CN104538203B - A kind of transparent ultracapacitor and preparation method thereof - Google Patents

Abstract

The invention discloses a transparent supercapacitor and a preparation method thereof. Specifically, two transparent carbon nanotube film electrodes are loaded side by side on a transparent substrate, and the surface is coated with a transparent gel electrolyte. The two transparent electrodes of the supercapacitor are located in the same plane, which is different from the traditional sandwich sandwich structure. The supercapacitor with a single-layer electrode structure shortens the light propagation path and allows light to efficiently pass through the capacitor device, thereby realizing a highly transparent supercapacitor. The light transmittance of the electrode part of the supercapacitor prepared by the invention is as high as 75%, and the light transmittance in the visible light range reaches 70-80%. The supercapacitor also has excellent capacitor characteristics and electrochemical performance. The transparent supercapacitor prepared by the invention has important application prospects in the fields of display, touch screen, photoelectric conversion and energy storage. At the same time, the preparation method of the transparent supercapacitor provided by the invention has a simple process, is easy to implement, and can be produced in a large scale and industrialized.

Description

A kind of transparent supercapacitor and preparation method thereof

technical field

The invention discloses a transparent supercapacitor and a preparation method thereof, and specifically belongs to the technical field of supercapacitors.

Background technique

Supercapacitors are one of the most widely used energy storage devices due to their high specific capacity, high power density and long cycle life. The development of portable, integrated and intelligent electronic devices today puts forward new requirements for supercapacitors as basic energy storage units. Especially in the field of transparent integrated electronics, such as displays, touch screens, e-books, photoelectric energy conversion and energy storage systems, supercapacitors are not only required to have high electrochemical performance, but also require high transparency to be compatible with other devices The structural performance requirements of the unit.

Traditional supercapacitors have a sandwich sandwich structure, which is composed of two layers of electrodes filled with electrolyte. The supercapacitor with this structure contains multiple unit layers, and the transparency of each unit layer will affect the overall light transmittance of the capacitor device. In addition, the electrode materials currently used are basically films made of carbon materials, metals, metal oxides, conductive polymers or their mixtures. These film electrodes are basically opaque, and the assembly of two layers of film electrodes into a sandwich structure will inevitably reduce the overall cost. Transparency of capacitive devices. Patent 201210579735.5 discloses a transparent and flexible electrochemical device based on a planar comb-shaped electrode structure and its preparation method. The main step is to etch a pair of Intersecting comb-shaped patterns, and then use the electron beam evaporation method to coat a layer of nickel metal film on the corresponding comb patterns, protect the gaps between the comb patterns with water-proof glue, and dip the ink on the nickel surface for many times Deposit a layer of carbon nanoparticle film, cover the surface with a layer of PET, seal the edges of the upper and lower layers of PET, and finally inject the propylene carbonate solution of tetraethylammonium tetrafluoroborate in the liquid phase as the electrolyte between the two PETs. A supercapacitor with two comb-shaped carbon nanoparticle films as two electrodes and a bottom nickel film as a current collector is obtained. Although the two carbon nanoparticle film electrodes of the capacitor are on the same substrate, the carbon nanoparticle film electrodes themselves are opaque to light, and only the gap between the two electrodes is used to transmit light, so a real transparent supercapacitor has not been realized. In addition, liquid electrolyte requires at least two layers of shells to be packaged into a capacitor. The incident light must pass through the electrode, electrolyte, and upper and lower shell layers to penetrate the entire device. This multi-layer structure is not conducive to obtaining a highly transparent capacitor device. The light transmittance of the gap part of the capacitor prepared by the above method is only 42%, and the electrode part is opaque.

Limited by traditional structures and electrode materials, the light transmittance of currently reported supercapacitors is very limited, and the light transmittance is basically below 50%, which is far from meeting the requirements of practical applications. Therefore, it is necessary to develop highly transparent supercapacitors.

Contents of the invention

Based on the technical development requirements of integration and intelligent electronics, the present invention provides a transparent supercapacitor and a preparation method thereof in view of the limitation of low light transmittance of the existing traditional structure supercapacitor.

A transparent supercapacitor provided by the present invention is specifically composed of two transparent carbon nanotube film electrodes loaded side by side on a transparent substrate, and the surface is coated with a transparent gel electrolyte, wherein the two transparent carbon nanotube film electrodes maintain a certain distance; as shown in Figure 1 Show.

In the present invention, the transparent supercapacitor is characterized in that it has a single-layer transparent electrode structure, and two transparent carbon nanotube film electrodes are parallel and arranged on the same plane. This structure has only one layer of electrodes, which is different from the traditional sandwich sandwich structure in the past. Therefore, light only needs to pass through a single layer of electrode film, which greatly shortens the light transmission distance and is conducive to obtaining high-transparency capacitor devices. Combined with transparent carbon nanotube film electrodes, light can pass through the electrodes more efficiently, thereby obtaining high transparent capacitance devices.

In the present invention, the distance between the electrodes of the two carbon nanotube films of the transparent supercapacitor is 100 μm-3 mm.

In the present invention, the electrode of the transparent supercapacitor is a transparent carbon nanotube film material, and the carbon nanotube film is connected to a network by one-dimensional carbon nanotubes, and has high light transmittance.

In the present invention, the light transmittance of the transparent carbon nanotube film is above 50%, preferably above 70%.

In the present invention, the transparent carbon nanotube film has a nanometer or micrometer scale thickness, preferably 5-500nm.

In the present invention, the carbon nanotube coverage of the transparent carbon nanotube film is between 10% and 90%.

In the present invention, the pore size of the transparent carbon nanotube film is between 5 nm and 5 μm.

In the present invention, the transparent carbon nanotube film can be prepared by array method, solution method or vapor phase deposition method.

In the present invention, the transparent carbon nanotube film is prepared by chemical vapor deposition.

In the present invention, the transparent substrate is a transparent rubber, plastic, glass film or sheet.

In the present invention, the current collector is metal foil, metal wire or metal film.

In the present invention, the conductive material is conductive silver paste and conductive glue.

In the present invention, the transparent gel electrolyte is sulfuric acid/polyvinyl alcohol/water, phosphoric acid/polyvinyl alcohol/water.

A kind of preparation method of transparent supercapacitor provided by the invention comprises the following steps:

(1) First, the transparent carbon nanotube film is loaded on the transparent substrate by the film transfer method or physical deposition method, and then the carbon nanotube film is divided into two electrodes, and the two electrodes are kept at a certain distance; or: by film transfer or physical deposition method, Load two transparent carbon nanotube film electrodes directly on the transparent substrate, and keep a certain distance between the two electrodes;

(2) Connect one end of the two electrodes to the current collector with a conductive material;

(3) A layer of transparent gel electrolyte is evenly coated on the surface of the two electrodes and between the two electrodes to prepare a transparent supercapacitor.

The supercapacitor prepared by the invention has high light transmittance. A transparent supercapacitor was fabricated using transparent carbon nanotube films as electrodes. Under the visible wavelength of 550nm of the prepared supercapacitor, the light transmittance at the electrode part of the supercapacitor reaches more than 75%, and the light transmittance in the entire visible light range reaches 70-80%. The gap between the electrodes of the supercapacitor is basically completely transparent.

The supercapacitor prepared by the invention can further improve the light transmittance of the supercapacitor by optimizing the carbon nanotube structure, pore size and carbon nanotube film thickness in the carbon nanotube film.

The transparent supercapacitor prepared by the invention has good electrochemical performance. The supercapacitor shows good capacitor characteristics and high specific capacitance, and the specific capacitance reaches 69.5F/g.

The transparent supercapacitor prepared by the invention can be applied in the field of transparent electronic devices, especially displays requiring high transparency, touch screens, electronic books, photoelectric energy conversion and energy storage systems, and has important application prospects.

The method for preparing a transparent supercapacitor provided by the invention has a simple process and is easy to implement, and the single-layer electrode structure can also develop an ultrathin and superlarge transparent supercapacitor, which can realize large-scale production and application.

Compared with the existing supercapacitor and preparation technology, the present invention has the following benefits and technical effects:

1. Adopt a single-layer electrode structure, reduce the light propagation path, make the light pass through more effectively, and realize a high transparent capacitor device;

2. Using a single-layer electrode structure, it can also realize ultra-thin supercapacitors;

3. Using a single-layer electrode structure, it can also realize a super capacitor with a large area;

4. Using a single-layer symmetrical electrode structure, it is more convenient to realize the series and parallel connection of electrodes or the entire supercapacitor;

5. Using transparent carbon nanotube film as the electrode, using the high conductivity and high specific surface area of the carbon nanotube film, the supercapacitor prepared achieves high transparency and high electrochemical performance;

6. The preparation method of the transparent supercapacitor provided by the present invention has a simple process, is easy to control, is easy to realize, and can be produced and applied on a large scale.

Description of drawings

Figure 1: Schematic diagram of the structure of the transparent supercapacitor provided by the present invention.

Figure 2: Photo of the transparent carbon nanotube film electrode material used in the preparation of the transparent supercapacitor according to the present invention.

Figure 3: Scanning electron micrograph of the transparent carbon nanotube film electrode material used in the preparation of the transparent supercapacitor according to the present invention.

Figure 4: Photo of a transparent supercapacitor prepared by Example 1 of the present invention.

Figure 5: UV-Vis absorption spectrum of the transparent supercapacitor prepared by Example 1 of the present invention.

Figure 6: The cyclic voltammetry curve of the transparent supercapacitor prepared by Example 1 of the present invention, with a scan rate of 100 mV/s.

Figure 7: The constant current charge and discharge curve of the transparent supercapacitor prepared by Example 1 of the present invention, the current density is 0.1A/g.

detailed description

Example 1

The aluminum foil-supported carbon nanotube film prepared by chemical vapor deposition was used as the electrode. The light transmittance of the carbon nanotube film is 75%. Figure 2 is a photo of the transparent carbon nanotube film electrode material used in the present invention, showing high transparency. The thickness of the carbon nanotube film is 100nm, the coverage rate of the carbon nanotubes in the film is about 30%, and the pore size of the pores between the carbon nanotubes is 5nm-5μm. Fig. 3 is a scanning electron micrograph of the transparent carbon nanotube film used in the present invention. Using polydimethylsiloxane (PDMS) as a transparent matrix, specifically mix rubber liquid and curing agent (Sylgard 184, Dow Corning Company) at a mass ratio of 10:1, and pour a certain mass into a plastic mold to make the mixed liquid self-leveling , evacuated for 2 hours to remove air bubbles, left at room temperature to cure for 48 hours, and obtained a PDMS transparent sheet with a thickness of 1 mm. Use a razor blade to cut the PDMS sheet into rectangular pieces of suitable size as a transparent substrate. Using sulfuric acid/polyvinyl alcohol/water as the gel electrolyte, add 5g concentrated sulfuric acid (98%) to 50g deionized water and mix evenly, then add 5g polyvinyl alcohol powder (PVA, Aldrich, molecular weight 140000-180000), 700- Stir vigorously at 1000rpm and heat to 85-90°C for ~4h until the mixture becomes viscous liquid.

Transfer the carbon nanotube film from the aluminum foil to the transparent PDMS substrate, cut the carbon nanotube film along a straight line from the middle of the carbon nanotube film with a wooden toothpick, and divide the carbon nanotube film into two symmetrical rectangular films as two electrodes with a distance of 1 mm between the two electrodes. Connect one end of the two electrodes to the copper foil as a current collector with conductive silver paste. A layer of gel electrolyte is evenly coated on the surface and between the electrodes of the two carbon nanotube membranes, and left to stand at room temperature for 24 hours to cure, thereby preparing a highly transparent supercapacitor. The gel electrolyte layer is 50 μm thick. Fig. 4 is a transparent supercapacitor prepared by the above method and steps.

Electrode films and transparent supercapacitor structures were characterized by light microscopy (U-25LBD, OLYMPUS, Japan) and scanning electron microscopy (S-4800, Hatchi, Japan). The light transmittance of electrode film and supercapacitor was tested by UV-Vis spectrophotometer (UV-2700, Shimadzu, Japan). The electrochemical performance of the capacitors was tested by an electrochemical workstation (CHI660C, Chenhua, Shanghai, China).

The supercapacitors prepared by the above steps have high transparency. At a visible wavelength of 550nm, the light transmittance of the electrodes of the supercapacitor reaches more than 75%, and the light transmittance in the entire visible light range reaches 70-80% (Figure 5). The gap between the electrodes of the supercapacitor is almost completely transparent. The transparent supercapacitor also has excellent electrochemical performance. The supercapacitor prepared with the carbon nanotube film as the electrode has good capacitor characteristics (Figure 6 and Figure 7), and the specific capacitance reaches 69.5F/g at a current density of 1A/g.

Example 2

The experimental method and process are the same as in Example 1, except that an unsupported carbon nanotube film prepared by chemical vapor deposition is used as an electrode. The thickness of the carbon nanotube film is 100nm, the coverage rate of the carbon nanotube is 30%, the size of the pores between the carbon nanotubes is 5nm-5μm, and the light transmittance of the carbon nanotube film is 75%. Spread the carbon nanotube film on the transparent PDMS substrate, cut the carbon nanotube film from the middle of the carbon nanotube film along the corrugated curve with a wooden toothpick, divide the carbon nanotube film into two symmetrical rectangular films as two electrodes, and the distance between the two electrodes is 1mm. Connect one end of the two electrodes to the copper foil as a current collector with conductive silver paste. A layer of gel electrolyte is evenly coated on the surface and between the electrodes of the two carbon nanotube membranes, and left to stand at room temperature for 24 hours to cure, thereby preparing a highly transparent supercapacitor. The gel electrolyte layer is 50 μm thick.

Example 3

The carbon nanotube film, transparent substrate and gel electrolyte are the same as in Example 1, except that the carbon nanotube film is first thinned and then processed into an electrode, specifically: the carbon nanotube film is transferred from the aluminum foil to the transparent PDMS substrate, Spread another PDMS sheet of the same size on the surface of the carbon nanotube membrane, lightly press the upper PDMS sheet, and gently separate the two PDMS sheets from one section to obtain two evenly layered carbon nanotube membranes loaded with PDMS. The layered carbon nanotube film is used as an electrode, the thickness is 50nm, the coverage rate of the carbon nanotube film is about 15%, and the light transmittance of the carbon nanotube film supported by PDMS is 81%. Dip the carbon nanotube film along a straight line from the middle of the carbon nanotube film after dipping in the ethanol solution with a metal needle tip, divide the carbon nanotube film into two symmetrical rectangular films as two electrodes, and the distance between the two electrodes is 100 μm. Connect one end of the two electrodes to the copper foil as a current collector with conductive silver paste. A thin layer of gel electrolyte is evenly coated on the surface and between the electrodes of the two carbon nanotube membranes, and left to stand at room temperature for 12 hours to cure, thereby preparing a highly transparent supercapacitor. The gel electrolyte layer is 10 μm thick.

Example 4

The carbon nanotube film, transparent substrate and gel electrolyte are the same as in Example 1, except that the two-layered carbon nanotube film is used as the electrode, specifically: first transfer a layer of carbon nanotube film from the aluminum foil to the transparent PDMS substrate , Gently remove another layer of carbon nanotube film from the aluminum foil and spread it on the surface of the first layer of carbon nanotube film, drop ethanol on the surface of carbon nanotube to make the two layers of film tightly bonded and attached to the PDMS substrate, and obtain a PDMS-supported Two-layer stacked carbon nanotube film. The thickness of the two-layer stacked carbon nanotube film is about 200nm, the coverage rate of the carbon nanotube film is about 60%, and the light transmittance of the two-layer stacked carbon nanotube film supported by PDMS is 42%. Then according to the steps of Example 1, a translucent supercapacitor was prepared. The gel electrolyte layer is 100 μm thick.

Example 5

The carbon nanotube film, transparent matrix and gel electrolyte are the same as in Example 1, except that the four-layer laminated carbon nanotube film is used as an electrode, and the specific stacking method is the same as in Example 4. After each film is laid, it is dripped on the surface of the film. Ethanol makes the membranes tightly combined and attached to the PDMS substrate, and a four-layer carbon nanotube membrane supported by PDMS is obtained. The thickness of the four-layer stacked carbon nanotube film is about 400nm, the coverage rate of the carbon nanotube film is about 90%, and the light transmittance of the four-layer stacked carbon nanotube film supported by PDMS is 21%. Then according to the steps of Example 1, a supercapacitor with lower transparency was prepared. The gel electrolyte layer is 500 μm thick.

Example 6

A carbon nanotube film supported by a polyethylene terephthalate (PET) film directly prepared by a chemical vapor deposition method is directly used as a transparent electrode film. The light transmittance of the PET supported carbon nanotube film is 86.3%. The PET film is transparent, 60 μm thick, and has a low-viscosity surface, purchased from Haining Protective Film Co., Ltd. The gel electrolyte is the same as in Example 1. The electrode is processed and prepared by plasma etching, specifically: cover the two ends of the carbon nanotube film with a glass slide as a mask, leave a gap in the middle of the carbon nanotube film to expose to the air, the gap width is 1mm, and then use air plasma (Harrick Plasma, PDC-32G, USA) to etch the carbon nanotube film until the carbon nanotubes in the gap are completely etched away to obtain two carbon nanotube film electrodes with a distance of 1 mm between the two electrodes. The ends of the two electrodes were respectively connected to the copper wire with conductive glue as the current collector, and a layer of gel electrolyte was uniformly coated on the surface of the carbon nanotube film, and left at room temperature to cure for 24 hours, thereby preparing a transparent supercapacitor.

Example 7

The carbon nanotube film and gel electrolyte are the same as in Example 1. A glass sheet is used as a transparent substrate, specifically a laboratory glass slide, and two transparent carbon nanotube film electrodes are directly transferred to the transparent substrate. Specifically: gently remove a carbon nanotube film from the aluminum foil and spread it on the surface of the glass substrate, drop a drop of ethanol on the surface of the carbon nanotube film, so that the electrode of the carbon nanotube film is closely attached to the glass substrate under the wetting effect of ethanol In the same way, another carbon nanotube film electrode of the same size was flatly spread on the glass substrate, and the two electrodes were kept parallel and side by side with a distance of 3 mm. Connect one end of the two electrodes to the copper foil as a current collector with conductive silver paste. A layer of gel electrolyte is evenly coated on the surface and between the electrodes of the two carbon nanotube membranes, and left to stand at room temperature for 24 hours to cure, thereby preparing a highly transparent supercapacitor.

Example 8

The experimental method and process are the same as those in Embodiment 7, except that the transparent polyethylene (PE) film is used as the transparent substrate, and the PE film is transparent with a thickness of 10 μm. In addition, a gold film was directly deposited on both ends of the carbon nanotube film electrode as a current collector. A highly transparent supercapacitor is thus prepared.

Example 9

The experimental method and process are the same as those in Implementation 1, except that phosphoric acid/polyvinyl alcohol/water is used as the transparent gel electrolyte to prepare a transparent supercapacitor.

Claims (9)

1. A kind of 1. transparent ultracapacitor, it is characterized in that being carried on transparent base, table side by side by two transparent carbon nanotube membrane electrodes Face coating clear gel electrolyte is formed, wherein two transparent carbon nanotube membrane electrodes keep a determining deviation；The transparent super electricity Container preparation method comprises the following steps：

   (1) transparent carbon nanotube membrane is first carried on transparent base by film transfer method or physical deposition methods, then by CNT Film is divided into two electrodes, and two electrodes keep a determining deviation；Or：By film transfer or physical deposition methods, by two transparent carbon nanotubes Membrane electrode is directly carried on transparent base, and two electrodes keep a determining deviation；

   (2) two electrode one end are connected into collector with conductive material respectively；

   (3) layer of transparent gel electrolyte is uniformly coated between two electrode surfaces and two electrodes, transparent super capacitor is made Device；

   The light transmittance of described transparent carbon nanotube membrane electrode is in 50%-95%.
2. 2. transparent ultracapacitor according to claim 1, it is characterised in that its two transparent carbon nanotube membrane electrode positions In same plane, two 100 μm of electrode spacing -3mm.
3. 3. transparent ultracapacitor according to claim 1, it is characterised in that carbon is received in described transparent carbon nanotube membrane Mitron coverage rate is between 10%-90%, and the aperture size of hole is between 5nm-5 μm between CNT.
4. 4. transparent ultracapacitor according to claim 1, it is characterised in that described transparent carbon nanotube membrane electrode tool There are nanometer or micro-meter scale thickness.
5. 5. transparent ultracapacitor according to claim 4, it is characterised in that described transparent carbon nanotube membrane electrode is thick Spend 5-500nm.
6. 6. transparent ultracapacitor according to claim 1, it is characterised in that described transparent base is transparent rubber Film, sheet rubber, plastic foil, plastic sheet, glass-film or sheet glass.
7. 7. transparent ultracapacitor according to claim 1, it is characterised in that described clear gel electrolyte be sulfuric acid/ Polyvinyl alcohol/water or phosphoric acid/polyvinyl alcohol/water.
8. 8. transparent ultracapacitor according to claim 1, it is characterised in that described collector is metal foil, metal wire Or metal film.
9. 9. transparent ultracapacitor according to claim 1, it is characterised in that described conductive material be conductive silver paste or Conducting resinl.