Pole piece and battery cell

Abstract

The utility model discloses a pole piece and a battery cell, the pole piece is used for a winding type battery cell, and the pole piece comprises a current collector and a colloid part. The current collector comprises a first empty foil area and a coating area, an active material layer is arranged on the coating area, and a first through hole is formed in the first empty foil area in the thickness direction of the current collector. And the colloid part is arranged in the first through hole. The current collector comprises an inner end part and an outer end part along the length direction of the current collector, the first empty foil area is arranged at the outer end part, and when the current collector is in a winding state, the inner end part is arranged at the inner ring of the current collector, and the outer end part is arranged at the outer ring of the current collector. According to the battery, the first empty foil area is arranged at the outer end part, and the first empty foil area comprises the colloid part, so that under the conditions that the thickness of the battery is not increased and the energy density of the battery is not changed, a connecting force is provided through the colloid part, and the coiled battery core is connected.

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 cell. Background Art

[0002] Soft-pack square battery cells are increasingly being used in the 3C electronics field, and roller tests and drop tests for application reliability and safety are becoming increasingly important within the industry. Existing technologies either add double-sided hot-melt adhesive tape to the surface of the reel of soft-pack square battery cells or directly use double-sided hot-melt adhesive tape to secure the bare cells. This increases the connection between the reel and the aluminum-plastic film, limiting the movement of the bare cells within the aluminum-plastic film during roller or drop tests. The main disadvantage of this method is that adding hot-melt adhesive tape to the surface of the bare cells increases the thickness of the cells, resulting in a decrease in the energy density of the cells. Utility Model Content

[0003] The main purpose of this application is to propose a pole piece and a battery cell, which aims to solve the technical problem of using double-sided hot melt adhesive tape to connect the pole piece and the battery cell to provide connecting force for connecting the bare battery cell, but resulting in an increase in the thickness of the battery, a decrease in the energy density of the battery, and a decrease in the working efficiency of the battery.

[0004] To achieve the above objectives, the present application proposes a pole piece for a wound battery cell, comprising:

[0005] A current collector, comprising a first hollow foil region and a coating region, wherein an active material layer is provided on the coating region, and along a thickness direction of the current collector, the first hollow foil region is provided with a first through hole;

[0006] a colloid portion, the colloid portion being disposed in the first through hole;

[0007] Among them, along the length direction of the current collector, the current collector includes an inner end and an outer end, the first empty foil area is arranged at the outer end, and when the current collector is in a wound state, the inner end is arranged at the inner circle of the current collector, and the outer end is arranged at the outer circle of the current collector.

[0008] In some embodiments, the first projection plane is set to a plane perpendicular to the thickness direction of the current collector, the first empty foil area forms a first orthographic projection on the first projection plane, and the area of ​​the first orthographic projection is set to The colloid portion forms a second orthographic projection on the first projection plane, and the area of ​​the second orthographic projection is set to , the area and the area satisfy: .

[0009] In some embodiments, the area and the area satisfy: .

[0010] In some embodiments, there are a plurality of the first through holes, and in the first empty foil area, the first through holes are arranged at intervals.

[0011] In some embodiments, when the current collector is in a wound state, the pole piece is suitable for being wound with another pole piece having a different polarity to form the battery core, and the outer end portion is suitable for being arranged outside the other pole piece.

[0012] In some embodiments, the pole piece includes a pole ear portion, the current collector includes a second empty foil area, the pole ear portion is connected to the second empty foil area, and the second empty foil area is provided at the inner end portion.

[0013] In some embodiments, the second projection plane is set to a plane perpendicular to the width direction of the current collector, the first empty foil area forms a third orthographic projection on the second projection plane, and the area of ​​the third orthographic projection is set to The colloid portion forms a fourth orthographic projection on the second projection plane, and the area of ​​the fourth orthographic projection is set to , the area and the area satisfy: .

[0014] In some embodiments, the third projection plane is set to a plane perpendicular to the length direction of the current collector, the first empty foil area forms a fifth orthographic projection on the third projection plane, and the area of ​​the fifth orthographic projection is set to The colloid portion forms a sixth orthographic projection on the third projection plane, and the area of ​​the sixth orthographic projection is set to , the area and the area satisfy: .

[0015] In a second aspect of the present application, a battery cell is provided. The battery cell is a wound type battery cell and includes:

[0016] The pole piece described in any one of the above embodiments;

[0017] A battery cell casing, wherein the battery cell casing is used to load the electrode piece.

[0018] In some embodiments, the polarity of the electrode piece is an anode, and the battery cell further includes a cathode electrode piece. When the current collector is in a wound state, the electrode piece is suitable for being wound with the cathode electrode piece, and the outer end portion is suitable for being arranged outside the cathode electrode piece.

[0019] Alternatively, the polarity of the electrode sheet is cathode, and the battery cell further includes an anode electrode sheet. When the current collector is in a wound state, the electrode sheet is suitable for being wound with the anode electrode sheet, and the outer end portion is suitable for being arranged outside the anode electrode sheet.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] In the technical solution of the present application, a pole piece is used for a wound battery cell, and the pole piece includes a current collector and a colloid portion. The current collector includes a first empty foil area and a coating area, and an active material layer is provided on the coating area. Along the thickness direction of the current collector, the first empty foil area is provided with a first through hole, and the colloid portion is provided in the first through hole. Along the length direction of the current collector, the current collector includes an inner end and an outer end, and the first empty foil area is provided at the outer end. When the current collector is in a wound state, the inner end is provided at the inner ring of the current collector, and the outer end is provided at the outer ring of the current collector. By providing the first empty foil area at the outer end, and the first empty foil area including the colloid portion, the winding battery cell can be connected by providing a connecting force through the colloid portion without increasing the thickness of the battery and ensuring that the energy density of the battery remains unchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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.

[0023] Figure 1 Schematic side view of the first type of electrode sheet in the embodiment of the present application; wherein the line of sight in the schematic view is along a direction perpendicular to the thickness of the current collector, the electrode sheet includes an electrode ear portion, the current collector includes a second hollow foil region, and the number of first through holes is multiple, and each first through hole forms a rectangular array along a plane;

[0024] Figure 2 Schematic side view of the first type of electrode in the embodiment of the present application; wherein the line of sight in the schematic is along a direction perpendicular to the width of the current collector, the electrode includes an electrode ear portion, the current collector includes a second hollow foil area, and the active material layer is shown in the figure;

[0025] Figure 3 Schematic side view of the second type of electrode piece in the embodiment of the present application; wherein the line of sight in the schematic view is along a direction perpendicular to the thickness of the current collector, the electrode piece includes a pole ear portion, the current collector includes a second hollow foil area, and the number of the first through hole is one;

[0026] Figure 4Schematic side view of the first cathode electrode sheet according to an embodiment of the present application; wherein the line of sight in the schematic view is along a direction perpendicular to the thickness of the current collector, the cathode electrode sheet includes an ear portion, the current collector includes a second hollow foil region, and the number of first through holes is multiple, each of the first through holes forming a rectangular array along a plane;

[0027] Figure 5 This is a cross-sectional schematic diagram of the first type of battery cell in the embodiment of the present application, wherein the current collector is wound and the figure shows the contact manner between the colloid portion and the other electrode sheet;

[0028] Figure 6 This is a side view of the first type of battery cell in the embodiment of the present application; wherein a pole piece and another pole piece with a different polarity are wound to form the battery cell;

[0029] Figure 7 This is a side view schematic diagram of the first type of battery cell in the embodiment of the present application; wherein, a pole piece and another pole piece with a different polarity are wound to form a battery cell, and the pole piece includes an inner end and an outer end, the inner end is arranged on the inner ring of the collector, and the outer end is arranged on the outer ring of the collector.

[0030] Description of Figure Numbers:

[0031] Pole piece 10;

[0032] Current collector 100;

[0033] a first empty foil area 110;

[0034] a first through hole 111;

[0035] coating area 120;

[0036] inner end portion 130;

[0037] outer end portion 140;

[0038] a second empty foil area 150;

[0039] colloid part 200;

[0040] Pole ear 300;

[0041] Battery cell 20;

[0042] Battery cell housing 30.

[0043] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiment described is only an embodiment of a component of this application, not an embodiment of the entire component. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0045] 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 indications will also change accordingly.

[0046] In addition, when an element is described as being “fixed to” another element, it may be directly on the other element or one or more intervening elements may be present therebetween. When an element is described as being “connected to” another element, it may be directly connected to the other element or one or more intervening elements may be present therebetween.

[0047] 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 for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or", "and / or" or "and / or" appear 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 in which A and B are satisfied at the same time. 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 this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0048] The winding connection of the anode and cathode plates in wound batteries is unstable, especially at the ends of the winding. In the prior art, double-sided hot-melt adhesive is often used to connect the anode and cathode plates to provide a strong connection to the bare cells. However, this increases the thickness of the battery, reduces the energy density, and reduces the battery's operating efficiency.

[0049] To achieve the above purpose, the present application proposes a pole piece 10, see Figures 1 to 4The electrode piece 10 is used for a wound battery cell 20, and the electrode piece 10 includes a current collector 100 and a colloid portion 200. It should be noted that the current collector 100 of the electrode piece 10 includes a length direction along the length of the current collector 100, a width direction along the width of the current collector 100, and a thickness direction along the thickness of the current collector 100, wherein the length direction along the length of the current collector 100, the width direction along the width of the current collector 100, and the thickness direction along the thickness of the current collector 100 are all directions shown when the current collector 100 is not wound.

[0050] The current collector 100 includes a first empty foil area 110 and a coating area 120. An active material layer is provided on the coating area 120. It should be noted that the active material layer is the main component of the positive and negative electrodes of the battery, which contains active materials that can undergo electrochemical reactions. In some embodiments, the coating area 120 includes a first wall surface and a second wall surface that are relatively arranged, and the active material layer abuts the first wall surface and the second wall surface in a direction perpendicular to the thickness direction of the current collector 100. In some embodiments, the first empty foil area 110 does not include an active material layer. Along the thickness direction of the current collector 100, the first empty foil area 110 is provided with a first through hole 111. In some embodiments, the axial direction of the first through hole 111 is parallel to the thickness direction of the current collector 100.

[0051] The colloid portion 200 is disposed within the first through-hole 111, i.e., the second projection plane is defined as a plane perpendicular to the width of the current collector 100. The first hollow foil region 110 forms a third orthographic projection on the second projection plane, and the colloid portion 200 forms a fourth orthographic projection on the second projection plane, with the fourth orthographic projection completely overlapping the third orthographic projection. It should be noted that the material of the colloid portion 200 is a colloid having a bonding force. In some embodiments, the colloid portion 200 comprises a baseless hot melt adhesive. Furthermore, the colloid portion 200 is configured to melt upon heat during the hot pressing step of the battery cell 20 and connect to the battery cell 20, thereby providing bonding force to the battery cell 20. In some embodiments, the first through-hole 111 includes a first opening and a second opening. The outer contour of the first opening can have various configurations. In some embodiments, the first opening can be square. In other embodiments, the first opening can be circular. In other embodiments, the first opening can have a polygonal shape, etc., depending on the actual situation. The present embodiment uses a circular first opening as an example. Similarly, the outer contour of the second opening can have various configurations. In some embodiments, the second opening can have a square shape. In other embodiments, the second opening may be circular. In other embodiments, the second opening may be polygonal, etc., depending on the actual situation. The embodiment of the present application takes a circular second opening as an example.

[0052] Along the length direction of the current collector 100, see Figure 7The current collector 100 includes an inner end 130 and an outer end 140. In some embodiments, the inner end 130 and the outer end 140 are arranged relative to each other along the length direction of the current collector 100. The first empty foil area 110 is provided at the outer end 140. When the current collector 100 is in a wound state, the inner end 130 is provided at the inner ring of the current collector 100, that is, the inner end 130 is provided at the inner ring of the battery cell 20. The outer end 140 is provided at the outer ring of the current collector 100, that is, the outer end 140 is provided at the outer ring of the battery cell 20. By providing the first empty foil area 110 at the outer end 140, and the first empty foil area 110 including the colloid part 200, the thickness of the battery cell 20 is not increased, and the energy density of the battery cell 20 is ensured to remain unchanged, so that the colloid part 200 provides a connecting force to connect the wound battery cell 20.

[0053] The first projection plane is set as a plane perpendicular to the thickness direction of the current collector 100. The first empty foil area 110 forms a first orthographic projection on the first projection plane. The area of ​​the first orthographic projection is set as The colloid portion 200 forms a second orthographic projection on the first projection plane, and the area of ​​the second orthographic projection is set to ,area and area satisfy: , exemplary, area and area Ratio Can be 、 、 、 、 、 、 、 、 、 Etc. It should be noted that, The value of should be moderate. When the value is larger, the colloid part 200 provides a larger connection force, but the colloid part 200 accounts for a larger proportion in the first empty foil area 110, so that the structure of the current collector 100 is unstable, resulting in unstable winding of the battery cell 20. When the ratio is small, the proportion of the colloid part 200 in the first empty foil area 110 is small, so that the structure of the current collector 100 is stable. However, due to the small proportion of the colloid part 200, the connection force provided by the colloid part 200 is small, resulting in unstable winding of the battery cell 20. When the value of is moderate, the colloid portion 200 provides moderate connection force, and the structure of the current collector 100 is stable, so that the winding of the battery cell 20 is stable.

[0054] In some embodiments, the area and area satisfy: For example, the area and area Ratio Can be 、 、 、 、 Etc. It should be noted that, The value should be moderate.

[0055] The number of the first through holes 111 is multiple. For example, the first through holes 111 can be set to two, three, four, and so on. In the first empty foil area 110, the first through holes 111 are spaced apart. It should be noted that the first through holes 111 can be evenly spaced apart or unevenly spaced apart. In some embodiments, the first through holes 111 are evenly spaced apart in a direction perpendicular to the thickness direction of the current collector 100. In other embodiments, the current collector 100 includes a first wall perpendicular to the thickness direction, and along the first wall, the first through holes 111 are in a rectangular array. In other embodiments, the current collector 100 includes a first wall perpendicular to the thickness direction, and along the first wall, the first through holes 111 are in a circular array.

[0056] When the current collector 100 is in a wound state, the pole piece 10 is suitable for being wound with another pole piece with a different polarity to form a battery cell 20, and the outer end portion 140 is suitable for being arranged outside the other pole piece 10, that is, along the direction from the inner circle of the battery cell 20 to the outer circle of the battery cell 20, the outer end portion 140 is located on the outer circle of the other pole piece. It should be noted that after the current collector 100 is in a wound state, the other pole piece is connected to the pole piece 10 by heating. It should be noted that the polarity of the pole piece 10 is different from that of the other pole piece. In some embodiments, the polarity of the pole piece 10 is the anode, and the polarity of the other pole piece is the cathode. In other embodiments, the polarity of the pole piece 10 is the cathode, and the polarity of the other pole piece is the anode.

[0057] The pole piece 10 includes a pole ear portion 300, see Figures 1 to 4 In some embodiments, the tab portion 300 comprises an anode tab. The current collector 100 comprises a second hollow foil region 150. In some embodiments, along the length of the current collector 100, the second hollow foil region 150 is spaced apart from the first hollow foil region 110, and the coating region is located between the first hollow foil region 110 and the second hollow foil region 150. The tab portion 300 is connected to the second hollow foil region 150, which is located at the inner end portion 130.

[0058] The second projection plane is set as a plane perpendicular to the width direction of the current collector 100. The first empty foil area 110 forms a third orthographic projection on the second projection plane. The area of ​​the third orthographic projection is set as The colloid portion 200 forms a fourth orthographic projection on the second projection plane, and the area of ​​the fourth orthographic projection is set to ,area and area satisfy: , exemplary, area and area Ratio Can be 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 Etc. It should be noted that, The value should be moderate.

[0059] The third projection plane is set as a plane perpendicular to the length direction of the current collector 100. The first empty foil area 110 forms a fifth orthographic projection on the third projection plane. The area of ​​the fifth orthographic projection is set as The colloid portion 200 forms a sixth orthographic projection on the third projection plane, and the area of ​​the sixth orthographic projection is set to ,area and area satisfy: For example, the area and area Ratio Can be 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 Etc. It should be noted that, The value should be moderate.

[0060] It should be noted that the volume of the colloid portion 200 in the first empty foil area is , the volume of the first empty foil area 110 is In some embodiments, the volume and volume satisfy: , exemplary, area and area Ratio Can be 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 , etc. It should be noted that, The value should be moderate.

[0061] In the second aspect of the present application, a battery cell 20 is also provided. Figures 5 and 6, the battery cell 20 is a wound type, that is, the positive electrode, the negative electrode and the separator are wound to form the battery cell 20. It should be noted that the outer contour of the battery cell casing 30 can also be a variety of structures. In some embodiments, the battery cell 20 can be square. In other embodiments, the battery cell 20 can be circular. In other embodiments, the battery cell 20 can be polygonal, etc., depending on the actual situation. The embodiment of the present application takes a rectangular battery cell 20 as an example. The battery cell 20 includes any one of the pole pieces 10 and the battery cell casing 30 in the above embodiments. It should be noted that the outer contour of the battery cell casing 30 can also be a variety of structures. In some embodiments, the battery cell casing 30 can be square. In other embodiments, the battery cell casing 30 can be circular. In other embodiments, the battery cell casing 30 can be polygonal, etc., depending on the actual situation. The embodiment of the present application takes a rectangular battery cell casing 30 as an example. After the electrode 10 is wound, it is placed in the battery cell housing 30, wherein the colloid portion 200 ensures that the energy density of the battery cell 20 remains unchanged without increasing the thickness of the battery cell 20, so that the colloid portion 200 provides a connecting force to connect the wound battery cell 20. The battery cell housing 30 is used to load the electrode 10, and the battery cell housing 30 is used to provide a supporting force to the electrode 10 to limit the expansion of the electrode 10, so the battery cell housing 30 has a high rigidity. In some embodiments, the material of the battery cell housing 30 includes metal. In other embodiments, the material of the battery cell housing 30 includes alloy. Furthermore, the material of the battery cell housing 30 includes stainless steel to provide higher rigidity and stronger sealing.

[0062] In some embodiments, the polarity of the electrode piece 10 is anode, and the battery cell 20 further includes a cathode electrode piece. When the current collector 100 is in a wound state, the electrode piece 10 is suitable for winding with the cathode electrode piece, and the outer end portion 140 is suitable for being arranged outside the cathode electrode piece, that is, along the direction from the inner circle of the battery cell 20 to the outer circle of the battery cell 20, the outer end portion 140 is located at the outer circle of the cathode electrode piece; or, the polarity of the electrode piece 10 is cathode, and the battery cell 20 further includes an anode electrode piece 10. When the current collector 100 is in a wound state, the electrode piece 10 is suitable for winding with the anode electrode piece 10, and the outer end portion 140 is suitable for being arranged outside the anode electrode piece 10, that is, along the direction from the inner circle of the battery cell 20 to the outer circle of the battery cell 20, the outer end portion 140 is located at the outer circle of the anode electrode piece 10.

[0063] It should be noted that other contents of the wound battery cell 20 , the tab portion 300 and the active material layer disclosed in the present application can be referred to in the prior art and will not be described in detail here.

[0064] In addition, it should be noted that the preferred embodiments of the present application are given in the specification and drawings of this application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not intended to be additional limitations on the content of this application. The purpose of providing these embodiments is to make the understanding of the disclosure of this application more thorough and comprehensive. In addition, the above-mentioned technical features are further combined with each other to form various embodiments not listed above, which are all considered to be within the scope of the description of this application; further, it is obvious to those skilled in the art that improvements or changes can be made based on the above description, and all such improvements and changes should fall within the scope of protection of the claims attached to this application.

Claims

1. A pole piece, characterized in that: The pole piece is used for a wound battery cell, and the pole piece includes: A current collector, the current collector comprising a first empty foil area and a coating area, an active material layer is provided on the coating area, and along the thickness direction of the current collector, the first empty foil area is provided with a first through hole; a colloid portion, the colloid portion being disposed in the first through hole; Among them, along the length direction of the current collector, the current collector includes an inner end and an outer end, the first empty foil area is arranged at the outer end, and when the current collector is in a wound state, the inner end is arranged at the inner circle of the current collector, and the outer end is arranged at the outer circle of the current collector.

2. The pole piece according to claim 1, characterized in that: The first projection plane is set as a plane perpendicular to the thickness direction of the current collector, the first empty foil area forms a first orthographic projection on the first projection plane, and the area of ​​the first orthographic projection is set as The colloid part forms a second orthographic projection on the first projection plane, and the area of ​​the second orthographic projection is set to , the area And the area satisfy: .

3. The pole piece according to claim 2, characterized in that: The area And the area satisfy: .

4. The pole piece according to claim 1, characterized in that: There are a plurality of the first through holes, and in the first empty foil area, the first through holes are arranged at intervals.

5. The pole piece according to claim 1, characterized in that: When the current collector is in a wound state, the pole piece is suitable for being wound with another pole piece with a different polarity to form the battery core, and the outer end portion is suitable for being arranged outside the other pole piece.

6. The pole piece according to claim 1, characterized in that: The pole piece includes a pole ear portion, the current collector includes a second empty foil area, the pole ear portion is connected to the second empty foil area, and the second empty foil area is arranged at the inner end portion.

7. The pole piece according to claim 1, characterized in that: The second projection plane is set as a plane perpendicular to the width direction of the current collector, the first empty foil area forms a third orthographic projection on the second projection plane, and the area of ​​the third orthographic projection is set as The colloid part forms a fourth orthographic projection on the second projection plane, and the area of ​​the fourth orthographic projection is set to , the area And the area satisfy: .

8. The pole piece according to claim 1, characterized in that: The third projection plane is set as a plane perpendicular to the length direction of the current collector, the first empty foil area forms a fifth orthographic projection on the third projection plane, and the area of ​​the fifth orthographic projection is set as , the colloid part forms a sixth orthographic projection on the third projection plane, and the area of ​​the sixth orthographic projection is set to , the area And the area satisfy: .

9. A battery cell, characterized in that: The battery core is a wound type, and the battery core comprises: The pole piece according to any one of claims 1 to 8; A battery cell casing, wherein the battery cell casing is used to load the pole piece.

10. The battery cell according to claim 9, characterized in that: The polarity of the pole piece is an anode, the battery cell further comprises a cathode pole piece, when the current collector is in a wound state, the pole piece is suitable for being wound with the cathode pole piece, and the outer end portion is suitable for being arranged outside the cathode pole piece; Alternatively, the polarity of the electrode sheet is cathode, the battery cell further comprises an anode electrode sheet, and when the current collector is in a wound state, the electrode sheet is suitable for being wound with the anode electrode sheet, and the outer end portion is suitable for being arranged outside the anode electrode sheet.

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