阅读说明：本技术 一种柔性可折叠超级电容器及其制备方法 (Flexible and foldable super capacitor and preparation method thereof ) 是由 刘先斌 邹帅 吴子平 尹艳红 黎业生 于 2019-09-24 设计创作，主要内容包括：本发明属于新型先进能源存储器件技术领域,公开了一种柔性可折叠超级电容器及其制备方法,选择碳纳米管宏观膜作为集流体,表面负载活性物质构建近一体化复合电极；然后通过干燥、裁片、焊接、叠片、组装、注液和封装工艺制备柔性可折叠超级电容器。本发明碳纳米管宏观膜集流体与活性物质层间通过相互嵌入锚合作用形成近一体化的复合电极,该复合电极界面结构稳定、电子/离子的传导/扩散高效,同时多孔的碳纳米管宏观膜集流体能够储存电解液保证了电化学性能的稳定性。基于此组装的超级电容器具备高的体积能量密度、能任意弯曲折叠,适应工作温度宽,能应用于各式便携式电子设备、而且制备方法简单,便于大规模开发和应用。(The invention belongs to the technical field of novel advanced energy storage devices, and discloses a flexible foldable super capacitor and a preparation method thereof, wherein a carbon nano tube macroscopic film is selected as a current collector, and a near-integrated composite electrode is constructed by loading active substances on the surface; and then preparing the flexible foldable super capacitor through the processes of drying, cutting, welding, laminating, assembling, injecting liquid and packaging. The carbon nano tube macroscopic film current collector and the active substance layer form a nearly integrated composite electrode through mutual embedding and anchoring, the composite electrode has stable interface structure and high efficiency of electron/ion conduction/diffusion, and meanwhile, the porous carbon nano tube macroscopic film current collector can store electrolyte to ensure the stability of electrochemical performance. The assembled super capacitor has high volume energy density, can be bent and folded at will, is suitable for wide working temperature, can be applied to various portable electronic devices, has a simple preparation method, and is convenient for large-scale development and application.)

1. A preparation method of a flexible foldable super capacitor based on a carbon nano tube macroscopic film near-integration electrode is characterized in that the preparation method of the flexible foldable super capacitor based on the carbon nano tube macroscopic film near-integration electrode selects a carbon nano tube macroscopic film as a current collector, and active substances are loaded on the surface of the current collector to construct a near-integration composite electrode;

and then preparing the flexible foldable super capacitor through the processes of drying, cutting, welding, laminating, assembling, injecting liquid and packaging.

2. The method for preparing the flexible and foldable supercapacitor based on the carbon nanotube macroscopic film near-integrated electrode according to claim 1, wherein the composite electrode is prepared by a coating method, electrostatic spinning, a liquid phase method and an electrochemical deposition method.

3. The method for preparing the flexible and foldable supercapacitor based on the carbon nanotube macroscopic film near-integrated electrode as claimed in claim 1, wherein the method for preparing the flexible and foldable supercapacitor based on the carbon nanotube macroscopic film near-integrated electrode specifically comprises:

step one, preparing a pole piece: firstly, weighing an active substance, a conductive agent and a binder according to a ratio of 8:1:1, then adding the binder into an N, N-dimethylformamide solvent, placing the N, N-dimethylformamide solvent at a high temperature of 100 ℃ for accelerated dissolution at 120 ℃, continuously adding the active substance and the conductive agent for stirring after the binder is fully dissolved, placing the mixed raw materials into an agate tank, placing the raw materials into a planetary ball mill, preparing slurry with proper viscosity after ball milling for 12 hours, then uniformly coating the slurry on the surface of a flattened carbon nanotube macroscopic film current collector, and finally placing a pole piece into a drying box for drying;

secondly, assembling the super capacitor: cutting the dried pole piece according to a fixed size, welding a pole lug, stacking the pole piece, a diaphragm and the pole piece in sequence, and finally assembling by using an outer packaging film to obtain the super capacitor;

thirdly, liquid injection and packaging of the super capacitor: and injecting an electrolyte into the prepared super capacitor, standing for 24 hours, and then performing air exhaust and packaging to obtain the final super capacitor.

4. The method for preparing the flexible and foldable super capacitor based on the carbon nanotube macroscopic film near-integrated electrode as claimed in claim 3, wherein in the first step, the carbon nanotube macroscopic film is orderly or disorderly arranged to form a porous structure for adsorbing and storing the electrolyte.

5. The method for preparing the flexible foldable super capacitor based on the carbon nanotube macroscopic film near-integration electrode as claimed in claim 3, wherein in the first step, the electrode is formed by embedding and anchoring the carbon nanotube macroscopic film current collector and the active material into each other to form a near-integration composite electrode structure.

6. The method for preparing the flexible foldable super capacitor based on the carbon nano tube macroscopic film near-integration electrode as claimed in claim 3, wherein in the first step, the active material adopts activated carbon, graphene, conductive polymer and metal compound; the conductive polymer comprises polyaniline, polypyrrole and polythiophene; the metal compounds include manganese dioxide, ruthenium oxide and titanium carbide.

7. The method for preparing a flexible and foldable supercapacitor based on carbon nanotube macroscopic film near-integrated electrodes according to claim 3, wherein in the first step, the thickness of the carbon nanotube macroscopic film is 1-50 μm; the surface density is 0.1-1mg/cm²。

8. The method for preparing the flexible and foldable super capacitor based on the carbon nano tube macroscopic film near-integrated electrode as claimed in claim 3, wherein in the first step, the coating thickness of the active material is 10-200 μm, and the loading capacity is 1-20mg/cm²。

9. The method for preparing the flexible foldable super capacitor based on the carbon nano tube macroscopic film near-integrated electrode as claimed in claim 3, wherein in the second step, the size of the electrode cut piece is 20cm x 20 cm;

in the third step, the energy density of the super capacitor is higher than 50 Wh/kg; the operating cut-off voltage was 2.7V.

10. A flexible foldable super capacitor based on a carbon nanotube macroscopic film near-integrated electrode, prepared by the method for preparing the flexible foldable super capacitor based on the carbon nanotube macroscopic film near-integrated electrode as claimed in any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of novel advanced energy storage devices, and particularly relates to a flexible foldable super capacitor and a preparation method thereof.

Background

Currently, the closest prior art:

with the rapid development of modern science and technology, various portable wearable intelligent electronic devices come out in succession, and these electronic devices gradually develop towards miniaturization, planarization, flexibility and the like, and can even continuously and stably work under various special environments such as pressing, pulling, folding and the like. However, the existing energy storage and supply devices are often too thick, too heavy and poor in flexibility, and cannot well meet the requirements of the emerging industry, so that the key for developing the multifunctional wearable electronic equipment is to develop an energy storage device matched with the multifunctional wearable electronic equipment, and the energy storage device is required to have long endurance capacity, and more importantly, to be capable of maintaining a stable working state under the special environmental conditions. Therefore, the research on the novel high-performance flexible foldable energy storage device has very important significance.

Super capacitors have received much attention as an efficient, clean, sustainable energy source. The super capacitor has the advantages of high power density, good low-temperature performance, long service life (up to tens of thousands of times), high safety and the like, and meanwhile, the super capacitor serving as an energy storage element also develops towards the directions of small size, light weight, flexibility and the like. The energy density of the conventional super capacitor is low, and meanwhile, because metals such as nickel, copper and aluminum are selected as a current collector, the super capacitor is easy to crack under the deformation condition including bending, winding, folding and the like, the metal current collector is broken even and then transmission of electrons is blocked, in addition, electrolyte on the surface of the current collector is extruded under the deformation action, diffusion of ions is inhibited, and meanwhile, active substances loaded on the surface are easy to fall off and separate, so that the performance of the super capacitor is attenuated and even loses efficacy, and therefore, the flexible current collector is developed and applied to the super capacitor, and the super capacitor has important value.

The flexible electrode is expected to realize the flexibility of the supercapacitor by further constructing the flexible electrode by preparing the flexible carbon-based current collector, for example, active substances are loaded on current collectors such as carbon cloth and carbon nano tubes by hydrothermal method, electrochemical deposition and other technologies. Then, there is also an interface problem between the active material and the current collector: in order to solve the interface problem, the Zheng Bo introduces graphene as a bridging point between a current collector (foam carbon, foam carbon cloth) and an active material, enriches the transmission path of electrons, and improves the structural stability and electrochemical characteristics of the device (adv. mater.2013,25, 5799-doped 5806). It is noted that after the graphene is introduced, the graphene and the current collector generate an interface again. Recently, Yongmin Ko et al adopt a chemical self-assembly method to improve the contact problem between a flexible substrate (non-conductive substrate) and an active material, and improve the flexibility of a super capacitor device (nat. Comm.,2017,8(1): 536).

However, the current collectors have no flexibility or conductivity, and cannot achieve both excellent flexibility and high conductivity, thereby limiting the development of flexible supercapacitors. Therefore, the interface structure needs to be further optimized, so that the interface problems of electron transmission, structural stability and the like are essentially solved, and the flexible and foldable super capacitor with high energy density and power density is realized.

In summary, the problems of the prior art are as follows:

(1) in the prior art, the flexible characteristic and the conductive characteristic of a supercapacitor device cannot be optimized at the same time, so that the development of a flexible supercapacitor is limited. And the preparation method of the super capacitor in the prior art is complex, and is not convenient for large-scale development and application.

(2) In the prior art, active substances are grown in situ, and the loading capacity of the active substances is low, so that the overall energy density of the device is low, and the long-time energy requirement of intelligent electronic equipment cannot be met.

(3) In the prior art, the prepared super capacitor is in a flexible folding process, electrolyte is subjected to external force, and secondary distribution of the electrolyte is uneven on the surface of an electrode, so that energy supply of the super capacitor is influenced, and stable work in a flexible and foldable environment cannot be truly realized.

The difficulty of solving the technical problems is as follows:

the preparation of the flexible current collector, the stable loading of the active material and the uniform distribution of the electrolyte in the electrode.

The significance of solving the technical problems is as follows: the flexible foldable super capacitor is prepared on a large scale, the electronic transmission, the charge diffusion and the stability of the device are improved, and the stable and normal operation of the device in a flexible foldable environment is met.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a flexible foldable super capacitor and a preparation method thereof.

The invention is realized in such a way, the method for preparing the flexible foldable super capacitor based on the carbon nano tube macroscopic film near-integration electrode selects the carbon nano tube macroscopic film as a current collector, active substances are loaded on the surface of the current collector to construct the near-integration composite electrode, and then the flexible foldable super capacitor is prepared by the processes of drying, cutting, welding, laminating, assembling, injecting liquid, packaging and the like.

The method comprises the following specific steps:

step one, preparing a pole piece: firstly, weighing an active substance, a conductive agent and a binder according to a ratio of 8:1:1, then adding the binder into an N, N-dimethylformamide solvent, placing the solvent at a high temperature of 100 ℃ and 120 ℃ for accelerated dissolution, after the binder is fully dissolved, continuously adding the active substance and the conductive agent for stirring, placing the mixed raw materials into an agate tank, placing the tank into a planetary ball mill, preparing slurry with proper viscosity after ball milling for 12h, then uniformly coating the slurry on the surface of a flattened carbon nanotube macroscopic film current collector, and finally placing a pole piece into a drying box for drying.

Secondly, assembling the super capacitor: and cutting the dried pole piece according to a fixed size, welding a pole lug, stacking the pole piece, the diaphragm and the pole piece in sequence, and finally assembling the pole piece and the diaphragm by using an outer packaging film to obtain the supercapacitor.

Thirdly, liquid injection and packaging of the super capacitor: and injecting an electrolyte into the prepared super capacitor, standing for 24 hours, and then performing air exhaust and packaging to obtain the final super capacitor.

Furthermore, the carbon nanotube macroscopic film has excellent conductivity and physical and mechanical properties, and more importantly, the porous structure formed by ordered or disordered arrangement of the carbon nanotube macroscopic film can adsorb and store electrolyte.

Furthermore, the electrode is formed by embedding and anchoring a carbon nano tube macroscopic film current collector and an active substance into each other to form a nearly integrated structure.

Further, as the active material, mainly used are activated carbon, graphene, a conductive polymer (polyaniline, polypyrrole, polythiophene, and the like), a metal compound (manganese dioxide, ruthenium oxide, titanium carbide, and the like), and the like.

Further, the composite electrode is prepared by a coating method, electrostatic spinning, a liquid phase method, an electrochemical deposition method and other processes.

Furthermore, the thickness of the carbon nano tube macroscopic film is 1-50 μm. The surface density is 0.1-1mg/cm²。

Further, the coating thickness of the active substance is 10-200 μm, and the loading is 1-20mg/cm²。

Furthermore, the size of the electrode cutting piece can reach 20cm multiplied by 20 cm.

Further, the energy density may be higher than 50 Wh/kg.

Furthermore, the flexible foldable super capacitor can be bent and folded at any angle, and the flexible foldable super capacitor can still normally work after the bending and folding cycle times are more than 1000.

Further, the flexible foldable super capacitor can work normally under severe environments such as low temperature (< 40 ℃), low voltage (< 0.1Kpa) and the like.

The invention also aims to provide a flexible foldable super capacitor based on the carbon nano tube macroscopic film near-integrated electrode, which is prepared by the preparation method of the flexible foldable super capacitor based on the carbon nano tube macroscopic film near-integrated electrode.

In summary, the advantages and positive effects of the invention are: the electrode has the advantages that the flexibility is excellent, the conductivity is high, the carbon nano tube macroscopic film is used as a current collector, active substances are loaded on the surface of the current collector to prepare a nearly integrated electrode, the porous carbon nano tube macroscopic film can anchor the active substances, the structural stability of the electrode in the folding process is guaranteed, meanwhile, the uniform distribution of electrolyte can be realized, and the stable and excellent electrochemical energy storage characteristic is displayed.

In order to enable the energy storage device to be more flexible so as to meet the requirements of portable electronic equipment, the invention selects the carbon nano tube macroscopic film as a current collector surface loaded with active substances to prepare an electrode, and the preparation of the flexible foldable super capacitor is realized through processes of cutting, welding, laminating, assembling, injecting liquid, packaging and the like. The carbon nano tube macroscopic film current collector and the active substance layer form a nearly integrated composite electrode through mutual embedding and anchoring, the composite electrode has stable interface structure and high efficiency of electron/ion conduction/diffusion, and meanwhile, the porous carbon nano tube macroscopic film current collector can store electrolyte to ensure the stability of electrochemical performance. The assembled super capacitor has high volume energy density, can be bent and folded randomly (the radius is less than 1mm), is suitable for wide working temperature, can be applied to various portable electronic devices, has a simple preparation method, and is convenient for large-scale development and application.

Drawings

Fig. 1 is a flow chart of a method for preparing a flexible foldable supercapacitor based on a carbon nanotube macroscopic film near-integration electrode according to an embodiment of the invention.

Fig. 2 is a schematic diagram of a supercapacitor and an electrode structure thereof according to an embodiment of the present invention.

Fig. 3 is a scanning electron micrograph of carbon nanotube fibers according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a composite electrode based on a carbon nanotube macroscopic film current collector according to an embodiment of the present invention.

Fig. 5 is a display diagram showing the operation of the flexible and foldable super capacitor provided by the embodiment of the invention in different bending states.

Fig. 6 is a specific capacity variation curve diagram of the flexible and foldable supercapacitor provided by the embodiment of the invention under different deformation states.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.