CN220873622U - Negative pole piece, electrochemical device and electric equipment - Google Patents

Abstract

The application provides a negative pole piece, an electrochemical device and electric equipment, and relates to the technical field of energy storage. The negative pole piece comprises a negative pole current collector and an active material layer arranged on the surface of the negative pole current collector, the active material layer comprises a central area and an edge area, the edge area is positioned at the periphery of the central area, the central area is provided with a plurality of first blind holes, the edge area is provided with a plurality of second blind holes, and the sum of the volumes of the second blind holes is larger than the sum of the volumes of the first blind holes. By the arrangement, the electrolyte diffusion speed of the edge area is higher, the stress accumulation of the edge area is reduced in the circulation process of the electrochemical device, and the circulation expansion of the electrochemical device is improved.

Description

Negative pole piece, electrochemical device and electric equipment

Technical Field

The application relates to the technical field of energy storage, in particular to a negative electrode plate, an electrochemical device and electric equipment.

Background

Along with the progress of science and technology and the acceleration of life pace of people, the requirements of people on the charging speed and the endurance of electronic equipment are higher and higher, and the capacity of an electrochemical device of the electronic equipment is obviously lost in a rapid charging mode. Taking a silicon cathode of an electrochemical device as an example, the silicon material can obviously improve the capacity of the electrochemical device, but the silicon cathode is easy to generate larger volume expansion in the lithium intercalation process, so that the electrochemical device is deformed and stress concentration phenomenon is generated, and the charge and discharge performance and the safety performance of the electrochemical device are affected.

Disclosure of utility model

In view of the above, the application provides a negative electrode plate, an electrochemical device and electric equipment, so as to improve the charge and discharge performance and the safety performance of the electrochemical device.

Specifically, the method comprises the following technical scheme:

In a first aspect, the application provides a negative electrode plate, which comprises a negative electrode current collector and an active material layer arranged on the surface of the negative electrode current collector, wherein the active material layer comprises a central region and an edge region, the edge region is positioned at the periphery of the central region, a plurality of first blind holes are formed in the central region, a plurality of second blind holes are formed in the edge region, and the sum of the volumes of the second blind holes is larger than the sum of the volumes of the first blind holes.

In an alternative embodiment, on the surface of the active material layer facing away from the negative electrode current collector, the sum of the pore areas of the first blind holes is 20% -60% of the surface area of the active material layer, the sum of the pore areas of the second blind holes is 40% -80% of the surface area of the active material layer, and the sum of the pore areas of the first blind holes is smaller than the sum of the pore areas of the second blind holes.

In a possible implementation manner, the depth H1 of the first blind hole is 10% -20% of the thickness of the active material layer, and the depth H2 of the second blind hole is 20% -40% of the thickness of the active material layer.

In an alternative implementation mode, the first blind hole and the second blind hole are all circular, the aperture D1 of the first blind hole is 1mm ~ 3mm, the aperture D2 of the second blind hole is 2mm ~ 5mm, and satisfy: d1 is less than D2.

In an alternative embodiment, a distance W1 between two adjacent first blind holes along the length direction of the negative electrode plate is 25 mm-50 mm, and a distance W2 between two adjacent first blind holes along the width direction of the negative electrode plate is 10 mm-20 mm.

In an alternative embodiment, a plurality of the first blind holes are distributed in an array in the central region.

In an alternative embodiment, the distance between two adjacent second blind holes is 10 mm-30 mm.

In an alternative embodiment, a plurality of said second blind holes are spaced around said central region.

In a second aspect, the present application provides an electrochemical device comprising the negative electrode tab provided by any one of the embodiments of the first aspect.

In a third aspect, the present application provides an electric device, including an electrochemical device provided in an embodiment of the second aspect, where the electrochemical device is configured to supply power to the electric device.

The technical scheme provided by the embodiment of the application has the beneficial effects that at least: the first blind hole and the second blind hole are respectively formed in the central area and the edge area of the negative electrode plate, so that the diffusion speed of lithium ions and electrolyte in the negative electrode plate can be improved, the charging speed of an electrochemical device is improved, and the high-power charging requirement is met; the sum of the volumes of the second blind holes of the edge area is larger than the sum of the volumes of the first blind holes of the central area, so that the diffusion speed of electrolyte in the edge area is higher, the stress accumulation in the edge area is reduced in the circulation process of the electrochemical device, the circulation expansion of the electrochemical device is improved, the charge and discharge performance and the safety performance of the electrochemical device are improved, and the long endurance requirement of the electrochemical device under high multiplying power is met.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present application;

fig. 2 is a schematic view of an active material layer structure of a negative electrode tab according to an embodiment of the present application.

Reference numerals in the drawings denote:

1-a negative electrode piece; 11-a negative electrode current collector; 12-an active material layer; 121-a central region; 1211-a first blind hole; 122-edge region; 1221-second blind hole.

Specific embodiments of the present application have been shown by way of the above drawings and will be described in more detail below. The drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but rather to illustrate the inventive concepts to those skilled in the art by reference to the specific embodiments.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

Orientation terms such as "upper", "lower", "side", etc. in the embodiments of the present application are generally based on the relative relationship of orientations shown in the figures, and these orientation terms are used merely for more clearly describing the structure and the relationship between structures, and are not intended to describe absolute orientations. The orientation may change when the product is placed in different orientations, e.g. "up", "down" may be interchanged.

Unless defined otherwise, all technical terms used in the embodiments of the present application have the same meaning as commonly understood by one of ordinary skill in the art. Some technical terms appearing in the embodiments of the present application are described below.

In order to make the technical scheme and advantages of the present application more apparent, embodiments of the present application will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1 and 2, an embodiment of the present application provides a negative electrode tab 1, which includes a negative electrode current collector 11 and an active material layer 12 disposed on a surface of the negative electrode current collector 11, where the active material layer 12 includes a central region 121 and an edge region 122, the edge region 122 is located at an outer periphery of the central region 121, the central region 121 is provided with a plurality of first blind holes 1211, the edge region 122 is provided with a plurality of second blind holes 1221, and a sum of volumes of the plurality of second blind holes 1221 is greater than a sum of volumes of the plurality of first blind holes 1211.

Specifically, the negative electrode tab 1 is suitable for an electrochemical device such as a lithium battery, and the electrochemical device may include a wound cell structure or a laminated cell structure.

The negative electrode current collector 11 may be a metal foil, and specifically may be a copper foil. The negative electrode current collector 11 has two surfaces disposed opposite to each other in the thickness direction thereof, and the active material layer 12 is disposed on at least one of the two surfaces, and for example, as shown in fig. 1, both surfaces of the negative electrode current collector 11 disposed opposite to each other in the thickness direction thereof are provided with the active material layer 12.

Illustratively, the active material layer 12 includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material includes carbon materials such as graphite, silicon oxygen material, silicon carbon material, hard carbon or soft carbon. The conductive agent comprises at least two of conductive carbon black, ke Qinhei, carbon nano tubes and graphene, and the adhesive comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polypropylene, polyacrylic acid, polyacrylate, polyacrylonitrile, sodium carboxymethyl cellulose, styrene-butadiene rubber and polyurethane. The negative electrode active material, the conductive agent and the adhesive are stirred and coated on the surface of the negative electrode current collector 11, and the negative electrode plate 1 is formed through the procedures of baking, cold pressing and the like.

The negative electrode tab 1 may be rectangular, the negative electrode tab 1 has a length direction, a width direction, and a thickness direction, the horizontal direction in fig. 1 and the vertical direction in fig. 2 are the length direction of the negative electrode tab 1, the horizontal direction in fig. 2 is the width direction of the negative electrode tab 1, and the vertical direction in fig. 1 is the thickness direction of the negative electrode tab 1.

The shape of the active material layer 12 is adapted to the shape of the negative electrode current collector 11, and the edge region 122 is located outside the central region 121. In an alternative embodiment, the number of the edge regions 122 is two, and the two edge regions 122 are arranged on both sides of the central region 121 in the width direction of the negative electrode tab 1. In another alternative embodiment, as shown in FIG. 2, the edge region 122 is annular around the periphery of the central region 121.

In the prior art, the volume expansion of the negative electrode tab 1 occurs during the charging process of the electrochemical device, especially the stress of the edge region 122 is difficult to release, the deformation of the negative electrode tab 1 and the electrochemical device is deteriorated, and the lithium precipitation degree of the edge region 122 is higher than that of the center region 121, so that the service life of the electrochemical device is shortened.

In the embodiment of the application, since the blind holes are formed in the central area 121 and the edge area 122, the negative electrode plate 1 has better electrolyte wettability, the diffusion speed of the electrolyte in the negative electrode plate 1 is improved, and the dynamic performance of the negative electrode plate 1 is improved. Moreover, since the sum of the volumes of the plurality of second blind holes 1221 is greater than the sum of the volumes of the plurality of first blind holes 1211, it may be specifically shown that at least one of the number, depth, porosity and opening size of the second blind holes 1221 in the edge region 122 is greater than the corresponding parameter of the first blind holes 1211, so that the electrolyte in the center region 121 can rapidly diffuse into the edge region 122, thereby reducing the stress accumulation in the edge region 122 and improving the cyclic expansion of the electrochemical device.

Specifically, the opening shapes of the first blind hole 1211 and the second blind hole 1221 may be circular, elliptical, polygonal, irregular, or the like. The dimensions of the first blind hole 1211 and the second blind hole 1221 may be uniform throughout the depth direction thereof, for example, the first blind hole 1211 or the second blind hole 1221 may have a cylindrical shape, a prismatic shape, or the like; the dimensions of the first blind hole 1211 and the second blind hole 1221 may also be gradually changed in the own depth direction, for example, the first blind hole 1211 or the second blind hole 1221 may be in an inverted cone shape, a truncated pyramid shape, or the like, and the opening area thereof may be gradually reduced in the own depth direction.

Specifically, the first blind hole 1211 and the second blind hole 1221 may be formed by structuring on the surface of the active material layer 12 by laser, chemical etching, or the like.

It can be understood that the depth direction of the first blind hole 1211 and the second blind hole 1221 is parallel to the thickness direction of the anode tab 1, and the depth of the first blind hole 1211 and the depth of the second blind hole 1221 are smaller than the thickness of the active material layer 12, that is, one end of the first blind hole 1211 and the second blind hole 1221 is opened, and the other end is closed, so as to prevent the anode current collector 11 from being corroded by the electrolyte when being exposed to the electrolyte, thereby avoiding reducing the cycle efficiency and the life of the electrochemical device.

According to the negative electrode plate 1 provided by the embodiment of the application, the first blind hole 1211 and the second blind hole 1221 are respectively formed in the central area 121 and the edge area 122 of the negative electrode plate 1, so that the diffusion speed of lithium ions and electrolyte in the negative electrode plate 1 can be improved, the charging speed of an electrochemical device is improved, and the high-power charging requirement is met; by setting the sum of the volumes of the second blind holes 1221 of the edge region 122 to be larger than the sum of the volumes of the first blind holes 1211 of the central region 121, the diffusion speed of the electrolyte in the edge region 122 can be increased, the stress accumulation in the edge region 122 can be reduced in the circulation process of the electrochemical device, the circulation expansion of the electrochemical device can be improved, the charge and discharge performance and the safety performance of the electrochemical device can be improved, and the long endurance requirement of the electrochemical device under high multiplying power can be met.

In a specific embodiment, on the surface of the active material layer 12 facing away from the negative electrode current collector 11, the sum of the hole areas of the plurality of first blind holes 1211 is 20% to 60% of the surface area of the active material layer 12, the sum of the hole areas of the plurality of second blind holes 1221 is 40% to 80% of the surface area of the active material layer 12, and the sum of the hole areas of the plurality of first blind holes 1211 is smaller than the sum of the hole areas of the plurality of second blind holes 1221.

Illustratively, the sum of the pore areas of the plurality of first blind pores 1211 may be 20%, 30%, 40%, 60%, etc. of the surface area of the active material layer 12 facing away from the negative electrode current collector 11, and the sum of the pore areas of the plurality of second blind pores 1221 may be 40%, 60%, 70%, 80%, etc. of the surface area of the active material layer 12 facing away from the negative electrode current collector 11.

It will be appreciated that the sum of the hole areas of the first blind holes 1211 is: the sum of the opening areas of the first blind holes 1211 on the surface of the active material layer 12 facing away from the negative electrode current collector 11, and the sum of the hole areas of the second blind holes 1221 is: the sum of the opening areas of the second blind holes 1221 on the surface of the active material layer 12 facing away from the negative electrode current collector 11.

In this embodiment, the sum of the hole areas of the plurality of first blind holes 1211 is smaller than the sum of the hole areas of the plurality of second blind holes 1221, which is advantageous in reducing the stress accumulation in the edge region 122 and improving the charge-discharge performance and safety performance of the electrochemical device.

In a specific embodiment, the depth H1 of the first blind hole 1211 is 10% to 20% of the thickness of the active material layer 12, and the depth H2 of the second blind hole 1221 is 20% to 40% of the thickness of the active material layer 12. Illustratively, the depth H1 of the first blind via 1211 may be 10%, 13%, 16%, 20%, etc. of the thickness of the active material layer 12, and the depth H2 of the second blind via 1221 may be 20%, 30%, 35%, 40%, etc. of the thickness of the active material layer 12. Optionally, the depth H2 of the second blind hole 1221 is greater than the depth H1 of the first blind hole 1211, so as to increase the diffusion speed of the electrolyte and lithium ions to the edge region 122, and improve the stress accumulation and lithium precipitation degree of the edge region 122.

In an alternative embodiment, the first blind hole 1211 and the second blind hole 1221 are both circular, the aperture D1 of the first blind hole 1211 is 1mm to 3mm, the aperture D2 of the second blind hole 1221 is 2mm to 5mm, and the following are satisfied: d1 is less than D2. It is understood that the first blind hole 1211 and the second blind hole 1221 are both circular means: on the surface of the active material layer 12 facing away from the anode current collector 11, the openings of the first blind hole 1211 and the second blind hole 1221 are circular in shape, and the apertures of the first blind hole 1211 and the apertures of the second blind hole 1221 are the apertures of the openings of the first blind hole 1211 and the second blind hole 1221 on the surface of the active material layer 12 facing away from the anode current collector 11.

Illustratively, the aperture D1 of the first blind bore 1211 may be 1mm, 1.5mm, 2mm, 3mm, etc., and the aperture D2 of the second blind bore 1221 may be 2mm, 3mm, 4mm, 5mm, etc. By setting D1 < D2, the opening size of the second blind hole 1221 is larger than that of the first blind hole 1211, the diffusion speed of electrolyte and lithium ions to the edge region 122 is further accelerated, the stress accumulation and lithium precipitation degree of the edge region 122 are improved, the charge and discharge performance and the safety performance of the electrochemical device are improved, and the long-endurance requirement of the electrochemical device under high multiplying power is met.

In an alternative embodiment, the spacing W1 between two adjacent first blind holes 1211 along the length direction of the negative electrode tab 1 is 25mm to 50mm, and the spacing W2 between two adjacent first blind holes 1211 along the width direction of the negative electrode tab 1 is 10mm to 20mm. Illustratively, the spacing W1 between two adjacent first blind holes 1211 in the length direction of the anode electrode tab 1 may be 25mm, 35mm, 40mm, 50mm, etc., and the spacing W2 between two adjacent first blind holes 1211 in the width direction of the anode electrode tab 1 may be 10mm, 13mm, 16mm, 20mm, etc.

The plurality of first blind holes 1211 are distributed in an array in the central area 121, and may specifically be in a rectangular array, an annular array, a circular array, or the like. For example, as shown in fig. 2, the plurality of first blind holes 1211 are distributed in a rectangular array of three rows and two columns in the central region 121, and the spacing between two adjacent rows of first blind holes 1211 is W1, and the spacing between two adjacent columns of first blind holes 1211 is W2.

In an alternative embodiment, the spacing between two adjacent second blind holes 1221 is 10mm to 30mm. Illustratively, the spacing between two adjacent second blind holes 1221 may be 10mm, 20mm, 25mm, 30mm, etc. Optionally, the distance between two adjacent second blind holes 1221 along the length direction of the anode electrode sheet 1 is smaller than W1, and/or the distance between two adjacent second blind holes 1221 along the width direction of the anode electrode sheet 1 is smaller than W2, so that the distribution density of the second blind holes 1221 in the edge region 122 is greater than that of the first blind holes 1211 in the central region 121, the diffusion speed of the electrolyte and lithium ions to the edge region 122 is further accelerated, the stress accumulation and lithium precipitation degree of the edge region 122 are improved, the charge-discharge performance and the safety performance of the electrochemical device are improved, and the long endurance requirement of the electrochemical device under high magnification is met.

Further, the plurality of second blind holes 1221 are spaced around the central region 121, as shown in fig. 2, and the plurality of second blind holes 1221 are arranged in a ring shape around the outer periphery of the central region 121. Illustratively, the spacing between two adjacent second blind holes 1221 in the length direction of the anode electrode tab 1 is 15mm to 30mm, the spacing between two adjacent second blind holes 1221 in the width direction of the anode electrode tab 1 is 10mm to 15mm, for example, the spacing between two adjacent second blind holes 1221 in the length direction of the anode electrode tab 1 may be 15mm, 20mm, 25mm, 30mm, or the like, and the spacing between two adjacent second blind holes 1221 in the width direction of the anode electrode tab 1 may be 10mm, 12mm, 14mm, 15mm, or the like.

In this embodiment, by providing a plurality of second blind holes 1221 spaced around the central region 121, the rate of diffusion of electrolyte and lithium ions from the central region 121 to the edge region 122 is substantially increased, improving the stress accumulation and lithium precipitation levels at the edge region 122.

In a second aspect, an embodiment of the present application provides an electrochemical device, including the negative electrode tab 1 provided in any of the above embodiments.

Specifically, the electrochemical device comprises a shell and a battery cell, wherein the battery cell is accommodated in the shell, and the shell plays a role in sealing and protecting the battery cell. The cells may be of a coiled cell structure or a laminated cell structure.

The cell may include at least one positive electrode tab, at least one negative electrode tab 1, and at least one separator layer between the positive electrode tab and the negative electrode tab 1. In one embodiment, the positive electrode sheet, the separator layer and the negative electrode sheet 1 are sequentially stacked and wound with each other to form a winding type cell structure. In another embodiment, the positive electrode sheet, the separator layer and the negative electrode sheet 1 are sequentially stacked in a crossing manner to form a stacked cell structure. The cell is placed in a shell, and an electrochemical device is prepared and formed through the procedures of liquid injection, formation, molding, sealing and the like.

The positive electrode sheet includes a positive electrode current collector, which may be a metal foil, and a positive electrode active material layer 12, which may be an aluminum foil. The positive electrode active material layer 12 may include one or more of lithium cobaltate, lithium manganate, lithium iron phosphate, and nickel cobalt manganate, and the material of the positive electrode active material layer 12 is not limited in the present application. The positive electrode active material layer 12 is provided on at least one of two surfaces of the positive electrode current collector that are disposed opposite to each other in the thickness direction thereof.

The membrane layer is a polymer isolating membrane which is used for separating the positive pole piece and the negative pole piece 1 and is provided with micropores, and can be made of a polymer functional material with a nanoscale micropore structure. The separator layer is used for preventing the positive pole piece from being contacted with the negative pole piece 1 to cause short circuit, and simultaneously, electrolyte ions pass through to prevent electrons from passing through. The separator layer can be a polyolefin microporous membrane, a polyethylene felt, a glass fiber felt, superfine glass fiber paper or the like, and the material of the separator layer is not limited in the application.

In a third aspect, an embodiment of the present application further provides an electric device, including the electrochemical device provided in the foregoing embodiment, where the electrochemical device is configured to supply power to the electric device. The electric equipment can be a mobile phone, a flat plate, an aircraft, an automobile, wearable equipment, a manipulator and the like, and can be other equipment needing to use an electrochemical device.

In the present disclosure, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless explicitly defined otherwise.

Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. The specification and examples are to be regarded in an illustrative manner only.

It is to be understood that the application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (10)

1. The utility model provides a negative pole piece (1), its characterized in that includes negative pole current collector (11) and set up in active material layer (12) on negative pole current collector (11) surface, active material layer (12) include central region (121) and marginal zone (122), marginal zone (122) are located the periphery of central region (121), a plurality of first blind holes (1211) have been seted up in central region (121), a plurality of second blind holes (1221) have been seted up in marginal zone (122), a plurality of the volumetric sum of second blind holes (1221) is greater than the volumetric sum of a plurality of first blind holes (1211).

2. The negative electrode tab (1) according to claim 1, characterized in that on the surface of the active material layer (12) facing away from the negative electrode current collector (11), the sum of the pore areas of the plurality of first blind holes (1211) is 20-60% of the surface area of the active material layer (12), the sum of the pore areas of the plurality of second blind holes (1221) is 40-80% of the surface area of the active material layer (12), and the sum of the pore areas of the plurality of first blind holes (1211) is smaller than the sum of the pore areas of the plurality of second blind holes (1221).

3. The negative electrode tab (1) according to claim 1, characterized in that the depth H1 of the first blind hole (1211) is 10% -20% of the thickness of the active material layer (12), and the depth H2 of the second blind hole (1221) is 20% -40% of the thickness of the active material layer (12).

4. The negative electrode tab (1) according to claim 1, wherein the first blind hole (1211) and the second blind hole (1221) are both circular, the aperture D1 of the first blind hole (1211) is 1mm to 3mm, the aperture D2 of the second blind hole (1221) is 2mm to 5mm, and the following are satisfied: d1 is less than D2.

5. The negative electrode tab (1) according to claim 1, wherein a pitch W1 between two adjacent first blind holes (1211) in a length direction of the negative electrode tab (1) is 25mm to 50mm, and a pitch W2 between two adjacent first blind holes (1211) in a width direction of the negative electrode tab (1) is 10mm to 20mm.

6. The negative electrode tab (1) according to claim 5, characterized in that a plurality of said first blind holes (1211) are distributed in an array in said central zone (121).

7. The negative electrode tab (1) according to claim 1, characterized in that the spacing between two adjacent second blind holes (1221) is 10 mm-30 mm.

8. The negative electrode tab (1) according to claim 7, characterized in that a plurality of said second blind holes (1221) are spaced around said central region (121).

9. Electrochemical device, characterized in that it comprises a negative electrode sheet (1) according to any one of claims 1 to 8.

10. An electrical consumer comprising the electrochemical device of claim 9 for powering the electrical consumer.