A supercapacitor slurry, its preparation method and application

Abstract

The application relates to a super capacitor slurry and a preparation method and application thereof, and belongs to the technical field of super capacitors. The super capacitor slurry is a green and environment-friendly water-based slurry. By limiting the feeding sequence and feeding amount, and limiting the stirring speed and the dispersing speed, the super capacitor slurry can keep a good viscosity state during the preparation process, the friction between the powder particles can be fully utilized for dispersion, a super capacitor special slurry with good dispersing performance and high solid content is obtained, the pole piece coated by using the slurry has the characteristics of good uniformity, strong flexibility, high surface gloss and large area density, the super capacitor electrode piece prepared by using the super capacitor slurry is used to prepare a super capacitor single body, the product has high product performance consistency, and the service life of the super capacitor can be effectively prolonged in the actual use process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supercapacitors, and particularly relates to a supercapacitor slurry as well as a preparation method and application thereof. BACKGROUND

[0002] Compared with a battery, a supercapacitor has a greater power density, and compared with a traditional capacitor, the supercapacitor has a higher energy density. The supercapacitor is a new type of energy storage electronic component between the battery and the traditional capacitor, and generally has a carbon-based double-layer structure and is mainly composed of an electrode sheet, an electrolyte, a separator and the like. The supercapacitor stores energy in a physical manner through electrostatic adsorption, and no chemical reaction occurs during the storage. Therefore, the supercapacitor has the characteristics of high power performance, long cycle life and high safety, and has a strong application potential in the fields of small electronic devices, new energy vehicles, military equipment, aerospace and the like.

[0003] At present, the main factors restricting the development of supercapacitors are low energy density and low single working voltage. Therefore, the mainstream application of the supercapacitor at present is to form a module through series and parallel connection, and to be used in cooperation with a lithium ion battery, so as to respectively give play to the advantages of high energy density of the lithium ion battery and high power density of the supercapacitor, and to achieve an effect of one plus one greater than two. However, when the supercapacitor gives play to the advantage of high power density, the size of internal resistance is a key factor affecting the performance of the supercapacitor. When a large current is passed through an electric appliance, if the internal resistance is too large, a large pressure drop of the supercapacitor will be caused, thereby affecting the normal use of the supercapacitor. Therefore, how to improve the energy density of the supercapacitor and how to reduce the internal resistance of the supercapacitor are currently hot research topics in the industry.

[0004] The quality of the electrode sheet of the supercapacitor is a key factor directly affecting the final capacity and the size of internal resistance of the supercapacitor. Therefore, the preparation of the electrode sheet is a core process of the supercapacitor, and the key of the electrode sheet is a slurry. The slurry used in the existing supercapacitor electrode sheet is usually organic matter such as N-methyl pyrrolidone, dimethyl sulfoxide and dimethyl formamide as a solvent. Patent CN105551821A provides a supercapacitor slurry, which uses N-methyl pyrrolidone as a solvent, puts the solute and the solvent into a blender to form a non-flowing viscous material, and then forms a supercapacitor slurry with a certain viscosity through extrusion mixing and ultrasonic stirring, and the solid content of the slurry is between 10% and 25%. However, due to the large polarity, high cost and large environmental pollution of N-methyl pyrrolidone, the slurry prepared by using this solvent is not only not environmentally friendly, but also cannot well control the dispersion effect of the solute during the preparation process, resulting in that the solid content of the slurry is usually low and the performance is poor. Therefore, it is urgent to develop and design a water-based supercapacitor slurry which is green, environmentally friendly, high-performance, has high dispersion and high solid content. SUMMARY

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a green and environmentally friendly water-based supercapacitor slurry with high solid content and good dispersibility. The supercapacitor prepared from this slurry has high capacity, low internal resistance and high product performance consistency.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a supercapacitor slurry comprising the following components by mass percentage: 60-70% solvent and 30-40% solute;

[0008] The solvent comprises the following components by mass percentage: 96-99% water and 1-4% N-methylpyrrolidone;

[0009] The solute comprises the following components by mass percentage: 82-87% activated carbon, 7-12% conductive carbon material, 4-5% sodium carboxymethyl cellulose and 1-2% styrene-butadiene rubber.

[0010] The supercapacitor slurry of this invention uses water as the main solvent. Through specific addition amounts and sequences, the slurry maintains a good viscosity throughout the preparation process, fully utilizing the frictional force between powders for dispersion. This results in a supercapacitor slurry with excellent dispersion performance and a solid content as high as 30%–40%. Furthermore, the use of water-based solvent in this invention, compared to traditional methods that use large amounts of the organic solvent N-methylpyrrolidone, makes the supercapacitor slurry of this invention more environmentally friendly. It also improves the capacity and reduces the internal resistance of the supercapacitor cells prepared from it, effectively enhancing the energy density and electrical performance of the supercapacitor cells.

[0011] In a preferred embodiment of the supercapacitor paste of the present invention, the conductive carbon material includes at least one of carbon black, graphene, and carbon nanotubes.

[0012] In a preferred embodiment of the supercapacitor slurry of the present invention, the solid content of the supercapacitor slurry is 30-40%.

[0013] In a preferred embodiment of the supercapacitor slurry of the present invention, the viscosity of the supercapacitor slurry is 1800-3000 mPa·S, and the fineness of the supercapacitor slurry is ≤30 μm.

[0014] Secondly, the present invention provides a method for preparing the above-mentioned supercapacitor slurry, comprising the following steps:

[0015] (1) Divide the water into five parts and the activated carbon into two parts;

[0016] (2) Add the first portion of water and sodium carboxymethyl cellulose to the stirring device. After the addition is completed, set the revolution speed of the stirring device to 30-45 r / min and the dispersion speed to 2800-3500 r / min. Stir for 30-40 min to obtain mixture A.

[0017] (3) Add conductive carbon material, N-methylpyrrolidone and a second part of water to the mixture A described in step (2). After the addition is completed, set the revolution speed of the stirring device to 30-45 r / min and the dispersion speed to 2800-3500 r / min, and stir for 120-150 min to obtain mixture B.

[0018] (4) Add the first part of activated carbon and the third part of water to the mixture B described in step (3). After the addition is completed, set the revolution speed of the stirring device to 30-45 r / min and the dispersion speed to 2800-3500 r / min. Stir for 120-150 min to obtain mixture C.

[0019] (5) Add the second part of activated carbon and the fourth part of water to the mixture C described in step (4). After the addition is completed, set the revolution speed of the stirring device to 30-45 r / min and the dispersion speed to 2800-3500 r / min, and stir for 300-360 min to obtain the mixture D.

[0020] (6) Add styrene-butadiene rubber and the fifth part of water to the mixture D in step (5). After the addition is completed, set the revolution speed of the stirring device to 30-45 r / min and the dispersion speed to 2800-3500 r / min, and stir for 120-150 min to obtain the supercapacitor slurry.

[0021] Through extensive research, the inventors of this invention have discovered that, in the process of preparing supercapacitor slurry, this invention employs a specific feeding sequence and a specific feeding amount, while simultaneously controlling the stirring speed and dispersion speed. Compared to other methods of preparing supercapacitor slurry by adding all raw materials at once or using other feeding methods, the supercapacitor slurry preparation method of this invention can maintain the slurry in a good viscosity state at all times. This allows for full utilization of the frictional force between powder particles, resulting in uniform dispersion of the supercapacitor slurry and effectively solving the problems of easy stratification and poor dispersion effect in supercapacitor slurry. In addition, the supercapacitor slurry prepared using this invention also has high solid content and excellent conductivity, and can obtain electrode sheets with high areal density. Under the same specifications, it can effectively save the area of ​​supercapacitor electrode sheets used.

[0022] As a preferred embodiment of the method for preparing the supercapacitor slurry of the present invention, the first part of water has a mass fraction of 71-75%, the second part of water has a mass fraction of 1-5%, the third part of water has a mass fraction of 4-8%, the fourth part of water has a mass fraction of 5-9%, and the fifth part of water has a mass fraction of 3-7%.

[0023] Based on the total mass of activated carbon, the first batch of activated carbon has a mass fraction of 50%, and the second batch of activated carbon has a mass fraction of 50%.

[0024] The method for preparing supercapacitor slurry according to the present invention divides water into five parts and limits its mass fraction, and divides activated carbon into two equal parts. At the same time, it controls the order of addition of each component, which can better control the dispersion of supercapacitor slurry during the preparation process when the solid content is high. It completely overcomes the defects of traditional methods, such as agglomeration, inability to stir normally and discharge material due to the one-time addition of water or other components.

[0025] Thirdly, the present invention also provides the application of the above-mentioned supercapacitor paste in supercapacitor electrode sheets.

[0026] The present invention provides a supercapacitor electrode sheet, which is formed by coating the supercapacitor slurry onto a current collector and then curing it.

[0027] The supercapacitor electrode sheet obtained by the supercapacitor slurry preparation method described in this invention has high product performance consistency, thereby effectively extending the service life of the supercapacitor in actual use. In addition, the supercapacitor cell prepared by the supercapacitor electrode sheet described in this invention has higher capacity and lower internal resistance compared with commercially available products of the same specifications. Currently, the internal resistance of commercially available 2.7V 3F products is 120-180mΩ, the internal resistance of 2.7V 10F products is 75-90mΩ, and the internal resistance of 2.7V 20F products is 30-45mΩ. The internal resistance of the supercapacitor cell prepared by the supercapacitor electrode sheet described in this invention can be reduced by 1-3 times, thereby further improving the electrical performance of the supercapacitor.

[0028] In a preferred embodiment of the supercapacitor electrode sheet of the present invention, the supercapacitor electrode sheet is a single-sided electrode sheet or a double-sided electrode sheet; the thickness of the single-sided electrode sheet is 80-150 μm, and the thickness of the double-sided electrode sheet is 160-300 μm.

[0029] The present invention provides a supercapacitor, the supercapacitor comprising the supercapacitor electrode sheet described above.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) The supercapacitor slurry of the present invention maintains a good viscosity state during the preparation process by using a specific amount and order of feeding, making full use of the friction between powders to disperse them, and finally obtaining a supercapacitor slurry with good dispersion performance and a solid content of up to 30-40%. The supercapacitor cells prepared from it have higher capacity and lower internal resistance, effectively improving the energy density and electrical performance of the supercapacitor cells.

[0032] (2) The supercapacitor slurry preparation method provided by the present invention, by limiting the order and amount of addition of components, and controlling the stirring speed and dispersion speed, the supercapacitor slurry prepared has the characteristics of high solid content and excellent dispersion performance, and can obtain electrode sheets with high surface density. Under the same specifications, it can effectively save the area of ​​supercapacitor electrode sheets.

[0033] (3) The supercapacitor electrode sheet obtained by the supercapacitor slurry preparation method described in this invention has high product performance consistency, thereby extending the life of the supercapacitor in actual use.

[0034] (4) The supercapacitor cell prepared by the supercapacitor electrode sheet described in this invention has higher capacity and lower internal resistance than commercially available products of the same specifications, which can effectively improve the energy density and electrical performance of the supercapacitor. Attached Figure Description

[0035] Figure 1 This is a diagram of the supercapacitor slurry prepared in Comparative Example 1 of this invention;

[0036] Figure 2 This is a diagram of the supercapacitor slurry prepared in Comparative Example 2 of the present invention;

[0037] Figure 3 This is a diagram of the supercapacitor slurry prepared in Comparative Example 3 of the present invention;

[0038] Figure 4 NDJ-5S digital viscometer for testing slurry viscosity;

[0039] Figure 5 QXD type scraper fineness gauge for testing the fineness of slurry;

[0040] Figure 6 This is a SEM image of the electrode cross-section;

[0041] Figure 7 This is a diagram of the coated supercapacitor electrode sheet according to the present invention;

[0042] Figure 8 This is a SEM image of the particle distribution of the supercapacitor electrode sheet prepared in Example 1 of the present invention;

[0043] Figure 9 This is a SEM image of the particle distribution of the supercapacitor electrode sheet prepared in Example 2 of the present invention;

[0044] Figure 10 This is a SEM image of the particle distribution of the supercapacitor electrode sheet prepared in Comparative Example 4 of the present invention.

[0045] Figure 11 This is a SEM image of the particle distribution of the supercapacitor electrode sheet prepared in Comparative Example 5 of the present invention.

[0046] Figure 12 The diagram shows the capacitance performance of the 2.7V 3F supercapacitor cells prepared by Examples 1-2 and Comparative Examples 4-5 according to the present invention.

[0047] Figure 13 The resistivity diagram shows the resistance performance of the 2.7V 3F supercapacitor cells prepared by Examples 1-2 and Comparative Examples 4-5 according to the present invention.

[0048] Figure 14 The diagram shows the capacitance performance of the 2.7V 10F supercapacitor cells prepared by Examples 1-2 and Comparative Examples 4-5 according to the present invention.

[0049] Figure 15 The resistivity diagram shows the resistance performance of the 2.7V 10F supercapacitor cells prepared by Examples 1-2 and Comparative Examples 4-5 of this invention.

[0050] Figure 16 The diagram shows the capacitance performance of the 2.7V 20F supercapacitor cells prepared by Examples 1-2 and Comparative Examples 4-5 according to the present invention.

[0051] Figure 17 The resistivity diagram shows the resistance performance of the 2.7V 20F supercapacitor cells prepared by Examples 1-2 and Comparative Examples 4-5 according to the present invention. Detailed Implementation

[0052] The technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the methods or operations used in the embodiments are conventional methods or operations in the art.

[0053] Example 1

[0054] One embodiment of the supercapacitor paste of the present invention, wherein the preparation method of the supercapacitor paste in this embodiment is as follows:

[0055] (1) Weigh 7077.5g of water, 140g of N-methylpyrrolidone, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber. Divide the water into five portions: the first to fifth portions of water have masses of 5200g, 340g, 500g, 590g and 447.5g respectively. Divide the activated carbon into two portions: the first and second portions of activated carbon each have a mass of 1932g.

[0056] (2) Add the first portion of water and sodium carboxymethyl cellulose to the mixing tank of the vacuum mixer. After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to , and the mixture is stirred for 30 min to obtain mixture A.

[0057] (3) Add acetylene black, N-methylpyrrolidone and a second part of water to the mixture A in step (2). After the addition is completed, vacuum is applied, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain mixture B.

[0058] (4) Add the first part of activated carbon and the third part of water to the mixture B described in step (3). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 150 min to obtain mixture C.

[0059] (5) Add the second part of activated carbon and the fourth part of water to the mixture C described in step (4). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 300 min to obtain the mixture D.

[0060] (6) Add styrene-butadiene rubber and the fifth part of water to the mixture D in step (5). After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain the supercapacitor slurry.

[0061] Example 2

[0062] One embodiment of the supercapacitor paste of the present invention, wherein the preparation method of the supercapacitor paste in this embodiment is as follows:

[0063] (1) Weigh 7145.3g of water, 72.2g of N-methylpyrrolidone, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber. Divide the water into five portions: the first to fifth portions of water have masses of 5251g, 343g, 507.3g, 594g and 450g respectively. Divide the activated carbon into two portions: the first and second portions of activated carbon each have a mass of 1932g.

[0064] (2) Add the first portion of water and sodium carboxymethyl cellulose to the mixing tank of the vacuum mixer. After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 30 min to obtain mixture A.

[0065] (3) Add acetylene black, N-methylpyrrolidone and a second part of water to the mixture A in step (2). After the addition is completed, vacuum is applied, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain mixture B.

[0066] (4) Add the first part of activated carbon and the third part of water to the mixture B described in step (3). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 150 min to obtain mixture C.

[0067] (5) Add the second part of activated carbon and the fourth part of water to the mixture C described in step (4). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 300 min to obtain the mixture D.

[0068] (6) Add styrene-butadiene rubber and the fifth part of water to the mixture D in step (5). After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain the supercapacitor slurry.

[0069] Comparative Example 1

[0070] This invention provides a comparative example of a supercapacitor slurry. The preparation method of the supercapacitor slurry described in this comparative example is as follows:

[0071] (1) Weigh out 7077.5g of water, 140g of N-methylpyrrolidone, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber;

[0072] (2) Water, sodium carboxymethyl cellulose, N-methylpyrrolidone, acetylene black, activated carbon, and styrene-butadiene rubber were added to the mixing tank of the vacuum mixer. After the addition was completed, a vacuum was drawn, and the revolution speed of the mixing tank was set to 35 r / min. Clumping occurred, making normal mixing and discharging impossible. The supercapacitor slurry in this comparative example is as follows: Figure 1 As shown.

[0073] Comparative Example 2

[0074] This invention provides a comparative example of a supercapacitor slurry. The preparation method of the supercapacitor slurry described in this comparative example is as follows:

[0075] (1) Weigh 7077.5g of water, 140g of N-methylpyrrolidone, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber, and divide the activated carbon into two portions: the first portion of activated carbon and the second portion of activated carbon each weigh 1932g.

[0076] (2) Add water and sodium carboxymethyl cellulose to the mixing tank of the vacuum mixer. After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to , and the mixture is stirred for 30 min to obtain mixture A.

[0077] (3) Add acetylene black and N-methylpyrrolidone to the mixture A in step (2). After the addition is completed, vacuum is applied, the revolution speed of the stirring tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain mixture B.

[0078] (4) Add the first part of activated carbon to the mixture B in step (3). After the addition is completed, vacuum is drawn, the revolution speed of the stirring tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the stirring is carried out for 150 min to obtain mixture C.

[0079] (5) Add the second part of activated carbon to the mixture C described in step (4). After the addition is completed, clumping occurs, making subsequent stirring and discharge impossible. The supercapacitor slurry in this comparative example is as follows: Figure 2 As shown.

[0080] Comparative Example 3

[0081] This invention provides a comparative example of a supercapacitor slurry. The preparation method of the supercapacitor slurry described in this comparative example is as follows:

[0082] (1) Weigh 7077.5g of water, 140g of N-methylpyrrolidone, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber, and divide the water into four portions: the mass of the first to fourth portions of water are 5200g, 340g, 1090g and 447.5g respectively;

[0083] (2) Add the first portion of water and sodium carboxymethyl cellulose to the mixing tank of the vacuum mixer. After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to , and the mixture is stirred for 30 min to obtain mixture A.

[0084] (3) Add acetylene black, N-methylpyrrolidone and a second part of water to the mixture A in step (2). After the addition is completed, vacuum is applied, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain mixture B.

[0085] (4) Add activated carbon and a third part of water to the mixture B described in step (3). After the addition is completed, the activated carbon quickly absorbs the water, causing clumping and making it impossible to stir and discharge normally. The supercapacitor slurry in this comparative example is as follows: Figure 3 As shown.

[0086] Comparative Example 4

[0087] This invention provides a comparative example of a supercapacitor slurry. The preparation method of the supercapacitor slurry described in this comparative example is as follows:

[0088] (1) Weigh 7217.5g of water, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber. Divide the water into five parts: the first to fifth parts of water have masses of 5200g, 340g, 500g, 590g and 447.5g respectively. Divide the activated carbon into two parts: the first and second parts of activated carbon each have a mass of 1932g.

[0089] (2) Add the first portion of water and sodium carboxymethyl cellulose to the mixing tank of the vacuum mixer. After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to , and the mixture is stirred for 30 min to obtain mixture A.

[0090] (3) Add acetylene black and the second part of water to the mixture A in step (2). After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain mixture B.

[0091] (4) Add the first part of activated carbon and the third part of water to the mixture B described in step (3). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 150 min to obtain mixture C.

[0092] (5) Add the second part of activated carbon and the fourth part of water to the mixture C described in step (4). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 300 min to obtain the mixture D.

[0093] (6) Add styrene-butadiene rubber and the fifth part of water to the mixture D in step (5). After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain the supercapacitor slurry.

[0094] Comparative Example 5

[0095] This invention provides a comparative example of a supercapacitor slurry. The preparation method of the supercapacitor slurry described in this comparative example is as follows:

[0096] (1) Weigh 7182.5g of water, 35g of N-methylpyrrolidone, 3864g of activated carbon, 460g of acetylene black, 78g of sodium methylcellulose and 202.5g of styrene-butadiene rubber. Divide the water into five parts: the first to fifth parts of water have masses of 5279g, 345g, 510g, 596g and 452.5g respectively. Divide the activated carbon into two parts: the first and second parts of activated carbon each have a mass of 1932g.

[0097] (2) Add the first portion of water and sodium carboxymethyl cellulose to the mixing tank of the vacuum mixer. After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 30 min to obtain mixture A.

[0098] (3) Add acetylene black, N-methylpyrrolidone and a second part of water to the mixture A in step (2). After the addition is completed, vacuum is applied, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain mixture B.

[0099] (4) Add the first part of activated carbon and the third part of water to the mixture B described in step (3). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 150 min to obtain mixture C.

[0100] (5) Add the second part of activated carbon and the fourth part of water to the mixture C described in step (4). After the addition is completed, vacuum is applied, and the revolution speed of the mixing tank is set to 35 r / min and the dispersion speed is set to 3000 r / min. Stir for 300 min to obtain the mixture D.

[0101] (6) Add styrene-butadiene rubber and the fifth part of water to the mixture D in step (5). After the addition is completed, vacuum is drawn, the revolution speed of the mixing tank is set to 35 r / min, the dispersion speed is set to 3000 r / min, and the mixture is stirred for 120 min to obtain the supercapacitor slurry.

[0102] Example of effect 1

[0103] The viscosity and fineness of the supercapacitor slurries prepared in Examples 1-2 and Comparative Examples 4-5 of this invention were tested. The specific testing methods are as follows. The formula for calculating the solid content of the supercapacitor slurries prepared in Examples 1-2 and Comparative Examples 4-5 of this invention is: Solid content = Solute / (Solvent + Solute):

[0104] (1) Viscosity test: Measured using an NDJ-5S digital viscometer;

[0105] (2) Fineness test: The fineness was measured using a QXD type scraper fineness gauge.

[0106] The test results are shown in Table 1.

[0107] Table 1

[0108] Viscosity / mPa-s Fineness / pm Solid content / % Example 1 2670 ＜30 39 Example 2 2376 ＜30 39 Comparative Example 4 2236 ＞100 39 Comparative Example 5 2312 ＞80 39

[0109] As can be seen from Table 1, when the solid content of the slurry is 39%, the fineness of the supercapacitor slurry prepared by the preparation method of the present invention is less than 30 μm, while the fineness of the supercapacitor slurry prepared by Comparative Examples 4-5 is above 80 μm, indicating that the supercapacitor slurry prepared by the method of the present invention has better dispersibility.

[0110] Example 2

[0111] Preparation of supercapacitor electrodes: Using a coating machine, the supercapacitor slurries prepared in Examples 1-2 and Comparative Examples 4-5 of this invention were coated on both sides to obtain supercapacitor electrodes using the slurries. The areal densities of the supercapacitor electrodes in Examples 1-2 and Comparative Examples 4-5 were 0.0168 g / cm³, respectively. 2 0.0165g / cm 2 0.0151g / cm 2 0.0154 g / cm 2 .

[0112] The coated supercapacitor electrode sheet is as follows Figure 7 As shown, the particle distributions of the supercapacitor electrodes prepared in Examples 1-2 and Comparative Examples 4-5 are respectively as follows: Figures 8-11 As shown. By Figure 8 , Figure 9 , Figure 10 , Figure 11 It can be seen that the supercapacitor obtained by the supercapacitor slurry preparation method described in this invention can be uniformly and with high areal density coated on the current collector, that is... Figure 8 , Figure 9 The electrode shown exhibits the best uniformity and areal density.

[0113] Preparation of 2.7V 3F supercapacitor cells: The supercapacitor electrode sheets were rolled to a thickness of 182.7μm using a rolling mill. They were then slit into thin strips with a width of 14mm using a slitting machine. The effective length of the negative electrode was 31mm and the effective length of the positive electrode was 46mm. Leads were introduced into the positive and negative electrodes respectively. The cells were then wound together to form a cell. The cells were then baked and then fully automated impregnation and sealing were performed under drying conditions with a dew point temperature of -55℃ to obtain 2.7V 3F supercapacitor cells. All of the above processes were carried out in a drying room.

[0114] Following the above method, ten 2.7V 3F supercapacitor cells were prepared using different electrodes. Their capacitance and internal resistance were then tested, and the results are as follows: Figure 12 and Figure 13 As shown. By Figure 12 and Figure 13 It can be seen that the supercapacitor cells of Examples 1 and 2 all have a capacitance of over 3.4F, a capacitance variance within 0.001, an internal resistance within 54mΩ, and an internal resistance variance within 0.04. In contrast, Comparative Example 4 has a maximum capacitance of 3.29F, a minimum capacitance of 2.8F, a capacitance variance of 0.2, a maximum internal resistance of 85.7mΩ, a minimum internal resistance of 81.2mΩ, and an internal resistance variance of 2.83. Comparative Example 5 has a maximum capacitance of 3.23F, a minimum capacitance of 3.1F, a capacitance variance of 0.25, a maximum internal resistance of 78.4mΩ, a minimum internal resistance of 72.5mΩ, and an internal resistance variance of 2.04. Through data comparison and analysis, it can be seen that the supercapacitors prepared using the slurry of this invention exhibit high capacitance, low internal resistance, and high consistency, which can effectively improve the energy density and electrical performance of the supercapacitor cell samples and extend the product's service life.

[0115] Example 3

[0116] The preparation method of the supercapacitor electrode sheet in this example is the same as that in Example 2.

[0117] Preparation of 2.7V 10F supercapacitor cells: The supercapacitor electrode sheets were rolled to a thickness of 182.7μm using a rolling mill. They were then slit into thin strips with a width of 18mm using a slitting machine. The effective length of the negative electrode was 79mm and the effective length of the positive electrode was 97mm. Leads were introduced into the positive and negative electrodes respectively. The cells were then wound together to form a cell. The cells were then baked and then fully automated impregnation and sealing were performed under drying conditions with a dew point temperature of -55℃ to obtain 2.7V 10F supercapacitor cells. All of the above processes were carried out in a drying room.

[0118] Following the above method, ten 2.7V 10F supercapacitor cells were prepared using different electrodes. Their capacitance and internal resistance were tested, and the results are as follows: Figure 14 and Figure 15 As shown. By Figure 14 , Figure 15 It can be seen that in Examples 1 and 2, the capacitance is above 11.3F, the capacitance variance is within 0.001, the internal resistance is within 38mΩ, and the internal resistance variance is within 0.03. In Comparative Example 4, the maximum capacitance is 9.66F, the minimum capacitance is 9.38F, the capacitance variance is 0.1, the maximum internal resistance is 49.78mΩ, the minimum is 47.25mΩ, and the internal resistance variance is 0.6. In Comparative Example 5, the maximum capacitance is 9.89F, the minimum capacitance is 9.82F, the capacitance variance is 0.1, the maximum internal resistance is 43.89mΩ, the minimum is 41.58mΩ, and the internal resistance variance is 0.5. Through data comparison and analysis, it can be seen that the supercapacitors prepared using the slurry of this invention exhibit high capacitance, low internal resistance, and high consistency, which can effectively improve the energy density and electrical performance of the supercapacitor individual samples and extend the product's service life.

[0119] Example of effect 4

[0120] The preparation method of the supercapacitor electrode sheet in this example is the same as that in Example 2.

[0121] Preparation of 2.7V 20F supercapacitor cells: The supercapacitor electrode sheets were rolled to a thickness of 182.7μm using a rolling mill. They were then slit into thin strips with a width of 18mm using a slitting machine. The effective length of the negative electrode was 157mm and the effective length of the positive electrode was 177mm. Pins were introduced into the positive and negative electrodes respectively. The cells were assembled by winding and then baked. Subsequently, under drying conditions with a dew point temperature of -55℃, fully automated impregnation and sealing were performed to obtain 2.7V 20F supercapacitor cells. All of the above processes were carried out in a drying room.

[0122] Following the above method, ten 2.7V 20F supercapacitor cells were prepared using different electrodes. Their capacitance and internal resistance were then tested, and the results are as follows: Figure 16 and Figure 17 As shown. By Figure 16 , Figure 17 It can be seen that in Examples 1 and 2, the capacitance is above 22.4F, the capacitance variance is within 0.0001, the internal resistance is within 38mΩ, and the internal resistance variance is within 0.03. In Comparative Example 4, the maximum capacitance is 19.45F, the minimum capacitance is 18.79F, the capacitance variance is 0.03, the maximum internal resistance is 36.53mΩ, the minimum is 34.42mΩ, and the internal resistance variance is 0.7. In Comparative Example 5, the maximum capacitance is 20.25F, the minimum capacitance is 20.01F, the capacitance variance is 0.01, the maximum internal resistance is 32.45mΩ, the minimum is 30.42mΩ, and the internal resistance variance is 0.6. Through data comparison and analysis, it can be seen that the supercapacitors prepared using the slurry of this invention exhibit high capacitance, low internal resistance, and high consistency, which can effectively improve the energy density and electrical performance of the supercapacitor individual samples and extend the product's service life.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A supercapacitor paste, characterized in that, It comprises the following components by mass percentage: 60-70% solvent and 30-40% solute; The solvent comprises the following components by mass percentage: 96-99% water and 1-4% N-methylpyrrolidone; The solute comprises the following components by mass percentage: 82-87% activated carbon, 7-12% conductive carbon material, 4-5% sodium carboxymethyl cellulose and 1-2% styrene-butadiene rubber; The method for preparing the supercapacitor paste includes the following steps: (1) Divide the water into five parts and the activated carbon into two parts; based on the total mass of water, the mass fraction of the first part of water is 71-75%, the mass fraction of the second part of water is 1-5%, the mass fraction of the third part of water is 4-8%, the mass fraction of the fourth part of water is 5-9%, and the mass fraction of the fifth part of water is 3-7%. Based on the total mass of activated carbon, the first batch of activated carbon has a mass fraction of 50%, and the second batch of activated carbon has a mass fraction of 50%. (2) Add the first portion of water and sodium carboxymethyl cellulose to the stirring device. After the addition is completed, set the revolution speed of the stirring device to 30~45 r / min and the dispersion speed to 2800~3500 r / min. Stir for 30~40 min to obtain mixture A; (3) Add conductive carbon material, N-methylpyrrolidone and a second part of water to the mixture A in step (2). After the addition is completed, set the revolution speed of the stirring device to 30~45 r / min and the dispersion speed to 2800~3500 r / min, and stir for 120~150 min to obtain mixture B; (4) Add the first part of activated carbon and the third part of water to the mixture B in step (3). After the addition is completed, set the revolution speed of the stirring device to 30~45 r / min and the dispersion speed to 2800~3500 r / min. Stir for 120~150 min to obtain mixture C. (5) Add the second part of activated carbon and the fourth part of water to the mixture C in step (4). After the addition is completed, set the revolution speed of the stirring device to 30~45 r / min and the dispersion speed to 2800~3500 r / min, and stir for 300~360 min to obtain the mixture D; (6) Add styrene-butadiene rubber and the fifth part of water to the mixture D in step (5). After the addition is completed, set the revolution speed of the stirring device to 30~45 r / min and the dispersion speed to 2800~3500 r / min, and stir for 120~150 min to obtain the supercapacitor slurry.

2. The supercapacitor paste as described in claim 1, characterized in that, The conductive carbon material includes at least one of carbon black, graphene, and carbon nanotubes.

3. The supercapacitor paste as described in claim 1, characterized in that, The solid content of the supercapacitor slurry is 30-40%.

4. The supercapacitor paste as described in claim 1, characterized in that, The viscosity of the supercapacitor slurry is 1800~3000 mPa·S, and the fineness of the supercapacitor slurry is ≤30μm.

5. The application of a supercapacitor paste as described in any one of claims 1 to 4 in a supercapacitor electrode sheet.

6. A supercapacitor electrode sheet, characterized in that, It is formed by coating the current collector with the supercapacitor paste according to any one of claims 1 to 4 and then curing it.

7. The supercapacitor electrode sheet as described in claim 6, characterized in that, The supercapacitor electrode sheet is a single-sided electrode sheet or a double-sided electrode sheet; the thickness of the single-sided electrode sheet is 80~150μm, and the thickness of the double-sided electrode sheet is 160~300μm.

8. A supercapacitor, characterized in that, The supercapacitor includes the supercapacitor electrode sheet as described in claim 6 or 7.

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