A single battery and a welding corrosion prevention treatment method thereof

Abstract

The embodiment of the present application provides a single battery, comprising 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; the connection part of the bipolar plate and the lithium ion battery cell is provided with an anti-corrosion layer. The present application also 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 connection part of the bipolar plate and the lithium ion battery cell, so that the alloying reaction of the lithium negative electrode on the aluminum foil of the bipolar plate is effectively avoided, and the single battery with high voltage and high capacity is obtained. The present application has the advantages of simple structure, greatly reduced sealing difficulty, low cost and easy large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a single battery and a welding anti-corrosion treatment method thereof. BACKGROUND

[0002] Lithium ion batteries and sodium ion batteries develop almost synchronously, and the working principles of the two are similar, both of which work by moving ions between the positive electrode and the negative electrode. At present, the demand for low-cost energy storage battery technology is increasingly urgent, and how to reduce the cost and improve the battery performance is a research hotspot today.

[0003] Sodium ion batteries have low raw material cost, large cost reduction space, unique advantages in low temperature performance, fast charging and environmental adaptability, and are mutually compatible and complementary with lithium ion batteries. Lithium ion batteries and sodium ion batteries each have unique advantages, and if they can be used together, the performance of the battery will be greatly improved. As known, the graphite negative electrode of the lithium ion battery cannot be coated on the aluminum foil, and high-voltage high-capacity single batteries can be obtained by vertically connecting the bipolar sheet and the lithium / sodium two conventional cells, which avoids the alloying reaction of the lithium negative electrode on the aluminum foil. However, in the conventional lithium ion cell, copper and aluminum are directly in contact when the tab and the bipolar sheet are welded, and the copper and aluminum after welding are directly in contact with the electrolyte, causing the primary battery to be prone to electrochemical corrosion, which affects the performance of the battery. SUMMARY

[0004] The embodiment of the application provides a single battery and a welding anti-corrosion treatment method thereof, and aims to solve the problems that copper and aluminum are directly in contact when the tab and the bipolar sheet of the conventional lithium ion cell are welded, and the primary battery is prone to electrochemical corrosion.

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

[0006] As a preferred embodiment, the bipolar sheet and the negative tab of the lithium ion cell are welded and connected 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 2-10 microns.

[0008] As a preferred embodiment, the electrochemical corrosion prevention layer is a sealant layer or a solder layer. By applying a sealant layer or plating a solder layer, the contact between the electrolyte and the welding area can be effectively blocked, preventing the occurrence of electrochemical corrosion caused by the formation of a primary cell by two different active metals.

[0009] As a preferred embodiment, the sealant layer comprises one or a mixture of at least two of alkane rubber, polyolefin rubber, polyurethane, silicone glue, and fluorine rubber.

[0010] As a preferred embodiment, the bipolar plate comprises 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 arranged between the lithium battery positive electrode material layer and the edge of the current collector, a first reserved welding area is arranged between the first sealing area and the lithium battery positive electrode material layer, and the negative tab of the lithium ion battery cell is welded to the first reserved welding area.

[0012] A second sealing area is arranged between the sodium battery negative electrode material layer and the edge of the current collector, a second reserved welding area is arranged between the second sealing area and the sodium battery negative electrode material layer, and the positive tab of the sodium ion battery cell is welded to the second reserved welding area.

[0013] The current collector is an aluminum foil.

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

[0015] In another aspect, the present application also provides a welding corrosion prevention processing method for the single battery, comprising: arranging a corrosion prevention layer on the surface of the welding area, and then pressing, curing.

[0016] As a preferred embodiment, when the corrosion prevention layer is a sealant layer, the arrangement is achieved by coating.

[0017] As a preferred embodiment, the bonding pressure of the pressing is 0.5 MPa to 7 MPa, the pressing time is 4 s to 10 s, and the pressing temperature is 90°C to 120°C; the curing is at 50°C to 90°C for 2 days to 5 days.

[0018] The application vertically connects the sodium ion battery cell and the lithium ion battery cell through the bipolar plate, and sets the anticorrosion layer at the connection between the bipolar plate and the lithium ion battery cell, thereby effectively avoiding the alloying reaction of the lithium negative electrode on the aluminum foil of the bipolar plate and the electrochemical corrosion, and solving the problems of the direct contact between copper and aluminum, the easy electrochemical corrosion of the primary battery, and the like, which are caused by the welding of the tab of the conventional lithium ion battery cell and the bipolar plate. The application has high capacity and voltage, and can maintain high energy density. Through the structure of the application, the manufacturing process of the bipolar battery can be effectively simplified. The application has simple structure, greatly reduces the sealing difficulty, has low cost, and can be produced by using the existing equipment and is easy to scale production. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the drawings shown.

[0020] Fig. 1 is a schematic diagram of the stacking structure of the single battery cell in an embodiment of the present application;

[0021] Fig. 2 is an enlarged schematic diagram of the welding connection between the bipolar plate and the negative tab of the lithium ion battery cell. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0023] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, top, bottom, and the like), the directional indications are only used to explain the relative position relationship, movement condition, and the like between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0024] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] It should be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0026] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

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

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

[0029] In the embodiments of the present application, the number of series connection of the lithium ion battery cell 11, the sodium ion battery cell 12 and the bipolar plate 13 can be set according to the actual use voltage and capacity needs. Specifically, in the embodiments, two lithium ion battery cells 11 and two sodium ion battery cells 12 are provided, and three bipolar plates 13 are provided, forming a vertical series connection structure of "sodium ion battery cell-bipolar plate-lithium ion battery cell-bipolar plate-sodium ion battery cell-bipolar plate-lithium ion battery cell" from top to bottom, and the negative tab 121 of the outermost sodium ion battery cell and the positive tab 112 of the outermost lithium ion battery cell are connected with the outside as external tabs.

[0030] As a preferred embodiment, the anticorrosion layer 20 is an electrochemical anticorrosion layer; the electrochemical anticorrosion layer is coated on the surface of the welding area; and the thickness of the electrochemical anticorrosion layer is 2-10 microns. The thickness of the electrochemical anticorrosion layer can be set according to actual use needs, and can be 2 microns, or 3 microns, or 5 microns, or 7 microns, or 10 microns, etc. Through the thickness of the anticorrosion layer, the anticorrosion layer can be further ensured to tightly cover the surface of the welding area, to better prevent corrosion while ensuring the sealing of the connection of the components.

[0031] As a preferred embodiment, the electrochemical anticorrosion layer is a sealant layer or a solder layer. By coating a sealant layer or plating a solder layer, the contact of the electrolyte with the welding area can be effectively blocked, preventing the occurrence of electrochemical corrosion caused by the formation of a primary cell by two different active metals.

[0032] Specifically, in the embodiments, the electrochemical anticorrosion layer is a sealant layer. It can be understood that in other embodiments, the electrochemical anticorrosion layer can also be a solder layer.

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

[0034] As a preferred embodiment, the bipolar plate 13 includes a current collector 131, a lithium battery positive electrode material layer 132 provided on one side of the current collector 131, and a sodium battery negative electrode material layer 133 provided 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 implementation, the lithium battery positive electrode material layer 132 is provided with a first sealing area (not labeled in the figure) between the edge of the current collector 131, and the first sealing area is provided with a first reserved welding area (not labeled in the figure) between the lithium battery positive electrode material layer 132, and the negative tab 111 of the lithium ion battery cell 11 is welded to the first reserved welding area;

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

[0037] The current collector 131 is an aluminum foil. By providing a reserved welding area and a sealing area, it can further ensure that the corrosion-resistant layer tightly covers the surface of the welding area, thereby playing a better corrosion-resistant role.

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

[0039] In another aspect, the embodiments of the present application also provide a welding corrosion-resistant processing method of the single battery, which comprises: disposing a corrosion-resistant layer on the surface of the welding area, and then pressing and curing.

[0040] As a preferred implementation, when the corrosion-resistant layer is a sealing glue layer, the disposing is achieved by coating.

[0041] As a preferred embodiment, the bonding pressure of the pressing is 0.5MPa-7MPa (0.5MPa, or 1.5MPa, or 3MPa, or 5MPa, or 7MPa, etc. according to the actual needs of use), the pressing time is 4s-10s (0.5MPa, or 1.5MPa, or 3MPa, or 5MPa, or 7MPa, etc. according to the actual needs of use), and the pressing temperature is 90℃-120℃ (90℃, or 95℃, or 100℃, or 110℃, or 120℃, etc. according to the actual needs of use); the curing is 50℃-90℃ (50℃, or 65℃, or 70℃, or 80℃, or 90℃, etc. according to the actual needs of use) for 2-5 days (2 days, or 2.5 days, or 3 days, or 4 days, or 5 days, etc. according to the actual needs of use). By controlling the operation conditions of pressing and curing, the corrosion-resistant layer can be made to cover the surface of the welding area more closely, thereby effectively preventing the alloying reaction of the lithium negative electrode on the aluminum foil of the bipolar plate and being electrochemically corroded.

[0042] The sodium ion battery cell and the lithium ion battery cell are vertically connected by the bipolar plate, and the corrosion-resistant layer is arranged at the connection between the bipolar plate and the lithium ion battery cell, so that the lithium negative electrode is effectively prevented from being electrochemically corroded due to the alloying reaction on the aluminum foil of the bipolar plate when the tab of the conventional lithium ion battery cell is welded with the bipolar plate, and the problems of direct contact between copper and aluminum and easy electrochemical corrosion of the primary battery are solved. The vertical connection structure has high capacity and voltage, and can also maintain high energy density. The manufacturing process of the bipolar battery is effectively simplified by the structure. The structure is simple, the sealing difficulty is greatly reduced, the cost is low, the production and manufacturing can be realized by using the existing equipment, and the large-scale production is easy.

[0043] In the description of the present specification, the description referring to the terms "an embodiment", "an example", and the like means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0044] In addition, it should be understood that although the present specification is described in terms of embodiments, each embodiment does not necessarily contain only one independent technical solution, and the description of the specification is only for the sake of clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0045] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A single cell, characterized by, 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; an anticorrosion layer is arranged at the connection between the bipolar plate and the lithium ion battery cell; The bipolar plate and the negative tab of the lithium ion battery cell are welded to form a welding area; the welding area is provided with the anticorrosion layer; the anticorrosion layer is arranged on the surface of the welding area; The bipolar plate comprises a current collector, the current collector is welded with the negative tab, and the current collector is an aluminum foil; the negative tab is a copper negative tab.

2. The cell according to claim 1, wherein The anticorrosion layer is an electrochemical anticorrosion layer; the electrochemical anticorrosion layer is coated on the surface of the welding area; the thickness of the electrochemical anticorrosion layer is 2 μm to 10 μm.

3. The cell according to claim 2, wherein The electrochemical anticorrosion layer is a sealing glue layer or a solder layer.

4. The cell according to claim 3, wherein The sealing glue layer comprises one or a mixture of at least two of alkane rubber, polyolefin rubber, polyurethane, silicone glue, and fluororubber.

5. The cell according to claim 1, wherein The bipolar plate comprises 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.

6. The cell according to claim 5, wherein A first sealing area is arranged between the lithium battery positive electrode material layer and the edge of the current collector, a first reserved welding area is arranged between the lithium battery positive electrode material layer and the first sealing area, and the negative tab of the lithium ion battery cell is welded to the first reserved welding area; A second sealing area is arranged between the sodium battery negative electrode material layer and the edge of the current collector, a second reserved welding area is arranged between the sodium battery negative electrode material layer and the second sealing area, and the positive tab of the sodium ion battery cell is welded to the second reserved welding area.

7. The cell according to claim 1, wherein The single battery further comprises an aluminum plastic film, and the mixed battery cell is sealed in the aluminum plastic film.

8. The method of corrosion-proofing of the welding of a monobloc cell according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: The anticorrosion layer is arranged on the surface of the welding area, and then is pressed, aged, and cured.

9. The method of claim 8, wherein the welding corrosion prevention treatment is performed by applying a laser beam to the single cell. When the anticorrosion layer is a sealing glue layer, the arrangement is achieved by coating; The bonding pressure of the pressing is 0.5 MPa to 7 MPa, the pressing time is 4 s to 10 s, and the pressing temperature is 90 °C to 120 °C; the aging is 50 °C to 90 °C for 2 days to 5 days.

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