Battery monomer pole piece, battery monomer, battery and electric equipment

Abstract

The utility model provides a battery monomer pole piece, a battery monomer, a battery and electric equipment, and relates to the technical field of batteries. The battery monomer pole piece comprises a current collector and an active material layer, the active material layer is arranged on at least one surface of the current collector, the active material layer comprises a middle area and edge areas located on the two sides of the middle area in the first direction, each edge area comprises a thinning layer, and a conducting layer is arranged on the surface, away from the current collector, of each thinning layer. The surface, deviating from the current collector, of the conductive layer is flush with the surface, deviating from the current collector, of the middle area, lithium precipitation is not prone to occurring, and the safety risk can be reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell pole piece, a battery cell, a battery and an electrical device. Background Art

[0002] During the charge and discharge cycle of lithium batteries, the active materials at the edge of the battery are often subjected to greater stress, resulting in battery capacity decay and shortened life. Therefore, by thinning the edge of the battery, the impact of the edge effect on battery performance can be reduced, thereby improving the battery's cycle life and energy density.

[0003] However, due to the thinning and thickening of the battery edges, the thickness at this position is thinner than that in the center section of the battery cell, resulting in poor contact and a longer lithium ion transmission path. Lithium deposition and formation of lithium dendrites are prone to occur, and lithium dendrites can pierce the diaphragm, causing an internal short circuit and posing a greater safety risk. Utility Model Content

[0004] The objectives of the present application include, for example, providing a battery cell pole piece, a battery cell and a battery, which are not prone to lithium plating and can reduce safety risks.

[0005] The purpose of the present application also includes providing an electrical device whose batteries are not prone to lithium plating, thereby reducing the safety risk of the device.

[0006] This application can be implemented as follows:

[0007] In a first aspect, the present application provides a battery cell pole piece, comprising a current collector and an active material layer, wherein the active material layer is arranged on at least one surface of the current collector, and the active material layer comprises a middle region and edge regions located on both sides of the middle region along a first direction; the edge region comprises a skived layer, and the surface of the skived layer facing away from the current collector is covered with a conductive layer, and the surface of the conductive layer facing away from the current collector is flush with the surface of the middle region facing away from the current collector.

[0008] Optionally, the thickness of the skived layer gradually decreases from the middle area to the edge area.

[0009] Optionally, along the extension direction of the active material layer, the cross-section of the thinned layer is triangular or trapezoidal, and the extension direction of the active material layer is perpendicular to the first direction.

[0010] Optionally, one end of the conductive layer away from the middle region exceeds the skived layer and contacts the current collector.

[0011] Optionally, the conductive layer is conductive glue.

[0012] Optionally, the width of the skived layer along the first direction is 1-5 mm.

[0013] Optionally, the battery cell pole piece is a positive pole piece, and the thickness of the current collector is 6-20 μm; or, the battery cell pole piece is a negative pole piece, and the thickness of the current collector is 5-15 μm.

[0014] In a second aspect, the present application further provides a battery cell, comprising a shell and an electrode assembly disposed in the shell, wherein the electrode assembly comprises the above-mentioned battery cell electrode sheet.

[0015] In a third aspect, the present application also provides a battery comprising a plurality of the above-mentioned battery cells.

[0016] In a fourth aspect, the present application also provides an electrical device, including the above-mentioned battery.

[0017] The beneficial effects of the battery cell pole piece, battery cell, battery and electrical equipment of the present application include, for example: in order to prevent lithium plating from occurring and reduce safety risks, a battery cell pole piece is designed, the battery cell pole piece includes a current collector and an active material layer, the active material layer is arranged on at least one surface of the current collector, the active material layer includes a middle area and edge areas located on both sides of the middle area along a first direction, the edge area is flush with the middle area; the edge area includes a skived layer, and the surface of the skived layer facing away from the current collector is covered with a conductive layer. Since the conductive layer is arranged on the skived layer, the problem of lithium plating caused by the long lithium ion transmission path due to the thin thickness of the skived layer is solved, and the safety risk is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A top view of a battery cell pole piece in an embodiment of the present application;

[0020] Figure 2 This is a first cross-sectional view of a battery cell pole piece in an embodiment of the present application;

[0021] Figure 3 This is a second cross-sectional view of a battery cell pole piece in an embodiment of the present application.

[0022] Icon: 1-current collector; 11-ear; 2-active material layer; 21-main layer; 22-thinning layer; 3-conductive layer. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution 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, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the present application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, it is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the utility model product is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0027] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0028] It should be noted that, in the absence of conflict, the features in the embodiments of the present application may be combined with each other.

[0029] The inventor of the present application found that due to the thinning and thickness reduction at the edge of the battery, the thickness at this position is thinner than that at the center of the battery cell, resulting in poor contact and a long lithium ion transmission path, which is prone to lithium deposition and formation of lithium dendrites. The lithium dendrites will pierce the diaphragm, causing an internal short circuit and posing a greater safety risk. The embodiments of the present application provide a battery cell pole piece that is not prone to lithium deposition and can reduce safety risks.

[0030] Please refer to Figure 1-Figure 3 , Figure 1 A top view of a battery cell pole piece in an embodiment of the present application; Figure 2 This is a first cross-sectional view of a battery cell pole piece in an embodiment of the present application; Figure 3 This is a second cross-sectional view of a battery cell pole piece in an embodiment of the present application.

[0031] The battery cell pole piece includes a current collector 1 and an active material layer 2, the active material layer 2 is arranged on at least one surface of the current collector 1, the active material layer 2 includes a middle area and edge areas located on both sides of the middle area along a first direction, the edge area includes a skived layer 22, a conductive layer 3 is arranged on the surface of the skived layer 22 away from the current collector 1, and the surface of the conductive layer 3 away from the current collector 1 is flush with the surface of the middle area away from the current collector 1.

[0032] It should be pointed out that the current collector 1 has two opposite surfaces along its own thickness direction, and the active material layer 2 is arranged on one of the surfaces of the current collector 1, or the active material layer 2 is arranged on both opposite surfaces of the current collector 1 along its own thickness direction; the active material layer 2 includes a main layer 21 and a thinning layer 22 arranged on both sides of the main layer 21 along the first direction x; the two edge regions are symmetrically arranged on both sides of the middle region, the conductive layer 3 is covered on the thinning layer 22, and is located on the side of the thinning layer 22 away from the current collector 1; the sum of the thickness of the conductive layer 3 and the thinning layer 22 on the edge region is equal to the thickness of the main layer 21 on the middle region; the portion of the current collector 1 extending out of the thinning layer 22 in the first direction x is the pole ear 11.

[0033] Since the conductive layer 3 is arranged on the thinned layer 22, the sum of the thickness of the thinned layer 22 and the conductive layer 3 in the edge area is equal to the thickness of the main layer 21 in the middle area, which solves the problem of lithium plating caused by the long lithium ion transmission path due to the thin thickness of the thinned layer 22 and reduces the safety risk.

[0034] In an optional embodiment, the thickness of the skived layer 22 gradually decreases from the middle area to the edge area.

[0035] On a single active material layer 2, the thickness of one of the thinned layers 22 gradually decreases in the direction from the middle region to the edge region on one side. Since the two thinned layers 22 are symmetrically arranged on both sides of the main layer 21, the thickness of the other thinned layer 22 gradually decreases in the direction from the middle region to the edge region on the other side. By arranging the thinned layer 22 with gradually decreasing thickness at the edge of the active material layer 2, the influence of the edge effect on the battery performance can be reduced.

[0036] In an optional embodiment, along the extending direction of the active material layer 2, the cross section of the thinned layer 22 is triangular or trapezoidal, and the extending direction of the active material layer 2 is perpendicular to the first direction.

[0037] It should be noted that the cross section of the skived layer 22 along the extension direction of the active material layer 2 is a triangle or a trapezoid; of course, it can be understood that the cross section of the skived layer 22 along the extension direction of the active material layer 2 can also be other polygons.

[0038] In an optional embodiment, one end of the conductive layer 3 away from the middle region exceeds the skived layer 22 and contacts the current collector 1 .

[0039] It should be noted that, in the first direction x, the conductive layer 3 exceeds the skived layer 22 by 2 mm, and the portion of the conductive layer 3 exceeding the skived layer 22 is in contact with the current collector 1 .

[0040] In another optional embodiment, at one end of the conductive layer 3 away from the middle region, the conductive layer 3 is flush with the skived layer 22 , and at this time the conductive layer 3 is not in contact with the current collector 1 .

[0041] In an optional embodiment, the conductive layer 3 is conductive glue.

[0042] It should be noted that the conductive adhesive can be a binder that has conductive properties, such as macromolecular pyridine substances, etc. The conductive adhesive can also be mainly composed of a binder and a conductive substance, and the binder accounts for no less than 50%.

[0043] When the battery cell pole piece is a positive pole piece, the binder may be one or more materials such as epoxy resin, phenolic resin, polyurethane, thermoplastic resin, polyimide, etc., and the conductive substance may be one or more materials such as Al, Zn, Fe, Au, Ag, Ni powder, etc.; when the battery cell pole piece is a negative pole piece, the binder may be one or more materials such as epoxy resin, phenolic resin, polyurethane, thermoplastic resin, polyimide, etc.; the conductive substance may be one or more materials such as Cu, Au, Ag powder and graphite, etc.

[0044] In an optional embodiment, the width of the skived layer 22 along the first direction x is 1-5 mm.

[0045] Exemplarily, the width of the skived layer 22 along the first direction x is 1 mm, 3 mm or 5 mm. It can be understood that the width of the skived layer 22 along the first direction x can be selected within the above range according to actual working conditions.

[0046] In an optional embodiment, the lengths of the main layer 21 , the skived layer 22 and the conductive layer 3 are consistent along the second direction y, wherein the second direction y is perpendicular to the first direction x.

[0047] In an optional embodiment, the current collector 1 may be made of materials such as copper foil, aluminum foil, and nickel foil, which have good electrical conductivity.

[0048] In an optional embodiment, when the battery cell pole piece is a positive electrode pole piece, the active material layer includes a binder and a positive electrode active substance, and the positive electrode active substance includes but is not limited to lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium titanate or a mixture thereof, and the current collector 1 can be made of aluminum foil.

[0049] When the battery cell pole piece is a negative pole piece, the active material layer includes a binder and a negative electrode active material, and the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB for short), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel-structured lithiated TiO2-Li4Ti5O12, and Li-Al alloys, and the current collector 1 can be made of copper foil.

[0050] In an optional embodiment, the battery cell pole piece is a positive pole piece, and the thickness of the current collector 1 is 6-20 μm.

[0051] Exemplarily, the thickness of the current collector 1 is 6 μm, 10 μm, 15 μm or 20 μm. It can be understood that when the battery cell pole piece is a positive pole piece, the thickness of the current collector 1 can be selected within the above range according to actual working conditions.

[0052] In an optional embodiment, the battery cell pole piece is a negative pole piece, and the thickness of the current collector 1 is 5-15 μm.

[0053] Exemplarily, the thickness of the current collector 1 is 6 μm, 10 μm, 15 μm or 20 μm. It can be understood that when the battery cell pole piece is a negative pole piece, the thickness of the current collector 1 can be selected within the above range according to actual working conditions.

[0054] An embodiment of the present application further provides a battery cell, comprising a shell and an electrode assembly disposed in the shell, wherein the electrode assembly comprises the above-mentioned battery cell pole piece.

[0055] In the process of manufacturing a battery cell, after the active material layer 2 is coated, the active material layer 2 is dried and rolled to form a main layer 21 and a skived layer 22, and then a conductive layer 3 is coated on the skived layer 22 so that the sum of the thickness of the conductive layer 3 and the skived layer 22 is equal to the thickness of the main layer 21, and then dried and rolled to form a battery cell pole piece, and then a battery cell is formed through winding, hot pressing, shelling, liquid injection, formation and other processes.

[0056] An embodiment of the present application also provides a battery, comprising a plurality of the above-mentioned battery cells.

[0057] The battery may be a battery pack or a battery module, and the battery pack or the battery module includes a plurality of the above-mentioned battery cells.

[0058] An embodiment of the present application further provides an electrical device, comprising the above-mentioned battery.

[0059] The above-mentioned battery cells, batteries, and electrical equipment are all made of the above-mentioned battery cell pole pieces, and have basically the same technical effects as the battery cell pole pieces, which will not be described in detail here.

[0060] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A battery cell pole piece, characterized in that: The invention comprises a current collector (1) and an active material layer (2), wherein the active material layer (2) is arranged on at least one surface of the current collector (1), the active material layer (2) comprises a middle region and edge regions located on both sides of the middle region along a first direction, the edge regions comprise a skived layer (22), the surface of the skived layer (22) facing away from the current collector (1) is covered with a conductive layer (3), and the surface of the conductive layer (3) facing away from the current collector (1) is flush with the surface of the middle region facing away from the current collector (1).

2. The battery cell pole piece according to claim 1, characterized in that: The thickness of the skived layer (22) gradually decreases from the middle area to the edge area.

3. The battery cell pole piece according to claim 1, characterized in that: Along the extension direction of the active material layer (2), the cross-section of the thinned layer (22) is triangular or trapezoidal, and the extension direction of the active material layer (2) is perpendicular to the first direction.

4. The battery cell pole piece according to claim 1, characterized in that: One end of the conductive layer (3) away from the middle region exceeds the skived layer (22) and contacts the current collector (1).

5. The battery cell pole piece according to claim 1, characterized in that: The conductive layer (3) is conductive glue.

6. The battery cell pole piece according to claim 1, characterized in that: The width of the skived layer (22) along the first direction is 1-5 mm.

7. The battery cell pole piece according to claim 1, characterized in that: The battery cell pole piece is a positive pole piece, and the thickness of the current collector (1) is 6-20 μm; Alternatively, the battery cell pole piece is a negative pole piece, and the thickness of the current collector (1) is 5-15 μm.

8. A battery cell, characterized in that: It comprises a shell and an electrode assembly arranged in the shell, and the electrode assembly comprises the battery cell pole piece according to any one of claims 1 to 7.

9. A battery, characterized in that: The invention comprises a plurality of battery cells according to claim 8.

10. An electrical device, characterized in that: A battery comprising the battery of claim 9.

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