CN215377445U - Composite current collector, battery and object - Google Patents

Abstract

The application discloses compound mass flow body relates to secondary battery technical field. The composite current collector comprises: a support layer made of a polymer; a first conductor layer disposed on one side of the support layer; a second conductor layer disposed on the other side of the support layer; a welding area; wherein no polymer is present between the first conductor layer and the second conductor layer in the bonding region. This application does not have the welding area of polymer through the setting, when welding utmost point ear, need not pierce through the supporter layer and can realize the electric connection each other between first conductor layer and the second conductor, and then derives the electric current that produces on first conductor layer and the second conductor layer, solves the utmost point ear welding problem and the conductor layer of the compound mass flow body among the prior art and switches on the problem.

Description

Composite current collector, battery and object

Technical Field

The application relates to the technical field of secondary batteries, in particular to a composite current collector, a battery and an object.

Background

The lithium ion battery is formed by winding or overlapping basic unit structures, wherein the basic unit structures are a positive electrode/a diaphragm/a negative electrode. The positive electrode and the negative electrode are places where electrochemical reaction occurs, and current generated by the electrochemical reaction is collected and led out through current collectors in the positive electrode and the negative electrode; the diaphragm is responsible for separating positive pole and negative pole, avoids positive negative pole to take place to contact and appears the short circuit.

The current collector is usually configured by using a copper foil material for the negative electrode and an aluminum foil material for the positive electrode. Because of the use of metal materials, the positive and negative current collectors occupy a relatively large proportion (about 8%) in the total weight of the battery core, so that the reduction of the weight of the current collectors is an effective way to improve the energy density (kWh/kg) of the lithium ion battery, and the chinese patent applications CN106654285A and CN101071860A can prepare low-density current collectors by a method of preparing conductive coatings on the surfaces of flexible substrates. For example, chinese patent application publication No. CN110277532A discloses a method and an apparatus for processing a secondary battery current collector, in which a foil is connected to a composite current collector and serves as a tab of the composite current collector, so as to transfer current from a battery cell. However, the above technical solutions have the following disadvantages: 1. the tab is only connected with the metal conductor layer on one side, so that the metal conductor layers on the two sides can lead out current difficultly; 2. soldering is difficult because the metal conductor layers on both sides of the composite current collector are typically thin.

In order to solve these problems, technicians have made many efforts on the structure of the current collector and the manner of welding. The invention of application publication number CN110165223A discloses a composite current collector, which has a porous structure, and a conductor layer is arranged in the hole, so that the conduction of metal conductor layers at two sides of the composite current collector can be realized. However, the current collector needs to be punched, and the conductor layer inside the hole is difficult to manufacture, poor in conduction effect and not beneficial to popularization and application of the composite current collector. The utility model discloses an ultrasonic bonding tool and welding equipment of authority bulletin number CN 208051145U. The polymer layer of the welding area is penetrated through the extrusion effect of the conical structure of the welding head during welding, the metal conductor layers of the welding area are welded together, and the mutual conduction of the two metal conductor layers is realized while the welding is realized. However, such a soldering process easily causes over-soldering, damages a metal conductor layer in a soldering area, and has low soldering strength and poor conductivity.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a compound mass flow body solves the utmost point ear welding problem of compound mass flow body among the prior art, solves the problem that compound mass flow body both sides conductor layer is difficult to realize switching on simultaneously.

In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions: a composite current collector, comprising: a support layer made of a polymer; a first conductor layer disposed on one side of the support layer; a second conductor layer disposed on the other side of the support layer; a welding area; wherein no polymer is present between the first conductor layer and the second conductor layer in the bonding region.

In above-mentioned technical scheme, this application embodiment does not have the welding area of polymer through the setting, when welding utmost point ear, need not pierce through the supporter layer and can realize the electric connection each other between first conductor layer and the second conductor layer, and then derives the electric current that produces on first conductor layer and the second conductor layer, solves the utmost point ear welding problem and the conductor layer of the compound mass flow body among the prior art and switches on the problem.

Further, according to the embodiment of the present application, wherein the support layer is made of one or more materials selected from PET, PP, PE, PI, and polyarylsulfone.

Further, according to the embodiment of the present application, wherein the first conductor layer and the second conductor layer are made of aluminum, copper, nickel, silver, gold, carbon, stainless steel or an alloy thereof.

Further, according to the embodiment of the present application, wherein the thickness of the first conductor layer and the second conductor layer is 0.2-5 μm.

Further, according to the embodiment of the present application, wherein the area of the soldering region occupies 0.5-30% of the area of the first conductor layer.

Further, according to the embodiment of the present application, wherein the shape of the welding area is a rectangle, a circle, an ellipse, a sector, a polygon or an irregular figure.

Further, according to the embodiment of the present application, wherein the welding area is located at an edge of the composite current collector.

Further in accordance with an embodiment of the present application, wherein the solder area is formed by the first conductor layer and the second conductor layer having a length longer than the support layer.

Further, according to the embodiment of the application, the welding area is formed by hollowing out the support body layer.

Further, according to the embodiment of the present application, wherein, in the soldering region, the first conductor layer and the second conductor layer are connected by a conductive adhesive.

Further in accordance with an embodiment of the present application, wherein, in the soldering region, the thickness of the first conductor layer and/or the second conductor layer is greater than the remaining portion thereof, a thickened region is formed.

Further, according to an embodiment of the application, wherein the edge of the thickened area is 0.5-10mm wider than the welding area.

In order to achieve the above object, an embodiment of the present application further discloses a method for preparing a composite current collector, including the following steps: and pressing the conductor layer material into a conductor layer, and compounding the conductor layer on two sides of the support layer.

Further, according to the embodiment of the present application, the conductor layer and the support layer are connected by an adhesive.

Further, according to the embodiment of the present application, wherein the conductor layer is thinned by a chemical or electrochemical method.

In order to achieve the above object, an embodiment of the present application further discloses a battery, which is characterized by comprising a positive electrode plate, a negative electrode plate, a separator and an electrolyte, wherein the positive electrode plate and/or the negative electrode plate comprises the current collector as described above.

In order to achieve the purpose, the embodiment of the application also discloses an object, which is characterized by comprising the secondary battery.

Further, according to the embodiment of the application, the object is an electronic product or an electric vehicle.

Compared with the prior art, the method has the following beneficial effects: this application does not have the welding area of polymer through the setting, when welding utmost point ear, need not pierce through the supporter layer and can realize the electric connection each other between first conductor layer and the second conductor, and then derives the electric current that produces on first conductor layer and the second conductor layer, solves the utmost point ear welding problem and the conductor layer of the compound mass flow body among the prior art and switches on the problem.

Drawings

The present application is further described below with reference to the drawings and examples.

Fig. 1 is a schematic structural view of a composite current collector in an embodiment of the present application.

Fig. 2 is a top view of the composite current collector shown in fig. 1.

Fig. 3 is a schematic structural view of a composite current collector in a second embodiment of the present application.

Fig. 4 is a schematic structural view of a composite current collector in a third embodiment of the present application.

Fig. 5 is a schematic structural view of a composite current collector in a fourth embodiment of the present application.

Fig. 6 is a schematic structural view of a composite current collector in a fifth embodiment of the present application

In the attached drawings

1. Support layer 2, first conductor layer 3, second conductor layer

4. Soldering zone 5, conductive glue

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clear and fully described, embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of some embodiments of the invention and are not limiting of the invention, and that all other embodiments obtained by those of ordinary skill in the art without the exercise of inventive faculty are within the scope of the invention.

In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "a," "an," "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

For the purposes of simplicity and explanation, the principles of the embodiments are described by referring mainly to examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that the embodiments may be practiced without these specific details. In some instances, well-known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments. In addition, all embodiments may be used in combination with each other.

Fig. 1 shows a schematic structural diagram of a composite current collector, and fig. 2 is a top view of the composite current collector shown in fig. 1. As shown in fig. 1-2, the composite current collector includes a support layer 1, a first conductor layer 2 and a second conductor layer 3, wherein the first conductor layer 2 and the second conductor layer 3 are respectively compounded on two sides of the support layer 1. Wherein, the support layer 1 is made of polymer material for providing supporting force. The first conductor layer 2 and the second conductor layer 3 are generally made of the same conductive material and are used for conducting current out.

In order to solve the problem of tab welding of the composite current collector, the above-mentioned composite current collector further comprises at least one welding zone 4, in which welding zone 4 there is no polymer between the first conductor layer 2 and the second conductor layer 3 for preparing the support layer 1. The welding area 4 without the polymer is arranged, when the tab is welded, mutual electric connection between the first conductor layer 2 and the second conductor layer 3 can be achieved without penetrating through the support body layer 1, and then current generated on the first conductor layer 2 and the second conductor layer 3 is led out, and the problem of tab welding and conductor layer conduction of a composite current collector in the prior art is solved.

The polymer material used for the support layer 1 is specifically one or more of PET, PP, PE, PI, and polyarylsulfone, or other light-weight and strong insulating materials may be used instead. Preferably, the thickness of the support layer 1 is between 2 and 6 microns.

The first conductor layer 2 and the second conductor layer 3 may be made of aluminum, copper, nickel, silver, gold, carbon, stainless steel, or an alloy thereof. Preferably, the first conductor layer 2 and the second conductor layer 3 used as the positive electrode current collector are generally made of aluminum or an aluminum alloy material, and the first conductor layer 2 and the second conductor layer 3 used as the negative electrode current collector are generally made of copper or a copper alloy material.

Wherein the thickness of the first conductor layer 2 and the second conductor layer 3 is 0.2-5 microns. If the thicknesses of the first conductor layer 2 and the second conductor layer 3 are less than 0.2 micrometer, the electric conduction capability is insufficient, and the internal resistance is large; if the thickness exceeds 5 μm, the thickness and weight become excessive, affecting the energy density of the battery.

Next, in the present application, the area of the soldering region 4 accounts for 0.5 to 30% of the area of the first conductor layer 2 (or the second conductor layer 3). If the area ratio of the soldering region 4 exceeds 30%, the first conductive layer 2 and the second conductive layer 3 do not have a sufficient supporting area (provided by the support layer 1) and are easily damaged. If the area ratio of the welding region is less than 0.5%, a sufficient area cannot be provided for welding the tab.

The welding area 4 may be embodied in various shapes such as a rectangle, a circle, an ellipse, a fan, a polygon, or an irregular figure, which is not limited to the present application. The welding zone 4 can also be placed anywhere on the composite current collector, but is preferably placed at the edge of the composite current collector, which facilitates the subsequent welding of the tabs.

Specifically, as shown in fig. 1-2, according to the most preferred embodiment of the present application, the soldering region 4 is formed by making the lengths of the first conductor layer 2 and the second conductor layer 3 longer than the length of the support layer 4, so that when the first conductor layer 2 and the second conductor layer 3 are combined on both sides of the support layer 4, the soldering region 4 is naturally formed at the edge of the combined current collector, and no additional operation is required for the support layer 4.

Fig. 3 shows a specific structure of the composite current collector in the second embodiment of the present application. As shown in fig. 3, the soldering region 4 can also be formed by hollowing out the support layer.

Fig. 4 shows a specific structure of the composite current collector in the third embodiment of the present application. Fig. 4 is based on fig. 1, and the thickness of the first conductor layer 2 and/or the second conductor layer 3 in the soldering region 4 is made larger than the remaining portion thereof, so as to form a thickened region. Specifically, on the first conductor layer 1, the thickness of the thickened region in the soldering region 4 is h2, and the thickness of the remaining portion is h1, h2> h 1. By the arrangement, the strength of the welding area 4 can be enhanced, and damage in the machining process can be avoided; the thickness of the first conductor layer 2 and the second conductor layer 3 can be increased, and the welding strength can be improved.

Fig. 5 shows a specific structure of a composite current collector in a fourth embodiment of the present application. Fig. 5 is based on fig. 4, the edge of the thickened area is wider than the soldering area 4, and the width is 0.5-10mm, so that the edge of the thickened area overlaps with the edge of the support layer 1, the strength of the soldering area 4 is further enhanced, and the situation that the conductor layer is broken at the edge of the soldering area 4 is avoided.

Fig. 6 shows a specific structure of a composite current collector in a fifth embodiment of the present application. Fig. 6 is based on fig. 4, and conductive adhesive 5 is filled between first conductor layer 2 and second conductor layer 3 in welding area 4, and the bonding through conductive adhesive 5 can improve the strength of welding area 4, avoid damaging, also can promote the strength of first conductor layer 2 and second conductor layer 3 after welding.

In the above technical solution, the method for preparing the composite current collector may include the following steps: and pressing the conductor layer material into a conductor layer, and compounding the conductor layer and the support layer material. The conductor layer and the supporting layer can be connected and compounded through an adhesive. The conductor layer on which the recombination is completed can be thinned by chemical or electrochemical methods.

In contrast, if the thickened region is to be formed on the composite current collector, it is only necessary to provide a shield on the surface of the conductor layer above the bonding region to prevent corrosion of the conductor layer above the bonding region. The shield may be an adhesive tape that needs to be removed after thinning is completed.

In the above technical solution, the composite current collector may be used to manufacture a pole piece: coating a positive active material on the surface of a current collector to prepare a positive pole piece; and coating a negative active material on the surface of the current collector to obtain a negative pole piece. And assembling the positive pole piece, the diaphragm and the negative pole piece in a winding manner to form the dry cell. And (3) putting the dry cell into a cell shell, injecting electrolyte, and charging to form the secondary cell.

The present application will be described below with reference to examples, but the present application is not limited to these examples.

[ example 1 ]

And rolling the aluminum material with the purity of 99.7% to obtain the 5-micron aluminum foil. And compounding the 5-micron aluminum foil on two sides of the 5-micron PET through an adhesive to form a positive current collector. Wherein the PET has a molecular weight of 192.17, the adhesive is WB888 adhesive produced by Wuxi Yuke, the compounding temperature is 95 ℃, the compounding pressure is 0.5 MPa, and the standing time after compounding is 150 hours. The width of the 5-micron aluminum foil is 100mm, and the width of the PET is 80 mm. The area ratio of the welded region was 20%.

Chemical corrosion is carried out by adopting 20 percent NaOH solution, the temperature is 45 ℃, the corrosion time is 1 minute, and then deionized water is used for washing and drying. The thickness of the single-side aluminum layer is 3 microns after chemical etching.

[ example 2 ]

Example 2 differs from example 1 in that 4 micron PET material was used as the support layer and 3 micron aluminum foil as the conductor layer; the width of the aluminum foil is 100mm, the width of the PET is 90mm, and the area percentage of the welding area is 10%.

When the chemical corrosion thinning is carried out by adopting 20% NaOH solution, the surface of the conductor layer on the welding area is covered with an adhesive tape to form a thickened area, and the width of the thickened area is 1mm wider than that of the welding area. After the aluminum foil is thinned, the thickness of the thickened area is 3 microns, and the thickness of the residual area is 2 microns.

[ example 3 ]

Example 3 differs from example 1 in that 3 micron PP material was used as the support layer, 5 micron aluminum foil as the conductor layer; the width of the aluminum foil is 100mm, the width of the PET is 95mm, and the area percentage of the welding area is 5%.

And when the conductor layer is subjected to chemical corrosion thinning by adopting a 20% NaOH solution, covering an adhesive tape on the surface of the conductor layer on the welding area to form a thickened area. After the aluminum foil is thinned, the thickness of the thickened area is 5 microns, and the thickness of the residual area is 2 microns.

[ example 4 ]

Example 4 differs from example 1 in that 2 micron PE material was used as the support layer, 10 micron aluminum foil as the conductor layer; the width of the aluminum foil is 100mm, the width of the PET is 70mm, and the area percentage of the welding area is 30%.

And when the conductor layer is subjected to chemical corrosion thinning by adopting a 20% NaOH solution, covering an adhesive tape on the surface of the conductor layer on the welding area to form a thickened area. After the aluminum foil is thinned, the thickness of the thickened area is 10 microns, and the thickness of the residual area is 5 microns. In addition, conductive paste is filled in the bonding region.

[ example 5 ]

Example 5 differs from example 1 in that 6 microns of PI material was used as the support layer, 2 microns of aluminum foil as the conductor layer; the width of the aluminum foil is 100mm, the width of the PET is 75mm, and the area ratio of the welding area is 25%.

And when the conductor layer is subjected to chemical corrosion thinning by adopting a 20% NaOH solution, covering an adhesive tape on the surface of the conductor layer on the welding area to form a thickened area. After the aluminum foil is thinned, the thickness of the thickened area is 2 microns, and the thickness of the rest area is 0.5 micron. In addition, conductive paste is filled in the bonding region.

[ example 6 ]

Copper with a purity of 99.7% was subjected to rolling processing to obtain a 5 μm copper foil. And compounding the 5-micron copper foil on two sides of the 5-micron PET through an adhesive to form a positive current collector. Wherein the PET has a molecular weight of 192.17, the adhesive is WB888 adhesive produced by Wuxi Yuke, the compounding temperature is 95 ℃, the compounding pressure is 0.5 MPa, and the standing time after compounding is 150 hours. The width of the 4-micron copper foil is 100mm, the width of the PET is 80mm, and the area percentage of the welding area is 20%.

Chemical corrosion is carried out by adopting 20 percent NaOH solution, the temperature is 45 ℃, the corrosion time is 1 minute, and then deionized water is used for washing and drying. The thickness of the single-sided copper foil is 4 microns after chemical etching.

[ example 7 ]

The difference between example 7 and example 6 is that 4 micron PP material was used as the support layer, 6 micron copper foil as the conductor layer; the width of the copper foil is 100mm, the width of the PET is 90mm, and the area percentage of a welding area is 10%; the thickness of the thinned single-sided copper foil was 5 μm.

[ example 8 ]

Example 8 differs from example 6 in that 3 micron PET material was used as the support layer, 3 micron copper foil as the conductor layer; the width of the copper foil is 100mm, the width of the PET is 99mm, and the area of the welding area accounts for 1 percent

When the chemical corrosion thinning is carried out by adopting 20% NaOH solution, the surface of the conductor layer on the welding area is covered with an adhesive tape to form a thickened area, and the width of the thickened area is 0.5mm wider than that of the welding area. After the aluminum foil is thinned, the thickness of the thickened area is 3 microns, and the thickness of the residual area is 1 micron.

[ example 9 ]

Example 9 differs from example 6 in that 2 micron polyarylsulfone material was used as the support layer, 3 micron copper foil as the conductor layer; the width of the copper foil was 100mm, the width of the PET was 85mm, and the area ratio of the welded region was 15%.

And when the conductor layer is subjected to chemical corrosion thinning by adopting a 20% NaOH solution, covering an adhesive tape on the surface of the conductor layer on the welding area to form a thickened area. After the aluminum foil is thinned, the thickness of the thickened area is 3 microns, and the thickness of the residual area is 0.5 micron. In addition, conductive paste is filled in the bonding region.

[ example 10 ]

Example 10 differs from example 6 in that 5 micron PE material was used as the support layer, 6 micron copper foil as the conductor layer; the width of the copper foil is 100mm, the width of the PET is 70mm, and the area ratio of the welding area is 30%.

And when the conductor layer is subjected to chemical corrosion thinning by adopting a 20% NaOH solution, covering an adhesive tape on the surface of the conductor layer on the welding area to form a thickened area. After the aluminum foil is thinned, the thickness of the thickened area is 6 microns, and the thickness of the residual area is 2 microns. In addition, conductive paste is filled in the bonding region.

Comparative example 1

The difference between comparative example 1 and example 1 is that the width of the aluminum foil corresponds to the width of the PET, with no welded area.

Comparative example 2

The difference between comparative example 2 and example 1 is that 4 micron PP material was used as the support layer and the thickness of the aluminum foil was reduced to 1.5 micron.

Comparative example 3

The difference between comparative example 3 and example 6 is that the width of the copper foil is identical to the width of the PET, with no soldering area.

Comparative example 4

The difference between comparative example 4 and example 6 is that 4 microns of PE material was used as the support layer and the copper foil was thinned to 1 micron.

In order to illustrate the technical cooling of the technical solution of the present application, 300 current collectors in the above examples and comparative examples were prepared, and then the tab was welded, and the welding success rate was calculated. Meanwhile, the finished current collector is subjected to a tensile strength test, and the test method adopts the test standard of the tensile strength of the metal foil material recorded in HB 5280-. The test results are shown in table 1.

TABLE 1

As shown in table 1, it is understood from comparative example 1 and comparative example 2, and example 6 and comparative example 3 that the welding success rate of the tab can be greatly improved and the tensile strength of the welded current collector can be ensured by providing the welding region without the polymer. Meanwhile, the thickness of the conductor layer is also one of the factors influencing the tab welding and the tensile strength of the current collector, but the influence of the too thin conductor layer can be overcome by technical means of setting a thickening area, expanding the range of the thickening area or filling conductive adhesive and the like, and the success rate of tab welding and the tensile strength of the current collector are further improved.

Next, the current collectors obtained in the above examples 1 to 10 and comparative examples 1 to 4 were fabricated into batteries, and the vibration test failure ratio and 300 cycle failure ratio, the combination of the current collectors, and the test results are shown in table 2. Wherein, the failure proportion of the vibration test is obtained by adopting the 7.3 vibration test in the national standard 31241-2014; the 300 cycle failure rate is obtained by the following method: the 1C/1C charge/discharge test was performed at a temperature of 25C and the proportion of dead cells with no voltage output over 300 cycles was recorded.

TABLE 2

	Positive current collector	Negative current collector	Failure ratio of vibration test	300 cycle failure rate
					Example 11	Example 1	Example 6	10％	3％
Example 12	Example 2	Example 7	0％	0％
					Example 13	Example 3	Example 8	0％	0％
Example 14	Example 4	Example 9	0％	0％
					Example 15	Example 5	Example 10	0％	0％
Example 16	Example 1	Example 8	2％	0％
					Comparative example 5	Example 1	Comparative example 3	75％	13％
Comparative example 6	Example 1	Comparative example 4	100％	25％
					Comparative example 7	Comparative example 1	Example 6	75％	11％
Comparative example 8	Comparative example 2	Example 6	100％	19％

As shown in table 2, the failure rate of vibration test and the failure rate of 300 cycles of batteries (comparative examples 5 to 8) made of the existing composite current collector are significantly higher than those of batteries (examples 11 to 16) made of the composite current collector described in the present application, which indicates that the composite current collector described in the present application can greatly improve the safety performance and the service life of the secondary battery when applied to the secondary battery.

Although the illustrative embodiments of the present application have been described above to enable those skilled in the art to understand the present application, the present application is not limited to the scope of the embodiments, and various modifications within the spirit and scope of the present application defined and determined by the appended claims will be apparent to those skilled in the art from this disclosure.

Claims (15)

1. A composite current collector, comprising:

a support layer made of a polymer;

a first conductor layer disposed on one side of the support layer;

a second conductor layer disposed on the other side of the support layer;

a welding area;

wherein the first conductor layer and the second conductor layer are free of the polymer in the bonding region.

2. The composite current collector of claim 1, wherein the support layer is made of one of PET, PP, PE, PI, polyarylsulfone.

3. The composite current collector of claim 1, wherein the first and second conductor layers are made of aluminum, copper, nickel, silver, gold, carbon, stainless steel.

4. The composite current collector of claim 1, wherein the first and second conductor layers have a thickness of 0.2-5 microns.

5. The composite current collector of claim 1, wherein the area of the soldering region is 0.5-30% of the area of the first conductor layer.

6. The composite current collector of claim 1, wherein the shape of the welded area is circular, elliptical, fan-shaped, polygonal.

7. The composite current collector of claim 1, wherein the weld region is located at an edge of the composite current collector.

8. The composite current collector of claim 1, wherein the weld area is formed by the first conductor layer and the second conductor layer having a length longer than the support layer.

9. The composite current collector of claim 1, wherein the welded region is openly formed by the support layer.

10. The composite current collector of claim 1, wherein a conductive glue is provided between said first conductor layer and said second conductor layer in said weld area.

11. The composite current collector of claim 1, wherein said first conductor layer and/or said second conductor layer has a greater thickness than the remainder thereof in said weld region, forming a thickened region.

12. The composite current collector of claim 11, wherein the edge of said thickened area is wider than said welding area by 0.5-10 mm.

13. A battery is characterized by comprising a positive pole piece, a negative pole piece, a diaphragm and an electrolyte, wherein,

the positive and/or negative electrode sheet comprises a current collector of any one of claims 1-12.

14. An object, characterized in that the object comprises a battery according to claim 13.

15. An object according to claim 14, wherein the object is an electronic product or an electric vehicle.

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