Battery pole piece and battery

Abstract

The utility model relates to the technical field of secondary batteries, in particular to a battery pole piece and a battery. The battery pole piece comprises a current collector, an active material layer arranged on the current collector and a protective layer located in the same plane with the active material layer, the protective layer comprises an R-angle protective layer and a pole piece edge protective layer, the R-angle protective layer covers an R-angle area of a bending area when the battery pole piece is wound to manufacture an electrode assembly, and the pole piece edge protective layer covers the R-angle area of the bending area when the battery pole piece is wound to manufacture the electrode assembly. The pole piece edge protection layers extend along the length direction of the current collector and are respectively arranged on two opposite sides of the active material layer; and the R-angle protection layer and the pole piece edge protection layer are of fence-shaped structures formed by a plurality of protection strips. According to the utility model, the pole piece edge protection layer and the R corner protection layer are arranged in the fence shape, so that the infiltration rate and the infiltration effect of electrolyte are remarkably improved, and the problem that the electrolyte at the R corner and in the battery pole piece is infiltrated poorly is solved.

Description

Technical Field

[0001] This utility model relates to the field of secondary battery technology, specifically to a battery electrode and a battery. Background Technology

[0002] During the electrolyte filling process of a secondary battery, the electrolyte is injected through the top filling port. Due to gravity, most of the electrolyte flows through the gaps around the electrode assembly and accumulates at the bottom, resulting in a large amount of free electrolyte remaining at the bottom. A small portion of the electrolyte then slowly permeates upwards from the bottom to the electrode sheets through capillary pressure, while an even smaller portion wets the electrode sheets from top to bottom. If the wetting time is insufficient, the electrode sheets in the middle and upper parts of the electrode assembly will not be fully wetted by the electrolyte. Similarly, uneven stress and high compaction at the radius (R-corner) result in smaller internal gaps and insufficient space for electrode rebound, also leading to difficulty in electrolyte wetting. This not only causes uneven current density distribution and instability of the solid electrolyte interphase (SEI) film, affecting battery life, but also hinders lithium-ion transport in the electrolyte, causing localized lithium plating at the negative electrode and high internal resistance, leading to a series of safety and battery kinetic problems such as severe localized heating and rapid material deactivation. Utility Model Content

[0003] Therefore, the technical problem to be solved by this utility model is to overcome the defects of poor electrolyte wetting at the R-corner and inside the battery electrode of existing secondary batteries, thereby providing a battery electrode and battery that solves the above problems.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] In a first aspect, this utility model provides a battery electrode sheet, comprising: a current collector, an active material layer disposed on the current collector, and a protective layer located in the same plane as the active material layer. The protective layer includes a corner protection layer and an electrode edge protection layer. The corner protection layer covers the corner region of the bending area when the battery electrode sheet is wound to manufacture an electrode assembly. The electrode edge protection layer extends along the length direction of the current collector and is respectively disposed on opposite sides of the active material layer. Both the corner protection layer and the electrode edge protection layer are fence-like structures composed of several protective strips.

[0006] Preferably, a gap is provided between the electrode edge protection layer and / or the R-corner protection layer and the active material layer.

[0007] Preferably, the width of the gap is no more than 1 mm.

[0008] Preferably, the width of the electrode edge protective layer is 4-6 mm, the width of each protective strip in the electrode edge protective layer is 0.8-1.2 mm, and the interval between two adjacent protective strips is 0.3-0.5 mm.

[0009] Preferably, the width of each protective strip in the electrode edge protective layer is 1 mm, and the interval between two adjacent protective strips is 0.5 mm.

[0010] Preferably, the width of each protective strip in the R-corner protective layer is 0.5-0.7mm, and the interval between two adjacent protective strips is 0.3-0.5mm.

[0011] Preferably, the width of each protective strip in the R-corner protective layer is 0.6 mm, and the interval between two adjacent protective strips is 0.4 mm.

[0012] Preferably, the battery electrode is a positive electrode.

[0013] And / or, the material of the protective strip is an inorganic porous material.

[0014] Preferably, the material of the protective strip is at least one of zeolite molecular sieve, calcium silicate, and ceramic material.

[0015] Secondly, this utility model provides a battery, including the aforementioned battery electrode.

[0016] The technical solution of this utility model has the following advantages:

[0017] 1. A battery electrode, comprising: a current collector, an active material layer disposed on the current collector, and a protective layer located in the same plane as the active material layer, the protective layer including a corner protection layer and an electrode edge protection layer, the corner protection layer covering the corner region of the bending area during the winding of the battery electrode to manufacture an electrode assembly, the electrode edge protection layer extending along the length direction of the current collector and respectively disposed on opposite sides of the active material layer; both the corner protection layer and the electrode edge protection layer are fence-like structures composed of several protective strips. This invention significantly improves the electrolyte wetting rate and wetting effect by setting the electrode edge protection layer extending along the length direction of the current collector and respectively disposed on opposite sides of the active material layer, and the corner protection layer at the corner of the bending area during the winding of the battery electrode to manufacture an electrode assembly, in a fence-like configuration. Specifically, during electrolyte injection, the electrolyte is injected through the injection port at the top of the battery. The grid-like protective layer ensures that some electrolyte is wetted and adsorbed in the edge protective layer above the battery electrode and the corner protective layer on both sides. Simultaneously, due to gravity and the presence of gaps, some electrolyte flows to the bottom of the battery. Since there is also an edge protective layer at the bottom of the battery electrode, its grid-like design further enhances the adsorption and wettability of the electrolyte, preventing electrolyte accumulation at the bottom of the battery. Furthermore, based on the above design, a structure enclosed by protective layers on all four sides can be formed. The electrolyte wets the inner side of the electrode from the top, bottom, left, and right protective layers, thus ensuring complete wettability of the battery electrode in a short time. This significantly improves the wettability rate and effect of the electrolyte, solving problems such as lithium plating and low capacity caused by poor wettability at the corners and inside the battery electrode, which obstructs the migration path of lithium ions between the positive and negative electrodes.

[0018] 2. In the battery electrode provided by this utility model, a gap is set between the electrode edge protective layer and / or R-corner protective layer and the active material layer. If the gap is not maintained, the protective layer slurry and the active material layer slurry will inevitably intermingle and penetrate each other during coating, and the part of the electrode that is intermingled cannot exert its capacity. Based on this, setting a gap between the two improves the overall capacity of the battery to a certain extent.

[0019] 3. In the battery electrode provided by this utility model, the width of the edge protective layer of the electrode is 4-6 mm. In the fence-like protective layer covering both sides of the active material layer in the width direction, the width of each protective strip is 0.8-1.2 mm, and the interval between two adjacent protective strips is 0.3-0.5 mm. If the protective layer is fully coated on both sides of the active material layer in the width direction, or if the width of each protective strip is greater than 1.2 mm and the interval between each protective strip is less than 0.3 mm, the protective layer and the current collector have different tensile strengths and elongations. This can easily lead to vertical creases along the extension direction of the current collector at the boundary between the fully coated protective layer or the overly dense fence-like protective layer and the current collector during rolling, increasing the risk of brittle fracture due to tensile tension on the current collector. By setting multiple gaps, the difference in tensile tension caused by the different tensile strengths and elongations of the protective layer and the current collector can be shared, avoiding stress concentration at the boundary between the outermost part of the protective layer and the current collector, and reducing the risk of vertical creases and strip breakage.

[0020] 4. In the battery electrode provided by this utility model, the width of each protective strip in the grid-like protective layer covering the R-corner is 0.5-0.7mm, and the interval between two adjacent protective strips is 0.3-0.5mm. This is because after the battery electrode is bent, it will undergo significant bending deformation. The space at the R-corner is small, and after the battery is filled with electrolyte, small solvent molecules in the electrolyte will penetrate into the protective layer at the R-corner, causing the protective layer to swell. If the R-corner is fully coated with a protective layer, or if the width of each protective strip is greater than 0.7mm and the interval between each protective strip is less than 0.3mm, the narrow space at the R-corner cannot accommodate the volume increase caused by the swelling of the protective layer, leaving no space for the electrode to rebound, which easily leads to battery bulging. The grid-like coating of the protective layer at the R-corner, with a 0.3-0.5mm interval between each protective strip, can alleviate the volume change caused by the swelling of the protective layer and reduce the risk of battery bulging. If the coating width of each protective strip is less than 0.5mm and the interval between each protective strip is greater than 0.5mm, the smaller protective layer coating, although it improves the wetting effect of electrolyte at the R-corner to some extent, cannot quickly absorb a sufficient amount of electrolyte, affecting the electrolyte wetting speed and effect during battery filling. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of the battery electrode sheet of this utility model;

[0023] Figure 2 This is a schematic diagram of the cross-section of the battery electrode sheet in the width direction of this utility model.

[0024] Explanation of reference numerals in the attached figures: 1-current collector; 2-active material layer; 3-R-corner protective layer; 4-electrode edge protective layer. Detailed Implementation

[0025] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0026] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0028] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1

[0030] This embodiment provides a positive electrode for a battery, the overall structure of which is as follows: Figure 1 As shown, the cross-sectional structure of the electrode in the width direction is as follows: Figure 2As shown, it includes: a current collector 1, an active material layer 2 disposed on the current collector 1, and a protective layer located in the same plane as the active material layer 2. The protective layer includes an R-corner protective layer 3 and an electrode edge protective layer 4. The R-corner protective layer 3 covers the R-corner area of ​​the bending area when the battery electrode is wound to manufacture the electrode assembly. The electrode edge protective layer 4 extends along the length direction of the current collector 1 and is respectively disposed on opposite sides of the active material layer 2. Both the R-corner protective layer 3 and the electrode edge protective layer 4 are fence-like structures composed of several protective strips.

[0031] The R-corner protective layer 3 and the electrode edge protective layer 4 are collectively referred to as the protective layer. A gap is provided between the electrode edge protective layer 4 and the active material layer 2. A gap may also be provided between the R-corner protective layer 3 and the active material layer 2. The gap width is not higher than 1 mm, and in this embodiment it is 0.1 mm.

[0032] The width of the electrode edge protection layer 4 is 4-6mm, and in this embodiment it is 5mm; in the electrode edge protection layer 4, each protective strip can extend along the length direction of the current collector 1 (e.g., Figure 1 As shown in the figure, it can also extend along the width direction of the current collector 1 (not shown in the figure); the width of each protective strip is 0.8-1.2mm, and 1mm in this embodiment; the interval between two adjacent protective strips is 0.3-0.5mm, and 0.5mm in this embodiment.

[0033] In the R-corner protective layer 3, each protective strip can extend along the width direction of the current collector 1 (e.g., Figure 1 As shown in the figure, it can also extend along the length of the current collector 1 (not shown in the figure); the width of each protective strip is 0.5-0.7mm, and in this embodiment it is 0.6mm; the interval between two adjacent protective strips is 0.3-0.5mm, and in this embodiment it is 0.4mm.

[0034] Example 2

[0035] This embodiment provides a positive electrode for a battery, which is basically the same as that in embodiment 1. The difference is that in the edge protection layer 4 of the electrode, the width of each protective strip is 0.8 mm and the interval between two adjacent protective strips is 0.3 mm; in the R-corner protection layer 3, the width of each protective strip is 0.5 mm and the interval between two adjacent protective strips is 0.3 mm.

[0036] Example 3

[0037] This embodiment provides a positive electrode for a battery, which is basically the same as that in embodiment 1. The difference is that in the edge protection layer 4 of the electrode, the width of each protective strip is 1.2 mm and the interval between two adjacent protective strips is 0.5 mm; in the R-corner protection layer 3, the width of each protective strip is 0.7 mm and the interval between two adjacent protective strips is 0.5 mm.

[0038] It should be noted that the materials of the protective layers (R-corner protective layer 3 and electrode edge protective layer 4) in this utility model are all conventional inorganic porous materials in the field. For example, they can be any one of zeolite molecular sieves, calcium silicate and ceramic materials, or they can be a mixture of the above materials.

[0039] It should be noted that this utility model does not specify the cathode material for the cathode active material layer 2. It can be a conventional ternary cathode material or a conventional lithium iron phosphate cathode material, etc.

[0040] This invention provides a battery electrode, comprising: a current collector 1, an active material layer 2 disposed on the current collector 1, and a protective layer located in the same plane as the active material layer 2. The protective layer includes a corner protection layer 3 and an electrode edge protection layer 4. The corner protection layer 3 covers the corner region of the bending area during the winding of the battery electrode assembly. The electrode edge protection layer 4 extends along the length of the current collector 1 and is disposed on opposite sides of the active material layer 2. Both the corner protection layer 3 and the electrode edge protection layer 4 are fence-like structures composed of several protective strips. This invention significantly improves the electrolyte wetting rate and wetting effect by setting the electrode edge protection layer 4 extending along the length of the current collector and disposed on opposite sides of the active material layer 2, and the corner protection layer 3 at the corner of the bending area during the winding of the battery electrode assembly, in a fence-like configuration. Specifically, during electrolyte injection, the electrolyte is injected through the injection port at the top of the battery. The grid-like protective layer allows some electrolyte to be wetted and adsorbed in the electrode edge protective layer 4 above the battery electrode and the R-corner protective layers 3 on both sides. Simultaneously, due to gravity and the presence of gaps, some electrolyte flows to the bottom of the battery. Since there is also an electrode edge protective layer 4 at the bottom of the battery electrode, its grid-like design further improves the adsorption and wettability of the electrolyte, preventing electrolyte accumulation at the bottom of the battery. Furthermore, based on the above design, a structure enclosed by protective layers on all four sides can be formed. The electrolyte wets the inner side of the electrode from the top, bottom, left, and right protective layers, thus ensuring complete wettability of the battery electrode in a short time. This significantly improves the wetting rate and effect of the electrolyte, solving problems such as lithium plating and low capacity caused by poor wetting at the R-corners and inside the battery electrode, which obstructs the migration path of lithium ions between the positive and negative electrodes.

[0041] In the battery electrode provided by this utility model, the R-corner protective layer 3 and the electrode edge protective layer 4 are collectively referred to as the protective layer. A gap is provided between the electrode edge protective layer 4 and the active material layer 2. A gap can also be provided between the R-corner protective layer 3 and the active material layer 2. If no gap is maintained, during coating, the protective layer slurry and the active material layer slurry will inevitably intermingle and penetrate each other, resulting in the portion of the electrode that is intermingled failing to achieve its capacity. Therefore, providing a gap between the two layers improves the overall capacity performance of the battery to a certain extent.

[0042] In the battery electrode provided by this utility model, the width of the electrode edge protective layer 4 is 4-6mm; the width of each protective strip in the electrode edge protective layer 4 is 0.8-1.2mm, and the interval between two adjacent protective strips is 0.3-0.5mm. If the electrode edge protective layer 4 or each protective strip in the electrode edge protective layer 4 is wider than 1.2mm and the interval between each protective strip is less than 0.3mm, due to the different tensile strengths and elongations of the protective layer and the current collector, vertical creases are likely to appear along the extension direction of the current collector 1 at the boundary between the fully coated protective layer or the overly dense grid-like protective layer and the current collector during rolling, increasing the risk of brittle fracture due to tensile tension on the current collector. By setting multiple gaps, the difference in tensile tension caused by the different tensile strengths and elongations of the protective layer and the current collector can be shared, avoiding stress concentration at the boundary between the outermost part of the protective layer and the current collector, and reducing the risk of vertical creases and strip breakage.

[0043] In the battery electrode provided by this utility model, the width of each protective strip in the R-corner protective layer 3 is 0.5-0.7 mm, and the interval between two adjacent protective strips is 0.3-0.5 mm. This is because after the battery electrode is bent, it will undergo significant bending deformation. The space at the R-corner is small, and after the battery is filled with electrolyte, small solvent molecules in the electrolyte will penetrate into the protective layer 3 at the R-corner, causing the protective layer to swell. If the R-corner is fully coated with a protective layer, or if the width of each protective strip in the R-corner protective layer 3 is greater than 0.7 mm and the interval between each protective strip is less than 0.3 mm, the narrow space at the R-corner cannot accommodate the volume increase caused by the swelling of the protective layer. There is no space for the electrode to rebound, which can easily lead to battery bulging. The grid-like coating of the protective layer 3 at the R-corner, with a 0.3-0.5 mm interval between each protective strip, can alleviate the volume change caused by the swelling of the protective layer and reduce the risk of battery bulging. If the coating width of each protective strip is less than 0.5mm and the interval between each protective strip is greater than 0.5mm, the smaller protective layer coating, although it improves the wetting effect of electrolyte at the R-corner to some extent, cannot quickly absorb a sufficient amount of electrolyte, affecting the electrolyte wetting speed and effect during battery filling.

[0044] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A battery electrode, characterized in that, include: The current collector (1), the active material layer (2) disposed on the current collector (1), and the protective layer located in the same plane as the active material layer (2) are provided. The protective layer includes an R-corner protective layer (3) and an electrode edge protective layer (4). The R-corner protective layer (3) covers the R-corner area of ​​the bending area when the battery electrode is wound to manufacture the electrode assembly. The electrode edge protective layer (4) extends along the length direction of the current collector (1) and is disposed on opposite sides of the active material layer (2). The R-corner protective layer (3) and the electrode edge protective layer (4) are both fence-like structures composed of several protective strips.

2. The battery electrode according to claim 1, characterized in that, A gap is provided between the electrode edge protection layer (4) and / or the R-corner protection layer (3) and the active material layer (2).

3. The battery electrode according to claim 2, characterized in that, The width of the gap is no more than 1 mm.

4. The battery electrode according to claim 1, characterized in that, The electrode edge protection layer (4) has a width of 4-6 mm, and each protective strip in the electrode edge protection layer (4) has a width of 0.8-1.2 mm, with a spacing of 0.3-0.5 mm between two adjacent protective strips.

5. The battery electrode according to claim 4, characterized in that, The width of each protective strip in the electrode edge protection layer (4) is 1 mm, and the interval between two adjacent protective strips is 0.5 mm.

6. The battery electrode according to claim 1, characterized in that, The width of each protective strip in the R-corner protective layer (3) is 0.5-0.7mm, and the interval between two adjacent protective strips is 0.3-0.5mm.

7. The battery electrode according to claim 6, characterized in that, The width of each protective strip in the R-corner protective layer (3) is 0.6 mm, and the interval between two adjacent protective strips is 0.4 mm.

8. The battery electrode according to claim 1, characterized in that, The battery electrode is a positive electrode. And / or, the material of the protective strip is an inorganic porous material.

9. The battery electrode according to claim 8, characterized in that, The protective strip is made of zeolite molecular sieve, calcium silicate, or ceramic material.

10. A battery, characterized in that, Includes the battery electrode as described in any one of claims 1-9.

Images