Pole piece and battery

Abstract

The utility model discloses a pole piece which is suitable for winding a battery cell and comprises a current collector. The current collector comprises a plurality of first empty foil areas and a plurality of coating areas, active material layers are arranged on the coating areas, the first direction is set as the length direction of the current collector, and the first empty foil areas are arranged among the coating areas in the first direction. Wherein the second direction is set as the width direction of the current collector, along the second direction, each coating area comprises a first side edge and a second side edge which are oppositely arranged, along the second direction, each first empty foil area comprises a third side edge and a fourth side edge which are oppositely arranged, and along the second direction, each third side edge is arranged between each first side edge and each second side edge. When the current collector is wound, the third side edge is arranged at the corner of the wound battery cell, and the wound battery cell is not easy to cause expansion damage when the current collector is heated to expand, so that a gap between the wound battery cell and a battery shell is reduced, and the energy density of the wound battery cell is improved.

Description

Technical Field

[0001] The present application relates to the field of battery design, production and manufacturing, and in particular to a pole piece and a battery. Background Art

[0002] In modern society, the use and storage of energy are developing rapidly, especially electrochemical energy storage. A battery is a battery composed of multiple electrochemical units, each of which is composed of an anode electrode, a cathode electrode and a separator, which are wound together to form a whole. Its basic working principle is to convert the electron flow in the chemical reaction into electric current, and complete the conversion of electric current through the conduction of electrolytes.

[0003] In the prior art, in order to ensure the adaptability and effect of the package, it is usually necessary to leave a certain space between the battery case and the battery core. This results in the space utilization of the battery case being limited. In order to increase the energy density of the battery, a gap between the battery case and the battery core is required, but this will cause the battery core to expand due to heat and break the battery case when the battery is in working condition, causing the battery to fail. In particular, since the force area at the corner of the battery core is smaller than the main body of the battery core, when the battery core expands, the corner is prone to damage. Therefore, in the prior art, in order to reduce the damage to the battery caused by the thermal expansion of the corner of the battery core, the gap between the battery case and the battery core is larger, which reduces the energy density of the battery. Utility Model Content

[0004] The main purpose of this application is to propose a pole piece and a battery, which aims to solve the technical problem that the gap between the battery shell and the battery core is large in order to reduce the thermal expansion of the corners of the battery core and cause battery damage, thereby reducing the energy density of the battery.

[0005] In order to solve the above problems, the present application proposes a pole piece, which is suitable for winding a battery cell, and the pole piece includes:

[0006] A current collector, the current collector comprising a plurality of first empty foil areas and a plurality of coating areas, an active material layer is provided on the coating area, a first direction is set as a length direction of the current collector, and along the first direction, each of the first empty foil areas is provided between the coating areas;

[0007] Among them, the second direction is set to the width direction of the current collector, along the second direction, each of the coating areas includes a first side and a second side arranged opposite to each other, along the second direction, each of the first empty foil areas includes a third side and a fourth side arranged opposite to each other, along the second direction, each of the third sides is arranged between each of the first sides and each of the second sides.

[0008] In some embodiments, along the second direction, the distance from the first side to the third side is less than the distance from the second side to the third side, and the distance from the first side to the third side is D1, and the distance D1 satisfies: 0.1mm≤D1≤0.2mm.

[0009] In some embodiments, along the second direction, the fourth side is disposed between the first side and the second side.

[0010] In some embodiments, along the second direction, the distance from the first side to the fourth side is greater than the distance from the second side to the fourth side, the distance from the second side to the fourth side is D2, and the distance D2 satisfies: 0.1mm≤D2≤0.2mm.

[0011] In some embodiments, along the first direction, each of the first empty foil areas includes a fifth side and a sixth side arranged at intervals, the distance from the fifth side to the sixth side is D3, the distance from the first side to the second side is D4, the third direction is the thickness direction of the current collector, the first projection plane is set to be a plane perpendicular to the third direction, each of the first empty foil areas forms a first orthographic projection on the first projection plane, the area of ​​the first orthographic projection is S1, the distance D1, the distance D3, the distance D4 and the area S1 satisfy: D3D4-D1D3 <S1<D3D4-0.5×D1D3。

[0012] In some embodiments, the distance D1, the distance D3, the distance D4 and the area S1 satisfy: D3D4-0.875×D1D3≤S1≤D3D4-0.625×D1D3.

[0013] In some embodiments, the current collector includes two second empty foil areas arranged opposite to each other along the first direction, the first empty foil area and the coating area are arranged between the second empty foil areas, the pole piece includes a pole ear, the pole ear is connected to the second empty foil area, and the pole ear is arranged on a side close to the first side edge;

[0014] or,

[0015] The current collector includes two second empty foil areas arranged opposite to each other along the first direction, the first empty foil area and the coating area are arranged between the second empty foil areas, and the pole piece includes a pole ear connected to the second empty foil area, and the pole ear is arranged on a side close to the second side edge.

[0016] In some embodiments, along the second direction, each of the second empty foil areas includes a seventh side and an eighth side that are oppositely disposed, the first side is parallel to the seventh side, and the second side is parallel to the eighth side.

[0017] The second aspect of the present application also provides a battery, comprising:

[0018] The pole pieces described in any one of the two above-mentioned embodiments, each pole piece has a different polarity;

[0019] A battery housing, the battery housing being used to hold each of the pole pieces;

[0020] Among them, the two pole pieces are wound to form the wound battery cell, and the wound battery cell includes a bending area and a straight area. The first empty foil area of ​​each pole piece is arranged in the bending area, and the second side edge of each pole piece is abutted against the battery shell.

[0021] In some embodiments, each of the pole pieces includes the second empty foil area, and each of the second empty foil areas is arranged in the straight area.

[0022] Compared with the prior art, the beneficial effects of this application are:

[0023] In the technical solution of the present application, the current collector includes a plurality of first empty foil areas and a plurality of coating areas, an active material layer is provided on the coating area, the first direction is set as the length direction of the current collector, along the first direction, each first empty foil area is arranged between the coating areas, the second direction is set as the width direction of the current collector, along the second direction, each coating area includes a first side edge and a second side edge arranged relatively, along the second direction, each first empty foil area includes a third side edge and a fourth side edge arranged relatively, along the second direction, each third side edge is arranged between each first side edge and each second side edge. By arranging the third side edge between each first side edge and each second side edge, so that when the current collector is wound, the third side edge is arranged at the corner of the wound battery cell, reducing the shortest distance from the corner of the wound battery cell to the battery housing, so that when the wound battery cell expands due to heat, the wound battery cell is not easily damaged by expansion, so that the gap between the wound battery cell and the battery housing can be reduced, thereby improving the energy density of the wound battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application 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 present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 It is a side view schematic diagram of the first type of pole piece in the embodiment of the present application; wherein D1, D2, D3 and D4 are shown in the figure;

[0026] Figure 2 It is a side view schematic diagram of the second type of electrode in the embodiment of the present application; wherein the current collector includes a third side;

[0027] Figure 3 It is a side view schematic diagram of the second type of pole piece in the embodiment of the present application;

[0028] Figure 4 It is a side view schematic diagram of a pole piece in the third embodiment of the present application; wherein the pole piece includes a pole ear;

[0029] Figure 5 A schematic side view of a pole piece from a first viewing angle in a fourth embodiment of the present application;

[0030] Figure 6 It is a side view schematic diagram of the pole piece in the fourth embodiment of the present application from a second viewing angle; wherein the figure shows a third direction;

[0031] Figure 7 A schematic side view of a battery from a first viewing angle in the first embodiment of the present application;

[0032] Figure 8 This is a schematic side view of the battery in the first embodiment of the present application from a second viewing angle; wherein the figure shows a bending area and a straight area.

[0033] Description of Figure Numbers:

[0034] Pole piece 10;

[0035] Current collector 100;

[0036] A first empty foil area 110;

[0037] A third side 111;

[0038] a fourth side 112;

[0039] a fifth side 113;

[0040] a sixth side 114;

[0041] coating area 120;

[0042] A first side edge 121;

[0043] A second side edge 122;

[0044] Active material layer 123;

[0045] A second empty foil area 130;

[0046] seventh side 131;

[0047] eighth side 132;

[0048] Tab 200;

[0049] Winding the battery cell 20;

[0050] Battery 30;

[0051] Battery housing 40;

[0052] Bending zone 50;

[0053] Straight area 60;

[0054] First direction X;

[0055] The second direction Y;

[0056] The third direction Z.

[0057] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0058] 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 embodiment is only a component embodiment of the present application, rather than an embodiment of the entire component. 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.

[0059] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0060] In addition, when an element is said to be "fixed to" another element, it can be directly on the other element, or one or more intervening elements can exist between them. When an element is said to be "connected to" another element, it can be directly connected to the other element, or one or more intervening elements can exist between them.

[0061] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or", "and / or" or "and / or" appears in the full text, its meaning includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0062] In the prior art, in order to ensure the adaptability and effect of the package, it is usually necessary to leave a certain space between the battery case and the battery core. This results in the space utilization of the battery case being limited. In order to increase the energy density of the battery, a gap between the battery case and the battery core is required, but this will cause the battery core to expand due to heat and break the battery case when the battery is in working condition, causing the battery to fail. In particular, since the force area at the corner of the battery core is smaller than the main body of the battery core, when the battery core expands, the corner is prone to damage. Therefore, in the prior art, in order to reduce the damage to the battery caused by the thermal expansion of the corner of the battery core, the gap between the battery case and the battery core is larger, which reduces the energy density of the battery.

[0063] In order to solve the above problems, the present application proposes a pole piece 10, see Figures 1 to 6 The pole piece 10 is suitable for winding the battery cell 20, and the pole piece 10 includes a current collector 100. It should be noted that the polarity of the pole piece 10 can be a cathode or an anode.

[0064] The current collector 100 includes a plurality of first empty foil areas 110 and a plurality of coating areas 120. For example, the number of the first empty foil areas 110 may be two, three, four, five, or six, and the number of the coating areas 120 may be two, three, four, five, or six. An active material layer 123 is provided on the coating area 120. It should be noted that the active material layer 123 is a main component of the positive and negative electrodes of the battery 30, which contains active materials capable of electrochemical reactions. The first empty foil area 110 does not include the active material layer 123 in at least part. The first direction X is set as the length direction of the current collector 100. Along the first direction X, each first empty foil area 110 is provided between each coating area 120, that is, each first empty foil area 110 is provided between at least two coating areas 120. The outer contours of each current collector 100 may be the same or different. This application takes the same outer contour as an example. The outer contour of the current collector 100 may be in a variety of structures. In some embodiments, the current collector 100 may be a rectangular parallelepiped. In other embodiments, the current collector 100 may be cylindrical. In other embodiments, the current collector 100 may be a polygon, etc., depending on the actual situation. The embodiment of the present application takes the rectangular current collector 100 as an example. The outer contours of each first empty foil area 110 may be the same or different. The present application takes the same outer contour as an example. The outer contour of the first empty foil area 110 may be in a variety of structures. In some embodiments, the first empty foil area 110 may be a rectangular parallelepiped. In other embodiments, the first empty foil area 110 may be a cylinder. In other embodiments, the first empty foil area 110 may be a polygon, etc., depending on the actual situation. The embodiment of the present application takes the rectangular first empty foil area 110 as an example. The outer contours of each coating area 120 may be the same or different. The present application takes the same outer contour as an example. The outer contour of the coating area 120 may be in a variety of structures. In some embodiments, the coating area 120 may be a rectangular parallelepiped. In other embodiments, the coating area 120 may be a cylinder. In other embodiments, the coating area 120 may be a polygon, etc., depending on the actual situation. The embodiment of the present application takes a rectangular coating area 120 as an example.

[0065] The second direction Y is set as the width direction of the current collector 100. Along the second direction Y, each coating area 120 includes a first side 121 and a second side 122 arranged oppositely. The first sides 121 are parallel to each other and are on the same plane. The second sides 122 are parallel to each other and are on the same plane. In some embodiments, the first side 121 and the second side 122 are parallel. Along the second direction Y, each first empty foil area 110 includes a third side 111 and a fourth side 112 arranged oppositely. The third sides 111 are parallel to each other and are on the same plane. The fourth sides 112 are parallel to each other and are on the same plane. In some embodiments, the third side 111 and the fourth side 112 are parallel to each other. Along the second direction Y, each third side 111 is arranged between each first side 121 and each second side 122, that is, along the second direction Y, the distance D1 from the first side 121 to the third side 111, the distance D4 from the first side 121 to the second side 122, and the distance D5 from the second side 122 to the third side 111, the distance D1, the distance D4 and the distance D5 satisfy: D1+D5=D4. By arranging the third side 111 between each first side 121 and each second side 122, when the current collector 100 is wound, the third side 111 is arranged at the corner of the wound battery cell 20, reducing the shortest distance from the corner of the wound battery cell 20 to the battery case 40, so that when the wound battery cell 20 expands due to heat, the wound battery cell 20 is not easily damaged by expansion, so that the gap between the wound battery cell 20 and the battery case 40 can be reduced, and the energy density of the wound battery cell 20 is improved. In some embodiments, the first empty foil area 110 is formed by cutting the electrode sheet 10, so that each third side 111 is arranged between each first side 121 and each second side 122. In other embodiments, the first empty foil area 110 is formed by cutting the wound battery cell 20 after winding, so that each third side 111 is arranged between each first side 121 and each second side 122. It should be noted that the above methods can achieve the effect of reducing the shortest distance from the corner of the wound battery cell 20 to the battery housing 40, so that when the wound battery cell 20 expands due to heat, the wound battery cell 20 is not easily damaged by expansion.

[0066] See also Figure 1, along the second direction Y, the distance from the first side 121 to the third side 111 is less than the distance from the second side 122 to the third side 111, the distance from the first side 121 to the third side 111 is D1, and the distance D1 satisfies: 0.1mm≤D1≤0.2mm, and illustratively, the distance D1 can be 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.2mm, etc. It should be noted that the distance D1 should be moderate. When the distance D1 is large, the connection stability of the first empty foil area 110 and the coating area 120 is poor, resulting in the easy damage of the wound battery cell 20; when the distance D1 is small, the corners of the wound battery cell 20 are sharp, resulting in the easy expansion damage of the wound battery cell 20. Therefore, when the distance D1 is of a moderate value, the stability of the wound battery cell 20 is relatively high.

[0067] In some embodiments, see Figure 1 , along the second direction Y, the fourth side 112 is arranged between the first side 121 and the second side 122, that is, along the second direction Y, the distance D6 from the first side 121 to the fourth side 112, the distance D4 from the first side 121 to the second side 122, and the distance D2 from the second side 122 to the fourth side 112, the distance D2, the distance D4 and the distance D6 satisfy: D2+D6=D4. By arranging the fourth side 112 between each first side 121 and each second side 122, when the current collector 100 is wound, the fourth side 112 is arranged at the corner of the wound battery cell 20, thereby reducing the shortest distance from the corner of the wound battery cell 20 to the battery case 40, so that when the wound battery cell 20 expands due to heat, the wound battery cell 20 is not easily damaged by expansion, so that the gap between the wound battery cell 20 and the battery case 40 can be reduced, thereby improving the energy density of the wound battery cell 20.

[0068] For further information, see Figure 1, along the second direction Y, the distance from the first side 121 to the fourth side 112 is greater than the distance from the second side 122 to the fourth side 112. The distance from the second side 122 to the fourth side 112 is D2, and the distance D2 satisfies: 0.1 mm ≤ D2 ≤ 0.2 mm. Exemplarily, the distance D2 can be 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, etc. It should be noted that the distance D2 should be appropriate. When the distance D2 is large, the connection stability between the first empty foil area 110 and the coating area 120 is poor, resulting in easy damage to the wound battery cell 20. When the distance D2 is small, the corners of the wound battery cell 20 are relatively sharp, resulting in easy expansion damage to the wound battery cell 20. Therefore, when the value of the distance D2 is appropriate, the stability of the wound battery cell 20 is relatively high.

[0069] Along the first direction X, referring to Figure 1 , each first empty foil area 110 includes a fifth side 113 and a sixth side 114 arranged at intervals. The distance from the fifth side 113 to the sixth side 114 is D3, and the distance from the first side 121 to the second side 122 is D4. The third direction is the thickness direction of the current collector 100, and the first projection plane is set as a plane perpendicular to the third direction. Each first empty foil area 110 forms a first orthographic projection on the first projection plane, and the area of the first orthographic projection is S1. The distance D1, the distance D3, the distance D4, and the area S1 satisfy: D3D4 - D1D3 < S1 < D3D4 - 0.5×D1D3. Exemplarily, the area S1 can take values such as D3D4 - 0.9D1D3, D3D4 - 0.8D1D3, D3D4 - 0.7D1D3, D3D4 - 0.6D1D3, etc. It should be noted that two removal areas are defined between the first empty foil area 110 and the two adjacent coating areas 120. Each removal area forms a second orthographic projection on the first projection plane, and the area of the second orthographic projection is S2. The area S2 satisfies: 0.5×D1D3 < S2 < D1D3. Exemplarily, 0.6D1D3, 0.7D1D3, 0.8D1D3, 0.9D1D3, etc. It should be noted that the distance S2 should be appropriate. When the distance S2 is large, the connection stability between the first empty foil area 110 and the coating area 120 is poor. When the distance S2 is small, the corners of the wound battery cell 20 are relatively sharp. Therefore, when the value of the distance S2 is appropriate, the stability of the wound battery cell 20 is relatively high.

[0070] In some embodiments, referring to Figure 1, the distance D1, the distance D3, the distance D4, and the area S1 satisfy: D3D4 - 0.875×D1D3 ≤ S1 ≤ D3D4 - 0.625×D1D3. Exemplarily, D3D4 - 0.875×D1D3, D4D4 - 0.825×D1D3, D4D4 - 0.775×D1D3, D3D4 - 0.725×D1D3, D3D4 - 0.675×D1D3, D3D4 - 0.625×D1D3, and so on. It can be understood that the area S2 satisfies: 0.625×D1D3 < S2 < 0.875×D1D3. Exemplarily, 0.65D1D3, 0.70D1D3, 0.75D1D3, 0.8D1D3, 0.85D1D3, and so on.

[0071] In some embodiments, referring to Figure 4 , the current collector 100 includes two second empty foil regions 130 arranged oppositely along the first direction X. The outer contour of each second empty foil region 130 may be the same or different. In this application, different outer contours are taken as an example. The outer contour of the second empty foil region 130 may have various structures. In some embodiments, the second empty foil region 130 may be in the shape of a cuboid. In some other embodiments, the second empty foil region 130 may be in the shape of a cylinder. In other embodiments, the second empty foil region 130 may be in the shape of a polyhedron, etc., depending on the actual situation. In the embodiments of this application, the cuboid second empty foil region 130 is taken as an example. The first empty foil region 110 and the coating region 120 are arranged between the second empty foil regions 130. The electrode tab 10 includes a tab 200, and the tab 200 is connected to the second empty foil region 130. In some embodiments, the tab 200 is arranged on one side close to the first side 121. In some other embodiments, the tab 200 is arranged on one side close to the second side 122.

[0072] Along the second direction Y, referring to Figure 4 , each second empty foil region 130 includes a seventh side 131 and an eighth side 132 arranged oppositely. The seventh sides 131 are parallel to each other and are in the same plane. The eighth sides 132 are parallel to each other and are in the same plane. The first side 121 is parallel to the seventh side 131, and the second side 122 is parallel to the eighth side 132. In some embodiments, the first side 121 and the seventh side 131 are in the same plane. In some embodiments, the second side 122 and the eighth side 132 are in the same plane.

[0073] The second aspect of this application further provides a battery 30, referring to Figure 7 and Figure 8 , the battery 30 includes two electrode tabs 10 with different polarities in any of the above embodiments and a battery housing 40.

[0074] The battery case 40 is used to hold each pole piece 10 . The battery case 40 is configured to abut against the wound battery cell 20 when the wound battery cell 20 expands due to heat, so as to prevent the wound battery cell 20 from being damaged.

[0075] Among them, two pole pieces 10 are wound to form a battery 30, and the battery 30 includes a bending area 50 and a straight area 60. It should be noted that the bending area 50 is the area where the pole piece 10 is bent, and the straight area 60 is the area where the pole piece 10 is straight. The first empty foil area 110 of each pole piece 10 is arranged in the bending area 50, so that the third side 111 is arranged at the corner of the wound battery cell 20, reducing the shortest distance from the corner of the wound battery cell 20 to the battery housing 40, so that when the wound battery cell 20 expands due to heat, the wound battery cell 20 is not easy to cause expansion damage, so that the gap between the wound battery cell 20 and the battery housing 40 can be reduced, thereby improving the energy density of the wound battery cell 20. The second side 122 of each pole piece 10 is in contact with the battery housing 40.

[0076] In some embodiments, each pole piece 10 includes a second empty foil area 130, and each second empty foil area 130 is disposed in the straight area 60. By disposing each second empty foil area 130 in the straight area 60, the second empty foil area 130 is avoided from being disposed in the bending area 50, thereby reducing the shortest distance from the corner of the wound battery cell 20 to the battery housing 40.

[0077] It should be noted that other contents of the battery 30, the tab 200 and the battery 30 casing disclosed in the present application can be referred to the prior art and will not be described in detail here.

[0078] In addition, it should be noted that the preferred embodiments of the present application are given in the specification and drawings of the present application, but the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional restrictions on the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Moreover, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the present application; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present application.

Claims

1. A pole piece, characterized in that: The pole piece is suitable for winding a battery cell, and the pole piece comprises: A current collector, the current collector comprising a plurality of first empty foil areas and a plurality of coating areas, an active material layer is provided on the coating area, a first direction is set as a length direction of the current collector, and along the first direction, each of the first empty foil areas is provided between each of the coating areas; Among them, the second direction is set to the width direction of the current collector, along the second direction, each of the coating areas includes a first side and a second side arranged opposite to each other, along the second direction, each of the first empty foil areas includes a third side and a fourth side arranged opposite to each other, along the second direction, each of the third sides is arranged between each of the first sides and each of the second sides.

2. The pole piece according to claim 1, characterized in that: Along the second direction, the distance from the first side to the third side is smaller than the distance from the second side to the third side, and the distance from the first side to the third side is D1, and the distance D1 satisfies: 0.1 mm≤D1≤0.2 mm.

3. The pole piece according to claim 1, characterized in that: Along the second direction, the fourth side is disposed between the first side and the second side.

4. The pole piece according to claim 3, characterized in that: Along the second direction, the distance from the first side to the fourth side is greater than the distance from the second side to the fourth side, the distance from the second side to the fourth side is D2, and the distance D2 satisfies: 0.1 mm≤D2≤0.2 mm.

5. The pole piece according to claim 1, characterized in that: Along the first direction, each of the first empty foil areas includes a fifth side and a sixth side arranged at intervals, the distance from the fifth side to the sixth side is D3, the distance from the first side to the second side is D4, the third direction is the thickness direction of the current collector, the first projection plane is set to be a plane perpendicular to the third direction, each of the first empty foil areas forms a first orthographic projection on the first projection plane, the area of ​​the first orthographic projection is S1, the distance D1, the distance D3, the distance D4 and the area S1 satisfy: D3D4-D1D3 <S1<D3D4-0.5×D1D3。 6. The pole piece according to claim 5, characterized in that: The distance D1, the distance D3, the distance D4 and the area S1 satisfy: D3D4-0.875×D1D3≤S1≤D3D4-0.625×D1D4.

7. The pole piece according to claim 1, characterized in that: The current collector includes two second empty foil areas arranged opposite to each other along the first direction, the first empty foil area and the coating area are arranged between the second empty foil areas, the pole piece includes a pole ear, the pole ear is connected to the second empty foil area, and the pole ear is arranged on a side close to the first side edge; or, The current collector includes two second empty foil areas arranged opposite to each other along the first direction, the first empty foil area and the coating area are arranged between the second empty foil areas, and the pole piece includes a pole ear connected to the second empty foil area, and the pole ear is arranged on a side close to the second side edge.

8. The pole piece according to claim 7, characterized in that: Along the second direction, each of the second empty foil areas includes a seventh side and an eighth side that are oppositely arranged, the first side is parallel to the seventh side, and the second side is parallel to the eighth side.

9. A battery, characterized in that: include: The pole pieces according to any one of claims 1 to 8, wherein the polarities of the pole pieces are different; A battery housing, the battery housing being used to hold each of the pole pieces; Among them, the two pole pieces are wound to form the wound battery cell, and the wound battery cell includes a bending area and a straight area. The first empty foil area of ​​each pole piece is arranged in the bending area, and the second side edge of each pole piece is abutted against the battery shell.

10. The battery according to claim 9, characterized in that Each of the pole pieces includes the second empty foil area, Each of the second empty foil areas is arranged in the flat area.

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