阅读说明：本技术 一种取代pvdf和nmp及导电剂的水性胶 (Aqueous adhesive for replacing PVDF (polyvinylidene fluoride), NMP (N-methyl pyrrolidone) and conductive agent ) 是由 曾涛 于 2021-09-08 设计创作，主要内容包括：本发明公开了一种取代PVDF和NMP及导电剂的水性胶,所述导电剂的水性胶按照以下质量分数配比：去离子水1000份、增稠剂羧甲基纤维素钠分散液85-115份、粘结剂聚丙烯酸酯和到聚氨酯分散液32-40份、导电剂多层石墨烯分散液5-8份、助剂乙醇1-2份和中和剂氨水1.5-3份,本发明一种取代PVDF和NMP及导电剂的水性胶,提高能量密度,提高导电材料的导电性,提高粘结剂的黏附力,同时还需要降低电池的内阻。传统碳纳米管浆料分散难度大,相容性差与粘结剂结合强度不佳；当碳纳米管长度较长时,影响锂离子的传递和扩散速度,本发明的目的降低电池成本,简化电池工艺,提高电池循环性能,增强电池工艺的环境友好性。(The invention discloses a water-based adhesive for replacing PVDF, NMP and a conductive agent, which is prepared from the following components in percentage by mass: 1000 parts of deionized water, 85-115 parts of thickener carboxymethylcellulose sodium dispersion liquid, 32-40 parts of binder polyacrylate and polyurethane dispersion liquid, 5-8 parts of conductive agent multi-layer graphene dispersion liquid, 1-2 parts of auxiliary agent ethanol and 1.5-3 parts of neutralizing agent ammonia water. The traditional carbon nanotube slurry has high dispersion difficulty, poor compatibility and poor bonding strength of a binder; when the length of the carbon nano tube is longer, the transfer and diffusion speed of lithium ions is influenced, and the invention aims to reduce the cost of the battery, simplify the battery process, improve the cycle performance of the battery and enhance the environmental friendliness of the battery process.)

1. The aqueous adhesive for replacing PVDF, NMP and a conductive agent is characterized by comprising the following components in percentage by mass:

2. the aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

3. the aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

4. the aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

5. the aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

。

6. the aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the adhesive polyacrylate and polyurethane dispersion liquid comprises one or more of polyacrylic acid (ester), polyimide, polyvinyl alcohol, polyurethane, polyester, polyether, polyacrylonitrile and other water-based adhesives.

7. The aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the thickener carboxymethyl cellulose sodium dispersion liquid comprises one or more of carboxymethyl cellulose sodium (CMC), propylene glycol sodium alginate, hydroxypropyl starch, polyvinylpyrrolidone (PVP), soybean glue, pectin, xanthan gum and other thickeners.

8. The aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the conductive agent multilayer graphene dispersion liquid comprises one or more conductive agents such as acetylene black, carbon nano tubes, graphene and conductive graphite.

9. The aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the auxiliary agent ethanol comprises one or more of ethanol, propanol, diethyl ether, N-methyl-pyrrolidone (NMP) and the like.

10. The aqueous gel of claim 1 substituted for PVDF and NMP with a conductive agent, wherein: the neutralizer ammonia water comprises one or 2 of ammonia water and sodium hydroxide.

Technical Field

The invention relates to a water-based adhesive of a conductive agent, in particular to a water-based adhesive for replacing PVDF, NMP and the conductive agent, belonging to the technical field of water-based adhesives of conductive agents.

Background

The binder used by the anode of the lithium ion battery at present is mainly polyvinylidene fluoride PVDF, needs to be matched with methyl pyrrolidone NMP for use, is expensive, is harmful to human bodies and the environment, is poor in environmental friendliness, needs to be recycled, is high in battery cost, and has potential safety hazards. The main stream of the binder used for the battery cathode is an aqueous binder, mainly a styrene butadiene copolymer type binder, and the styrene butadiene copolymer has no dispersion and thickening performance, so the binder needs to be matched with cellulose CMC for use, the using amount is large, the pole piece is fragile, the binding force is poor, the internal resistance is large, the most important is that the binder has no conductivity, and an additional conductive agent needs to be added. The binder has poor binding power, so that the powder falls off under the charge and discharge conditions, the internal resistance of the battery is increased, the capacity exertion of an active material is influenced, and the energy density of the battery is reduced. The current pole piece slurry needs to be added with a binder, a conductive agent and an active material separately, the slurry preparation process is complex, the time is long, and the production efficiency of the battery cell is influenced.

Disclosure of Invention

The present invention is directed to an aqueous adhesive that replaces PVDF, NMP, and a conductive agent, in order to solve the problems mentioned in the background art.

In order to achieve the purpose, the invention provides the following technical scheme: the aqueous adhesive for replacing PVDF, NMP and a conductive agent is prepared from the following components in percentage by mass:

as a preferable technical scheme of the invention, the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

as a preferable technical scheme of the invention, the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

as a preferable technical scheme of the invention, the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

as a preferable technical scheme of the invention, the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

as a preferable technical scheme of the invention, the adhesive polyacrylate and polyurethane dispersion liquid comprises one or more of polyacrylic acid (ester), polyimide, polyvinyl alcohol, polyurethane, polyester, polyether, polyacrylonitrile and other water-based adhesives.

As a preferable technical scheme of the invention, the thickener carboxymethyl cellulose sodium dispersion liquid comprises one or more of thickening agents such as carboxymethyl cellulose sodium (CMC), propylene glycol sodium alginate, hydroxypropyl starch, polyvinylpyrrolidone (PVP), soy gum, pectin, xanthan gum and the like.

As a preferred technical scheme of the invention, the conductive agent multilayer graphene dispersion liquid comprises one or more of acetylene black, carbon nanotubes, graphene, conductive graphite and other conductive agents.

As a preferable technical scheme of the invention, the auxiliary agent ethanol comprises one or more of ethanol, propanol, diethyl ether, N-methyl-pyrrolidone (NMP) and other auxiliary agents.

As a preferable technical scheme of the invention, the neutralizer ammonia water comprises one or 2 of ammonia water and sodium hydroxide.

Compared with the prior art, the invention has the beneficial effects that: the invention relates to a water-based adhesive for replacing PVDF, NMP and a conductive agent, which is provided with deionized water, a thickener sodium carboxymethyl cellulose dispersion liquid, a binder polyacrylate, a polyurethane dispersion liquid, a conductive agent multilayer graphene dispersion liquid, an auxiliary agent ethanol and a neutralizing agent ammonia water, so that the energy density is improved, the conductivity of a conductive material is improved, the adhesion of the binder is improved, and the internal resistance of a battery is required to be reduced. The traditional carbon nanotube slurry has high dispersion difficulty, poor compatibility and poor bonding strength of a binder; when the length of the carbon nano tube is longer, the transfer and diffusion speed of lithium ions is influenced, and the invention aims to reduce the cost of the battery, simplify the battery process, improve the cycle performance of the battery and enhance the environmental friendliness of the battery process.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a water-based adhesive for replacing PVDF, NMP and a conductive agent, which comprises the following components in parts by weight:

the first embodiment is as follows: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

example two: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

example three: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

example four: the aqueous adhesive of the conductive agent is prepared from the following components in percentage by mass:

wherein, the adhesive polyacrylate and polyurethane dispersion liquid comprises one or more of aqueous adhesives such as polyacrylic acid (ester), polyimide, polyvinyl alcohol, polyurethane, polyester, polyether, polyacrylonitrile, etc.

Preferably, the thickener carboxymethyl cellulose sodium dispersion comprises one or more of carboxymethyl cellulose sodium (CMC), propylene glycol sodium alginate, hydroxypropyl starch, polyvinylpyrrolidone (PVP), soybean gum, pectin, xanthan gum and other thickeners.

Further, the conductive agent multilayer graphene dispersion liquid comprises one or more of acetylene black, carbon nanotubes, graphene, conductive graphite and other conductive agents.

Furthermore, the auxiliary agent ethanol comprises one or more of ethanol, propanol, diethyl ether, N-methyl-pyrrolidone (NMP) and the like.

Wherein the neutralizer ammonia comprises one or 2 of ammonia and sodium hydroxide.

The technical scheme of the water-based adhesive is as follows:

binder polyacrylate and to polyurethane dispersion: dissolving a certain mass of adhesive in deionized water, fully and uniformly stirring in a reaction kettle to prepare adhesive dispersion liquid with the mass fraction of 20-50%, and standing for 6-12h in vacuum for later use.

Thickener carboxymethylcellulose sodium dispersion: respectively dissolving a certain mass of thickening agent in deionized water, fully and uniformly stirring in a reaction kettle to prepare thickening agent dispersion liquid with the mass fraction of 30-60%, and standing for 6-12h in vacuum for later use.

Conductive agent multilayer graphene dispersion liquid: adding a certain mass of thickening agent into deionized water, completely dissolving, adding a certain mass of conductive agent, and performing high-speed ball milling and dispersion for 0.5-4h by adopting a planetary ball mill to obtain a conductive agent dispersion liquid, wherein the content of the conductive agent is 2% -30%, and the content of the thickening agent is 1% -20%. And obtaining the conductive agent dispersion liquid for later use.

Water-based conductive adhesive: adding 1000 parts of deionized water (by mass, the same below), adding 80-150 parts of thickener dispersion, and stirring for 0.5-4 h. Then, 10-50 parts of adhesive dispersion liquid is added, the mixture is stirred for 0.5-4h, 1.5-30 parts of conductive agent dispersion liquid is added, the mixture is stirred for 0.5-4h, 0.5-5.5 parts of auxiliary agent and 0.1-3.5 parts of neutralizing agent are added continuously, and the mixture is stirred for 0.5-3h continuously. And obtaining the lithium ion battery aqueous conductive adhesive.

The performance test of the waterborne conductive adhesive comprises the following steps:

1. measurement of conductivity: the aqueous conductive adhesives of examples 1 to 4 were uniformly coated on the PE film to a thickness of 120 μm, respectively, vacuum-dried at 80 ℃ for 10 hours, and then cooled to room temperature, and the conductivity of each coating was measured using a four-probe tester. The results are shown in table 1:

	example 1	Example 2	Example 3	Example 4
					Conductivity s/cm	5.6	6.3	7.5	8.8

As can be seen from the results in Table 1, the conductive adhesive prepared by the invention has high conductivity which is 5.6-8.8 s/cm;

2. and (3) measuring the adhesive force: mixing the water-soluble conductive adhesive prepared in the embodiments 1-4 of the invention according to the mass fraction of 2.5% and the lithium manganate, ternary material, lithium cobaltate or lithium iron phosphate as the lithium ion battery anode material according to the mass fraction of 97.5%, adding deionized water according to the proportion of 40-70% of the total solid components, dispersing the anode slurry by using a double planetary kneader, testing by using a scraper finemeter in the dispersing process, and considering that the next step can be carried out when the fineness value reaches within 20 micrometers, namely preparing the anode electrode plate slurry prepared by using the water-soluble conductive adhesive;

the prepared positive electrode plate slurry is coated on a 14-micron thick aluminum foil serving as a current collector after passing through a 120-mesh screen, dried at the temperature of 110 ℃ for 5min, naturally cooled to room temperature along with the inside of a furnace, and rolled with the unit length load of 1.5 multiplied by 105N/m to obtain an electrode plate which is used as the positive electrode of the lithium ion battery. And rolling the prepared positive pole piece to prepare a strip shape with the size of 30cm multiplied by 3cm, adhering the current collector to a steel plate with the thickness of 1mm by using a double-sided adhesive tape, adhering a transparent adhesive tape on the coating layer, peeling the coating layer in a 180-degree direction at the speed of 90mm/min by using a tensile testing machine, testing for three times, and averaging to obtain the measured adhesion. The results are shown in Table 2

As can be seen from the data results in Table 2, the positive plate of the aqueous conductive adhesive prepared by the preparation method of the invention has high peel strength, i.e. strong adhesive force, and the maximum value reaches 8.5N/m.

3. Evaluation of simulated lithium battery performance

Lithium manganate, lithium cobaltate, a ternary material and lithium iron phosphate are respectively used as positive electrode materials, the aqueous conductive adhesive of the above examples 1-4 is used as a binder and a conductive agent to prepare a negative electrode of the lithium ion battery, and a commercial artificial graphite negative electrode is used to prepare a simulated lithium ion battery. The internal resistance of the battery and the gram capacity exertion of the positive electrode under the condition of voltage of 3.5V are tested under the condition of voltage of 3.7V.

The first coulombic efficiency of the charge-discharge cycle and the capacity retention rate after 200 cycles of the charge-discharge cycle were measured by a constant current and constant voltage method, and the results are shown in tables 3, 4, 5 and 6:

TABLE 3 lithium manganate Battery Performance

TABLE 4 lithium cobalt oxide cell Performance

TABLE 5 ternary material Battery Performance

TABLE 6 lithium iron phosphate battery Performance

From the above results, it is clear that the aqueous conductive adhesive of the present invention has a low amount of use because of its high peel strength and good adhesion.

In a simulated full cell, the aqueous conductive adhesive disclosed by the invention has a good dispersion effect on a positive active material, has internal resistance of the cell, improves the capacity exertion of the active material, and improves the cycle performance of the cell. The invention replaces polyvinylidene fluoride binder and N-methyl-pyrrolidone organic solvent for the anode of the lithium ion battery, reduces the cost of the battery, and has better environmental friendliness and good safety of the battery. By adopting the aqueous conductive adhesive, only active materials need to be added in the battery pulping process, the pulping process is simplified, and the pulping time is saved.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.