CN115663123A

CN115663123A - Electrode plate, preparation method thereof and battery

Info

Publication number: CN115663123A
Application number: CN202211333641.XA
Authority: CN
Inventors: 方送生; 李艳斌; 黄子麟
Original assignee: Shenzhen Bak Power Battery Co Ltd
Current assignee: Shenzhen Bak Power Battery Co Ltd
Priority date: 2022-10-28
Filing date: 2022-10-28
Publication date: 2023-01-31

Abstract

The invention provides an electrode plate, a preparation method thereof and a battery. The preparation method of the electrode slice comprises the following steps: mixing and electrode slice forming, wherein the mixing step comprises the following steps: mixing the non-fiberized first mixture with the fiberized conductive agent by a non-destructive mixing process to obtain a second mixed material, the first mixed material comprising an active material, a binder, and a conductive agent. The electrode plate forming step comprises: and after the mixing step, hot-pressing the second mixed material, and then performing hot rolling and hot-pressing compounding to obtain the finished electrode plate. The electrode plate prepared by the preparation method can avoid the damage of an active material aggregation structure caused by high-speed stirring because the fiberization of the binder is not involved in the preparation process, and further can improve the overall performance of the battery.

Description

Electrode plate, preparation method thereof and battery

Technical Field

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

Background

Lithium ion batteries are widely used in the fields of 3C, energy storage, electric vehicles, and the like because of their numerous advantages. The processing technology of the pole piece of the lithium ion battery can be divided into a wet process and a dry process according to whether a solvent is used or not. The wet process is the most common sheet-making process for preparing the lithium ion battery pole piece at present, in order to ensure the fluidity of the battery slurry, the solvent content of the battery slurry is generally over 30 percent, and the process of coating and preparing the pole piece is also the process of heating and drying a large amount of solvent, so the solvent is volatilized in the process of preparing the wet electrode piece by the wet process, on one hand, the environmental pollution is caused, and on the other hand, the manufacturing cost of the battery is increased. The dry electrode pole piece is manufactured by adopting a dry process, no solvent is added in the process, the problems can be avoided, the dry process can prepare the electrode film only through the fiberization of a dry binder, and the dry electrode pole piece can be obtained by hot-pressing and compounding the electrode film and a current collector. However, high energy agitation is often involved in the fiberization of the binder, which often results in structural failure of the active material, particularly the polycrystalline agglomerate material, and affects the storage, high temperature, and cycling performance of the battery.

Disclosure of Invention

The method for preparing the electrode plate can improve the overall performance of the battery material because high-energy stirring of the binder and the active material is avoided.

According to a first aspect, an embodiment provides a method for preparing an electrode sheet, including the steps of:

mixing: mixing a non-fiberized first mixed material with a fiberized conductive agent by a non-destructive mixing method to obtain a second mixed material, wherein the first mixed material comprises an active material, a binder and a conductive agent;

and (3) electrode plate forming: and after the mixing step, hot-pressing the second mixed material, and then performing hot rolling and hot-pressing compounding to obtain the finished product of the electrode plate.

Further, in the mixing step, the non-destructive mixing method includes one of planetary stirring, three-dimensional mixing, or double-screw stirring.

Further, in the mixing step, the mass ratio of the active material, the binder and the conductive agent in the first mixed material is in the range of (92-98): (1-4): (1-4); when the first mixed material is mixed with the fiberized conductive agent, the mass ratio of the first mixed material to the fiberized electric motor ranges from (95-98): (2-5).

According to a second aspect, an embodiment provides an electrode sheet, which is prepared by the preparation method of the first aspect.

According to a third aspect, an embodiment provides a battery, wherein electrode sheets of the battery are prepared by the preparation method of the first aspect.

The electrode slice prepared by the preparation method of the invention can avoid the damage of the agglomeration structure of the active material caused by high-speed stirring because the fiberization of the binder is not involved in the preparation process, thereby improving the storage, high temperature and cycle performance of the battery.

Detailed Description

The present invention will be described in further detail with reference to the following embodiments. In the following description, numerous specific details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted in different instances or may be replaced by other materials, methods. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.

Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various orders in the specification are for clarity of description of certain embodiments only and are not meant to imply a required order unless otherwise stated where a certain order must be followed.

For further explanation of the present application, the following will describe in detail an electrode sheet, a method for manufacturing the same, and a battery provided in the present application with reference to examples, but it should be understood that these examples are implemented on the premise of the technical solutions of the present application, and that detailed embodiments and specific operation procedures are given only for further explanation of the features and advantages of the present application, not for limitation of the claims of the present application, and the scope of protection of the present application is not limited to the following examples.

In a first aspect of the present invention, there is provided a method for manufacturing an electrode sheet, including the steps of:

mixing: mixing a first non-fiberized mixed material with a fiberized conductive agent by a non-destructive mixing method to obtain a second mixed material, wherein the first mixed material comprises an active material, a binder and a conductive agent.

The non-fiberized active material, the binder and the conductive agent are mixed nondestructively and then mixed with the fiberized conductive agent, and the fiberized conductive agent is used as a supporting structure of the self-supporting film, so that the damage to the active material structure in the fiberization process of the binder is avoided.

In one embodiment, in the mixing step, the non-destructive mixing method comprises one of planetary stirring, three-dimensional mixing, or double helix stirring.

In this embodiment, in the mixing step, the mass ratio of the active material, the binder, and the conductive agent in the first mixed material is in the range of (92 to 98): (1-4): (1-4); when the first mixed material is mixed with the fiberized conductive agent, the mass ratio of the first mixed material to the fiberized conductive agent ranges from (95-98): (2-5).

In the mixing step, the conductive agent of the fiber and the conductive agent of the first mixed material are each independently selected from at least one of Carbon Nanotubes (CNTs), carbon fibers, or carbon black (SP). The active material includes a positive electrode active material or a negative electrode active material. The positive active material comprises at least one of lithium cobaltate, lithium nickel cobalt manganese oxide (NMC), lithium nickel cobalt aluminate, lithium manganate, lithium iron phosphate and lithium iron manganese phosphate; the negative active material includes at least one of graphite, silicon oxygen, or silicon carbon. The binder comprises at least one of polyvinylidene fluoride (PVDF), polyethylene oxide, or sodium carboxymethylcellulose.

In this embodiment, in the step of forming the electrode sheet, the second mixed material is obtained from the support film by hot pressing at a temperature of 150 to 250 ℃. The hot calendering comprises: the self-supporting film is hot-calendered. Obtaining the rolled film, wherein the temperature of hot rolling is 150-250 ℃. The hot-pressing compounding comprises the following steps: and (3) hot-pressing and compounding the rolled film and the foil to obtain the electrode slice, wherein the hot-pressing and compounding temperature of the rolled film and the foil is 150-250 ℃.

In a second aspect of the invention, an electrode sheet is provided, which is prepared by the preparation method of the first aspect.

In a third aspect of the invention, a battery is provided, and the electrode plate of the battery is prepared by the preparation method of the first aspect.

Example 1

The embodiment provides a preparation method of a positive electrode dry-method electrode, which comprises the following steps:

a premixing step: NMC (Ni: mn: co = 5) ternary material, PVDF and SP were mixed as 95:2.5:2.5, the mixture was mixed uniformly in a planetary mixer, and the mixing speed of the planetary mixer was 2600rpm, to obtain a first mixed material.

Mixing: mixing the first mixed material with CNT according to a ratio of 97:3 is added into a double-screw mixer to be uniformly mixed to prepare a second mixed material, and the rotating speed of the screw is 800rpm.

The preparation method of the self-supporting film comprises the following steps: and hot-pressing the second mixed material by a hot press to prepare the self-supporting film, wherein the hot-pressing temperature is 180 ℃, and the thickness of the prepared supporting film is 252-260 mu m.

A rolling step: and (3) performing hot rolling on the prepared self-supporting film to prepare a rolled film, wherein the temperature of the hot rolling is 180 ℃, and the thickness of the rolled film is 152-156 mu m.

Hot-pressing compounding: and (4) carrying out hot-pressing compounding on the rolled film and the aluminum foil through a hot press to obtain the electrode plate.

The electrode plate prepared by the embodiment can be applied to lithium ion batteries.

Example 2

The embodiment provides a preparation method of a negative electrode dry-method electrode, which comprises the following steps:

a premixing step: graphite, PVDF and SP were mixed as 96:2:2 to obtain a first mixed material, and adding the mixture into a planetary mixer to be uniformly mixed, wherein the stirring speed of the planetary mixer is 2600rpm.

Mixing: mixing the first mixed material with CNT according to a ratio of 96:4, and uniformly mixing the mixture in a three-dimensional mixer to prepare a second mixed material, wherein the rotating speed of a main shaft of the three-dimensional mixer is 12rpm.

The preparation method of the self-supporting film comprises the following steps: and hot-pressing the second mixed material by a hot press to prepare the self-supporting film, wherein the hot-pressing temperature is 200 ℃, and the thickness of the prepared supporting film is 245-250 mu m.

A rolling step: and (3) performing hot rolling on the prepared self-supporting film to prepare a rolled film, wherein the temperature of the hot rolling is 200 ℃, and the thickness of the rolled film is 148-152 mu m.

Hot-pressing and compounding: and (4) carrying out hot-pressing compounding on the rolled film and the aluminum foil through a hot press to obtain the electrode plate.

The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.

Claims

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

mixing: mixing a non-fiberized first mixed material with a fiberized conductive agent by a non-destructive mixing method to obtain the second mixed material, wherein the first mixed material comprises an active material, a binder and a conductive agent;

an electrode plate forming step: and after the mixing step, hot-pressing the second mixed material, and then performing hot rolling and hot-pressing compounding to obtain the finished electrode plate.

2. The method of claim 1, wherein in the mixing step, the non-destructive mixing method comprises one of planetary stirring, three-dimensional mixing, or twin screw stirring.

3. The production method as set forth in claim 1, wherein in the mixing step, the mass ratio of the active material, the binder and the conductive agent in the first mixed material is in the range of (92-98): (1-4): (1-4); when the first mixed material is mixed with the fiberized conductive agent, the mass ratio of the first mixed material to the fiberized conductive agent ranges from (95-98): (2-5).

4. The method according to claim 1, wherein in the mixing step, the fiberized conductive agent is selected from at least one of carbon nanotubes and carbon fibers; the first mixed material conductive agent is at least one selected from graphite, conductive carbon black and graphene.

The active material includes a positive electrode active material or a negative electrode active material; the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyethylene oxide, or sodium carboxymethylcellulose.

5. The production method according to claim 4, wherein the positive electrode active material includes at least one of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate;

the negative active material includes at least one of graphite, silicon oxygen, or silicon carbon.

6. The preparation method according to claim 1, wherein in the step of forming the electrode sheet, the second mixed material is obtained by hot pressing a free-standing film at a temperature of 150 to 250 ℃;

in the step of forming the electrode plate, the hot calendaring comprises: carrying out hot rolling on the self-supporting film to obtain a rolled film, wherein the temperature of the hot rolling is 150-250 ℃;

in the step of forming the electrode plate, the hot-press compounding comprises the following steps: and carrying out hot-pressing compounding on the rolled film and the foil to obtain the electrode plate, wherein the hot-pressing compounding temperature of the rolled film and the foil is 150-250 ℃.

7. An electrode sheet, characterized in that it is prepared by the preparation method according to any one of claims 1 to 6.

8. A battery, characterized in that the electrode sheet of the battery is prepared by the preparation method according to any one of claims 1 to 6.