Pole piece and battery cell

Abstract

The utility model discloses a pole piece which comprises a current collector, a pole lug is welded on the current collector, an insulating layer is covered at the joint of the pole lug and the current collector, an accommodating notch is formed in the edge of the pole piece, and the accommodating notch is used for accommodating the pole lug insulating layer of another pole piece which is arranged in a paired manner. The utility model further discloses a battery cell adopting the pole piece. The technical scheme provided by the utility model has the beneficial effects that after the pole piece provided by the utility model is adopted to form a battery cell, as the area of one pole piece, which is opposite to the welding part of the tabs of the other pole piece, is the accommodating notch, lithium ions are not embedded in the charge-discharge cycle process of the battery cell, so that the lithium precipitation phenomenon can be prevented. And after the battery cell is formed, the tab insulating layer of one pole piece can be accommodated in the accommodating notch of the other pole piece, so that the thickness increase of the tab position caused by the tab insulating layer is counteracted, and the flatness of the battery cell is favorably maintained.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a pole piece which is beneficial to improving the flatness of a battery cell and a battery cell using the pole piece. Background Art

[0002] In recent years, lithium-ion batteries have been widely used as power sources in consumer electronic devices such as mobile phones, watches, tablets, notebooks, and even electric vehicles, which use lithium-ion batteries as power batteries.

[0003] Lithium-ion batteries have cells inside, such as Figure 1 As shown, the battery cell includes a cathode electrode a1-1, a separator a2 and an anode electrode a1-2 stacked in sequence. Among them, after the pole tab a3 is welded to the pole tab, burrs will be generated at the welding position. In order to prevent the burrs from piercing the diaphragm and causing a short circuit inside the battery cell, it is necessary to set an insulating material a4 (green glue) at the welding point of the pole tab. At this time, the active material on the other pole tab opposite to the pole tab cannot participate in the reaction, and lithium deposition will occur at this position as the battery cell is charged and discharged. In order to further prevent lithium deposition from occurring at the pole tab of the battery cell, an insulating material a4 (green glue) is set on the active material area on the other pole tab opposite to the pole tab, but this will increase the thickness of the pole tab, affect the flatness of the battery cell, and thus reduce the battery energy density of the battery cell. Utility Model Content

[0004] The main purpose of the utility model is to provide a battery core, aiming to solve the problem of poor flatness of the battery core after winding in the related art.

[0005] To achieve the above-mentioned purpose, one aspect of the utility model proposes a pole piece, which includes a current collector, a pole ear welded on the current collector, the connection between the pole ear and the current collector is covered with an insulating layer, and an accommodating notch is opened at the edge of the pole piece, which is used to accommodate the pole ear insulation layer of another paired pole piece.

[0006] In some embodiments, the pole piece further includes an active material layer coated on at least one side of the current collector, and the accommodating gap penetrates the active material layer and the current collector.

[0007] In some embodiments, active material layers are disposed on opposite sides of the current collector.

[0008] In some embodiments, a sink is constructed on both sides of the accommodating gap; the pole piece also includes a flexible insulating layer, which is attached to the outer surface of the sink, and the thickness of the flexible insulating layer is less than the depth of the sink.

[0009] In some embodiments, the pole piece is an anode pole piece, and the size of the accommodating gap is equal to the size of the pole tab insulation layer on the paired cathode pole piece.

[0010] In some embodiments, the electrode piece is a cathode electrode piece, and the size of the accommodating gap is larger than the size of the electrode tab insulation layer on the paired anode electrode piece.

[0011] In some embodiments, the tab is welded to the head of the current collector or the middle of the current collector.

[0012] In some embodiments, the active material layer is provided with a connection groove for accommodating the welding end of the electrode tab.

[0013] In some embodiments, the connecting groove and the receiving notch are opened at the edge of the same side of the active material layer.

[0014] Another aspect of the utility model provides a battery cell, which includes two pole pieces and an isolation membrane that are arranged in pair, the pole pieces of the two pole pieces are arranged opposite to each other, and the isolation membrane is sandwiched between the two pole pieces; wherein at least one pole piece is the pole piece and isolation membrane as described above.

[0015] Compared with the related art, the beneficial effects of the technical solution of the utility model are:

[0016] When the pole piece of the technical solution of the utility model is used to form a battery cell, since the area of ​​one pole piece opposite to the pole ear welding of another pole piece is a receiving notch, lithium ions will not be released during the charge and discharge cycle of the battery cell, thereby preventing the occurrence of lithium precipitation. Moreover, after the battery cell is formed, the pole ear insulation layer of one pole piece can be accommodated in the receiving notch of the other pole piece, thereby offsetting the increase in the thickness of the pole ear caused by the pole ear insulation layer, which is conducive to maintaining the flatness of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a battery cell structure of a related technology;

[0018] Figure 2 This is a schematic diagram of the structure of a pole piece in one embodiment of the utility model;

[0019] Figure 3 This is a schematic diagram of the structure of a battery cell in one embodiment of the utility model;

[0020] Figure 4 This is a schematic diagram of the structure of a pole piece in another embodiment of the utility model;

[0021] Figure 5 It is a schematic diagram of the structure of a battery cell in another embodiment of the utility model.

[0022] Reference numerals:

[0023] Figure 1 Middle: cathode electrode a1-1; anode electrode a1-2; isolation membrane a2; electrode ear a3; insulating material a4.

[0024] Figures 2 to 5 Middle: pole piece 100; accommodating notch 101; current collector 110; pole tab 120; pole tab insulation layer 130; active material layer 140; connecting groove 141; sink 142; flexible insulation layer 150; isolation film 200.

[0025] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the scheme in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, top, bottom, side...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0029] In addition, the descriptions involving "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features.

[0030] In view of the technical defects existing in the related art, this embodiment provides a pole piece 100. Figure 2 As shown, the pole piece 100 of this embodiment includes a current collector 110, an active material layer 140 and a pole tab 120. The active material layer 140 may be disposed only on one side of the current collector 110, or may be disposed on both opposite sides of the current collector 110.

[0031] The tab 120 is welded on the current collector 110, and in order to prevent the burrs at the welding position of the tab 120 from damaging other functional layers, the connection between the tab 120 and the current collector 110 is covered with a tab insulation layer 130. The tab insulation layer 130 has a certain hardness, so the burrs at the welding position of the tab 120 cannot pierce the tab insulation layer 130, thereby preventing the burrs at the welding position of the tab 120 from damaging other functional layers.

[0032] Continue to refer to Figure 2 As shown, an accommodating notch 101 is provided at the edge of the pole piece 100 of the present embodiment, and the accommodating notch 101 penetrates the active material layer 140 and the current collector 110. The accommodating notch 101 is used to accommodate the tab insulation layer 130 of another pole piece 100 that is paired during the process of forming the battery cell. In order to ensure that the accommodating notch 101 can accommodate the tab insulation layer 130 of another pole piece 100 that is paired, the accommodating notch 101 should be larger than or equal to the tab insulation layer 130 on the other pole piece 100 that is paired. However, it should be noted that when the pole piece 100 of the present embodiment is used as an anode pole piece and a cathode pole piece, the size relationship between the accommodating notch 101 and the tab insulation layer 130 is different. For example:

[0033] When the electrode piece 100 of this embodiment is an anode electrode piece, the size of the accommodating notch 101 of the anode electrode piece is equal to the size of the tab insulation layer 130 on the paired cathode electrode piece. The purpose is to ensure that the tab insulation layer 130 on the cathode electrode piece can be accommodated while the anode active material around the accommodating notch 101 can absorb the lithium ions released by the cathode active material around the tab insulation layer 130 of the cathode electrode piece, so as to prevent lithium deposition.

[0034] When the electrode piece 100 of the present embodiment is a cathode electrode piece, since lithium ions are released from the active material of the cathode electrode piece, as long as the size of the accommodation gap 101 of the cathode electrode piece is greater than or equal to the size of the tab insulating layer 130 on the paired anode electrode piece, the anode active material around the tab insulating layer 130 of the anode electrode piece does not need to absorb lithium ions, thereby preventing lithium plating.

[0035] In the embodiment of the present application, the battery cell may be a battery cell or a wound battery cell. Figure 2 and Figure 3 As shown, Figure 3 FIG. 1 shows a cell structure using the pole piece 100 of this embodiment. Figure 3As shown, in this embodiment, the two pole pieces 100 are arranged opposite to each other, wherein the welding position of the pole ear 120 of one pole piece 100 and the opening position of the receiving notch 101 of the other pole piece 100 are opposite to each other. Therefore, when winding to form a battery cell, the two pole pieces 100 and the isolation film 200 sandwiched between the two pole pieces 100 are bonded together. At this time, the pole ear insulation layer 130 of the welding position of the pole ear 120 of one pole piece 100 is received in the receiving notch 101 of the other pole piece 100.

[0036] Compared with the related art, when the pole piece 100 of this embodiment is used to make a battery cell, since the area of ​​one pole piece 100 opposite to the welding place of the pole ear 120 of another pole piece 100 is the accommodation gap 101, lithium ions will not be deintercalated during the charge and discharge cycle of the battery cell, thereby preventing the occurrence of lithium precipitation. Moreover, after the battery cell is formed, the pole ear insulation layer 130 of one pole piece 100 can be accommodated in the accommodation gap 101 of another pole piece 100, thereby offsetting the increase in thickness of the pole ear 120 caused by the pole ear insulation layer 130, which is conducive to maintaining the flatness of the battery cell.

[0037] Furthermore, the tab 120 may be welded to the head of the current collector 110 or the middle of the current collector 110. In order to weld the tab 120 to the current collector 110, as shown in FIG. Figure 2 As shown, the active material layer 140 is provided with a connection groove 141 for accommodating the welding end of the electrode tab 120. The connection groove 141 is formed by first providing the active material layer 140 on the current collector 110 and then thinning the active material layer 140 until the current collector 110 is exposed. Of course, the active material layer 140 can also be formed by a mask method during the process of forming the active material layer 140, so that the connection groove 141 is formed in the area covered by the mask.

[0038] It is understandable that when the electrode sheet 100 of this embodiment is used to make a battery cell, in order to make the cathode electrode tab 120 and the anode electrode tab 120 extend on the same side of the battery cell, the connection groove 141 and the accommodating notch 101 are opened at the edge of the same side of the active material layer 140. Of course, if there are special requirements for the arrangement positions of the cathode electrode tab 120 and the anode electrode tab 120, the connection groove 141 and the accommodating notch 101 can also be opened at the edges of different sides of the active material layer 140.

[0039] The pole piece 100 of the present embodiment can be an anode pole piece 100 or a cathode pole piece 100. When the pole piece 100 of the present embodiment is a cathode pole piece 100, the current collector 110 uses aluminum foil. Correspondingly, when the pole piece 100 is a cathode pole piece 100, the active material layer 140 is made of one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium iron phosphate. Lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium iron phosphate generates lithium ions during the charging process of the lithium-ion battery, and these lithium ions are transferred to the anode pole piece 100 through the isolation membrane 200 and embedded in the active material layer 140 of the anode pole piece 100. The electrons generated in the cathode pole piece 100 cannot pass through the isolation membrane 200, and are thus transferred to the anode through the wire. When the pole piece 100 of the present embodiment is used as the anode pole piece 100, the current collector 110 uses copper foil. Accordingly, in order to embed lithium ions in the anode electrode sheet 100, when the electrode sheet 100 is used as the anode electrode sheet 100, the active material layer 140 is made of graphite or soft or hard carbon to embed lithium ions generated by the cathode during the charging process of the battery. During the discharge process of the battery, the lithium ions embedded in the anode active material layer 140 are separated and transferred to the cathode electrode sheet 100 through the isolation film 200.

[0040] like Figure 4 As shown, in some embodiments, a sink 142 is constructed on both sides of the accommodating notch 101. The pole piece 100 of this embodiment also includes a flexible insulating layer 150, which is attached to the outer surface of the sink 142. Optionally, the sink 142 is formed along the opposite edge of the accommodating notch 101. Of course, according to actual needs, the sink 142 can be formed along the edge of the entire accommodating notch 101. In order to improve the flatness of the pole piece 100, the thickness of the flexible insulating layer 150 should be less than the depth of the sink 142. The flexible insulating layer 150 can cover all of the accommodating notch 101, or it can cover part of the accommodating notch 101. The flexible insulating layer 150 of this embodiment has high toughness, so that when the battery cell of this embodiment is wound, the accommodating notch 101 can be prevented from tearing. Moreover, the flexible insulating layer 150 of this embodiment is also flexible, that is, when the flexible insulating layer 150 is squeezed, a certain deformation may occur. Combined with Figure 5 As shown, when the pole piece 100 of this embodiment is used to form a battery cell, when the pole tab insulation layer 130 of another pole piece 100 is accommodated in the accommodating notch 101, the flexible insulation layer 150 will also sink into the accommodating notch 101, so as not to hinder the pole tab insulation layer 130 of the other pole piece 100 from being accommodated in the accommodating notch 101, which is beneficial to maintaining the flatness of the battery cell.

[0041] In some embodiments, a battery cell is also provided, such as Figure 3 or Figure 5As shown, the battery cell of this embodiment includes the pole piece 100 of the aforementioned embodiment. Since the pole piece 100 of the aforementioned embodiment is adopted, lithium ions will not be deintercalated during the charge and discharge cycle of the battery cell, thereby preventing the occurrence of lithium precipitation. Moreover, after the battery cell is formed, the tab insulation layer 130 of one pole piece 100 can be accommodated in the accommodation notch 101 of another pole piece 100, thereby offsetting the increase in thickness of the tab 120 caused by the tab insulation layer 130, which is beneficial to maintaining the flatness of the battery cell.

[0042] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.

Claims

1. A pole piece, comprising a current collector, a pole ear welded on the current collector, and a pole ear insulation layer covering the connection between the pole ear and the current collector, characterized in that: An accommodating notch is provided at the edge of the pole piece, and the accommodating notch is used to accommodate the tab insulation layer of another pole piece arranged in a paired manner.

2. The pole piece according to claim 1, characterized in that: The pole piece further includes an active material layer coated on at least one side of the current collector, and the accommodating notch penetrates the active material layer and the current collector.

3. The pole piece according to claim 2, characterized in that: The active material layers are disposed on opposite sides of the current collector.

4. The pole piece according to claim 3, characterized in that: The two sides of the accommodating gap are constructed with sinking platforms; the pole piece also includes a flexible insulating layer, which is attached to the outer surface of the sinking platform, and the thickness of the flexible insulating layer is less than the depth of the sinking platform.

5. The pole piece according to claim 1, characterized in that: The pole piece is an anode pole piece, and the size of the accommodating gap is equal to the size of the pole tab insulation layer on the paired cathode pole piece.

6. The pole piece according to claim 4, characterized in that: The pole piece is a cathode pole piece, and the size of the accommodating gap is greater than or equal to the size of the pole tab insulation layer on the paired anode pole piece.

7. The pole piece according to any one of claims 1 to 6, characterized in that: The tab is welded to the head of the current collector or the middle of the current collector.

8. The pole piece according to claim 3, characterized in that: The active material layer is provided with a connection groove for accommodating the welding end of the electrode tab.

9. The pole piece according to claim 8, characterized in that: The connecting groove and the accommodating notch are opened at the edge of the same side of the active material layer.

10. A battery cell, characterized in that: It comprises two pole pieces and an isolation membrane arranged in pairs, wherein the two pole pieces are arranged opposite to each other, and the isolation membrane is sandwiched between the two pole pieces; wherein at least one pole piece is the pole piece as claimed in any one of claims 1 to 9.

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