Electrode and battery cell

Abstract

The present application provides a pole piece and a battery cell, the pole piece includes a current collector and two active material layers, the two active material layers are respectively arranged on both sides of the current collector in the thickness direction, and at least one of the active material layers has a wetting area; wherein, there is a gap between the surface of the wetting area facing the current collector and the current collector, and / or, a groove is provided on the surface of the wetting area facing away from the current collector, wherein the gap passes through at least one surface of the active material layer along its own extension direction. Through this arrangement, the contact area between the active material layer and the electrolyte is increased by utilizing the gap between the wetting area and the current collector or the groove of the wetting area, which is conducive to increasing the infiltration speed of the electrolyte, and increasing the infiltration degree of the electrolyte and the active material layer, thereby increasing the reaction activity of the active material and helping to improve the energy density of the battery.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage devices, and in particular to a pole piece and a battery cell. Background Art

[0002] Lithium-ion batteries have been widely used in the market due to their advantages of long cycle life, high energy density, environmental protection and safety.

[0003] Taking wound battery cells as an example, in order to allow the electrolyte to fully infiltrate between the positive and negative active materials, the thickness of the positive and negative active materials is generally relatively thin. This requires that the number of layers of the battery cell winding must be increased to meet the battery capacity requirements, which indirectly increases the proportion of materials such as current collectors and diaphragms that do not provide battery energy, resulting in a decrease in the proportion of positive and negative active materials in a certain space, thereby reducing the energy density of the battery.

[0004] Therefore, how to ensure sufficient wetting between the electrolyte and the active material and improve the battery energy density has become an urgent problem to be solved. Utility Model Content

[0005] In view of this, the present application provides a pole piece and a battery cell, which can improve the degree of infiltration of electrolyte and active material and improve the energy density of the battery.

[0006] Specifically, the following technical solutions are included:

[0007] In a first aspect, an embodiment of the present application provides a pole piece, the pole piece comprising a current collector and two active material layers, the two active material layers are respectively arranged on both sides of the current collector in a thickness direction, and at least one of the active material layers has a wetting area;

[0008] There is a gap between the side surface of the wetting area facing the current collector and the current collector, and / or a groove is provided on the side surface of the wetting area away from the current collector, wherein the gap penetrates at least one surface of the active material layer along its extension direction.

[0009] In an optional embodiment, in at least one of the active material layers, the length direction of the groove is parallel to the width direction of the current collector.

[0010] In an optional embodiment, there are multiple grooves, and at least two adjacent grooves have different extension lengths.

[0011] In an optional embodiment, there are multiple grooves, and in one of the active material layers, the length direction of the groove is parallel to the width direction of the current collector; in another active material layer, the length direction of the groove is parallel to the length direction of the current collector.

[0012] In an optional embodiment, the two active material layers both have the grooves, and the grooves in the two active material layers are staggered in the length direction of the current collector.

[0013] In an optional embodiment, the two active material layers both have the grooves, and the grooves in the two active material layers are symmetrically arranged along the thickness direction of the current collector.

[0014] In an optional embodiment, the current collector is provided with a first connection hole, the first connection hole penetrates the current collector along the thickness direction of the current collector, and the two active material layers are connected through the first connection hole to fill the first connection hole.

[0015] In an optional embodiment, the current collector is provided with a second connection hole, the second connection hole penetrates the current collector along the thickness direction of the current collector, and the second connection hole penetrates at least one of the active material layers.

[0016] In an optional embodiment, the groove penetrates the active material layer along the thickness direction of the current collector, and the groove is spaced apart from an edge of the active material layer.

[0017] In an optional embodiment, the depth of the groove is less than the thickness of the active material layer, and the groove penetrates the active material layer along its length direction.

[0018] In an optional embodiment, the current collector has a folding region, in which the current collector is bent in a wave-like shape along its own length direction, so that the gap is generated between the surface of the side of the wetting region facing the current collector and the current collector.

[0019] In a second aspect, an embodiment of the present application provides a battery cell, comprising a shell, a diaphragm, a positive electrode sheet and a negative electrode sheet, wherein the diaphragm, the positive electrode sheet and the negative electrode sheet are accommodated in the shell, the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet and / or the negative electrode sheet are the electrodes provided by any embodiment of the first aspect.

[0020] The beneficial effects of the technical solution provided in the embodiments of the present application include at least: by setting a wetting area in at least one active material layer, utilizing the gap between the wetting area and the current collector or the groove in the wetting area, the contact area between the active material layer and the electrolyte is increased, which is beneficial to increase the infiltration speed of the electrolyte, and increase the infiltration degree of the electrolyte and the active material layer, thereby increasing the reaction activity of the active material and helping to improve the energy density of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only 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 work.

[0022] Figure 1 A top view of a pole piece provided for one embodiment of the present application;

[0023] Figure 2 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0024] Figure 3 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0025] Figure 4 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0026] Figure 5 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0027] Figure 6 A top view of a pole piece provided for one embodiment of the present application;

[0028] Figure 7 A top view of a pole piece provided for one embodiment of the present application;

[0029] Figure 8 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0030] Fig. 9 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0031] Fig.10 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0032] Fig.11 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0033] Fig.12 A top view of a pole piece provided for one embodiment of the present application;

[0034] Fig.13 A cross-sectional view of a pole piece provided for one embodiment of the present application;

[0035] Fig.14 A cross-sectional view of a battery cell provided in accordance with an embodiment of the present application;

[0036] Fig.15A cross-sectional view of a battery cell provided in another embodiment of the present application.

[0037] The reference numerals in the figures represent respectively:

[0038] 10-pole piece; 1-current collector; 11-folding area; 12-first connection hole; 13-second connection hole; 2-active material layer; 3-wetting area; 31-groove; 32-gap;

[0039] 100-shell; 200-diaphragm; 300-positive electrode plate; 400-negative electrode plate; 500-electrolyte; 600-ear.

[0040] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions 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 this application.

[0042] The directional nouns involved in the embodiments of the present application, such as "upper", "lower", "side", etc., are generally represented by Figure 1 The relative relationship of the orientation shown in the figure is used as the basis, and these orientation terms are used only to more clearly describe the relationship between structures, not to describe absolute orientation. When the product is placed in different postures, the orientation may change, for example, "up" and "down" may be interchangeable.

[0043] Unless otherwise defined, all technical terms used in the embodiments of the present application have the same meanings as those generally understood by those of ordinary skill in the art. Some technical terms appearing in the embodiments of the present application are explained below.

[0044] In order to make the technical solutions and advantages of the present application more clear, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0045] like Figures 1 to 12 As shown, the embodiment of the present application provides a pole piece 10, which is a positive pole piece 300 or a negative pole piece 400. Specifically, the pole piece 10 is applied to a battery cell, which can be a wound battery cell or a stacked battery cell, and the battery cell includes a shell 100, which has a receiving cavity, and the pole piece 10 is received in the receiving cavity, and the receiving cavity is filled with an electrolyte 500.

[0046] Specifically, the pole piece 10 includes a current collector 1 and two active material layers 2, the two active material layers 2 are respectively arranged on both sides of the current collector 1 in the thickness direction, and at least one active material layer 2 has a wetting area 3. For example, Figure 2 and Figure 5 As shown, both active material layers 2 are provided with grooves 31; or, for example Figure 3 As shown, only one of the active material layers 2 is provided with a recess 31 .

[0047] like Figure 1 As shown, the left-right direction in the figure is the length direction of the current collector 1, and the up-down direction in the figure is the width direction of the current collector 1; Figure 2 As shown, the left-right direction in the figure is the length direction of the current collector 1 , and the up-down direction in the figure is the thickness direction of the current collector 1 .

[0048] A gap 32 is provided between the surface of the wetting region 3 facing the current collector 1 and the current collector 1, and / or a groove 31 is provided on the surface of the wetting region 3 facing away from the current collector 1, wherein the gap 32 penetrates at least one surface of the active material layer 2 along its extension direction.

[0049] like Figure 4 As shown, since the void 32 penetrates at least one surface of the active material layer 2 along its own extension direction, the void 32 forms a flow channel for the electrolyte 500, so that the electrolyte 500 can enter the void 32, thereby fully infiltrating the active material in the active material layer 2. Exemplarily, the void 32 extends along the width direction of the current collector 1, the void 32 is a blind hole structure, and the void 32 penetrates one of the surfaces of the active material layer 2 in the width direction of the current collector 1; Exemplarily, the void 32 extends along the width direction of the current collector 1, the void 32 is a through-hole structure, and the void 32 penetrates two opposite surfaces of the active material layer 2 in the width direction of the current collector 1, so that the electrolyte 500 can flow from one end of the void 32 to the other end.

[0050] The groove 31 is processed by laser etching, mechanical drilling, etc. In the cross section of the pole piece 10, the shape of the groove 31 can be semicircular, triangular, trapezoidal, rectangular, elliptical, etc., for example Figure 1 As shown, the outline of the groove 31 is rectangular. It can be understood that the cross section of the pole piece 10 is a cross section obtained by cutting with a plane perpendicular to the length direction of the current collector 1 .

[0051] The groove 31 may penetrate at least one of the two opposite surfaces of the active material layer 2 , or the groove 31 may be located between the two opposite surfaces of the active material layer 2 .

[0052] Optionally, the total opening area of ​​the grooves 31 in the active material layer 2 is smaller than or equal to the total area of ​​the active material layer 2 to ensure that the total amount of active material is sufficient.

[0053] In the prior art, the active material layer 2 of the pole piece 10 of the lithium-ion battery is mostly a continuous and complete coating. If the positive and negative electrode materials are coated too thickly, the electrolyte 500 will not be able to completely penetrate between the positive and negative electrode active materials, resulting in battery capacity loss. Therefore, the prior art mostly ensures the battery capacity by reducing the thickness of the active material coating and increasing the number of layers of battery cell winding or lamination. However, it is the active material on the positive and negative electrodes that actually provides energy inside the battery. As the number of layers increases, the number of separators 200 between the positive and negative electrodes also needs to be increased, and the proportion of the current collector 1 of the positive and negative electrodes increases. Therefore, under a certain battery volume, the proportion of active materials will be greatly reduced, which is not conducive to the improvement of battery energy density.

[0054] The pole piece 10 provided in the embodiment of the present application increases the contact area between the active material layer 2 and the electrolyte 500 by setting a wetting area 3 in at least one active material layer 2 and utilizing the gap between the wetting area 3 and the current collector 1 or the groove 31 of the wetting area 3, which is beneficial to increase the wetting speed of the electrolyte 500 and the wetting degree of the electrolyte 500 and the active material layer 2, thereby increasing the reaction activity of the active material and helping to improve the energy density of the battery.

[0055] In a specific embodiment, in at least one active material layer 2 , the length direction of the groove 31 is parallel to the width direction of the current collector 1 .

[0056] like Figure 1 As shown, the groove 31 extends along the width direction of the active material layer 2 , the extension length of the groove 31 is smaller than the width of the active material layer 2 , and both ends of the groove 31 do not penetrate the surface of the active material layer 2 .

[0057] Or, if Fig.11 As shown, the groove 31 extends along the width direction of the active material layer 2 , the extension length of the groove 31 is equal to the width of the active material layer 2 , and the groove 31 runs through two opposite surfaces of the active material layer 2 in the width direction.

[0058] In a further embodiment, there are a plurality of grooves 31 , and at least two adjacent grooves 31 have different extension lengths.

[0059] like Figure 6 As shown, a plurality of grooves 31 are distributed at intervals along the length direction of the current collector 1 , and the extension lengths of any two adjacent grooves 31 are different, presenting an alternating distribution pattern of long and short grooves.

[0060] This arrangement can improve the infiltration speed and degree of the electrolyte 500 and the active material while ensuring that the total amount of active material in the active material layer 2 is as large as possible, which helps to improve the battery capacity and energy density.

[0061] Exemplarily, the distance between any two adjacent grooves 31 is greater than 50 mm to prevent the current collector 1 from tearing and ensure the safety of the battery cell.

[0062] In an optional embodiment, there are multiple grooves 31, in one of the active material layers 2, such as Figure 1 As shown, the length direction of the groove 31 is parallel to the width direction of the current collector 1; in another active material layer 2, as shown Figure 7 As shown, the length direction of the groove 31 is parallel to the length direction of the current collector 1 .

[0063] In this embodiment, both active material layers 2 have a wetting region 3, and both wetting regions 3 include grooves 31, wherein the extension direction of at least one groove 31 in one active material layer 2 is perpendicular to the extension direction of at least one groove 31 in the other active material layer 2. Optionally, the grooves 31 in both active material layers 2 may be one or more.

[0064] In an optional embodiment, if Figure 8 As shown, both active material layers 2 have grooves 31 , and the grooves 31 in the two active material layers 2 are staggered in the length direction of the current collector 1 .

[0065] Exemplarily, both active material layers 2 have a wetting area 3, and the wetting area 3 includes a groove 31. In the orthographic projection of the electrode 10, the groove 31 in the first active material layer 2 and the groove 31 in the second active material layer 2 are parallel to each other and are spaced apart along the length direction of the current collector 1 to improve the wetting uniformity of the electrolyte 500 in the length direction of the current collector 1.

[0066] In another optional embodiment, Figure 2 and Figure 5 As shown, both active material layers 2 have grooves 31 , and the grooves 31 in the two active material layers 2 are symmetrically arranged along the thickness direction of the current collector 1 .

[0067] Exemplarily, both active material layers 2 have a wetting area 3, and the wetting area 3 includes a groove 31. In the orthographic projection of the electrode 10, the contour line of the groove 31 in the first active material layer 2 coincides with the contour line of the groove 31 in the second active material layer 2 to improve the wetting uniformity of the electrolyte 500 in the length direction of the current collector 1.

[0068] In one embodiment, the current collector 1 is provided with a first connection hole 12 , which penetrates the current collector 1 along the thickness direction of the current collector 1 , and the two active material layers 2 are connected through the first connection hole 12 to fill the first connection hole 12 .

[0069] like Fig. 9 As shown, a plurality of first connection holes 12 are opened in the current collector 1 , and two active material layers 2 are connected and filled in the first connection holes 12 .

[0070] In this embodiment, the first connection holes 12 are provided to allow the active materials on both sides of the current collector 1 to remain connected, which is beneficial to balancing the voltage on both sides of the current collector 1 and preventing uneven energy distribution on both sides of the current collector 1 in the thickness direction.

[0071] In one embodiment, the current collector 1 is provided with a second connection hole 13 , the second connection hole 13 penetrates the current collector 1 along the thickness direction of the current collector 1 , and the second connection hole 13 penetrates at least one active material layer 2 .

[0072] For example, Fig.10 As shown, the second connection hole 13 penetrates the current collector 1 and one of the active material layers 2 along the thickness direction of the current collector 1; or Fig.11 As shown, the second connection hole 13 penetrates the current collector 1 and the two active material layers 2 simultaneously along the thickness direction of the current collector 1 .

[0073] Through this arrangement, the current collector 1 and the active material layer 2 are opened together, which reduces the processing difficulty and ensures that the electrolyte 500 can fully infiltrate the active material.

[0074] In an optional embodiment, the groove 31 penetrates the active material layer 2 along the thickness direction of the current collector 1 , and there is a gap between the groove 31 and the edge of the active material layer 2 .

[0075] For example, Figure 1 and Figure 5 As shown, the groove 31 extends along the width direction of the current collector 1 , and the groove 31 penetrates the active material layer 2 along the thickness direction of the current collector 1 , but the groove 31 does not penetrate the active material layer 2 in the width direction and the length direction of the current collector 1 .

[0076] This arrangement ensures that the electrolyte 500 can fully penetrate into the active material while preventing the current collector 1 from tearing, which helps to ensure the safety of the battery cell.

[0077] In another optional embodiment, the depth of the groove 31 is less than the thickness of the active material layer 2 , and the groove 31 penetrates the active material layer 2 along its length direction.

[0078] For example, Figure 2 and Fig.12 As shown, the groove 31 extends along the width direction of the current collector 1 , and the groove 31 penetrates the active material layer 2 along the width direction of the current collector 1 , but the groove 31 does not penetrate the active material layer 2 in the thickness direction of the current collector 1 .

[0079] This configuration improves the infiltration speed and degree of the electrolyte 500 in the active material, which helps to improve the battery capacity and energy density.

[0080] In one embodiment, the current collector 1 has a folding region 11 , in which the current collector 1 is folded in a wave shape along its length direction, so that a gap 32 is generated between the surface of the wetted region 3 facing the current collector 1 and the current collector 1 .

[0081] like Fig.13 As shown, in the folding region 11, the current collector 1 is undulating and bent in a wave-like manner, and the cross-sectional shape of the bend can be a triangle, an ellipse, etc. The folding region 11 can be formed by an embossing process, etc. The active material layer 2 is located on both sides of the current collector 1 in the thickness direction and has a gap 32 with the current collector 1, so that the electrolyte 500 flows in the gap 32.

[0082] In this embodiment, by setting the current collector 1 in the folding area 11 to be in a continuously folded form, a gap 32 is generated between the active material and the current collector 1, which helps the electrolyte 500 to fully infiltrate the active material, improves the reaction activity of the active material, and is beneficial to improving the energy density of the battery.

[0083] like Fig.14 and Fig.15 As shown, an embodiment of the present application also provides a battery cell, including a shell 100, a diaphragm 200, a positive electrode sheet 300 and a negative electrode sheet 400, the diaphragm 200, the positive electrode sheet 300 and the negative electrode sheet 400 are accommodated in the shell 100, the diaphragm 200 is arranged between the positive electrode sheet 300 and the negative electrode sheet 400, and the positive electrode sheet 300 and / or the negative electrode sheet 400 are the sheets 10 provided in any of the above embodiments.

[0084] Among them, the positive electrode sheet 300 and the negative electrode sheet 400 are both provided with a tab 600, and the structures of the positive electrode sheet 300 and the negative electrode sheet 400 can be the same or different; Fig.14 As shown, the positive electrode sheet 300 and the negative electrode sheet 400 can both be the electrode sheet 10 provided in the embodiment of the present application; Fig.15 As shown, only one of them may be the pole piece 10 provided in the embodiment of the present application.

[0085] The battery cell provided in the embodiment of the present application increases the contact area between the active material layer 2 and the electrolyte 500 by setting a wetting area 3 in at least one active material layer 2 and utilizing the gap between the wetting area 3 and the current collector 1 or the groove 31 of the wetting area 3, which is beneficial to increase the wetting speed of the electrolyte 500 and the wetting degree of the electrolyte 500 and the active material layer 2, thereby increasing the reaction activity of the active material and helping to improve the energy density of the battery.

[0086] In the present application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0087] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the present application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only.

[0088] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A pole piece (10), characterized in that: The pole piece (10) comprises a current collector (1) and two active material layers (2), wherein the two active material layers (2) are respectively arranged on both sides of the current collector (1) in a thickness direction, and at least one of the active material layers (2) has a wetting area (3); A gap (32) is provided between the surface of the wetting region (3) facing the current collector (1) and the current collector (1), and / or a groove (31) is provided on the surface of the wetting region (3) facing away from the current collector (1), wherein the gap (32) penetrates at least one surface of the active material layer (2) along its extension direction.

2. The pole piece (10) according to claim 1, characterized in that: In at least one of the active material layers (2), the length direction of the groove (31) is parallel to the width direction of the current collector (1).

3. The pole piece (10) according to claim 2, characterized in that: There are a plurality of grooves (31), and at least two adjacent grooves (31) have different extension lengths.

4. The pole piece (10) according to claim 2, characterized in that: There are a plurality of grooves (31), and in one of the active material layers (2), the length direction of the grooves (31) is parallel to the width direction of the current collector (1); and in another active material layer (2), the length direction of the grooves (31) is parallel to the length direction of the current collector (1).

5. The pole piece (10) according to any one of claims 2 to 4, characterized in that: The two active material layers (2) both have the grooves (31), and the grooves (31) in the two active material layers (2) are staggeredly distributed in the length direction of the current collector (1).

6. The pole piece (10) according to any one of claims 2 to 4, characterized in that: The two active material layers (2) both have the groove (31), and the grooves (31) in the two active material layers (2) are symmetrically arranged along the thickness direction of the current collector (1).

7. The pole piece (10) according to claim 1, characterized in that: The current collector (1) is provided with a first connection hole (12), the first connection hole (12) penetrates the current collector (1) along the thickness direction of the current collector (1), and the two active material layers (2) are connected through the first connection hole (12) to fill the first connection hole (12).

8. The pole piece (10) according to claim 1, characterized in that: The current collector (1) is provided with a second connection hole (13), the second connection hole (13) penetrates the current collector (1) along the thickness direction of the current collector (1), and the second connection hole (13) penetrates at least one of the active material layers (2).

9. The pole piece (10) according to claim 1, characterized in that: The groove (31) penetrates the active material layer (2) along the thickness direction of the current collector (1), and there is a gap between the groove (31) and the edge of the active material layer (2).

10. The pole piece (10) according to claim 1, characterized in that: The depth of the groove (31) is less than the thickness of the active material layer (2) in which it is located, and the groove (31) penetrates the active material layer (2) in its length direction.

11. The pole piece (10) according to claim 1, characterized in that: The current collector (1) has a folding region (11), in which the current collector (1) is folded in a wave-like shape along its length direction, so that the gap (32) is generated between the surface of the wetted region (3) facing one side of the current collector (1) and the current collector (1).

12. A battery cell, characterized in that: The battery cell comprises a shell (100), a diaphragm (200), a positive electrode sheet (300) and a negative electrode sheet (400); the diaphragm (200), the positive electrode sheet (300) and the negative electrode sheet (400) are accommodated in the shell (100); the diaphragm (200) is arranged between the positive electrode sheet (300) and the negative electrode sheet (400); the positive electrode sheet (300) and / or the negative electrode sheet (400) are the electrode sheets (10) according to any one of claims 1 to 11.

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