CN115020120B - A composite staggered stacked intercalation structure graphene-bismuthene airgel, preparation method and application - Google Patents

Abstract

The invention discloses a composite graphene-bismuth alkene aerogel with a staggered stacking intercalation structure, a preparation method and application thereof. According to the invention, the bismuth alkene thin sheet is inserted into the graphene thin sheet, so that a staggered stacking intercalation structure is realized, wherein 80-100 tiny units exist on each unit centimeter thickness, and each tiny unit is formed by stacking 800-900 layers of single-layer graphene and 80-100 layers of stacked single-layer bismuth alkene in a staggered manner. The graphene-bismuth alkene aerogel has high elastic compressibility, and has 0.326kPa within the stress range of 1.5-4.5 kPa ^‑1 Is high in sensitivity; the strain-electricity response and ultrasensitive detection limit are stable, and the low voltage is effectively detected; has super capacitance characteristic of 400 W.Kg ^‑1 45.55Wh Kg is provided ^‑1 The cycle stability reached 89.24% even after 3600 charge-discharge cycles.

Description

A composite staggered stacked intercalation structure graphene-bismuthene airgel and its preparation method and applications

technical field

The invention relates to a composite staggered stacked intercalation structure graphene-bismuthene airgel, a preparation method thereof and an application in a supercapacitive pressure sensor, belonging to the field of electronic material devices.

Background technique

Graphene airgel has good electrical conductivity and high strength, and has attracted much attention in the fields of energy storage, energy absorption, and sensing. Its preparation methods include hydrothermal method, freeze casting, 3D (three-dimensional) printing, chemical bonding and template method, among which hydrothermal method and freeze casting are the most simple and easy. Bismuth has a large reserve on the earth, and its abundance is comparable to that of silver. It is widely used and has high ion conductivity. It is a very important optical material, electronic material, superconducting material, etc. Capacitive pressure sensors have the advantages of fast response, low cost, high sensitivity, and small hysteresis.

Existing Chinese patent "a flexible capacitive pressure sensor based on graphene and its preparation method" (publication number CN112781757A), the sensor is provided with two parallel graphene electrode layers up and down, the inside of the electrode layer is bonded by CC bonds, the density is 13.21mg cm ^-3 , a porous elastomer is arranged between the two graphene electrode layers, and silver paste wires are drawn out of the graphene electrode layers to form peripheral leads. The sensitivity of the sensor is 1.1kPa ^-1 , the error of the pressure result is large, and the stress sensitivity is low.

In the existing literature, M.Ciszewski et al. [Ionics 21,557-563(2014).] mentioned that the composite material of bismuth oxalate hydrate and graphene oxide was converted into bismuth oxide by thermal decomposition in a muffle furnace and graphene oxide was reduced. When the current density of the composite material was 0.2A g ^-1 , the specific capacitance reached 94F g ^-1 . Using cyclic voltammetry, the specific capacitance is 55F·g ^-1 when the scanning rate is 5mV·s ^-1 within the potential range of 0-1V. After 3000 cycles, the material exhibits long-term cycling stability with a specific capacitance of 90%. However, this composite material does not realize the combination of bismuth and graphene, but mixes Bi ₂ O ₃ in graphene oxide, which does not fully reflect the advantages and characteristics of bismuth intercalation in graphene airgel.

Contents of the invention

Aiming at the problems existing in the above-mentioned prior art, the present invention provides a composite staggered stacked intercalation structure graphene-bismuthene airgel. The composite aerogel is a bismuthene layer inserted between graphene layered structures. The synergistic effect of bismuthene and graphene staggered stacked intercalation structure realizes the design and construction of ion/electron dual transport channels in the layered porous airgel framework. This structure facilitates electrolyte penetration and ensures electron transfer between layers, effectively increasing the mass capacitance. In addition, conductive bismuth nanosheets coated on reduced graphene can serve as the backbone to construct additional electron transport channels and generate additional electrochemically active sites to enhance interlayer conductivity, thereby ensuring interlayer electron transport.

The present invention also provides the preparation method of the above-mentioned composite graphene-bismuthene staggered intercalation structure airgel and its application in supercapacitive pressure sensors, including the preparation of composite staggered stacking intercalation structure graphene-bismuthene hydrogel, the preparation of composite staggered stacking intercalation structure graphene-bismuthene aerogel and its application in the field of supercapacitive pressure sensors.

Preferably, the preparation steps of the above-mentioned composite staggered intercalation structure bismuthene-graphene airgel are as follows:

1) Preparation of bismuthene: Mix bismuth powder and (NH ₄ ) ₂ S ₂ O ₈ in a flask; then, add concentrated H ₂ SO ₄ and H ₂ O ₂ to the above mixed solution, seal it at room temperature, and then wash with ethanol to remove residual H ₂ SO ₄ ; then ultrasonicate in a closed environment. Finally, the mixture was filtered to remove unexfoliated bismuth powder, and 0.014-0.017 g·mL ^-1 bismuthene was obtained from the supernatant.

2) Preparation of composite staggered stacked intercalation structure graphene-bismuthene hydrogel: first, graphene oxide was put into a mixed solution of deionized water and ammonia solution, and ultrasonically treated. The graphene solution is then mixed with the bismuthene solution. The precursor solution was sealed in a 10 mL Teflon-lined autoclave at a temperature of 120 °C for 12-14 h. Subsequently, the hydrogel was dialyzed against a mixture of CH ₃ CH ₂ OH/H ₂ O (1:100, V:V) and cooled to room temperature. A composite staggered stacked intercalation structure graphene-bismuthene hydrogel was prepared. The ammonia solution is commonly used ammonia water with a concentration of 25-28%.

3) Preparation of composite staggered stacked intercalation structure graphene-bismuthene aerogel: freeze the hydrogel obtained in step 2) in a refrigerator, and then freeze-dry it in a freeze-drying box to obtain a composite staggered stacked intercalation structure graphene-bismuthene aerogel.

Preferably, the preparation steps of the supercapacitive pressure sensor described above are as follows:

1) First mix PVA powder with concentrated H ₂ SO ₄ , then add deionized water, stir in a water bath and keep heating at 80-85°C to dissolve completely, forming a gel electrolyte.

2) The composite graphene-bismuthene staggered intercalation structure airgel is fixed on the titanium electrode through conductive silver paste, and dried to obtain a composite staggered stacking intercalation structure graphene-bismuthene airgel electrode, that is, graphene-bismuthene airgel/Ti electrode. Two pieces of graphene-bismuthene airgel/Ti electrodes as negative and positive electrodes were soaked in the prepared gel electrolyte respectively. A polypropylene diaphragm paper with a size of ^0.7-1.0cm2 is sandwiched between the two electrodes to realize a symmetrical all-solid-state supercapacitor, that is, a supercapacitive pressure sensor.

The pressure sensor of the present invention has a sensitivity of 0.326 kPa ^-1 within the stress range of 1.5 to 4.5 kPa, and can provide a rapid current response to external pressure changes; after 1000 cycles of pressure, the relative change of capacitance still retains 87% of the original value, has high stress stability, and can sense small changes in strain and pressure.

Principle of the present invention is:

When preparing bismuthene: mix bismuth powder and (NH ₄ ) ₂ S ₂ O ₈ in a flask to obtain a uniform dispersion; then, add concentrated H ₂ SO ₄ and H ₂ O ₂ to the above mixed solution, use its strong oxidative property to peel off the bismuth powder, seal it in a closed environment, and then wash with ethanol to remove residual H ₂ SO ₄ , mix the obtained powder with deionized water, and mix it thoroughly by ultrasonic in a sealed environment. Finally, the mixture was filtered to remove unexfoliated bismuth powder, and bismuthene was obtained from the supernatant. Bismuthene is mainly composed of the metal element bismuth. Bismuthene is inserted into the interlayer structure of graphene, which can effectively enhance the interaction between graphene sheets, form electron/ion dual transport channels, facilitate the penetration of electrolytes, slow down the decline in interlayer conductivity, ensure the transmission of interlayer electrons, and provide a higher accessible surface area. This feature helps electrolyte ions quickly penetrate and enter the inner surface of the electrode material.

When preparing a composite staggered stacked intercalation structure graphene-bismuthene hydrogel: first, put graphene oxide into a mixed solution of deionized water and ammonia solution, and ultrasonically disperse it to promote solid-liquid reaction. Then the precursor solution was dispersed and mixed with graphene oxide solution, regenerated bismuthene solution and deionized water, so that the particle size of the dispersed phase was reduced, the interphase interface was increased, and the particles were uniformly dispersed; the precursor solution was heated and reacted in a polytetrafluoroethylene-lined high-pressure reactor, and then cooled to room temperature to obtain a hydrogel. Then, the hydrogel was dialyzed in a mixture of CH ₃ CH ₂ OH/H ₂ O (1:100, V:V) to remove impurities and obtain a composite intercalated intercalated graphite structure ene-bismuthene hydrogels. When the hydrogel is prepared by the hydrothermal method, a bismuthene layer is inserted between the layered structures of graphene. Through observation and density calculation of the electron microscope image of the gel, there are 80-100 micro-units per unit centimeter thickness as shown in Figure 1. Each micro-unit is composed of 800-900 layers of single-layer graphene and 80-100 layers of bismuthene. The bismuthene layer and the graphene layer are formed by strong hydrogen bonds and C-Bi bonds. Design and construction of ion/electron dual transport channels in layer-structured airgel frameworks. The bismuth-based graphene framework exhibits cross-linked hierarchical structures with different sizes ranging from hundreds of nanometers to several micrometers, which facilitate electrolyte penetration and ensure electron transfer between layers, effectively increasing the mass capacitance. In addition, conductive bismuth nanosheets coated on reduced graphene can serve as the backbone to construct additional electron transport channels and generate additional electrochemically active sites to enhance interlayer conductivity, thereby ensuring interlayer electron transport. It can also be used as a nano-anchor to enhance the bonding strength between multilayer graphene sheets, thereby enhancing the mechanical properties of the gel; at the same time, an additional electron transport channel is constructed between the graphene sheets to ensure interlayer electron transport, thereby alleviating the decrease in interlayer conductivity caused by intercalation of the interlayer space. At the same time, this structure can be used as a pseudocapacitive active material.

When preparing the composite staggered stacked intercalation structure graphene-bismuthene aerogel, dialyze the obtained composite staggered stacked intercalation structure graphene hydrogel in a mixed solution of ethanol and water, separate and purify to remove the floating gel, put it in the refrigerator to freeze, protect the hydrogel carrier and the colloidal particle structure, and then freeze-dry to remove the moisture of the composite graphene hydrogel, so that the graphene sheet is stretched to form a porous network structure. As shown in Figure 2, the composite staggered stacked intercalation structure graphene-bismuthene aerogel is obtained;

The composite staggered stacked intercalation structure graphene-bismuthene aerogel of the present invention uses two-dimensional graphene as a building unit to form a three-dimensional nanomaterial, and has the characteristics of high electrical conductivity, large specific surface area, ultra-low density and high porosity. Compared with the pressure sensor prepared by the graphene airgel without adding bismuthene, the pressure sensor prepared by this composite interlaced stacked intercalation structure graphene-bismuthene airgel has larger relative changes in capacitance and resistance and higher sensitivity. The superior performance of this supercapacitor is due to the synergistic effect of the staggered intercalation structure formed by stacked bismuthene layers-stacked graphene layers. There are 80-100 micro-units per unit centimeter thickness, and each micro-unit is composed of 800-900 layers of single-layer graphene and 80-100 layers of bismuthene layers; The peak binding energy of .42eV corresponds to the C-Bi, C-C, C-O, C-N, C=O bonds respectively; the bismuthene layer and the graphene layer are formed by strong hydrogen bonds and C-Bi bonds. The synergistic effect of bismuthene and graphene realizes the design and construction of ion/electron dual transport channels in the airgel framework of the staggered intercalation structure. These structures possess abundant electrochemically active centers, high electrical conductivity, low interfacial resistance, and fast ion/electron transport, which facilitate electrolyte penetration and ensure electron transfer between layers, effectively increasing mass capacitance.

The beneficial effects of the present invention are:

1) Compared with the prior art, the aerogel exhibits cross-linked hierarchical structures of different sizes ranging from hundreds of nanometers to several micrometers by intercalating bismuthene between the graphene layered structures. Layered pores not only provide transport channels for ions or ionic groups in the electrolyte, but also help reveal active centers and increase double-layer capacitance, thereby improving electrochemical and pressure sensor performance; its density is 10-15 mg·cm ^-3 , and its structure is composed of elements C, O, N, and Bi.

2) The graphene-bismuthene airgel of the present invention will not undergo chemical reaction deterioration due to excessively active electrochemical activity; the energy density of the prepared symmetrical supercapacitor battery at 400W·Kg ^-1 is 45.55Wh·Kg ^-1 , and the cycle stability after 3600 charge and discharge cycles is 89.24%. The fabricated ion/electron capacitive sensor has an excellent sensitivity of ^0.326 kPa and a satisfactory durability during 1000 pressure loading cycles.

3) In addition, the supercapacitive pressure sensor based on the composite staggered stacked intercalated graphene airgel has a high sensitivity of 0.326kPa ^-1 in the stress range of 1.5-4.5kPa, and the fitting degree is 0.99; after 1000 cycles of pressing, the relative change of capacitance still retains 87% of the original value, and has high stress stability; it can sense small changes in strain (0.012%) and pressure (0.25Pa), and can effectively detect low pressure; Provides fast current response to external pressure changes; has supercapacitor characteristics, can provide high capacitance response, and has good electrochemical energy storage.

Description of drawings

Fig. 1 is a schematic structural view of the supercapacitive pressure sensor of the present invention, wherein 1 is a titanium foil, 2 is silver glue, and 3 is a micro-unit formed by graphene and bismuthene. The size _{of N1} is 80 to 100, and the right side is an enlarged view of a single micro-unit, wherein 4 is a graphene layer, and a single micro-unit contains about _N2 layers, _{and N2} has a size of 800-900.

Fig. 2 is a schematic diagram of the preparation of a composite staggered stacked intercalation structure graphene-bismuthene airgel and a local microscopic enlarged view of the present invention;

Fig. 3 is the SEM figure of airgel of the present invention, and wherein (a-c) is the SEM figure of different enlarged scales of redox graphene, and figure (d-f) is the SEM figure of different enlarged scales of composite interlaced stacked intercalation structure graphene-bismuthene airgel.

Fig. 4 is the XPS analysis diagram of the C element in the sample of Example 2 of the present invention, and its deconvoluted C1s peaks show peak binding energies of 284.1, 284.71, 285.69, 286.1 and 288.42eV, respectively corresponding to C-Bi, C-C, C-O, C-N, C=O bonds;

Fig. 5 is the GCD (galvanostatic charge and discharge) behavior of the sample electrode of Example 3 of the present invention at different densities, and the current density is from 0.64A·g ^-1 to 3A·g ^-1 ;

Fig. 6 is the relative capacitance change of the sample of Example 4 of the present invention under different pressure strains, and the stress change range is 0.5kPa to 4.5kPa;

Fig. 7 is the electrochemical cycle stability diagram of the supercapacitor after 3600 charge and discharge cycles of the sample of Example 5 of the present invention.

Fig. 8 is the relative change in capacitance of the sample of Example 6 of the present invention under a force of 1 kPa and a cycle pressure of 14k times; wherein the insets on the left and right represent enlarged views of some selected cycles from the beginning and end of the test.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below through the accompanying drawings and examples. However, it should be understood that the specific embodiments described here are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used herein in the description of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

Example 1

A method for preparing a composite staggered stacked intercalation structure graphene-bismuthene airgel, comprising the following steps:

1) Preparation of bismuthene: Mix 100 mg of bismuth powder and 0.50 g of (NH ₄ ) ₂ S ₂ O ₈ in a flask; then, add 5 mL of concentrated H ₂ SO ₄ and 1.2 mL of H ₂ O ₂ to the above mixed solution, seal it at room temperature for 12 hours, and then wash with ethanol 5 times to remove residual H ₂ SO ₄ ; 20 mg of the obtained dry powder and 1 mL of deionized water are sonicated for 6 hours in a sealed environment. Finally, the mixture was filtered to remove unexfoliated bismuth powder, and a bismuthene solution with a concentration of 0.014-0.017 g·mL ^-1 was obtained from the supernatant.

2) Preparation of composite staggered stacked intercalation structure hydrogel: First, 100 mg of graphene oxide was put into a mixed solution of 20 mL of deionized water and 0.8 mL of ammonia solution, and ultrasonically dispersed for 60 minutes. Then 5 mL of reduced graphene oxide solution was mixed with 0.2 mL of bismuthene solution to prepare a mixed solution. The precursor solution was sealed in a 10 mL polytetrafluoroethylene-lined autoclave at 120 °C for 12 h. Subsequently, the hydrogel was dialyzed against a mixture of CH ₃ CH ₂ OH/H ₂ O (1:100, V:V) for 6 hours and cooled to room temperature. A composite staggered stacked intercalation structure graphene-bismuthene hydrogel was prepared.

3) Preparation of composite graphene-bismuthene staggered stacked intercalation structure airgel: the hydrogel obtained in step 2) was frozen in a refrigerator for 12 hours to obtain an airgel, which was named BiGA1.

As a comparison, when the bismuthene solution is not added in step 2), and the other steps remain unchanged, a graphene airgel is obtained, named NGA.

In this example, as shown in Figure 3, it was measured that the surface wrinkle and porosity of the SEM frame of the BiGA1 sample increased compared to NGA. In the SEM image of NGA, it was found that the surface was smoother and the porosity was small. The density of the BiGA1 sample was 11.1 mg·cm ^-3 , which was larger than that of NGA. The stacking between graphene sheets in the BiGA1 sample is significantly reduced, and its interior contains a hybrid structure, which is composed of elements C, O, N, and Bi, and its atomic number ratio ranges from 79.8%, 15%, 6%, and 0.2%, respectively. It was measured that the sample only needs 11.5kPa force when it is compressed to 50% strain for the first time, while the NGA sample needs 125kPa force, which shows that the BiGA1 sample added with bismuthene is softer, which is beneficial to improve the sensitivity.

Example 2

A method for preparing a composite staggered stacked intercalation structure graphene-bismuthene airgel, comprising the following steps:

1) Preparation of bismuthene: Mix 90 mg of bismuth powder and 0.40 g of (NH ₄ ) ₂ S ₂ O ₈ in a flask; then, add 4 mL of concentrated H ₂ SO ₄ and 1 mL of H ₂ O ₂ to the above mixed solution, seal it at room temperature for 10 hours, and then wash with ethanol 4 times to remove residual H ₂ SO ₄ ; 18 mg of the obtained dry powder and 1 mL of deionized water are sonicated in a sealed environment for 6 hours. Finally, the mixture was filtered to remove unexfoliated bismuth powder, and bismuthene was obtained from the supernatant.

2) Preparation of composite staggered stacked intercalation structure hydrogel: first, 80 mg of graphene oxide was put into a mixed solution of 15 mL of deionized water and 0.5 mL of ammonia solution, and ultrasonically dispersed for 50 minutes. Then 5 mL of reduced graphene oxide solution was mixed with 0.4 mL of bismuthene solution to prepare a mixed solution. The precursor solution was sealed in a 10 mL polytetrafluoroethylene-lined autoclave at 120 °C for 12 h. Subsequently, the hydrogel was dialyzed in a mixture of CH ₃ CH ₂ OH/H ₂ O (1:100, V:V) for 5-6 hours, and cooled to room temperature. A composite staggered stacked intercalation structure graphene-bismuthene hydrogel was prepared.

3) Preparation of composite graphene-bismuthene staggered stacked intercalation structure airgel: the hydrogel obtained in step 2) was frozen in a refrigerator for 12 hours to obtain an airgel, which was named BiGA2.

Example 3

A method for preparing a composite graphene-bismuthene staggered stacked intercalation structure airgel, comprising the following steps:

1) Preparation of bismuthene: Mix 90 mg of bismuth powder and 0.40 g of (NH ₄ ) ₂ S ₂ O ₈ in a flask; then, add 4 mL of concentrated H ₂ SO ₄ and 1 mL of H ₂ O ₂ to the above mixed solution, seal it at room temperature for 10 hours, and then wash with ethanol 4 times to remove residual H ₂ SO ₄ ; 18 mg of the obtained dry powder and 1 mL of deionized water are sonicated in a sealed environment for 6 hours. Finally, the mixture was filtered to remove unexfoliated bismuth powder, and bismuthene was obtained from the supernatant.

2) Preparation of composite staggered stacked intercalation structure hydrogel: first, 80 mg of graphene oxide was put into a mixed solution of 15 mL of deionized water and 0.5 mL of ammonia solution, and ultrasonically dispersed for 50 minutes. Then 5 mL of reduced graphene oxide solution was mixed with 0.8 mL of bismuthene solution to prepare a mixed solution. The precursor solution was sealed in a 10 mL Teflon-lined autoclave at 120 °C for 12 h. Subsequently, the hydrogel was dialyzed in a mixture of CH ₃ CH ₂ OH/H ₂ O (1:100, V:V) for 5-6 hours, and cooled to room temperature. A composite graphene-bismuthene hydrogel was prepared.

3) Preparation of composite graphene-bismuthene staggered stacked intercalation structure airgel: the hydrogel obtained in step 2) was frozen in a refrigerator for 12 hours to obtain an airgel, which was named BiGA3.

In this example, it was measured that the SEM frame of the BiGA3 sample has a small amount of complex wrinkle-like network connected to each other. Compared with NGA, the surface wrinkle and porosity are increased, and the density is 14.1 mg·cm ^-3 , compared with the increase in NGA volume. When the current density is 0.67A g ^-1 , the mass specific capacitance of the BiGA3 sample electrode is 400.83F g ^-1 , which is greatly improved compared with the mass specific capacitance of the NGA sample electrode of 275F g ^-1 . As shown in Figure 5, observe the GCD behavior of BiGA3 samples at high working current densities. The current density ranges from 0.64A·g ^-1 to 3A·g ^-1 , and the curves are still triangularly symmetrical, indicating the working potential of BiGA3 sample electrodes in high-rate charge-discharge mode.

Example 4

Preparation of a supercapacitive pressure sensor

1) Preparation of gel electrolyte: 3 g of PVA and 1.5 g of concentrated H ₂ SO ₄ were added to 30 mL of deionized water and completely dissolved at 80° C. for 60 min to form a gel electrolyte.

2) Preparation of the upper and lower electrodes of the composite staggered intercalation structure graphene-bismuthene airgel: the composite graphene-bismuthene staggered intercalation structure airgel was fixed on the titanium electrode through conductive silver paste, and dried to obtain the composite staggered intercalation structure graphene-bismuthene airgel electrode, that is, the graphene-bismuthene airgel/Ti electrode. Two pieces of graphene-bismuthene airgel/Ti electrodes used as negative and positive electrodes were immersed in the prepared gel electrolyte for 60 min, respectively. A polypropylene diaphragm paper with a size of 0.7-1.0cm2 is sandwiched between the two electrodes to realize a symmetrical all-solid-state supercapacitor, that is, a supercapacitive pressure sensor.

In this example, the pressure sensor is prepared based on the BiGA3 sample. The sensor has a sandwich structure, the upper and lower layers are titanium electrodes, and the middle layer is a composite interlaced stacked intercalation structure graphene-bismuth aerogel injected with gel electrolyte. As shown in Figure 6, it shows that when the pressure range is 0-1.5kPa, its stress sensitivity is 0.052kPa^-1, in the range of 1.5 ~ 4.5kPa, its sensitivity is 0.326kPa^-1, while the NGA-based sensor showed a sensitivity of 0.024kPa in the pressure range of 0-2.5kPa^-1, in the pressure range of 2.5 ~ 4.5kPa, its linear sensitivity is 0.282kPa^-1, the comparison of the data shows that the sensor has increased stress sensitivity and improved performance compared with the pressure sensor prepared by the NGA sample without adding bismuthene.

Example 5

Preparation of a supercapacitive pressure sensor

1) Preparation of gel electrolyte: 3 g of PVA and 1.5 g of concentrated H ₂ SO ₄ were added to 30 mL of deionized water and completely dissolved at 80° C. for 60 min to form a gel electrolyte.

2) Preparation of the upper and lower electrodes of the graphene-bismuthene airgel with a composite staggered intercalation structure: soak two pieces of graphene-bismuthene airgel/Ti electrodes as negative and positive electrodes in the prepared gel electrolyte for 60 min, respectively. A symmetric all-solid-state supercapacitor is realized by sandwiching a polypropylene separator paper with a size of 1.0 cm ^between the two electrodes.

In this example, the pressure sensor is prepared based on the BiGA3 sample. The sensor has a sandwich structure, the upper and lower layers are electrodes, and the middle layer is a composite interlaced stacked intercalation structure graphene-bismuthene airgel injected with gel electrolyte. As shown in Figure 7, it shows a significant capacity retention rate of 89.24% after 3600 charge-discharge cycles.

Example 6

Preparation of a supercapacitive pressure sensor

1) Preparation of gel electrolyte: 3 g of PVA and 1.5 g of concentrated H ₂ SO ₄ were added to 30 mL of deionized water and completely dissolved at 80° C. for 60 min to form a gel electrolyte.

2) Preparation of the upper and lower electrodes of the graphene-bismuthene airgel with a composite staggered intercalation structure: soak two pieces of graphene-bismuthene airgel/Ti electrodes as the negative electrode and the positive electrode in the prepared gel electrolyte for 60 minutes. A symmetric all-solid-state supercapacitor is realized by sandwiching a polypropylene separator paper with a size of 1.0 cm ^between the two electrodes.

In this embodiment, the pressure sensor is prepared based on the BiGA3 sample. As shown in Figure 8, after the sensor is pressed 1000 times, the relative capacitance change still retains 87% of the original value, and has high stress stability; the sensor is a sandwich structure, the upper and lower layers are electrodes, and the middle layer is a composite interleaved stacked intercalation structure graphene-bismuthene airgel injected with gel electrolyte, and its stress sensitivity is 0.73kPa^-1, the fitting degree is 0.99; the pressure sensor prepared based on NGA samples has a stress sensitivity of 0.04kPa^-1, the fitting degree is 0.96; the pressure sensor prepared based on the BiGA1 sample has a stress sensitivity of 0.10kPa^-1, the fitting degree is 0.99; the pressure sensor based on the BiGA2 sample preparation has a stress sensitivity of 0.15kPa^-1, with a goodness of fit of 0.99.

Table 1

Data comparison shows that compared with NGA, BiGA1, and BiGA2, the pressure sensor prepared based on BiGA3 samples has the best sensitivity, the highest fitting degree, the best elastic and compressible performance, and can sense small changes in strain and pressure. It can provide a rapid current response to external pressure changes, and has great advantages in electrochemical energy storage, supercapacitor characteristics, and cycle stability, and has the best performance.

In summary, comparing the pressure sensors prepared based on BiGA1, BiGA2, and BiGA3 samples, it can be found that the pressure sensor based on BiGA3 samples has the best stress sensitivity and the best performance.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A composite staggered stacked intercalation structure graphene-bismuthene airgel, in which a bismuthene layer is inserted between graphene layered structures to form a staggered stacked intercalation structure, with 80 to 100 micro-units per unit centimeter thickness, and each micro-unit is composed of 800-900 layers of stacked single-layer graphene and 80-100 stacked single-layer bismuthene layers. 2. The composite staggered stacked intercalation structure graphene-bismuthene aerogel according to claim 1, characterized in that, the bismuthene layer and the graphene layer are formed by strong hydrogen bonds and C-Bi bonds, the density of the airgel is 10-15 mg cm- ³ , and there is a double transmission channel for ions and electrons in the staggered stacked intercalation structure airgel frame. 14%-15%, 5%-6%, 0.2%-0.3%. 3. A method for preparing a composite staggered stacked intercalation structure graphene-bismuthene airgel, characterized in that, comprising the following steps: 1) Preparation of bismuthene: Mix bismuth powder and (NH ₄ ) ₂ S ₂ O ₈ in a flask; add concentrated H ₂ SO ₄ and H ₂ O ₂ , seal the reaction, wash with ethanol to remove residual H ₂ SO ₄ ; add deionized water to the obtained powder, and perform ultrasonic treatment; remove unstripped bismuth powder by filtration, and obtain a bismuthene solution with a concentration of 0.014 to 0.017 g·mL ^-1 from the supernatant; 2) Preparation of composite staggered stacked intercalation structure graphene-bismuthene hydrogel: First, put graphene oxide powder into a mixture of deionized water and ammonia solution, and ultrasonically disperse to obtain a reduced graphene oxide solution with a concentration of 0.004-0.008g·mL ^-1 ; Then, the above-mentioned reduced graphene oxide solution and the bismuthene solution prepared in 1) are mixed at a volume ratio (3-5): (0.2-1.2) to prepare a precursor solution; the precursor solution is sealed in a polytetrafluoroethylene-lined autoclave, and kept at a temperature of 100-120° C. for 10-14 hours to obtain a hydrogel with a staggered stacked intercalation structure; Subsequently, the hydrogel with staggered stacked intercalation structure was dialyzed in a V:V=1:100 mixture of CH ₃ CH ₂ OH/H ₂ O for 3 to 6 hours, and cooled to room temperature to obtain a composite staggered stacked intercalation structure graphene-bismuthene hydrogel; 3) Preparation of composite staggered stacked intercalation structure graphene-bismuthene airgel: the hydrogel obtained in step 2) was freeze-dried in a freeze-drying oven at -18 to -20°C for 10 to 12 hours to obtain an airgel. 4. A composite staggered stacked intercalation structure graphene-bismuthene airgel according to claim 1 or 2 or obtained by the preparation method of claim 3, characterized in that, at a current density of 0.6-1.0A·g ^-1 , the mass specific capacitance is 360-420F·g ^-1 . 5. the application of composite type staggered stacked intercalation structure graphene-bismuthene airgel in supercapacitive pressure sensor according to claim 4, it is characterized in that, described supercapacitive pressure sensor has sandwich structure, and its upper and lower floors are electrodes, interlayer is composite type staggered stacked intercalation structure graphene-bismuthene aerogel, and described composite type staggered stacked intercalation structure graphene-bismuthene airgel is filled with gel electrolyte. 6. application as claimed in claim 5, is characterized in that, described super capacitive pressure sensor adopts the method for following steps to prepare: 1) First add PVA and concentrated H ₂ SO ₄ to deionized water, and dissolve completely at 80-85°C to form a gel electrolyte; 2) Fix the composite graphene-bismuthene staggered intercalation structure airgel on the titanium electrode through conductive silver paste, and dry to obtain the composite staggered staggered intercalation structure graphene-bismuthene airgel electrode, that is, the graphene-bismuthene airgel/electrode; soak the two pieces of graphene-bismuthene airgel/electrode as the negative electrode and the positive electrode respectively in the gel electrolyte prepared in 1) for 50-60 minutes; sandwich a polypropylene separator paper with a size of ^0.7-1.0cm2 between the two electrodes , realizing a symmetrical all-solid-state supercapacitor. 7. The application according to any one of claims 5-6, characterized in that the pressure sensor has a sensitivity of 0.326 ^kPa within a stress range of 1.5 to 4.5 kPa, and after 1000 pressure load cycles, the relative change in capacitance can still be retained as 87% of the original value; an energy density of 45.55 Wh Kg is provided at 400 W·Kg ⁻¹ , and after 3600 charge and discharge cycles, the cycle ^stability reaches 8 9.24%.