CN115084445A - Negative electrode dry film forming preparation process and negative electrode dry film - Google Patents

Abstract

The invention discloses a negative electrode dry film-forming preparation process and a negative electrode dry film, wherein the negative electrode dry film-forming preparation process comprises the following steps: stirring and mixing raw materials, namely mixing and stirring PTFE, SP and graphite by using a stirrer to obtain a premix; fiberizing the premix, and performing fiberization treatment on the premix to obtain a fiberized mixture; baking the mixture, and baking the fiberized mixture to obtain a cotton candy mixture; forming a film from the mixture, namely repeatedly folding the marshmallow-like mixture and performing rolling treatment for multiple times to obtain a thicker film; thinning the membrane, namely thinning the thicker membrane to obtain a negative membrane in accordance with the thickness; the negative electrode dry-method diaphragm is prepared by adopting the negative electrode dry-method film-forming preparation process. The negative electrode dry film-forming preparation process and the negative electrode dry film have the advantages of simple process, less material waste and low labor and material cost, and can improve the production efficiency and the production benefit.

Description

A kind of negative electrode dry method film-forming preparation process and negative electrode dry method membrane

technical field

The invention relates to the field of lithium battery production, in particular to a preparation process for negative electrode dry method film formation and a negative electrode dry method diaphragm.

Background technique

In the traditional field of lithium battery production, a coating head is used to coat the liquid slurry on the current collector. After the coating is completed, an oven needs to be used to evaporate the water or NMP solvent with the active material. The water or NMP solvent is only It is used for the dissolution of active substances, which is harmful to battery performance. In dry electrode technology, the solvent necessary in the traditional coating process is removed, the active material is rolled into a film in solid form, and then compounded with the current collector. This method greatly reduces energy consumption and harmful substances NMP solvent, economical The performance and environmental protection are greatly improved.

However, the existing lithium battery dry process has the disadvantages of numerous process steps, large waste of materials, and long time consumption, which greatly increases labor and material costs, and affects the production efficiency and production efficiency of enterprises.

In view of this, the purpose of the present invention is to provide a new technical solution to solve the existing technical problems.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention provides a negative electrode dry film-forming preparation process and a negative electrode dry film sheet, which solve the problems of the prior art such as numerous process steps, serious material waste, high labor and material costs, and production efficiency. Technical defects such as low performance and impact on production efficiency.

The technical scheme adopted by the present invention to solve its technical problems is:

A negative electrode dry film-forming preparation process, comprising the following steps:

S1, the raw materials are stirred and mixed, and PTFE, SP, and graphite are mixed and stirred by a mixer to obtain a premix;

S2, the premix is fibrillated, and the premix obtained in step S1 is subjected to a fibrillation treatment to obtain a fibrillated mixture;

S3, the mixture is baked, and the fibrous mixture obtained in step S2 is subjected to baking treatment to obtain a marshmallow-like mixture;

S4, the mixture is formed into a film, and the marshmallow-like mixture obtained in step S3 is repeatedly folded, and the repeatedly folded mixture is subjected to multiple rolling treatments to obtain a thicker film;

S5 , the thinning process of the membrane sheet, the thicker membrane sheet obtained in step S4 is subjected to a thinning treatment by using a pressing roller mechanism, so as to obtain a negative electrode membrane sheet that meets the thickness.

As a further improvement of the above technical solution, in step S1, the sum of the mass fractions of the premix is 100%, wherein the mass fraction of PTFE is 1%-10%, the mass fraction of SP is 0.5%-5%, and the mass fraction of graphite is 0.5%-5%. The quality score is 95%-98%.

As a further improvement of the above technical solution, the mass fraction of the PTFE is 2.5%, the mass fraction of SP is 1%, and the mass fraction of graphite is 96.5%.

As a further improvement of the above technical solution, in step S1, a 10L mixer is used to stir PTFE, SP, and graphite. The time is 40min-50min, and the fiberized mixture is obtained after stirring.

As a further improvement of the above technical solution, in step S2, the premix obtained in step S1 is subjected to fiberizing treatment by using a jet mill, and the rotating speed of the classification wheel of the jet mill is 8000-10000 r/min.

As a further improvement of the above technical solution, in step S3, an oven is used to bake the fiberized mixture obtained in step S2. Marshmallow-like mixture.

As a further improvement of the above technical solution, in step S4, the marshmallow-like mixture obtained in step S3 is repeatedly folded by an open mill, and rolled to form, the roll temperature of the open mill is 240°C-260°C, Gradually adjust from 2mm to 0.7mm to get a thicker diaphragm.

As a further improvement of the above technical solution, in step S5, the thicker film obtained in step S4 is thinned by a roller mechanism, the roller temperature of the roller mechanism is 120°C-130°C, and the roller of the roller mechanism The slit is gradually adjusted from 0.7mm to 0.1mm, and finally a 100-micron negative electrode diaphragm is obtained.

As a further improvement of the above technical solution, the negative film finally obtained in step S5 can be bent at 180° and can be compounded on the copper foil. The surface density of the negative film is 176g/㎡, and the compaction density is 1.59g/ ^cm3 .

The present invention also provides a negative electrode dry-processed membrane, which is prepared by using the negative electrode dry-processed film-forming preparation process.

The beneficial effects of the present invention are as follows: the present invention provides a negative electrode dry-process film-forming preparation process and a negative-electrode dry-process film sheet, and the negative-electrode dry-process film-forming preparation process and the negative electrode dry-process film sheet are prepared by stirring and mixing raw materials and premixing them. Several steps such as fibrillation, mixture baking, mixture film formation, and diaphragm thinning treatment can realize the preparation of negative electrode dry diaphragm, which has the advantages of simple process, fewer process steps, and less material waste, which can be saved in practical application. Labor and material costs, improve production efficiency, and improve the production efficiency of enterprises.

In summary, the negative electrode dry film-forming preparation process and the negative electrode dry film solve the technical defects of the prior art, such as numerous process steps, serious material waste, high labor and material costs, low production efficiency, and impact on production efficiency. .

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the process flow diagram of the negative electrode dry film-forming preparation process in the present invention.

Detailed ways

The concept, specific structure and technical effects of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts are all within the scope of The scope of protection of the present invention. In addition, all the coupling/connection relationships involved in the patent do not mean that the components are directly connected, but refer to a better coupling structure by adding or reducing coupling accessories according to the specific implementation. Various technical features in the present invention can be combined interactively under the premise of not contradicting each other, referring to FIG. 1 .

A negative electrode dry film-forming preparation process, comprising the following steps:

S1, the raw materials are stirred and mixed, and PTFE, SP, and graphite are mixed and stirred by a mixer to obtain a premix;

In step S1, the sum of the mass fractions of the premix is 100%, wherein the mass fraction of PTFE is 1%-10%, the mass fraction of SP is 0.5%-5%, and the mass fraction of graphite is 95%-98% . Preferably, in this embodiment, the mass fraction of PTFE is 2.5%, the mass fraction of SP is 1%, and the mass fraction of graphite is 96.5%.

In addition, in step S1, a 10L mixer is used to stir PTFE, SP and graphite, the speed of the barrel of the mixer is 80r/min-100r/min, the speed of the stirring paddle is 800-1000r/min, and the stirring time is 40min-50min , and a fibrillated mixture was obtained after stirring. Preferably, the drum speed of the mixer is 88 r/min, the linear speed of the mixing drum is 96.7 m/min, the rotation speed of the stirring paddle is 1000 r/min, the linear speed of the end of the mixer is 450.6 m/min, and the stirring time is 40 min.

S2, the premix is fibrillated, and the premix obtained in step S1 is subjected to a fibrillation treatment to obtain a fibrillated mixture;

In step S2, the premix obtained in step S1 is subjected to fiberizing treatment by using a jet mill, and the rotating speed of the classification wheel of the jet mill is 8000-10000r/min. In this embodiment, the rotation speed of the jet mill is preferably 9000r/min, The line speed is 1413m/min.

S3, the mixture is baked, and the fibrous mixture obtained in step S2 is subjected to baking treatment to obtain a marshmallow-like mixture;

In step S3, an oven is used to bake the fibrillated mixture obtained in step S2. The oven baking temperature is 220°C-250°C, and the baking time is 20-60min, preferably 30min. After baking, a marshmallow-like shape is obtained. mixture. Preferably, in this embodiment, the oven baking temperature is set to 230°C.

S4, the mixture is formed into a film, and the marshmallow-like mixture obtained in step S3 is repeatedly folded, and the repeatedly folded mixture is subjected to multiple rolling treatments to obtain a thicker film;

In step S4, the marshmallow-like mixture obtained in step S3 is repeatedly folded by an open mill, and rolled for multiple times. mm to obtain a thicker film, preferably, in this embodiment, the roll temperature of the mill is set to 250°C,

S5 , the thinning process of the membrane sheet, the thicker membrane sheet obtained in step S4 is subjected to a thinning treatment by using a pressing roller mechanism, so as to obtain a negative electrode membrane sheet that meets the thickness.

In step S5, the thicker film obtained in step S4 is thinned by means of a pair of rollers, the roll temperature of the pair of rollers is 120°C-130°C, and the roll gap of the pair of rollers is gradually adjusted from 0.7 mm to 0.1 mm, and finally obtain a negative electrode diaphragm with a thickness of about 100 microns; the negative electrode diaphragm finally obtained in step S5 can be bent at 180°, and there will be no defects on the surface of the diaphragm after bending, and the diaphragm has good flexibility and can be compounded to copper foil. Above, the areal density of the negative film is 176 g/m2, and the compaction density is 1.59 g/cm ³ . Preferably, in this embodiment, the roller temperature of the roller pairing mechanism is set to 120°C.

Based on the above-mentioned preparation process of negative electrode dry method film formation, the present invention also provides a negative electrode dry method film sheet, and the negative electrode dry method film sheet is prepared by using the negative electrode dry method film formation preparation process.

The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the described embodiments, and those skilled in the art can also make various equivalent deformations or replacements on the premise that does not violate the spirit of the present invention , these equivalent modifications or substitutions are all included within the scope defined by the claims of the present application.

Claims (10)

1. A preparation process for forming a film on a negative electrode by a dry method is characterized by comprising the following steps:

s1, stirring and mixing the raw materials, and mixing and stirring the PTFE, the SP and the graphite by using a stirrer to obtain a premix;

s2, fiberizing the premix obtained in the step S1 to obtain a fiberized mixture;

s3, baking the mixture, and baking the fiberized mixture obtained in the step S2 to obtain a cotton candy mixture;

s4, forming a film from the mixture, repeatedly folding the marshmallow-like mixture obtained in the step S3, and performing rolling treatment on the repeatedly folded mixture for multiple times to obtain a thicker film;

and S5, thinning the membrane, namely thinning the thicker membrane obtained in the step S4 by adopting a press roller mechanism to obtain the negative electrode membrane with the thickness.

2. The negative electrode dry film-forming preparation process according to claim 1, characterized in that: in step S1, the sum of the mass fractions of the premixes is 100%, wherein the mass fraction of PTFE is 1% -10%, the mass fraction of SP is 0.5% -5%, and the mass fraction of graphite is 95% -98%.

3. The negative electrode dry film-forming preparation process according to claim 2, characterized in that: the mass fraction of PTFE is 2.5%, the mass fraction of SP is 1%, and the mass fraction of graphite is 96.5%.

4. The negative electrode dry film-forming preparation process according to claim 1, characterized in that: in step S1, stirring PTFE, SP and graphite by a 10L stirring machine, wherein the rotating speed of the stirring machine barrel is 80r/min-100r/min, the rotating speed of the stirring paddle is 800-.

5. The dry film-forming preparation process of the negative electrode according to claim 1, characterized in that: in step S2, the pre-mixture obtained in step S1 is fiberized by an air jet mill, and the rotation speed of a grading wheel of the air jet mill is 8000-10000 r/min.

6. The negative electrode dry film-forming preparation process according to claim 1, characterized in that: in step S3, the fiberized mixture obtained in step S2 is baked in an oven at 220-250 ℃ for 30min to obtain a marshmallow-like mixture.

7. The negative electrode dry film-forming preparation process according to claim 1, characterized in that: in step S4, repeatedly folding the marshmallow-like mixture obtained in step S3 by using an open mill, and rolling and forming, wherein the roll temperature of the open mill is 240-260 ℃, and the roll gap is gradually adjusted from 2mm to 0.7mm, so as to obtain a thick film.

8. The negative electrode dry film-forming preparation process according to claim 1, characterized in that: in step S5, the thicker film obtained in step S4 is thinned by a roll-to-roll mechanism, the roll temperature of the roll-to-roll mechanism is 120 ℃ to 130 ℃, the roll gap of the roll-to-roll mechanism is gradually adjusted from 0.7mm to 0.1mm, and finally the negative electrode film of 100 microns is obtained.

9. The dry film-forming preparation process of the negative electrode according to claim 8, characterized in that: the negative electrode film finally obtained in the step S5 can be bent at 180 degrees and can be compounded on copper foil, the surface density of the negative electrode film is 176 g/square meter, and the compaction density is 1.59g/cm ³ 。

10. A negative electrode dry method diaphragm is characterized in that: the negative electrode dry-method diaphragm is prepared by adopting the negative electrode dry-method film-forming preparation process of any one of claims 1 to 9.

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