CN-122000305-A - Self-supporting membrane for dry electrode and preparation method of dry electrode

CN122000305ACN 122000305 ACN122000305 ACN 122000305ACN-122000305-A

Abstract

The invention discloses a self-supporting membrane for a dry electrode and a preparation method of the dry electrode. In the preparation process of the self-supporting diaphragm for the dry electrode, the material mixing process of the self-supporting diaphragm is that non-medium mixing is firstly carried out and then medium mixing is carried out, wherein the non-medium mixing is that the materials are mixed under the action of low-strength shearing action generated by self-overturning, self-circulation and mutual friction among the materials which are caused by the integral movement of a mixing cavity in the mixing process, the materials of the dry electrode are placed in the mixing cavity, and the medium mixing is that functional structural members for stirring, shearing or collision are arranged in the mixing cavity. The invention initiates a step-type controllable mixing strategy for the first time, solves the root problem of uneven dispersion and fibrosis, abandons the traditional single and rough mixing mode, creatively and organically combines medium-free mixing and medium mixing, and completely eradicates performance fluctuation caused by uneven mixing from the source.

Inventors

MA YANWEI
SUN YU
SUN XIANZHONG
WANG DONGLIANG

Assignees

齐鲁中科电工先进电磁驱动技术研究院
中国科学院电工研究所

Dates

Publication Date: 20260508
Application Date: 20260126

Claims (10)

1. The preparation method of the self-supporting diaphragm for the dry electrode is characterized in that in the preparation process of the self-supporting diaphragm for the dry electrode, the material mixing process of the self-supporting diaphragm is that firstly non-medium mixing is carried out, and then medium mixing is carried out; The medium-free mixing is mixing by means of self-overturning and self-circulation of materials caused by integral movement of a mixing cavity and low-strength shearing action generated by mutual friction among the materials in the mixing process, wherein the materials of the dry electrode are placed in the mixing cavity; the medium mixing means that functional structural members for stirring, shearing or collision are arranged in the mixing cavity.
2. The method of claim 1, wherein the free-standing film is mixed with the medium after adding any material.
3. The method for preparing a self-supporting membrane for dry electrode according to claim 2, wherein the material of the self-supporting membrane comprises a conductive agent, a binder and an active material; The material mixing process of the self-supporting diaphragm comprises the following steps: (1) Mixing the conductive agent and the adhesive in a non-medium manner to obtain a mixture A; (2) Mixing the mixture A with a medium to obtain a mixture B; (3) Mixing the mixture B with the active substance in a non-medium manner to obtain a mixture C; (4) Mixture C was subjected to media mixing to give mixture D.
4. The method of claim 1, wherein the medium-free mixing is achieved by a mixing device having a closed mixing chamber, the interior of the mixing chamber is of a hollow structure, the interior of the mixing chamber is not provided with functional structural members for stirring, shearing or collision, and the medium-free mixing is achieved by rolling, tumbling, swinging, planetary revolution or a combination motion thereof of the mixing chamber.
5. The method for preparing a self-supporting membrane for dry electrode according to claim 4, wherein the mixing equipment used for the non-medium mixing is a non-ball mixer; The medium mixing is realized by a high-speed stirrer.
6. The method for preparing a self-supporting membrane for dry electrode according to claim 5, wherein the rotation speed of the ball-free mixer in the medium-free mixing is 200-600 rpm, and the time of the medium-free mixing is 10-30 minutes; the rotating speed of the high-speed stirrer is 400-600 rpm, and the mixing time of the medium is 10-30 minutes.
7. The method for preparing a self-supporting membrane for a dry electrode according to claim 1, wherein the non-medium mixing is a sectional mixing, and parameters of the non-medium mixing at different stages are not identical; The medium mixing is sectional mixing, and parameters of medium mixing in different stages are not completely the same.
8. The method for producing a self-supporting film for dry electrodes according to any one of claims 1 to 7, characterized in that the method for producing a dry electrode comprises the steps of: s1, mixing materials of the dry electrode; S2, carrying out high-shear force fiberizing treatment on the mixture obtained in the step S1, wherein the high-shear force fiberizing treatment is realized by jet milling; s3, performing film forming treatment on the fiberization mixture obtained in the step S2 to obtain a self-supporting film; and S4, compounding the self-supporting membrane obtained in the step S3 on a current collector to obtain the dry electrode.
9. The method according to claim 1, wherein the dry electrode material comprises a conductive agent, a binder and an active material, wherein the conductive agent is a conductive carbon black material, the binder is a fiberizable polymer binder, the active material is at least one of hard carbon, soft carbon, graphite, active carbon, lithium iron phosphate and a ternary material, and the mass ratio of the binder to the conductive agent is 2:1 to 1:3.
10. A method for preparing a dry electrode, characterized in that the dry electrode is obtained by compounding the self-supporting membrane obtained by the method for preparing a self-supporting membrane for a dry electrode according to any one of claims 1 to 9 onto a current collector.

Description

Self-supporting membrane for dry electrode and preparation method of dry electrode Technical Field The invention relates to the technical field of electrode materials, in particular to a self-supporting membrane for a dry electrode and a preparation method of the dry electrode. Background With the development of lithium ion batteries and related electrochemical energy storage devices toward high energy density and green manufacturing, the dry electrode preparation process is receiving attention because of no need of using organic solvents, low energy consumption and simplified flow. In dry electrode systems, the electrode material is generally composed of active substances, conductive agents and fiberizable polymeric binders, the uniformity of mixing of which has a decisive influence on the mechanical and electrochemical properties of the electrode. The dry electrode preparation process has no solvent, greatly reduced energy consumption and reduced pollution, and becomes an industry trend. Unlike wet systems, the dispersion of the components in dry systems is achieved entirely by mechanical mixing, especially the distribution of the binder in the mixing stage, directly affecting the subsequent conductive-adhesive network construction. However, the current dry electrode has uneven distribution of different components in the mixing cavity, the adhesive is easy to agglomerate, and finally the electrode has uneven internal structure and poor performance consistency. The problems are particularly prominent in the preparation process of thick electrodes or high-area-density electrodes, and become important factors for restricting the process stability and the large-scale application of dry electrodes. Therefore, a new method for preparing a dry electrode is needed to solve the problem of uneven material distribution in a dry system. Disclosure of Invention In order to solve the technical problems, the invention provides a self-supporting diaphragm for a dry electrode and a preparation method of the dry electrode, which ensure that all components (especially adhesive) are highly uniformly dispersed on a microscopic scale, and can stably prepare a full dry electrode with a high-strength thick film. In order to achieve the above purpose, the invention adopts the following technical scheme: in the preparation process of the self-supporting diaphragm for the dry electrode, the material mixing process of the self-supporting diaphragm is that firstly non-medium mixing is carried out and then medium mixing is carried out; The medium-free mixing is mixing by means of self-overturning and self-circulation of materials caused by integral movement of a mixing cavity and low-strength shearing action generated by mutual friction among the materials in the mixing process, wherein the materials of the dry electrode are placed in the mixing cavity; the medium mixing means that functional structural members for stirring, shearing or collision are arranged in the mixing cavity. Wherein, after any material is added, the mixture is mixed without medium, and then the mixture with medium is mixed. The materials in the step are conductive agents, the adhesives are materials, and the active substances are materials. For example, even if two active substances are used, they are counted as a class of materials. Wherein the material of the self-supporting membrane comprises a conductive agent, an adhesive and an active substance; The material mixing process of the self-supporting diaphragm comprises the following steps: (1) Mixing the conductive agent and the adhesive in a non-medium manner to obtain a mixture A; (2) Mixing the mixture A with a medium to obtain a mixture B; (3) Mixing the mixture B with the active substance in a non-medium manner to obtain a mixture C; (4) Mixture C was subjected to media mixing to give mixture D. The mixing device comprises a mixing cavity, a functional structural member mixing component, a rolling component, a turnover component, a swinging component, a planetary revolution component or a combination motion of the mixing cavity, wherein the mixing cavity is sealed, the mixing cavity is hollow, and the functional structural member mixing component for stirring, shearing or collision is not arranged in the mixing cavity. Wherein, the mixing equipment adopted by the non-medium mixing is a non-ball mixer; and/or the medium mixing is realized by adopting a high-speed stirrer. Preferably, the rotating speed of the ball-free mixer in the medium-free mixing is 200-600 rpm, and the time of the medium-free mixing is 10-30 minutes; the rotating speed of the high-speed stirrer is 400-600 rpm, and the mixing time of the medium is 10-30 minutes. Wherein, the medium-free mixing is sectional mixing, and parameters of medium-free mixing in different stages are not completely the same; The medium mixing is sectional mixing, and parameters of medium mixing in different stages are not completely the same. The preparation met