CN220569712U - Current collecting unit, pole piece and battery - Google Patents

Abstract

The utility model provides a current collecting unit, a pole piece and a battery. Wherein, the current collecting unit includes: a substrate; the insulating layers are positioned on the side surfaces of the substrate in the thickness direction, the insulating layers comprise a plurality of insulating strips which are distributed at intervals in the width direction, and the thickness of the insulating strips is gradually decreased from inside to outside in the width direction. To reduce die cut burrs.

Description

Current collecting unit, pole piece and battery

Technical Field

The utility model relates to the technical field of current collecting units, pole pieces and batteries.

Background

A Battery (Battery) refers to a device that converts chemical energy into electrical energy in a cup, tank, or other container or portion of a composite container that contains electrolyte and electrodes to generate an electrical current. The performance parameters of the battery are mainly electromotive force, capacity, specific energy and resistance. The battery is used as an energy source, the current which has stable voltage, stable current, long-time stable power supply and little influence from the outside can be obtained, the battery has simple structure, convenient carrying, simple and easy charging and discharging operation, is not influenced by the outside climate and temperature, has stable and reliable performance, and plays a great role in various aspects in the life of the modern society.

In batteries, safety is one of the most important research subjects. Internal short circuits are the most common sources of safety problems such as fire or explosion, wherein the most heat is generated when short circuits are caused, and the most easy fire and explosion are caused when positive electrode current collectors are contacted with negative electrodes to generate short circuits. Therefore, in general battery design, an insulating coating layer is coated on the edge of the positive electrode active material coating layer to prevent the negative electrode from contacting the positive electrode current collector to cause internal short circuit.

As shown in fig. 1A to 1C, which are schematic structural views of a conventional pole piece 200', the pole piece 200' includes a current collector 100', an active material coating 3', and an insulating layer (not shown), wherein the active material coating 3' is located on a surface 101' coated with an active material in a thickness direction of the current collector 100 '. When the pole piece 200' shown in fig. 1A to 1C is prepared, although the insulating layer is coated, more burrs are still easy to generate during die cutting, and the burrs pierce the separator to cause direct contact between the positive electrode and the negative electrode, so that safety problems such as short circuit and the like occur.

Disclosure of Invention

The utility model aims to provide a current collecting unit.

It is another object of the present utility model to provide a pole piece.

It is still another object of the present utility model to provide a battery.

A current collecting unit according to an aspect of the present utility model includes: a substrate; the insulating layers are positioned on the side surfaces of the substrate in the thickness direction and comprise a plurality of insulating strips which are distributed at intervals in the width direction, and the thickness of the insulating strips in the insulating layers is gradually decreased from inside to outside in the width direction.

According to the technical scheme, the step-shaped insulating strips with the decreasing thickness from inside to outside in the width direction are arranged, the degree of fit with the knife edge size of the die-cutting knife is improved, the slope of the knife edge during die-cutting is reduced, buffering is formed, and burrs can be better avoided.

In one or more embodiments of the current collecting unit, the current collecting unit is composed of the substrate, the at least one set of insulating layers.

In one or more embodiments of the current collecting unit, the decreasing thickness of the plurality of insulating strips in the insulating layer is 3-30 μm, and the width of a single insulating strip is 0.3-10mm.

In one or more embodiments of the current collecting unit, the insulation bar at the innermost side of the insulation layer in the width direction is a first insulation bar, and the thickness of the first insulation bar is 10-70 μm.

In one or more embodiments of the current collecting unit, the substrate includes a metal foil and a conductive coating layer on at least one side surface of the metal foil in a thickness direction, and the insulating layer is on a side surface of the conductive coating layer away from the metal foil.

In one or more embodiments of the current collecting unit, the substrate comprises a metal foil.

In one or more embodiments of the current collecting unit, the conductive coating has a thickness of 0.5 to 3 μm.

In one or more embodiments of the current collecting unit, an innermost insulating strip in a width direction of the insulating layer is a first insulating strip located on a side surface of the conductive coating away from the metal foil.

According to another aspect of the present utility model, a pole piece includes an active material layer and a current collecting unit as described above, and an inner surface of the active material layer in a thickness direction is in contact with a substrate of the current collecting unit.

In one or more embodiments of the pole piece, the end surface of the active material layer in the width direction is in contact with a first insulating strip of the insulating layer of the current collecting unit.

According to the battery of the further aspect of the utility model, the battery comprises the second pole piece obtained by processing the pole piece, the second pole piece comprises a main body part and a pole lug part, the pole lug part is positioned on at least one side of the width direction of the main body part, and the insulating layer is positioned on the pole lug part.

Drawings

The above and other features, properties and advantages of the present utility model will become more apparent from the following description of the accompanying drawings and embodiments in which like reference numerals refer to like features throughout, it being noted that these drawings are given by way of example only, which are not drawn to scale and should not be construed to limit the true scope of the utility model, wherein:

FIG. 1A is a schematic view of a pole piece of a prior art embodiment;

FIG. 1B is a schematic view of the pole piece of FIG. 1A from another view;

FIG. 1C is a schematic view of another prior art pole piece with a view angle;

FIG. 2A is a schematic view of a pole piece with three insulating strips according to an embodiment;

FIG. 2B is a schematic view of the pole piece of FIG. 2A from another view;

FIG. 2C is a schematic view of another embodiment of a pole piece with three insulating strips in a view;

FIG. 3A is a schematic view of a pole piece with two insulating strips according to an embodiment;

FIG. 3B is a schematic view of the pole piece of FIG. 3A from another view;

FIG. 3C is a schematic view of another embodiment of a pole piece with two insulating strips;

FIG. 4A is a schematic view of another embodiment of a pole piece with three insulating strips in a view;

FIG. 4B is a schematic view of the pole piece of FIG. 4A from another view;

FIG. 4C is a schematic view of a pole piece with three insulating strips according to another embodiment;

FIG. 5A is a schematic view of another embodiment of a pole piece with two insulating strips in a view;

FIG. 5B is a schematic view of the pole piece of FIG. 5A from another view;

FIG. 5C is a schematic view of a pole piece with two insulating strips according to another embodiment;

fig. 6 is a schematic structural view of a battery according to an embodiment.

Reference numerals:

200' -pole piece;

100' -current collector;

a 3' -active material coating;

101' -coating the surface of the active material;

100-current collecting units;

1-a substrate;

101-side surfaces of a substrate;

11-a metal foil;

12-a conductive coating;

2-an insulating layer;

21-an upper insulating layer;

22-a lower insulating layer;

20-insulating strips;

201-a first insulating strip;

3-an active material layer;

31-an inner surface;

32-end face;

200-pole pieces;

4-a second pole piece;

41-a main body portion;

42-pole ear;

300-battery.

Detailed Description

Reference will now be made in detail to the various embodiments of the utility model, examples of which are illustrated in the accompanying drawings and described below. While the utility model will be described in conjunction with the exemplary embodiments, it will be appreciated that the present description is not intended to limit the utility model to those exemplary embodiments. On the contrary, the utility model is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the utility model as defined by the appended claims.

In the following description, the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer" or other orientation are based on the orientation or positional relationship shown in the drawings, for convenience of description and simplicity of description, and are not indicative or implying that the apparatus or components in question must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, although terms used in the present application are selected from publicly known and commonly used terms, some terms mentioned in the specification of the present application may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Furthermore, it is required that the present application be understood, not simply by the actual terms used but by the meaning of each term lying within.

Meanwhile, the present application uses specific words to describe embodiments of the present application. Reference to "one embodiment" and/or "an embodiment" means that a particular feature, structure, or characteristic is associated with at least one embodiment of the present application. Thus, it should be emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" in various positions in this specification are not necessarily referring to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the present application may be combined as suitable.

Flowcharts are used in this application to describe the operations performed by systems according to embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in order precisely. Other operations may also be added to or removed from these processes.

Hereinafter, embodiments of the present utility model will be described based on the drawings. However, the embodiments shown below are examples of current collecting units, electrode tabs, and batteries for embodying the technical ideas of the present utility model, and the current collecting units, electrode tabs, and batteries of the present utility model are not particularly limited to the following. Further, in order to facilitate understanding of the scope of the claims, the numbers corresponding to the elements shown in the examples are given to the elements shown in the columns of "claims" and "summary of the utility model". However, the elements shown in the claims are by no means intended to be specific as elements of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the embodiments are not intended to limit the scope of the present utility model to those described herein unless specifically stated, but are merely illustrative examples.

However, the dimensions, positional relationships, and the like of the members shown in the drawings may be exaggerated for clarity. In the following description, the same names and symbols denote the same or similar members, and detailed description thereof is omitted. Further, each element constituting the present utility model may be a plurality of elements formed by the same member, and one member may also serve as a plurality of elements, or conversely, the functions of one member may be shared by a plurality of members. In the present specification, "upper" is used not only in the case of being in contact with the upper surface but also in the case of being formed above in a spaced-apart manner, and also in the meaning of including a layer and a layer having an intervening layer therebetween.

As shown in the current collector 100' of fig. 1A to 1C, the inventors of the present application have found that, although the insulating layer is coated, more burrs are still easily generated during die cutting, because the slopes between the edge of the die cutter and the surface to be die-cut are larger, and the burrs are more caused by direct die cutting. In addition, with the current collector 100', the surface 101' coated with the active material is planar, it is difficult to precisely control the coating width of the active material, and the edge may be caught poorly.

Based on the above consideration, the inventor has conducted intensive studies and designed a current collecting unit, which improves the fit with the knife edge dimension of the die-cutting knife by arranging a plurality of step-shaped insulating strips with decreasing thickness from inside to outside in the width direction, reduces the slope of the knife edge during die-cutting, forms buffering, and can better avoid the generation of burrs.

Although the current collecting unit disclosed in the embodiment of the present application is applicable to the secondary battery to reduce die cutting burrs, the current collecting unit is not limited thereto, as long as the battery can apply the current collecting unit disclosed in the embodiment of the present application.

Referring to the drawings, in one embodiment, the current collecting unit 100 may have a specific structure including a substrate 1 and at least one set of insulating layers 2. At least one group of insulating layers 2 is provided on the side surface 101 in the thickness direction of the substrate 1, the insulating layers 2 include a plurality of insulating strips 20 spaced apart in the width direction, and the thickness of the plurality of insulating strips 20 in the insulating layers 2 decreases sequentially from inside to outside in the width direction. Specifically, as shown in fig. 2B, 3B, 4B, and 5B, the insulating layers 2 may be located on only one side surface 101 in the thickness direction of the substrate, or as shown in fig. 2C, 3C, 4C, and 5C, the plurality of sets of insulating layers 2 may be located on both side surfaces 101 in the thickness direction of the substrate. As shown in fig. 2A, 3A, 4A, and 5A, the two insulating layers 2 may be located on both sides of the width direction of the active material layer 3, respectively, and the upper insulating layer 21 and the lower insulating layer 22 may be located on both sides.

The meaning of "current collecting unit 100" herein means a current collector having a similar function to that of a current collector commonly used in the art, i.e., collecting current, but structurally includes other functional coating structures such as an insulating layer, a conductive coating, etc., as compared to the current collector commonly used in the art.

The term "substrate 1" as used herein means a structure or part that serves as a base plane for coating an active material and can collect current, and the current generated by the active material of the battery is collected to form a larger current to be output to the outside, as shown in fig. 2A and 3A, the substrate 1 is a rectangular sheet structure, but is not limited to the specific structure in the above-described drawings, and may be other shapes, such as a circular sheet, a square sheet, etc., and is designed according to practical requirements.

The term "insulating layer 2" as used herein means a coating structure which is generally located on at least one side in the width direction of the active material layer and blocks the passage of current, and can effectively prevent the problem of short circuit caused by the contact between the positive electrode sheet and the negative electrode sheet. The cross-sectional shape of the insulating strip 20 is not limited to the rectangular shape shown in fig. 2C, and may be, for example, trapezoidal, elliptical, semicircular, or the like.

The term "spaced-apart" as used herein means that two adjacent insulating strips 20 are spaced apart in the width direction, and a plurality of spaced-apart insulating strips 20 as shown in fig. 2A to 5C are formed in a stripe-like structure similar to a zebra stripe, and the number of the plurality of strips is not limited to 2 or 3 strips as shown in the drawings, but may be more, and the design coating is performed according to actual requirements.

The meaning of "decreasing from inside to outside" here means that, in each group of insulating layers, the insulating strips located at the innermost side in the width direction are thickest, and the insulating strips located at the outer side in the width direction are smaller in thickness than the insulating strips located at the inner side, and as shown in fig. 4B, the plurality of insulating strips 20 in the two groups of insulating layers 2 constitute step-like insulating layers like high in the middle and low in the both sides.

The die-cutting knife has the beneficial effects that the step-shaped insulating strips with the decreasing thickness from inside to outside in the width direction are arranged, so that the degree of fit with the knife edge size of the die-cutting knife is improved, the slope of the knife edge during die-cutting is reduced, the buffer is formed, and burrs can be better avoided.

Referring to fig. 2A in combination with fig. 2B and fig. 4B, in some embodiments, the specific structure of the insulating strips 20 may be that the sequentially decreasing thickness of the plurality of insulating strips 20 in the insulating layer 2 is 3-30 μm, and the width of the single insulating strip is 0.3-10mm. Specifically, as shown in fig. 2B, the thickness of the insulating strips 20 decreases by the same value from inside to outside in the width direction, for example, the thickness difference between two adjacent insulating strips may be 10 μm, or the thickness decrease from inside to outside may be different, for example, the innermost insulating strip may be a first insulating strip, the outside of the first insulating strip may be a second insulating strip, the outside of the second insulating strip may be a third insulating strip, where the thickness of the second insulating strip and the first insulating strip decreases by 5 μm, the thickness of the third insulating strip decreases by 8 μm, and the above specific values are only examples, and the decreasing thickness design may be performed according to practical requirements. As shown in fig. 2A, the widths of the insulating strips 20 may be the same or different, and the spacing distances between the insulating strips 20 may be the same or different, not limited to the one shown in the drawings.

Referring to fig. 2B to 5C, in some embodiments, the current collecting unit 100 may have a specific structure in which the insulation bar 20 at the innermost side in the width direction of the insulation layer 2 is a first insulation bar 201, and the thickness of the first insulation bar 201 is 10-70 micrometers, preferably 25-50 micrometers. Therefore, the battery capacity is not affected, the insulating layer thickness is good, and burrs can be reduced during die cutting.

Referring to fig. 2A to 3C, in some embodiments, the substrate 1 may have a specific structure that the substrate 1 includes a metal foil 11 and a conductive coating 12, the conductive coating 12 is located on at least one side surface of the metal foil 11 in a thickness direction, and an insulating layer is located on a side surface of the conductive coating 12 away from the metal foil 11. Specifically, in some embodiments, the first insulating strip 201 is located on a side surface of the conductive coating 12 away from the metal foil 11, and other insulating strips are located on a side surface of the metal foil 11 in a thickness direction, where the meaning of "metal foil 11" described below refers to a metal foil capable of collecting current, and may be, for example, copper foil, aluminum foil, tin foil, nickel foil, titanium foil, or stainless steel foil.

The meaning of the conductive coating 12 is an intermediate layer structure between the metal foil 11 and the active material layer 3, which can effectively improve interface contact resistance between the current collecting unit and the active material, improve bonding strength between the active material and the current collecting unit, and reduce the peeling problem of the active material during the electrode cycle. The conductive coating 12 may be a carbon material, i.e., the conductive coating may be a carbon coating, but not limited to, and the carbon coating may include one or more of conductive carbon black, carbon nanofibers, graphite powder, carbon nanotubes, graphene, etc. to provide a better static conductive performance, collect micro-current of the active material, thereby greatly reducing contact resistance between the positive/negative active material and the current collecting unit, improving adhesion capability between the positive/negative active material and the current collecting unit, reducing usage amount of an adhesive, and further remarkably improving overall performance of the battery. In some embodiments, the thickness of the conductive coating 12 is 0.5-3 microns.

Specifically, a conductive coating 12 is coated on the metal foil 11, and an active material including lithium iron phosphate or the like is coated on the conductive coating 2 as the active material layer 3.

In some embodiments, as shown in fig. 2C and 3C, the substrate 1 may be composed of only the metal foil 11 and the conductive coating 12. In other embodiments, the base 1 may also be a composite current collector (not shown) including an insulating substrate (e.g., a polymer material) and metal layers on both sides of the insulating substrate, and the conductive coating 12.

Referring to fig. 4A to 5C, in some embodiments, the specific structure of the substrate 1 may be that the substrate 1 includes a metal foil 11. Specifically, an active material including lithium nickel cobalt manganate or lithium nickel cobalt aluminate or the like is directly coated on the metal foil 11 as the active material layer 3.

In some embodiments, as shown in fig. 4C, 5C, the substrate 1 may be composed of only the metal foil 11. In other embodiments, the base 1 may also be a composite current collector (not shown in the drawings) including an insulating substrate (e.g., a polymer material) and metal layers on both sides of the insulating substrate.

Referring to fig. 2A to 5C, in one embodiment, the specific structure of the electrode sheet 200 may be such that it includes the active material layer 3 and the current collecting unit 100 as described above, the inner surface 31 of the active material layer in the thickness direction is in contact with the substrate 1 of the current collecting unit 100, and the end surface 32 of the active material layer in the width direction is in contact with the first insulating strip 201 of the insulating layer 2 of the current collecting unit 100. The pole piece of the embodiment can reduce the risk of short circuit caused by direct contact between the positive electrode and the negative electrode due to burrs. The terms "inner" and "outer" in this application are used interchangeably and refer to "inner" relative to the center of the substrate 1 and "outer" relative to the center of the substrate 1. Taking two surfaces of the active material layer 3 in the thickness direction as an example, a surface of the active material layer 3 distant from the substrate 1 in the thickness direction is an outer surface, and a surface of the active material layer 3 close to the substrate 1 in the thickness direction is an inner surface.

In some embodiments, as shown in fig. 6, the pole piece 200 is processed to obtain the second pole piece 4, where the second pole piece 4 includes a main body 41 and a pole ear portion 42, the pole ear portion 42 is located on at least one side of the width direction of the main body 41, the active material layer 3 is located on the main body 41, and the insulating layer 2 is located on the pole ear portion 42. In still other embodiments, the active material layer 3 may also be partially located at the tab portion 42. The above embodiments of the body portion 41 and the tab portion 42 are only examples, and not limiting as to the structural layers that the body portion 41 and the tab portion 42 can include, the body portion 41 and the tab portion 42 may also include other coatings, but the body portion does not include a coating that would fail in combination with the active material layer, such as an insulating layer. The processing may be that the pole piece 200 shown in fig. 3A or fig. 4A is die-cut to form a pole lug, and then is slit along a middle position in a width direction to obtain a pole piece with a pole lug portion 42 on one side, or is directly die-cut to form a pole piece with a pole lug portion 42 on both sides, in addition, before and after the die-cutting, the pole piece may be slit along a direction parallel to the width direction according to a requirement of actually cutting the length of the pole piece, the slitting and the die-cutting are generally adopted in the art, specifically, the slitting may be laser cutting, the die-cutting may be die-cutting or laser cutting, the laser cutting and the die cutting are all conventional processing methods in the art, and only examples of processing methods are not limited thereto, and other methods may be adopted as long as the process capable of effectively cutting the second pole piece 4 including the pole lug portion 42 and the pole piece main body portion 41 can be obtained. During die cutting, the insulating layer 2 is reserved on the lug part 41, and the insulating layer 2 of the main body part 41 is completely cut off, so that the lithium ion is easy to take off and insert after being mixed due to unavoidable mixing with an active material during coating, and the insulating coating is easy to drop, so that the safety problem is caused. Only remain the insulating layer of utmost point ear so can prevent active material and insulating layer compounding part and become invalid in the circulation later stage, lead to the insulating layer to drop, take place safety problems such as short circuit.

Referring to fig. 2C in conjunction with fig. 3C, in some embodiments, the specific structure of pole piece 200 may be that pole piece 200 is a positive pole piece. Specifically, as shown in fig. 2C, 3C, 4C, and 5C, the metal foil 11 is an aluminum foil, and the thickness of the active material layer 3 is 30 to 120 micrometers, preferably 50 to 100 micrometers. The composition of the active material layer 3 may include lithium manganate, lithium iron phosphate, lithium nickel cobalt manganate, lithium cobalt oxide, and the like.

In some embodiments, the electrode sheet 200 may also be a negative electrode sheet, the metal foil 11 is a copper foil, the composition of the active material layer may include one or more of a carbon material or a non-carbon material, the carbon material includes a graphite material (natural graphite, artificial graphite or mesophase carbon spheres) or other carbon system (hard carbon, soft carbon or graphene), and the non-carbon material may be a titanium-based material, a silicon-based material, a tin-based material, a nitride or metallic lithium, etc.

Referring to fig. 2A to 5C in combination with fig. 6, in one embodiment, the specific structure of the battery 300 may be that the battery 300 includes the second electrode sheet 4 as above. The battery adopting the embodiment can reduce the risk of short circuit caused by direct contact between the positive electrode and the negative electrode due to burrs. Specifically, the battery 300 may be manufactured by a lamination process or a winding process, and in the embodiment shown in fig. 6, the battery 300 is a secondary battery, and the winding process is used to manufacture a battery with a winding type cell. The structure of the battery cell is not limited to the cross section similar to ellipse (racetrack) shown in the figure, so as to form a square battery cell, for example, a cylindrical battery cell, a soft package battery cell, and the like, which are not limited thereto. In addition, the electrode assembly composed of the positive electrode tab, the negative electrode tab, and the separator needs to be integrated with an electrolyte, for example, an electrolyte immersed in a liquid state, and the electrode assembly and the electrolyte are generally contained inside a chamber provided in a battery case. It is understood that the battery 300 is not limited to the embodiment shown in the drawings and the secondary battery, and may be, for example, a nickel-hydrogen battery, a nickel-chromium battery, a lead-acid battery, a polymer lithium ion battery, or the like.

While the utility model has been described in terms of preferred embodiments, it is not intended to be limiting, but rather to the utility model, as will occur to those skilled in the art, without departing from the spirit and scope of the utility model. Therefore, any modification, equivalent variation and modification of the above embodiments according to the technical substance of the present utility model fall within the protection scope defined by the claims of the present utility model.

Claims (10)

1. A current collecting unit, comprising:

a substrate;

the insulating layers are positioned on the side surfaces of the substrate in the thickness direction and comprise a plurality of insulating strips which are distributed at intervals in the width direction, and the thickness of the insulating strips in the insulating layers is gradually decreased from inside to outside in the width direction.

2. The current collecting unit according to claim 1, wherein the current collecting unit is composed of the substrate, the at least one set of insulating layers.

3. The current collecting unit according to claim 1, wherein a decreasing thickness of a plurality of said insulating strips in said insulating layer is 3 to 30 μm and a width of a single one of said insulating strips is 0.3 to 10mm.

4. The current collecting unit according to claim 1, wherein the insulation bar at the innermost side in the width direction of the insulation layer is a first insulation bar having a thickness of 10 to 70 μm.

5. The current collecting unit according to claim 1, wherein the substrate comprises a metal foil and a conductive coating layer on at least one side surface in a thickness direction of the metal foil, and the insulating layer is on a side surface of the conductive coating layer remote from the metal foil.

6. The current collecting unit according to claim 5, wherein the conductive coating has a thickness of 0.5 to 3 μm.

7. The current collecting unit according to claim 5, wherein the insulation bar of the innermost widthwise direction of the insulation layer is a first insulation bar located on a side surface of the conductive coating remote from the metal foil.

8. The current collecting unit of claim 1, wherein the substrate comprises a metal foil.

9. A pole piece comprising an active material layer and the current collecting unit according to any one of claims 1 to 8, wherein an inner surface in a thickness direction of the active material layer is in contact with a base of the current collecting unit, and an end surface in a width direction of the active material layer is in contact with a first insulating strip of an insulating layer of the current collecting unit.

10. A battery comprising the second pole piece processed by the pole piece according to claim 9, wherein the second pole piece comprises a main body portion and a pole ear portion, the pole ear portion is located on at least one side of the main body portion in the width direction, and the insulating layer is located on the pole ear portion.