CN221201206U - Cathode sheet and battery core - Google Patents

Abstract

The utility model discloses a cathode sheet and a battery cell. The cathode sheet comprises a current collector, wherein the current collector is provided with a coating area, the coating area comprises a first area and a second area, and the second area is coated on the periphery of the first area; a first coating is applied to the first region; a second coating is applied to the second region, the second coating having a conductivity that is lower than the conductivity of the current collector. The second area is coated on the periphery of the first area, the first coating is coated on the first area, the second coating is coated on the second area, the second coating is enabled to be closer to the edge of the current collector compared with the first coating, meanwhile, the conductivity of the second coating is lower than that of the current collector, the resistance of a pole piece located in the second area is increased, the current is reduced, the polarization is increased, the lithium intercalation amount of the second area is reduced, the lithium ion intercalation rate of each area of the negative pole piece is uniform, and the safety is improved while the service life of the battery cell is prolonged.

Description

Cathode sheet and battery core

Technical Field

The utility model relates to the technical field of lithium ion batteries, in particular to a cathode sheet and an electric core.

Background

In the related art, due to the existence of the point discharge effect and the like charge repulsion effect, the current density of the edges of the positive pole piece and the negative pole piece of the battery cell is higher than that of the middle area in the charge and discharge process, and the lithium intercalation rate and the lithium intercalation quantity of the edges of the negative pole piece are higher than those of the middle position, so that the possibility of lithium precipitation phenomenon at the edges of the negative pole piece is higher, and the service life and the safety performance of the battery cell are influenced.

Disclosure of utility model

The present utility model aims to solve at least one of the technical problems existing in the prior art. Therefore, the utility model provides the cathode sheet, which can reduce the embedding rate and the embedding amount of the lithium ions at the edge and improve the service life and the safety performance of the battery cell when being applied to the battery cell.

The utility model also provides a battery cell with the cathode sheet.

The utility model also provides another battery cell with the cathode sheet.

The cathode sheet according to an embodiment of the first aspect of the present utility model includes:

The current collector is provided with a coating area, wherein the coating area comprises a first area and a second area, and the second area is coated on the periphery of the first area;

A first coating applied to the first region;

And the second coating is coated on the second area, and the conductivity of the second coating is lower than that of the current collector.

The cathode sheet according to the embodiment of the utility model has at least the following beneficial effects: the second area is coated on the periphery of the first area, the first coating is coated on the first area, the second coating is coated on the second area, the second coating is enabled to be closer to the edge of the current collector compared with the first coating, meanwhile, the conductivity of the second coating is lower than that of the current collector, the resistance of a pole piece located in the second area is increased, the electronic conductivity is reduced, the current is reduced, the polarization is increased, the lithium intercalation rate of a corresponding negative electrode in the second area is reduced, the lithium intercalation amount is reduced, and accordingly the lithium ion intercalation rate and the lithium ion intercalation amount of the corresponding whole negative electrode interface are relatively uniform, the service life of the battery core is prolonged, and the safety is improved.

According to some embodiments of the utility model, the second coating has a first edge closer to the first coating and a second edge further from the first coating, the thickness of the second coating gradually decreasing from the first edge toward the second edge.

According to some embodiments of the utility model, the current collector has a dimension D in the width direction of 10mm +.d +.2000 mm, the second coating has a first edge closer to the first coating and a second edge farther from the first coating, the dimension between the first edge and the second edge being 0.5mm to 0.2D.

According to some embodiments of the utility model, the second coating has a conductivity of 17MS/m to 32MS/m.

According to some embodiments of the utility model, the thickness of the second coating layer is 0.2 μm to 3 μm along the thickness direction of the current collector.

According to some embodiments of the utility model, the cathode sheet further comprises a tab, the current collector is further provided with a hollow foil region, the hollow foil region is arranged adjacent to the coating region, or the coating region is coated on the periphery of the hollow foil region, the tab is connected to the hollow foil region, the hollow foil region is located at the end or the middle of the current collector along the length direction, and a part of the second coating is wound on the periphery of the hollow foil region.

According to some embodiments of the utility model, the cathode sheet further includes a third coating layer coated on the second coating layer, and a sum of sizes of the second coating layer and the third coating layer is greater than or equal to a size of the first coating layer in a thickness direction of the current collector.

According to some embodiments of the utility model, the number of the first coating layers and the second coating layers is two, and one first coating layer and one second coating layer are respectively attached to two sides of the current collector along the thickness direction of the current collector.

A cell according to an embodiment of the second aspect of the present utility model includes:

anode plates;

The cathode sheet provided in the embodiment of the first aspect;

And the diaphragm is arranged between the anode sheet and the cathode sheet, and the anode sheet, the diaphragm and the cathode sheet are wound to form the battery cell.

The battery cell according to the embodiment of the second aspect of the utility model has at least the following beneficial effects: the battery cell comprises the cathode plate provided by the embodiment of the first aspect, and at least has all the advantages of the cathode plate, so that the uniformity of the lithium ion intercalation/deintercalation rate of each part of the cathode plate in the charge and discharge process is improved, and the service life of the battery cell is prolonged and the safety is improved.

According to an embodiment of the third aspect of the present utility model, a battery cell includes:

A plurality of anode sheets;

A plurality of cathode sheets provided in the embodiment of the first aspect, wherein the anode sheets and the cathode sheets are stacked and alternately arranged;

And the diaphragms are arranged between the adjacent anode sheets and the cathode sheets.

According to the embodiment of the third aspect of the utility model, the battery cell has at least the following beneficial effects: the battery cell comprises the cathode plate provided by the embodiment of the first aspect, and at least has all the advantages of the cathode plate, so that the uniformity of the lithium ion intercalation/deintercalation rate of each part of the cathode plate in the charge and discharge process is improved, and the service life of the battery cell is prolonged and the safety is improved.

Additional aspects and advantages of the utility model will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model.

Drawings

The utility model is further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic view of a cathode sheet when an electrical core of an embodiment of the present utility model is a wound structure;

FIG. 2 is a cross-sectional view of a cathode sheet according to an embodiment of the present utility model;

FIG. 3 is a schematic view of a cathode sheet with an empty foil area in the middle position according to an embodiment of the present utility model;

Fig. 4 is a schematic diagram of a cathode sheet when the battery cell is in a lamination structure according to an embodiment of the present utility model.

Reference numerals:

A current collector 100, a first region 110, a second region 120, an empty foil region 130;

First coating 200, second coating 300, first edge 310, second edge 320;

A third coating 400, and a tab 500.

Detailed Description

Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the utility model.

In the description of the present utility model, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present utility model and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present utility model.

In the description of the present utility model, the meaning of a number is one or more, the meaning of a number is two or more, and greater than, less than, exceeding, etc. are understood to exclude the present number, and the meaning of a number is understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present utility model, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present utility model can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

In the description of the present utility model, the descriptions of the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. 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 the existing lithium ion battery, due to the existence of a point discharge effect and a like charge repulsion effect, the current density of the edges of the positive pole piece and the negative pole piece of the battery core is higher than that of the middle area in the charge and discharge process, and the lithium intercalation rate and the lithium intercalation quantity of the edges of the negative pole piece are higher than those of the middle position, so that the possibility of lithium precipitation phenomenon at the edges of the negative pole piece is higher. Meanwhile, when the battery cell is used in a low-temperature environment, the temperature of the edge of the pole piece is lower than that of the middle area, the system dynamics performance is insufficient due to the low temperature of the edge of the negative pole, and the risk of lithium precipitation of the cathode piece is further improved.

To solve at least one of the above problems, referring to fig. 1 to 4, an embodiment of a first aspect of the present utility model provides a cathode sheet including a current collector 100, a first coating layer 200, and a second coating layer 300. The current collector 100 has a set length direction, a width direction and a thickness direction, the current collector 100 is provided with a coating area, the coating area comprises a first area 110 and a second area 120, and the second area 120 is coated on the periphery of the first area 110; the first coating 200 is applied to the first region 110; the second coating 300 is applied to the second region 120, and the conductivity of the second coating 300 is lower than that of the current collector 100. Wherein the conductivity of the second coating 300 and the conductivity of the current collector 100 may be measured by existing means, for example using a conductivity tester.

The second region 120 is coated on the periphery of the first region 110, the first coating 200 is coated on the first region 110, the second coating 300 is coated on the second region 120, so that the second coating 300 is closer to the edge of the current collector 100 than the first coating 200, meanwhile, the conductivity of the second coating 300 is lower than that of the current collector 100, the resistance of the electrode plate at the second region 120 is increased, the electronic conductivity is reduced, the polarization is increased while the current is reduced, the lithium intercalation amount of the corresponding negative electrode of the second region 120 is reduced, and therefore, the intercalation rate and the intercalation amount of lithium ions of the whole negative electrode interface of the negative electrode plate are relatively uniform. Meanwhile, as the resistance value of the second region 120 increases, the discharge temperature rise when the current flows through the second coating 300 increases, thereby improving the kinetic performance of lithium ion intercalation in the region, reducing the risk of lithium precipitation and safety accidents caused by low temperature, and improving the safety while prolonging the service life of the battery cell.

Referring to fig. 2, the dashed lines in fig. 2 are provided to facilitate distinguishing between the various coatings and are not to be understood as having a distinct parting line or outline directly from each other. In some embodiments, the cathode sheet further includes a third coating 400, the third coating 400 being coated on the second coating 300, and a sum of sizes of the second coating 300 and the third coating 400 being greater than or equal to a size of the first coating 200 in a thickness direction of the current collector 100. The composition of the third coating 400 may be the same as that of the first coating 200, the second coating 300 and the third coating 400 are active material layers, when the cathode sheet is manufactured, the second coating 300 is first coated on the second region 120, if the compositions of the first coating 200 and the third coating 400 are identical, the second coating 300 and the third coating 400 may be coated at one time, and since the thickness of the second coating 300 is smaller, the sum of the dimensions of the second coating 300 and the third coating 400 is close to the dimension of the first coating 200 in the thickness direction of the current collector 100, and the influence on the flatness of the outer surface of the cathode sheet may be negligible.

In some embodiments, the second coating 300 may be a conductive gel coating, a nano-coating of a ceramic and conductive agent mixture, or a lithium iron phosphate coating. The conductive adhesive coating can be gold conductive adhesive, silver conductive adhesive, copper conductive adhesive, carbon nanotube conductive adhesive and the like; when a nano-coating formed by mixing ceramic and a conductive agent is selected as the second coating 300, the conductive agent may be selected from graphite, conductive carbon black, conductive carbon nanotubes, graphene, and the like, and the nano-coating generally further comprises an adhesive, and the conductivity is adjusted by adjusting the components of the conductive agent, the ceramic, and the adhesive.

It should be noted that the conductivity of the coating is also determined after the mass percentages of the coating components and individual components are determined, irrespective of the thickness of the coating. For example, when a conductive paste is used as the second coating layer 300, the adjustment of the conductivity can be achieved by adjusting the mass percentage of the conductive element therein, such as the mass percentage of gold, silver, or copper; when a nano-coating formed by mixing ceramic and a conductive agent is used as the second coating 300, the conductivity is adjusted by selecting the type of the conductive agent and adjusting the mass percentage of the conductive agent.

In some embodiments, the second coating 300 has a first edge 310 proximate to the first coating 200, and a second edge 320 distal from the first coating 200, the first edge 310 defining the first region 110, the second coating 300 having a thickness that gradually decreases from the second edge 320 toward the first edge 310. The closer to the edge of the current collector 100, the greater the current density during charging and discharging, the greater the resistance of the resistor to be increased at the edge of the current collector 100, the greater the thickness of the second coating 300 to be coated, and the smaller the resistance of the current collector 100 from the edge of the current collector 100 to the middle part, the smaller the thickness of the second coating 300, so as to achieve the effect of balancing the current densities at each part of the pole piece.

Referring to FIG. 2, in some embodiments, current collector 100 has a dimension D in the width direction of 10 mm.ltoreq.D.ltoreq.2000 mm, and second coating 300 has a first edge 310 that is closer to first coating 200 and a second edge 320 that is farther from first coating 200, the dimension between first edge 310 and second edge 320 being 0.5mm to 0.2D. For example, when the width of the current collector 100 is 40mm, the dimension between the first edge 310 and the second edge 320 is 0.5mm to 8mm, and the dimension can be selected from the above numerical ranges according to practical situations, so as to satisfy the effect of reducing the current density of the corresponding region of the pole piece and balancing the current density of each part of the pole piece.

In some embodiments, the second coating 300 has a conductivity of 17MS/m to 32MS/m. The conductivity of the second coating 300 is approximately 50% to 90% of the conductivity of the current collector 100. The current collector 100 may alternatively be made of aluminum. Electrons are introduced into the third coating 400 from the current collector 100 of the second region 120 through the second coating 300 and enter the third coating 400, and since the conductivity of the second coating 300 is less than that of the current collector 100, the blocking of electrons as they pass through the second coating 300 increases, the rate at which electrons pass through the second coating 300 decreases, and thus the rate at which lithium ions are inserted into the third coating 400 and gain electrons decreases, and the uniformity of the rate at which lithium ions are inserted into the third coating 400 and the rate at which lithium ions are inserted into the first coating 200 increases.

Specifically, the conductivity of the second coating 300 may be selected to be any other value among 17MS/m, 18MS/m, 20MS/m, 23MS/m, 25MS/m, 28MS/m, 30MS/m, 32MS/m, and 17MS/m to 32 MS/m.

In some embodiments, the thickness of the second coating 300 is 0.2 μm to 3 μm in the thickness direction. The coating thickness of the second coating layer 300 depends on the electrical conductivity of the second coating layer 300, and the lower the electrical conductivity of the second coating layer 300, the thinner the second coating layer 300, provided that the resistance value of the required increase resistance is the same. Specifically, the thickness of the second coating layer 300 may be selected to be any other value among 0.2 μm, 0.5 μm, 0.8 μm, 1.0 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, and 0.2 μm to 3 μm.

Referring to fig. 1, 3 and 4, in some embodiments, the cathode sheet further includes a tab 500, the current collector 100 is further provided with an empty foil region 130, the empty foil region 130 is disposed adjacent to the coating region, or the coating region is coated on the outer circumference of the empty foil region 130, the tab 500 is connected to the empty foil region 130, the empty foil region 130 is located at an end or a middle portion of the current collector 100 in the length direction, and a portion of the second coating 300 is wound around the outer circumference of the empty foil region 130. When the hollow foil region 130 is disposed at the middle portion of the current collector 100, the distance between the active material at each position on the cathode sheet and the tab 500 is not too far, and the current can quickly reach each position of the sheet, thereby further improving the charge and discharge rate of the battery.

Referring to fig. 2, for convenience of illustration, the pole piece of fig. 2 illustrates only one side of the pole piece, and in some embodiments, the number of the first coating 200 and the second coating 300 is two, and one first coating 200 is respectively attached to both sides of the current collector 100, and one second coating 300 is respectively attached to both sides of the current collector 100 in the thickness direction of the current collector 100. The mirror image arrangement of each coating on both sides of the current collector 100 is performed, after the coating of the coating on one side in the thickness direction of the current collector 100 is completed, the coating on the other side is further performed, and then the processing operations such as rolling and the like are performed to complete the production and the manufacture of the cathode plate.

An embodiment of the second aspect of the present utility model provides a battery (not shown in the drawings), which includes an anode sheet, a separator, and the cathode sheet provided in the embodiment of the first aspect. The diaphragm is arranged between the anode sheet and the cathode sheet, and the anode sheet, the diaphragm and the cathode sheet are wound to form a battery cell. Referring to fig. 1 and 3, fig. 1 and 3 are cathode sheets of a battery cell with a winding structure, and the battery cell includes the cathode sheets provided by the embodiment of the first aspect, and at least has all advantages of the cathode sheets, so that uniformity of lithium ion intercalation/deintercalation rates of each part of the cathode sheets in a charging and discharging process is improved, and thus, service life of the battery cell is prolonged and safety is improved.

An embodiment of a third aspect of the present utility model provides another electrical core, including a plurality of anode sheets, a plurality of separators, and a plurality of cathode sheets provided in the embodiment of the first aspect. The anode sheets and the cathode sheets are alternately stacked, and the diaphragm is arranged between the adjacent anode sheets and the adjacent cathode sheets. The battery cell of this embodiment is a lamination structure, referring to fig. 4, and fig. 4 is a cathode sheet of the lamination structure battery cell, where the battery cell includes the cathode sheet provided by the embodiment of the first aspect, and at least has all advantages of the cathode sheet, so that uniformity of lithium ion intercalation/deintercalation rates of each part of the positive and negative electrode sheets in the charge and discharge process is improved, thereby prolonging service life of the battery cell and improving safety.

The embodiments of the present utility model have been described in detail with reference to the accompanying drawings, but the present utility model is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present utility model. Furthermore, embodiments of the utility model and features of the embodiments may be combined with each other without conflict.

Claims (10)

1. A cathode sheet, comprising:

The current collector is provided with a coating area, wherein the coating area comprises a first area and a second area, and the second area is coated on the periphery of the first area;

A first coating applied to the first region;

And the second coating is coated on the second area, and the conductivity of the second coating is lower than that of the current collector.

2. The cathode sheet according to claim 1, wherein the second coating layer has a first edge closer to the first coating layer and a second edge away from the first coating layer, the thickness of the second coating layer gradually decreasing from the first edge toward the second edge.

3. The cathode sheet according to claim 1, wherein the current collector has a dimension D in a width direction of 10mm +.d+. 2000mm, the second coating has a first edge closer to the first coating and a second edge farther from the first coating, and a dimension between the first edge and the second edge is 0.5mm to 0.2D.

4. The cathode sheet according to claim 1, wherein the second coating layer has an electrical conductivity of 17MS/m to 32MS/m.

5. The cathode sheet according to claim 1, wherein the thickness of the second coating layer is 0.2 μm to 3 μm in the thickness direction of the current collector.

6. The cathode sheet according to claim 1, further comprising a tab, wherein the current collector is further provided with an empty foil region, wherein the empty foil region is disposed adjacent to the coating region, or wherein the coating region is coated on the outer periphery of the empty foil region, wherein the tab is connected to the empty foil region, wherein the empty foil region is located at an end or a middle portion of the current collector in a length direction, and wherein a portion of the second coating is wound around the outer periphery of the empty foil region.

7. The cathode sheet according to any one of claims 1 to 6, further comprising a third coating layer coated on the second coating layer, wherein a sum of dimensions of the second coating layer and the third coating layer is greater than or equal to a dimension of the first coating layer in a thickness direction of the current collector.

8. The cathode sheet according to any one of claims 1 to 6, wherein the number of the first coating layers and the number of the second coating layers are two, and one first coating layer is respectively attached to each of both sides of the current collector, and one second coating layer is respectively attached to each of both sides of the current collector in a thickness direction of the current collector.

9. The electric core, its characterized in that includes:

anode plates;

the cathode sheet according to any one of claims 1 to 8;

And the diaphragm is arranged between the anode sheet and the cathode sheet, and the anode sheet, the diaphragm and the cathode sheet are wound to form the battery cell.

10. The electric core, its characterized in that includes:

A plurality of anode sheets;

A plurality of the cathode sheets according to any one of claims 1 to 8, the anode sheets being stacked alternately with the cathode sheets;

And the diaphragms are arranged between the adjacent anode sheets and the cathode sheets.