WO2022022337A1

WO2022022337A1 - Bipolar current collector and secondary battery

Info

Publication number: WO2022022337A1
Application number: PCT/CN2021/107413
Authority: WO
Inventors: 张芹
Original assignee: 厦门海辰新能源科技有限公司
Priority date: 2020-07-28
Filing date: 2021-07-20
Publication date: 2022-02-03

Abstract

A bipolar current collector and a secondary battery. The bipolar current collector (10) comprises a positive electrode conductive layer; a negative electrode conductive layer; and an insulating layer. The positive electrode conductive layer comprises a positive electrode partitioning region and a positive electrode region, the negative electrode conductive layer comprises a negative electrode partitioning region and a negative electrode region, and at least a portion of at least one of the positive electrode partitioning region and the negative electrode partitioning region is removed.

Description

A bipolar current collector and secondary battery

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on the Chinese patent applications with application numbers 202010742626.5 and 202021525174.7, and the filing date is July 28, 2020, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is incorporated herein by reference.

technical field

The present application relates to the technical field of secondary batteries, and in particular, to a bipolar current collector and a secondary battery.

Background technique

In the composite current collector, the negative electrode current collector usually forms a copper metal layer on both sides of the polymer layer, and the positive electrode current collector usually forms an aluminum metal layer on both sides of the polymer layer, and then prepares the pole piece and the secondary battery.

In order to further improve the energy density of the battery, the prior art provides a bipolar current collector, in which a copper layer and an aluminum layer are respectively formed on the two surfaces of the polymer insulating layer, and then the copper layer is used as a negative electrode, and the aluminum layer is used as a positive electrode for polarizing. Preparation of sheets and secondary batteries.

In order to improve the production efficiency of the battery, the aluminum layer and the copper layer are usually coated on the polymer insulating layer with a wide width first, and then they are cut to prepare the pole piece. However, there is a certain degree of short circuit problem in the secondary battery prepared after the bipolar current collector is slit.

SUMMARY OF THE INVENTION

The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a bipolar current collector, which can reduce the short circuit problem of the positive and negative electrodes of the bipolar current collector after cutting to a certain extent, and reduce the secondary battery prepared by the bipolar current collector. short circuit problem.

The present application also proposes a secondary battery having the bipolar current collector.

In order to achieve the above purpose, according to an embodiment of the first aspect of the present application, a bipolar current collector is proposed. The bipolar current collector includes: a positive electrode conductive layer; a negative electrode conductive layer; and an insulating layer, and the insulating layer is located in the Between the positive electrode conductive layer and the negative electrode conductive layer, the side surface of the positive electrode conductive layer away from the insulating layer includes at least one positive electrode slitting area and at least two positive electrode electrode areas, and the positive electrode slitting area is located in the phase. Between two adjacent positive electrode regions, the side surface of the negative conductive layer away from the insulating layer includes at least one negative electrode cutting region and at least two negative electrode electrode regions, and the negative electrode cutting regions are located in two adjacent ones. Between each of the negative electrode regions, at least a part of at least one of the positive electrode conductive layer in the positive electrode slitting region and the negative electrode conductive layer in the negative electrode slitting region is removed.

According to the bipolar current collector of the embodiments of the present application, the problem of short circuit between the positive and negative electrodes of the bipolar current collector after being cut, and the short circuit problem of the secondary battery prepared by the bipolar current collector can be reduced to a certain extent.

In addition, the bipolar current collector according to the above embodiments of the present application may also have the following additional technical features:

According to an embodiment of the present application, the positive electrode conductive layer in the positive electrode slitting area is completely removed, and/or the negative electrode conductive layer in the negative electrode slitting area is completely removed.

According to an embodiment of the present application, the thickness of the positive electrode conductive layer in the positive electrode cutting area is 1-500 nm, and/or the thickness of the negative electrode conductive layer in the negative electrode cutting area is 1-1000 nm .

According to an embodiment of the present application, the maximum thickness of the positive electrode conductive layer is 20-1500 nm, and the maximum thickness of the negative electrode conductive layer is 30-2500 nm.

According to an embodiment of the present application, the thickness of the insulating layer is 1.2-20 μm.

According to an embodiment of the present application, in the thickness direction of the insulating layer, the projection of the anode split region falls into the projection of the anode split region.

According to an embodiment of the present application, the width of the positive electrode cutting region is greater than the width of the negative electrode cutting region.

According to an embodiment of the present application, the difference in width between the positive electrode slitting area and the negative electrode slitting area is 1-5 mm.

According to an embodiment of the present application, there are multiple positive electrode cutting regions and are arranged at intervals, and there are multiple negative electrode cutting regions and are arranged at intervals.

According to an embodiment of the second aspect of the present application, a secondary battery is provided, and the secondary battery includes the bipolar current collector according to the embodiment of the first aspect of the present application.

The combination cooker according to the embodiment of the present application has advantages such as good electrical performance by using the bipolar current collector according to the embodiment of the first aspect of the present application.

Additional aspects and advantages of the present application will be set forth, in part, from the following description, and in part will become apparent from the following description, or may be learned by practice of the present application.

Description of drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily understood from the following description of embodiments in conjunction with the accompanying drawings, wherein:

1 is a schematic diagram of a first structure of a bipolar current collector provided in an embodiment of the present application;

2 is a schematic structural diagram of a split region in a bipolar current collector provided in an embodiment of the present application;

Fig. 3 is the second structural schematic diagram of the bipolar current collector provided by the embodiment of the present application;

FIG. 4 is a third structural schematic diagram of a bipolar current collector provided by an embodiment of the present application;

FIG. 5 is a schematic plan view of a bipolar current collector provided in an embodiment of the present application.

Icons: 10 - bipolar current collector; 110 - electrode area; 120 - cutting area; 111 - first polymer insulating layer; 112 - first positive electrode metal layer; 113 - first negative electrode metal layer; 121 - second Polymer insulating layer; 122 - the second positive metal layer; 123 - the second negative metal layer.

detailed description

The following describes in detail the embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, but should not be construed as a limitation on the present application.

In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " Rear, Left, Right, Vertical, Horizontal, Top, Bottom, Inner, Outer, Clockwise, Counterclockwise, Axial, The orientations or positional relationships indicated by "radial direction", "circumferential direction", etc. are based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying the indicated devices or elements. It must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as a limitation of the present application. Furthermore, features delimited with "first", "second" may expressly or implicitly include one or more of that feature. In the description of this application, unless stated otherwise, "plurality" means two or more.

In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood in specific situations.

The bipolar current collector 10 according to the embodiment of the present application will be described below with reference to the accompanying drawings.

As shown in FIGS. 1-5 , the bipolar current collector 10 according to the embodiment of the present application includes a positive electrode conductive layer, a negative electrode conductive layer and an insulating layer.

The insulating layer is located between the positive electrode conductive layer and the negative electrode conductive layer, and the side surface of the positive electrode conductive layer away from the insulating layer includes at least one positive electrode cutting area and at least two positive electrode electrode areas. The positive electrode cutting area is located between two adjacent positive electrode electrode areas, and the side surface of the negative electrode conductive layer away from the insulating layer includes at least one negative electrode cutting area and at least two negative electrode electrode areas, and the negative electrode dividing area is A cut area is located between two adjacent negative electrode areas, and at least a part of at least one of the positive electrode conductive layer in the positive electrode cut area and the negative electrode conductive layer in the negative electrode cut area is remove.

After extensive research, the inventor found that due to the burrs generated during the slitting process, the burrs may cause contact between the positive electrode conductive layer and the negative electrode conductive layer, thereby causing the problem of short circuit between the positive electrode and the negative electrode.

According to the bipolar current collector 10 of the embodiment of the present application, at least a part of at least one of the positive electrode conductive layer in the positive electrode cutting region and the negative electrode conductive layer in the negative electrode cutting region is removed . If the amount of the conductive layer in the slitting area is reduced, when the bipolar current collector 10 is slitted through the slitting area, the amount of metal burrs generated in the slitting area is reduced, or even not, to a certain extent. Avoid contact between the positive electrode metal layer and the negative electrode metal layer at the slit, thereby reducing the occurrence of short circuit between the positive and negative electrodes.

Therefore, the bipolar current collector 10 according to the embodiment of the present application can reduce the short circuit problem of the positive and negative electrodes of the bipolar current collector after cutting to a certain extent, and reduce the short circuit problem of the secondary battery prepared therefrom.

The bipolar current collector 10 according to the specific embodiment of the present application is described below with reference to the accompanying drawings.

In some specific embodiments of the present application, as shown in FIGS. 1-5 , the bipolar current collector 10 according to the embodiments of the present application includes a positive electrode conductive layer, a negative electrode conductive layer and an insulating layer

Optionally, the positive electrode conductive layer in the positive electrode slitting area is completely removed, and/or the negative electrode conductive layer in the negative electrode slitting area is completely removed. If the positive metal layer and the negative metal layer are not provided in the slitting area, there is no metal burr problem when slitting in the slitting area, which can effectively avoid the problem of short circuit of positive and negative electrodes during slitting.

Advantageously, the thickness of the positive electrode conductive layer in the positive electrode slitting area is 1-500 nm, and/or the thickness of the negative electrode conductive layer in the negative electrode slitting area is 1-1000 nm. The maximum thickness of the positive electrode conductive layer is 20-1500 nm, and the maximum thickness of the negative electrode conductive layer is 30-2500 nm. The current conductivity of the positive electrode conductive layer in the positive electrode slitting area and the negative electrode conductive layer in the negative electrode slitting area is good, which can satisfy the current flow capacity of the metal layer below the active material layer; After the positive electrode conductive layer in the positive electrode slitting area and the negative electrode conductive layer in the negative electrode slitting area are cut, the amount of metal burrs generated is very small, so as to avoid short circuit of positive and negative electrodes during cutting; The difference in tensile properties between the slitting area and the electrode area is small, so as to avoid the problem of wrinkling of the current collector when passing the roller.

The thickness of the insulating layer is 1.2-20 μm. At the slitting area, both surfaces of the insulating layer are provided with metal layers. On the one hand, the difference in tensile properties between the electrode area and the slitting area can be made small, so that the bipolar current collector 10 can be prevented from being rolled over. wrinkled. On the other hand, the thickness of the metal layer in the slitting area is smaller than that in the electrode area, which can reduce the amount of metal burrs during slitting, and limit the thickness of the insulating layer, which can effectively avoid metal burrs on both surfaces. Over the polymer insulating layer, so as to avoid the contact between the metal burrs on the two surfaces, so as to avoid the short circuit of the positive and negative electrodes during cutting.

In the thickness direction of the insulating layer, the projection of the negative electrode cutting region falls into the projection of the positive electrode cutting region.

The width of the positive electrode slitting area is greater than the width of the negative electrode slitting area. The width of the negative electrode active material layer is larger than the width of the positive electrode active material layer, so that more lithium ions passing through the separator can be embedded in the negative electrode active material layer, thereby improving the electrical performance of the battery.

The difference in width between the positive electrode slitting area and the negative electrode slitting area is 1-5 mm. It can be ensured that the lithium ions passing through the separator can basically be embedded in the negative electrode active material layer, and the waste of the negative electrode active material can be avoided.

There are a plurality of the positive electrode cutting regions and are arranged at intervals, and the plurality of the negative electrode separation regions are arranged at intervals.

In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

FIG. 1 is a schematic diagram of a first structure of a bipolar current collector 10 provided by an embodiment of the present application. Referring to FIG. 1 , in the embodiment of the present application, along the width direction of the bipolar current collector 10 , the bipolar current collector 10 includes at least two electrode regions 110 and at least one cutting region 120 that are connected to each other, and two adjacent electrode regions 120 are connected to each other. A cutting area 120 is provided between the electrode areas 110 . As shown in FIG. 1 , the bipolar current collector 10 includes two electrode regions 110 and one slitting region 120 . In other embodiments, the bipolar current collector 10 may further include three electrode regions 110 and two cutting regions 120, or four electrode regions 110 and three cutting regions 120, which are not limited in the embodiments of the present application. As long as two adjacent electrode regions 110 are connected by the dividing region 120 .

FIG. 2 is a schematic structural diagram of the splitting region 120 in the bipolar current collector 10 provided by the embodiment of the present application. Please refer to FIG. 1 and FIG. 2 together. In the embodiment of the present application, the electrode region 110 includes a first polymer insulating layer 111 , a first positive electrode metal layer 112 and a first negative electrode metal layer 113 . A negative metal layer 113 is respectively disposed on two surfaces of the first polymer insulating layer 111 . The cutting area 120 includes a second polymer insulating layer 121 , a second positive electrode metal layer 122 and a second negative electrode metal layer 123 , and the second positive electrode metal layer 122 and the second negative electrode metal layer 123 are respectively disposed on the second polymer insulating layer 121 of the two surfaces.

Please continue to refer to FIG. 1 and FIG. 2 , the first polymer insulating layer 111 and the second polymer insulating layer 121 are integrally formed, the thicknesses of the first polymer insulating layer 111 and the second polymer insulating layer 121 are the same, and the first high The upper surface of the molecular insulating layer 111 is flush with the upper surface of the second polymer insulating layer 121 , and the lower surface of the first polymer insulating layer 111 is flush with the lower surface of the second polymer insulating layer 121 . The first positive metal layer 112 and the second positive metal layer 122 are both located on one side of the polymer insulating layer, and the first negative metal layer 113 and the second negative metal layer 123 are both located on the other side of the polymer insulating layer. For example, the first positive metal layer 112 is located on the upper surface of the first polymer insulating layer 111, the second positive metal layer 122 is located on the upper surface of the second polymer insulating layer 121, and the first negative metal layer 113 is located on the first polymer insulating layer 121. On the lower surface of the layer 111 , the second negative metal layer 123 is located on the lower surface of the second polymer insulating layer 121 .

The polymer insulating layer (the first polymer insulating layer 111 and the second polymer insulating layer 121 ) is non-conductive, and the material of the polymer insulating layer can be polystyrene, polypropylene, polyester, polycarbonate, Teflon or polyimide film. This application is not limited, as long as it is a polymer insulating layer and can insulate the positive electrode metal layer and the negative electrode metal layer.

Optionally, the positive metal layers (the first positive metal layer 112 and the second positive metal layer 122 ) are metal aluminum layers, and the negative metal layers (the first negative metal layer 113 and the second negative metal layer 123 ) are metal copper layers or Metallic nickel layer. In the embodiments of the present application, the positive electrode metal layer is a metal aluminum layer to conduct the current conduction of the positive electrode; the negative electrode metal layer is a metal copper layer to conduct the current conduction of the negative electrode. In this application, the positive metal layer is not limited to a metal aluminum layer, as long as the positive metal layer that can be used as a current collector is within the protection scope of this application; the negative metal layer is not limited to a metal copper layer, as long as it can be used as a current collector. The metal layer of the negative electrode is all within the protection scope of the present application.

After extensive research, the inventor found that metal burrs are generated during the cutting process, and the metal burrs may cause the positive electrode metal layer and the negative electrode metal layer to contact, thereby causing the problem of short circuit between the positive electrode and the negative electrode. In this embodiment of the present application, at least one of the second positive electrode metal layer 122 and the second negative electrode metal layer 123 is completely or partially removed. When the amount of the metal layer in the slitting area 120 is reduced, when the bipolar current collector 10 is slitted by the slitting area 120, the amount of metal burrs generated in the slitting area 120 is reduced, or even none, which can be To a certain extent, the contact between the positive electrode metal layer and the negative electrode metal layer at the slit is avoided, thereby reducing the occurrence of short circuit between the positive electrode and the negative electrode.

In the embodiment of the present application, the thickness of the first positive electrode metal layer 112 is a, and the thickness of the first negative electrode metal layer 113 is b. The thickness of the second positive electrode metal layer 122 is c, and the thickness of the second negative electrode metal layer 123 is d. Among them, 0≤c+d<a+b.

As shown in FIG. 1 and FIG. 2 , the dotted line in the figure is the cutting line of the cutting area 120. Since the sum of the thicknesses of the metal layers in the cutting area 120 (the sum of the thicknesses of the second positive metal layer 122 and the second negative metal layer 123) ) is less than the sum of the thicknesses of the metal layers in the electrode region 110 (the sum of the thicknesses of the first positive electrode metal layer 112 and the first negative electrode metal layer 113 ), then when the current collector is cut at the dotted line, the cutting region 120 produces The amount of metal burrs is reduced, or even none, which can effectively avoid the contact between the positive electrode metal layer and the negative electrode metal layer at the slit, thereby avoiding the short circuit of the positive and negative electrodes.

In order to form the structure of the bipolar current collector 10, a positive electrode metal layer is first deposited on a surface of the polymer insulating layer, and the slitting area 120 is masked during deposition, so that the slitting area 120 forms a thinner positive metal layer; then A negative electrode metal layer is deposited on the other surface of the polymer insulating layer, and the slitting area 120 is also masked during deposition, so that the slitting area 120 forms a thinner negative electrode metal layer.

For example: when depositing the metal layer, a baffle is arranged between the second polymer insulating layer 121 and the metal source, the baffle includes a shielding part and a hollow part, and the hollow part of the baffle at the position corresponding to the electrode region 110 occupies an area of The ratio is greater than the proportion of the hollow portion of the baffle at the position corresponding to the cutting area 120 , so as to form the structure of the bipolar current collector 10 shown in FIG. 1 . In other embodiments, a baffle plate with a certain porosity may be arranged in the electrode region 110 without a baffle plate, so as to form the bipolar current collector 10 in FIG. 1 .

Optionally, the thickness of the polymer insulating layer is 1.2-20 μm, the relationship between the thicknesses of the first positive metal layer 112 and the second positive metal layer 122 is: 0<c<a, and the thickness difference ac between the two is 10-1000nm . The relationship between the thicknesses of the second negative electrode metal layer 123 and the first negative electrode metal layer 113 is: 0<d<b, and the thickness difference b-d between the two is 10-1000 nm. Optionally, the thickness of the polymer insulating layer is 2-12 μm.

At the slitting area 120, both surfaces of the second polymer insulating layer 121 are provided with metal layers. The polar current collector 10 is wrinkled as it passes over the roll. On the other hand, the thickness of the metal layer of the slitting area 120 is smaller than that of the electrode area 110, which can reduce the amount of metal burrs during slitting, and limit the thickness of the second polymer insulating layer 121, which can effectively avoid The metal burrs on the two surfaces pass through the polymer insulating layer, so as to avoid the contact between the metal burrs on the two surfaces, and avoid short circuit of positive and negative electrodes during cutting.

The thickness c of the second positive metal layer 122 is 1-500 nm, the thickness a of the first positive metal layer 112 is 20-1500 nm; the thickness d of the second negative metal layer 123 is 1-1000 nm, the thickness of the first negative metal layer 113 b is 30-2500 nm.

The conductivity of the first positive electrode metal layer 112 and the first negative electrode metal layer 113 is good, which can satisfy the current flow capacity of the metal layer below the active material layer; the second positive electrode metal layer 122 and the second negative electrode metal layer 123 After cutting, the amount of metal burrs generated is very small, so as to avoid short circuit of positive and negative electrodes during cutting; and the difference in tensile properties between the cutting area 120 and the electrode area 110 can be made small, so as to avoid the current collector hitting when the roller is passed. wrinkle problem.

In some possible embodiments, the thickness of the polymer insulating layer (the first polymer insulating layer 111 and the second polymer insulating layer 121 ) is 10 μm, the thickness a of the first positive electrode metal layer 112 is 1000 nm, and the first negative electrode metal layer 112 has a thickness of 1000 nm. The thickness b of the layer 113 is 2000 nm, the thickness c of the second positive electrode metal layer 122 is 400 nm, and the thickness d of the second negative electrode metal layer 123 is 800 nm. This application is not limited.

In the embodiment of the present application, the thickness difference between the first positive metal layer 112 and the second positive metal layer 122 is a-c, and the thickness difference between the second negative metal layer 123 and the first negative metal layer 113 is b-d. The values of a-c and the values of b-d may be consistent or inconsistent, which are not limited in this application.

Please continue to refer to FIG. 2 , in the embodiment of the present application, along the width direction of the bipolar current collector 10 , the width of the second anode metal layer 123 is smaller than the width of the second anode metal layer 122 , and the second anode metal layer 122 is in the Both sides of the projection of the thickness direction of the bipolar current collector 10 are beyond both sides of the width direction of the second negative electrode metal layer 123 .

As shown in FIG. 2 , after the projection of the second positive electrode metal layer 122 , its width is larger than the width of the second negative electrode metal layer 123 by a width of e+f, and a part of the excess part is on the left, such as e, and a part is on the right, such as f After the positive electrode active material layer is coated on the first positive electrode metal layer 112 and the negative electrode active material layer is coated on the first negative electrode metal layer 113, the width of the negative electrode active material layer is larger than the width of the positive electrode active material layer, which can make Lithium ions passing through the separator can be more intercalated into the anode active material layer, thereby improving the electrical performance of the battery.

Optionally, the width difference between the second positive electrode metal layer 122 and the second negative electrode metal layer 123 is 1-5 mm. That is to say, the sum of e+f in FIG. 2 is between 1-5 mm, which can ensure that the lithium ions passing through the separator can basically be embedded in the negative electrode active material layer, and the waste of negative electrode active material can be avoided.

In some possible embodiments, the value of e+f is 1 mm, 2 mm, 3 mm, 4 mm or 5 mm. In the embodiments of the present application, the widths of e and f may be the same or different, which are not limited in the present application.

FIG. 3 is a schematic diagram of the second structure of the bipolar current collector 10 provided by the embodiment of the present application. Referring to FIG. 3 , the thickness of the second positive electrode metal layer 122 is 0, and the thickness of the second negative electrode metal layer 123 is 0. If the positive metal layer and the negative metal layer are not provided in the slitting area 120, there is no metal burr problem when the slitting area 120 is slit, which can effectively avoid the short circuit of the positive and negative electrodes during slitting.

In order to form the structure of the bipolar current collector 10, a positive electrode metal layer is first deposited on a surface of the polymer insulating layer, and the slitting area 120 is masked during deposition, and the positive electrode metal layer is not formed at the slitting area 120; A negative electrode metal layer is deposited on the other surface of the polymer insulating layer, and the cutting area 120 is also masked during deposition, and the negative electrode metal layer is not formed at the cutting area 120 . In other embodiments, the positive electrode metal layer may be entirely deposited on one surface, the negative electrode metal layer may be entirely deposited on the other surface, and then part of the positive electrode metal layer and the negative electrode metal layer may be washed off to form the slitting area 120, thereby obtaining the result shown in FIG. 3 . The bipolar current collector 10.

FIG. 4 is a schematic diagram of a third structure of the bipolar current collector 10 provided by the embodiment of the present application. Referring to FIG. 4 , the thickness of the second positive electrode metal layer 122 is 0, and the thickness d of the second negative electrode metal layer 123 is 0<d≤b. Or the thickness c of the second positive electrode metal layer 122 is 0<c≦a, and the thickness of the second negative electrode metal layer 123 is 0.

Only one surface of the slitting area 120 has a metal layer, and the other surface is not provided with a metal layer. Even if a metal burr is generated on one surface with a metal layer during slitting, since the other surface is not provided with a metal layer, it can be effectively avoided. The metal burr is in contact with the metal layer on the other surface, thus avoiding short circuit between positive and negative electrodes. Moreover, the provision of one metal layer can also reduce the difference in tensile properties between the electrode region 110 and the slitting region 120, thereby alleviating the problem of wrinkling of the bipolar current collector 10 over the roll, making the structure of the metal layer more compact. stability.

Optionally, the thickness c of the second anode metal layer 122 is 0, and the thickness d of the second anode metal layer 123 is the same as the thickness b of the first anode metal layer 113 . Then, after cutting from the dotted line in Figure 4, the active material layer is directly coated on the negative electrode metal layer to ensure that all lithium ions passing through the separator can be embedded in the negative electrode active material layer, and there is no need to specially form e in Figure 2. and the structure of f. Therefore, this structure has the following advantages: when cutting is performed at the dotted line in FIG. 4 , even though metal burrs are formed due to the second negative electrode metal layer 123 , the second positive electrode metal layer 122 is not provided on the back of the second negative electrode metal layer 123 . , therefore, the problem of short-circuiting the positive and negative electrodes due to the effect of metal burrs can be effectively avoided; the thickness of the second negative electrode metal layer 123 is consistent with the thickness of the first negative electrode metal layer 113, and when the bipolar current collector 10 is cut, The second negative electrode metal layer 123 contacts the roller surface for over-rolling, which can make the difference between the tensile properties of the electrode area 110 in contact with the roller and the slitting area 120 smaller, and avoid the bipolar current collector 10 from wrinkling during over-rolling; and After the second negative electrode metal layer 123 with the same thickness of the first negative electrode metal layer 113 is cut, the negative electrode active material layer can be directly coated, so that more lithium ions passing through the separator can be embedded in the negative electrode active material layer.

In order to form the structure of the bipolar current collector 10, a positive electrode metal layer is first deposited on a surface of the polymer insulating layer, and the slitting area 120 is masked during deposition, so that the slitting area 120 does not form a positive electrode metal layer; The other surface of the molecular insulating layer is entirely deposited with a negative electrode metal layer. In other embodiments, the positive electrode metal layer may be entirely deposited on one surface, the negative electrode metal layer may be entirely deposited on the other surface, and then part of the positive electrode metal layer may be washed off to form the slitting area 120 to obtain the bipolar collector in FIG. 4 . Fluid 10.

In other embodiments, FIG. 5 is a schematic plan view of the bipolar current collector 10 . Referring to FIG. 5 , along the length direction of the bipolar current collector 10 , the second positive metal layer 122 includes a plurality of second positive metal layers 122 , and the plurality of second positive metal layers 122 are arranged at intervals, and two ends of each second positive metal layer 122 are respectively connected The first positive metal layers 112 of two adjacent electrode regions 110 . The second negative metal layers 123 include a plurality of second negative metal layers 123 arranged at intervals, and two ends of each second negative metal layer 123 are respectively connected to the first negative metal layers 113 of two adjacent electrode regions 110 . The projection of the second positive electrode metal layer 122 in the thickness direction of the bipolar current collector 10 does not overlap with the second negative electrode metal layer 123 , and the projection of the second negative electrode metal layer 123 in the thickness direction of the bipolar current collector 10 does not overlap with the second negative electrode metal layer 123 . The positive metal layers 122 overlap.

The second negative electrode metal layer 123 is not formed on the back of the second positive metal layer 122 , and the second positive metal layer 122 is not formed on the back of the second negative metal layer 123 . When the current collector is cut, even if metal burrs are generated, the short circuit phenomenon caused by the contact between the positive electrode metal layer and the negative electrode metal layer can be avoided because the backside is not provided with a metal layer. In addition, the metal layers at the two adjacent electrode regions 110 may be connected by the metal layers arranged at intervals at the cutting region 120, and the tensile properties of the entire current collector may also be relatively uniform.

In other embodiments, FIG. 5 and FIG. 2 can be combined to reduce the possibility of contact between the positive electrode metal layer and the negative electrode metal layer after cutting from multiple dimensions, so as to avoid the phenomenon of short circuit between the positive and negative electrodes after the cutting produce.

The above bipolar current collector 10 can be used to prepare a pole piece, and the pole piece includes the bipolar current collector 10 , a positive electrode active material layer and a negative electrode active material layer. The positive electrode active material layer is disposed on the first positive electrode metal layer 112 . The negative electrode active material layer is provided on the first negative electrode metal layer 113 . The positive and negative electrode active materials may be coated first after being cut, or the active material layer may be coated before being cut, which is not limited in this application. However, both of them can avoid the problem of short circuit of positive and negative electrodes during the cutting process, thereby improving the performance of the battery.

The above-mentioned pole pieces are used to prepare a battery core, and the battery core includes a plurality of the above-mentioned pole pieces and a plurality of separators, a separator is arranged between two adjacent pole pieces, and a positive electrode active material layer and a negative electrode active material are respectively arranged on both sides of the separator. Floor. The battery cell can be used to prepare a secondary battery, and the secondary battery has better electrical properties.

The beneficial effects of the bipolar current collector 10, the pole piece and the secondary battery provided by the embodiments of the present application include:

(1) The structural arrangement of the slitting area 120 can avoid the problem of short circuit between the positive and negative electrodes caused by the metal burrs generated during the slitting.

(2) The problem of wrinkling of the bipolar current collector 10 when passing through the roll can be alleviated or even eliminated.

(3) More negative electrode active material layers can be formed at the negative electrode of the pole piece, so that there are enough areas to receive lithium ions, so that the lithium ions passing through the separator are more embedded in the negative electrode active material layer.

The above descriptions are only a part of the embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Other structures and operations of the combination cooktop according to the embodiment of the present application are known to those of ordinary skill in the art, and will not be described in detail here.

In the description of this specification, reference to the terms "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples," or the like, is meant to incorporate the embodiment. A particular feature, structure, material, or characteristic described by an example or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the present application, The scope of the application is defined by the claims and their equivalents.

Claims

A bipolar current collector comprising:

Positive conductive layer;

Negative conductive layer;

an insulating layer, the insulating layer is located between the positive electrode conductive layer and the negative electrode conductive layer, and the side surface of the positive electrode conductive layer away from the insulating layer includes at least one positive electrode cutting area and at least two positive electrode electrode areas , the positive electrode slitting area is located between two adjacent positive electrode electrode areas, and the side surface of the negative electrode conductive layer away from the insulating layer includes at least one negative electrode slitting area and at least two negative electrode electrode areas, so The negative electrode slitting area is located between two adjacent negative electrode electrode areas, and at least one of the positive electrode conductive layer in the positive electrode slitting area and the negative electrode conductive layer in the negative electrode slitting area is separated. At least a portion is removed.
The bipolar current collector of claim 1, wherein the positive electrode conductive layer in the positive electrode cutting region is completely removed, and/or

The negative electrode conductive layer in the negative electrode cutting area is completely removed.
The bipolar current collector according to claim 1, wherein the thickness of the positive electrode conductive layer in the positive electrode cutting area is 1-500 nm, and/or

The thickness of the negative electrode conductive layer in the negative electrode cutting area is 1-1000 nm.
The bipolar current collector according to claim 1, wherein the maximum thickness of the positive electrode conductive layer is 20-1500 nm, and the maximum thickness of the negative electrode conductive layer is 30-2500 nm.
The bipolar current collector of claim 1, wherein the insulating layer has a thickness of 1.2-20 μm.
The bipolar current collector according to claim 1 , wherein, in the thickness direction of the insulating layer, the projection of the anode split region falls into the projection of the anode split region.
The bipolar current collector of claim 1 , wherein the width of the positive electrode split region is greater than the width of the negative electrode split region.
The bipolar current collector according to claim 7, wherein the difference in width between the positive electrode slitting area and the negative electrode slitting area is 1-5 mm.
The bipolar current collector according to claim 1, wherein a plurality of the positive electrode cutting regions are arranged at intervals, and a plurality of the negative electrode separation regions are arranged at intervals.
A secondary battery comprising the bipolar current collector according to any one of claims 1-9.