CN112701247B

CN112701247B - Negative plate, battery roll core and battery

Info

Publication number: CN112701247B
Application number: CN202011594564.4A
Authority: CN
Inventors: 赵君义; 邹浒
Original assignee: Zhuhai Cosmx Battery Co Ltd
Current assignee: Zhuhai Cosmx Battery Co Ltd
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-02-01
Anticipated expiration: 2040-12-29
Also published as: CN112701247A

Abstract

The application discloses negative plate, battery roll core and battery belongs to the technical field of batteries. The negative plate comprises: the current collector comprises a first surface and a second surface which are arranged oppositely, the first surface comprises a first area and a second area, the second surface comprises a third area and a fourth area, the third area corresponding to the first area is arranged, and the second area corresponding to the fourth area is arranged; the first region and the third region are provided with the adhesive layer, and the second region and the fourth region are provided with the active material layer. Therefore, the phenomena of wrinkling and folding of the current collector in the winding process of the negative plate can be reduced.

Description

Negative plate, battery roll core and battery

Technical Field

The application belongs to the technical field of batteries, and particularly relates to a negative plate, a battery roll core and a battery.

Background

At present, at positive plate and negative pole piece coiling folding formation book core's in-process, only have the single face to scribble the district because the one end of the mass flow body of negative pole piece that sets up the utmost point ear, only have the single face to be equipped with negative pole active material layer promptly, lead to rolling up the core and can appear the fold under the hot pressing, and then make near the negative pole active material of fold district normally participate in chemical reaction, still can lead to rolling up the core and appear the safety risk when serious.

It can be seen that, in the related art, the negative electrode sheet is prone to wrinkle during the winding process.

Disclosure of Invention

The application aims at providing a negative pole piece, a battery roll core and a battery, and can solve the problem that wrinkles easily appear in the winding process of the negative pole piece in the related technology.

In order to solve the technical problem, the present application is implemented as follows:

in a first aspect, an embodiment of the present application provides a negative electrode sheet, including: the current collector comprises a first surface and a second surface which are arranged oppositely, the first surface comprises a first area and a second area, the second surface comprises a third area and a fourth area, the third area corresponding to the first area is arranged, and the second area corresponding to the fourth area is arranged;

the first region and the third region are provided with the adhesive layer, and the second region and the fourth region are provided with the active material layer.

Optionally, in the case that the adhesive layer is formed in the first region and the third region by coating, a thickness of the adhesive layer is 1 to 5 micrometers.

Optionally, in the case that the adhesive layer is formed in the first region and the third region by bonding, a thickness of the adhesive layer is 1 to 10 micrometers.

Optionally, the adhesive layer is prepared based on a soluble material and an emulsifier, wherein the soluble material accounts for 94% -97.5%, and the emulsifier accounts for 2.5% -6%.

Optionally, the soluble material includes butyl acrylate and methyl acrylate, and the emulsifier includes at least one of carboxylate, sulfate, and sulfonate.

Optionally, an area of the third region is larger than an area of the first region, and a portion of the third region beyond the first region is disposed corresponding to the second region.

Optionally, the current collector further comprises a tab, wherein the tab is disposed in the first region and electrically connected to the current collector.

Optionally, one end of the current collector, which is far away from the tab, further includes a fifth area disposed on the first surface and a sixth area disposed on the second surface, and the fifth area is disposed corresponding to the sixth area;

wherein the fifth area and the sixth area are both provided with the glue layer.

In a second aspect, an embodiment of the present application further provides a battery winding core, including the negative electrode tab of the first aspect, the first region is located inside the battery winding core, and the fifth region is located outside the battery winding core.

In a third aspect, an embodiment of the present application further provides a battery, which includes an electrolyte and the battery roll core of the second aspect, and the glue layer is soluble in the electrolyte.

In the embodiment of this application, set up the glue film through the first region and the third region at the mass flow body, can improve the regional structural strength that does not set up active material layer of the mass flow body, can be in order to improve the first region and the regional structural strength of third of the mass flow body, and at the coiling in-process of negative pole piece, the glue film can also provide stress compensation to reduce the phenomenon that fold, discount appear in the mass flow body of negative pole piece in coiling.

Additional aspects and advantages of the present application 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 present application.

Drawings

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

fig. 1 is one of schematic structural diagrams of a negative electrode sheet provided in an embodiment of the present application;

fig. 2a is a schematic structural diagram of a current collector provided in an embodiment of the present application;

fig. 2b is a second schematic structural diagram of a negative electrode sheet provided in the embodiment of the present application;

fig. 3 is a flowchart of a method for preparing a negative electrode sheet provided in an embodiment of the present application;

FIG. 4 is a schematic view of the application of a glue layer provided in the embodiments of the present application;

fig. 5 is a schematic diagram of adhesion of a glue layer provided in an embodiment of the present application.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The features of the terms first and second in the description and in the claims of the present application may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specified. In addition, "and/or" in the specification and claims means at least one of connected objects, a character "/" generally means that a preceding and succeeding related objects are in an "or" relationship.

As shown in fig. 1 and 2a, an embodiment of the present application provides a negative electrode sheet, including: the current collector 10 comprises a first surface 11 and a second surface 12 which are arranged oppositely, the first surface 11 comprises a first area 111 and a second area 112, the second surface 12 comprises a third area 121 and a fourth area 122, the first area 111 is arranged corresponding to the third area 121, and the second area 112 is arranged corresponding to the fourth area 122;

the first region 111 and the third region 121 are provided with the glue layer 30, and the second region 112 and the fourth region 122 are provided with the active material layer 20.

In this embodiment, by providing the glue layer 30 in the first region 111 and the third region 121 of the current collector 10, the structural strength of the region of the current collector 10 where the active material layer 20 is not provided may be improved, that is, the structural strength of the first region 111 and the third region 121 of the current collector 10 may be improved, and in the winding process of the negative electrode sheet, the glue layer 30 may also provide stress compensation, and reduce the phenomenon that the negative electrode sheet folds and folds in the current collector 10 in the winding process.

The first region 111 is disposed corresponding to the third region 121, and the second region 112 is disposed corresponding to the fourth region 122, which means that at least two regions disposed correspondingly overlap each other in the thickness direction of the current collector 10.

In an embodiment, the area of the first region 111 is smaller than that of the third region 121, and the area of the second region 112 is larger than that of the fourth region 122, that is, the portion of the third region 121 beyond the first region 111 may be disposed corresponding to the second region 112. And by arranging the glue layer 30 in the third area 121, the structural strength of the current collector 10 in the third area 121 can be improved, and the probability that the negative electrode sheet folds in the winding process of the current collector 10 is reduced.

Alternatively, current collector 10 may be a copper foil, i.e., current collector 10 may be a foil made of a copper material.

Alternatively, the active material layer 20 may be a mixture of a combination of a negative electrode active material, a conductive agent, and a binder.

Wherein, the proportion of the negative active material is 90-98.5%, the proportion of the conductive agent is 0-5%, and the proportion of the adhesive is 0-5%.

For example, the active material layer 20 may be prepared using a mixture of 96.5% graphite, 0.5% conductive agent, and 3% binder.

Optionally, the adhesive layer 30 is prepared based on a soluble material and an emulsifier, wherein the soluble material is 94-97.5% by weight, and the emulsifier is 2.5-6% by weight.

Specifically, the main components of the soluble material comprise butyl acrylate and methyl acrylate, and the main components of the emulsifier comprise carboxylate, sulfate, sulfonate and the like.

In this embodiment, glue film 30 through adopting soluble material and emulsifier preparation to obtain can dissolve in the electrolyte of battery to make the thickness of the battery roll core based on negative pole piece preparation in this application can not appear obviously increasing, the thickness proportion of battery roll core can not appear obviously changing promptly, thereby realized under the condition that does not increase the size of battery roll core, the phenomenon of fold, discount appear in the mass flow body 10 of having avoided the negative pole piece, and improved the security that the battery rolled the core.

Optionally, the negative electrode tab further includes a tab (not shown), which is disposed in the first region 111 and electrically connected to the current collector 10.

In the present embodiment, the tab may be electrically connected to the current collector 10 by heat fusion or welding.

The adhesive layer 30 may be disposed on the first region 111 and the third region 121 of the current collector 10 by coating or bonding.

In addition, the tab and the current collector 10 may also be an integrated structure, and the tab may protrude from the body structure of the current collector 10.

Wherein, in the case of forming the glue layer 30 in the first region 111 and the third region 121 by means of coating, the thickness of the glue layer 30 is 1 to 5 micrometers; in the case where the adhesive layer 30 is formed in the first region 111 and the third region 121 by bonding, the thickness of the adhesive layer 30 is 1 to 10 micrometers; that is, when the adhesive layer 30 is arranged in an adhesive manner, the adhesive layer with a larger thickness can be selected to improve the adhesive strength of the adhesive layer 30; the adhesive layer 30 formed on the first region 111 and the third region 121 can be more uniform due to the coating manner, so that the adhesive layer 30 can be coated a little thinner to reduce the material of the adhesive layer 30 and reduce the manufacturing cost of the negative electrode plate.

As shown in fig. 2b, the end of the current collector 10 away from the tab further includes a fifth region (not shown) disposed on the first surface 11 and a sixth region (not shown) disposed on the second surface 12, and the fifth region is disposed opposite to the sixth region, wherein the fifth region and the second region are both provided with the glue layer 30. The adhesive layer 30 is disposed at the other end of the current collector 10, i.e., the end far away from the tab of the current collector 10, so that the structural strength of the current collector 10 can be further improved.

The embodiment of the application also provides a battery winding core, which comprises the negative plate shown in figures 1 and 2.

It should be noted that, the implementation manner of the foregoing negative electrode sheet embodiment is also applicable to the embodiment of the battery winding core, and can achieve the same technical effect, and details are not repeated herein.

The first area is located inside the battery roll core, and the fifth area is located outside the battery roll core.

The embodiment of the application also provides a battery, which comprises the electrolyte and the battery winding core, and the glue layer in the embodiment can be dissolved in the electrolyte.

In the formation process of manufacturing the battery, the adhesive layer arranged on the current collector of the negative plate can be dissolved in the electrolyte in a high-temperature environment, and a stable structure is formed and exists in the electrolyte, so that a coating with a new thickness cannot be formed on the surface of the current collector, and the electrolyte cannot reduce the capacity density of the battery core due to the dissolution of the adhesive layer; the thickness change of the battery roll core can not be caused, so that the phenomena of fold and folding of the current collector of the negative plate are avoided under the condition that the size of the battery roll core is not increased, and the safety of the battery is improved.

In addition, since the gel layer is soluble in the electrolyte, non-electrolyte components such as butyl acrylate and methyl acrylate can be detected in the electrolyte of the battery.

As shown in fig. 3, an embodiment of the present application further provides a method for preparing a negative electrode sheet, including:

step 301, a current collector is provided.

In this step, the current collector may be a copper foil, i.e., the current collector may be a foil made of a copper material

As shown in fig. 1, the current collector 10 includes a first surface 11 and a second surface 12 that are opposite to each other, the first surface 11 includes a first region 111 and a second region 112, the second surface 12 includes a third region 121 and a fourth region 122, the first region 111 is disposed corresponding to the third region 121, and the second region 112 is disposed corresponding to the fourth region 122.

Step 302, forming an active material layer in the second region and the fourth region.

In this step, the active material layer may be formed in the second region and the fourth region by means of coating.

In one embodiment, a mixture of 90-98.5% by mass of a common negative active material, 0-5% by mass of a conductive agent, and 0-5% by mass of a binder may be uniformly dispersed in an NMP (N-methylpyrrolidone) solvent to prepare a negative slurry; and the negative electrode slurry may be applied to the second and fourth regions of the current collector by means of coating and then baked so that the negative electrode slurry applied to the second and fourth regions forms active material layers.

The negative electrode slurry can be prepared by uniformly dispersing 96.5% of graphite, 0.5% of conductive agent and 3% of binder in NMP solvent. And the coating mode comprises extrusion coating, transfer coating, roll coating and the like.

Step 303, after the active material layer is formed, forming a glue layer in the first region and the third region.

In this step, a glue layer may be formed in the first region and the third region by coating or bonding.

Wherein, the glue layer is prepared based on soluble materials and an emulsifier.

And 304, after the glue layer is formed, arranging a tab electrically connected with the current collector in the first area, and obtaining a negative plate.

In this step, tabs electrically connected to the current collectors may be disposed in the first region by hot melting or welding, and a negative electrode plate is obtained.

The negative plate prepared by the negative plate preparation method provided by the embodiment of the application is arranged on the glue layers of the first area and the third area of the current collector, so that the structural strength of the area, not provided with the active material layer, of the current collector can be improved, the structural strength of the first area and the third area of the current collector can be improved, in the winding process of the negative plate, the glue layers can also provide stress compensation, and the phenomena that the current collector of the negative plate is wrinkled and folded in the winding process are reduced.

In one embodiment, the glue layer may be formed in the first region and the third region by a micro-gravure transfer coating method.

Firstly, mixing and stirring 40-50% of soluble material, 1-3% of emulsifier and 49-57% of plasma-removing water, and stirring to form an emulsion state; wherein the main components of the soluble material are butyl acrylate and methyl acrylate;

secondly, the prepared emulsion is subjected to micro-concave roller transfer coating to a first area and a third area of a current collector, and then is baked in an oven, wherein the baking temperature is 60-80 ℃, and the coating speed is 30-60 m/min, so that a glue layer with uniform double surfaces can be obtained;

and after the negative plate is prepared, the prepared negative plate is wound, packaged, baked, injected with liquid, aged and formed.

In the high-temperature environment of the formation process, the glue layer can be similar to and compatible with the electrolyte of the battery, can be completely dissolved in the electrolyte, and can detect the components of methyl acrylate and butyl acrylate in the electrolyte in which the glue layer is dissolved.

As shown in fig. 4, the micro-gravure roll transfer coating apparatus includes a negative plate unwinding part 401, a first coating head 402, a second coating head 403, an oven 404, and a negative plate winding part 405;

the negative plate unwinding part 401 and the negative plate winding part 405 are used for placing a negative plate, the oven 404 is used for baking the negative plate coated with the glue layer, the first coating head 402 is used for coating the glue layer on the first surface of the negative plate, and the second coating head 403 is used for coating the glue layer on the second surface of the negative plate.

In another embodiment, the adhesive layer may be applied to the first and third regions of the current collector of the negative electrode sheet by a winding machine. The winding machine is used for winding the positive plate, the negative plate and the diaphragm to manufacture the battery winding core.

As shown in fig. 5, the winding machine is used for winding the positive electrode sheet 501, the negative electrode sheet 502, and the separator 503 to produce a battery winding core, and during the winding process, the winding tape 504 can be used for pasting the negative electrode sheet 502 on both sides of the winding machine, and forming glue layers in the first region and the third region of the current collector of the negative electrode sheet 502.

The winding machine comprises a roller 505 for bearing the positive electrode sheet 501, the negative electrode sheet 502 and the diaphragm 503.

Through setting up the glue film in the first region and the third region of the mass flow body like this, can improve the regional structural strength of the active material layer that does not set up of the mass flow body, can be in order to improve the first region and the regional structural strength of third of the mass flow body, and at the coiling in-process of negative pole piece, the glue film can also provide stress compensation to reduce the phenomenon that fold, discount appear in the mass flow body of negative pole piece in coiling.

In the description herein, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like means 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 application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

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

Claims

1. A negative electrode sheet, comprising: the current collector comprises a first surface and a second surface which are arranged oppositely, the first surface comprises a first area and a second area, the second surface comprises a third area and a fourth area, the third area corresponding to the first area is arranged, and the second area corresponding to the fourth area is arranged;

the first area and the third area are provided with the adhesive layer, and the second area and the fourth area are provided with the active material layer;

the adhesive layer is composed of a soluble material and an emulsifier, the soluble material comprises butyl acrylate and methyl acrylate, and the emulsifier comprises at least one of carboxylate, sulfate and sulfonate.

2. The negative electrode sheet according to claim 1, wherein the thickness of the adhesive layer is 1 to 5 μm when the adhesive layer is formed in the first and third regions by coating.

3. The negative electrode sheet according to claim 1, wherein the thickness of the adhesive layer is 1 to 10 μm when the adhesive layer is formed in the first and third regions by bonding.

4. The negative electrode sheet according to any one of claims 1 to 3, wherein the soluble material is 94% to 97.5%, and the emulsifier is 2.5% to 6%.

5. The negative electrode sheet according to any one of claims 1 to 3, wherein the area of the third region is larger than the area of the first region, and a portion of the third region that exceeds the first region is provided corresponding to the second region.

6. The negative electrode sheet according to any one of claims 1 to 3, further comprising a tab provided in the first region and electrically connected to the current collector.

7. The negative electrode sheet according to claim 1, wherein one end of the current collector, which is far away from the first region, further comprises a fifth region arranged on the first surface and a sixth region arranged on the second surface, and the fifth region is arranged corresponding to the sixth region;

8. A battery comprising the negative electrode sheet according to any one of claims 1 to 7 and an electrolyte, wherein the adhesive layer is soluble in the electrolyte.