 1 to 3 In some optional embodiments, a first protrusion 1121 is provided on one side of the positive electrode active material layer 112 away from the positive electrode current collector 111, and a first groove 1122 is provided on the other side of the positive electrode active material layer 112 away from the positive electrode current collector 111;

[0125] A second groove 1221 is formed on one side of the negative active material layer 122 away from the negative current collector 121 , and a second protrusion 1222 is formed on the other side of the negative active material layer 122 away from the negative current collector 121 .

[0126] It should be noted that the second groove 1221 and the first bump 1121 structure can increase the storage and distribution space of the electrolyte, improve the infiltration effect of the electrolyte, and ensure that the battery has good electrochemical performance throughout its life cycle; during the charge and discharge cycle, the electrode material may expand in volume. The second groove 1221 and the first bump 1121 structure provide additional deformation space, which can effectively alleviate the volume expansion of the material.

[0127] In some embodiments, a second groove 1221 is opened on the positive active material layer 112 located on one side of the positive current collector 111, or a second groove 1221 is opened on the positive active material layer 112 located on both sides of the positive current collector 111, and accordingly, a first protrusion 1121 is opened on the negative active material layer 122 located on one side of the negative current collector 121, or a first protrusion 1121 is opened on the negative active material layer 122 located on both sides of the negative current collector 121.

[0128] It should be noted that the second groove 1221 and the first protrusion 1121 can form different structures along different directions, and both of them are convex structures or concave structures.

[0129] It should be noted that, taking the positive electrode sheet 110 as an example, a first protrusion 1121 is provided on one side of the positive active material layer 112 , and a first groove 1122 is provided on the other side. The first protrusion 1121 and the first groove 1122 are both arranged on two sides away from the positive current collector 111 .

[0130] Correspondingly, in order to match the structure of the positive electrode sheet 110 , the negative electrode sheet 120 is also provided with a second protrusion 1222 and a second groove 1221 , and the manner of providing the second protrusion 1222 and the second groove 1221 may refer to the above-mentioned positive electrode sheet 110 .

[0131] Continue to refer Figures 1 to 3 In some optional embodiments, the height H1 of the first bump 1121 is greater than the height H2 of the second bump 1222 and satisfies: 0.4H1≤H2≤0.95H1; and / or

[0132] The depth H3 of the first groove 1122 is greater than the depth H4 of the second groove 1221 , and satisfies: 0.4H3≤H4≤0.95H3.

[0133] It should be noted that the embossing proposed in the present application may correspond to a group of grooves and protrusions. When describing the embossing of the positive electrode sheet 110 , it represents describing the first protrusion 1121 and the first groove 1122 on the positive electrode sheet 110 . Correspondingly, the same applies to the negative electrode sheet 120 .

[0134] The height H1 of the first bump 1121 and the depth H3 of the first groove 1122 may be the same. The height H2 of the second bump 1222 and the depth H4 of the second groove 1221 may be the same.

[0135] It should be noted that the thickness of the copper foil of the negative electrode collector 121 in the negative electrode sheet 120 of the battery cell 100 is generally less than the thickness of the aluminum foil of the positive electrode collector 111 in the positive electrode sheet 110. At the same embossing depth of the positive electrode sheet 110 and the negative electrode sheet 120, the aluminum foil of the positive electrode sheet 110 is relatively difficult to break. If the embossing depth of the negative electrode sheet 120 is too small, the improvement effect of the cycle volume expansion is not obvious; if the embossing depth of the negative electrode sheet 120 is too large, the negative electrode active material layer 122 is easy to fall off, and powder is easy to fall off during the winding process, resulting in short circuit and poor K value, affecting the process yield.

[0136] Table 1: H1, H2 and battery performance of various embodiments and comparative examples

[0137]

[0138] It should be noted that, as can be seen from Table 1, when compared with Example 1-0, when the first bump height H1 is the same, if the second bump height H2 is too small, the improvement effect of the cyclic thickness expansion is not obvious. When the second bump height H2 is too large, powder will fall off in the paste coating area, which may cause a short circuit, and the K value is relatively large, which affects the process yield.

[0139] Continue to refer Figures 1 to 3 In some optional embodiments, any one of the cross-sections of the first protrusion 1121, the first groove 1122, the second protrusion 1222 and the second groove 1221 is circular or equivalent to a circular shape.

[0140] In some optional embodiments, the diameter D1 of the first bump 1121 is greater than the diameter D2 of the second bump 1222 and satisfies: D2<0.95D1;

[0141] In some optional embodiments, the diameter D3 of the first groove 1122 is greater than the diameter D4 of the second groove 1221 , and satisfies: D4<0.95D3.

[0142] It should be noted that for embossing rollers of the same specifications, the greater the embossing depth, the larger the diameters of the embossed first bump 1121 area and the second groove 1221 area. Since the embossing depth of the negative electrode sheet 120 is smaller than the embossing depth of the positive electrode sheet 110, it is necessary to satisfy that the diameter of the second bump 1222 of the negative electrode sheet 120 is smaller than the diameter of the first bump 1121 of the positive electrode sheet 110, and the diameter of the second groove 1221 of the negative electrode sheet 120 is smaller than the diameter of the first groove 1122 of the positive electrode sheet 110.

[0143] Table 2: D1, D2 and battery performance of various embodiments and comparative examples

[0144]

[0145] It should be noted that, as can be seen from Table 2, compared with Example 2-0, when the first bump diameter D1 is the same, the larger the second bump diameter D2 is, the larger the K value is, which makes the negative electrode active material layer 122 easy to fall off, and powder is easy to fall off during the winding process, causing short circuit and poor K value, affecting the process yield.

[0146] In some optional embodiments, the positive electrode sheet 110 and the negative electrode sheet 120 are stacked and wound to form a battery cell 100 with at least two levels;

[0147] The battery cell 100 includes a plane area and an arc area. The first protrusion 1121 and the second groove 1221 in the plane area at least partially overlap in the thickness direction of the battery cell 100 , and the ratio of the overlapping area to the plane area is less than 80%.

[0148] It should be noted that such a configuration can ensure that there is enough space between the positive electrode sheet 110 and the negative electrode sheet 120, which is beneficial to alleviate the volume expansion of the negative electrode sheet 120. If the overlapping area of ​​the planar area of ​​the battery cell 100 is too high and greater than 80%, the space area between the positive electrode sheet 110 and the negative electrode sheet 120 will be smaller, the electrolyte will be difficult to store, the electrode infiltration effect will be poor, and there will be insufficient space to alleviate the volume expansion.

[0149] In addition, since the overlapping area accounts for less than 80%, this means that a certain amount of deformation space is still reserved in the thickness direction of the battery cell 100. This space can alleviate the volume expansion of the electrode material during the charge and discharge cycle, allowing the electrolyte to flow and distribute more freely inside the battery cell 100, improving the electrolyte infiltration effect, and ensuring that the battery has good electrochemical performance throughout its life cycle.

[0150] In some optional embodiments, the first protrusion 1121 and the second groove 1221 located in the arc-shaped area at least partially overlap in the thickness direction of the battery cell 100 , and the ratio of the overlapping area to the arc-shaped area is less than 50%.

[0151] It should be noted that such a setting can ensure that the arc has enough buffer space, and further can avoid the occurrence of the outer electrode sheet of the arc area of ​​the battery cell 100 being broken during the cycle process. If the overlap area of ​​the arc area of ​​the battery cell 100 is greater than 50%, the space between the positive electrode sheet 110 and the negative electrode sheet 120 in the arc area will be small, and the arc stress of the electrode sheet cannot be released. There is a risk that the outer electrode sheet will be subjected to greater force and break during the cycle.

[0152] Table 3: Regional proportion and battery performance of various embodiments and comparative examples

[0153]

[0154] It should be noted that, as can be seen from Table 3, compared with Example 3-0, in the case where the ratio of the overlapping area of ​​the first protrusion and the second groove in the plane area to the plane area is the same, the larger the ratio of the overlapping area of ​​the first protrusion and the second groove in the arc area to the arc area, the smaller the space between the positive electrode sheet 110 and the negative electrode sheet 120 in the arc area will be, and the arc stress of the electrode sheet cannot be released, resulting in the risk of the outer electrode sheet being subjected to greater force and breaking during the cycle.

[0155] Compared with Example 3-0, in Comparative Example 3-2, the larger the ratio of the overlapping area of ​​the first protrusion and the second groove in the plane area to the plane area, the smaller the space area between the positive electrode sheet 110 and the negative electrode sheet 120 will be, the lower the electrolyte retention capacity will be, and it will be difficult to store the electrolyte, the electrode wetting effect will be poor, and there will be insufficient space to alleviate volume expansion.

[0156] Figure 4 This is a schematic diagram of the structure of the positive electrode active material layer in the battery cell provided in the embodiment of the present application. Figure 5 This is a schematic diagram of the structure of the negative electrode active material layer in the battery cell provided in an embodiment of the present application.

[0157] like Figures 1 to 5 As shown, in some optional embodiments, there are multiple first protrusions 1121 and multiple second grooves 1221, and the multiple first protrusions 1121 are arranged at intervals along the width direction and the length direction of the positive electrode active material layer 112, and the multiple second grooves 1221 are arranged at intervals along the width direction and the length direction of the negative electrode active material layer 122.

[0158] The center distance L1 between two adjacent first bumps 1121 is smaller than the center distance L2 between two adjacent second bumps 1222 , and satisfies: 1.1≤L2 / L1≤3.

[0159] It should be noted that by reasonably designing the spacing between the first bump 1121 and the second bump 1222, especially by making L2 greater than L1, a larger liquid storage space can be provided inside the battery cell 100, which can provide a better expansion buffering effect during the charge and discharge cycle, reduce the volume change of the battery cell 100, improve the cycle stability, and help to increase the liquid retention and wettability of the electrolyte, thereby enhancing the electrochemical performance of the battery.

[0160] In addition, by limiting the distance between two adjacent second grooves 1221 in the second groove 1221 area of ​​the negative electrode sheet 120 and the distance between two adjacent first bumps 1121 in the first bump 1121 area of ​​the positive electrode sheet 110, a suitable distance relationship can provide a larger liquid storage space, more effectively improve the liquid retention, wettability and buffering effect on the expansion of the silicon negative electrode. If the distance between the second grooves 1221 in the negative electrode sheet 120 is too small, the second grooves 1221 will be densely packed, and the negative electrode sheet 120 is prone to powder shedding and foil leakage.

[0161] If the spacing between the second grooves 1221 of the negative electrode sheet 120 is too large, the first bumps 1121 are too sparse, and the space between the positive electrode sheet 110 and the negative electrode sheet 120 of the battery cell 100 is insufficient, it is not conducive to the storage and infiltration of the electrolyte, and the effect of improving the cyclic expansion is not good.

[0162] In some optional implementations, the center distance L1 between two adjacent first bumps 1121 and the center distance L2 between two adjacent second bumps 1222 satisfy: 1.5≤L2 / L1≤2.5.

[0163] It should be noted that a larger liquid storage space can be further provided inside the battery cell 100, which helps to improve the liquid retention and wettability of the electrolyte and ensure that the battery has good electrochemical performance during the charge and discharge process.

[0164] In some embodiments, the ratio of L2 / L1 can be 1.5, 2, 2.5, or any value in between.

[0165] Table 4 is a comparison table of the ratio of L2 / L1 and the wetting effect of each embodiment and comparative example

[0166]

[0167] It should be noted that, as can be seen from Table 4, compared with Example 4-0, the ratio L2 / L1 of Comparative Example 4-1 is too small, L2 is smaller than L1, resulting in dense second grooves 1221, and the negative electrode sheet 120 is prone to powder loss and foil leakage. A smaller liquid storage space is provided inside the battery cell, the liquid retention capacity is low, the electrolyte infiltration effect is poor, the lithium precipitation is serious, and the cycle expansion is large.

[0168] Compared with Example 4-0, in Comparative Example 4-2, the L2 / L1 ratio is too large, the first bumps 1121 are too sparse, and the space between the positive electrode sheet 110 and the negative electrode sheet 120 is insufficient, which is not conducive to the storage and infiltration of the electrolyte, and the improvement effect of cyclic expansion is not good.

[0169] In some optional embodiments, the silicon content W in the negative electrode active material layer 122 and the height H1 of the first bump 1121 satisfy the following relationship: 1200W≤H1≤3000W.

[0170] The height H2 of the second bump 1222 and the silicon content W satisfy: 800W≤H2≤2500W.

[0171] It should be noted that the volume expansion of the negative electrode material Si is 300%. The greater the amount of silicon doped in the negative electrode of the battery cell 100, the greater the volume expansion of the battery cell 100 during the cycle. The required spacing between the positive electrode sheet 110 and the negative electrode sheet 120 is relatively large. When the embossing depth of the positive electrode sheet 110 and the negative electrode sheet 120 is large enough, the huge volume expansion caused by the silicon negative electrode can be further alleviated. If the amount of silicon doped in the electrode sheet is large and the embossing depth of the electrode sheet is small, there is no improvement in the cycle expansion of the battery cell 100. If the embossing depth is too large, cracks will be formed in the electrode paste coating area, resulting in the risk of short-circuiting lithium deposition in the battery cell 100.

[0172] Figure 6 A schematic diagram of the structure of the positive electrode sheet in the battery cell provided in the embodiment of the present application from a second perspective, as shown in FIG. Figure 6 As shown, in some optional embodiments, in the length direction of the positive electrode sheet 110 , at least one level of the positive electrode sheet 110 has a first clearance area 115 and a first non-clearance area 116 , and the first protrusion 1121 is located in the first non-clearance area 116 .

[0173] It should be noted that by providing the first bump 1121 in the non-avoidance area, the contact of the electrode material and the infiltration effect of the electrolyte can be optimized, thereby improving the electrochemical reaction efficiency of the battery. The head of the positive electrode sheet 110 of the battery cell 100 is treated with an avoidance treatment, that is, the head of the positive electrode sheet 110 is designed with an avoidance area, and the first bump 1121 structure is not designed in this area, which can improve the problems of unstable entry of the positive electrode sheet 110 and serpentine electrode sheet, further improve the coverage and short circuit between the positive electrode sheet 110 and the negative electrode sheet 120, and further improve the process yield.

[0174] like Figure 1 and Figure 6 As shown, in some optional embodiments, the distance between the first air avoidance area 115 and the first non-air avoidance area 116 is greater than or equal to the width of the first layer of positive electrode sheets 110, and less than or equal to the sum of the widths of the first three layers of positive electrode sheets 110, wherein the first layer of positive electrode sheets 110 is located in the center layer of the battery cell 100.

[0175] It should be noted that the curvature of the first two layers of the winding core is small, and the positive electrode sheet 110 and the negative electrode sheet 120 are pressed tightly together. The embossing is likely to cause powder to fall off, which may lead to a short circuit or an excessively large K value; cracks and pores may be caused at the first bump 1121; and the positive electrode sheet 110 and the diaphragm 130 are in contact and friction, which may easily cause the bulge to fall off during the preparation process, fall onto the diaphragm 130, block the hole, and cause a short circuit. If the size of the air avoidance area at the head of the positive electrode sheet 110 is large, the effect of improving the cyclic expansion is not good.

[0176] Figure 7A schematic diagram of the structure of the negative electrode sheet in the battery cell provided in the embodiment of the present application from a second perspective, as shown in FIG. Figure 6 and Figure 7 As shown, in some optional embodiments, the positive electrode sheet 110 further includes a positive electrode ear 113 and a first protective tape 114, and the distance between the edge of the first protrusion 1121 and the area where the positive electrode ear 113 is set is greater than or equal to 1 mm and less than or equal to 30 mm.

[0177] And / or, the distance between the edge of the first protrusion 1121 and the first protective tape 114 is greater than or equal to 1 mm and less than or equal to 30 mm.

[0178] And / or, the negative electrode sheet 120 further includes a negative electrode ear 123 and a second protective tape 124, and the distance between the edge of the second groove 1221 and the area where the negative electrode ear 123 is arranged is greater than or equal to 1 mm and less than or equal to 30 mm.

[0179] And / or, the distance between the edge of the second groove 1221 and the second protective tape 124 is greater than or equal to 1 mm and less than or equal to 30 mm.

[0180] It should be noted that the first protrusion 1121 area of ​​the positive electrode sheet 110 and the positive electrode ear 113 are kept at a certain distance, and the second groove 1221 area of ​​the negative electrode sheet 120 and the negative electrode ear 123 are kept at a certain distance, which can prevent the positive electrode ear 113 and the negative electrode ear 123 from being compressed and affecting the electrode ear welding tension, resulting in problems such as cold welding, unqualified welding tension and electrode ear folding. This is further conducive to improving the efficiency of the machine process.

[0181] In addition, it should be noted that the first protective tape 114 is all tapes that protect the positive electrode ears 113 on the positive electrode sheet 110 to prevent lithium deposition at the positive electrode ears 113 ; correspondingly, the second protective tape 124 is all tapes that protect the negative electrode ears 123 on the negative electrode sheet 120 .

[0182] In some embodiments, the finishing tape is the tape at the junction of the paste-coated area at the tail of the pole piece and the current collector, ensuring coverage to prevent lithium deposition at the tail of the battery cell 100.

[0183] It should be noted that the spacing between the first bump 1121 area and the first adhesive tape area must satisfy 1mm≤L5≤30mm. The first bump 1121 area and the first adhesive tape area satisfying the above conditions can avoid problems such as adhesive tape folding and bubbles caused by insufficient adhesion of the first protective adhesive tape 114, thereby further affecting the performance of the battery cell 100. If L4 between the first bump 1121 area and the positive electrode ear 113 is greater than 30mm, the avoidance spacing is too large, the overall positive electrode sheet 110 embossed area is reduced, and the embossing improvement effect will be reduced.

[0184] Accordingly, the distance design between the second groove 1221 and the second protective tape 124 may be referred to above and will not be further limited herein.

[0185] Table 5: L4, L5 and battery performance of various embodiments and comparative examples

[0186]

[0187] It should be noted that, as can be seen from Table 5, compared with Example 5-0, in Comparative Examples 5-1 and 5-3, the distance L5 between the first bump and the first tape is too large, or the distance between the first bump and the positive electrode ear is too large, and the avoidance distance is too large. The embossing area of ​​the overall positive electrode sheet 110 is reduced, and the embossing improvement effect is reduced. The expansion buffering effect is low during the charge and discharge cycle, which is not conducive to the infiltration of the electrolyte.

[0188] Compared with Example 5-0, when L5 is too small, the battery K value is large, the interface adhesion is relatively poor, and the winding process yield is low, which affects the process yield.

[0189] In some optional embodiments, along the width direction of the positive electrode sheet 110 , the distance between the first protrusion 1121 facing the upper edge of the positive electrode sheet 110 and the upper edge of the positive electrode sheet 110 is greater than or equal to 1 mm and less than or equal to 20 mm.

[0190] And / or, the distance between the first protrusion 1121 facing the lower edge of the positive electrode sheet 110 and the lower edge of the positive electrode sheet 110 is greater than or equal to 1 mm and less than or equal to 20 mm.

[0191] And / or, along the width direction of the negative electrode sheet 120 , the distance between the second groove 1221 facing the upper edge of the negative electrode sheet 120 and the upper edge of the negative electrode sheet 120 is greater than or equal to 1 mm and less than or equal to 20 mm.

[0192] And / or, the distance between the second groove 1221 facing the lower edge of the negative electrode sheet 120 and the lower edge of the negative electrode sheet 120 is greater than or equal to 1 mm and less than or equal to 20 mm.

[0193] It should be noted that the positive tab 113 and the negative tab 123 can be prevented from being compressed and affecting the tab welding tension, resulting in problems such as cold welding, unqualified welding tension and tab folding; the first protective tape 114 and the second protective tape 124 can be prevented from having insufficient adhesion, resulting in folding of the tape, bubbles and other problems, thereby further affecting the performance of the battery cell 100.

[0194] In some optional embodiments, along the width direction of the positive electrode sheet 110 , the distance between the first protrusion 1121 facing the upper edge of the positive electrode sheet 110 and the upper edge of the positive electrode sheet 110 is greater than or equal to 3 mm and less than or equal to 10 mm.

[0195] And / or, the distance between the first protrusion 1121 facing the lower edge of the positive electrode sheet 110 and the lower edge of the positive electrode sheet 110 is greater than or equal to 3 mm and less than or equal to 10 mm.

[0196] And / or, along the width direction of the negative electrode sheet 120 , the distance between the second groove 1221 facing the upper edge of the negative electrode sheet 120 and the upper edge of the negative electrode sheet 120 is greater than or equal to 3 mm and less than or equal to 15 mm.

[0197] And / or, the distance between the second groove 1221 facing the lower edge of the negative electrode sheet 120 and the lower edge of the negative electrode sheet 120 is greater than or equal to 3 mm and less than or equal to 15 mm.

[0198] It should be noted that such a setting is conducive to the coverage of the positive electrode sheet 110 and the negative electrode sheet 120 of the battery cell 100 and improves the adhesion of the battery cell 100 interface. If there is no avoidance in the width direction of the positive electrode sheet 110 and the negative electrode sheet 120, the interface adhesion will be relatively poor and the coverage failure rate will be relatively high. If the avoidance distance is too large, the embossing area will be relatively small, and the effect of embossing on improving cyclic expansion will be reduced. Among them, in order to ensure the coverage of the positive electrode sheet 110 and the negative electrode sheet 120 in the width direction, the avoidance distance of the negative electrode sheet 120 in the width direction is as large as possible.

[0199] like Figure 6 and Figure 7 As shown, in some embodiments, the distance between the first protrusion 1121 facing the upper edge of the positive electrode sheet 110 and the upper edge of the positive electrode sheet 110 is L6, and the distance between the second groove 1221 facing the upper edge of the negative electrode sheet 120 and the upper edge of the negative electrode sheet 120 is L6; the distance between the first protrusion 1121 facing the lower edge of the positive electrode sheet 110 and the lower edge of the positive electrode sheet 110 is L7, and the distance between the second groove 1221 facing the lower edge of the negative electrode sheet 120 and the lower edge of the negative electrode sheet 120 is L7.

[0200] Table 6 is a comparison table of L6, L7 and battery performance of each embodiment and comparative example

[0201]

[0202] It should be noted that, as shown in Table 6, when L7 or L6 is too large for Comparative Examples 6-1 and 6-3 respectively compared with Example 6-0, the embossing area will be relatively small, and the effect of improving cyclic expansion will be poor.

[0203] Compared with Example 6-0, when L7 is too small, the interface adhesion is relatively poor and the coverage defect rate is relatively high, resulting in a low process yield.

[0204] In some optional embodiments, the tensile strength of the positive electrode current collector 111 is greater than or equal to 280 MPa.

[0205] And / or, a ratio of the height of the first bump 1121 to the tensile strength of the positive electrode current collector 111 is greater than or equal to 0.2 and less than or equal to 0.6.

[0206] And / or, the tensile strength of the negative electrode current collector 121 is greater than or equal to 400 MPa.

[0207] And / or, a ratio of the height of the second bump 1222 to the tensile strength of the negative electrode current collector 121 is greater than or equal to 0.1 and less than or equal to 0.4.

[0208] It should be noted that the positive electrode collector 111 of the embossed positive electrode sheet 110 is limited to a high-ductility aluminum foil, and the negative electrode collector 121 of the embossed negative electrode sheet 120 is limited to a high-strength copper foil. When the embossed electrode sheet is deformed, the current collector is not easy to break, thereby avoiding lithium precipitation of the battery cell 100. And during the cycle process, it helps to relieve the huge stress caused by the volume expansion of the battery cell 100, thereby improving the volume expansion of the battery cell 100. The greater the embossing depth, that is, the height of the first bump 1121, the greater the required tensile strength of the current collector, which must meet the deformation caused by the first bump 1121, and the current collector must not break. If the height of the first bump 1121 and the tensile strength of the current collector do not satisfy the above formula, the embossing depth and the tensile strength of the current collector do not match, which will cause the paste to break or the current collector to break, causing a short circuit or lithium precipitation.

[0209] The limitation between the height of the second bump 1222 and the tensile strength of the negative electrode current collector 121 may also be referred to the above.

[0210] Table 7 is a comparison table of the ratio of the first bump / second bump height to the tensile strength of the current collector and the battery lithium deposition of each embodiment and comparative example.

[0211]

[0212]

[0213] It should be noted that, as can be seen from Table 7, when the ratio of the first bump height to the tensile strength of the positive electrode collector and the ratio of the second bump height to the tensile strength of the negative electrode collector are too large for Comparative Examples 7-1 and 7-2 respectively compared with Example 7-0, the current collector is prone to rupture, and the paste-coated area may also rupture and lose powder, resulting in a larger K value of the battery and more serious lithium plating in the battery cell.

[0214] Compared with Example 7-0, in Comparative Example 7-3, the ratio of the first bump height to the tensile strength of the positive electrode collector and the ratio of the second bump height to the tensile strength of the negative electrode collector are too small, that is, the embossing bump height is small, and the effect of improving the cyclic expansion is not good.

[0215] In some embodiments, the negative electrode active material layer 122 may include a silicon-carbon composite material and a silicon-oxygen composite material, wherein the percentage content W1 of silicon element in the negative electrode active material layer 122 is 3%≤W1≤50%.

[0216] The silicon-carbon composite material may include a porous carbon matrix, silicon grains in the pores of the porous carbon matrix, and a carbon layer on the surface of the porous carbon matrix, wherein the material of the carbon layer may be shaped carbon or amorphous carbon.

[0217] In some embodiments, the carbon layer may include openings arranged corresponding to the pores of the porous carbon matrix.

[0218] In this way, by setting openings on the carbon layer corresponding to the pores of the porous carbon matrix, the wettability of the electrolyte to the negative electrode active material can be improved, while the expansion performance of silicon can be reduced, the cycle life of the battery cell can be improved, and the service life of the battery can be increased.

[0219] In some embodiments, the material of the negative electrode active material layer 122 may further include at least one of artificial graphite, natural graphite, mesophase carbon microbeads, graphene, soft carbon, hard carbon, soft carbon-coated graphite material, and hard carbon-coated graphite material.

[0220] In some embodiments, the specific surface area of ​​the silicon-carbon composite material is 0.5 m 2 / g-10m 2 / g, for example, the specific surface area of ​​the silicon-carbon composite material can be 0.5m 2 / g, 0.9m 2 / g, 1.3m 2 / g, 1.5m 2 / g, 1.85m 2 / g, 2.0m 2 / g, 2.3m 2 / g, 2.7m 2 / g, 3.2m 2 / g, 3.6m 2 / g, 3.8m 2 / g, 4.6m 2 / g, 4.8m 2 / g, 5.1m 2 / g, 5.4m 2 / g, 5.8m 2 / g, 6.1m 2 / g, 6.5m 2 / g, 6.8m 2 / g, 7.2m 2 / g, 7.5m 2 / g, 7.8m2 / g, 8.3m 2 / g, 8.9m 2 / g, 9.4m 2 / g and 9.9m 2 Alternatively, the specific surface area of ​​the silicon-carbon composite material may be greater than or equal to 0.5 m 2 / g and less than or equal to 10m 2 Any value within the range of / g.

[0221] In this way, by controlling the specific surface area in the silicon-carbon composite material, the solid electrolyte interface (SEI) film during the charging process can be reduced, and the cycle performance and service life can be improved. It can avoid the situation where the thickness of the SEI film is too small due to the small specific surface area, thereby failing to effectively isolate the electrolyte and the negative electrode active material layer 122. It can also avoid the SEI film being too large due to the large specific surface area, and can reduce the impact of the SEI film being too thick on the capacity and efficiency of the battery.

[0222] In some embodiments, the particle size Dv50 of the silicon-carbon composite material is 6 μm-15 μm, for example, it can be one of 6 μm, 7 μm, 8 μm, 9 μm, 11 μm, 13 μm and 14 μm, or it can be any point value within the range of 6 μm or more and 15 μm or less.

[0223] Thus, by controlling the particle size of the silicon-carbon composite material within the above range, it is possible to avoid the situation where the specific surface area of ​​the silicon particles is increased when the particle size is too small, thereby increasing the side reactions. It is also possible to avoid the problem where the silicon particles are easily expanded too much when the particle size is too large, thereby blocking the pores of the porous carbon matrix and affecting the infiltration of the electrolyte.

[0224] The average sphericity of the silicon-carbon material is in the range of 0.5-1, for example, the average sphericity can be one of 0.6, 0.7, 0.8 and 0.9. Compared with non-spherical particles, the higher the sphericity, the closer the shape is to a sphere, so that when its volume expands, the impact on the structure of the negative electrode sheet 120 is smaller, and the overall structural stability of the negative electrode sheet 120 can be maintained during expansion.

[0225] In addition, spherical particles can improve the mechanical strength and stability of the material and reduce the stress concentration between particles caused by expansion, thereby reducing the risk of mechanical wear and damage to the material during the cycle.

[0226] In some embodiments, the powder resistivity of the silicon-carbon composite material ranges from 0.1Ω·cm to 1000Ω·cm. For example, the powder resistivity of the silicon-carbon composite material may be one of 0.1Ω·cm, 0.9Ω·cm, 1.2Ω·cm, 1.3Ω·cm, 1.8Ω·cm, 2.7Ω·cm, 4.6Ω·cm, 7.8Ω·cm, 11Ω·cm, 25Ω·cm, 38Ω·cm, 60Ω·cm, 100Ω·cm, 200Ω·cm, 300Ω·cm, 400Ω·cm, 500Ω·cm, 600Ω·cm, 700Ω·cm, 800Ω·cm, 900Ω·cm and 1000Ω·cm. Alternatively, the powder resistivity of the silicon-carbon composite material may be any point value within the range of greater than or equal to 0.1Ω·cm and less than or equal to 1000Ω·cm.

[0227] In some embodiments, the silicon content in the silicon-carbon composite material may be 30%-75%, for example, the silicon content in the silicon-carbon composite material may be one of 30%, 35%, 41%, 45%, 49%, 51%, 55%, 59%, 61%, 64%, 71% and 84%. Alternatively, the silicon content in the silicon-carbon composite material may be any point value within the range of greater than or equal to 30% and less than or equal to 75%.

[0228] In this way, it is possible to avoid excessive expansion of the negative electrode sheet due to excessive silicon content in the negative electrode active material layer 122, thereby deforming the overall structure of the silicon-carbon particles, and to avoid a reduction in the energy density of the battery due to too low silicon content.

[0229] In some embodiments, the embodiments of the present application can be applied to STP, multi-electrode, and laminated structures, and the positive electrode material is limited to at least one of lithium cobalt oxide, ternary materials, lithium iron phosphate, lithium nickel manganese oxide, and lithium-rich manganese-based. In addition, the positive electrode embossing process is also applicable to improving sodium ion batteries, lithium sulfur batteries, etc.

[0230] The battery cell provided in the embodiment of the present application includes a positive electrode sheet, including a positive electrode collector and a positive electrode active material layer respectively arranged on two opposite sides of the positive electrode collector; a negative electrode sheet, located on at least one side of the positive electrode sheet, the negative electrode sheet includes a negative electrode collector and a negative electrode active material layer arranged on two opposite sides of the negative electrode collector; a diaphragm, the diaphragm is located between adjacent positive electrode sheets and negative electrode sheets; the positive electrode sheet includes a plurality of first protrusions formed on the positive electrode active material layer and a plurality of first grooves arranged opposite to the first protrusions, the negative electrode sheet includes a plurality of second protrusions formed on the negative electrode active material layer and a plurality of second grooves arranged opposite to the second protrusions; the first protrusions are arranged opposite to the second grooves, and the second protrusions are arranged opposite to the first grooves.

[0231] By forming bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet respectively, firstly, the first bump on the positive electrode sheet and the second bump on the negative electrode sheet can effectively support the diaphragm, ensuring that there is sufficient liquid storage space between the positive electrode sheet and the diaphragm, and between the negative electrode sheet and the diaphragm, thereby improving the electrolyte infiltration effect, improving the electrolyte distribution, increasing the liquid storage capacity of the area, and ensuring a good infiltration effect, thereby reducing the problem of insufficient electrolyte and poor infiltration caused by squeezing the positive and negative electrode sheets between the layers inside the winding core due to repeated expansion and contraction of the negative electrode sheet, thereby improving the problems of deterioration of the electrode interface, poor negative electrode cycle stability and reduced battery capacity retention rate, reducing the attenuation rate of the battery capacity and improving the cycle life of the battery cell.

[0232] In addition, an embodiment of the present application further provides a battery, including a battery cell 100 .

[0233] The specific structure, working principle and function of the battery cell 100 have been described in detail in the aforementioned embodiments and will not be repeated here.

[0234] The battery provided in the embodiment of the present application forms bumps (first bump, second bump) and grooves (first groove, second groove) on the positive electrode sheet and the negative electrode sheet respectively. Firstly, the first bump on the positive electrode sheet and the second bump on the negative electrode sheet can effectively support the diaphragm to ensure that there is sufficient liquid storage space between the positive electrode sheet and the diaphragm, and between the negative electrode sheet and the diaphragm, thereby improving the electrolyte infiltration effect, improving the electrolyte distribution, increasing the liquid storage capacity of the area, and ensuring a good infiltration effect, thereby reducing the problem of insufficient electrolyte and poor infiltration caused by squeezing the positive and negative electrode sheets between the layers inside the winding core due to repeated expansion and contraction of the negative electrode sheet, thereby improving the problems of deterioration of the electrode sheet interface, poor negative electrode cycle stability and reduced battery capacity retention rate, reducing the attenuation rate of the battery capacity and improving the cycle life of the battery cell.

[0235] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell (100), characterized in that: include: A positive electrode sheet (110) comprising a positive electrode current collector (111) and positive electrode active material layers (112) respectively arranged on two opposite sides of the positive electrode current collector (111); A negative electrode sheet (120), the negative electrode sheet (120) comprising a negative electrode current collector (121) and a negative electrode active material layer (122) disposed on two opposite sides of the negative electrode current collector (121); A separator (130), the separator (130) being located between the adjacent positive electrode sheet (110) and the adjacent negative electrode sheet (120); The positive electrode sheet (110) comprises a plurality of first convex blocks (1121) formed on the positive electrode active material layer (112) and a plurality of first concave blocks (1122) arranged opposite to the first convex blocks (1121); the negative electrode sheet (120) comprises a plurality of second convex blocks (1222) formed on the negative electrode active material layer (122) and a plurality of second concave blocks (1221) arranged opposite to the second convex blocks (1222); The first protrusion (1121) is arranged opposite to the second groove (1221), and the second protrusion (1222) is arranged opposite to the first groove (1122).

2. The battery cell (100) according to claim 1, characterized in that: The first convex block (1121) is provided on one side of the positive electrode active material layer (112) away from the positive electrode current collector (111), and the first groove (1122) is provided on the other side of the positive electrode active material layer (112) away from the positive electrode current collector (111); The second groove (1221) is provided on one side of the negative electrode active material layer (122) away from the negative electrode current collector (121), and the second protrusion (1222) is provided on the other side of the negative electrode active material layer (122) away from the negative electrode current collector (121).

3. The battery cell (100) according to claim 2, characterized in that: The height H1 of the first bump (1121) is greater than the height H2 of the second bump (1222), and satisfies: 0.4H1≤H2≤0.95H1; and / or, The depth H3 of the first groove (1122) is greater than the depth H4 of the second groove (1221), and satisfies: 0.4H3≤H4≤0.95H3.

4. The battery cell (100) according to claim 2, characterized in that: The cross section of any one of the first protrusion (1121), the first groove (1122), the second protrusion (1222) and the second groove (1221) is circular; and / or The diameter D1 of the first bump (1121) is greater than the diameter D2 of the second bump (1222), and satisfies: D2<0.95D1; and / or The diameter D3 of the first groove (1122) is greater than the diameter D4 of the second groove (1221), and satisfies: D4<0.95D3.

5. The battery cell (100) according to any one of claims 1 to 4, characterized in that: The positive electrode sheet (110) and the negative electrode sheet (120) are stacked and wound to form the battery cell (100) with at least two layers; The battery cell (100) comprises a plane area and an arc-shaped area, the first protrusion (1121) and the second groove (1221) located in the plane area at least partially overlap in the thickness direction of the battery cell (100), and the proportion of the overlapping area to the plane area is less than 80%.

6. The battery cell (100) according to claim 5, characterized in that: The first protrusion (1121) and the second groove (1221) located in the arc-shaped area at least partially overlap in the thickness direction of the battery cell (100), and the proportion of the overlapping area to the arc-shaped area is less than 50%.

7. The battery cell (100) according to any one of claims 1 to 4, characterized in that: A plurality of the first protrusions (1121) are arranged at intervals along the width direction and the length direction of the positive electrode active material layer (112), and a plurality of the second grooves (1221) are arranged at intervals along the width direction and the length direction of the negative electrode active material layer (122); The center distance L1 between two adjacent first bumps (1121) is smaller than the center distance L2 between two adjacent second bumps (1222), and satisfies: 1.1≤L2 / L1≤3.

8. The battery cell (100) according to claim 7, characterized in that: The center distance L1 between two adjacent first bumps (1121) and the center distance L2 between two adjacent second bumps (1222) satisfy: 1.5≤L2 / L1≤2.

5.

9. The battery cell (100) according to claim 3, characterized in that: The silicon content W in the negative electrode active material layer (122) satisfies the following relationship between the height H1 of the first bump (1121) and the silicon content W: 1200W≤H1≤3000W; and / or The height H2 of the second bump (1222) and the silicon content W satisfy: 800W≤H2≤2500W.

10. The battery cell (100) according to claim 5, characterized in that: In the length direction of the positive electrode sheet (110), at least one level of the positive electrode sheet (110) has a first space-avoiding area (115) and a first non-space-avoiding area (116), the first protrusion (1121) is located in the first non-space-avoiding area (116), and the first space-avoiding area (115) is not provided with the first protrusion (1121).

11. The battery cell (100) according to claim 10, characterized in that: The distance between the first air avoidance area (115) and the first non-air avoidance area (116) is greater than or equal to the width of the first layer of the positive electrode sheet (110), and less than or equal to the sum of the widths of the first three layers of the positive electrode sheet (110), wherein the first layer of the positive electrode sheet (110) is located in the central layer of the battery cell (100).

12. The battery cell (100) according to any one of claims 1 to 4, characterized in that: The positive electrode sheet (110) further comprises a positive electrode ear (113) and a first protective tape (114), wherein the distance between the edge of the first protrusion (1121) and the area where the positive electrode ear (113) is arranged is greater than or equal to 1 mm and less than or equal to 30 mm; and / or, The distance between the edge of the first protrusion (1121) and the first protective tape (114) is greater than or equal to 1 mm and less than or equal to 30 mm; and / or, The negative electrode sheet (120) further comprises a negative electrode ear (123) and a second protective tape (124), wherein the distance between the edge of the second groove (1221) and the area where the negative electrode ear (123) is arranged is greater than or equal to 1 mm and less than or equal to 30 mm; and / or, The distance between the second groove (1221) and the second protective tape (124) is greater than or equal to 1 mm and less than or equal to 30 mm.

13. The battery cell (100) according to claim 10, characterized in that: Along the width direction of the positive electrode sheet (110), the distance between the first protrusion (1121) facing the upper edge of the positive electrode sheet (110) and the upper edge of the positive electrode sheet (110) is greater than or equal to 1 mm and less than or equal to 20 mm; and / or, The distance between the first protrusion (1121) facing the lower edge of the positive electrode sheet (110) and the lower edge of the positive electrode sheet (110) is greater than or equal to 1 mm and less than or equal to 20 mm; and / or, Along the width direction of the negative electrode sheet (120), the distance between the second groove (1221) facing the upper edge of the negative electrode sheet (120) and the upper edge of the negative electrode sheet (120) is greater than or equal to 1 mm and less than or equal to 20 mm; and / or, The distance between the second groove (1221) facing the lower edge of the negative electrode sheet (120) and the lower edge of the negative electrode sheet (120) is greater than or equal to 1 mm and less than or equal to 20 mm.

14. The battery cell (100) according to claim 13, characterized in that: Along the width direction of the positive electrode sheet (110), the distance between the first protrusion (1121) facing the upper edge of the positive electrode sheet (110) and the upper edge of the positive electrode sheet (110) is greater than or equal to 3 mm and less than or equal to 10 mm; and / or, The distance between the first protrusion (1121) facing the lower edge of the positive electrode sheet (110) and the lower edge of the positive electrode sheet (110) is greater than or equal to 3 mm and less than or equal to 10 mm; and / or, Along the width direction of the negative electrode sheet (120), the distance between the second groove (1221) facing the upper edge of the negative electrode sheet (120) and the upper edge of the negative electrode sheet (120) is greater than or equal to 3 mm and less than or equal to 15 mm; and / or, The distance between the second groove (1221) facing the lower edge of the negative electrode sheet (120) and the lower edge of the negative electrode sheet (120) is greater than or equal to 3 mm and less than or equal to 15 mm.

15. The battery cell (100) according to any one of claims 1 to 4, characterized in that: The tensile strength of the positive electrode current collector (111) is greater than or equal to 280 MPa; and / or, The ratio of the height of the first convex block (1121) to the tensile strength of the positive electrode current collector (111) is greater than or equal to 0.2 and less than or equal to 0.6; and / or, The tensile strength of the negative electrode current collector (121) is greater than or equal to 400 MPa; and / or, The ratio of the height of the second protrusion (1222) to the tensile strength of the negative electrode current collector (121) is greater than or equal to 0.1 and less than or equal to 0.

4.

16. The battery cell (100) according to claim 9, characterized in that: The negative electrode active material layer (122) comprises a silicon-carbon composite material and / or a silicon-oxygen composite material, wherein the percentage content W1 of silicon element in the negative electrode active material layer (122) is 3%≤W1≤50%.

17. The battery cell (100) according to claim 16, characterized in that: The silicon-carbon composite material comprises a porous carbon matrix, silicon crystal grains located in the pores of the porous carbon matrix, and a carbon layer located on the surface of the porous carbon matrix.

18. The battery cell (100) according to claim 17, characterized in that: The carbon layer includes openings arranged corresponding to the pores of the porous carbon matrix.

19. The battery cell (100) according to claim 18, characterized in that: The specific surface area of ​​the silicon-carbon composite material is 0.5 m 2 / g-10m 2 / g; and / or, The particle size Dv50 of the silicon-carbon composite material is 6 μm-15 μm; and / or, The powder resistivity of the silicon-carbon composite material is in the range of 0.1 Ω·cm-1000 Ω·cm; and / or, The silicon content in the silicon-carbon composite material is 30%-75%.

20. A battery, characterized in that: Comprising the battery cell (100) as claimed in any one of claims 1 to 19.

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