CN104327762A - Enhanced-type composite adhesive of lithium ion battery, preparation method and application thereof - Google Patents

Abstract

The invention discloses a lithium-ion battery reinforced composite adhesive, a preparation method and an application, and belongs to the technical field of lithium-ion battery adhesives. In the present invention, the carboxyl group on the carboxyl-functionalized carbon nanotube can condense and bond with groups such as hydroxyl groups in the water-soluble polymer to form a reinforced composite adhesive. The composite adhesive has the following three advantages: first, the tensile strength of the adhesive is greatly enhanced; second, the three-dimensional conductive network formed by carbon nanotubes can effectively improve the conductivity of the composite adhesive; third, the composite adhesive The agent contains a specific functional group that can bond with the electrode active material and is conducive to ion transport. After a large volume change in the active material, it can still maintain a close combination with the active material, which can prevent the volume expansion caused by the charging and discharging process. De-powdering phenomenon, improve the cycle stability of electrode materials.

Description

A kind of lithium-ion battery enhanced composite binder, preparation method and application

technical field

The invention relates to a lithium-ion battery reinforced composite adhesive, a preparation method and application of the composite adhesive, and belongs to the technical field of lithium-ion battery adhesives.

Background technique

With the development of portable electronic devices and electric vehicles, the energy density of lithium-ion batteries is increasingly demanding. In order to achieve the purpose of increasing the energy density of lithium-ion batteries, key materials such as positive electrodes, negative electrodes, separators, and electrolytes need to be improved. In terms of negative electrodes, traditional graphite materials cannot meet the requirements of the new generation of lithium-ion batteries due to their low theoretical mass specific capacity (375mA h/g). New anode materials with high specific capacity have gradually attracted the attention of the majority of researchers, but such materials are often accompanied by large volume changes when lithium ions are intercalated and deintercalated, which may easily cause the active material to detach from the current collector and lead to battery capacity attenuation. At present, methods such as nanonization of electrode materials and compounding with inactive materials are often used to improve the charge-discharge performance of high-capacity negative electrodes. In addition, the new electrode binder can also effectively immobilize the active materials and improve the cycle stability of the new anode materials. Commonly used binders such as polyvinylidene fluoride (PVDF) N-methylpyrrolidone (NMP) solution, when used as a binder for materials with small volume changes, can better fix the active material on the current collector. However, when used as a binder for bulky materials, it is prone to plastic deformation, thereby separating it from the active material. For this reason, people have successively developed water-based adhesives such as starch (application number: 200380102888.X), multi-component copolymer (application number: 200910193676.6) and the like. However, currently commonly used water-based adhesives such as carboxymethyl cellulose are straight-chain molecules, which have limited cohesive force and tensile strength, and low ion and electronic conductivity. Chinese patent (application number: 200680029579.8) discloses a composite binder containing carbon nanotubes, which is composed of functionalized carbon nanotubes (such as introducing carboxyl functional groups into the ends or surfaces of carbon nanotubes) and light and/or After heat treatment, it is composed of polymerizable substances (such as polymerizable monomers, oligomers, etc.), polymers and their mixtures, in which carbon nanotubes can significantly improve the mechanical properties of the adhesive and firmly combine with the polymer. However, because the binding force between the binder and the active material is not considered, there is still room for improvement in its cycle stability. And the dissolution of the adhesive still requires the use of organic solvents, which will have a certain impact on the environment.

Contents of the invention

The object of the present invention is to provide a lithium-ion battery reinforced composite adhesive with strong binding force with active materials, high electrical conductivity and high tensile strength.

At the same time, the invention also provides a preparation method of a lithium-ion battery reinforced composite adhesive.

Finally, the present invention provides an application of the above-mentioned composite binder in a lithium battery.

In order to achieve the above object, the technical solution adopted in the present invention is:

A lithium-ion battery-enhanced composite binder, which is composed of carboxyl-functionalized carbon nanotubes and water-soluble polymers containing two groups, A and B, where the A group is a carboxyl group, and the B group is a hydroxyl and/or amino group , the mass ratio of the carbon nanotubes to the water-soluble polymer is 0.1-1.

The preparation of the carboxyl-functionalized carbon nanotubes can refer to the patent (application number: 200680029579.8). The acid treatment method is: adding the carbon nanotubes accounting for 1 to 2% of the solution mass into the mixed solution of concentrated sulfuric acid and concentrated nitric acid, and ultrasonically Reflux at 60-120°C for 2-12 hours (to truncate carbon nanotubes so that they are less prone to self-winding, and to graft hydrophilic functional groups such as carboxyl groups on the fractures to enhance their dispersion in aqueous solution), wash ,dry.

The volume ratio of concentrated sulfuric acid and concentrated nitric acid in the mixed solution is 3:(1～2).

The parameters of the ultrasound are: ultrasound frequency 20-30kHz, power 450-550W, ultrasound time 6-24 hours. Preferably, the ultrasonic frequency is 22kHz, and the power is 500W.

The water-soluble polymer is any one of sodium alginate, sodium carboxymethyl cellulose, carboxymethyl chitosan, carboxymethyl chitin, sodium carboxymethyl starch, or the cross-linked water formed by the above-mentioned several kinds. gel etc.

A method for preparing a lithium-ion battery-enhanced composite adhesive comprises the following steps: adding carboxyl-functionalized carbon nanotubes and water-soluble macromolecules into water and mixing them uniformly.

The application of a lithium ion battery enhanced composite binder in a lithium battery, wherein the composite binder is used as an essential component of the negative electrode, and its dosage is 20-50% of the mass of the negative electrode active material.

The negative electrode active material includes carbon, silicon, tin and composite materials thereof (such as silicon carbon, silicon-tin composite materials). Carbon active materials mainly include graphite (such as natural graphite, artificial graphite), non-graphite (such as mesocarbon microspheres, biomass carbon) and carbon nanomaterials. Silicon-based active materials include silicon monomers (crystalline and amorphous), nano-silicon (spherical or linear), silicon-carbon composites, silicon oxides (such as SiO _0.8 , SiO _1.1 ), silicon alloys (such as Li-Si, Mn -Si, Al-Si), etc. Tin-based active materials include tin-based oxides, tin-based alloys, tin-carbon composites (such as tin-cobalt-carbon composite amorphous materials), and the like.

In a lithium battery, the electrode material also contains a conductive agent in addition to the negative electrode active material and the composite binder, and the amount of the conductive agent is 10-50% of the mass of the negative electrode active material.

The conductive agent includes carbon nanotubes, superconducting carbon black, superconducting carbon, carbon fibers, Ketjen black, graphene, metal nanofibers (such as copper nanofibers, nickel nanofibers) and the like.

Beneficial effects of the present invention:

In the present invention, the carboxyl groups on the carboxyl functionalized carbon nanotubes can condense and form bonds with groups such as hydroxyl groups in the water-soluble macromolecules to form a reinforced composite adhesive. The composite adhesive has the following three advantages: first, the tensile strength of the adhesive is greatly enhanced; second, the three-dimensional conductive network formed by carbon nanotubes can effectively improve the conductivity of the composite adhesive; third, the adhesive There is a chemical bond between the active material and the electrode active material, and the close combination with the active material can still be maintained after the active material undergoes a large volume change. Compared with the composite binder disclosed in the patent (Application No.: 200680029579.8), the composite binder of the present invention contains groups such as carboxyl groups that can bond with electrode active materials and facilitate the transmission of lithium ions. The de-powdering phenomenon caused by volume expansion improves the cycle stability of electrode materials.

Description of drawings

Fig. 1 is the test graph of cycle performance of lithium battery in the embodiment 1 of the present invention;

Fig. 2 is the curve diagram of lithium battery cycle performance test in embodiment 2;

Fig. 3 is the test graph of cycle performance of lithium battery in embodiment 3;

Fig. 4 is a curve diagram of lithium battery cycle performance test in comparative example 1;

FIG. 5 is a test curve of the cycle performance of the lithium battery in Comparative Example 2.

Detailed ways

The following examples only illustrate the present invention in further detail, but do not constitute any limitation to the present invention.

Example 1

The lithium-ion battery-enhanced composite adhesive in this embodiment is composed of 0.01 g of carboxyl-functionalized carbon nanotubes and 0.1 g of sodium alginate.

The preparation method of carboxyl functionalized carbon nanotubes in this embodiment comprises the following steps:

(1) Prepare 120mL of mixed solution of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:1;

(2) Add 3g of carbon nanotubes to the mixture, ultrasonicate for 8 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 120°C for 2 hours, remove the supernatant after centrifuging the obtained solution, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery-enhanced composite adhesive in the present embodiment comprises the following steps:

(1) Add 0.1g sodium alginate to 16mL deionized water to obtain a uniform, transparent viscous solution;

(2) Add 0.01 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite binder solution.

The application of the enhanced composite binder in the lithium-ion battery in the present embodiment comprises the following steps:

(1) Add 0.3g nano-silica powder and 0.1g superconducting carbon black to the composite binder solution prepared above, magnetically stir and ultrasonically disperse to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, dry it in vacuum at 100°C for 6 hours, then punch it to make a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C and place it In a glove box filled with argon gas, a lithium sheet was used as the counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) was used as the electrolyte, and a celgard2400 separator was used as the separator to assemble the half-cell.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C. The first reversible capacity reaches more than 2200mA h/g, and it remains above 2000mA h/g after 50 cycles. The cycle efficiency is more than 90%. The efficiency is always above 97%. See Figure 1 for the cycle performance test curve.

Example 2

The lithium-ion battery-enhanced composite adhesive in this example is composed of 0.1 g of carboxy functionalized carbon nanotubes and 0.1 g of carboxymethyl chitosan.

The preparation method of carboxyl functionalized carbon nanotubes in this embodiment comprises the following steps:

(1) Prepare 120mL of mixed solution of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:2;

(2) Add 3g of carbon nanotubes to the mixture, ultrasonicate for 6 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 60°C for 12 hours, remove the supernatant after the obtained solution is centrifuged, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery-enhanced composite adhesive in the present embodiment comprises the following steps:

(1) 0.1g carboxymethyl chitosan was added to 8mL deionized water to obtain a uniform and transparent viscous solution;

(2) Add 0.1 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite adhesive solution.

The application of the enhanced composite binder in the lithium-ion battery in the present embodiment comprises the following steps:

(1) Add 0.2g of nano silicon powder and 0.1g of carbon nanotubes to the composite binder solution prepared above, magnetically stir and ultrasonically disperse to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, and dry it in vacuum at 100°C for 12 hours, then punch it into a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C, and place it In a glove box filled with argon gas, a lithium sheet was used as the counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) was used as the electrolyte, and a celgard2400 separator was used as the separator to assemble the half-cell.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C. The first reversible capacity reaches more than 2200mA h/g, and after 50 cycles it remains above 1900mA h/g. The cycle efficiency is more than 86%. The efficiency is always above 98%. The cycle performance test curve is shown in Figure 2.

Example 3

The lithium-ion battery-enhanced composite binder in this embodiment is composed of 0.05 g of carboxyl-functionalized carbon nanotubes and 0.1 g of sodium carboxymethyl cellulose.

The preparation method of carboxyl functionalized carbon nanotubes in this embodiment comprises the following steps:

(1) Prepare 120mL of mixed solution of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 2:1;

(2) Add 2g of carbon nanotubes to the mixture, ultrasonicate for 24 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 80°C for 10 hours, remove the supernatant after the obtained solution is centrifuged, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery-enhanced composite adhesive in the present embodiment comprises the following steps:

(1) Add 0.1 g of sodium carboxymethyl cellulose to 6 mL of deionized water to obtain a uniform, transparent viscous solution;

(2) Add 0.05 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite binder solution.

The application of the enhanced composite binder in the lithium-ion battery in the present embodiment comprises the following steps:

(1) Add 0.2g nano silicon powder and 0.1g carbon fiber to the composite binder solution prepared above, magnetically stir and ultrasonically disperse to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, dry it in vacuum at 100°C for 6 hours, then punch it to make a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C and place it In a glove box filled with argon gas, a lithium sheet was used as the counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) was used as the electrolyte, and a celgard2400 separator was used as the separator to assemble the half-cell.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C. The first reversible capacity reaches more than 2000mA h/g, and it remains above 1700mA h/g after 50 cycles. The cycle efficiency is more than 85%. The efficiency is always above 97%. The cycle performance test curve is shown in Figure 3.

Example 4

The lithium-ion battery-enhanced composite adhesive in this embodiment is composed of 0.05 g of carboxyl-functionalized carbon nanotubes and 0.1 g of sodium carboxymethyl starch.

The preparation method of carboxyl functionalized carbon nanotubes in this embodiment comprises the following steps:

(1) Prepare 120mL of a mixture of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:2

(2) Add 2g of carbon nanotubes to the mixture, ultrasonicate for 6 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 60°C for 12 hours, remove the supernatant after centrifuging the obtained solution, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery-enhanced composite adhesive in the present embodiment comprises the following steps:

(1) Add 0.1 g of sodium carboxymethyl starch into 6 mL of deionized water to obtain a uniform, transparent viscous solution;

(2) Add 0.05 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite binder solution.

The application of the enhanced composite binder in the lithium-ion battery in the present embodiment comprises the following steps:

(1) Add 0.3g of nano-silica powder and 0.15g of carbon fiber to the composite binder solution prepared above, magnetically stir and ultrasonically disperse to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, dry it in vacuum at 100°C for 6 hours, then punch it to make a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C and place it In a glove box filled with argon gas, a lithium sheet was used as the counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) was used as the electrolyte, and a celgard2400 separator was used as the separator to assemble the half-cell.

In this example, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C, the first reversible capacity reaches more than 2100mA h/g, and after 50 cycles it remains above 1700mA h/g, and the cycle efficiency is more than 80%. The efficiency is always above 96%.

Example 5

The lithium-ion battery-enhanced composite binder in this example is composed of 0.01 g of carboxyl-functionalized carbon nanotubes and 0.1 g of carboxymethyl chitin.

The preparation method of carboxyl functionalized carbon nanotubes in this embodiment comprises the following steps:

(1) Prepare 120mL of a mixture of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:2

(2) Add 4g of carbon nanotubes to the mixture, ultrasonicate for 6 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 60°C for 12 hours, remove the supernatant after the obtained solution is centrifuged, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery-enhanced composite adhesive in the present embodiment comprises the following steps:

(1) Add 0.1g carboxymethyl chitin to 6mL deionized water to obtain a uniform, transparent viscous solution;

(2) Add 0.01 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite adhesive solution.

The application of the enhanced composite binder in the lithium-ion battery in the present embodiment comprises the following steps:

(1) Add 0.5g nano-silica powder and 0.05g nickel fiber to the composite binder solution prepared above, magnetically stir and ultrasonically disperse to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, dry it in vacuum at 100°C for 6 hours, then punch it to make a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C and place it In a glove box filled with argon gas, a lithium sheet was used as the counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) was used as the electrolyte, and a celgard2400 separator was used as the separator to assemble the half-cell.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C, and the reversible specific capacity reaches above 1900mA h/g for the first time, and remains above 1500mA h/g after 50 cycles, and the cycle efficiency is above 78%. The Coulombic efficiency has always remained above 96%.

Example 6

The lithium-ion battery-reinforced composite binder in this example is composed of 0.05 g of carboxy-functionalized carbon nanotubes and 0.1 g of croscarmellose sodium.

The preparation method and application of the lithium-ion battery reinforced composite adhesive in this example are the same as in Example 3, except for vacuum drying at 150° C. for 1 hour after coating.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C. The first reversible capacity reaches more than 2300mA h/g, and it remains above 2100mA h/g after 50 cycles. The cycle efficiency is more than 91%. The efficiency is always above 98%.

Example 7

The lithium-ion battery-reinforced composite binder in this example is composed of 0.01 g of carboxyl-functionalized carbon nanotubes and 0.1 g of sodium carboxymethylcellulose-sodium carboxymethyl starch cross-linked product.

The preparation method of carboxyl functionalized carbon nanotubes in this embodiment comprises the following steps:

(1) Prepare 120mL of mixed solution of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:1;

(2) Add 3g of carbon nanotubes to the mixture, ultrasonicate for 8 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 120°C for 2 hours, remove the supernatant after centrifuging the obtained solution, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery-enhanced composite adhesive in the present embodiment comprises the following steps:

(1) Add 0.05g sodium carboxymethylcellulose and 0.05g sodium carboxymethyl starch into 16mL deionized water to obtain a uniform, transparent viscous solution;

(2) Add 0.01 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite adhesive solution.

The application of the enhanced composite binder in the lithium-ion battery in the present embodiment comprises the following steps:

(1) 0.3g nano-silica powder, 0.1g superconducting carbon black, crosslinking agent (polyacrylic acid), initiator (potassium persulfate) are added in the composite binder solution prepared above, magnetically stirred and ultrasonically dispersed, Obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, dry it in vacuum at 120°C for 2 hours, punch it out to make a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C and place it In a glove box filled with argon gas, a lithium sheet was used as the counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) was used as the electrolyte, and a celgard2400 separator was used as the separator to assemble the half-cell.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C. The first reversible capacity reaches more than 2300mA h/g, and it remains above 2000mA h/g after 50 cycles. The cycle efficiency is more than 86%. The efficiency is always above 97%.

Comparative example 1

The lithium ion battery composite binder in this comparative example is composed of 0.05g of carbon nanotubes and 0.1g of sodium alginate.

The preparation method of lithium-ion battery composite adhesive in this comparative example may further comprise the steps:

(1) Add 0.1g sodium alginate to 6mL deionized water to obtain a uniform, transparent viscous solution;

(2) Add 0.05 g of carbon nanotubes into the solution in step (1), and sonicate until uniform to obtain a composite adhesive solution.

The application of composite binder in lithium-ion battery in this comparative example comprises the following steps:

(1) Add 0.3g nano-silica powder and 0.1g superconducting carbon black to the composite binder solution prepared above, magnetically stir and ultrasonically disperse to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, dry it in vacuum at 150°C for 6 hours, punch it out to make a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 120°C and place it In a glove box filled with argon, a half-cell was assembled with a lithium sheet as a counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) as an electrolyte, and a celgard2400 separator as a separator.

In this comparative example, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C. The first reversible capacity reaches more than 2200mA h/g, and it remains above 1500mA h/g after 50 cycles. The cycle efficiency is above 68%. After charging and discharging at a high rate, the Coulombic efficiency decreases to about 95%. The cycle performance test curve is shown in Figure 4.

Comparative example 2

The lithium ion battery composite binder in this comparative example is composed of 0.05g carboxyl functionalized carbon nanotubes and 0.1g PVDF.

The preparation method of carboxyl functionalized carbon nanotubes in this comparative example comprises the following steps:

(1) Prepare 120mL of mixed solution of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:1;

(2) Add 3g of carbon nanotubes to the mixture, ultrasonicate for 8 hours at a frequency of 22kHz and a power of 500W, then stir and reflux at 120°C for 2 hours, remove the supernatant after the obtained solution is centrifuged, and add deionized water to shake After uniformity, centrifuge again, repeat the operation until the pH value of the supernatant is greater than 6.5, and vacuum-dry at 120°C to obtain the final product.

The preparation method of lithium-ion battery composite adhesive in this comparative example may further comprise the steps:

(1) Add 0.1g PVDF to 8mL NMP to obtain a uniform and transparent solution;

(2) Add 0.05 g of the carboxy-functionalized carbon nanotubes prepared above into the solution in step (1), and sonicate until uniform to obtain a composite binder solution.

The application of composite binder in lithium-ion battery in this comparative example comprises the following steps:

(1) 0.2g nano-silica powder and 0.2g carbon nanotubes are added to the composite binder solution prepared above, and ball milled (12 hours) to obtain a uniform mixed slurry;

(2) Coat the mixed slurry in step (1) on the copper foil, and dry it in vacuum at 100°C for 12 hours, then punch it into a circular negative electrode sheet with a radius of 14mm and a thickness of 30μm, dry it in vacuum at 100°C, and place it In a glove box filled with argon, a half-cell was assembled with a lithium sheet as a counter electrode, 1M lithium hexafluorophosphate (EC:DEC:DMC=1:1:1, V/V) as an electrolyte, and a celgard2400 separator as a separator.

In this embodiment, the lithium-ion half-battery is charged and discharged at a current of 0.1C to 1C, and the reversible capacity reaches above 2200mA h/g for the first time, and remains above 350mA h/g after 50 cycles, and the cycle efficiency is as low as 16%. The performance test curve is shown in Figure 5.

Claims (10)

1. a lithium ion battery enhancement type composite adhesive, it is characterized in that: be made up of carboxyl function carbon nano tube and the water-soluble polymer containing A, B two kinds of groups, A group is carboxyl, and B group is hydroxyl and/or amino, and the mass ratio of described carbon nanotube and water-soluble polymer is 0.1 ~ 1.

2. lithium ion battery enhancement type composite adhesive according to claim 1, it is characterized in that: the preparation method of described carboxyl function carbon nano tube is: carbon nanotube is added in the mixed solution of the vitriol oil and concentrated nitric acid, reflux 2 ~ 12 hours at 60 ~ 120 DEG C after ultrasonic, washing, drying.

3. lithium ion battery enhancement type composite adhesive according to claim 2, is characterized in that: in described mixed solution, the volume ratio of the vitriol oil and concentrated nitric acid is 3:(1 ~ 2).

4. lithium ion battery enhancement type composite adhesive according to claim 1, it is characterized in that: described water-soluble polymer is any one in sodium alginate, Xylo-Mucine, cm-chitosan, carboxymethyl chitin, sodium starch glycolate, or the above-mentioned cross-linked hydrogel that several are formed.

5. a preparation method for the lithium ion battery enhancement type composite adhesive according to any one of Claims 1 to 4, is characterized in that: comprise the following steps: carboxyl function carbon nano tube and water-soluble polymer are added to the water, mix.

6. the application of lithium ion battery enhancement type composite adhesive in lithium cell according to any one of Claims 1 to 4.

7. the application of enhancement type composite adhesive according to claim 6 in lithium cell, is characterized in that: the consumption of composite adhesive is 20 ~ 50% of negative active core-shell material quality.

8. the application of enhancement type composite adhesive according to claim 6 in lithium cell, is characterized in that: described negative active core-shell material is carbon class, silicon class, tin class and matrix material thereof.

9. the application of enhancement type composite adhesive according to claim 8 in lithium cell, is characterized in that: described negative active core-shell material is one or more in natural graphite, electrographite, MCMB, biomass charcoal, nano-silicon, silicon-carbon mixture, silicon alloy, Si oxide, tin-based oxide, tin-based alloy, tin carbon complex.

10. the application of enhancement type composite adhesive according to claim 6 in lithium cell, is characterized in that: containing conductive agent in the electrode materials of described lithium cell, the consumption of conductive agent is 10 ~ 50% of negative active core-shell material quality.