CN107768670A - Positive electrode material, preparation method and application, positive electrode preparation method - Google Patents

Abstract

The invention discloses a positive electrode material, a preparation method and application thereof, and a preparation method of a positive electrode, wherein the polyimide positive electrode material comprises the following components in percentage by mass: 5-40% of polyimide nano particles, 0-4% of auxiliary dispersant and 60-95% of water; the polyimide nanoparticles have the following structural formula:wherein, A1 and A2 are independently one of aryl, substituted aryl, heteroaryl and substituted heteroaryl. The water-based nano polyimide cathode material has the advantages of environmental protection and no pollution, and the nano size effect obviously improves the specific capacity and the charge-discharge rate performance of the polyimide cathode material, so that the water-based nano polyimide cathode material is more suitable for preparing a flexible energy storage battery with high energy density and high power density or a wearable energy storage battery.

Description

Positive electrode material, preparation method and application, positive electrode preparation method

technical field

The invention relates to the field of lithium-ion secondary batteries, in particular to a polyimide positive electrode material, its preparation method and application, and the preparation method of the polyimide positive electrode.

Background technique

Polyimide is one of the important engineering plastics, with a high temperature resistance of over 400°C, a long-term use temperature range of -200 to 300°C, no obvious melting point, high insulation performance, a dielectric constant of 4.0 at 103 Hz, and a dielectric loss of only 0.004 ～0.007, it belongs to F to H class insulating materials. According to the chemical structure of the repeating unit, polyimide can be divided into three types: aliphatic, semi-aromatic and aromatic polyimide. According to thermal properties, it can be divided into thermoplastic and thermosetting polyimides. Polyimide refers to a class of polymers containing imide rings (-CO-NH-CO-) on the main chain, among which polymers containing phthalimide structures are the most important. As a special engineering material, polyimide has been widely used in aviation, aerospace, microelectronics, nanometer, liquid crystal, separation membrane, laser and other fields. Because of its outstanding characteristics in performance and synthesis, whether it is used as a structural material or as a functional material, its huge application prospects have been fully recognized, and it is known as a "protion solver". It is believed that "without polyimide, there would be no microelectronics technology today".

Recent studies have shown that polyimide materials can be used as active materials for lithium-ion batteries or sodium-ion batteries, because the main chain of polyimide has pyromellitic anhydride, naphthalene tetracarboxylic anhydride and perylene tetracarboxylic anhydride. These groups can undergo reversible redox electrochemical reactions, such as imine groups can be oxidized to enol structures, accompanied by the carbonyl oxygen atoms bond or dissociate lithium ions or sodium ions. In theory, each tetraformic anhydride group can transfer 4 electrons, corresponding to a theoretical capacity of 300mAh/g, but the actual capacity in the experiment generally does not exceed 200mAh/g.

When polyimide is used as a positive electrode material for lithium-ion batteries or sodium-ion batteries, the actual specific capacity is far from its theoretical capacity, which is mainly limited due to the positive electrode preparation method used. The previously reported polyimide cathode materials are all in the form of bulk or film, and polyimide is insulating, and the internal active sites are all wrapped, resulting in a longer specific capacity activation cycle or overall ratio. low capacity. Moreover, the traditional preparation methods of polyimide cathode materials mostly use organic solvents to disperse. A large amount of organic solvents is likely to cause environmental pollution and endanger the health of production personnel, and the processing and recycling of large amounts of solvents will increase manufacturing costs.

Therefore, the prior art still needs to be improved and developed.

Contents of the invention

In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a polyimide positive electrode material and its preparation method and application, and a preparation method of the polyimide positive electrode, aiming at solving the problem that the existing preparation method uses an organic solvent to disperse, It is easy to cause environmental pollution, endanger the health of production personnel, and a large amount of solvent treatment and recycling will also increase the problem of manufacturing costs.

Technical scheme of the present invention is as follows:

A polyimide positive electrode material, wherein, by mass percentage, comprising: 5-40% polyimide nanoparticles, 0-4% auxiliary dispersant and 60-95% water;

The polyimide nanoparticles have the following structural formula:

Wherein, A1 and A2 are independently one of aryl, substituted aryl, heteroaryl and substituted heteroaryl.

Said polyimide cathode material, wherein said n is 50-10000.

The polyimide positive electrode material, wherein, the A1 has one of the following structural formulas:

The polyimide positive electrode material, wherein, the A2 has one of the following structural formulas:

The polyimide positive electrode material, wherein the polyimide nanoparticles have an average size range of 50-800 nanometers.

The polyimide cathode material, wherein the auxiliary dispersant is one or both of sodium carboxymethylcellulose, sodium alginate and sodium polyacrylate.

A kind of preparation method of polyimide positive electrode material as above, wherein, comprise step:

Firstly, ball mill the polyimide nanoparticles for 6-10 hours;

Then the ball-milled polyimide nanoparticles are taken out, mixed with an auxiliary dispersant and water, and then ground for 6-10 hours to prepare a polyimide positive electrode material.

A method for preparing a polyimide positive electrode as described above, comprising the steps of:

Mix the above-mentioned polyimide positive electrode material, conductive agent and water-based binder, and stir evenly;

Then it is coated on an aluminum foil, and finally the water is dried to prepare a polyimide positive electrode.

The method for preparing the polyimide positive electrode, wherein, by mass percentage (50%-70%): (20%-40%): (5%-15%), the polyimide positive electrode Mixing of materials, conductive agents and water-based binders;

And/or the water-based binder is one of sodium carboxymethylcellulose, sodium alginate, sodium polyacrylate, acrylate emulsion, polytetrafluoroethylene emulsion and polyvinylidene fluoride emulsion.

An application of the above-mentioned polyimide positive electrode material, wherein the polyimide positive electrode material is applied to a lithium ion secondary battery or a sodium ion secondary battery.

Beneficial effects: the invention provides a water-based dispersed polyimide positive electrode material, using the water-based nano-polyimide positive electrode material, in addition to the advantages of environmental protection and pollution-free, the nano-size effect significantly improves the polyimide positive electrode material. The specific capacity and charge-discharge rate performance of the material. Therefore, the water-based nano-polyimide positive electrode material provided by the present invention is particularly suitable for preparing flexible energy storage batteries or wearable energy storage batteries with high energy density and high power density.

Description of drawings

Fig. 1 is the scanning electron micrograph of the nanometer polyimide cathode material prepared in embodiment 1.

FIG. 2 is a graph showing the change in cycle capacity of a button battery assembled from the nano-polyimide positive electrode material in Example 5. FIG.

Detailed ways

The present invention provides a polyimide positive electrode material, its preparation method and application, and the preparation method of the polyimide positive electrode. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention will be further described in detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

A polyimide cathode material provided by the present invention, wherein, by mass percentage, comprises: 5-40% of polyimide nanoparticles, 0-4% of auxiliary dispersant and 60-95% of water;

The polyimide nanoparticles have the following structural formula:

Wherein, A1 and A2 are independently one of aryl, substituted aryl, heteroaryl and substituted heteroaryl.

Preferably, the A1 has one of the following structural formulas:

Preferably, the A2 has one of the following structural formulas:

In the present invention, the degree of polymerization n is 50-10000, the intrinsic viscosity is 1.0-3.0 dl/g, and the thermal decomposition temperature of the polyimide nanoparticles is above 420°C.

Preferably, the polyimide nanoparticles have an average size in the range of 50-800 nm.

Preferably, the auxiliary dispersant may be one or both of sodium carboxymethyl cellulose, sodium alginate and sodium polyacrylate.

The water-based dispersed polyimide positive electrode material provided by the invention has the advantages of environmental protection and pollution-free, and the nano size effect significantly improves the specific capacity and charge-discharge rate performance of the polyimide positive electrode material.

The present invention also provides a kind of preparation method of polyimide positive electrode material as above, wherein, comprise steps:

First, ball mill the polyimide nanoparticles for 6 to 10 hours (such as 8 hours);

Then the ball-milled polyimide nanoparticles are taken out, mixed with an auxiliary dispersant and water, and then ground for 6-10 hours (eg, 8 hours) to prepare a polyimide positive electrode material.

In the present invention, the polyimide cathode material can be prepared by adopting a two-stage process of first ball milling and then sand milling. The preparation process of the invention is simple, the preparation cost is low, and there is no pollution to the environment.

The present invention also provides a method for preparing a polyimide positive electrode using the above-mentioned polyimide positive electrode material, wherein, comprising steps:

Mix the above-mentioned polyimide positive electrode material, conductive agent and water-based binder, and stir evenly;

Then it is coated on an aluminum foil, and finally the water is dried to prepare a polyimide positive electrode.

Preferably, the polyimide positive electrode material, conductive agent and water-based binder are mixed according to the mass percentage of (50%-70%): (20%-40%): (5%-15%);

Preferably, the water-based binder may be one of sodium carboxymethylcellulose, sodium alginate, sodium polyacrylate, acrylate emulsion, polytetrafluoroethylene emulsion and polyvinylidene fluoride emulsion.

The present invention also provides an application of the above-mentioned polyimide positive electrode material, wherein the polyimide positive electrode material is applied to a lithium ion secondary battery or a sodium ion secondary battery. The invention uses the water-based nanometer polyimide positive electrode material, in addition to the advantages of environmental protection and pollution-free, the nano size effect significantly improves the specific capacity and charge-discharge rate performance of the polyimide positive electrode material. Therefore, the water-based nano-polyimide positive electrode material provided by the present invention is particularly suitable for preparing flexible energy storage batteries or wearable energy storage batteries with high energy density and high power density.

The charge-discharge performance of the polyimide positive electrode of the present invention in the lithium-ion secondary battery and the sodium-ion battery, the rate performance and the cycle performance etc. are charged and discharged by being assembled into a button battery (type 2032) by a conventional method in the art. test. The preparation and testing process is as follows:

First, mix the polyimide positive electrode material (referring to the effective content of solids in the aqueous positive electrode slurry) and conductive agent (such as acetylene black), and then add the aqueous binder solution (referring to the effective content of solids in the aqueous positive electrode slurry), Stir to form a uniform polyimide cathode slurry. The slurry is uniformly coated on an aluminum foil, then dried, rolled, and punched to prepare a circular polyimide positive electrode sheet. After drying in vacuum at a temperature of 120°C, place them in a glove box in a dry argon atmosphere, pair with metal lithium electrodes to form a lithium/polyimide button cell, and pair with a metal sodium electrode to form a sodium/polyimide battery. Amine button battery, the electrolyte is 1M LiPF ₆ /EC/DMC and 1M NaPF ₆ /EC/DMC respectively, the diaphragm is made of glass fiber diaphragm, the battery is charged and discharged by constant current method, the charging condition is: 0.3-1.1mA/cm ² ; The discharge current is 0.3-1.1mA/cm ² ; the cut-off voltage range is 1.50-3.50V (for Li/Li ⁺ ); or the cut-off voltage range is 1.50-3.50V (for Na/Na ⁺ ). It is tested by a computer-controlled LAND charge and discharge instrument. For the battery cycle performance test, the battery is charged and discharged at 0.5C to observe the change of the battery capacity with the number of charge and discharge times.

The present invention will be described in detail below by way of examples.

Example 1

Add 30 parts of polyimide resin raw materials (terephthalic anhydride-p-diamine diphenyl ether type) to the planetary ball mill for rough grinding for 8 hours, then add 0.6 gram of carboxymethylcellulose sodium and 269.4 gram of distilled water to mix into sand Continue grinding in the mill for 8 hours to obtain a water-based nano-polyimide positive electrode material with a solid content of 10.2%, and an average laser particle size of 480 nanometers. Stir and mix the water-based nano-polyimide positive electrode material, conductive carbon black and water-based acrylate binder LA133 in a mass ratio of 60:30:10 (referring to the mass percentage of the effective content of each component) and coat them on the aluminum foil. Then dry the moisture in a vacuum at 120 degrees to prepare a nanometer polyimide positive electrode sheet. FIG. 1 is a scanning electron micrograph of the nano-polyimide positive electrode material prepared in this example.

Example 2

Embodiment 2 is roughly the same as the steps of Embodiment 1. Add 20 parts of polyimide resin raw materials (terephthalic anhydride-p-phenylenediamine type) in a planetary ball mill for rough grinding for 8 hours, and then add 0.6 gram of carboxymethyl Sodium cellulose and 269.4 grams of distilled water were mixed into a sand mill and continued to grind for 8 hours to obtain a water-based nano-polyimide positive electrode material with a solid content of 7.1%, and an average laser particle size of 450 nanometers. Stir and mix the water-based nano-polyimide positive electrode material, conductive carbon black and polytetrafluoroethylene emulsion binder in a mass ratio of 60:30:10 (referring to the mass percentage of the effective content of each component) and coat it on the aluminum foil , and then vacuum-dry the water at 120 degrees to prepare a nano-polyimide positive electrode sheet.

Example 3

Embodiment 3 is substantially consistent with the steps of Embodiment 1. In a planetary ball mill, add 30 parts of polyimide resin raw materials (naphthalene dianhydride-p-phenylenediamine type) for rough grinding for 8 hours, then add 0.6 gram of sodium alginate and 269.4 grams of distilled water was mixed into a sand mill and continued to grind for 8 hours to obtain a water-based nano-polyimide positive electrode material with a solid content of 10.2%, and an average particle size of 470 nanometers by laser method. Stir and mix the water-based nano-polyimide positive electrode material, conductive carbon black and polyvinylidene fluoride emulsion binder in a mass ratio of 60:30:10 (referring to the mass percentage of the effective content of each component) and coat it on the aluminum foil , and then vacuum-dry the water at 120 degrees to prepare a nano-polyimide positive electrode sheet.

Example 4

Embodiment 4 is roughly consistent with the steps of Embodiment 1. Add 30 parts of polyimide resin raw materials (perylene dianhydride-p-diamine diphenyl ether type) to the planetary ball mill for rough grinding for 10 hours, and then add 0.6 gram of alginic acid Sodium and 269.4 grams of distilled water were mixed into a sand mill and continued to grind for 10 hours to obtain a water-based nano-polyimide positive electrode material with a solid content of 10.2%, and an average laser particle size of 410 nanometers. Stir and mix the water-based nano-polyimide positive electrode material, conductive carbon black and water-based acrylate binder LA133 in a mass ratio of 60:30:10 (referring to the mass percentage of the effective content of each component) and coat them on the aluminum foil. Then dry the moisture in a vacuum at 120 degrees to prepare a nanometer polyimide positive electrode sheet.

Example 5

The nano-polyimide positive electrode sheet in Example 1 was rolled and punched into a 12 mm circular positive electrode sheet, which contained 5.6 mg of active ingredient nano-polyimide. After vacuum drying at a temperature of 120 degrees, place it in a glove box with a dry argon atmosphere, and assemble it with a metal lithium electrode to form a lithium/polyimide button battery, and pair it with a metal sodium electrode to form a sodium/polyimide battery. Amine button battery, the electrolyte is 1MLiPF ₆ /EC/DMC and 1M NaPF ₆ /EC/DMC respectively, the diaphragm is made of glass fiber diaphragm, the battery is charged and discharged by constant current method, and the charging condition is: 0.3-1.1mA/cm ² ; The discharge current is 0.3-1.1mA/cm ² ; the cut-off voltage range is 1.50-3.50V (for Li/Li ⁺ ); or the cut-off voltage range is 1.50-3.50V (for Na/Na ⁺ ). It is tested by a computer-controlled LAND charge and discharge instrument. For the battery cycle performance test, the battery is charged and discharged at 0.5C to observe the change of battery capacity with the number of charge and discharge times. The test results are shown in Figure 2.

In summary, the present invention provides the polyimide positive electrode material, its preparation method and application, and the preparation method of the polyimide positive electrode. The invention provides a water-based dispersed polyimide positive electrode material. Using the water-based nano-polyimide positive electrode material, in addition to the advantages of environmental protection and pollution-free, the nano-size effect significantly improves the ratio of the polyimide positive electrode material. Capacity and charge-discharge rate performance. Therefore, the water-based nano-polyimide positive electrode material provided by the present invention is particularly suitable for preparing flexible energy storage batteries or wearable energy storage batteries with high energy density and high power density.

It should be understood that the application of the present invention is not limited to the above examples, and those skilled in the art can make improvements or transformations according to the above descriptions, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. A kind of 1. polyimides positive electrode, it is characterised in that by mass percentage, including：5-40% polyimides is received The water of rice corpuscles, 0-4% auxiliary dispersants and 60-95%；

   The polyimide nano particle has following structural formula：

   Wherein, A1 and A2 independently is one kind in aryl, substituted aryl, heteroaryl, substituted heteroaryl.
2. 2. polyimides positive electrode according to claim 1, it is characterised in that the n is 50-10000.
3. 3. polyimides positive electrode according to claim 1, it is characterised in that the A1 has in following structural formula It is a kind of：
4. 4. polyimides positive electrode according to claim 1, it is characterised in that the A2 has in following structural formula It is a kind of：
5. 5. polyimides positive electrode according to claim 1, it is characterised in that the polyimide nano particle is put down Equal size range is 50-800 nanometers.
6. 6. polyimides positive electrode according to claim 1, it is characterised in that the auxiliary dispersants are that carboxymethyl is fine Tie up one or both of plain sodium, sodium alginate and Sodium Polyacrylate.
7. A kind of 7. preparation method of the polyimides positive electrode described in any one of claim 1~6, it is characterised in that including Step：

   First by polyimide nano particle ball milling 6~10 hours；

   The polyimide nano particle after ball milling is then taken out, is mixed with auxiliary dispersants and water, is then ground 6~10 hours, Polyimides positive electrode is prepared.
8. 8. a kind of method that polyimides positive electrode using described in any one of claim 1~6 prepares polyimides positive pole, It is characterised in that it includes step：

   Any one of the claim 1~6 polyimides positive electrode, conductive agent and aqueous binders are mixed, and stirred equal It is even；

   Then it is coated on aluminium foil, finally dries moisture, polyimides positive pole is prepared.
9. 9. the method according to claim 8 for preparing polyimides positive pole, it is characterised in that by mass percentage for (50%-70%)：(20%-40%)：(5%-15%), by polyimides positive electrode, conductive agent and the aqueous binders Mixing；

   And/or the aqueous binder is sodium carboxymethylcellulose, sodium alginate, Sodium Polyacrylate, acrylic acid ester emulsion, poly- four One kind in PVF emulsion and polyvinylidene fluoride emulsion.
10. 10. the application of the polyimides positive electrode described in a kind of any one of claim 1~6, it is characterised in that will be described poly- Acid imide positive electrode is applied in lithium rechargeable battery or sodium ion secondary battery.