CN113451539B

CN113451539B - Preparation method of electrode plate, electrode plate and lithium ion battery

Info

Publication number: CN113451539B
Application number: CN202010795886.9A
Authority: CN
Inventors: 姜新军; 张小勇; 张剑; 姚芳
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2020-08-10
Filing date: 2020-08-10
Publication date: 2022-03-18
Anticipated expiration: 2040-08-10
Also published as: CN113451539A

Abstract

The embodiment of the application discloses a preparation method of an electrode plate, the electrode plate and a lithium ion battery. The method comprises the following steps: providing a current collector, wherein the current collector is provided with a tab preset area, and an isolating film is coated on the tab preset area; coating active material slurry on the current collector and the isolating film to form an active material film layer; removing the active substance film layer and the isolating film arranged in the preset region of the tab by using laser to form a concave groove; and arranging a tab in the sunken groove to form the electrode pole piece.

Description

Preparation method of electrode plate, electrode plate and lithium ion battery

Technical Field

The application relates to the technical field of batteries, in particular to a preparation method of an electrode plate, the electrode plate and a lithium ion battery.

Background

Since the commercial popularization of the lithium ion battery, the lithium ion battery has the advantages of high energy density, high working voltage, long cycle life, no memory effect, environmental protection, flexible design of size, shape and size according to actual requirements and the like, and is widely used as a power supply of various portable electronic appliances.

In order to improve the area utilization rate of a current collector of a lithium ion battery, in the prior art, a thermal expansion foaming pressure sensitive adhesive tape is pasted on the current collector, a high-temperature drying mode is adopted to enable thermal expansion foaming to be combined with an active material film layer to be separated from the current collector, and a tab is arranged in a separation area. But the gluing tolerance is large when the thermal expansion foaming pressure sensitive adhesive tape is pasted, so that the area occupied by the falling-off area and the area required by the connection of the pole lugs cannot be matched with each other.

Disclosure of Invention

An object of the application is to provide a new technical scheme of a preparation method of an electrode plate, so as to solve the technical problem that the area occupied by a falling area and the area required by tab connection cannot be matched with each other in the prior art.

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

in a first aspect, a method for preparing an electrode plate is provided. The method comprises the following steps:

s101, providing a current collector, wherein the current collector is provided with a lug preset area, and an isolating film is coated in the lug preset area;

s102, coating active substance slurry on the current collector and the isolating film to form an active substance film layer;

s103, removing the active material film layer and the isolating film arranged in the preset region of the tab by using laser to form a concave groove;

and S104, arranging a tab in the concave groove to form the electrode pole piece.

Optionally, the area of the preset region of the tab is larger than the area of the bottom of the depressed groove; the area of the bottom of the sunken groove is matched with the required area for connecting the tab.

Optionally, the thickness of the isolation film is in a range of 0.5 μm to 5 μm, and the thickness of the active material film layer is in a range of 40 μm to 80 μm.

Optionally, the material of the isolation film includes graphite.

Optionally, in step S103, when the active material film layer disposed in the tab preset region is removed by using laser, the active material film layer and the current collector are isolated by the isolation film.

Optionally, the preparation method of the electrode sheet further comprises: and rolling and splitting the current collector with the concave groove.

Optionally, in step S102, the active material slurry is dried to form the active material film layer, where the drying temperature is in a range of 90 ℃ to 130 ℃.

Alternatively, in step S102, the area of the active material film layer is at least 10 times the area of the separator film.

In a second aspect, an electrode tab is provided. The electrode sheet includes: the current collector, the isolating film and the active material film layer are arranged in a stacked mode;

the current collector forms the lug preset area, and part of the lug preset area is exposed out of the current collector;

the exposed current collector and the isolation film and the active material film layer define the concave groove;

and a lug is arranged in the sunken groove, one end of the lug is arranged in the sunken groove, and the other end of the lug extends out of the current collector.

In a third aspect, a lithium ion battery is provided. The lithium ion battery comprises the electrode pole piece.

In the embodiment of the application, a preparation method of an electrode plate is provided. The method comprises the steps that an isolation film and an active substance film layer are arranged in a tab preset area, and the isolation film and the active substance film layer arranged in the tab preset area are removed by laser, so that a bonding agent in the active substance film layer is prevented from remaining on a current collector; meanwhile, the situation that an active substance film layer arranged outside a preset region of the lug is jointly removed is avoided in the removing process, so that the area of the bottom of the concave groove is more adaptive to the area required by the connection of the lug.

Drawings

Fig. 1 is a schematic structural diagram illustrating a current collector provided with an isolation film according to the present application.

Fig. 2 is a schematic structural diagram illustrating an active material film layer disposed on a current collector according to the present application.

Fig. 3 is a schematic structural diagram illustrating the formation of a concave groove on a current collector according to the present application.

Fig. 4 is a schematic structural diagram of an electrode sheet according to the present application.

Fig. 5 is a flow chart of a method for manufacturing an electrode sheet according to the present application.

Description of reference numerals:

101-current collector, 102-isolating film, 103-active material film layer, 104-depressed slot, 105-tab and 001-electrode pole piece.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of 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 terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that embodiments of the application may be practiced in sequences other than those illustrated or described herein, and that the terms "first," "second," and the like are generally used herein in a generic sense and do not limit the number of terms, e.g., the first term can be one or more than one. 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.

The electronic device provided by the embodiment of the present application is described in detail by specific embodiments with reference to the accompanying drawings.

The embodiment of the application provides a preparation method of an electrode plate. Referring to fig. 1-5, the method includes the steps of:

s101, providing a current collector 101, wherein the current collector 101 is provided with a lug preset area, and the lug preset area is coated with an isolating film 102;

specifically, the current collector 101 includes a positive electrode current collector and a negative electrode current collector, wherein the positive electrode current collector is configured as an aluminum foil, and the negative electrode current collector is configured as a copper foil.

Coating an isolating film 102 on a preset tab area in an extrusion coating mode, wherein the isolating film 102 completely occupies the preset tab area;

in the prior art, a thermal expansion foaming pressure sensitive adhesive tape is arranged in a tab preset area, wherein the thermal expansion foaming pressure sensitive adhesive tape is adhered to the tab preset area in a bonding mode, and the adhesive tolerance is large, so that the thermal expansion foaming pressure sensitive adhesive tape cannot be completely matched with the set tab preset area.

The present example applies the isolating film 102 on the tab presetting area in a coating manner, so that the isolating film 102 can be matched with the tab presetting area. For example, the separator 102 having a width of 10mm, a length of 10mm and a thickness of 1 μm may be coated on the predetermined tab region by extrusion coating.

S102, coating active material slurry on the current collector 101 and the isolating film 102 to form an active material film layer 103;

specifically, the positive electrode active material slurry and the negative electrode active material slurry are coated on the positive electrode current collector and the negative electrode current collector, respectively, in a normal extrusion coating manner, and the active material slurry is also coated in the region where the separator 102 is located in the process.

The positive electrode active material slurry may be formed in the following manner: taking the positive active substance, the binder, the conductive agent and the solvent according to the proportion, mixing the binder and the solvent uniformly to prepare a glue solution, mixing the positive active substance and the conductive agent uniformly to obtain a dry mixture, adding the mixture into the glue solution, and fully stirring to obtain the positive active substance slurry.

The anode active material slurry may be formed in a manner such that: taking the negative active material, the binder, the conductive agent and the solvent according to the proportion, mixing the binder and the solvent uniformly to prepare a glue solution, mixing the negative active material and the conductive agent uniformly to obtain a dry mixture, adding the mixture into the glue solution, and fully stirring to obtain the negative active material slurry.

Specifically, the coated current collector is placed in an oven and dried at a temperature of 90 ℃ to 130 ℃, and the active material slurry forms an active material film layer to cover the current collector.

In the example, the isolating film 102 and the active material film layer 103 are coated in the preset tab area, and the active material film layer 103 is not directly contacted with the isolating film 102 in the preset tab area; in the removing process of step S103, the adhesive in the positive active material film layer and the negative active material film layer can be prevented from remaining on the current collector, and the current collector is prevented from yellowing and the like to affect the performance of the current collector.

Alternatively, referring to fig. 2, in step S102, the area of the active material film layer 103 is at least 10 times the area of the isolation film 102.

Specifically, the active material film layer 103 completely covers the current collector 101 to the maximum extent, so that the utilization rate of the current collector area is greatly improved, the coating amount of the active material is increased, and the purpose of improving the energy density of the lithium ion battery is achieved.

S103, removing the active material film layer 103 and the isolation film 102 arranged in the preset region of the tab by using laser to form a concave groove 104;

specifically, in step S103, when the active material film layer 103 disposed in the tab preset region is removed by using laser, the isolation film 102 isolates the active material film layer 103 from the current collector 101. For example, when the current collector 101 is an aluminum foil, the separator is coated on the current collector in advance, so that the binder in the positive electrode active material is prevented from remaining on the aluminum foil during laser cleaning, and the aluminum foil in the region of the concave groove 104 is prevented from yellowing.

In the prior art, the coated current collector enters an oven and is dried at the temperature of 80-150 ℃; in the process, the thermal expansion foaming peelable acrylic ester pressure-sensitive adhesive tape realizes thermal foaming, the bonding of the pressure-sensitive adhesive tape to a copper foil or an aluminum foil is failed after the high-temperature thermal expansion foaming (namely the peeling strength is basically 0N/m), and the pressure-sensitive adhesive tape and an active substance coated on the upper layer thereof automatically separate from a current collector; therefore, in the prior art, the separation of the active material in the preset area of the tab is carried out under the action of the pressure sensitive adhesive tape, and the mode is easy to cause that the separation of the active material in the preset area of the tab is not clean or the separation of the active material outside the preset area of the tab is carried out, so that the performance of the current collector is influenced.

Compared with the prior art, the active material film layer 103 and the isolation film 102 arranged in the preset region of the lug are removed by laser in the embodiment, so that the phenomenon that the active material film layer 103 arranged outside the preset region of the lug is removed together is avoided.

And S104, arranging a tab 105 in the concave groove 104 to form the electrode pole piece 001.

Specifically, because the active material film layer 103 and the isolation film 102 are removed to form the concave groove 104 in the preset region of the tab, the formation of the concave groove 104 exposes a part of the preset region of the tab to the current collector, and the tab 105 is welded on the exposed current collector to obtain the electrode piece meeting the requirements.

Optionally, the other side of the current collector is processed in the same manner, so that another concave groove opposite to the concave groove is formed on the other side of the current collector, and the tab 105 is arranged in the other concave groove.

Optionally, the preparation method of the electrode sheet 001 further includes: the current collector 101 formed with the concave groove 104 is rolled and stripped.

Specifically, the rolling and the slitting of the current collector 101 formed with the concave groove 104 of the present example may be performed after step S104 or before step S104.

For example, before step S104 (i.e., after step S103), the current collector formed with the concave grooves 104 is rolled and stripped; after the rolling and splitting are finished, the tabs 105 are arranged in the concave grooves 104, and then the electrode pole piece meeting the requirements is obtained.

For example, after step S104, a tab 105 is first disposed in the recessed groove 105, and after the tab 105 is disposed, special equipment is used to roll and strip the tab; among these, it is noted that: when rolling and splitting are carried out in the embodiment, the arrangement position and the lug structure of the lug need to be paid attention to, so that the lug structure is prevented from being damaged, and the performance of the electrode pole piece is prevented from being influenced.

Optionally, referring to fig. 3, the area of the tab presetting area is larger than the area of the bottom of the recess 104; the area of the bottom of the concave groove 104 matches the area required for the connection of the tab 105.

Specifically, the area of the preset region of the tab of the present embodiment is larger than the area of the bottom where the concave groove 104 is formed, so that the active material film layer and the isolation film arranged in the preset region of the tab can be conveniently removed by laser, and the active material film layer outside the preset region of the tab can be prevented from being removed.

The purpose of forming the depressed groove 104 in the tab predetermined region in this example is to weld the tab 105, and the bottom area of the depressed groove 104 and the area required for tab 105 connection are adapted to each other, for example, the bottom area of the depressed groove 104 is equal to the area required for tab connection or the bottom area of the depressed groove 104 is 1.25 times to 1.5 times the area required for tab connection.

Only the welding position of the tab on the sub-fluid is not covered by the active material film layer, so that the areas of the positive and negative current collectors are fully utilized, the increase of the thickness of the battery is reduced, and the lithium ion battery prepared by using the pole piece has higher volume energy density and lower internal resistance of the battery.

Alternatively, the thickness of the isolation film 102 is in the range of 0.5 μm to 5 μm, and the thickness of the active material film layer 103 is in the range of 40 μm to 80 μm.

The thickness range of the isolation film 102 in this example is 0.5 μm-5 μm, and under the condition that the thickness of the electrode plate is not affected, the isolation film 102 in the preset region of the tab plays a role in isolating the active material film layer from the current collector, so that the adhesive in the active material film layer is prevented from remaining on the current collector when the active material film layer is removed.

The active material film layer arranged in the preset area of the lug is convenient to remove by laser under the condition that the thickness of the electrode plate and the performance of the battery are not influenced.

Optionally, the material of the isolation film 102 includes graphite. The material of the isolation film 102 in this example is graphite, wherein graphite is a material in the active material slurry, and this example reduces the preparation cost of the electrode plate.

In a second aspect, referring to fig. 4, an embodiment of the present application provides an electrode tab 001. The electrode pad 001 includes: the current collector 101, the separator 102, and the active material film layer 103 are stacked; for example, the separator 102 is located between the current collector 101 and the active material film layer 103;

the current collector 101 forms the preset lug area, and part of the preset lug area is exposed out of the current collector 101;

the exposed current collector 101, the isolation film 102 and the active material film layer 103 define the concave groove 104;

for example, the depth of the concave groove 104 is equal to the sum of the thickness of the isolation film 102 and the thickness of the active material film layer 103; the separator 102 and the active material film layer 103 surround the side walls constituting the concave groove 104, and the exposed current collector 101 constitutes the bottom wall of the concave groove 104;

a tab 105 is arranged in the recessed groove 104, one end of the tab 105 is arranged in the recessed groove 104, and the other end of the tab 105 extends out of the current collector 101.

The electrode pole piece can reduce the current collector area occupied by a tab welding area to the maximum extent, greatly improve the utilization rate of the current collector area and increase the coating amount of active substances, thereby achieving the purpose of improving the energy density of the lithium ion battery; on the other hand, in the embodiment, the isolating film and the active substance film layer are arranged in the preset region of the tab, and the isolating film and the active substance film layer arranged in the preset region of the tab are removed by laser, so that the adhesive in the active substance film layer is prevented from remaining on the current collector; in addition, the situation that the active substance film layer arranged outside the preset area of the lug is jointly removed is avoided in the removing process.

In a third aspect, embodiments of the present application provide a lithium ion battery. The lithium ion battery comprises the electrode plate 001. The electrode pole piece is applied to the lithium ion battery, and the overall performance of the battery is improved.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. The term "comprising" is used to specify the presence of stated features, integers, steps, operations, elements, components, operations, components, or the components, and/components.

While the present embodiments have been described with reference to the accompanying drawings, it is to be understood that the invention is not limited to the precise embodiments described above, which are meant to be illustrative and not restrictive, and that various changes may be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The preparation method of the electrode plate is characterized by comprising the following steps:

s101, providing a current collector (101), wherein the current collector (101) is provided with a lug preset area, and an isolating film (102) is coated on the lug preset area;

s102, coating active material slurry on the current collector (101) and the isolating film (102) to form an active material film layer (103);

s103, removing the active substance film layer (103) and the isolation film (102) arranged in the preset region of the tab by adopting laser to form a concave groove (104);

and S104, arranging a tab (105) in the concave groove (104) to form an electrode pole piece (001).

2. The method for preparing the electrode pole piece according to claim 1, wherein the area of the tab presetting area is larger than the area of the bottom of the depressed slot (104); the area of the bottom of the concave groove (104) is matched with the area required by the connection of the tab (105).

3. The method for preparing the electrode plate according to claim 1, wherein the thickness of the isolation film (102) is in the range of 0.5 μm to 5 μm, and the thickness of the active material film layer (103) is in the range of 40 μm to 80 μm.

4. The method for preparing the electrode pole piece according to claim 1, wherein the material of the isolation film (102) comprises graphite.

5. The method for preparing the electrode plate according to claim 1, wherein in the step S103, when the active material film layer (103) disposed in the tab preset region is removed by using laser, the isolation film (102) isolates the active material film layer (103) from the current collector (101).

6. The method for preparing the electrode plate according to claim 1, further comprising the following steps: and rolling and splitting the current collector (101) formed with the concave groove (104).

7. The method for preparing the electrode plate according to claim 1, wherein in the step S102, the active material slurry is dried to form the active material film layer (103), wherein the drying temperature is in a range of 90 ℃ to 130 ℃.

8. The method for manufacturing an electrode sheet according to claim 1, wherein in step S102, the area of the active material film layer is at least 10 times the area of the separator film.

9. An electrode sheet prepared by the method for preparing an electrode sheet according to any one of claims 1 to 8, wherein the electrode sheet (001) comprises: the current collector (101), the isolation film (102) and the active material film layer (103) are arranged in a stacked manner;

the current collector (101) forms the preset tab area, the preset tab area is provided with the isolating film (102), and the active material film layer (103) is arranged on the current collector (102) and the isolating film (102); part of the lug preset area is exposed out of the current collector (101);

the exposed current collector (101) and the isolation film (102) and the active material film layer (103) define the concave groove (104);

be provided with utmost point ear (105) in depressed groove (104), utmost point ear (105) one end sets up in depressed groove (104), utmost point ear (105) other end extends current collector (101).

10. A lithium-ion battery, characterized in that it comprises an electrode sheet (001) according to claim 9.