WO2019153907A1

WO2019153907A1 - Low internal resistance and high power graphene supercapacitor electrode sheet and preparation method therefor

Info

Publication number: WO2019153907A1
Application number: PCT/CN2018/122645
Authority: WO
Inventors: 阮殿波; 郑超; 于学文; 乔志军; 傅冠生
Original assignee: 宁波中车新能源科技有限公司
Priority date: 2018-02-07
Filing date: 2018-12-21
Publication date: 2019-08-15
Also published as: CN108470635A

Abstract

A graphene supercapacitor electrode sheet, in particular, a low internal resistance and high power graphene supercapacitor electrode sheet and a preparation method therefor, belonging to the technical field of new energy energy storage devices. The graphene electrode sheet comprises a current collector and a graphene electrode paste. The graphene electrode paste comprises the following in percentage by mass: 75-93% of graphene, 2-10% of a conductive agent, and 5-15% of a bonding agent. The current collector is a coated aluminum foil. The graphene electrode sheet has a thickness of 100 to 200 μm and an areal density of 0.5 to 0.7 g/cm³. The supercapacitor graphene electrode sheet has characteristics such as low internal resistance and high power. The supercapacitor graphene electrode sheet has characteristics such as low internal resistance and high power.

Description

Internal resistance, high power graphene supercapacitor electrode sheet and preparation method thereof

Technical field

[0001] The present invention relates to a graphene supercapacitor electrode sheet, and more particularly to a low internal resistance, high power graphene super capacitor electrode sheet and a preparation method thereof, and belongs to the technical field of new energy energy storage devices.

Background technique

[0002] Supercapacitors have high safety, millions of cycle life, ultra-high power characteristics, low temperature performance, and environmental friendliness, making them a powerful alternative to batteries. It is a national strategic emerging industry and a core energy storage device for core components and energy efficiency in new energy vehicles. However, the commercial supercapacitor has a small capacity and low energy density. The energy density of the traditional activated carbon-based electric double layer capacitor is near the limit, and the power density is difficult to further increase. It is urgent to develop new materials and develop new processes to achieve energy density and power density. A substantial increase.

[0003] Graphene has attracted great attention in the field of energy storage for more than ten years due to its high specific surface area, excellent electrical conductivity, high electron mobility and special two-dimensional flexible structure. Supercapacitors are considered to be the industry sector most likely to achieve graphene scale applications in the short term. Applied to supercapacitors, graphene can have the dual characteristics of “conductivity” and “energy storage”. A large number of experimental results confirm that graphene is an ideal electrode material for low internal resistance and high power super capacitors. However, the graphene material has a low density, a large liquid absorption, and a low solid content of the slurry. It is difficult to prepare a graphene electrode sheet by a conventional wet coating process.

Summary of invention

technical problem

Problem solution

Technical solution

[0004] The object of the present invention is to provide a high specificity B, low internal resistance, high power graphene supercapacitor electrode sheet for the technical problems existing in the graphene supercapacitor electrode sheet.

[0005] In order to achieve the above object, the technical solution of the present invention includes the following steps: A low internal resistance, high power stone a graphene supercapacitor electrode sheet, the graphene electrode sheet comprising a current collector and a graphene electrode slurry, wherein the graphene electrode paste comprises graphene having a mass percentage of 75-93%, a conductive agent of 2-10%, 5-15% binder, the current collector is coated aluminum foil.

[0006] To increase the power density of the graphene electrode, in addition to the structural design of the graphene electrode material, the interface structure design between the graphene carbon film and the current collector is also a major concern, and the interface contact resistance directly affects the internal resistance of the device. The graphene material has a low density and a large specific surface area, and the ordinary aluminum foil current collector is difficult to ensure the adhesion of the graphene carbon film to the current collector. Therefore, proper treatment of the aluminum current collector is necessary. Industrially, large-capacity supercapacitors are etched on the surface of aluminum foil. The etched aluminum foil is called a corrosion foil. The corrosion-resistant aluminum foil greatly improves the adhesion between the carbon film and the current collector due to its rough surface, and makes the capacitor Performance is more stable. However, after the aluminum foil is etched, the conductivity is lowered and the mechanical properties are lowered. The thickness of corroded aluminum foil in industrial applications is generally maintained above 20 pm, because the thickness of the corroded aluminum foil determines its mechanical properties, especially in the large-scale automated production of electric double layer capacitors. Corroded aluminum foil with a thickness of less than 20 pm is relatively easy to break. The development of new aluminum foils that are thinner and maintain high electrical conductivity, superior mechanical properties and flexibility are an effective way to reduce the internal resistance of the device and to reduce the mass occupied by the current collector and increase the specific energy of the device. A conductive carbon material is coated on the aluminum foil current collector to form a coated aluminum foil. The conductive coating improves adhesion between the electrode material and the current collector, extends device life, and reduces contact resistance inside the electrode, increasing device power density. Compared with corroded aluminum foil, coated aluminum foil has good mechanical properties and electrical conductivity. As a preferred collector of the present invention, a coated aluminum foil is selected.

[0007] In the above low internal resistance, high power graphene supercapacitor electrode sheet, the graphene electrode sheet has a thickness of 100-200 Å and an areal density of 0.5-0.7 g/cm ³ . If the electrode sheet is too thick, it will affect the rate performance of the material. If the electrode sheet is too thin, the energy density of the final overall device will be lowered. The density of the graphene electrode sheet is too small, which affects the volume energy density of the supercapacitor, which is not conducive to the use of the vehicle energy storage power source in rail transit. The graphene electrode sheet of the invention has a moderate thickness and a high density, and can ensure a high volume energy density of the device.

[0008] Preferably, the graphene electrode sheet has a thickness of 140-180 Å and an areal density of 0.55-0.65 g/cm ³

[0009] In the above low internal resistance, high power graphene supercapacitor electrode sheet, the graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , and a pore diameter of 2-10 nm, particle size 7-10 |im, the carbon content is greater than 99.8%, the oxygen-containing functional group content is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm. The physical properties of graphene directly affect the final performance of the device. The graphene material has a moderate pore size and a higher specific surface area, which is more conducive to improving the energy storage capacity of the material. However, the specific surface area and density of graphene are related to each other. The higher the specific surface area, the lower the density, which makes the pole piece difficult to process and the energy density low. Based on this, the specific surface area of the graphene material should not be too large, and the density is moderate. The pore size needs to be dominated by the mesopores, matching the size of the ions in the electrolyte. If the pore size is too small, the specific surface area utilization is low, the stored energy is low, and the rate performance is affected. Secondly, the excessive or too small particles of the graphene material are not conducive to the film formation of the graphene electrode. The excessive particle size affects the utilization rate of the material and the rate of B, and is easy to form stress concentration, which is not conducive to film formation; , more adhesive needs to be added, the contact resistance is increased, and the performance of the composite electrode is lowered. Thirdly, the higher the functional group content and the metal impurity content on the surface of the graphene material, the higher the potential, the easier the electrolyte decomposition is induced, and the capacity is decreased and the internal resistance is increased. Therefore, the present invention controls the basic physical property parameters of the graphene material within the above range.

[0010] In the above low internal resistance, high power graphene supercapacitor electrode sheet, the coated aluminum foil is formed by coating a conductive carbon material on an aluminum foil current collector, that is, having a conductive carbon layer on the aluminum foil.

[0011] The current collector does not play the role of energy storage in the electrode. Under the premise of ensuring the mechanical properties of the electrode sheet and the current carrying capacity of the current collector, the thickness of the current collector should be reduced as much as possible. The thickness of the corrosion aluminum foil in industrial applications is generally Maintained at 2 (Vm or more. In the above low internal resistance, high power graphene supercapacitor electrode sheet, the thickness of the coated aluminum foil is 10-20 1. In the coated aluminum foil, the conductive coating also does not exert energy storage. The thinner the coating, the thinner the better. According to the current state of the art, the thickness of the coated conductive carbon material is controlled at 100 nm-2 _[ xm.

[0012] Preferably, the coated aluminum foil has a thickness of 12-16 mm and a coating thickness of 500 nm to 1 pm.

[0013] In the above low internal resistance, high power graphene supercapacitor electrode sheet, the conductive agent is one or more of conductive carbon black, nano carbon fiber, carbon nanotube, and graphene conductive agent.

[0014] Preferably, the conductive agent is a composite conductive agent, which is a carbon black, carbon nanotube and graphene three-phase composite conductive agent. The zero-dimensional carbon black is contacted by "dot-point", the one-dimensional conductive agent is contacted by "line-line", and the two-dimensional graphene conductive agent constructs a three-dimensional conductive path through "face-to-face" contact. The composite conductive agent of different dimensions will produce a synergistic effect, and the conductive path can be easily constructed by the "point-line-surface" contact method, and the amount of the conductive agent added in the electrode can be reduced. [0015] According to the theoretical model calculation, when the mass ratio of the three-phase conductive agent in the composite conductive agent is close, the three-phase conductive agent will form a better synergistic effect, and preferably, the carbon black and the carbon nanotube in the composite conductive agent of the present invention The mass ratio of graphene is controlled in the range of 1: (0.8-1.2) : (0.8-1.2).

[0016] In the above low internal resistance, high power graphene supercapacitor electrode sheet, the binder is polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxy One or more of sodium methylcellulose (C MC), polyvinylpyrrolidone (PVP), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), natural cellulose.

Preferably, the binder is PTFE. Since PTFE has a good linear deformation mode, PTFE is preferably used as a good binder in the dry preparation of the graphene electrode sheet of the present invention.

Another object of the present invention is to provide a method for preparing the above low internal resistance, high power graphene supercapacitor electrode sheet, the preparation method comprising the following steps:

[0019] The graphene, the conductive agent and the binder are pre-mixed by mass percentage (75-93) : (2-10) : (5-15), and sheared, and then the obtained dry mixture is sequentially subjected to vertical Rolling and horizontal rolling to obtain a graphite carbon film;

[0020] The graphene carbon film and the current collector are pasted together by a conductive paste, and cured by heating to obtain a graphene supercapacitor electrode sheet.

[0021] In the preparation process of the wet electrode, it is necessary to adjust the viscosity of the slurry by means of a solvent (deionized water, etc.), and the capacitor is very sensitive to moisture in the subsequent preparation process, and it is difficult to remove the water even under high temperature and high vacuum drying treatment. Remove. The presence of moisture not only causes the electrode to be easily peeled off, but also causes an increase in leakage current of the product, which affects the stability of the product. In addition, the electrode density obtained by the wet electrode preparation process is low, and finally the monomer capacity and withstand voltage (less than 2.7 V) are limited. The application adopts the above dry electrode process to ensure the whole process of the waterless process in the preparation of the electrode, avoids the introduction of moisture which restricts the voltage increase, and improves the withstand voltage value of the monomer; at the same time, the dry electrode process can greatly increase the electrode by two-step rolling The density of the sheet effectively increases the quality of the active material per unit volume of the electrode, greatly increasing the capacity of the monomer.

[0022] The conductive adhesive of the present invention is a common conductive adhesive in the prior art, and the thickness of the conductive adhesive is controlled at 1~2 pm.

[0023] In the above method for preparing a low internal resistance, high power graphene supercapacitor electrode sheet, the vertical rolling and horizontal rolling pressures are both 100-300 MPa. The magnitude of the pressure in the present invention affects the final graphene carbon film Thickness, density and compactness. If the pressure is too small, the carbon film has a large gap, a low density, and a thick piece; the opposite pressure is too large, and the carbon film wrinkles or even cracks.

[0024] Preferably, the pressure of the rolling (the pressure of vertical rolling and horizontal rolling) is 120-250 MPa.

Still more preferably, the rolling pressure is 150 MPa.

[0025] In the above method for preparing a low internal resistance, high power graphene supercapacitor electrode sheet, the heat curing temperature is 100-200 ° C, and the heat curing time is 10-30 min.

Advantageous effects of the invention

Beneficial effect

Compared with the prior art, the present invention selects a suitable graphene material as the main energy storage material of the super capacitor. Graphene has an ultra-high specific surface area and excellent electrical conductivity, and is considered to be a low internal resistance. High power supercapacitor energy storage materials. In view of the low density of the graphene material and the difficulty in processing the pole piece, the present invention adopts a dry electrode processing process and applies a novel ultra-thin coated aluminum foil. The coated aluminum foil has a rough surface that ensures good adhesion between the graphene carbon film and the current collector. Compared to corroded aluminum foil, coated aluminum foil has better electrical conductivity, and the application of coated aluminum foil can reduce the internal resistance of the graphene electrode sheet. In addition, coated aluminum foil has better mechanical properties and flexibility. Under the premise of ensuring processability, the coated aluminum foil can be thinner, which can reduce the quality of the current collector and increase the specific energy of the device.

[0027] Secondly, the invention adopts a carbon black/carbon nanotube/graphene three-phase composite conductive agent, fully utilizes the synergistic effect between the conductive agents of different geometric structures, and constructs a three-dimensional conductive network through a “point-line-surface” contact method. , reduce the internal resistance of the pole piece and increase the power density of the device.

Therefore, the supercapacitor graphene electrode sheet of the present invention has characteristics such as low internal resistance, high power, and the like.

Brief description of the drawing

DRAWINGS

1 is a scanning electron micrograph of a graphene material according to Embodiment 1 of the present invention.

2 is a schematic view of an electrode sheet according to Embodiment 1 of the present invention.

3 is an accelerated life curve of a current collector capacity of a coated aluminum foil and a corroded aluminum foil according to Embodiment 1 of the present invention.

4 is an accelerated life curve of an internal resistance of a coated aluminum foil and a corroded aluminum foil current collector according to Embodiment 1 of the present invention.

Invention embodiment Embodiments of the invention

The following is a description of the specific embodiments of the present invention with reference to the accompanying drawings, and the present invention is not limited to these embodiments.

Embodiment 1

[0035] The graphene, the conductive agent and the binder are uniformly mixed in advance by a mass percentage of 88:6:6, and the mixture obtained above is subjected to over-speed shear mixing at a shear rate of 10,000 rpm, and then under a pressure of 150 MPa. The dry mixture is sequentially subjected to "vertical" and "horizontal" two-step rolling to obtain a graphene carbon film having a uniform thickness. The graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , a pore diameter of 2-10 nm, a particle size of 7-10 |im, and a carbon content of more than 99.8%. The content of the oxygen-containing functional group is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm, and the microscopic morphology thereof is shown in FIG. The conductive agent is a three-phase composite conductive agent of conductive carbon black, carbon nanotubes and graphene, and the mass ratio of the three is 1: 1:1. The composite conductive agent powder is obtained by dispersing and mixing by liquid phase grinding and freeze-drying. The binder is PTFE.

[0036] The graphene carbon film prepared above and the coated aluminum foil current collector are pasted together by a conductive adhesive, wherein the thickness of the conductive adhesive is controlled to be about 1.5 | im, and after curing at 160 ° C for 20 minutes, A graphene electrode sheet is obtained. The coated aluminum foil has a thickness of 14 pm, wherein the thickness of the coating is lpm. The graphene electrode sheet has a thickness of 15 (Hon, an areal density of 0.66 g/cm ³ , and an electronic photograph as shown in FIG. 2 .

[0037] The graphene electrode sheet is sequentially subjected to slitting, winding, assembly, drying, liquid injection, and packaging processes to prepare a wound graphene supercapacitor. The measured monomer capacity is 3600F and the internal resistance is 0.12 mQ. The coated aluminum foil current collector supercapacitor and corroded aluminum foil current collector supercapacitor at 65 ° C - 2.85 V specific capacity and DC internal resistance accelerated life curve shown in Figure 3, 4. As can be seen from the figure, during the accelerated life test, the capacity retention rate of the coated aluminum foil supercapacitor is higher than that of the corroded aluminum foil supercapacitor, and the internal resistance increases less than that of the corroded aluminum foil supercapacitor.

Embodiment 2

[0039] The graphene, the conductive agent, and the binder are uniformly mixed in advance by 90:4:6 by mass, and the mixture obtained above is subjected to over-speed shear mixing at a shear rate of 11,000 rpm, and then under a pressure of 200 MPa. The dry mixture is sequentially subjected to "vertical" and "horizontal" two-step rolling to obtain a graphene carbon film having a uniform thickness. The graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , and an aperture 2-10 nm, particle size 7-10

|im, the carbon content is greater than 99.8%, the oxygen-containing functional group content is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm. The conductive agent is a three-phase composite conductive agent of conductive carbon black, carbon nanotubes and graphene, and the mass ratio of the three is 1:1.1:0.9. The composite conductive agent powder is obtained by dispersing and mixing by liquid phase grinding and freeze-drying. The binder is polyvinylidene fluoride (PVDF).

[0040] The above-prepared graphene carbon film coating is formed by an aluminum foil current collector with a conductive glue, which control the thickness of the conductive paste is about 1.2 _{| i} m, heat curing at 180 ° C 12 minutes after A graphene electrode sheet can be obtained. The coated aluminum foil has a thickness of 12 pm and a coating thickness of 600 nm. The graphene electrode sheet had a thickness of 140 [xm and an areal density of 0.63 g/cm ³ .

[0041] The graphene electrode sheet is sequentially subjected to slitting, winding, assembly, drying, liquid injection, and packaging processes to prepare a wound graphene supercapacitor. The measured monomer capacity is 3500F and the internal resistance is 0.13 mQ.

Embodiment 3

[0043] The graphene, the conductive agent, and the binder are uniformly mixed in advance by 85:8:7 by mass, and the mixture obtained above is subjected to over-speed shear mixing at a shear rate of 9000 rpm, and then under a pressure of 250 MPa. The dry mixture is sequentially subjected to "vertical" and "horizontal" two-step rolling to obtain a graphene carbon film having a uniform thickness. The graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , a pore diameter of 2-10 nm, a particle size of 7-10 |im, and a carbon content of more than 99.8%. The content of the oxygen-containing functional group is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm. The conductive agent is a three-phase composite conductive agent of conductive carbon black, carbon nanotubes and graphene, and the mass ratio of the three is 1 _: 0.9: 1.1. The composite conductive agent powder is obtained by dispersing and mixing by liquid phase grinding and freeze-drying. The binder is styrene butadiene rubber (SBR).

[0044] The graphene carbon film prepared above and the coated aluminum foil current collector are pasted together by a conductive adhesive, wherein the thickness of the conductive adhesive is controlled to be about 1.8 | im, and after curing at 140 ° C for 28 minutes, A graphene electrode sheet is obtained. The coated aluminum foil has a thickness of 16 pm and a coating thickness of 1 pm. The graphene electrode sheet has a thickness of 160

_[ xm, areal density 0.62 g/cm ³ _°

[0045] The graphene electrode sheet is sequentially subjected to slitting, winding, assembly, drying, liquid injection, and packaging processes to prepare a wound graphene supercapacitor. The tested monomer capacity was 3410F and the internal resistance was 0.14 mQ.

Example 4 [0047] The graphene, the conductive agent and the binder are uniformly mixed in advance by a mass percentage of 78:8:14, and the mixture obtained above is subjected to over-speed shear mixing at a shear rate of 11,000 rpm, and then under a pressure of 220 MPa. The dry mixture is sequentially subjected to "vertical" and "horizontal" two-step rolling to obtain a graphene carbon film having a uniform thickness. The graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , a pore diameter of 2-10 nm, and a particle size of 7-10.

|im, the carbon content is greater than 99.8%, the oxygen-containing functional group content is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm. The conductive agent is a composite conductive agent composed of conductive carbon black and carbon nanotubes in a mass ratio of 1:1. The composite conductive agent powder is obtained by dispersing and mixing by liquid phase grinding and freeze-drying. The binder is sodium carboxymethyl cellulose (CMC).

[0048] The graphene carbon film prepared above and the coated aluminum foil current collector are pasted together by a conductive adhesive, wherein the thickness of the conductive adhesive is controlled to be about 1.6 | im, and after curing at 120 ° C for 25 minutes, A graphene electrode sheet is obtained. The coated aluminum foil had a thickness of 18 pm and a coating thickness of 600 nm. The graphene electrode sheet has a thickness of 120

_[ xm, surface density is 0.58 g/cm ³ .

[0049] A graphene electrode sheet is sequentially subjected to slitting, winding, assembly, drying, liquid injection, and packaging processes to prepare a wound graphene supercapacitor. The measured monomer capacity is 3350F and the internal resistance is 0.15 mQ.

[0050] Example 5

[0051] The graphene, the conductive agent, and the binder are uniformly mixed in advance by 93:2:5 by mass, and the mixture obtained above is subjected to over-speed shear mixing at a shear rate of 12,000 rpm, and then under a pressure of 100 MPa. The dry mixture is sequentially subjected to "vertical" and "horizontal" two-step rolling to obtain a graphene carbon film having a uniform thickness. The graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , a pore diameter of 2-10 nm, a particle size of 7-10 |im, and a carbon content of more than 99.8%. The content of the oxygen-containing functional group is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm. The conductive agent is a three-phase composite conductive agent of conductive carbon black, carbon nanotubes and graphene, and the mass ratio of the three is 1:1.1:0.9. The composite conductive agent powder is obtained by dispersing and mixing by liquid phase grinding and freeze-drying. The binder is polyvinylpyrrolidone (PVP).

[0052] The graphene carbon film prepared above and the coated aluminum foil current collector are pasted together by a conductive adhesive, wherein the thickness of the conductive adhesive is controlled to be about 2 | im, and after curing at 100 ° C for 30 minutes, A graphene electrode sheet is obtained. The coated aluminum foil has a thickness of 1 (Vm, a coating thickness of 100 nm. The graphene electrode sheet has a thickness of 100, a surface The density was 0.56 g/cm ³ .

[0053] The graphene electrode sheet is sequentially subjected to slitting, winding, assembly, drying, liquid injection, and packaging processes to prepare a wound graphene supercapacitor. The monomer capacity was 3280F and the internal resistance was 0.11 mQ.

Example 6

[0055] The graphene, the conductive agent, and the binder are uniformly mixed in advance by 75:10:15 by mass, and the mixture obtained above is subjected to over-speed shear mixing at a shear rate of 8000 rpm, and then under a pressure of 300 MPa. The dry mixture is sequentially subjected to "vertical" and "horizontal" two-step rolling to obtain a graphene carbon film having a uniform thickness. The graphene has a specific surface area of 1000-1500 m ² /g, a tap density of 0.2-0.5 g/cm ³ , a pore diameter of 2-10 nm, and a particle size of 7-10.

|im, the carbon content is greater than 99.8%, the oxygen-containing functional group content is less than 0.35 meq/g, the water content is less than 0.40%, and the total metal content is less than 100 ppm. The conductive agent is a nano carbon fiber. The composite conductive agent powder is obtained by dispersing and mixing by liquid phase grinding and freeze-drying. The binder is polyvinylidene fluoride-hexafluoropropylene (PVDF-H FP).

[0056] The graphene carbon film prepared above and the coated aluminum foil current collector are pasted together by a conductive adhesive, wherein the thickness of the conductive adhesive is controlled to be about 1 | om, and after heating and curing at 200 ° C for 10 minutes, A graphene electrode sheet is obtained. The coated aluminum foil has a thickness of 2 (Vm, a coating thickness of 2 pm. The graphene electrode sheet has a thickness of 20 (Hon, an areal density of 0.54 g/cm ³ _°).

[0057] The graphene electrode sheet is sequentially subjected to slitting, winding, assembly, drying, liquid injection, and packaging processes to prepare a wound graphene supercapacitor. The monomer capacity was 3300F and the internal resistance was 0.16 mQ.

Example 7

[0059] The only difference from Embodiment 1 is that the graphene in the embodiment 7 has a specific surface area of 700 to 1000 m ² /g and a tap density of 0.3 to 0.5 g/cm ³ . The measured monomer capacity is 3000F, and the internal resistance is 0.12 mQ.

Example 8

[0061] The difference from Embodiment 1 is only that the conductive agent in the embodiment 8 is a mass ratio of carbon nanotubes to graphene.

1: 1 consists of a conductive agent to make a supercapacitor. The measured monomer capacity is 3400F and the internal resistance is 0.13 mQ.

Example 9

[0063] The only difference from Embodiment 1 is that the coated aluminum foil in the embodiment 9 has a thickness of 25 pm and a coating thickness of 2.

5pm, made a super capacitor. The monomer capacity was 3180F and the internal resistance was 0.16 mQ. Comparative Example 1

[0065] The only difference from the embodiment 1 is that the current collector in the comparative example 1 is a corroded aluminum foil having a thickness of 20 Å, which is not described herein in other steps. Detected monomer capacity 3220F, internal resistance 0.19

mQ. The accelerated life curves of specific capacity and DC internal resistance at 65 °C - 2.85 V are shown in Figures 3 and 4.

[0066] The initial internal resistance of the supercapacitor of the coated aluminum foil is significantly lower than that of the corroded aluminum foil, and the initial capacity is also about 10% higher.

As can be seen from the comparison, coated aluminum foil is a better choice for long-life, low internal resistance, high-power supercapacitor current collectors.

[0067] In addition, the new technical solutions formed by the unrestricted point values in the technical scope of the claimed invention and the equivalent replacement of single or multiple technical features in the technical solutions of the embodiments are also required by the present invention. Within the scope of the protection; at the same time, in all of the enumerated or unexemplified embodiments of the present invention, the respective parameters in the same embodiment merely represent one example of the technical solution (ie, a feasible solution).

[0068] The specific embodiments described herein are merely illustrative of the spirit of the invention. A person skilled in the art can make various modifications or additions to the specific embodiments described, or in a similar manner, without departing from the spirit of the invention or beyond the scope of the appended claims.

[0069] While the invention has been described in detail and shown in the embodiments of the invention

Claims

Claim

[Claim 1] A low internal resistance, high power graphene supercapacitor electrode sheet, wherein the graphite dilute electrode sheet comprises a current collector and a graphite dilute electrode slurry, wherein the graphite dilute electrode paste comprises mass percentages respectively It is 75-93% graphene, 2-10% conductive agent, 5-15% binder, and the current collector is coated aluminum foil.

[Claim 2] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 1, wherein the graphene electrode sheet has a thickness of 100-200- and an areal density of 0.5-0.7 g. /cm ³ .

[Claim 3] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 2, wherein the graphene electrode sheet has a thickness of 140-180

[xm, areal density is 0.55-0.65 g/cm ³ .

[Claim 4] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 1, wherein the graphene has a specific surface area of 1000-1500 m ²

/g , tap density is 0.2-0.5 g/cm ³ , pore size is 2-10 nm, particle size is 7-10 _|i m , carbon content is greater than 99.8%, oxygen-containing functional group content is less than 0.35 meq/g, water content Less than 0.4 0%, the total metal content is less than 100 ppm.

[Claim 5] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 1, wherein the coated aluminum foil is formed by coating a conductive carbon material on an aluminum foil current collector.

[Claim 6] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 5, wherein the coated aluminum foil has a thickness of 10-20

The coating thickness is 100 nm - 2 pm.

[Claim 7] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 6, wherein the coated aluminum foil has a thickness of 12-16 pm and a coating thickness of 500 nm-l^ Im

[Claim 8] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 1, wherein the conductive agent is conductive carbon black, nano carbon fiber, carbon nanotube, graphene conductive agent One or several of them.

[Claim 9] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 8, wherein the conductive agent is a composite conductive agent, which is carbon black, carbon nanotubes and graphene. Three-phase composite conductive agent.

[Claim 10] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 9, wherein the mass ratio of carbon black, carbon nanotubes, and graphite is 1: (0.8-1.2): (0.

8-1.2).

[Claim 11] The low internal resistance, high power graphene supercapacitor electrode sheet according to claim 1, wherein the binder is polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PT) FE), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), one or more of natural cellulose .

[Claim 12] A method for preparing a low internal resistance, high power graphene supercapacitor electrode sheet according to claim 1, wherein the preparation method comprises the following steps:

Graphene, conductive agent and adhesive by mass percentage (75-93) : (2-10) :

(5-15) pre-mixing, and shearing, and then the obtained dry mixture is sequentially subjected to vertical rolling and horizontal rolling to obtain a graphene carbon film;

The graphene carbon film and the current collector are pasted together by a conductive paste, and are heated and solidified to obtain a graphene super capacitor electrode sheet.

[Claim 13] The method for preparing a low internal resistance, high power graphene supercapacitor electrode sheet according to claim 12, wherein the thickness of the conductive paste is controlled

[Claim 14] The method for preparing a low internal resistance, high power graphene supercapacitor electrode sheet according to claim 12, wherein the vertical rolling and the horizontal rolling pressure are both 100-300 MPa

[Claim 15] The method for preparing a low internal resistance, high power graphene supercapacitor electrode sheet according to claim 12, wherein the heat curing temperature is 100-200 ° C, and the heat curing time is 10- 30 min.