阅读说明：本技术 一种柔性电池及其制备方法和用途 (Flexible battery and preparation method and application thereof ) 是由 徐洲 于 2020-12-02 设计创作，主要内容包括：本发明属于电池技术领域,公开了一种柔性电极及其制备方法和用途,所述柔性电极包括具有孔隙的柔性导电基膜及分散于所述柔性导电基膜内部的电极组分,所述电极组分包括活性材料和导电剂,所述柔性导电基膜包括导电塑料。本发明的柔性电极,其电极组分与导电塑料基膜紧密结合形成统一体,不仅使得电极具有固有的柔性,还能够抑制活性材料和导电剂的脱落,组装成锂离子电池时有利于提高电极的稳定性从而提高电池的电化学性能,有利于推动柔性锂离子电池的商业化应用。(The invention belongs to the technical field of batteries, and discloses a flexible electrode and a preparation method and application thereof. The electrode component of the flexible electrode is tightly combined with the conductive plastic base film to form a whole, so that the electrode has inherent flexibility, and can inhibit the falling of the active material and the conductive agent, and the stability of the electrode is improved when the flexible electrode is assembled into a lithium ion battery, so that the electrochemical performance of the battery is improved, and the commercial application of the flexible lithium ion battery is promoted.)

1. The flexible electrode is characterized by comprising a flexible conductive base film with pores and an electrode component dispersed inside the flexible conductive base film, wherein the electrode component comprises an active material and a conductive agent, and the material of the flexible conductive base film comprises conductive plastic.

2. The flexible electrode of claim 1, wherein the flexible electrode is a flexible positive electrode or a flexible negative electrode;

preferably, the thickness of the flexible electrode is 5 μm to 1000 μm.

3. The flexible electrode of claim 1 or 2, wherein the conductive plastic comprises at least one of polyaniline, poly-p-phenylene, polyacetylene, polyphenylacetylene, polypyrrole, and polythiophene;

preferably, the active material is a positive electrode active material or a negative electrode active material;

preferably, the positive active material includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium manganese phosphate, ternary nickel-cobalt-manganese material and ternary nickel-cobalt-aluminum material;

preferably, the negative active material comprises at least one of lithium titanate, natural graphite, artificial graphite, carbon fiber, soft carbon, hard carbon, mesocarbon microbeads, elemental silicon, silicon oxide and silicon-carbon composite;

preferably, the conductive agent includes at least one of conductive carbon black, acetylene black, ketjen black, Super P, Super S, carbon nanotube, graphene, porous carbon, and carbon fiber;

preferably, the electrode component further comprises a binder, and the binder comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, polyvinyl alcohol, styrene butadiene rubber and hydroxymethyl cellulose.

4. The flexible electrode according to any one of claims 1 to 3, wherein the flexible conductive base film of the flexible electrode has a three-dimensional pore structure inside, and the electrode component is partially filled and bonded in the three-dimensional pore structure;

preferably, the porosity of the flexible electrode is 10% -60%.

5. The flexible electrode of claim 3 or 4, wherein the weight percentage of the active material is 85-95% based on 100% of the total mass of the electrode composition;

preferably, the conductive agent accounts for 1-10% of the total mass of the electrode component by weight;

preferably, the weight percentage of the binder is 0% -15%, preferably 0% -10%, and more preferably 0% -5% of the total mass of the electrode component as 100%;

preferably, the mass ratio of the electrode component to the conductive plastic is 50:1 to 1:1, preferably 20:1 to 10: 1.

6. A method of manufacturing a flexible electrode according to any one of claims 1 to 5, comprising the steps of:

(1) dry-mixing electrode components, wherein the electrode components comprise an active material and a conductive agent to obtain a mixed dry material;

wherein the electrode composition comprises an active material and a conductive agent;

(2) adding the mixed dry material and the pore-forming agent in the step (1) into molten conductive plastic, and dispersing to obtain mixed slurry;

(3) and (3) forming a film by using the mixed slurry obtained in the step (2), and removing the pore-forming agent to obtain the flexible electrode.

7. The method of claim 6, further comprising the step of die cutting the film sheet;

preferably, the pore-forming agent comprises at least one of water, ethanol, n-butanol, PVP, solid hydrocarbons and liquid hydrocarbons;

preferably, the content of the pore-forming agent is 0.5-5% by taking the total mass of the pore-forming agent and the dry mixed material in the step (1) as 100%;

preferably, the electrode component of step (1) further comprises a binder;

preferably, the dry mixed material in the step (1) is granular, and the particle size of the granules is preferably 0.1mm-2 mm;

preferably, in the step (2), the mass ratio of the mixed dry material to the molten conductive plastic is 50:1-1:1, preferably 20:1-10: 1.

8. The method according to claim 6 or 7, wherein the film forming manner in step (3) comprises at least one of pressure extrusion, coating, roll-to-roll film forming, blade film forming, casting, 3D printing, spraying and deposition, preferably at least one of roll-to-roll film forming, blade film forming and casting, and further preferably roll-to-roll film forming;

preferably, the pore former is removed by at least one selected from extraction and heating, preferably extraction.

9. Method according to any of claims 6-8, characterized in that the method comprises the steps of:

(1) uniformly mixing an active material, a conductive agent and a binder, and preparing mixed dry material particles by high-speed dispersion, wherein the particle size of the particles is 0.1-2 mm;

(2) adding the particles prepared in the step (1) and a pore-forming agent into molten conductive plastic, and stirring to prepare mixed slurry;

(3) forming a film by using the mixed slurry prepared in the step (2) at the temperature of 60-150 ℃ to obtain a membrane, removing the pore-forming agent by using an extraction mode, and die-cutting to obtain a flexible electrode;

wherein the active material is a positive electrode active material or a negative electrode active material;

by taking the total mass of the pore-forming agent and the mixed dry material in the step (1) as 100%, 85% -95% of the active material, 1% -10% of the conductive agent, 0% -10% of the binder and 0-free, and 0.5% -5% of the pore-forming agent.

10. A battery comprising a flexible electrode according to any one of claims 1 to 5.

Technical Field

The invention belongs to the technical field of batteries, and relates to a flexible electrode and a preparation method and application thereof.

Background

The lithium ion battery is a secondary battery with the advantages of high energy density, high stability, environmental friendliness and the like, and has been widely applied to energy storage devices of various electronic devices and electric vehicles. The lithium ion battery generally comprises a positive plate, a diaphragm, a negative plate, electrolyte and the like. The diaphragm is used for separating the positive plate from the negative plate, so that the positive plate and the negative plate are insulated, and electrolyte can be soaked and kept; the positive plate comprises a current collector and a positive active electrode coating; the negative plate comprises a current collector and a negative active electrode coating; the current collectors in the positive and negative electrode plates are mainly used for collecting currents generated by active electrode materials on the positive and negative electrode plates of the lithium ion battery to form larger currents, so that the active electrode coating is generally required to be in full contact with the current collectors, and the internal resistance is enabled to be as small as possible. At present, most of the lithium ion batteries that have been commercialized use metal foil as a current collector, for example: the aluminum foil is used as a positive plate current collector, and the copper foil is used as a negative plate current collector.

In recent years, new electronic products are more and more popular with consumers, such as intelligent helmets, intelligent sports shoes, folding mobile phones, folding tablet computers and the like. With the development of wearable device technology, flexible electronic devices required by wearable devices and the like are gradually developed towards flexibility, and how to develop a lithium ion battery with ultrahigh flexibility has become one of research hotspots in the field of energy storage. CN102522595A discloses a flexible thin film lithium ion battery and a preparation method thereof, the flexible thin film lithium ion battery is composed of an anode layer, a diaphragm, a cathode layer and an outer packaging layer, the anode layer is composed of an aluminum foil with the thickness of 16-30 mu M and an anode material printed on one side of the aluminum foil by adopting the gravure printing technology, the cathode layer is composed of a copper foil with the thickness of 10-30 mu M and a cathode material printed on one side of the copper foil by adopting the gravure printing technology, the outer packaging layer is an aluminum-plastic composite film, the anode material of the battery comprises a dispersant Hypermer KD-1, and the cathode material of the battery comprises a conductive agent vapor phase growth carbon fiber. CN108598371A discloses a composite negative plate for a flexible solid lithium ion battery and a preparation method thereof, wherein negative electrode material, conductive agent, inorganic material powder, lithium salt, dispersant and binder are adopted to prepare negative electrode slurry, the negative electrode slurry is coated on copper foil with the thickness of 8-14 μm, and the dried electrode plate is rolled and punched to obtain the composite negative plate.

However, when the metal foils such as aluminum foil and copper foil are used as current collectors, the positive and negative electrode plates generally have poor flexibility, and are easily broken or deformed under external forces such as bending and pulling, so that the performance of the battery is affected. The wearable electronic product is limited in that the existing lithium battery cannot keep good electrical performance and sealing performance after being bent for many times, and the bent part required by the wearable electronic product cannot be filled with the battery, so that the problem of short endurance time is caused.

Disclosure of Invention

In view of the above problems in the prior art, the present invention is directed to a flexible electrode, a method for manufacturing the same, and a use of the same. The problems that an electrode material of an existing flexible battery is easy to fall off, poor in flexibility performance, low in surface density, easy to cause falling off when bent and the like are solved.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a flexible electrode comprising a flexible conductive base film having pores and an electrode component dispersed inside the flexible conductive base film, the electrode component comprising an active material and a conductive agent, the flexible conductive base film comprising a conductive plastic.

In the flexible electrode, the flexible conductive base film adopts conductive plastic and disperses electrode component particles, and the electrode component and the conductive plastic base film are tightly combined to form a whole body to obtain the flexible electrode with an integrated structure, so that the electrode has inherent flexibility and good mechanical strength, can inhibit the falling of active materials and conductive agents, and is favorable for improving the stability of the electrode when assembled into a lithium ion battery so as to improve the electrochemical performance of the battery and promote the commercial application of the flexible lithium ion battery.

In the invention, organic conductive plastics are adopted, on one hand, electrode components such as active materials are carried, and on the other hand, the organic conductive plastics are used as current collectors for conducting and transmitting current. The flexible conductive base film has pores, so that lithium ions can be smoothly extracted and inserted.

The flexible electrode of the invention does not need to use the traditional metal copper or aluminum current collector, thus improving the proportion of active materials and further greatly improving the energy density of the battery.

The flexible electrode in the invention can be a flexible positive electrode or a flexible negative electrode.

The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the technical objects and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.

Preferably, the thickness of the flexible electrode is 5 μm to 1000 μm.

Preferably, the conductive plastic includes, but is not limited to, at least one of polyaniline, polyparaphenylene, polyacetylene, polyphenylacetylene, polypyrrole, and polythiophene.

Preferably, the active material is a positive electrode active material or a negative electrode active material.

Preferably, the positive active material includes, but is not limited to, at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium manganese phosphate, ternary nickel cobalt manganese material and ternary nickel cobalt aluminum material;

preferably, the negative active material includes, but is not limited to, at least one of lithium titanate, natural graphite, artificial graphite, carbon fiber, soft carbon, hard carbon, mesocarbon microbeads, elemental silicon, silicon oxy compound, and silicon-carbon composite.

Preferably, the conductive agent includes at least one of conductive carbon black, acetylene black, ketjen black, Super P, Super S, carbon nanotube, graphene, porous carbon, and carbon fiber.

Preferably, the electrode component further comprises a binder, wherein the binder comprises but is not limited to at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, polyvinyl alcohol, styrene-butadiene rubber and hydroxymethyl cellulose.

As a preferable technical solution of the flexible electrode of the present invention, the flexible conductive base film of the flexible electrode has a three-dimensional pore structure inside, and the electrode component is partially filled and combined in the three-dimensional pore structure. It should be noted that the filling is partial filling, and the unfilled portion of the three-dimensional porous structure is provided with pores, which are beneficial to the extraction and insertion of lithium ions.

Preferably, the flexible electrode has a porosity of 10% -60%, such as 10%, 12%, 15%, 18%, 20%, 25%, 27%, 30%, 35%, 38%, 42%, 46%, 50%, 55%, or 60%, etc.

Preferably, the weight percentage of the active material is 85% -95%, such as 85%, 87%, 88%, 90%, 91%, 92%, 94%, or 95%, etc., based on 100% of the total mass of the electrode component.

Preferably, the weight percentage of the conductive agent is 1% -10%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 10%, or the like, based on 100% of the total mass of the electrode component.

Preferably, the binder is present in an amount of 0% to 15%, such as 0%, 1%, 3%, 5%, 7%, 8%, 10%, 12%, 13%, 14%, etc., preferably 0% to 10%, and more preferably 0% to 5% by weight, based on 100% by weight of the total electrode component. Wherein 0% by mass means that the electrode composition does not contain a binder.

Preferably, the mass ratio of the electrode component to the conductive plastic is 50:1 to 1:1, such as 50:1, 30:1, 20:1, 10:1, 3:1 or 1:1, etc., preferably 20:1 to 10: 1.

The shape of the flexible pole piece is not limited in the invention, and includes but is not limited to round, rectangular or other irregular shapes, and can be selectively prepared by those skilled in the art according to the needs.

In a second aspect, the present invention provides a method of making a flexible electrode according to the first aspect, the method comprising the steps of:

(1) dry-mixing electrode components, wherein the electrode components comprise an active material and a conductive agent to obtain a mixed dry material;

wherein the electrode composition comprises an active material and a conductive agent;

(2) adding the mixed dry material and the pore-forming agent in the step (1) into molten conductive plastic, and dispersing to obtain mixed slurry, wherein the mixed slurry has viscosity;

(3) and (3) forming a film by using the mixed slurry obtained in the step (2), and removing the pore-forming agent to obtain the flexible electrode.

The method of the invention comprises the steps of firstly carrying out dry mixing on electrode components to obtain a mixed dry material, then mixing the mixed dry material with the melted conductive plastic and the pore-forming agent, forming a film, forming a diaphragm into a whole, removing the pore-forming agent to obtain the flexible electrode with an integrated structure, forming micropores in the original space occupied by the pore-forming agent and/or forming pores (such as micropores) when removing (such as dissolving out or volatilizing) the pore-forming agent, thereby forming a good three-dimensional porous structure in the conductive plastic base film, enabling lithium ions to be smoothly extracted and embedded, being beneficial to complete infiltration and flowing of electrolyte, reducing the internal resistance of the battery, and further improving the electrochemical performance of the battery.

The flexible electrode does not use the traditional metal copper or aluminum current collector, and the active material ratio is improved. Moreover, the prepared flexible electrode has good flexibility and good mechanical property.

The flexible pole piece prepared by the method has the advantages of controllable shape and size of the pole piece, and compared with the conventional preparation method, the method can be promoted from the previous manual laboratory stage to the batch production stage, and is easy to realize commercial application.

The operation timing of melting the conductive plastic is not limited in the present invention, and may be, for example, parallel to the step one.

The specific operation sequence of adding the mixed dry material and the pore-forming agent in the step (1) into the molten conductive plastic is not limited in the invention, and for example, the pore-forming agent can be added into the molten conductive plastic and stirred at once, then the mixed dry material is added, and stirring is slightly carried out, so that the molten plastic covers the mixed dry material.

As a preferred embodiment of the method of the present invention, the method of the present invention may further include the step of die cutting the film sheet.

Preferably, the pore-forming agent of step (2) is related to the conductive plastic and the active material as follows: the pore-forming agent has certain affinity with the conductive plastic, can be uniformly distributed in the conductive plastic, and does not react with the active material. The reason for this is that the present invention requires the formation of micropores in the conductive plastic layer to allow the lithium ions to be removed and inserted, and if there is no pore, the ions come out of the active material but are blocked by the conductive plastic layer, so that the battery is not formed.

Preferably, the pore-forming agent comprises at least one of water, ethanol, n-butanol, PVP, solid hydrocarbons and liquid hydrocarbons. But are not limited to the above listed types and other materials that can be extracted from the flexible electrode or decomposed and/or volatilized by heat can also be used in the present invention.

Preferably, the pore-forming agent is contained in an amount of 0.5% to 5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, or the like, based on 100% by mass of the pore-forming agent and the dry mixed material in step (1).

In the invention, the pore-forming agent is used for pore-forming, and is volatilized in the subsequent treatment step, so that the active material is not influenced.

Preferably, a fine-wire macroporous metal mesh with good flexibility, such as a copper wire mesh, is adopted and embedded when the conductive plastic is fused into a film so as to form a conductive network, so that the conductivity of the pole piece is increased while the using amount of a conductive agent is reduced, and the flexibility of the pole piece is not substantially lost.

Preferably, the electrode component in step (1) further comprises a binder.

In the present invention, the binder is an optional component, and may or may not be added. When organic conductive plastics are used as a bearing body, the adhesive is not required to be added with components; and (3) the binder is added only in a small amount, and the main function is to form mixed dry material particles in the dry material mixing process in the step (1), so that the preparation process is convenient. Preferably, the dry mixture in step (1) is in the form of granules, and the granules preferably have a diameter of 0.1mm to 2mm, such as 0.1mm, 0.5mm, 1.2mm, 1.5mm, 2mm, etc. The granular materials are beneficial to reducing the specific surface area of the mixed dry materials, and further can reduce the consumption of the conductive plastics.

In the present invention, the dry-blending method in the step (1) is not limited, and may be, for example, stirring or high-speed dispersion.

Preferably, in the step (2), the mass ratio of the mixed dry material to the molten conductive plastic is 50:1-1:1, such as 50:1, 30:1, 10:1, 3:1 or 1:1, etc., preferably 20:1-10: 1. The ratio between the two is influenced by the specific surface area of the dry mixture and the strength of the conductive plastic.

The dispersion method in the step (2) is not limited in the present invention, and may be, for example, stirring or high-speed dispersion.

Preferably, the film-making manner in step (3) includes, but is not limited to, at least one of pressure extrusion, coating, roll-to-roll film forming, doctor blade film forming, casting, 3D printing, spraying and deposition, preferably at least one of roll-to-roll film forming, doctor blade film forming and casting, and further preferably roll-to-roll film forming.

Preferably, the pore former is removed by at least one selected from extraction and heating, preferably extraction.

The extraction method can be, for example, immersing the membrane obtained in step (3) in an extracting agent to extract the pore-forming agent from the membrane, and the pore-forming method is extraction pore-forming.

The heating may be performed, for example, by heating the sheet obtained in step (3) to decompose and/or volatilize the pore-forming agent, and the pore-forming may be performed by heating. The heating pore-forming can be carried out under the condition of vacuumizing, so that better effect is obtained.

It should be noted that, because of the temperature of the melting process, the pore-forming by heating is not as feasible as the pore-forming by extraction, and the manner of removing the pore-forming agent in the present invention is preferably extraction.

As a further preferred technical solution of the method of the present invention, the method comprises the steps of:

(1) uniformly mixing an active material, a conductive agent and a binder, and dispersing at a high speed to prepare a mixed dry material;

(2) adding the particles prepared in the step (1) and a pore-forming agent into molten conductive plastic, and stirring to prepare mixed slurry;

(3) using the mixed slurry prepared in the step (2) to form a membrane by a pair of rollers, wherein the temperature for forming the membrane by the pair of rollers is 60-150 ℃ (such as 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 135 ℃ or 150 ℃ and the like) to obtain a membrane, then removing the pore-forming agent by adopting an extraction mode, and performing die cutting to obtain a flexible electrode;

wherein the active material is a positive electrode active material or a negative electrode active material;

by taking the total mass of the pore-forming agent and the mixed dry material in the step (1) as 100%, 85% -95% of the active material, 1% -10% of the conductive agent, 0% -10% of the binder and 0-free, and 0.5% -5% of the pore-forming agent.

In a third aspect, the present invention provides a battery comprising a flexible electrode according to the first aspect.

Compared with the prior art, the invention has the following beneficial effects:

in the flexible electrode, the flexible conductive base film adopts conductive plastic and disperses electrode component particles, and the electrode component and the conductive plastic base film are tightly combined to form a whole body to obtain the flexible electrode with an integrated structure, so that the electrode has inherent flexibility and good mechanical strength, can inhibit the falling of active materials and conductive agents, and is favorable for improving the stability of the electrode when assembled into a lithium ion battery so as to improve the electrochemical performance of the battery and promote the commercial application of the flexible lithium ion battery. Moreover, the flexible electrode of the invention does not need to use the traditional metal copper or aluminum current collector, thus improving the proportion of active materials and further greatly improving the energy density of the battery.

According to the method, electrode components are dry-mixed to obtain a mixed dry material, the mixed dry material is mixed with molten conductive plastic after granulation, and a membrane is integrated into a whole through membrane forming, drying and rolling, so that the flexible electrode with an integrated structure is obtained.

The flexible pole piece prepared by the method has the advantages of controllable shape and size of the pole piece, and compared with the conventional preparation method, the method can be promoted from the previous manual laboratory stage to the batch production stage, and is easy to realize commercial application.

According to the preferred technical scheme, the pore-forming agent is added for pore formation, so that a good three-dimensional porous structure can be formed in the conductive plastic base film, lithium ions can be smoothly extracted and inserted, complete infiltration and flowing of electrolyte are facilitated, the internal resistance of the battery is reduced, and the electrochemical performance of the battery is improved.

Drawings

FIG. 1 is a side sectional view of a positive electrode sheet prepared in example 1;

fig. 2 is a top view of the positive electrode sheet prepared in example 1;

fig. 3 is a top cross-sectional view of the negative electrode sheet prepared in example 2;

wherein 11-positive plate, 111-pore, 112-particles prepared in the second step, 113-conductive plastic polyaniline, 21-negative plate, 211-pore-forming agent-prepared pore, 212-particles prepared in the second step, and 213-conductive plastic PE.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The embodiments described below with reference to the drawings are exemplary and intended to be illustrative of the present invention and should not be construed as limiting the scope of the present invention. The specific process parameters and the like of the following examples are also only one example of suitable ranges, and a person skilled in the art can select the process parameters and the like within the suitable ranges through the description of the invention, and the specific selection of the following examples is not limited.

Example 1

The embodiment provides a flexible electrode and a preparation method thereof, wherein the manufacturing method of the electrode comprises the following steps:

in this embodiment, the total mass of the lithium cobaltate, the conductive agent, the binder, and the pore-forming agent is 100%, and the contents of the substances are as follows: 93% of lithium cobaltate, 5% of conductive agent, 1.8% of binder and 0.2% of pore-forming agent.

Uniformly mixing a lithium cobaltate positive electrode material, a conductive agent acetylene black and a binder polyvinylidene fluoride, and stirring to prepare mixed dry material particles with the particle size of 1 mm;

adding the particles prepared in the step one and a pore-forming agent glycerol into molten polyaniline, wherein the mass ratio of the molten polyaniline to the particles is 1:10, and stirring to prepare mixed slurry;

step three, forming a membrane by using the mixed slurry prepared in the step two, wherein the temperature for forming the membrane by using the mixed slurry is 100 ℃, and immersing the membrane into the extractant water so as to remove the pore-forming agent;

and step four, die cutting the diaphragm prepared in the step three to finally obtain a rectangular flexible pole piece, in particular to a positive pole piece.

The cross-sectional side view and the top view of the positive electrode sheet manufactured in the fourth step of this embodiment are shown in fig. 1 and fig. 2, wherein 111 is a pore, 112 is the particles manufactured in the second step, and 113 is conductive plastic polyaniline.

The shape and size of the base film and the die-cutting pole piece can be adjusted according to actual needs.

The embodiment has strong operability and improves the working efficiency.

Example 2

The embodiment provides a flexible electrode and a preparation method thereof, wherein the manufacturing method of the electrode comprises the following steps:

in this embodiment, the total mass of the silicon-carbon composite, the conductive agent, the binder, and the pore-forming agent is 100%, and the contents of the components are as follows: 85% of silicon-carbon composite, 7% of conductive agent, 5% of binder and 3% of pore-forming agent. Uniformly mixing a silicon-carbon composite negative electrode material, a conductive agent Ketjen black and a binder hydroxymethyl cellulose, and stirring to prepare mixed dry material particles with the particle diameter of 0.8 mm;

step two, adding the particles prepared in the step one and a pore-forming agent ethylene glycol into molten PE, wherein the mass ratio of the molten PE to the particles is 1:10, and stirring to prepare mixed slurry;

step three, forming a membrane by using the mixed slurry prepared in the step two, wherein the temperature for forming the membrane by using the roll is 120 ℃, and immersing the membrane into the extractant water so as to remove the pore-forming agent;

and step four, die cutting the diaphragm prepared in the step three to finally obtain a circular flexible pole piece, in particular to a negative pole piece.

The cross-sectional side view of the negative electrode sheet manufactured in the fourth step of this embodiment is shown in fig. 3, wherein 211-pores formed by the pore-forming agent, 212-particles manufactured in the second step, 213-conductive plastic PE.

According to the embodiment, the shape and size of the die-cutting pole piece can be adjusted according to actual needs so as to meet the requirements of lamination or winding pole pieces required by different battery cell types.

The embodiment has strong operability and improves the working efficiency.

Example 3

The embodiment provides a flexible electrode and a preparation method thereof, wherein the manufacturing method of the electrode comprises the following steps:

in this example, the contents of each substance are as follows, taking the total mass of NCM811, the conductive agent, the binder and the pore-forming agent as 100%: NCM 81190%, conductive agent 5%, adhesive 3% and pore-forming agent 2%.

Uniformly mixing an NCM811 positive electrode material, a conductive agent Super P and a binder polytetrafluoroethylene, and preparing mixed dry material particles with the particle size of 0.5mm by mixing;

step two, adding the particles prepared in the step one and a pore-forming agent N-methyl pyrrolidone into molten PP, wherein the mass ratio of the molten PP to the particles is 1:15, and stirring to prepare mixed slurry;

step three, adopting a tape casting method to form a film on the mixed slurry prepared in the step two to form a diaphragm, and drying the diaphragm at 140 ℃ under a vacuum condition to remove the pore-forming agent;

and step four, die cutting the diaphragm prepared in the step three to finally obtain a rectangular flexible pole piece, in particular to a positive pole piece.

Example 4

The embodiment provides a flexible electrode and a preparation method thereof, wherein the manufacturing method of the electrode comprises the following steps:

in this embodiment, the total mass of the natural graphite, the conductive agent, the binder, and the pore-forming agent is 100%, and the contents of the respective substances are as follows: 94% of natural graphite, 1% of conductive agent, 4% of binder and 1% of pore-forming agent.

Uniformly mixing natural graphite, a conductive agent carbon nanotube and a binder polyacrylic acid, and stirring to prepare mixed dry material particles, wherein the particle size of the particles is 0.3 mm;

step two, adding the particles prepared in the step one and pore-forming agent water into molten PE, wherein the mass ratio of the molten PE to the particles is 3:1, and dispersing at high speed to prepare mixed slurry;

thirdly, forming a film by using the mixed slurry prepared in the second step through a scraper, forming a membrane, and drying at 100 ℃ under a vacuum condition to remove the pore-forming agent;

and step four, die cutting the diaphragm prepared in the step three to finally obtain a circular flexible pole piece, in particular to a negative pole piece.

Example 5

In this embodiment, the total mass of the lithium cobaltate, the conductive agent, the binder, and the pore-forming agent is 100%, and the contents of the substances are as follows: 96.5% of lithium cobaltate, 1.5% of conductive agent, 1.8% of binder and 0.2% of pore-forming agent.

Uniformly mixing a lithium cobaltate positive electrode material, a conductive agent acetylene black and a binder polyvinylidene fluoride, and stirring to prepare mixed dry material particles with the particle size of 1 mm;

adding the particles prepared in the step one and a pore-forming agent glycerol into molten polyaniline, wherein the mass ratio of the molten polyaniline to the particles is 1:10, and stirring to prepare mixed slurry;

step three, forming a film by using the mixed slurry prepared in the step two to form a roll, wherein the roll forming temperature is 100 ℃, a fine-wire macroporous metal mesh (specifically a copper wire mesh) is embedded during film forming to form a membrane, and the membrane is immersed in the extractant water so as to remove the pore-forming agent;

and step four, die cutting the diaphragm prepared in the step three to finally obtain a rectangular flexible pole piece, in particular to a positive pole piece.

Compared with embodiment 1, the embodiment not only reduces the using amount of the conductive agent and improves the content of the active substances, but also increases the conductivity of the pole piece, and improves the electrochemical performance of the material on the premise of basically not losing the flexibility of the pole piece.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.