Capacitor, flexible transparent carbon fiber web, and electronic device

Abstract

The application discloses a capacitor, a flexible transparent carbon fiber net and an electronic device. The flexible transparent carbon fiber net is prepared by applying cobalt nitrate and imidazole and its derivatives on silk respectively, growing cobalt complexes in situ on the surface and / or pores of the silk, forming silk loaded with the cobalt complexes, and then performing heat treatment on the silk loaded with the cobalt complexes under a protective atmosphere, and further combining acid etching. The flexible transparent carbon fiber net of the application has excellent flexibility, electrochemical performance and light transmittance, can be applied as an electrode in a capacitor, and is helpful to the preparation of a flexible portable electronic device.

Description

[0001] The present application is a divisional application of the Chinese Invention Patent Application No. 2024114195070, entitled "Electrode Material and Preparation Method Thereof, Electrode, Battery, Flexible Transparent Carbon Fiber Web and Preparation Method Thereof, Capacitor, Electronic Device", filed on October 12, 2024. TECHNICAL FIELD

[0002] The present application relates to the field of capacitor materials, in particular to a capacitor, a flexible transparent carbon fiber web and an electronic device. BACKGROUND

[0003] With the continuous development of science and technology, various portable electronic devices play an increasingly important role in daily life, and their functions are becoming more and more diversified, which not only improves the user experience but also puts forward higher requirements for their power supply and energy storage devices. Lithium ion batteries have become the first choice for power supply of flexible wearable devices and mobile portable electronic devices because of their relatively mature production technology, higher energy density compared to other types of batteries, and the ability to be repeatedly charged and discharged, and environmental friendly characteristics. However, with the continuous improvement of user demand, one of the final development directions of portable electronic devices may be flexible folding, which can further save space while ensuring user experience, which requires the power supply device to also have corresponding flexibility. However, the stretching strain of the battery assembly of the commercialized lithium ion battery at the present stage is low, and the flexibility is relatively insufficient, which is damaged after multiple bending tests. SUMMARY

[0004] The purpose of the present application is to overcome one or more deficiencies in the prior art, and to provide an improved preparation method of a flexible transparent carbon fiber web capable of having flexibility, excellent electrochemical performance and light transmission, and a flexible transparent carbon fiber web prepared by the method, and a capacitor comprising the flexible transparent carbon fiber web.

[0005] The present application also provides an electronic device comprising the capacitor described above, so that the electronic device can have flexible folding performance.

[0006] To achieve the above-mentioned purpose, one technical solution adopted by the present application is: a preparation method of an electrode material, the preparation method comprising:

[0007] Applying cobalt nitrate and a compound represented by formula (I) on silk respectively, growing cobalt complexes in situ on the surface and / or pores of the silk to form silk loaded with cobalt complexes;

[0008] , R1, R2 are independently selected from C 1-3 alkyl, n is 0, 1 or 2;

[0009] The cobalt complex loaded silk is heat-treated at 700-950℃ under a protective atmosphere to obtain the electrode material.

[0010] The electrode material comprises nitrogen-doped porous carbon and nano-metallic cobalt loaded on the surface of the nitrogen-doped porous carbon and / or encapsulated in the pore structure of the nitrogen-doped porous carbon.

[0011] According to some preferred and specific aspects of the present application, the preparation method further comprises:

[0012] The cobalt nitrate solution and the compound solution of formula (I) are respectively prepared.

[0013] The silk is first soaked in one of the cobalt nitrate solution and the compound solution of formula (I) and then soaked in the other.

[0014] In some embodiments of the present application, the cobalt nitrate solution and the compound solution of formula (I) respectively use water as a solvent.

[0015] According to some specific aspects of the present application, the molar concentration of the cobalt nitrate solution is 0.5-1.5 mol / L, for example, it can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, etc.

[0016] According to some specific aspects of the present application, the molar concentration of the compound solution of formula (I) is 1.5-3.0 mol / L, for example, it can be 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3.0 mol / L, etc.

[0017] According to some preferred aspects of the present application, the silk is first soaked in the cobalt nitrate solution for X1 min and then soaked in the compound solution of formula (I) for X2 min, X1:X2 = 1.5-3:1.

[0018] In some embodiments of the present application, X1 is 15-25 and X2 is 5-15.

[0019] In some embodiments of the present application, R1 is selected from methyl, ethyl or propyl, and n is 0.

[0020] In some embodiments of the present application, R1, R2 are independently selected from methyl, ethyl or propyl, and n is 1 or 2.

[0021] According to some specific aspects of the present application, the compound of formula (I) is a combination of one or more selected from 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole.

[0022] According to some preferred aspects of the present application, the amount of the cobalt nitrate added is 0.015-0.05 mmol per square centimeter of the silk fabric.

[0023] According to some preferred aspects of the present application, the amount of the compound of formula (I) added is 0.03-0.1 mmol per square centimeter of the silk fabric.

[0024] In some embodiments of the present application, the silk fabric is mulberry silk. According to a specific aspect of the present application, the silk fabric is a 5.5 mm commercial mulberry silk.

[0025] In some embodiments of the present application, the preparation method further comprises: before the heat treatment, washing the cobalt complex-loaded silk fabric and drying treatment.

[0026] In some embodiments of the present application, the washing is performed using deionized water.

[0027] In some embodiments of the present application, the drying treatment is vacuum drying. Further, the temperature of the drying treatment is 50-70℃. Still further, the time of the drying treatment is 1-3 h.

[0028] According to some preferred aspects of the present application, the heat treatment is performed at 750-850℃.

[0029] In some embodiments of the present application, the heat treatment is performed for 1-6 h, further for 1-3 h.

[0030] According to the present application, the nitrogen-doped porous carbon is a carbon fiber mesh structure formed by interweaving a plurality of carbon fibers.

[0031] According to the present application, the electrode material is in a transparent state.

[0032] In some embodiments of the present application, the diameter of the carbon fiber is 30-500 nm, further 100-200 nm.

[0033] The present application further provides an electrode material prepared by the above-mentioned preparation method of the electrode material.

[0034] The application provides another technical scheme: an electrode, wherein the electrode comprises the electrode material.

[0035] The application provides another technical scheme: a battery comprising a positive electrode and a negative electrode, wherein any one of the positive electrode and the negative electrode is the electrode.

[0036] Further, the battery is a lithium ion battery.

[0037] The application provides another technical scheme: a preparation method of a flexible transparent carbon fiber net, wherein the preparation method comprises the following steps:

[0038] Cobalt nitrate and a compound shown in formula (I) are applied on silk respectively, and a cobalt complex is in-situ grown on the surface and / or pores of the silk to form cobalt complex loaded silk;

[0039] , wherein R1 is C 1-3 alkyl, R2 is H or C 1-3 alkyl, and n is 1 or 2.

[0040] The cobalt complex loaded silk is heat-treated at 700-950 DEG C under a protective atmosphere to obtain an intermediate;

[0041] Then, the intermediate is subjected to acid etching to obtain the flexible transparent carbon fiber net.

[0042] Further, the acid etching is performed by using hydrochloric acid. In some embodiments of the application, the molar concentration of the hydrochloric acid can be 0.5-3 mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3.0 mol / L, etc.

[0043] According to some specific aspects of the application, the etching time of the acid etching is controlled to be 10-60 min.

[0044] In some embodiments of the application, the flexible transparent carbon fiber net has a pore structure with a size of 20-30 nm.

[0045] In some embodiments of the present application, the protective atmosphere is formed by passing nitrogen and / or an inert gas.

[0046] The present application provides a flexible transparent carbon fiber mesh prepared by the method.

[0047] The present application provides a capacitor comprising a positive electrode, a negative electrode, and an electrolyte existing between the positive electrode and the negative electrode, any one of the positive electrode and the negative electrode comprising the flexible transparent carbon fiber mesh.

[0048] The present application provides an electronic device having the battery or the capacitor.

[0049] Further, the electronic device comprising the battery or the capacitor can help to make a flexible foldable portable electronic device or a wearable electronic device.

[0050] Due to the above technical solutions, the present application has the following advantages compared with the prior art:

[0051] Silk is a common biomass material, and its annual output is very large. The structure of silk is composed of silk fibroin and sericin protein. Under high temperature conditions, the protein molecules are rearranged in the pyrolysis process. In the present application, by controlling the temperature of heat treatment, the protein molecules of silk are converted into sp 2 Hybrid carbon hexagonal structure, thereby forming a conductive material, while containing a high content of nitrogen element;

[0052] In the present application, by loading cobalt complexes formed by cobalt and nitrogen-containing imidazole compounds on silk before heat treatment, especially by in-situ synthesis method to uniformly deposit the cobalt complexes on the surface and pores of silk fibers, after heat treatment, not only a transparent and flexible porous carbon-based electrode material can be prepared, but also the ligand of the complex can generate nitrogen-doped porous carbon during calcination, while the cobalt ions are reduced to nano metal cobalt and loaded on the surface of the porous carbon and / or encapsulated in the pore structure of the porous carbon; further, when the electrode material after heat treatment is subjected to acid etching in an etching manner, the prepared material is helpful to be applied as an electrode in a capacitor.

[0053] Based on the above material and / or method, the lithium battery has good rate, cycle performance, and small polarization phenomenon; the material used for preparing a capacitor also shows good electrochemical performance, light transmittance and flexibility.

[0054] Further, the present application can achieve the following technical effects:

[0055] (1) The material is easy to obtain, low in cost, and simple in preparation process, and is suitable for large-scale production.

[0056] (2) As a transparent negative electrode for preparing a lithium battery, the initial reversible capacity thereof can reach 1060 mAh·g -1 , the discharge voltage platform is 0.75 V, and the cycle performance is excellent (the battery capacity can reach 1000 mAh·g -1 after 475 cycles at a current density of 4 A·g -1 ).

[0057] (3) As a transparent negative electrode for preparing a transparent capacitor, the surface capacity of the capacitor is as high as 0.227 mF / cm 2 , and the capacitor can still maintain 78% of the initial capacity after 2000 cycles in a cycle stability test.

[0058] (4) In a bending test, the electrode material, the flexible transparent carbon fiber net, and the prepared capacitor can still work normally and are basically not damaged after 200 bends. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 FIG. 1 is a schematic diagram of the preparation process of the electrode material of the present application;

[0060] Figure 2 FIG. 2 is an SEM and TEM diagram of the electrode material obtained after heat treatment in the preparation process of Example 1;

[0061] Figure 3 FIG. 3 is an XRD diagram of the electrode material obtained after heat treatment in the preparation process of Example 1;

[0062] Figure 4 FIG. 4 is a real object diagram of the electrode material prepared in Example 1;

[0063] Figures 5 to 7 FIG. 5 is a performance diagram of the lithium battery prepared based on the electrode material obtained in Example 1; wherein, Figure 5 is the rate performance of the battery at different current densities, Figure 6 is a cycle performance test diagram of the battery, Figure 7 is a voltage-capacity curve diagram of the battery;

[0064] Figure 8 FIG. 6 is a TEM diagram and a HRTEM diagram of the flexible transparent carbon fiber net prepared in Example 5;

[0065] Figure 9 FIG. 7 is a performance diagram of the capacitor prepared based on the flexible transparent carbon fiber net obtained in Example 5;

[0066] Figure 10Capacitance capacity of capacitors prepared from flexible transparent carbon fiber mesh obtained in different examples (Example 5-Example 8) are compared in the following graph;

[0067] Figure 11 Capacitance capacity of capacitors prepared from carbon fiber mesh obtained in Comparative Example 1 is plotted against cycle number in the following graph;

[0068] Figure 12 Cyclic voltammograms of capacitors constructed from flexible transparent carbon fiber mesh obtained in Example 5 after 200 bending cycles are compared in the following graph. DETAILED DESCRIPTION

[0069] The above solutions are further explained in connection with the following specific examples. It should be understood that the examples are given to illustrate the basic principles, main features and advantages of the present application, and the present application is not limited in scope by the examples described below; the implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not mentioned are usually the conditions in conventional experiments.

[0070] In the following examples, all raw materials are commercially available or prepared by conventional methods in the art, unless otherwise specified.

[0071] In the following examples, the silk is commercial mulberry silk with a size of 5.5 mm, and the cobalt nitrate solution and 2-methylimidazole solution are aqueous solutions.

[0072] Example 1:

[0073] This example provides an electrode material and a preparation method thereof, and the preparation method of the electrode material comprises the following steps:

[0074] S1, first prepare 30 mL of 1 mol / L cobalt nitrate solution, labeled as solution A, and then prepare 30 mL of 2-methylimidazole solution with a concentration of 2 mol / L, labeled as solution B;

[0075] S2, first soak the silk with a size of 30 x 30 cm 2 in solution A for 20 minutes, and then soak the silk in solution B for 10 minutes, and then in-situ grow cobalt-2-methylimidazole complex on the surface and pores of the silk;

[0076] S3, wash the silk loaded with cobalt complex with deionized water for 3 times, and then dry the silk in a vacuum drying oven at 60 degrees Celsius for 2 hours after being laid flat;

[0077] S4, place the dried silk loaded with cobalt-2-methylimidazole complex in a tube furnace under nitrogen protection and heat treat for 2 hours at 800 degrees Celsius, to obtain the electrode material.

[0078] Example 2:

[0079] The example provides an electrode material and a preparation method thereof, and the preparation method of the electrode material comprises the following steps:

[0080] S1, first configure 0.5 mol / L of cobalt nitrate solution 30 mL, marked as A solution, then configure 1 mol / L of 2-methyl imidazole solution 30 mL, marked as B solution;

[0081] S2, first soak the silk with a size of 30*30cm 2 in the A solution for 20 minutes, then soak the silk in the B solution for 10 minutes, and then in-situ grow cobalt-2-methyl imidazole complex on the surface and pores of the silk;

[0082] S3, wash the cobalt complex loaded silk with deionized water for 3 times, and then dry it in a vacuum drying oven at 60 degrees Celsius for 2 hours;

[0083] S4, place the dried cobalt-2-methyl imidazole complex loaded silk in a tube furnace under nitrogen protection at 800 degrees Celsius for 2 hours to obtain an electrode material.

[0084] Example 3:

[0085] The example provides an electrode material and a preparation method thereof, and the preparation method of the electrode material comprises the following steps:

[0086] S1, first configure 0.5 mol / L of cobalt nitrate solution 30 mL, marked as A solution, then configure 1 mol / L of 2-methyl imidazole solution 30 mL, marked as B solution;

[0087] S2, first soak the silk with a size of 30*30cm 2 in the A solution for 20 minutes, then soak the silk in the B solution for 10 minutes, and then in-situ grow cobalt-2-methyl imidazole complex on the surface and pores of the silk;

[0088] S3, wash the cobalt complex loaded silk with deionized water for 3 times, and then dry it in a vacuum drying oven at 60 degrees Celsius for 2 hours;

[0089] S4, place the dried cobalt-2-methyl imidazole complex loaded silk in a tube furnace under nitrogen protection at 800 degrees Celsius for 2 hours to obtain an electrode material.

[0090] Example 4:

[0091] The example provides an electrode material and a preparation method thereof, and the preparation method of the electrode material comprises the following steps:

[0092] S1, first configure 1.5 mol / L cobalt nitrate solution 30 mL, labeled as A solution, then configure 3 mol / L 2-methyl imidazole solution 30 mL, labeled as B solution;

[0093] S2, the size of silk 30×30cm 2 First soaked in A solution for 20 minutes, then the silk is soaked in B solution for 10 minutes, then the cobalt-2-methyl imidazole complex will be in situ grown on the surface and pores of the silk;

[0094] S3, the cobalt complex loaded silk is washed with deionized water 3 times, and then placed in a vacuum drying oven at 60 degrees Celsius for drying for 2 hours;

[0095] S4, the dried cobalt-2-methyl imidazole complex loaded silk is placed in a tube furnace under nitrogen protection for heat treatment for 2 hours at 800 degrees Celsius, to obtain an electrode material.

[0096] Example 5:

[0097] The present example provides a flexible transparent carbon fiber mesh and a preparation method thereof, the preparation method of the flexible transparent carbon fiber mesh comprising the following steps:

[0098] S1, first configure 1 mol / L cobalt nitrate solution 30 mL, labeled as A solution, then configure 2 mol / L 2-methyl imidazole solution 30 mL, labeled as B solution;

[0099] S2, the size of silk 30×30cm 2 First soaked in A solution for 20 minutes, then the silk is soaked in B solution for 10 minutes, then the cobalt-2-methyl imidazole complex will be in situ grown on the surface and pores of the silk;

[0100] S3, the cobalt complex loaded silk is washed with deionized water 3 times, and then placed in a vacuum drying oven at 60 degrees Celsius for drying for 2 hours;

[0101] S4, the dried cobalt-2-methyl imidazole complex loaded silk is placed in a tube furnace under nitrogen protection for heat treatment for 2 hours at 800 degrees Celsius, to obtain an intermediate;

[0102] S5, using 1 mol / L hydrochloric acid to acid etch the intermediate, etching for 30 minutes, to obtain a flexible transparent carbon fiber mesh.

[0103] Example 6:

[0104] The present example provides a flexible transparent carbon fiber mesh and a preparation method thereof, the preparation method of the flexible transparent carbon fiber mesh comprising the following steps:

[0105] S1, first configure 0.5 mol / L of cobalt nitrate solution 30 mL, marked as A solution, then configure 1 mol / L of 2-methyl imidazole solution 30 mL, marked as B solution;

[0106] S2, the size of 30x30cm 2 silk is first soaked in A solution for 20 minutes, then the silk is soaked in B solution for 10 minutes, then the cobalt-2-methyl imidazole complex will be in situ grown on the surface and pores of the silk;

[0107] S3, the cobalt complex loaded silk is washed with deionized water 3 times, and then placed in a vacuum drying oven at 60 degrees Celsius for drying for 2 hours;

[0108] S4, the cobalt-2-methyl imidazole complex loaded silk after drying is placed in a tube furnace at 800 degrees Celsius under nitrogen protection for 2 hours to obtain an intermediate;

[0109] S5, the intermediate is etched with 1 mol / L hydrochloric acid for 30 minutes to obtain a flexible transparent carbon fiber mesh.

[0110] Example 7:

[0111] The example provides a flexible transparent carbon fiber mesh and a preparation method thereof, the preparation method of the flexible transparent carbon fiber mesh comprising the following steps:

[0112] S1, first configure 0.75 mol / L of cobalt nitrate solution 30 mL, marked as A solution, then configure 1.5 mol / L of 2-methyl imidazole solution 30 mL, marked as B solution;

[0113] S2, the size of 30x30cm 2 silk is first soaked in A solution for 20 minutes, then the silk is soaked in B solution for 10 minutes, then the cobalt-2-methyl imidazole complex will be in situ grown on the surface and pores of the silk;

[0114] S3, the cobalt complex loaded silk is washed with deionized water 3 times, and then placed in a vacuum drying oven at 60 degrees Celsius for drying for 2 hours;

[0115] S4, the cobalt-2-methyl imidazole complex loaded silk after drying is placed in a tube furnace at 800 degrees Celsius under nitrogen protection for 2 hours to obtain an intermediate;

[0116] S5, the intermediate is etched with 1 mol / L hydrochloric acid for 30 minutes to obtain a flexible transparent carbon fiber mesh.

[0117] Example 8:

[0118] The example provides a flexible transparent carbon fiber net and a preparation method thereof, and the preparation method of the flexible transparent carbon fiber net comprises the following steps:

[0119] S1, first, 30 mL of a 1.5 mol / L cobalt nitrate solution is configured and labeled as solution A, and then 30 mL of a 3 mol / L 2-methylimidazole solution is configured and labeled as solution B;

[0120] S2, silk with a size of 30*30 cm 2 is first soaked in the solution A for 20 minutes, and then the silk is soaked in the solution B for 10 minutes, and then a cobalt-2-methylimidazole complex is in-situ grown on the surface and pores of the silk;

[0121] S3, the cobalt complex loaded silk is washed with deionized water for 3 times, and then is placed in a vacuum drying box at 60 degrees Celsius for drying for 2 hours after being laid flat;

[0122] S4, the dried cobalt-2-methylimidazole complex loaded silk is placed in a 800-degree Celsius tube furnace for heat treatment for 2 hours under nitrogen protection, and an intermediate is obtained;

[0123] S5, the intermediate is subjected to acid etching using a 1 mol / L hydrochloric acid for 30 minutes, and a flexible transparent carbon fiber net is obtained.

[0124] Comparative Example 1:

[0125] The example provides a carbon fiber net and a preparation method thereof, and the preparation method of the carbon fiber net comprises the following steps:

[0126] S1, the silk without loading a cobalt-2-methylimidazole complex is washed with deionized water for 3 times, and then is placed in a vacuum drying box at 60 degrees Celsius for drying for 2 hours after being laid flat;

[0127] S2, the dried silk without loading a cobalt-2-methylimidazole complex is placed in a 800-degree Celsius tube furnace for heat treatment for 2 hours under nitrogen protection, and an intermediate is obtained;

[0128] S3, the intermediate is subjected to acid etching using a 1 mol / L hydrochloric acid for 30 minutes, and a carbon fiber net is obtained.

[0129] The electrode material disclosed in the application is characterized in that a porous electrode structure is prepared by in-situ synthesis of a cobalt-imidazole complex and then heat treatment, and for the preparation process of the flexible transparent carbon fiber mesh, an acid etching method is further combined to prepare a porous transparent conductive carbon fiber mesh, which all have excellent electrochemical properties. When they are respectively assembled to prepare a transparent lithium battery and a transparent capacitor, both of them show good electrochemical performance. The electrode material is used as a transparent positive electrode to prepare a lithium battery (battery test: the positive electrode is prepared by using the electrode material, the negative electrode is a metal Li, the electrolyte is a mixed solution of EC ethylene carbonate / DEC diethyl carbonate mixed at a volume ratio of 1:1 and added with LiPF6, the concentration of LiPF6 is 1 mol / L), the initial reversible capacity reaches 1060 mAh·g -1 , and the discharge voltage platform is 0.75 V; the cycle performance of the lithium battery is excellent, and the battery capacity can still reach 1000 mAh·g -1 after 475 cycles at a current density of 4 A·g -1 The flexible transparent carbon fiber mesh is used as an electrode to prepare a capacitor (capacitor test electrolyte: ClNaO4 / PVA hydrogel), and in the cycle stability test, the prepared capacitor can still maintain 78% of the initial capacity after 2000 cycles. The initial surface capacity of the capacitor is as high as 0.227 mF / cm 2 . In the bending test, the capacitor can still work normally and is not damaged after 200 bends. Compared with the traditional preparation method, this manufacturing process has the advantages of simple material preparation, easy raw materials and low cost, and is suitable for large-scale production.

[0130] Figure 1 It is a preparation process diagram of the electrode material of the application. The electrode material of the application is prepared by in-situ synthesis and heat treatment.

[0131] For the flexible transparent carbon fiber mesh, an acid etching step is added to the preparation process of the electrode material, and the flexible transparent carbon fiber mesh and the NaClO4 / PVA hydrogel electrolyte can be constructed into a transparent super capacitor.

[0132] Figure 2 It is the SEM and TEM diagrams of the electrode material obtained after heat treatment in the preparation process of Example 1. As shown in Figure a) of Figure 2 , the electrode material has a carbon fiber mesh structure, and the carbon fiber mesh is interwoven by carbon fibers with a diameter of 100-200 nm, and the fibers are uniformly and orderly distributed. As shown in Figure b) of Figure 2 , the local carbon fiber mesh is enlarged, and it can be obviously observed that the nanoparticles are uniformly distributed.

[0133] Figure 3The XRD pattern of the electrode material obtained after heat treatment in the preparation of Example 1 is completely consistent with the diffraction peak position of metallic cobalt (PDF (standard diffraction card NO.): 00-015-0806), which proves that a large number of metallic cobalt nanoparticles are deposited on the surface of the electrode material.

[0134] Figure 4 The actual picture of the electrode material prepared in Example 1 is placed on the paper with letters, and it can be seen that the letters are clearly blocked through the electrode material in the form of carbon fiber network, which proves that the electrode material has good transparency.

[0135] Figures 5 to 7 The performance chart of the lithium battery prepared based on the electrode material obtained in Example 1;

[0136] wherein, Figure 5 The rate performance of the battery at different current densities, and the specific capacity gradually decreases with the increase of the current density. In the first cycle, the initial reversible capacity reaches 1060 mAh·g -1 With the increase of the rate, the specific capacity of the battery decreases obviously. When the current density returns to 1 A·g -1 , the specific capacity returns to about 1100 mAh·g -1 , which indicates that the battery has good rate recovery ability;

[0137] Figure 6 The cycle performance test chart of the battery, after 475 cycles at a current density of 4 A·g -1 , the battery capacity can still reach 1070 mAh·g -1 , which shows relatively stable cycle performance;

[0138] Figure 7 The battery voltage-specific capacity curve chart, in the first cycle, the charge-discharge curve changes greatly, which indicates that the formation of the solid electrolyte interface (SEI) film may exist in the initial cycle of the battery. The second and third cycle curves are relatively coincident, which indicates that the electrochemical reaction of the battery tends to be stable, showing good reversibility and small polarization phenomenon.

[0139] Figure 8 The TEM and HRTEM pictures of the flexible transparent carbon fiber network prepared in Example 5. The TEM picture is on the left side a), and the HRTEM picture is on the right side b), as shown in the figure, after etching with hydrochloric acid, the carbon fibers form a rich porous structure with a pore size of about 20-30 nm, which can effectively increase the specific surface area of the flexible transparent carbon fiber network, effectively increase the ion adsorption capacity, and improve the capacitance capacity.

[0140] Figure 9 The performance chart of the capacitor (NaClO4 / PVA hydrogel electrolyte) prepared based on the flexible transparent carbon fiber network obtained in Example 5; wherein,Figure 9 Figure a) in FIG. 4 is cyclic voltammograms at different scan rates, the shape and area of the curve change with the increase of scan rate, showing the electrochemical behavior of the capacitor at different scan rates, higher scan rate leads to greater current response, which is due to faster charge / discharge process, indicating that the obtained transparent carbon fiber mesh of the application can be used to prepare capacitors; Figure 9 Figure b) in FIG. 4 is cyclic voltammograms at different potential windows, it can be seen that the current response increases significantly with the increase of potential window, which is in line with the trend, further indicating that the obtained transparent carbon fiber mesh of the application can be used to prepare capacitors; Figure 9 Figure c) in FIG. 4 is cyclic voltammograms at different cycle numbers, the shape and area of the cyclic voltammogram change little with the increase of cycle number, indicating that the capacitor maintains good electrochemical stability and reversibility after multiple cycles; Figure 9 Figure d) in FIG. 4 is the change of the capacitance capacity with the cycle number, the capacitance value gradually decreases from the initial about 221 μF / cm 2 to about 172 μF / cm 2 (2000 cycles), indicating that it has a long service life; Figure 9 Figure e) in FIG. 4 is constant current charge-discharge curves at different currents, higher current leads to shorter charge-discharge time, indicating that the capacitor has fast response ability at high current.

[0141] Figure 10 Figure is the comparison of the capacitance capacity (capacitance current) of the capacitor prepared by the flexible transparent carbon fiber mesh obtained from different examples (Examples 5-8). It can be known that with the increase of the concentration of the soaking solution, the capacitance capacity presents the trend of first increasing and then decreasing, proving the promotion effect of the porous structure and ion adsorption amount on the capacitance capacity. However, excessive deposition of metal cobalt combined with acid etching may cause damage to the structure of carbon fiber, thereby reducing the capacitance capacity.

[0142] Figure 11 Figure is the capacitance capacity change curve of the capacitor prepared based on the carbon fiber mesh obtained from Comparative Example 1. It can be seen that the capacitance capacity gradually decreases from the initial about 39 μF / cm 2 to about 27 μF / cm 2 (2000 cycles). Compared with Example 5, the initial capacitance capacity of the capacitor constructed by the carbon fiber mesh prepared without loading cobalt complex is only about 17% of the supercapacitor constructed by the flexible transparent carbon fiber mesh prepared by loading cobalt complex, and the stability is obviously reduced.

[0143] Figure 12The comparison chart of cyclic voltammograms of the capacitor based on the flexible transparent carbon fiber web obtained from Example 5 after 200 times of bending is shown. It can be seen that after 200 times of bending, the electrochemical performance of the capacitor has no obvious difference.

[0144] The above examples are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable the person skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and principle of the present application shall be covered within the protection scope of the present application.

[0145] The endpoints of the ranges and any values claimed herein are not to be understood as being limited to the exact values recited as endpoints but rather to be understood to include values from the endpoints to the lower or upper value as well as in the endpoint values. For values having a lower and upper endpoint, the endpoints are to be understood to be included. For values having an upper endpoint only, the endpoint is to be understood to be included. For values having a lower endpoint only, the endpoint is to be understood to be included. For values having no stated endpoint, the endpoint is to be understood to be included.

Claims

1. A capacitor comprising a positive electrode, a negative electrode, characterized by, Any one of the positive electrode and the negative electrode comprises a flexible transparent carbon fiber net, and a preparation method of the flexible transparent carbon fiber net comprises: Cobalt nitrate and a compound shown in formula (I) are respectively applied on silk, and a cobalt complex is in-situ grown on the surface and / or pores of the silk to form cobalt complex-loaded silk; wherein the cobalt nitrate is applied on the silk in the form of a cobalt nitrate solution, and the compound shown in formula (I) is applied on the silk in the form of a compound shown in formula (I) solution, the molar concentration of the cobalt nitrate solution is 0.75-1.5 mol / L, and the molar concentration of the compound shown in formula (I) solution is 1.5-3.0 mol / L; In formula (I), R1is C 1-3 alkyl, R2is H or C 1-3 alkyl, n is 1 or 2; The cobalt complex-loaded silk is heat-treated at 700-950 ℃ under a protective atmosphere to obtain an intermediate; Then, the intermediate is subjected to acid etching to obtain the flexible transparent carbon fiber net. The flexible transparent carbon fiber net has pore structures with a size of 20-30 nm.

2. The capacitor of claim 1, wherein The intermediate comprises nitrogen-doped porous carbon and nano-metallic cobalt loaded on the surface of the nitrogen-doped porous carbon and / or encapsulated in the pore structures of the nitrogen-doped porous carbon.

3. The capacitor of claim 2, wherein The nitrogen-doped porous carbon is a carbon fiber net structure formed by interweaving a plurality of carbon fibers.

4. The capacitor of claim 3, wherein The diameter of the carbon fiber is 30-500 nm.

5. The capacitor of claim 4, wherein The diameter of the carbon fiber is 100-200 nm.

6. The capacitor of claim 1, wherein The preparation method of the flexible transparent carbon fiber net further comprises: The cobalt nitrate solution and the compound shown in formula (I) solution are respectively configured; the cobalt nitrate solution and the compound shown in formula (I) solution respectively use water as a solvent; The silk is first soaked in one of the cobalt nitrate solution and the compound shown in formula (I) solution, and then soaked in the other.

7. The capacitor of claim 6, wherein The silk is first soaked in the cobalt nitrate solution for X1 min, and then soaked in the compound shown in formula (I) solution for X2 min, X1:X2=1.5-3:1, X1 is 15-25, and X2 is 5-15.

8. The capacitor of claim 1 wherein, R1 is selected from methyl, ethyl or propyl, R2 is selected from H, methyl, ethyl or propyl; and / or, the material of the silk is mulberry silk; and / or, the preparation method of the flexible transparent carbon fiber net further comprises: before the heat treatment, the cobalt complex-loaded silk is first cleaned with deionized water and subjected to vacuum drying treatment; and / or, the heat treatment is performed at 750-850 ℃.

9. The capacitor of claim 1 wherein, The treatment time of the heat treatment is 1-6 h.

10. The capacitor of claim 9, wherein The treatment time of the heat treatment is 1-3 h.

11. The capacitor of claim 1 wherein, The addition amount of the cobalt nitrate is controlled to be 0.015-0.05 mmol per square centimeter of the silk, and the addition amount of the compound shown in formula (I) is controlled to be 0.03-0.1 mmol per square centimeter of the silk; and / or, the compound shown in formula (I) is a combination of one or more selected from 2-methyl imidazole, 2-ethyl imidazole and 2-propyl imidazole.

12. The capacitor of claim 1 wherein, The acid etching is performed by using hydrochloric acid.

13. The capacitor of claim 12, wherein The molar concentration of the hydrochloric acid is 0.5-3 mol / L.

14. The capacitor of claim 1, 12 or 13, wherein, The etching time of the acid etching is controlled to be 10-60 min.

15. The capacitor of claim 1 wherein, The protective atmosphere is formed by passing nitrogen and / or inert gas.

16. A method of making a flexible transparent carbon fiber web, characterized by, The preparation method comprises: Cobalt nitrate and a compound shown in formula (I) are respectively applied on silk, and a cobalt complex is in-situ grown on the surface and / or pores of the silk to form cobalt complex-loaded silk; wherein the cobalt nitrate is applied on the silk in the form of a cobalt nitrate solution, and the compound shown in formula (I) is applied on the silk in the form of a compound shown in formula (I) solution, the molar concentration of the cobalt nitrate solution is 0.75-1.5 mol / L, and the molar concentration of the compound shown in formula (I) solution is 1.5-3.0 mol / L; In formula (I), R1is C 1-3 alkyl, R2is H or C 1-3 alkyl, n is 1 or 2; The cobalt complex-loaded silk is heat-treated at 700-950 DEG C under a protective atmosphere to obtain an intermediate; Then, the intermediate is subjected to acid etching to obtain the flexible transparent carbon fiber net.

17. An electronic device, comprising: The electronic device has the capacitor as claimed in any one of claims 1-15, or the flexible transparent carbon fiber net prepared by the preparation method of the flexible transparent carbon fiber net as claimed in claim 16.

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