Single battery and welding anti-corrosion treatment method thereof

Abstract

The embodiment of the invention provides a single battery. The single battery comprises a mixed battery cell, the mixed battery cell comprises at least one lithium ion battery cell, at least one sodium ion battery cell and at least one bipolar plate, the sodium ion battery cell, the bipolar plate and the lithium ion battery cell are sequentially stacked, and the sodium ion battery cell, the bipolar plate and the lithium ion battery cell are sequentially connected in series; and an anti-corrosion layer is arranged at the joint of the bipolar plate and the lithium ion battery cell. The invention further provides a welding anti-corrosion treatment method of the single battery. The sodium ion battery cell and the lithium ion battery cell are vertically connected in series through the bipolar plate, and the anti-corrosion layer is arranged at the joint of the bipolar plate and the lithium ion battery cell, so that a high-voltage and high-capacity single battery is obtained, and a lithium negative electrode is effectively prevented from being subjected to an alloying reaction on an aluminum foil of the bipolar plate to be subjected to electrochemical corrosion. The structure is simple, the sealing difficulty is greatly reduced, the cost is low, and large-scale production is easy.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to a single cell and a welding anti-corrosion treatment method thereof. Background Art

[0002] Lithium-ion batteries and sodium-ion batteries have developed almost simultaneously. Their working principles are similar, both relying on the movement of ions between the positive and negative electrodes. At present, the demand for low-cost energy storage battery technology is becoming more and more urgent. How to reduce costs and improve battery performance is a research hotspot today.

[0003] Sodium-ion batteries have low raw material costs and great room for cost reduction. They have unique advantages in low-temperature performance, fast charging, and environmental adaptability. They are compatible with lithium-ion batteries and complement each other's strengths and weaknesses. Lithium-ion batteries and sodium-ion batteries each have their own unique advantages. If they can be mixed and used together, the performance of the battery will be greatly improved. As we all know, negative electrodes such as graphite in lithium-ion batteries cannot be coated on aluminum foil. By vertically connecting bipolar sheets and two conventional lithium / sodium cells in series, high-voltage and high-capacity single cells can be obtained, avoiding the alloying reaction of the lithium negative electrode on the aluminum foil. However, in conventional lithium-ion cells, there will be a problem of direct contact between copper and aluminum when the pole ear and the bipolar pole piece are welded. After welding, copper and aluminum are in direct contact with the electrolyte, causing the original battery to be prone to electrochemical corrosion, which in turn affects the performance of the battery. Summary of the invention

[0004] The embodiment of the present invention provides a single cell and a method for treating welding corrosion thereof, aiming to solve the problem that direct contact between copper and aluminum occurs when welding the tabs and bipolar pole pieces of conventional lithium-ion batteries, causing the original battery to be prone to electrochemical corrosion.

[0005] To achieve the above-mentioned objectives, on the one hand, an embodiment of the present invention provides a single cell, comprising a hybrid battery cell; the hybrid battery cell comprises at least one lithium ion battery cell, at least one sodium ion battery cell and at least one bipolar sheet, the sodium ion battery cell, the bipolar sheet and the lithium ion battery cell are stacked in sequence, and the sodium ion battery cell, the bipolar sheet and the lithium ion battery cell are connected in series in sequence; an anti-corrosion layer is provided at the connection between the bipolar sheet and the lithium ion battery cell.

[0006] As a preferred embodiment, the bipolar sheet is welded to the negative electrode ear of the lithium-ion battery cell to form a welding area; the welding area is provided with the anti-corrosion layer.

[0007] As a preferred embodiment, the anti-corrosion layer is an electrochemical anti-corrosion layer; the electrochemical anti-corrosion layer is coated on the surface of the welding area; the thickness of the electrochemical anti-corrosion layer is 2 μm to 10 μm.

[0008] As a preferred embodiment, the electrochemical anti-corrosion layer is a sealing glue layer or a solder layer. By applying a sealing glue layer or plating a solder layer, the contact between the electrolyte and the welding area can be effectively blocked to prevent the two metals with different activities from forming a primary battery and causing electrochemical corrosion.

[0009] As a preferred embodiment, the sealing glue layer includes one or a mixture of at least two of alkane rubber, polyolefin rubber, polyurethane, organic silicone and fluororubber.

[0010] As a preferred embodiment, the bipolar sheet includes a current collector, a lithium battery positive electrode material layer arranged on one side of the current collector, and a sodium battery negative electrode material layer arranged on the other side of the current collector; the area of ​​the lithium battery positive electrode material layer or the area of ​​the sodium battery negative electrode material layer is smaller than the area of ​​the side of the current collector.

[0011] As a preferred embodiment, a first sealing area is provided between the lithium battery positive electrode material layer and the edge of the current collector, a first reserved welding area is provided between the first sealing area and the lithium battery positive electrode material layer, and the negative electrode ear of the lithium ion battery cell is welded and connected to the first reserved welding area;

[0012] A second sealing area is provided between the sodium-ion negative electrode material layer and the edge of the current collector, a second reserved welding area is provided between the second sealing area and the sodium-ion negative electrode material layer, and the positive electrode ear of the sodium-ion battery cell is welded and connected to the second reserved welding area;

[0013] The current collector is aluminum foil.

[0014] As a preferred embodiment, the single battery further includes an aluminum-plastic film, and the hybrid battery cell is sealed in the aluminum-plastic film.

[0015] On the other hand, an embodiment of the present invention further provides a method for treating welding corrosion of the single cell, comprising: providing an anti-corrosion layer on the surface of the welding area, and then pressing and aging.

[0016] As a preferred embodiment, when the anti-corrosion layer is a sealing glue layer, the setting is achieved by coating.

[0017] As a preferred embodiment, the lamination bonding pressure is 0.5MPa-7MPa, the lamination time is 4s-10s, the lamination temperature is 90°C-120°C, and the aging is 50°C-90°C for 2-5 days.

[0018] The present application connects sodium ion cells and lithium ion cells vertically in series through bipolar sheets, and sets an anti-corrosion layer at the connection between the bipolar sheets and the lithium ion cells. While obtaining high-voltage, high-capacity single cells, it effectively avoids the electrochemical corrosion of the lithium negative electrode due to alloying reaction on the aluminum foil of the bipolar sheet. It can effectively solve the problems of direct contact between copper and aluminum when welding the pole ears and bipolar sheets of conventional lithium ion cells, which makes the original battery very prone to electrochemical corrosion. The present application adopts a vertical series structure, has a higher capacity and voltage, and can also maintain a higher energy density. The structure of the present application can effectively simplify the manufacturing process of bipolar batteries. The present application has a simple structure, greatly reduces the difficulty of sealing, has a low cost, can be manufactured with existing equipment, and is easy to mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 is a schematic diagram of a stacking structure of a single cell according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the enlarged structure of the welding connection between the bipolar sheet and the negative pole ear of the lithium-ion battery cell. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, top, bottom...), 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.

[0024] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0026] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is 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 the present invention.

[0027] Specifically, on the one hand, Figure 1 to Figure 2 As shown, an embodiment of the present invention provides a single battery, including a hybrid battery cell 10; the hybrid battery cell 10 includes at least one lithium ion battery cell 11, at least one sodium ion battery cell 12 and at least one bipolar sheet 13, the sodium ion battery cell 12, the bipolar sheet 13 and the lithium ion battery cell 11 are stacked in sequence, and the sodium ion battery cell 12, the bipolar sheet 13 and the lithium ion battery cell 11 are connected in series in sequence; an anti-corrosion layer 20 is provided at the connection between the bipolar sheet 13 and the lithium ion battery cell 11.

[0028] As a preferred embodiment, the bipolar sheet 13 is welded to the negative electrode ear 111 of the lithium-ion battery cell 11 to form a welding area; the anti-corrosion layer 20 is provided in the welding area.

[0029] In the embodiment of the present application, the number of lithium-ion cells 11, sodium-ion cells 12 and bipolar sheets 13 connected in series can be set according to the actual use voltage and capacity requirements. Specifically, in the present embodiment, two lithium-ion cells 11 and two sodium-ion cells 12 are provided, and three bipolar sheets 13 are provided, forming a vertical series structure of "sodium-ion cell-bipolar sheet-lithium-ion cell-bipolar sheet-sodium-ion cell-bipolar sheet-lithium-ion cell" from top to bottom, and the negative pole ear 121 of the outermost sodium-ion cell and the positive pole ear 112 of the outermost lithium-ion cell are both connected to the outside as external lead ears.

[0030] As a preferred embodiment, the anti-corrosion layer 20 is an electrochemical anti-corrosion layer; the electrochemical anti-corrosion layer is coated on the surface of the welding area; the thickness of the electrochemical anti-corrosion layer is 2μm to 10μm. The thickness of the electrochemical anti-corrosion layer can be set according to actual use needs, and can be 2μm, 3μm, 5μm, 7μm, 10μm, etc. Through the thickness of the anti-corrosion layer, it can be further ensured that the anti-corrosion layer is tightly covered on the surface of the welding area, which plays a better anti-corrosion role while ensuring the sealing of the connection of each component.

[0031] As a preferred embodiment, the electrochemical anti-corrosion layer is a sealing glue layer or a solder layer. By applying a sealing glue layer or plating a solder layer, the contact between the electrolyte and the welding area can be effectively blocked to prevent the two metals with different activities from forming a primary battery and causing electrochemical corrosion.

[0032] Specifically, in this embodiment, the electrochemical anti-corrosion layer is a sealing glue layer. It is understandable that in other embodiments, the electrochemical anti-corrosion layer may also be a solder layer.

[0033] As a preferred embodiment, the sealing glue layer includes one or a mixture of at least two of alkane rubber, polyolefin rubber, polyurethane, organic silicone and fluororubber. The material of the sealing glue layer can be selected according to the actual use needs. Specifically, in this embodiment, the sealing glue layer is alkane rubber.

[0034] As a preferred embodiment, the bipolar sheet 13 includes a current collector 131, a lithium battery positive electrode material layer 132 arranged on one side of the current collector 131, and a sodium battery negative electrode material layer 133 arranged on the other side of the current collector 131; the area of ​​the lithium battery positive electrode material layer 132 or the area of ​​the sodium battery negative electrode material layer 133 is smaller than the area of ​​the side of the current collector 131.

[0035] As a preferred embodiment, a first sealing area (not marked in the figure) is provided between the lithium battery positive electrode material layer 132 and the edge of the current collector 131, a first reserved welding area (not marked in the figure) is provided between the first sealing area and the lithium battery positive electrode material layer 132, and the negative electrode ear 111 of the lithium ion battery cell 11 is welded and connected to the first reserved welding area;

[0036] A second sealing area (not marked in the figure) is provided between the sodium negative electrode material layer 133 and the edge of the current collector 131, and a second reserved welding area (not marked in the figure) is provided between the second sealing area and the sodium negative electrode material layer 133, and the positive electrode ear 122 of the sodium ion battery cell 12 is welded and connected to the second reserved welding area;

[0037] The current collector 131 is aluminum foil. By setting the reserved welding area and the sealing area, it can be further ensured that the anti-corrosion layer is tightly covered on the surface of the welding area, thereby playing a better anti-corrosion role.

[0038] As a preferred embodiment, the single battery further includes an aluminum-plastic film 30 , and the hybrid battery cell 10 is sealed in the aluminum-plastic film 30 .

[0039] On the other hand, an embodiment of the present invention further provides a method for treating welding corrosion of the single cell, comprising: providing an anti-corrosion layer on the surface of the welding area, and then pressing and aging.

[0040] As a preferred embodiment, when the anti-corrosion layer is a sealing glue layer, the setting is achieved by coating.

[0041] As a preferred embodiment, the lamination bonding pressure is 0.5MPa to 7MPa (depending on the actual use requirements, it can be 0.5MPa, or 1.5MPa, or 3MPa, or 5MPa, or 7MPa, etc.), the lamination time is 4s to 10s (depending on the actual use requirements, it can be 0.5MPa, or 1.5MPa, or 3MPa, or 5MPa, or 7MPa, etc.), the lamination temperature is 90 The temperature of the lamination is 50°C to 90°C (50°C, 65°C, 70°C, 80°C, 90°C, etc.) and the aging is 2 to 5 days (2 days, 2.5 days, 3 days, 4 days, 5 days, etc.). By controlling the lamination and aging operating conditions, the anti-corrosion layer can be more tightly covered on the surface of the welding area, thereby effectively preventing the lithium negative electrode from being electrochemically corroded by alloying reaction on the aluminum foil of the bipolar sheet.

[0042] The present application connects sodium ion cells and lithium ion cells vertically in series through bipolar sheets, and sets an anti-corrosion layer at the connection between the bipolar sheets and the lithium ion cells. While obtaining high-voltage, high-capacity single cells, it effectively avoids the electrochemical corrosion of the lithium negative electrode due to alloying reaction on the aluminum foil of the bipolar sheet. It can effectively solve the problems of direct contact between copper and aluminum when welding the pole ears and bipolar sheets of conventional lithium ion cells, which makes the original battery very prone to electrochemical corrosion. The present application adopts a vertical series structure, has a higher capacity and voltage, and can also maintain a higher energy density. The structure of the present application can effectively simplify the manufacturing process of bipolar batteries. The present application has a simple structure, greatly reduces the difficulty of sealing, has a low cost, can be manufactured with existing equipment, and is easy to mass produce.

[0043] In the description of this specification, the description with reference to the terms "an embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0044] In addition, it should be understood that although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A single cell battery, characterized in that: It comprises a hybrid battery cell; the hybrid battery cell comprises at least one lithium ion battery cell, at least one sodium ion battery cell and at least one bipolar sheet, the sodium ion battery cell, the bipolar sheet and the lithium ion battery cell are stacked in sequence, and the sodium ion battery cell, the bipolar sheet and the lithium ion battery cell are connected in series in sequence; an anti-corrosion layer is provided at the connection between the bipolar sheet and the lithium ion battery cell.

2. The single cell according to claim 1, characterized in that: The bipolar sheet is welded to the negative pole ear of the lithium-ion battery cell to form a welding area; the welding area is provided with the anti-corrosion layer.

3. The single cell according to claim 2, characterized in that: The anti-corrosion layer is an electrochemical anti-corrosion layer; the electrochemical anti-corrosion layer is coated on the surface of the welding area; the thickness of the electrochemical anti-corrosion layer is 2 μm to 10 μm.

4. The single cell according to claim 3, characterized in that: The electrochemical anti-corrosion layer is a sealing glue layer or a solder layer.

5. The single cell according to claim 4, characterized in that: The sealing glue layer comprises one or a mixture of at least two of alkane rubber, polyolefin rubber, polyurethane, organic silica gel and fluororubber.

6. The single cell according to claim 2, characterized in that: The bipolar sheet includes a current collector, a lithium battery positive electrode material layer arranged on one side of the current collector, and a sodium battery negative electrode material layer arranged on the other side of the current collector; the area of ​​the lithium battery positive electrode material layer or the area of ​​the sodium battery negative electrode material layer is smaller than the area of ​​the side of the current collector.

7. The single cell according to claim 6, characterized in that: A first sealing area is provided between the lithium battery positive electrode material layer and the edge of the current collector, a first reserved welding area is provided between the first sealing area and the lithium battery positive electrode material layer, and the negative electrode ear of the lithium ion battery cell is welded and connected to the first reserved welding area; A second sealing area is provided between the sodium-ion negative electrode material layer and the edge of the current collector, a second reserved welding area is provided between the second sealing area and the sodium-ion negative electrode material layer, and the positive electrode ear of the sodium-ion battery cell is welded and connected to the second reserved welding area; The current collector is aluminum foil.

8. The single cell according to claim 1, characterized in that: The single battery also includes an aluminum-plastic film, and the hybrid battery core is sealed in the aluminum-plastic film.

9. The welding anti-corrosion treatment method for a single cell according to any one of claims 1 to 8, characterized in that: include: The anti-corrosion layer is arranged on the surface of the welding area, and then pressed and cured.

10. The welding anti-corrosion treatment method of a single cell according to claim 9, characterized in that: When the anti-corrosion layer is a sealing glue layer, the setting is achieved by coating; The bonding pressure of the pressing is 0.5MPa-7MPa, the pressing time is 4s-10s, the pressing temperature is 90°C-120°C; the aging is 50°C-90°C for 2-5 days.

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