CN216389430U - Pole piece and battery - Google Patents

Abstract

The utility model provides a pole piece and a battery, wherein the pole piece comprises a current collector and active material layers arranged on at least one side surface of the current collector, at least one active material layer comprises a hole distribution area provided with a hole structure and a hole-free area not provided with the hole structure, and the hole distribution area and the hole-free area are alternately arranged on the active material layer at intervals along the length direction of the pole piece. On the basis of improving the cycle performance and the rate performance of the battery, the pole piece has the advantages of small capacity loss of the battery, small energy density loss of the battery and longer service life.

Description

Pole piece and battery

Technical Field

The utility model relates to the technical field of lithium ion batteries, in particular to a pole piece and a battery.

Background

The lithium ion battery has the advantages of high energy density, long cycle life, small self-discharge, no memory effect and the like, and has received wide attention and application since commercialization. With the increasing demand for lithium ion batteries with respect to capacity and cycle life, the development of higher energy density cathode materials is imminent.

Highly coated cell designs have become an effective means to increase energy density. However, the pole piece with high coating is thick, the electrolyte is not easy to permeate, and the liquid retention amount of the pole piece is insufficient, so that the diffusion distance of lithium ions is increased, the electrolyte cannot contact part of active substances in the pole piece, and the capacity exertion and the cycle life of the battery are seriously influenced. To solve the above problems, the design of the porous electrode sheet has proved to be an effective improvement method. The porous pole piece is easy to absorb and store electrolyte due to high porosity, and the diffusion distance of lithium ions is greatly reduced. Therefore, the cycle performance, the rate capability and the like of the lithium ion battery can be obviously improved.

However, in the prior art, holes are punched on the surface of the pole piece, active substances in a hole structure area on the pole piece fall off, the capacity loss is large, the energy density loss of the battery is large, the time of a customer using the battery is short, and the experience of the customer is poor.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problem that the liquid retention and the capacity of the conventional pole piece cannot be considered at the same time.

In order to solve the above problems, a first aspect of the present invention provides a pole piece, including a current collector and active material layers disposed on at least one side surface of the current collector, at least one of the active material layers includes a hole distribution region provided with a hole structure and a non-hole region not provided with a hole structure, and the hole distribution region and the non-hole region are alternately disposed on the active material layer at intervals along a length direction of the pole piece.

Further, the length of the cloth hole area is 1-5 mm.

Furthermore, the distance between any two adjacent cloth hole areas is 40-60 mm.

Further, the cloth hole area is provided with a plurality of the pore structures, and the pore structures are distributed in a regular shape.

Furthermore, the pore structures are distributed in a rectangular matrix, and the distance between any two adjacent pore structures is 80-120 mu m.

Further, the hole structure is a blind hole.

Further, the depth of the pore structure is one third to two thirds of the thickness of the active material layer.

Furthermore, the pore diameters of the pore structures are the same, and the pore diameter of the pore structure is 10-20 mu m.

Further, the active material layers are arranged on the surfaces of the two sides of the current collector, and the active material layers are both provided with a cloth hole area and a non-hole area.

According to the pole piece, the perforated hole distribution areas are arranged on the active material layer of the pole piece, and each hole distribution area is provided with the hole structure, so that the porosity of the pole piece is improved, the liquid retention capacity is improved, the diffusion distance of lithium ions can be greatly reduced, and the cycle performance and the rate performance of a battery are improved; in addition, the cloth hole area and the non-porous area are alternately arranged at intervals, the cloth hole area punched on the active material layer is discontinuous, and compared with the prior art that the holes are punched on the surface of the pole piece in the whole direction, the capacity loss of the battery is small, the energy density loss of the battery is also small, and the use time is longer.

The utility model provides a battery, which comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate, wherein a positive lug is arranged on the positive plate, and a negative lug is arranged on the negative plate; the positive plate and/or the negative plate is the plate.

The beneficial effects of the battery are the same as those of the pole piece, and are not described again here.

Drawings

FIG. 1 is a schematic structural diagram of a pole piece according to an embodiment of the present invention;

FIG. 2 is an enlarged schematic view of the perforated area of FIG. 1;

fig. 3 is a graph of cycle test results for batteries made with pole pieces in an embodiment of the utility model.

Description of reference numerals:

1-a cloth hole area; 2-non-porous region.

Detailed Description

The technical solutions in the embodiments of the present application will be described in detail and clearly with reference to the accompanying drawings. In the description of the present invention, it should be noted that, in the coordinate system XY provided herein, the X axis represents the length direction, and the Y axis represents the width direction. In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. The meaning of "at least one" is one or more unless specifically limited otherwise.

In the description of the embodiments of the present application, the description of the term "some preferred embodiments" means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one preferred embodiment or preferred example of the present invention. Throughout this specification, the schematic representations of the terms used above do not necessarily refer to the same implementation 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.

In order to further illustrate the present invention, the following examples are given to further illustrate the present invention.

With reference to fig. 1, the present embodiment provides a pole piece, including a current collector and an active material layer disposed on at least one side surface of the current collector, where at least one active material layer includes a hole distribution area 1 provided with holes and a non-hole area 2 not provided with holes, the hole distribution area 1 and the non-hole area 2 are alternately disposed on the active material layer along a length direction (i.e., an x-axis direction in fig. 1) of the pole piece, one non-hole area 2 is disposed between any two adjacent hole distribution areas 1, and each hole distribution area 1 is provided with a plurality of hole structures.

In the pole piece provided by the embodiment, the perforated hole distribution areas are arranged on the active material layer of the pole piece, and each hole distribution area is provided with the hole structure, so that the porosity of the pole piece is improved, the liquid retention capacity is improved, the diffusion distance of lithium ions can be greatly reduced, and the cycle performance and the rate performance of a battery are improved; in addition, the cloth hole area and the non-porous area are alternately arranged at intervals, the cloth hole area punched on the active material layer is discontinuous, and compared with the prior art that the holes are punched on the surface of the pole piece in the whole direction, the capacity loss of the battery is small, the energy density loss of the battery is also small, and the use time is longer.

In the above embodiment, the hole distribution areas 1 and the non-hole areas 2 on the active material layer are alternately arranged along the length direction of the pole piece, that is, the hole distribution areas 1, the non-hole areas 2 and the hole distribution areas 1 … … are alternately arranged along the length direction of the pole piece, and one non-hole area 2 is arranged between any two adjacent hole distribution areas 1; the shape of each cloth hole area 1 is a belt, the width of each cloth hole area 1 is the same as that of the pole piece, the length a of each cloth hole area 1 is 1-5 mm, and preferably, the length a of each cloth hole area 1 is 3 mm; the distance between any two adjacent cloth hole areas 1 is 40-60 mm, namely the length b of the non-hole area 2 between any two adjacent cloth hole areas 1 is 40-60 mm, and preferably, the distance between any two adjacent cloth hole areas 1 is 50 mm. Therefore, the length of the cloth hole region 1 and the distance between two adjacent cloth hole regions 1 are set in a proper range, so that the capacity loss of the battery can be further reduced on the basis of improving the porosity of the pole piece and the liquid retention of the pole piece.

In the above embodiment, the cloth hole region 1 is provided with a plurality of hole structures, and the hole structures can be distinguished by naked eyes, that is, the hole structures can be sensed by eyes or by means of a common magnifier; these pore structures are distributed in a regular shape to form a pore area, for example: the pore structures are distributed in regular shapes such as circles, triangles, rectangles, pentagons, hexagons or rhombuses to form the pore distribution area 1. Therefore, the pore structures are distributed in a regular shape to form the pore distribution area 1 instead of being distributed in disorder, so that the porosity on the pole piece is more uniform, the diffusion distance of lithium ions is further reduced, and the cycle performance and the rate performance of the battery are improved.

On the basis of the above embodiment, as shown in fig. 2, the plurality of hole structures are distributed in a rectangular matrix, and the distance c between any two adjacent hole structures in the hole distribution area 1 is 80-120 μm, and preferably, the distance c between any two adjacent hole structures in the hole distribution area 1 is 100 μm. Therefore, the plurality of hole structures are distributed in a rectangular matrix, so that the cycle performance and the rate performance of the battery are improved; the distance between the pore structures is in a certain range, and a certain shrinkage space is reserved between powder materials in the active material layer, so that the falling of active materials in the pore structure area on the pole piece can be reduced.

On the basis of the embodiment, the pore structure is a blind hole, namely a non-through hole, so that the situation that powder is loosened in a local area of the active material layer due to the fact that the pore structure is too deep, the bonding force is reduced, and side effects are generated on the performance of the battery can be avoided. On the basis of the above-described embodiment, the depth of the pore structure is one third to two thirds of the thickness of the active material layer, and preferably, the depth of the pore structure is one third of the thickness of the active material layer.

The depth of the pore structure is one third to two thirds of the thickness of the active material layer, relative to the thickness of the active material layer on the one-side surface of the current collector, that is, the depth of the pore structure is one third to two thirds of the thickness of the one-side active material layer.

On the basis of the embodiment, the pore diameters of the plurality of pore structures are the same, so that the cycle performance and the rate performance of the battery are improved. In addition to the above embodiments, the pore diameter of the pore structure is 10 to 20 μm, preferably 15 μm. Therefore, the powder falling off in the active material layer can be further reduced on the basis of improving the cycle performance and rate performance of the battery, and the subsequent processing performance and safety performance of the electrode are influenced.

The pole piece comprises a double-sided pole piece and a single-sided pole piece, wherein the double-sided pole piece is formed by coating active substance layers on the surfaces of two sides of the current collector, and the single-sided pole piece is formed by coating the active substance layer on the surface of one side of the current collector. If the electrode is a single-sided electrode piece, a plurality of hole distribution areas 1 and a plurality of hole-free areas 2 which are alternately arranged at intervals along the length direction of the electrode piece are arranged on an active substance layer of the single-sided electrode piece; if the electrode plate is a double-sided electrode plate, a plurality of cloth hole areas 1 and a plurality of non-hole areas 2 which are alternately arranged along the length direction of the electrode plate can be arranged on one active material layer of the double-sided electrode plate, or a plurality of cloth hole areas 1 and a plurality of non-hole areas 2 which are alternately arranged along the length direction of the electrode plate can be arranged on two active materials of the double-sided electrode plate. On the basis of the above embodiment, the pole piece is a double-sided pole piece, that is, both surfaces of the current collector are provided with active material layers, and both active material layers are provided with a cloth hole area 1 and a non-hole area 2. Therefore, the liquid retaining amount of the pole piece can be further increased, the cycle performance and the rate performance of the battery can be improved, and the capacity of the battery can be improved.

It should be noted that, if the active material layers on the two side surfaces of the double-sided pole piece are both provided with the hole area 1 and the non-hole area 2, the hole areas 1 on the two side surfaces may be in the same position, or may be arranged in a staggered manner along the length direction of the pole piece, that is, the hole areas 1 of the double-sided pole piece may be on two opposite sides of the current collector in the same position, or on two opposite sides of the current collector in different positions.

In addition to the above-described embodiments, the active material layer is perforated by a metal needle or laser perforation to form the perforated region 1. The pole piece can be a positive pole piece or a negative pole piece; the positive plate is punched before rolling, the positive plate is loose before rolling, the punching difficulty before rolling is low, and the consumed energy is low, so that the active material layer of the positive plate is punched in a metal needle mode before rolling. The negative pole piece punches after the roll-in, and the negative pole piece after the roll-in is more closely knit, and the degree of difficulty that the metal needle punched and the energy of consumption are more, and the negative pole piece thickness can reduce after the roll-in, consequently, after the roll-in, punches on the active material layer of negative pole piece through the mode that laser punched. In addition, the positive plate is perforated by a metal needle, and the negative plate is perforated by a laser perforation method, so that the falling of powder in the positive active material layer and the negative active material layer can be further reduced.

In one example of the present application, a positive electrode sheet is prepared by the following method:

selecting a double-sided pole piece as a positive pole piece;

punching a positive active material layer on one side surface of a positive plate by using 15-micrometer metal to form a cloth hole area 1, wherein the cloth hole area 1 and a non-hole area 2 are alternately arranged along the length direction of the positive plate at intervals, the length of each cloth hole area 1 is 3mm, and the distance between any two adjacent cloth hole areas 1 is 50 mm; the depth of the pore structure is one third of the thickness of the single-side anode active material layer, the pore structure is a blind hole and does not pierce through a current collector, the pore structure on the distribution hole area 1 is distributed in a rectangular matrix, the distance between any two adjacent pore structures is 100 micrometers, and each 30 groups of matrixes form a distribution hole area 1; vacuum dust collection is synchronously carried out in the punching process to complete punching of the first side;

and (3) perforating the positive active material layer on the other side surface of the positive plate according to the method, and rolling after perforation is finished to obtain the positive plate.

In one example of the present application, the negative electrode sheet is prepared by the following method:

selecting a double-sided pole piece as a negative pole piece;

after the rolling of the negative plate is finished, punching the negative active material layer on the surface of one side of the negative plate in a laser punching mode to form a cloth hole area 1, wherein the cloth hole area 1 and the non-hole area 2 are alternately arranged at intervals, the length of each cloth hole area 1 is 3mm, and the distance between any two adjacent cloth hole areas 1 is 50 mm; the depth of the pore structure is one third of the thickness of the single-side negative active material layer, the pore structure is a blind hole and does not pierce through a current collector, the pore diameter of each pore structure is 15 micrometers, the pore structures on the distribution pore region 1 are distributed in a rectangular matrix or a hexagonal matrix, the distance between any two adjacent pore structures is 100 micrometers, and each 30 groups of matrixes form the distribution pore region 1; vacuum dust collection is synchronously carried out in the punching process to complete punching of the first side;

and (3) perforating the negative active material layer on the other side surface of the negative plate according to the method, and obtaining the negative plate after completing perforation.

The second aspect of the present embodiment also provides a battery including an electrode assembly, an electrolyte, and a case, a housing cavity being formed inside the case, the electrode assembly and the electrolyte being located inside the housing cavity, and the electrode assembly and the electrolyte being enclosed inside the case; the electrode assembly comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate, wherein a positive tab is arranged on the positive plate, a negative tab is arranged on the negative plate, and the positive plate and/or the negative plate are/is the electrode plates.

And winding the positive plate, the diaphragm and the negative plate to form a winding core, putting the winding core into an accommodating cavity in the shell, injecting electrolyte, and forming, packaging and sorting to obtain the battery.

The cycle performance of the battery was tested as follows: testing 3 identical batteries at a constant temperature of 25 ℃, wherein each battery is discharged to 3V at a normal cycle of 0.7C, and discharged to 3V at a cycle of 0.2C for 100 times, and calibrating the discharge capacity of the battery core; and ending the circulation until the circulation is continued for 1000 times, or the 0.2C discharge capacity is less than 80 percent of the initial 0.2C discharge capacity. A cycle test result chart of the battery made of the pole piece in the example of the present application as shown in fig. 3 was obtained.

As can be seen from fig. 3, after the battery manufactured by using the pole piece of the embodiment of the present application is cycled for 1000 times, the capacity fading of the three batteries is less than 6%, which indicates that the pole piece provided by the embodiment improves the porosity of the pole piece, improves the liquid retention amount, can also greatly reduce the diffusion distance of lithium ions, and improves the cycle performance and the rate performance of the battery; in addition, the capacity loss of the battery is small, the energy density loss of the battery is also small, and the service life is longer.

Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.

Claims (10)

1. The utility model provides a pole piece, includes the mass flow body and sets up the active material layer of at least one side surface of mass flow body, its characterized in that, at least one the active material layer is including the cloth hole region that sets up the pore structure and the pore-free region that does not set up the pore structure, the cloth hole region with the pore-free region is followed the length direction of pole piece is interval setting in turn on the active material layer.

2. The pole piece of claim 1, wherein the length of the cloth hole area is 1-5 mm.

3. The pole piece according to claim 1, wherein the distance between any two adjacent cloth hole areas is 40-60 mm.

4. The pole piece of claim 1, wherein the hole area is provided with a plurality of the hole structures, and the hole structures are distributed in a regular shape.

5. The pole piece according to claim 4, wherein a plurality of the hole structures are distributed in a rectangular matrix, and the distance between any two adjacent hole structures is 80-120 μm.

6. The pole piece of claim 1 wherein the hole feature is a blind hole.

7. The pole piece according to claim 1 or 6, characterized in that the depth of the hole structure is one third to two thirds of the thickness of the active material layer.

8. The pole piece of claim 1, wherein the pore structure has a pore diameter of 10-20 μm.

9. The pole piece according to claim 1, characterized in that both lateral surfaces of the current collector are provided with said active substance layers, both of which are provided with a perforated area and a non-perforated area.

10. The battery is characterized by comprising a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate, wherein a positive tab is arranged on the positive plate, and a negative tab is arranged on the negative plate; the positive electrode tab and/or the negative electrode tab is the tab of any one of claims 1 to 9.

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