Battery cell, battery assembly and electric equipment thereof

Abstract

The utility model provides a battery cell, a battery assembly and electric equipment. The battery cell comprises a pole piece and a diaphragm, and the diaphragm comprises one of a convex part or a groove part; the pole piece comprises the other one of a convex part or a groove part, at least part of the convex part is located in the groove part, and a gap exists between the convex part and the groove part. At least part of the lug boss is positioned in the groove part, so that the tightness of the combination of the pole piece and the diaphragm is increased; the gap between the convex part and the groove part reserves a space for the expansion of the pole piece, so that the volume expansion of the battery in the circulating process is reduced; the lamination between the pole piece and the diaphragm can be achieved without hot pressing, so that the process cost is reduced, and the production efficiency is improved; and the gap between the convex part and the groove part can provide a space for electrolyte storage, so that the electrolyte retention performance of the battery cell is improved.

Description

Technical Field

[0001] The utility model belongs to the field of urban rail transit, and specifically relates to a battery core, a battery assembly and electrical equipment. Background Art

[0002] The development of power batteries determines the future of new energy vehicles, and the improvement of power battery energy density largely determines the development of power batteries. Considering the driving range, the new energy vehicle industry has increasingly urgent requirements for high-energy-density batteries to enter the actual implementation stage. As the requirements for long driving range and high energy density of power batteries become higher and higher, the requirements for safety performance are also getting higher and higher. In the battery, the main function of the diaphragm is to ensure the effective isolation between the positive and negative electrodes and have a certain mechanical strength. In order to improve the energy density of the battery cell, the length of the battery cell is currently increasing (>300mm), and as the battery cell continues to expand in a cycle, the diaphragm and the electrode will be misaligned, and the safety hazards will increase significantly; the current glue-coated diaphragm can significantly improve the bonding performance between the positive and negative electrodes, and the coated PVDF layer can maintain good bonding performance with the positive and negative electrodes, thereby significantly inhibiting the thickness expansion of the battery cell during the cycle, thereby improving the thickness consistency of the battery cell.

[0003] In the existing battery cell system, the binder in the positive electrode sheet is mainly PVDF series, which has the same polarity as the PVDF coating applied on the glue-coated separator, so the bonding performance between the positive electrode sheet and the glue-coated separator is good; while the binder in the negative electrode sheet is mainly styrene-butadiene latex (SBR) system. Due to the interaction between the non-polar SBR and polar PVDF molecular chains, the bonding performance between the negative electrode sheet and the glue-coated separator is poor. In addition, as the battery cycles, PVDF will swell in the electrolyte, reducing the bonding force between the positive electrode sheet, the separator and the negative electrode sheet. In order to increase the bonding force, the amount of the glue layer will be further increased, but it will increase the internal resistance of the battery and deteriorate the cycle performance. Utility Model Content

[0004] In view of the problems existing in the prior art, the present application provides a battery cell, a battery assembly and an electrical device.

[0005] In order to solve the above problems, the present application provides the following technical solutions.

[0006] In a first aspect, the present application provides a battery cell comprising a pole piece and a diaphragm, wherein the diaphragm comprises one of a protrusion or a groove; the pole piece comprises the other of a protrusion or a groove, at least a portion of the protrusion is located in the groove, and there is a gap between the protrusion and the groove.

[0007] In some embodiments, there are a plurality of the protrusions and the grooves, and the protrusions and the grooves are arranged in an array.

[0008] In some embodiments, the plurality of protrusions are one or more of a cylinder, a cube, and a cuboid, and / or the plurality of grooves are one or more of a cylinder, a cube, and a cuboid.

[0009] In some embodiments, the diaphragm includes a protrusion and a groove, and the pole piece includes a protrusion and a groove; at least part of the protrusion of the diaphragm is located in the groove of the pole piece, and at least part of the protrusion of the pole piece is located in the groove of the diaphragm; there is a gap between the protrusion of the diaphragm and the groove of the pole piece, and / or there is a gap between the protrusion of the pole piece and the groove of the diaphragm.

[0010] In some embodiments, the pole piece and the diaphragm are stacked, and in the stacking direction of the pole piece and the diaphragm, the height H1 of the plurality of protrusions satisfies: 0.3 μm≤H1≤50 μm, and the depth H2 of the plurality of grooves satisfies: 0.3 μm≤H2≤50 μm.

[0011] In some embodiments, in the thickness direction of the battery cell, H1=H2, and there are gaps around the protrusion.

[0012] In some embodiments, the maximum dimension of the orthographic projection of the top of the protrusion on the plane perpendicular to the thickness direction of the diaphragm is W1; the maximum dimension of the orthographic projection of the bottom of the groove on the plane perpendicular to the thickness direction of the diaphragm is W2, satisfying: 1μm≤W1≤1mm; 1μm≤W2≤1mm, 0≤W2-W1≤5%W1.

[0013] In some embodiments, the diaphragm includes a base film and a functional layer, the functional layer is disposed on the base film, and the protrusion or the groove is located on the functional layer.

[0014] In some embodiments, the thickness Ha of the functional layer satisfies: Ha≤50 μm.

[0015] In some embodiments, the pole piece includes a current collector and an active material layer disposed on the current collector, and the groove portion or the protrusion portion is located on the active material layer.

[0016] In some embodiments, the pole piece and the diaphragm are stacked, and in the stacking direction of the pole piece and the diaphragm, the height of the protrusion is H1, the depth of the groove is H2, and the thickness Hb of the active material layer satisfies: H1≤Hb≤200μm or H2≤Hb≤200μm.

[0017] In some embodiments, the functional layer includes an organic coating and / or an inorganic coating; the organic coating includes one of polyvinylidene fluoride, polymethyl methacrylate, and polyacrylonitrile; the inorganic coating includes one of aluminum oxide, boehmite, and silicon oxide.

[0018] In some embodiments, the base film includes one of polypropylene, polyethylene, non-woven fabric, cellulose, and polyimide.

[0019] In some embodiments, the electrode sheet includes a positive electrode sheet and / or a negative electrode sheet.

[0020] In a second aspect, the present application provides a battery assembly comprising the battery cell described in the first aspect.

[0021] In a third aspect, an electrical device is provided, comprising the battery cell described in the first aspect or the battery assembly described in the second aspect.

[0022] The battery cell provided by the present application has the following technical effects: (1) at least part of the protrusion is located in the groove, which increases the tightness of the connection between the electrode and the diaphragm; (2) the gap between the protrusion and the groove reserves space for the expansion of the electrode, reducing the volume expansion of the battery during the cycle; (3) the bonding between the electrode and the diaphragm can be achieved without hot pressing, which reduces the process cost and improves the production efficiency; (4) the gap between the protrusion and the groove can provide space for electrolyte storage, improving the liquid retention performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0026] Figure 1It is a schematic diagram of the structure of the battery cell in some embodiments of the utility model;

[0027] Figure 2 It is a schematic diagram of the battery cell structure in some embodiments of the utility model.

[0028] Description of reference numerals: A: base film; B: functional layer; C: active material layer; D: current collector; DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0030] In a first aspect, the utility model provides a battery cell comprising a pole piece and a diaphragm, wherein the diaphragm comprises one of a protrusion or a groove; the pole piece comprises the other of a protrusion or a groove, at least a portion of the protrusion is located in the groove, and there is a gap between the protrusion and the groove.

[0031] Specifically, one of the diaphragm including a protrusion or a groove and the other of the pole piece including a protrusion and a groove means that the diaphragm includes a protrusion and the pole piece includes a groove; or the diaphragm includes a groove and the pole piece includes a protrusion. At least part of the protrusion is located in the groove means that the diaphragm and the pole piece are connected to each other through the connection between the protrusion and the groove; there is a gap between the protrusion and the groove means that after the protrusion is at least partly located in the groove, the bottom of the groove and / or the surrounding area of ​​the groove are not in contact with the protrusion, and there is a gap.

[0032] The diaphragm may include a type of protrusion or groove, or a type of diaphragm including only a protrusion or groove, or a type of diaphragm including both a protrusion and a groove; similarly, the pole piece may include a type of protrusion and groove, or a type of diaphragm including only a protrusion and groove, or a type of diaphragm including both a protrusion and a groove.

[0033] The battery cell provided in the present application has the following effects: (1) at least part of the protrusion is located in the groove, which increases the tightness of the combination of the electrode and the diaphragm; (2) the gap between the protrusion and the groove reserves space for the expansion of the electrode, reducing the volume expansion of the battery during the cycle; (3) the bonding between the electrode and the diaphragm can be achieved without hot pressing, reducing the process cost and improving the production efficiency; (4) the gap between the protrusion and the groove can provide space for electrolyte storage, improving the liquid retention performance of the battery cell.

[0034] In some embodiments, there are a plurality of the protrusions and the grooves, and the protrusions and the grooves are arranged in an array.

[0035] Specifically, the plurality of protrusions and grooves means that the diaphragm includes a plurality of protrusions or a plurality of grooves, the pole piece includes a plurality of protrusions or a plurality of grooves, the number of protrusions and grooves is equal, the protrusions and grooves fit each other, the protrusions are located in the grooves, and the protrusions and grooves are combined with each other; the protrusions and grooves are arranged in an array, which means that a plurality of protrusions and a plurality of grooves are arranged in rows and columns, the intervals between two adjacent protrusions are equal, and the intervals between two adjacent grooves are equal.

[0036] Specifically, multiple protrusions are located in multiple grooves, which can further enhance the bonding strength between the diaphragm and the pole piece; multiple protrusions and multiple grooves are arranged in an array, which can control the uniformity of bonding between the diaphragm and the pole piece at each position and enhance the overall bonding strength between the diaphragm and the pole piece.

[0037] In some preferred embodiments, the plurality of protrusions are one or more of a cylinder, a cube, and a cuboid, and / or the plurality of grooves are one or more of a cylinder, a cube, and a cuboid.

[0038] Specifically, the multiple raised portions being one or more of a cylinder, a cube, or a cuboid means that a single raised portion is individually a cylinder, a cube, or a cuboid; the multiple groove portions being one or more of a cylinder, a cube, or a cuboid means that a single second raised portion is individually a cylinder, a cube, or a cuboid.

[0039] The shapes of the protrusion and the groove can be the same or different; the shapes of the protrusion and the protrusion can be the same or different; the shapes of the groove and the groove can be the same or different. The protrusion and the groove can be cylindrical, cubic, or rectangular, which can be controlled by prefabricating a mold of a specific shape. The protrusion and the groove are formed by pressing the mold, which is convenient for forming on the diaphragm and the electrode, and the preparation is simple.

[0040] In some embodiments, the diaphragm includes a protrusion and a groove, and the pole piece includes a protrusion and a groove; at least part of the protrusion of the diaphragm is located in the groove of the pole piece, and at least part of the protrusion of the pole piece is located in the groove of the diaphragm; there is a gap between the protrusion of the diaphragm and the groove of the pole piece, and / or there is a gap between the protrusion of the pole piece and the groove of the diaphragm.

[0041] Specifically, protrusions and grooves are formed on both the diaphragm and the pole piece, and the protrusions and grooves on the diaphragm are matched with and combined with the grooves and protrusions on the pole piece, thereby further enhancing the degree of bonding between the diaphragm and the pole piece. At the same time, there is a gap between the protrusions of the diaphragm and the grooves of the pole piece, and / or there is a gap between the protrusions of the pole piece and the grooves of the diaphragm. The gap provides space for the storage of electrolyte, improves the liquid retention performance of the battery cell, reserves space for the expansion of the pole piece, and alleviates the degradation of battery performance and the shortened life of the battery cell due to the expansion of the pole piece.

[0042] In some embodiments, the pole piece and the diaphragm are stacked, and in the stacking direction of the pole piece and the diaphragm, the height H1 of the plurality of protrusions satisfies: 0.3 μm≤H1≤50 μm, and the depth H2 of the plurality of grooves satisfies: 0.3 μm≤H2≤50 μm.

[0043] Specifically, the height of the protrusion refers to the average distance from the top of the protrusion to the bottom of the protrusion in the stacking direction of the pole piece and the diaphragm, and the depth of the groove refers to the average distance from the bottom of the groove to the surface of the diaphragm or pole piece.

[0044] Specifically, the height of the protrusion may be, but is not limited to, 0.3μm, 0.5μm, 0.8μm, 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, and 50μm; the depth of the groove may be, but is not limited to, 0.3μm, 0.5μm, 0.8μm, 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, and 50μm. The greater the height of the protrusion and the depth of the groove, the larger the contact area between the protrusion and the groove, and the tighter the combination of the diaphragm and the electrode; the smaller the height of the protrusion and the depth of the groove, the smoother the surface of the electrode and the diaphragm, and the better the safety performance of the battery cell. When the height of the protrusion and the depth of the groove are within the above range, both the bonding strength between the diaphragm and the battery and the safety performance of the battery can be guaranteed.

[0045] In some embodiments, H1=H2, and there is a gap around the protrusion.

[0046] Specifically, the height of the protrusion is equal to the depth of the groove, and the top of the protrusion and the bottom of the groove can contact each other, which can better ensure the mechanical properties of the diaphragm and the electrode and enhance the tightness of the combination of the electrode and the diaphragm; there are gaps in the surrounding area of ​​the groove, which can provide storage space for the electrolyte and reserve space for the expansion of the electrode, thereby improving the safety performance of the battery.

[0047] In some embodiments, the maximum dimension of the orthographic projection of the top of the protrusion on the plane perpendicular to the thickness direction of the diaphragm is W1; the maximum dimension of the orthographic projection of the bottom of the groove on the plane perpendicular to the thickness direction of the diaphragm is W2, satisfying: 1μm≤W1≤1mm; 1μm≤W2≤1mm, 0≤W2-W1≤5%W1.

[0048] Specifically, the maximum dimension of the orthographic projection of the top of the raised portion on the plane perpendicular to the thickness direction of the diaphragm is W1, that is, the longest line segment formed by connecting any two points in the orthographic projection is W1; the maximum dimension of the orthographic projection of the bottom of the groove portion on the plane perpendicular to the thickness direction of the diaphragm is W2, that is, the longest line segment formed by connecting any two points in the orthographic projection is W2.

[0049] Specifically, the maximum dimension W1 of the orthographic projection of the top of the protrusion on the plane perpendicular to the thickness direction of the diaphragm may be but is not limited to 1μm, 10μm, 50μm, 100μm, 200μm, 500μm, 800μm, or 1mm; the maximum dimension W2 of the orthographic projection of the bottom of the groove on the plane perpendicular to the thickness direction of the diaphragm may be but is not limited to 1μm, 10μm, 50μm, 100μm, 200μm, 500μm, 800μm, or 1mm.

[0050] Specifically, W2-W1≤5% W1 can ensure that the dimensional difference between the protrusion and the groove is controlled within a smaller range, the diaphragm and the pole piece are more tightly combined, and the diaphragm and the pole piece are not easy to move relative to each other; controlling the relationship between W1 and W2 can make a gap between the protrusion and the groove, and enhance the tightness of the combination between the pole piece and the diaphragm.

[0051] Specifically, 0≤W2-W1 means that the maximum dimension of the protrusion is less than or equal to the maximum dimension of the groove, so that the protrusion can be better accommodated in the groove and there can be a gap between the protrusion and the groove. While enhancing the bonding force between the diaphragm and the electrode, space is reserved for the storage of the electrolyte and the expansion of the electrode during the circulation process, thereby improving the safety performance of the battery.

[0052] In some embodiments, the diaphragm includes a base film and a functional layer, the functional layer is disposed on the base film, and the protrusion or the groove is located on the functional layer.

[0053] Specifically, the functional layer is coated on one or both sides of the base film, which can enhance the liquid retention capacity of the separator and improve the electrochemical performance and life of the battery.

[0054] In some embodiments, the thickness Ha of the functional layer satisfies: Ha≤10 μm.

[0055] Specifically, the thickness Ha of the functional layer satisfies: Ha≤50 μm. The thickness Ha of the functional layer within this range can ensure that the functional layer has a certain mechanical strength, thereby enhancing the mechanical properties of the diaphragm.

[0056] In some embodiments, the pole piece includes a current collector and an active material layer disposed on the current collector, and the groove portion or the protrusion portion is located on the active material layer.

[0057] In some embodiments, the pole piece and the diaphragm are stacked, and in the stacking direction of the pole piece and the diaphragm, the height of the protrusion is H1, the depth of the groove is H2, and the thickness Hb of the active material layer satisfies: H1≤Hb≤200μm or H2≤Hb≤200μm.

[0058] Specifically, the thickness Hb of the active material layer satisfies: H1≤Hb≤200 μm or H2≤Hb≤200 μm. The thickness of the active material layer within this range can better ensure the performance of the electrode sheet and enhance the overall electrochemical performance of the battery.

[0059] In some embodiments, the functional layer includes an organic coating and / or an inorganic coating; the organic coating includes one of polyvinylidene fluoride, polymethyl methacrylate, and polyacrylonitrile; the inorganic coating includes one of aluminum oxide, boehmite, and silicon oxide.

[0060] In some embodiments, the base film includes one of polypropylene, polyethylene, non-woven fabric, cellulose, and polyimide.

[0061] In some embodiments, the electrode sheet includes a positive electrode sheet and / or a negative electrode sheet.

[0062] Specifically, the positive electrode sheet and the negative electrode sheet are both the positive electrode sheet and the negative electrode sheet conventionally used in batteries; the positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder, and the negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder; the positive and negative electrode active materials, conductive agents, and binders are all existing technologies and will not be elaborated here.

[0063] In a second aspect, the present application provides a battery assembly, including the battery cell described in the first aspect;

[0064] Specifically, the battery assembly includes a battery pack or a battery module.

[0065] In a third aspect, the present application provides an electrical device, comprising the battery cell described in the first aspect or the battery assembly described in the second aspect.

[0066] Specifically, the electrical equipment may include but is not limited to electric vehicles, mobile phones, tablet computers, laptop computers, wearable devices (watches, bracelets), digital cameras, etc.

[0067] The battery cell provided by the present application has the following technical effects: (1) at least part of the protrusion is located in the groove, which increases the tightness of the connection between the electrode and the diaphragm; (2) the gap between the protrusion and the groove reserves space for the expansion of the electrode, reducing the volume expansion of the battery during the cycle; (3) the bonding between the electrode and the diaphragm can be achieved without hot pressing, which reduces the process cost and improves the production efficiency; (4) the gap between the protrusion and the groove can provide space for electrolyte storage, improving the liquid retention performance of the battery cell.

[0068] The present invention is further described in detail below through embodiments.

[0069] Example 1

[0070] This embodiment is used to illustrate the battery cell, battery assembly and electrical equipment disclosed in the utility model, and includes the following steps:

[0071] (1) Preparation of the diaphragm: The diaphragm includes a base film and a functional layer, the diaphragm is a polyethylene (PE) film, and the functional layer is an aluminum oxide coating. The functional layer includes a protrusion, the height H1 of the protrusion is 5 μm, the maximum dimension W1 of the orthographic projection of the top of the protrusion on a plane perpendicular to the thickness direction of the diaphragm is 500 μm, and the thickness of the functional layer is 10 μm.

[0072] (2) Preparation of positive electrode sheet: The positive electrode sheet includes a current collector and a positive electrode active material layer. The current collector is aluminum foil. The positive electrode active material layer includes 90% of positive electrode active material (specifically lithium iron phosphate), 6% of conductive agent (specifically carbon nanotubes); 4% of binder (specifically PVDF); the positive electrode active material, conductive agent, and binder are made into a slurry and coated on the aluminum foil, and then dried and rolled to obtain a positive electrode sheet. The positive electrode sheet includes a groove portion, the depth H2 of the groove portion is 5μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the diaphragm is 500μm, and the thickness of the active material layer is 100μm.

[0073] (3) Preparation of negative electrode sheet: The negative electrode sheet includes a current collector and a negative electrode active material layer. The current collector is copper foil. The negative electrode active material layer includes 90% negative electrode active material (specifically natural graphite), 5% conductive agent (specifically acetylene black), and 5% binder (specifically SBR). The negative electrode active material, conductive agent, and binder are made into a slurry and coated on the copper foil, and then dried and rolled to obtain a negative electrode sheet. The negative electrode sheet includes a groove portion, the depth H2 of the groove portion is 5μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 500μm, and the thickness of the active material layer is 100μm.

[0074] (4) Preparation of lithium-ion batteries: The positive electrode sheets, separators, and negative electrode sheets are stacked, shaped, and hot-pressed in sequence, and then loaded into an aluminum battery shell. The battery cells are placed in an oven to dry excess moisture, and an appropriate amount of electrolyte is injected. The cells are then subjected to the steps of wetting, formation, aging, and capacity separation in sequence to produce a battery.

[0075] Example 2

[0076] The difference between Example 2 and Example 1 is that the parameter settings are different, as follows, and the rest are the same as Example 1.

[0077] (1) Preparation of the diaphragm: The diaphragm includes a protrusion, the height H1 of the protrusion is 1 μm, the maximum dimension W1 of the orthographic projection of the top of the protrusion on a plane perpendicular to the thickness direction of the diaphragm is 500 μm, and the thickness of the functional layer is 10 μm.

[0078] (2) Preparation of positive electrode sheet: The positive electrode sheet includes a groove portion, the depth H2 of the groove portion is 1 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 500 μm, and the thickness of the active material layer is 100 μm.

[0079] (3) Preparation of negative electrode sheet: The negative electrode sheet includes a groove portion, the depth H2 of the groove portion is 1 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 500 μm, and the thickness of the active material layer is 100 μm.

[0080] Example 3

[0081] The difference between Example 3 and Example 1 is that the parameter settings are different, as follows, and the rest are the same as Example 1.

[0082] (1) Preparation of the diaphragm: The diaphragm includes a protrusion, the height H1 of the protrusion is 50 μm, the maximum dimension W1 of the orthographic projection of the top of the protrusion on a plane perpendicular to the thickness direction of the diaphragm is 500 μm, and the thickness of the functional layer is 10 μm.

[0083] (2) Preparation of positive electrode sheet: The positive electrode sheet includes a groove portion, the depth H2 of the groove portion is 50 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 500 μm, and the thickness of the active material layer is 100 μm.

[0084] (3) Preparation of negative electrode sheet: The negative electrode sheet includes a groove portion, the depth H2 of the groove portion is 30 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 500 μm, and the thickness of the active material layer is 100 μm.

[0085] Example 4

[0086] The difference between Example 4 and Example 1 is that the parameter settings are different, as follows, and the rest are the same as Example 1.

[0087] (1) Preparation of the diaphragm: The diaphragm includes a protrusion, the height H1 of the protrusion is 5 μm, the maximum dimension W1 of the orthographic projection of the top of the protrusion on a plane perpendicular to the thickness direction of the diaphragm is 1 μm, and the thickness of the functional layer is 10 μm.

[0088] (2) Preparation of positive electrode sheet: The positive electrode sheet includes a groove portion, the depth H2 of the groove portion is 5 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 1 μm, and the thickness of the active material layer is 100 μm.

[0089] (3) Preparation of negative electrode sheet: The negative electrode sheet includes a groove portion, the depth H2 of the groove portion is 5 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 1 μm, and the thickness of the active material layer is 100 μm.

[0090] Example 5

[0091] The difference between Example 5 and Example 1 is that the parameter settings are different, as follows, and the rest are the same as Example 1.

[0092] (1) Preparation of the diaphragm: The diaphragm includes a protrusion, the height H1 of the protrusion is 5 μm, the maximum dimension W1 of the orthographic projection of the top of the protrusion on a plane perpendicular to the thickness direction of the diaphragm is 1 mm, and the thickness of the functional layer is 10 μm.

[0093] (2) Preparation of positive electrode sheet: The positive electrode sheet includes a groove portion, the depth H2 of the groove portion is 5 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 1 mm, and the thickness of the active material layer is 100 μm.

[0094] (3) Preparation of negative electrode sheet: The negative electrode sheet includes a groove portion, the depth H2 of the groove portion is 5 μm, the maximum dimension W2 of the orthographic projection of the bottom of the groove portion on a plane perpendicular to the thickness direction of the separator is 1 mm, and the thickness of the active material layer is 100 μm.

[0095] Comparative Example 1

[0096] The difference between Comparative Example 1 and Example 1 is that the lithium ion battery has no protrusions and grooves, and the rest is the same as Comparative Example 1.

[0097] Test method:

[0098] (1) Peeling force: The separator and electrode are removed from the battery, and the separator and electrode are cut into samples of 30 mm*100 mm. The separator and electrode are flipped 180° by 20 mm. With the help of a tensile testing machine, the upper clamp holds the separator end and the lower clamp holds the electrode end. The tensile testing machine moves at a speed of 100 mm / s and moves 50 mm. The average peeling strength is recorded, which is the peeling force between the electrode and the separator.

[0099] (2) Liquid retention amount: The positive and negative electrodes and the separator are assembled into a 60mm*70mm soft-pack battery. 6ml of electrolyte is injected. After immersion for 30 days, the battery is disassembled to measure the amount of free electrolyte. Liquid retention amount = amount of injected electrolyte - amount of free electrolyte.

[0100] (3) Parameters of raised and recessed parts: The diaphragm and pole piece were cut into samples of 10 mm*10 mm. The morphology and size of the target area were photographed and measured using an electron microscope.

[0101] Table 1 Parameter settings and performance test results of various embodiments and comparative examples

[0102]

[0103]

[0104] In summary, from the data of Examples 1 to 5 and Comparative Example 1, by providing protrusions and grooves on the diaphragm and the electrode, the protrusions are accommodated in the grooves, which can enhance the bonding ability between the diaphragm and the electrode, and enhance the tightness of the bonding between the electrode and the diaphragm; and there is a gap between the protrusions and the grooves, which can store electrolyte, thereby enhancing the battery's liquid retention capacity.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery cell, characterized in that: It includes a pole piece and a diaphragm, wherein the diaphragm includes one of a protrusion or a groove; the pole piece includes the other of a protrusion or a groove, at least part of the protrusion is located in the groove, and there is a gap between the protrusion and the groove.

2. The battery cell according to claim 1, characterized in that: There are a plurality of the protrusions and the grooves, and the protrusions and the grooves are arranged in an array.

3. The battery cell according to claim 2, characterized in that: The plurality of protrusions are one or more of a cylinder, a cube, and a cuboid, and / or the plurality of grooves are one or more of a cylinder, a cube, and a cuboid.

4. The battery cell according to claim 1, characterized in that: The diaphragm includes a protrusion and a groove, and the pole piece includes a protrusion and a groove; at least part of the protrusion of the diaphragm is located in the groove of the pole piece, and at least part of the protrusion of the pole piece is located in the groove of the diaphragm; There is a gap between the protrusion of the diaphragm and the groove of the pole piece, and / or there is a gap between the protrusion of the pole piece and the groove of the diaphragm.

5. The battery cell according to claim 1, characterized in that: The pole piece and the diaphragm are stacked, and in the stacking direction of the pole piece and the diaphragm, the height H1 of the protrusion satisfies: 0.3 μm≤H1≤50 μm, and the depth H2 of the groove satisfies: 0.3 μm≤H2≤50 μm.

6. The battery cell according to claim 5, characterized in that: H1=H2, there is a gap around the protrusion.

7. The battery cell according to claim 1, characterized in that: The size of the orthographic projection of the top of the protrusion on the plane perpendicular to the thickness direction of the diaphragm is W1; the maximum dimension of the orthographic projection of the bottom of the groove on the plane perpendicular to the thickness direction of the diaphragm is W2, satisfying: 1μm≤W1≤1mm; 1μm≤W2≤1mm, 0≤W2-W1≤5%W1.

8. The battery cell according to claim 1, characterized in that: The diaphragm includes a base film and a functional layer, wherein the functional layer is disposed on the base film, and the protrusion or the groove is located on the functional layer.

9. The battery cell according to claim 8, characterized in that: The thickness Ha of the functional layer satisfies: 0≤Ha≤50μm.

10. The battery cell according to claim 1, characterized in that: The pole piece includes a current collector and an active material layer disposed on the current collector, and the groove portion or the protrusion portion is located on the active material layer.

11. The battery cell according to claim 10, characterized in that: The pole piece and the diaphragm are stacked, and in the stacking direction of the pole piece and the diaphragm, the height of the protrusion is H1, the depth of the groove is H2, and the thickness Hb of the active material layer satisfies: H1≤Hb≤200μm or H2≤Hb≤200μm.

12. The battery cell according to claim 8, characterized in that: The functional layer includes an organic coating and / or an inorganic coating; the organic coating includes one of polyvinylidene fluoride, polymethyl methacrylate, and polyacrylonitrile; the inorganic coating includes one of aluminum oxide, boehmite, and silicon oxide.

13. The battery cell according to claim 8, characterized in that: The base film includes one of polypropylene, polyethylene, non-woven fabric, cellulose, and polyimide.

14. The battery cell according to claim 1, characterized in that: The electrode sheet includes a positive electrode sheet and / or a negative electrode sheet.

15. A battery assembly, characterized in that: A battery cell comprising the battery cell described in any one of claims 1 to 13.

16. An electrical equipment, characterized in that: It comprises the battery cell according to any one of claims 1 to 14 or the battery assembly according to claim 15.

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