阅读说明：本技术 一种用于摩擦发电机的复合柔性碳凝胶电极及其制备方法 (Composite flexible carbon gel electrode for friction generator and preparation method thereof ) 是由 胡陈果 刘怡珂 刘文林 郭恒宇 于 2020-03-07 设计创作，主要内容包括：本发明公开了一种用于摩擦发电机的复合柔性碳凝胶电极及其制备方法,以及具有该柔性电极的摩擦发电机,所述柔性电极包括导电碳凝胶,导电碳凝胶由微米级的粗碳粉、纳米级的细碳粉和柔性硅胶按一定比例制成。本发明提供的复合柔性碳凝胶电极,材料新颖,能够极大提高摩擦发电机两个摩擦层的有效接触面积,可以使得摩擦发电机的接触效率从6.16％提高至54.98％,且该柔性电极的使用寿命久,不易磨损；本发明提供的柔性碳凝胶电极的制备方法,工艺流程简单,经济有效,适合于应用与推广。(The invention discloses a composite flexible carbon gel electrode for a friction generator, a preparation method thereof and the friction generator with the flexible electrode. The composite flexible carbon gel electrode provided by the invention is novel in material, can greatly improve the effective contact area of two friction layers of the friction generator, can improve the contact efficiency of the friction generator from 6.16% to 54.98%, and is long in service life and not easy to wear; the preparation method of the flexible carbon gel electrode provided by the invention is simple in process flow, economic and effective, and suitable for application and popularization.)

1. The composite flexible carbon gel electrode for the friction generator is characterized by comprising conductive carbon gel, wherein the conductive carbon gel is prepared by mixing micron-sized coarse carbon powder, nanometer-sized fine carbon powder and flexible silica gel according to a certain proportion.

2. The composite flexible carbon gel electrode for a triboelectric generator as claimed in claim 1, wherein the coarse carbon powder and the fine carbon powder are in the following ratio (4-7): (1.5-3): 60 percent of the total amount of the active ingredients is added into the flexible silica gel to manufacture the gel electrode.

3. The composite flexible carbon gel electrode for the friction generator as claimed in claim 1, wherein the flexible silica gel is bi-component silica gel, and is prepared by uniformly mixing and solidifying liquid A and liquid B, and the volume ratio of the liquid A to the liquid B is 1: 2-2: 1.

4. A composite flexible carbon gel electrode for a triboelectric generator according to claim 1, wherein the conductive carbon gel is attached by self-adsorption with a buffer layer.

5. The composite flexible carbon gel electrode for a triboelectric generator according to claim 4, wherein the surface of the buffer layer is provided with a groove structure, the conductive carbon gel being arranged within the grooves of the buffer layer.

6. A method of making a composite flexible carbon gel electrode according to claims 1-5, comprising the steps of:

s1, mixing and uniformly stirring silica gel A, B according to a volume ratio of 1: 2-2: 1 to obtain mixed silica gel for later use;

s2, adding the nano carbon powder into the uniformly stirred mixed silica gel according to the weight ratio of the nano carbon powder to the mixed silica gel of 1: 40-1: 20, and uniformly stirring again;

s3, adding the micron carbon powder into the mixed silica gel doped with the nano carbon powder according to the weight ratio of the micron carbon powder to the mixed silica gel of 1: 15-7: 60, and uniformly stirring;

s4, manufacturing a buffer layer with a groove, pouring the mixture obtained in the step S3 into the groove, leveling, and covering a piece of smooth weighing paper on the surface of the buffer layer; clamping the prepared sample between two substrates, and placing the sample on a bench vice to extrude for 6-10 h;

and S5, taking out the sample, and slightly removing the weighing paper to obtain the composite flexible carbon gel electrode arranged in the buffer layer.

7. The method for preparing a composite flexible carbon gel electrode as claimed in claim 6, wherein in step S3, micron carbon powder is added into the mixed silica gel doped with nano carbon powder in batches.

8. A triboelectric generator comprising an upper electrode and a lower electrode capable of contacting and separating, and a dielectric film provided on a lower surface of the upper electrode and/or on an upper surface of the lower electrode, characterized in that at least one of the upper electrode and the lower electrode is the composite flexible carbon gel electrode according to any one of claims 1 to 5.

9. The triboelectric generator according to claim 8, wherein said lower electrode is said composite flexible carbon gel electrode, said dielectric film being adsorbed on a conductive carbon gel of said composite flexible carbon gel electrode; the friction generator further comprises a buffer layer and an arched substrate; the composite flexible carbon gel electrode is arranged on the buffer layer, the buffer layer is arranged on the arched substrate, the arched substrate is arranged on the lower substrate, and the upper electrode is arranged below the upper substrate.

10. The triboelectric generator according to claim 8, wherein the arched substrate is convex in the middle and concave at both sides, the arched substrate has a parabolic cross section, the ratio of the maximum height H of the arched substrate to the length L of the arched substrate is 1:10 to 1:100, or the arched substrate has a concave middle and convex at both sides, the arched substrate has a parabolic cross section with an upward opening, and the ratio of the maximum depth H of the arched substrate concave middle to the length L of the arched substrate is 1:10 to 1: 100.

Technical Field

The invention relates to the technical field of friction generators, in particular to a composite flexible carbon gel electrode for a friction generator, a preparation method of the composite flexible carbon gel electrode and the friction generator with the composite flexible carbon gel electrode.

Background

A triboelectric generator (TENG) based on triboelectrification and electrostatic induction can be used for collecting mechanical energy in the environment, and is a novel power generation device. In general, the two rubbing layers of TENG in vertical contact separation mode are composed of two materials with different properties, with the metal and dielectric being chosen according to the difference in surface potential.

Specifically, the TENG based on triboelectrification and electrostatic induction has two friction layers, namely two dielectric films, or a dielectric film and an electrode, and the output of TENG energy depends on the contact and separation of the two friction layers. In practical application, because the surface of the material is not absolutely flat, a part of micron-sized air gaps exist in a contact state, so that the actual effective contact area of the two friction layers is smaller than the actual areas of the electrode and the friction layers, and the output charge is greatly reduced. Therefore, what influences TENG to be applied further to real life is its output charge density, and the contact area between metal and dielectric is an important factor influencing the output charge density of a friction generator (TENG). Therefore, the contact area of the friction generator is increased, and the contact area is accurately and strictly calculated, so that the important significance is provided for further evaluating the charge density of the friction generator.

For conventional triboelectric generators, the contact area is typically increased by adding a flexible substrate to increase the contact area by deforming the substrate, or by treating the surface of the friction material to increase the micro-surface area. Such as adding a foam base to the bottom of the device or using a liquid pad, etc. While these approaches do improve output by increasing contact area to some extent, such increases are extremely limited. Moreover, these methods are cumbersome to operate and increase the weight and volume of TENG itself. An article entitled "nanogold mesoporous as an effective dielectric material for improving the performance of a triboelectric nanogenerator under severe environments (triboelectric nanogenerator performance in a harsh environment)" published in Energy and Environmental Science (Energy & Environmental Science) in 2015 proposes a method for manufacturing a large-volume mesoporous Polydimethylsiloxane (PDMS) film by casting a mixture of a PDMS solution and deionized water and evaporating water very slowly at room temperature, and increases the effective contact area of a mesoporous friction layer by manufacturing the mesoporous polydimethylsiloxane, thereby improving the output performance of TENG. However, the charge density, current density provided by this approach is still limited. Therefore, it is desired to develop a novel electrode material capable of greatly increasing the effective contact area of an electrode.

In addition, in the existing research work, the effective contact area is measured by experience, which not only can not describe the contact area strictly and quantitatively, but also causes great errors in calculating physical quantities such as power density and charge density. Therefore, it is necessary to invent a method capable of accurately quantifying the contact area, which is also significant for the development of the friction generator.

Disclosure of Invention

The present invention is designed to solve at least the above technical problems, and in order to achieve the above object, according to a first aspect of the present invention, there is provided a composite flexible carbon gel electrode for a friction generator, including a conductive carbon gel, wherein the conductive carbon gel is prepared by mixing micron-sized coarse carbon powder, nanometer-sized fine carbon powder, and flexible silica gel in a certain ratio.

Further, the coarse carbon powder and the fine carbon powder are prepared according to the following steps of (4-7): (1.5-3): 60 percent of the total amount of the active ingredients is added into the flexible silica gel to manufacture the gel electrode.

Furthermore, the flexible silica gel is bi-component silica gel and is prepared by uniformly mixing and solidifying the liquid A and the liquid B, and the volume ratio of the liquid A to the liquid B is 1: 2-2: 1. The solidification degree can be adjusted by regulating the proportion of the liquid A and the liquid B, and the semi-solidified state is optimal after carbon powder is mixed. Further, the volume ratio of the solution A to the solution B is 1: 1.

Further, the conductive carbon gel is connected with the buffer layer through self-adsorption force.

Furthermore, the surface of buffer layer is provided with the groove structure, electrically conductive carbon gel sets up in the recess of buffer layer. Preferably, the cushioning layer may be foam.

According to a second aspect of the present invention, there is provided a method for preparing a composite flexible carbon gel electrode, comprising the steps of: s1, mixing and uniformly stirring silica gel A, B according to a volume ratio of 1: 2-2: 1 to obtain mixed silica gel for later use; s2, adding the nano carbon powder into the uniformly stirred mixed silica gel according to the weight ratio of the nano carbon powder to the mixed silica gel of 1: 40-1: 20, and uniformly stirring again; s3, adding the micron carbon powder into the mixed silica gel doped with the nano carbon powder according to the weight ratio of the micron carbon powder to the mixed silica gel of 1: 15-7: 60, and uniformly stirring; s4, manufacturing a buffer layer with a groove, pouring the mixture obtained in the step S3 into the groove, leveling, and covering a piece of smooth weighing paper on the surface of the buffer layer; clamping the prepared sample between two substrates (which can be acrylic plates), and placing the substrates on a bench vice to extrude for 6-10 h; and S5, taking out the sample, and slightly removing the weighing paper to obtain the composite flexible carbon gel electrode arranged in the buffer layer.

Further, the micron carbon powder of step S3 is added to the mixed silica gel doped with nano carbon powder in batches.

Further, the volume ratio of the silica gel A, B in the step S1 is 1: 1.

Further, the stirring time in the step S1 is 2-5min, the stirring time in the step S2 is 2-5min, and the stirring time in the step S3 is 3-10 min.

Further, the above preparation process operates at ambient temperature of 20 ℃.

According to a third aspect of the present invention there is provided a triboelectric generator comprising a composite flexible carbon gel electrode as described above.

Specifically, the friction generator comprises an upper electrode and a lower electrode which can be contacted and separated, and a dielectric film arranged on the lower surface of the upper electrode and/or arranged on the upper surface of the lower electrode, wherein at least one of the upper electrode and the lower electrode is the composite flexible carbon gel electrode.

Further, the lower electrode is the composite flexible carbon gel electrode, and the dielectric film is adsorbed on the conductive carbon gel of the composite flexible carbon gel electrode; the friction generator further comprises a buffer layer and an arched substrate; the composite flexible carbon gel electrode is arranged on the buffer layer, the buffer layer is arranged on the arched substrate, the arched substrate is arranged on the lower substrate, and the upper electrode is arranged below the upper substrate.

Furthermore, the middle of the arched substrate is convex, the two sides of the arched substrate are concave, the cross section of the arched substrate is parabolic, the ratio of the maximum height H of the middle of the arched substrate to the length L of the arched substrate is 1: 10-1: 100, or the middle of the arched substrate is concave, the two sides of the arched substrate are convex, the cross section of the arched substrate is parabolic with an upward opening, the ratio of the maximum depth H of the middle of the arched substrate to the length L of the arched substrate is 1: 10-1: 100, the contact time sequence of the contact surfaces of the electrodes and the dielectric films can be different due to the arrangement of the arched structure, so that bubbles between the contact surfaces can be discharged as much as possible, and the effective contact area between the friction layers is further improved.

Further, the friction generator is an external excitation type friction generator, the friction generator comprises a main friction generator and an excitation friction generator, and the lower electrode of the main friction generator is the composite flexible carbon gel electrode.

Furthermore, two ends of the upper electrode and the lower electrode of the friction generator are electrically connected with two diodes which are conducted in one direction and an external capacitor.

Through the technical scheme, the invention has the beneficial effects that:

(1) the composite flexible carbon gel electrode for the friction generator provided by the invention is novel in material, and can greatly improve the effective contact area of two friction layers of the friction generator. And the flexible electrode has long service life and is not easy to wear. Under the same conditions, the flexible carbon gel electrode is matched with foam and an arched substrate structure, and can be used forSo that the contact efficiency of the friction generator is improved from 6.16% to 54.98%. The increase of the contact area means the increase of the output charge density, and the invention can lead the charge density of the external excitation type friction generator to reach 2.38mC/m². The invention has an important effect on improving the output performance of the friction generator.

(2) The manufacturing method of the flexible carbon gel electrode provided by the invention is simple in process flow, economic and effective, and suitable for application and popularization.

Drawings

Fig. 1 is a schematic structural diagram of a friction generator provided by the present invention.

Fig. 2 is a side view of an arched base structure of a triboelectric generator according to the invention.

Fig. 3 is a connection circuit diagram of the friction generator provided by the invention.

Fig. 4 is a plan view of a standard vapor deposition electrode.

Fig. 5 is a side view of a standard evaporated electrode.

Fig. 6 shows the capacitance test results for a standard evaporated electrode and six different friction generators assembled.

Fig. 7 shows the output charge density of the friction generator provided by the invention under the condition of no voltage stabilization.

Fig. 8 shows the output charge density of the voltage-stabilized friction generator according to the present invention.

Fig. 9 shows the output current density of the friction generator according to the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

It should be noted that the terms "first", "second", and the like, as used herein, are used only to distinguish between different objects, and do not imply any particular sequential relationship between the objects. The terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation. Unless otherwise specified and limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may include, for example, mechanical or electrical connections, and communications between two elements, either directly or indirectly through intervening media, as well as the specific meanings of such terms as may be understood by those skilled in the art based on the context.

The invention provides a composite flexible carbon gel electrode for a friction generator, which can improve the actual contact area of a friction unit of the friction generator. The composite flexible carbon gel electrode is composed of conductive carbon gel. When the friction generator is constructed, the composite flexible carbon gel electrode is preferably placed on foam by means of self-adsorption force, and the foam is adhered to the arch structure. More preferably, the surface of the foam is provided with a groove structure, and the composite flexible carbon gel electrode is filled in the groove structure of the foam.

Further, the conductive carbon gel is composed of micron-sized coarse carbon powder, nanometer-sized fine carbon powder and flexible silica gel; the coarse carbon powder and the fine carbon powder are prepared according to the following steps of (4-7): (1.5-3): 60 percent of the total amount of the active ingredients are added into flexible silica gel to manufacture the gel electrode.

Furthermore, the flexible silica gel is prepared by uniformly mixing the liquid A and the liquid B and then solidifying, wherein the solidification degree can be adjusted by regulating the proportion of the liquid A and the liquid B, and the flexible silica gel is finally in the optimal semi-solidification state after being mixed with carbon powder.

Furthermore, the arch structure is provided with a middle bulge, two sides of the arch structure are concave, and the cross section of the arch structure is parabolic; the structure can be also arranged to be concave in the middle and convex on two sides according to the requirements.

The invention also provides a manufacturing method of the composite flexible carbon gel electrode, and the required materials comprise A, B two kinds of silica gel of Ecoflex20 model, TIMCA L conductive carbon black SUPER P L i and nano carbon powder (Suzhou carbon rich graphene science and technology Co., Ltd.).

The manufacturing method of the composite flexible carbon gel electrode (environmental temperature: 20 ℃) specifically comprises the following steps:

s1, mixing and uniformly stirring silica gel A, B according to a certain proportion (volume ratio), and stirring for a period of time for later use. The volume ratio of the silica gel A, B is 1: 2-2: 1, preferably 1: 1. The stirring time is 2-5min, preferably 3 min.

And S2, adding nano carbon powder (carbon powder: mixed silica gel is 1: 40-1: 20) in a fixed mass ratio into the uniformly stirred mixed silica gel, and stirring again. The stirring time is 2-5min, preferably 3 min.

And S3, adding micrometer carbon powder (the micrometer carbon powder: mixed silica gel is 1: 8-1: 15) in a fixed mass ratio into the mixed silica gel doped with the nanometer carbon powder (adding in batches, and taking a proper amount each time), and stirring again. In one embodiment of the present invention, the micron carbon powder is conductive carbon black. The stirring time is 3-10min, preferably 5 min.

And S4, manufacturing a buffer layer with a groove structure, pouring the mixture obtained in the step 3 into the groove, leveling, and covering a piece of smooth weighing paper on the surface of the buffer layer. The sample was then sandwiched between two acrylic plates of the same size and placed in a bench vice and pressed for 6-10 h.

And S5, finally, taking out the sample, and slightly removing the weighing paper to obtain the flexible electrode arranged in the buffer layer.

In one embodiment of the invention, the material of the cushioning layer is foam.

In another aspect, the present invention provides a triboelectric generator having the above composite flexible carbon gel electrode.

Further, the friction generator structure based on the composite flexible carbon gel electrode is as follows: the dielectric film can be directly adsorbed on the conductive carbon gel of the composite flexible carbon gel electrode to be used as a stator part, and the other electrode or the electrode attached with the dielectric film is used as a moving part so as to assemble a friction generator.

The basic structural composition of the friction generator with the composite flexible carbon gel electrode is described in the following with reference to the attached drawings.

Fig. 1 shows the basic structure of a triboelectric generator with a composite flexible carbon gel electrode of the invention. As shown in fig. 1, the friction generator TENG of the present invention includes a main friction generator 1 and an excitation friction generator 2, and the main TENG 1 and the excitation TENG 2 are connected.

The primary TENG 1 comprises an upper substrate 101, a first electrode 102, a first dielectric film 103, a second electrode 104, a buffer layer 105, a dome-shaped base 106 and a lower substrate 107. the first electrode 102 is disposed below the upper substrate 101, the second electrode 104 is disposed above the buffer layer 105, preferably, the buffer layer 105 has a groove structure 1051, the second electrode 104 is disposed within the groove 1051. the first dielectric film 103 is disposed above the second electrode 104. the buffer layer 105 is connected below the dome-shaped base 106, the dome-shaped base 106 is disposed above the lower substrate 107. the upper substrate 101 and the lower substrate 107 can be acrylic substrates. in one embodiment of the invention, the first electrode 102 is a copper electrode and the first electrode 102 can also be other metal or non-metal electrodes. in one embodiment of the invention, the first dielectric film 103 is selected to be a Polyetherimide (PEI) film, the buffer layer 105 can be a foam. in the invention, the second electrode 104 is a composite flexible gel electrode provided by the invention. in one embodiment of the invention, the dome-shaped base 106 is convex with a convex base 106 having a convex side view on two sides, a concave side view as shown in FIG. 2, the convex side view of the base 106, the convex side view of the convex base 106, the convex base is disposed on the concave side view of the base, the base 100, the convex side view of the concave base, and the convex base 10, the convex side view of the convex base, the convex side.

The excitation TENG 2 shares the upper substrate 101, the lower substrate 107, the buffer layer 105, and the arch base 106 with the main TENG 1 on the mounting structure. The excitation TENG 2 includes a third electrode 202 attached under the upper substrate 101, a second dielectric film 203 covering the third electrode 202, and a fourth electrode 204 disposed on the buffer layer, preferably, the fourth electrode 204 is directly attached on the surface of the buffer layer 105. In one embodiment of the present invention, the third electrode 202 and the fourth electrode 204 are copper electrodes, and the third electrode 202 and the fourth electrode 204 may also be other metal or non-metal electrodes. Preferably, the second dielectric film 203 is a perfluoroethylene propylene copolymer (FEP) film.

The invention also shows the electrical connection relationship of the main TENG 1 and the excitation TENG 2 of the friction generator, and particularly shows the working circuit diagram of the main TENG 1 and the excitation TENG 2 shown in figure 3. The excitation TENG 2 is connected in parallel with the main TENG 1 and the external capacitor C, and the excitation TENG is unidirectionally conducted through two diodes, so that output charges generated by the excitation TENG are unidirectionally input into the external capacitor. The charges stored in the external capacitor are partially supplemented to the main TENG 1 when the main TENG 1 is in a contact state, all the charges in the main TENG 1 flow back to the external capacitor again due to the change of the capacitance in the main TENG 1 in the separation process, and the circulation is repeated, and the charges are accumulated continuously until a stable working state is achieved.

Although the invention is illustrated in fig. 1 as an externally excited triboelectric generator, the composite flexible carbon gel electrode provided by the invention can be applied to other types of triboelectric generators as well. Preferably, the other type of friction generator has the same or similar structure as the main friction generator in fig. 1.

The invention also provides a method for measuring the effective contact area of the friction layer of the friction generator in normal operation, so as to quantify the effective contact area, and the measuring method divides the whole measuring process into seven stages:

in the first stage, the substrate is selected to be the same material (same material, same size, same thickness) as the dielectric film used in the rubbing layer of TENG.

In the second stage, the dielectric film (surface area is denoted as S)₀) Immersing in alcohol, ultrasonic treating for 10min, taking out, and wiping with dust-free cloth.

And the third stage, plating copper electrodes with the same thickness on the front and back surfaces of the dielectric film by using a vacuum evaporation method.

And in the fourth stage, two electrodes are respectively led out from the edges of the front side and the back side of the dielectric film deposited with the copper electrodes so as to facilitate subsequent testing.

In the fifth stage, the capacitance between the two evaporated electrodes is measured by an instrument and is marked as C₀。C₀I.e. as the capacitance between two plates of TENG when the two friction layers (electrodes, dielectric film) are fully in contact. From the capacitance formulaWherein_rFor the dielectric constant, d is the vertical distance between the plates, S is the plate facing area, and k is the electrostatic constant, it can be seen that the larger the contact area S (i.e., the plate facing area) is, the larger the capacitance is.

And in the sixth stage, the capacitance of the contact between the two polar plates of the TENG in normal operation is tested by using the same instrument. The peak capacitance C' of the TENG at the minimum distance between the two friction layers was recorded.

The seventh stage, using the formula S ═ S₀×η,The actual effective contact area S' and contact efficiency η for TENG are calculated.