CN113327775B - A kind of preparation method and electrode material of potassium ion micro-hybrid capacitor - Google Patents

Abstract

The present invention relates to a preparation method and electrode material of a potassium ion miniature hybrid capacitor. In this method, the active material was sprayed on polyethylene terephthalate (PET) with the aid of a mold using an air spray gun, and a micro flexible interdigital electrode with multidirectional ion transport channels was constructed on the PET transparent flexible substrate. After the electrode is vacuum-dried, the microporous polymer electrolyte is coated on the surface of the electrode, and finally the electrolyte is dropped into a vacuum bag and packaged to obtain a flexible potassium ion micro-hybrid capacitor. The electrode material is a multi-dimensional topological structure material in which part of potassium titanate is grown between graphite layers; in the preparation method, potassium hydroxide is used as potassium source, and nano-titanium dioxide is used as titanium source. Hydrothermal compound at temperature. The material obtained by the invention effectively solves the problems of low electrical conductivity, low capacity and poor rate performance of potassium titanate material.

Description

A kind of preparation method and electrode material of potassium ion micro-hybrid capacitor

technical field

The patent of the invention belongs to the field of high specific energy supercapacitors, and specifically relates to an electrode material of a potassium ion micro-hybrid capacitor and a preparation method and application thereof.

Background technique

With the continuous development of society, people's functional requirements for electronic products are also constantly improving, and electronic products have also ushered in a period of rapid development. For example, smartphones, tablet computers, intelligent robots, electronic watches and various wearable devices are constantly developing towards miniaturization and flexibility. However, these self-powered electronic products, which are gradually becoming miniaturized and flexible, also face the problem of power supply. Therefore, electrochemical energy storage devices of various scales have become key power sources for miniaturized and flexible smart and integrated electronic products, such as self-powered microsystems such as human sensors and microrobots. At present, various advanced energy storage devices are mainly based on lithium-ion batteries and capacitors, but their limited lithium resources have also stimulated people's enthusiasm to develop other energy storage devices. Potassium ion has become a research hotspot because of its abundant resources and its redox potential close to that of lithium ion.

However, potassium ion energy storage devices also face some challenges. For example, the size of potassium ions (0.138 nm) is larger than that of lithium ions (0.076 nm), which makes the kinetics of potassium ion insertion/extraction in the electrode material slow, resulting in low capacity of the electrode material. and poor cycling stability and rate capability. Ti-based compounds, such as lithium titanate (Li ₄ Ti ₅ O ₁₂ , LTO), are ideal candidates for safe and stable operation of negative electrodes in lithium-ion batteries, which are currently used in large-scale commercial lithium-ion batteries and lithium-ion hybrid capacitors. Therefore, potassium titanate (K ₂ Ti _n O _2n+1 , KTO) is also expected to be well applied in the field of potassium ion batteries or hybrid capacitors. The KTO ternary anode can provide an efficient K ⁺ intercalation channel, and the insertion/deintercalation process has little effect on its basic structure and performance, so it has good cycling stability. However, its low electronic conductivity inhibits its potassium storage performance and limits the development of potassium ion energy storage devices. Two titanium-based compounds, K ₂ Ti ₄ O ₉ and K ₂ Ti ₈ O ₁₇ , were recently reported and applied in potassium-ion energy storage devices, however, they have only very limited cycling and rate capabilities. In order to improve the potassium storage performance of KTO, it is an effective technical route to control its composition, microstructure and composite with highly conductive carbon materials.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a potassium ion micro-hybrid capacitor and its preparation method and electrode material in view of the problem of limited raw material resources of lithium ion energy storage devices in the current technology. The electrode material is a multi-dimensional topological structure material in which a part of potassium titanate is grown between graphite layers; in the preparation method, potassium hydroxide is used as potassium source, and nano-titanium dioxide is used as titanium source. Hydrothermal composite at temperature, the obtained material effectively solves the problems of low electrical conductivity, low capacity and poor rate performance of potassium titanate material. In terms of application, the present invention abandons the traditional sandwich-type flexible capacitor, uses an air spray gun to spray the active material on polyethylene terephthalate (PET) with the aid of a mold, and builds a transparent flexible Miniature flexible interdigital electrodes for multidirectional ion transport channels. After the electrode is vacuum dried, the microporous polymer electrolyte is coated on the surface of the electrode, and then the organic solvent in the electrolyte is dried. The electrode is put into a vacuum bag in an argon gas glove box, and the electrolyte is added dropwise and packaged to obtain a flexible potassium ion microarray. Hybrid capacitors. By controlling the spraying amount of active material, the capacitor can obtain different area specific capacity.

In order to achieve the above objects, the present invention adopts the following technical solutions.

A preparation method of potassium ion miniature hybrid capacitor, the method comprises the following steps:

(1) Add polyethylene oxide and PVDF-HFP into an organic solvent, and stir at 40-80° C. for 18-24 hours to obtain a microporous polymer electrolyte;

Among them, add 20-50mg of polyethylene oxide and 800-1000mg of PVDF-HFP per 6-19ml of organic solvent;

(2) Add potassium titanate@graphite composite to the deionized water as the negative electrode active material of the capacitor, prepare a mixed solution with a concentration of 0.5-1 mg/ml, and then add a certain amount of alkalized MXene solution, conductive carbon black ( CB) as a conductive agent and carboxymethyl cellulose (CMC) as a binder to prepare a negative electrode material mixture;

Among them, the mass ratio of potassium titanate@graphite composite, alkalized MXene, CB, CMC is (14:2-5:0.5-2.5:0.5-3), and the concentration of alkalized MXene solution is 4-6mg/ml;

In addition, activated carbon (AC) was added to deionized water to prepare a mixed solution with a concentration of 0.5-1 mg/ml, which was used as the positive electrode active material of the capacitor, and then alkalized MXene solution, conductive carbon black (CB) and carboxymethyl fiber were added to it. Element (CMC) was used to prepare a positive electrode material mixture; the mass ratio of AC, alkalized MXene, CB, and CMC was (14:2-5:0.5-2.5:0.5-3), and the concentration of the alkalized MXene solution was 4-6mg/ml;

(3) Fix the metal mold of the interdigital electrode on the PET, then block the positive electrode of the metal mold with a baffle, spray 0.05-0.1 ml of silver nanowire solution on the PET as a current collector with a spray gun, and then use the prepared negative electrode The mixed solution was sprayed on the silver nanowires to construct the negative part of the interdigital electrode; the active material (potassium titanate@graphite composite) of the negative electrode had a dressing density of 4-480 μg cm ^-2 ;

Then remove the baffle fixed on the positive electrode of the mold and the negative electrode fixed on the metal mold, spray 0.05-0.1 ml of silver nanowire solution on the PET as a current collector with a spray gun, and then spray the prepared positive mixed solution on the metal mold. On the silver nanowires, the positive electrode part of the interdigital electrode is constructed, and the active material (AC) dressing density of the positive electrode is 6-500 μg cm ^-2 ;

(4) Stick aluminum tabs and nickel tabs on the positive and negative electrode parts of the interdigital electrode prepared in the previous step with copper paste, and after drying at 50-100 °C, the prepared microporous polymer electrolyte is coated On the electrode, it is dried at 50-110 °C, and finally the dried electrode is put into a vacuum bag in an argon glove box, and the electrolyte is added dropwise and packaged.

The organic solvent in the described step (1) is a mixed solution in which the volume ratio of acetone to alcohol is (4-5):1.

The drying method in the step (4) is vacuum drying.

An electrode material of potassium ion battery potassium titanate@graphite composite, the material is composed of one-dimensional nanowire-shaped potassium titanate and quasi-two-dimensional nanographite sheets, wherein the mass ratio of potassium titanate to graphite sheets is (4 -5): 1; The interconnected nanowire-like potassium titanate with a diameter of 7.5-8.0 nm is uniformly distributed between the two-dimensional graphite nanosheets, forming a multi-dimensional hierarchical structure; at the same time, the specific surface area of the material is as high as 168.9 m ² g ^-1 , the corresponding pore sizes are mainly distributed in 5-30 nm, and there are some micropores and macropores, showing the packing structure of one-dimensional and two-dimensional composites.

A method for preparing an electrode material potassium titanate@graphite composite for a potassium ion battery, comprising the following steps:

Adding titanium source to potassium source solution, then adding graphite, hydrothermal reaction at 100-250℃ for 20-50h, nanowire-shaped potassium titanate@graphite composite material was obtained;

Wherein, the potassium source is potassium hydroxide, and the titanium source is nano-titanium dioxide; the mass ratio of potassium hydroxide, titanium dioxide and graphite is (200-400): (2-3): 1, and the concentration of the potassium hydroxide aqueous solution is (9- 11)mol/L;

The preparation method of the two-dimensional alkalized MXene comprises the following steps:

Lithium fluoride is added to the hydrochloric acid, and the etching solution is obtained after mixing, adding Ti ₃ ALC ₂ to it, etching at 30-40 ° C for 20-35 h, and then centrifuging with deionized water at a speed of 3000-8000 r/min for 7 - 9 times to remove the acidic etching solution, then dissolve the precipitate after centrifugation in water, dissolve the precipitate obtained per 10 ml of hydrochloric acid in 50-80 mL of water, and ultrasonicate the ice for 30-60 min; Centrifuge at -4000r/min for 5-10min, take out the upper layer liquid, which is the monolayer MXene solution;

Then according to the ratio of adding 10-30g potassium hydroxide to each 60ml MXene solution, the single-layer MXene was alkalized at room temperature for 20-40h, and then the potassium hydroxide was removed by centrifugation at a rotational speed of 4000-8000r/min to a pH of 7. Add deionized water to the centrifugal precipitation to obtain an alkalized MXene solution with a porous structure with a concentration of 4-6 mg/ml;

The concentration of the hydrochloric acid is (10-15) M, and 800-2000 mg of lithium fluoride is added to every 10 ml of hydrochloric acid; 500-1200 mg of Ti ₃ ALC ₂ is added to every 10 mL of etching solution;

The beneficial effects of the present invention are:

(1) The present invention provides a potassium titanate@graphite electrode material. By hydrothermally compounding nanowire-shaped potassium titanate and flake graphite, it not only eliminates the electrochemical reaction caused by the two-dimensional stacking effect after pure graphite spraying The problem of extremely poor performance is effectively solved, and the problems of low conductivity, low capacity and poor rate performance of potassium titanate materials are effectively solved.

(2) The present invention uses a two-dimensional MXene material with excellent electrical conductivity as a conductive agent. After adding it to the negative electrode and the positive electrode to prepare an interdigitated electrode in a certain proportion, it can act as a bridge, and the negative electrode titanium The potassium oxide@graphite electrode material is connected with the active carbon of the positive electrode active material, which provides a good channel for electron transport and greatly improves the conductivity of the interdigital electrode.

(3) In the present invention, the two-dimensional MXene material is alkalized in a potassium hydroxide solution of a certain concentration for a certain period of time, so that a certain amount of nanopores are generated on the two-dimensional surface. It will hinder the diffusion of ions in the electrode, and greatly reduce its hindering effect on the electrochemical performance of the electrode active material.

(4) The present invention abandons the traditional sandwich structure capacitor, and adopts interdigital electrodes with multidirectional fast ion transmission channels. Since the interdigital structure has a distance of 500 μm between each positive and negative interdigital fingers, the micro The capacitor electrode has a very high areal specific capacity of 12.5mF cm ^-2 .

(5) Compared with the traditional water-based capacitor whose maximum voltage is 1.5V, the capacitor of the present invention can be charged up to 3V due to the use of interdigitated electrodes, potassium titanate@graphite electrode material and semi-solid organic electrolyte. And it has good integration performance, if two capacitors are connected in series, a voltage of up to 6V can be obtained.

Description of drawings

Fig. 1 is the XRD pattern of the potassium titanate graphite composite in embodiment 1;

Fig. 2 is the scanning electron microscope (SEM) figure of the potassium titanate graphite composite in embodiment 1;

Figure 3 is a photo of the assembled microcapacitor;

4 is a time-voltage diagram under different current densities of Example 1;

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and the preferred embodiments.

The purpose of the present invention is to manufacture a flexible microcapacitor with high areal specific capacity and high energy power density. The combination of potassium titanate and graphite by hydrothermal method reduces the agglomeration effect of potassium titanate and the tiling effect of graphite, which not only improves the specific capacity of the material, but also improves the rate performance and cycle stability of the potassium titanate material. sex. Asymmetric microcapacitors were assembled on PET flexible substrates by mixing activated carbon with a certain proportion of alkalized porous MXene, CMC and CB with a certain proportion of activated carbon as the negative electrode. The specific method includes: (1) Preparation of alkalized MXene solution: take 800-2000 mg of lithium fluoride, add 10 ml (10-15) M hydrochloric acid, stir for 5-10 min, add 500-1200 mg of Ti 3 ALC 2 powder, and add 500-1200 mg of Ti ₃ ALC ₂ powder at 30 Stir at -40°C for 20-35h, then centrifuge it with deionized water to a pH of about 7, then dissolve the centrifuged precipitate in 60-100mL of deionized water, and sonicate in ice for 30-60min. The sonicated solution was centrifuged at 2000-4000 r/min for 5-10 min, and the upper layer was taken out to obtain the MXene solution. Add 10-30 g of potassium hydroxide to the dispersed MXene solution, and after stirring for 20-40 h, the potassium hydroxide in the solution is removed by centrifugation to obtain alkalized MXene. (2) Preparation of potassium titanate@graphite composite material: 10-20mg of graphite, 30-60mg of nano-titanium dioxide and 5-8g of potassium hydroxide were added to deionized water to obtain a mixed solution, stirred for 200-300min and then transferred In a high-pressure reaction axe, react at 100-250 °C for 20-50 h to obtain potassium titanate@graphite composite, which is then washed with deionized water until the pH is neutral, and then dried in an oven at 70-100 °C Potassium titanate@graphite composite powder was obtained in 12-24h. (3) Preparation of microporous polymer electrolyte material: take 20-50 mg of polyethylene oxide and 800-1000 mg of PVDF-HFP, add 5-15 ml of acetone and 1-4 ml of absolute ethanol, and stir at 40-80 ° C for 18 -24h to obtain microporous polymer electrolyte. (4) Preparation of negative electrode material solution: take deionized water as solvent, add a certain amount of potassium titanate@graphite composite to it as the negative electrode active material of capacitor, and then add a certain amount of alkalized MXene solution and conductive carbon black to it (BC) and CMC to prepare a negative electrode material solution. (5) Preparation of positive electrode material solution: using deionized water as a solvent, adding a certain amount of activated carbon as the negative electrode active material of the capacitor, and then adding a certain amount of alkalized MXene, conductive carbon black (BC) and CMC to it to prepare The positive electrode material solution is taken out. (6) Preparation of interdigital electrode: fix the metal mold of the interdigital electrode on the PET, then fix the baffle of the interdigital electrode mold to the position of the positive electrode of the metal mold, spray a certain thickness of silver nanowires with a spray gun, and then prepare the The good negative electrode mixture was sprayed on the silver nanowires to construct the negative part of the interdigital electrode. Then, the baffle plate fixed on the positive electrode of the metal mold was removed from the negative electrode part fixed on the metal mold, and the positive electrode part of the interdigital electrode was constructed in the same steps as the negative electrode. (7) Assembly of the microcapacitor: The aluminum tabs and the nickel tabs are respectively attached to the positive and negative parts of the interdigital electrodes prepared in the previous step with copper paste, and after vacuum drying at 50-100 ° C, the prepared The microporous polymer electrolyte is coated on the electrode, and then dried in a vacuum at 50-110 °C, and then the electrode is put into a vacuum bag in an argon glove box, and the electrolyte is added dropwise and packaged.

In order to better understand the invention, it will be described in detail below with reference to 4 embodiments. It should be recognized, however, that these embodiments are merely illustrative of the present invention, rather than limiting. The compounds or reagents used in the following examples are commercially available, or can be prepared by conventional methods known to those skilled in the art; the experimental instruments used are commercially available.

Example 1:

Step 1: Take 1600mg of lithium fluoride and add it to 10ml (12M) dilute hydrochloric acid, stir for 5min, add 1000mg of Ti ₃ ALC ₂ powder with a particle size of 300 molybdenum, and stir at 35°C for 24 hours to remove the AL layer in the Ti ₃ ALC ₂ powder. It was etched away, then centrifuged and washed with deionized water at 3500 r/min until the pH was about 7, and then the centrifuged precipitate was dissolved in 60 mL of deionized water, and sonicated in an ice bath for 60 min. The sonicated solution was centrifuged at 3500 r/min for 5 min, and the upper layer was taken out to obtain the monolayer MXene solution.

Add 20.16g of potassium hydroxide to the dispersed MXene solution, stir at room temperature for 36h (the single-layer MXene is alkalized at room temperature), and then centrifuge at 4500r/min to PH=7 to remove the potassium hydroxide , and then add a certain amount of deionized water to the centrifugal precipitation to obtain an alkalized MXene solution with a porous structure with a concentration of 5 mg/ml.

20mg of graphite and 50mg of nano-titanium dioxide were added to 10ml (10M) of potassium hydroxide aqueous solution to obtain a mixed solution, stirred for 250min and then transferred to a high pressure reaction axe, and reacted at 200°C for 48h to obtain potassium titanate@graphite composite , and then centrifugally washed with deionized water at 8000 r/min until the pH is neutral, and then dried in an oven at 80 °C for 12 h to obtain potassium titanate@graphite composite powder.

Take 40 mg of polyethylene oxide and 800 mg of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), add 10 ml of acetone and 2 ml of absolute ethanol, and stir at 70 °C for 20 h to obtain a microporous polymer electrolyte.

Step 2: Take 1.8 mg of potassium titanate@graphite composite, disperse it in 4 ml of deionized water, and then add 0.103 ml of alkalized MXene dispersion with a concentration of 5 mg/ml, 0.129 mg of CB and 0.129 mg of CMC to it , and mechanically stirred for 5h to obtain a negative electrode material mixture.

Step 3: Take 2.7 mg of activated carbon, disperse it in 6 ml of deionized water, add 0.155 ml of alkalized MXene dispersion liquid with a concentration of 5 mg/ml, 0.194 mg of CB and 0.194 mg of CMC, and stir mechanically for 5 hours to obtain Positive electrode material mixture.

Step 4: After cleaning the PET with water, place it in a UV cleaning machine for 2 minutes.

Step 5: Take out the cleaned PET and glue it to the metal interdigital mold with a small amount of solid.

Step 6: Use the interdigital electrode baffle to cover the positive part of the metal interdigitated mold.

Step 7: Put 20 μL of silver nanowires in the spray gun, and spray it on the negative part of the interdigital electrode at a speed of 1 ml/h. (Area is 4.16cm ² )

Step 8: Put the mixed solution prepared in Step 1 in a spray gun, and spray it on the silver nanowires at a speed of 2ml/h.

Step 9: After spraying, remove the interdigital baffle of the negative electrode, and use the baffle to cover the positive part of the interdigitated metal template in the same way.

Step 10: Put 20 μL of silver nanowires in a spray gun, and spray it on the positive part of the interdigital electrode (same area as the negative electrode) at a speed of 1 ml/h.

Step 11: Put the mixed solution prepared in the second step in the spray gun, and spray it on the silver nanowires at a speed of 2ml/h.

Step 12: After spraying, remove the interdigital baffle of the positive electrode, and then remove the interdigital template to obtain the interdigital electrode.

Step 13: Use copper paste to stick aluminum tabs and nickel tabs to the positive and negative electrodes of the electrodes.

Step fourteen: place the prepared interdigital electrode in a vacuum oven, and dry it at a temperature of 80° C. for 15 hours to completely remove the residual water in the electrode.

Step 15: Use a dropper to drop two drops of the prepared microporous polymer electrolyte on the electrode, then spread it evenly, and place the microporous polymer-coated interdigital electrode in a vacuum oven at 80°C. Drying at high temperature for 12 h to completely remove the residual organic solvent in the electrode.

Step 16: In an argon glove box, seal the dried electrodes with a small vacuum sealing machine.

Step 17: Open a small opening on the side of the vacuum bag that does not contain the electrode ears, and then inject the potassium ion electrolyte into the electrode.

Step 18: After injecting electrolyte (0.8M KPF ₆ inEC:DEC=1:1 Vol%) and soaking for 6 hours, the excess electrolyte was extracted and sealed with a vacuum sealing machine to obtain a flexible potassium titanate microcapacitor.

Example 2:

The only difference between Example 2 and Example 1 is that the positive and negative electrode active material solutions of the interdigital electrodes are used in different amounts, which are 60 μL of the prepared positive mixed solution and 90 μL of the prepared negative mixed solution.

Example 3:

The difference between Example 3 and Example 1 is only that the positive and negative electrode active material solutions of the interdigital electrodes are used in different amounts, which are 40 μL of the prepared positive mixed solution and 60 μL of the prepared negative mixed solution.

Example 4:

The only difference between Example 4 and Example 1 is that the positive and negative electrode active material solutions of the interdigital electrodes are used in different amounts, which are 20 μL of the prepared positive mixed solution and 30 μL of the prepared negative mixed solution.

Electrochemical performance tests were carried out on the capacitors of each embodiment (using a Princeton electrochemical workstation, the voltage range was selected as 0.01-3V, and the current density was 0.005mA cm ^-2 -0.2mA cm ^-2 , and the results are shown in Table 1.

Table 1. Capacitor capacity test results of each embodiment

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Matters not addressed in the present invention are known in the art.

Claims (4)

1. a preparation method of potassium ion miniature hybrid capacitor is characterized in that the method comprises the following steps: (1) Add polyethylene oxide and PVDF-HFP into an organic solvent, and stir at 40-80 °C for 18-24 h to obtain a microporous polymer electrolyte; Among them, add 20-50 mg of polyethylene oxide and 800-1000 mg of PVDF-HFP per 5-15 ml of organic solvent; (2) Potassium titanate@graphite composite was added to deionized water as the negative electrode active material of the capacitor, and the concentration was 0.4- 1 mg/ml mixed solution, and then add a certain amount of alkalized MXene solution, conductive carbon black as a conductive agent, and carboxymethyl cellulose as a binder to prepare a negative electrode material mixed solution; Among them, the mass ratio of potassium titanate@graphite composite, alkalized MXene, conductive carbon black, and carboxymethyl cellulose is (14:2-5:0.5-2.5:0.5-3), and the concentration of alkalized MXene solution is 4-6 mg/ml; In addition, activated carbon was added to deionized water to prepare a mixed solution with a concentration of 0.4-1 mg/ml, which was used as the positive electrode active material of the capacitor, and then alkalized MXene solution, conductive carbon black and carboxymethyl cellulose were added to it, and mixed to obtain Positive electrode material mixture; the mass ratio of activated carbon, alkalized MXene, conductive carbon black, and carboxymethyl cellulose is (14:2-5:0.5-2.5:0.5-3), and the concentration of alkalized MXene solution is 4 -6 mg/ml; (3) Fix the metal mold of the interdigital electrode on the PET, then block the positive electrode of the metal mold with a baffle, spray 4-15 μL cm ^-2 of silver nanowire solution on the PET as a current collector with a spray gun, and then prepare the The good negative electrode mixture was sprayed on the silver nanowires to construct the negative electrode part of the interdigital electrode; the active material dressing density of the negative electrode was 4-480 μg cm ^-2 ; Then remove the baffle fixed on the positive electrode of the mold and remove the negative electrode fixed on the metal mold, spray 4-15 μL cm ^-2 of silver nanowire solution on the PET as a current collector with a spray gun, and then mix the prepared positive electrode. The liquid was sprayed on the silver nanowires to construct the positive electrode part of the interdigital electrode, wherein the active material dressing density of the positive electrode was 6-500 μg cm ^-2 ; (4) Stick aluminum tabs and nickel tabs on the positive and negative parts of the interdigital electrodes prepared in the previous step with copper paste, and after drying at 50-100 °C, coat the prepared microporous polymer electrolyte with On the electrode, it is dried at 50-110 °C, and finally the dried electrode is put into a vacuum bag in an argon glove box, and the electrolyte is added dropwise and packaged. 2 . The method for preparing a potassium ion micro-hybrid capacitor according to claim 1 , wherein the organic solvent in the step (1) is a mixed solution with a volume ratio of acetone to alcohol of (4-5):1. 3 . 3. The method for preparing a potassium ion micro-hybrid capacitor according to claim 1, wherein the drying method in the step (4) is vacuum drying. 4. the preparation method of potassium ion micro-hybrid capacitor as claimed in claim 1, is characterized in that the preparation method of described alkalized MXene, comprises the following steps: Lithium fluoride is added to hydrochloric acid, mixed to obtain an etching solution, Ti ₃ AlC ₂ is added to it, etched at 30-40 ° C for 20-35 h, and then centrifuged with deionized water at a speed of 3000-8000 r/min Wash until neutral, then dissolve the centrifuged precipitate in water, dissolve the precipitate obtained per 10 ml of hydrochloric acid in 50-80 mL of water, and sonicate in ice bath for 30-60 min; sonicate the solution at 2000-4000 r After centrifuging at a speed of /min for 5-10 min, take out the upper layer liquid, which is the monolayer MXene solution; Then add 10-30 g of potassium hydroxide to each 60 ml of MXene solution, stir for 20-40 h, then centrifuge at 4000-8000 r/min to pH 7, and add deionized water to the centrifugal sediment to obtain an alkalized MXene solution with a porous structure with a concentration of 4-6 mg/ml; The concentration of the hydrochloric acid is (10-15) M, and 800-2000 mg of lithium fluoride is added to every 10 ml of hydrochloric acid; and 500-1200 mg of Ti ₃ AlC ₂ is added to every 10 mL of etching solution.

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