A bifunctional implantable supercapacitor based on MXene composite liquid metal and a preparation method and application thereof

Abstract

The application belongs to the technical field of supercapacitors, and discloses a bifunctional implantable supercapacitor based on MXene composite liquid metal as well as a preparation method and application thereof. The bifunctional implantable supercapacitor comprises a lower packaging layer, and an integrated temperature energy storage positive electrode layer, a spacer layer, an integrated temperature energy storage negative electrode layer and an upper packaging layer arranged in sequence on the lower packaging layer. The bifunctional implantable supercapacitor can simultaneously serve as a body temperature temperature sensing temperature-sensitive element and an energy storage functional element, realizing multifunctional integrated utilization of energy storage and physiological signal sensing. The manufacturing process is simple, efficient, highly repeatable and low in cost. The obtained multifunctional implantable supercapacitor has excellent electrochemical performance and temperature response sensitivity, and is suitable for wearable electronic devices, implantable medical devices, intelligent health monitoring systems and bionic electronic devices and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of supercapacitors, and particularly relates to a dual-function implantable supercapacitor based on MXene composite liquid metal and a preparation method and application thereof. BACKGROUND

[0002] Supercapacitors are particularly suitable for continuous operation in biological environments due to their fast charge and discharge capability, excellent rate performance, long cycle stability, and controllable biocompatibility, thus having great potential in implantable energy storage devices. However, existing implantable supercapacitors usually only have a single function, which limits their compatibility with the development trend of intelligent integrated biomedical devices. Therefore, supercapacitors can be integrated with other functional modules to develop multifunctional energy storage systems, such as combining temperature sensing, biological signal acquisition, light / heat response, etc., to realize the intelligentization and integration of devices. Most multifunctional implantable devices still rely on external power supply, which violates the original design intention of self-powered and self-sensing integration. Moreover, supercapacitors that have both energy storage and physiological signal sensing functions have problems such as insufficient energy density and decreased electrochemical stability, and are often difficult to match the performance of dedicated supercapacitors in terms of energy storage performance. Therefore, producing dual-function implantable supercapacitors with high specific capacitance, long life, and flexible structure suitable for complex in-vivo environments is an important goal of current research.

[0003] Therefore, a dual-function implantable supercapacitor is needed. Among the many physiological signals, temperature changes not only reflect physical health, such as postoperative fever, inflammation, infection, etc., but also have the advantages of stability and easy acquisition. Temperature sensing supercapacitors not only reflect environmental or body temperature changes through capacitance changes, but also become a potential direction for integrating energy storage and sensing. However, existing temperature sensing supercapacitors generally use complex material systems or independent sensing units in addition to energy storage structures, which have complex preparation processes and are not conducive to the practical application of flexible and implantable systems.

[0004] MXene materials can be used as ideal electrode materials for constructing multifunctional supercapacitors due to their metal-level conductivity, excellent specific capacitance, and flexible film forming ability. However, MXene material sheets tend to tightly stack during film formation, resulting in limited ion diffusion channels, and the capacitance performance decreases under physiological conditions with low ion strength in the electrolyte environment. Another disadvantage is that the introduction of external electrolyte makes the implantable supercapacitor prone to rejection, infection, etc. when working in the body.

[0005] Therefore, how to provide an implantable supercapacitor with strong energy storage performance, strong sensing performance, high accuracy, biocompatibility, and the ability to simultaneously detect human temperature signals and energy storage functions is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0006] Therefore, the application provides a dual-functional implantable supercapacitor based on MXene composite liquid metal and a preparation method and application thereof.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] The dual-functional implantable supercapacitor based on MXene composite liquid metal comprises a lower packaging layer and, sequentially arranged on the lower packaging layer, an integrated temperature energy storage positive electrode layer, a spacer layer, an integrated temperature energy storage negative electrode layer and an upper packaging layer.

[0009] Most of the structures of the dual-functional implantable supercapacitor of the application are formed by film forming, cutting, layering and adhering, etc. simple process steps, which have temperature response characteristics while realizing efficient energy storage, realize the integration of energy supply and physiological signal monitoring, and significantly simplify the structure of the implanted system. The packaging layer adopts a PDMS film, which has high elasticity and compliance, serves as the substrate and packaging support layer of the device, reduces the damage of mechanical stimulation to the tissue, can be firmly combined with the electrode layer, prevents delamination and liquid infiltration, ensures stable operation of the device, has excellent biocompatibility, and does not cause immune rejection reaction; the integrated temperature energy storage positive electrode layer adopts a MXene / liquid metal composite film, which has high specific surface area and temperature response characteristics, the liquid metal provides a continuous conductive network, has good temperature response characteristics, and when the body temperature changes between 35℃ and 40℃, sensitive response characteristics are generated, the physiological part temperature is accurately fed back, and finally the electrode has high energy storage and temperature signal detection capabilities; the spacer layer adopts a biocompatible membrane, which absorbs physiological body fluid as an electrolyte, does not need to add organic or acid-base electrolyte, avoids the risk of toxicity, and can be long-term attached or implanted in the body without causing inflammatory reaction; the integrated temperature energy storage negative electrode layer adopts a MXene / liquid metal composite film, which ensures the matching of electrochemical performance, improves the energy conversion efficiency, realizes high power density and high cycle stability; finally, the packaging layer, the integrated temperature energy storage positive and negative electrode layers and the spacer layer are assembled together by using a simple assembly process, forming a dual-functional implantable supercapacitor with good performance.

[0010] The application further provides a preparation method of the dual-functional implantable supercapacitor, comprising the following steps:

[0011] (1) preparing the lower packaging layer: a flexible PDMS film with certain adhesion is formed by film forming technology;

[0012] (2) Preparation of integrated temperature energy storage positive electrode layer: MXene / liquid metal composite film is used and cut into a fixed shape; the fixed-shape electrode is attached to the flexible PDMS film described in step (1), and the lead-out electrode is attached between the flexible PDMS film and the fixed-shape electrode layer;

[0013] (3) Preparation of spacer layer: Place a biocompatible membrane of the same shape above the fixed-shape electrode in step (2) to absorb biological physiological fluids;

[0014] (4) Preparation of integrated temperature energy storage negative electrode layer: MXene / liquid metal composite film is used and cut into the same shape as the positive electrode layer in step (2) to obtain the negative electrode layer; the negative electrode layer is placed on top of the biocompatible membrane described in step (3);

[0015] (5) Preparation of upper encapsulation layer: A flexible PDMS film with certain adhesion is formed by using film forming technology. The flexible PDMS film is then bonded to the lower encapsulation layer described in step (1) in a non-completely closed manner to obtain the final product.

[0016] This invention integrates temperature sensing and energy storage materials, enabling the electrode material to sense temperature changes in real time while storing energy, eliminating the need for additional power modules and temperature sensors. This achieves integrated energy supply and body temperature monitoring, reducing the size and complexity of implantable devices. Furthermore, the integrated temperature and energy storage electrode layer possesses a high specific surface area and excellent pseudocapacitive properties. A biocompatible spacer layer absorbs physiological fluids, preventing inflammatory reactions or electrolyte leakage. A flexible encapsulation layer ensures good flexibility and biocompatibility while preventing external contamination.

[0017] Preferably, the specific operation of the film-forming technology described in steps (1) and (5) is as follows: the PDMS matrix and curing agent are mixed at a mass ratio of 10:1 and degassed to form a prepolymer solution, which is then spin-coated into a 10-50 μm film. After film formation, the film is pre-cured at 50-80℃ for 5-30 min to make the film surface viscous, and then cured at 60-80℃ for 1-2 h to obtain a flexible PDMS film.

[0018] Preferably, the liquid metal in steps (2) and (4) is selected from gallium, indium, and gallium-indium alloy.

[0019] Preferably, the MXene mentioned in steps (2) and (4) is an MXene-type two-dimensional nanomaterial obtained by selectively etching MAX phase materials;

[0020] The MAX phase material is selected from one of Ti3AlC2, Ti3AlCN, Nb2AlC, and Mo2AlTiC2;

[0021] The MXene type two-dimensional nanomaterial is selected from one of Ti3C2T x , Ti3CNT x , Nb2CT x , Mo2TiC2T x .

[0022] Preferably, the specific preparation process of the MXene / liquid metal composite film in steps (2) and (4) is that the MXene colloidal suspension and the liquid metal nanodroplet suspension are stirred and mixed in an ice bath for 1-2 hours of ultrasonic stirring, vacuum filtration, drying in a vacuum oven, and then the MXene / liquid metal composite film is obtained.

[0023] Preferably, the amount of the liquid metal accounts for 5-20% of the total solid mass of the liquid metal and the MXene.

[0024] Further preferably, the amount of the liquid metal accounts for 10% of the total solid mass of the liquid metal and the MXene.

[0025] Preferably, the vacuum filtration device comprises a filtration bottle, a filtration cup, a cup cover, a sand core filter head, a clamp, a silica gel tube and a vacuum pump; the filtration cup is 300 mL, and the filtration bottle is 1000 mL; the ice bath ultrasonic device comprises a sound wave generator, an ultrasonic probe, a reaction container and a cooling system; the ultrasonic amplitude bar is 8 mm, and the frequency is 20 kHz.

[0026] Preferably, the cutting method in steps (2) and (4) is selected from one of laser direct writing, die cutting, plasma etching, photolithography and mechanical cutting.

[0027] The integrated temperature energy storage electrode layer of the application is a fixed shape MXene / liquid metal composite film, the MXene has excellent pseudo-capacitance performance and temperature sensitive conductance characteristics, and the addition of the liquid metal provides good thermal responsiveness. The combination of the two not only can efficiently store energy but also can realize real-time temperature change sensing, so that the device can realize the functions of electrochemical energy supply and body temperature signal detection at the same time in the same structure, and the system integration is significantly improved. In the process of film compounding, the filtration method forms a dense and continuous film structure, the internal pore distribution of the electrode is controllable, the ion migration channel is stable and uniform, and the energy storage performance is improved. The temperature sensing performance is mainly determined by the thermal response performance of the composite film. Since the liquid metal is added in the MXene / liquid metal composite film, the content of the liquid metal has a great influence on the temperature detection performance of the MXene / liquid metal composite film.

[0028] Preferably, the biocompatible separator in step (3) is selected from one of a cellulose separator, a chitosan separator, a gelatin separator, a silk fibroin separator, a polyvinyl alcohol separator and a polyurethane separator.

[0029] Preferably, the biological physiological fluid in step (3) comprises at least one of blood, sweat, and interstitial fluid.

[0030] The application also provides the application of the above-mentioned bifunctional implantable supercapacitor or the bifunctional implantable supercapacitor prepared by the above-mentioned preparation method in wearable electronic devices, implantable medical devices, intelligent health monitoring systems, and bionic electronic devices.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] The manufacturing process of the application includes vacuum filtration technology, material modification technology, and layering assembly technology, and a flexible body temperature monitoring-energy storage integrated bifunctional implantable supercapacitor is prepared, which can simultaneously serve as a body temperature sensing temperature-sensitive element and an energy storage functional element, realizing the multifunctional integration of energy storage and physiological signal sensing. The manufacturing process is simple, efficient, highly repeatable, and low in cost; the obtained multifunctional implantable supercapacitor has excellent electrochemical performance and temperature response sensitivity, and is suitable for wearable electronic devices, implantable medical devices, intelligent health monitoring systems, and bionic electronic devices. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. The drawings in the description are only embodiments of the application.

[0034] Figure 1 FIG. 1 is a cross-sectional schematic view of the bifunctional implantable supercapacitor of the application; wherein: 1 is an upper packaging layer, 2 is an integrated temperature energy storage negative electrode layer, 3 is a spacing layer, 4 is an integrated temperature energy storage positive electrode layer, and 5 is a lower packaging layer.

[0035] Figure 2 FIG. 2 is a front view of the bifunctional implantable supercapacitor of the application.

[0036] Figure 3 FIG. 3 is an electron microscope image of the MXene / liquid metal composite film of Example 2.

[0037] Figure 4 FIG. 4 is a comparison of the mass specific capacitance column chart of the MXene / liquid metal composite film in Examples 1-4 and the Ti3C2T x film in the comparative example.

[0038] Figure 5 FIG. 5 is a cyclic voltammogram of the bifunctional implantable supercapacitor of Example 2 at 35℃ at different scanning rates.

[0039] Figure 6Cyclic voltammograms of the bifunctional implantable supercapacitor of Example 2 at different body temperatures. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0041] The device used for vacuum filtration in the embodiments includes a filtration bottle, a filtration cup, a cup cover, a sand core filter head, a clamp, a silica gel tube, and a vacuum pump. The filtration cup is 300 mL, and the filtration bottle is 1000 mL. The device for ice bath ultrasonic includes a sound wave generator, an ultrasonic probe, a reaction container, and a cooling system. The ultrasonic amplitude rod is 8 mm, and the frequency is 20 kHz.

[0042] Embodiment 1

[0043] A preparation method of a bifunctional implantable supercapacitor based on MXene composite liquid metal includes the following steps:

[0044] (1) Preparation of Ti3C2T x Nanosheet colloidal suspension: 6.4 g of LiF was dispersed in 80 mL of 12M HCl solution, and the LiF / HCl mixed solution was stirred at 30°C for 5 minutes, then 4 g of Ti3AlC2 powder was slowly added into the LiF / HCl mixed solution. The mixture was continuously stirred at 30°C for 24 h, then the product was thoroughly washed with deionized water and centrifuged at 3500 rpm for 5 min for several times until the supernatant after centrifugation became neutral. Finally, the multilayer Ti3C2T x Nanosheet was delaminated by hand shaking and repeatedly centrifuged at 3500 rpm for 5 min, and the supernatant was collected to obtain few-layer 10 mg·mL -1 Ti3C2T x Nanosheet colloidal suspension;

[0045] (2) Preparation of liquid metal nanosphere dispersion: 150 mg of liquid metal (GaIn alloy, 75% Ga and 25% In) was added into 30 mL of deionized water and pre-stirred for 30 min, then ultrasonic and stirring was carried out at 10°C in an ice bath environment for 1.5 h, after stopping ultrasonic, stirring was carried out for another 30 min, and a uniformly dispersed 5 mg·mL -1 Liquid metal nanosphere dispersion was obtained;

[0046] (3) Preparation of Ti3C2T xPreparation of liquid metal composite films: A uniformly dispersed liquid metal nanosphere dispersion and a few-layer Ti3C2T... x The suspension was mixed, and the mixture was sonicated for 30 minutes, then stirred thoroughly for 1 hour; then Ti3C2T x The liquid metal mixture was filtered through a vacuum filtration device to form a film, which was then transferred to a vacuum drying oven and dried at 30°C for 12 hours. The amount of liquid metal used accounted for 5% of the total solid mass of the liquid metal and MXene.

[0047] (4) Preparation of PDMS film: After degassing, the PDMS prepolymer and curing agent are mixed at a mass ratio of 10:1 and then dropped onto the substrate. First, the pre-spreading is carried out by spin coating at 500 rpm for 10 s, and then the uniform film of 25 μm is formed by spin coating at 3000 rpm for 40 s. Then, the film is cured at 70℃ for 60 min to obtain a flexible, smooth surface and good adhesion PDMS encapsulation film.

[0048] (5) Assembly of a bifunctional implantable supercapacitor based on MXene composite liquid metal: Two identical 0.5cm×0.5cm Ti3C2T supercapacitors were cut using mechanical cutting technology. x The liquid metal composite film uses a cellulose membrane as the electrolyte absorber and 0.01M PBS as the electrolyte. It is encapsulated by a 25μm PDMS film in a bottom-up order, and silver wire is used as a current collector to connect the electrodes to an external circuit.

[0049] Example 2

[0050] A method for fabricating a bifunctional implantable supercapacitor based on MXene composite liquid metal includes the following steps:

[0051] (1) Ti3C2T x Preparation of nanosheet colloidal suspension: 6.4 g LiF was dispersed in 80 mL of 12 M HCl solution. The LiF / HCl mixture was stirred at 30 °C for 5 minutes. Then, 4 g Ti3AlC2 powder was slowly added to the LiF / HCl mixture. The mixture was stirred continuously at 30 °C for 24 h. The product was then thoroughly washed with deionized water and centrifuged multiple times at 3500 rpm for 5 minutes until the supernatant became neutral. Finally, the multilayer Ti3C2T nanosheet colloidal suspension was prepared by hand shaking. x The nanosheets were separated into layers, and the layers were repeatedly centrifuged at 3500 rpm for 5 min. The supernatant was collected to obtain a fractional layer of 10 mg / mL. -1 Ti3C2T x Nanosheet colloidal suspension;

[0052] (2) Preparation of liquid metal nanosphere dispersion liquid: 150 mg of liquid metal (GaIn alloy, 75% Ga and 25% In) was added to 30 mL of deionized water and pre-stirred for 30 min, then ultrasonicated and stirred for 1.5 h in an ice bath environment at 10℃, and stirred for another 30 min after stopping ultrasonication to obtain a uniformly dispersed 5 mg·mL -1 liquid metal nanosphere dispersion liquid;

[0053] (3) Preparation of Ti3C2T x / liquid metal composite film: the uniformly dispersed liquid metal nanosphere dispersion liquid and the few-layer Ti3C2T x suspension were mixed, the mixed solution was ultrasonicated for 30 min and then fully stirred for 1 h; then the Ti3C2T x / liquid metal mixed solution was filtered into a film by a vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30℃ for 12 h to obtain a MXene / liquid metal composite film; the amount of liquid metal was 10% of the total solid mass of liquid metal and MXene;

[0054] (4) Preparation of PDMS film: after the PDMS prepolymer and the curing agent were mixed and degassed at a mass ratio of 10:1, they were added dropwise to the substrate, pre-spread at 500 rpm for 10 s, and then spin-coated at 3000 rpm for 40 s to form a uniform film of 25 μm, followed by curing at 70℃ for 60 min to obtain a flexible, smooth and well-adhesive PDMS packaging film;

[0055] (5) Assembly of a dual-functional implantable supercapacitor based on MXene composite liquid metal: two Ti3C2T x / liquid metal composite films with the same size of 0.5 cm×0.5 cm were cut out using a mechanical cutting technique, a cellulose separator was used as an electrolyte-absorbing material, 0.01M PBS was used as an electrolyte, and the electrodes were connected to an external circuit.

[0056] Example 3

[0057] A preparation method of a dual-functional implantable supercapacitor based on MXene composite liquid metal, comprising the following steps:

[0058] (1) Preparation of Ti3C2T xPreparation of nanosheet colloidal suspension: 6.4 g of LiF was dispersed in 80 mL of 12 M HCl solution, the LiF / HCl mixed solution was stirred at 30 °C for 5 min, then 4 g of Ti3AlC2 powder was slowly added into the LiF / HCl mixed solution. The mixture was continuously stirred at 30 °C for 24 h, then the product was thoroughly washed with deionized water and centrifuged at 3500 rpm for 5 min for several times until the supernatant after centrifugation became neutral. Finally, the multilayer Ti3C2T x nanosheets were delaminated and repeatedly centrifuged at 3500 rpm for 5 min, and the supernatant was collected to obtain few-layer 10 mg·mL -1 Ti3C2T x nanosheet colloidal suspension;

[0059] (2) Preparation of liquid metal nanosphere dispersion solution: 150 mg of liquid metal (GaIn alloy, 75% Ga and 25% In) was added to 30 mL of deionized water and pre-stirred for 30 min, then ultrasonicated and stirred for 1.5 h in an ice bath environment at 10 °C, and stirred for another 30 min after stopping ultrasonication to obtain a uniformly dispersed 5 mg·mL -1 liquid metal nanosphere dispersion solution;

[0060] (3) Preparation of Ti3C2T x / liquid metal composite film: the uniformly dispersed liquid metal nanosphere dispersion solution and few-layer Ti3C2T x suspension were mixed, the mixed solution was ultrasonicated for 30 min and then thoroughly stirred for 1 h. Then the Ti3C2T x / liquid metal mixed solution was filtered into a film by a vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30 °C for 12 h; the amount of liquid metal accounted for 15% of the total solid mass of liquid metal and MXene;

[0061] (4) Preparation of PDMS film: after the PDMS prepolymer and curing agent were mixed and degassed at a mass ratio of 10:1, they were added dropwise to the substrate, pre-spread at 500 rpm for 10 s, then spin-coated at 3000 rpm for 40 s to form a uniform film of 25 μm, and then cured at 70 °C for 60 min to obtain a flexible, smooth and well-adhesive PDMS packaging film;

[0062] (5) Assembly of bifunctional implantable supercapacitor based on MXene composite liquid metal: two 0.5 cm x 0.5 cm Ti3C2T x / liquid metal composite film, with cellulose diaphragm as the material for absorbing electrolyte, and 0.01M PBS as the electrolyte, packaged by 25μm PDMS film in the order from bottom to top, silver wire as current collector, and electrode connected to external circuit.

[0063] Example 4

[0064] A preparation method of a bifunctional implantable supercapacitor based on MXene composite liquid metal, comprising the following steps:

[0065] (1) Preparation of Ti3C2T x Preparation of nanosheet colloidal suspension: 6.4g LiF was dispersed in 80 mL 12M HCl solution, the LiF / HCl mixed solution was stirred at 30℃ for 5min, then 4g Ti3AlC2 powder was slowly added into the LiF / HCl mixed solution. The mixture was continuously stirred at 30℃ for 24h, then the product was thoroughly washed with deionized water and centrifuged at 3500rpm for 5min for several times until the supernatant after centrifugation became neutral. Finally, the multilayer Ti3C2T x nanosheets were delaminated by hand shaking and repeatedly centrifuged at 3500rpm for 5min, and the supernatant was collected to obtain few-layer 10mg·mL -1 Ti3C2T x nanosheet colloidal suspension;

[0066] (2) Preparation of liquid metal nanosphere dispersion: 150mg liquid metal (GaIn alloy, 75% Ga and 25% In) was added into 30mL deionized water and pre-stirred for 30min, then ultrasonicated and stirred for 1.5h in an ice bath environment at 10℃, and after stopping ultrasonication, stirred for another 30min to obtain uniformly dispersed 5mg·mL -1 liquid metal nanosphere dispersion;

[0067] (3) Preparation of Ti3C2T x / liquid metal composite film: the uniformly dispersed liquid metal nanosphere dispersion and few-layer Ti3C2T x suspension were mixed, the mixed solution was ultrasonicated for 30min and then fully stirred for 1h; then the Ti3C2T x / liquid metal mixed solution was filtered into a film by vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30℃ for 12h; the amount of liquid metal accounted for 20% of the total solid mass of liquid metal and MXene;

[0068] (4) Preparation of PDMS film: After the PDMS prepolymer and curing agent were mixed in a mass ratio of 10:1 and degassed, they were added dropwise to the substrate, pre-spreading was performed at 500 rpm for 10 s, and then a uniform film of 25 μm was formed by spin coating at 3000 rpm for 40 s, followed by curing at 70 °C for 60 min, obtaining a flexible, smooth and well-adhesive PDMS packaging film;

[0069] (5) Assembly of a dual-functional implantable supercapacitor based on MXene composite liquid metal: Two Ti3C2T x / metal composite films with the same size of 0.5 cm x 0.5 cm were cut out using a mechanical cutting technique, a cellulose separator was used as an electrolyte-absorbing material, and 0.01 M PBS was used as an electrolyte. The electrode was packaged by 25 μm PDMS film in the order from bottom to top, and silver wire was used as the current collector. The electrode was connected to the external circuit.

[0070] Example 5

[0071] A preparation method of a dual-functional implantable supercapacitor based on MXene composite liquid metal, comprising the following steps:

[0072] (1) Preparation of Ti3CNT x nanosheet colloidal suspension: 6.4 g of LiF was dispersed in 80 mL of 12 M HCl solution, the LiF / HCl mixed solution was stirred at 30 °C for 5 min, then 4 g of Ti3AlCN powder was slowly added to the LiF / HCl mixed solution. The mixture was continuously stirred at 30 °C for 24 h, then the product was thoroughly washed with deionized water and centrifuged at 3500 rpm for 5 min several times until the supernatant after centrifugation became neutral. Finally, the multilayer Ti3CNT x nanosheet was delaminated by hand shaking and centrifuged at 3500 rpm for 5 min repeatedly, and the supernatant was collected to obtain a few-layer 10 mg·mL -1 Ti3CNT x nanosheet colloidal suspension;

[0073] (2) Preparation of liquid metal nanosphere dispersion: 150 mg of liquid metal (GaIn alloy, 75% Ga and 25% In) was added to 30 mL of deionized water and pre-stirred for 30 min, then ultrasonicated and stirred for 1.5 h in an ice bath environment at 10 °C. After stopping ultrasonication, it was stirred for another 30 min to obtain a uniformly dispersed 5 mg·mL -1 liquid metal nanosphere dispersion;

[0074] (3) Ti3CNT xPreparation of liquid metal composite film: The uniformly dispersed liquid metal nanosphere dispersion liquid and few-layer Ti3C2T x The suspension was mixed, the mixed solution was ultrasonicated for 30 min, and then fully stirred for 1 h. Then, the Ti3C2T x The liquid metal mixture was filtered into a film by a vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30°C for 12 h. The amount of liquid metal accounted for 10% of the total solid mass of liquid metal and MXene;

[0075] (4) Preparation of PDMS film: After the PDMS prepolymer and the curing agent were mixed and degassed at a mass ratio of 10:1, they were added dropwise to the substrate. First, pre-spreading was performed at 500 rpm for 10 s, and then uniform film formation was performed at 3000 rpm for 40 s to form a 25 μm uniform film. Subsequently, curing was performed at 70°C for 60 min to obtain a flexible, smooth-surfaced, and well-adhesive PDMS packaging film;

[0076] (5) Assembly of a dual-functional implantable supercapacitor based on MXene composite liquid metal: Two Ti3C2T x Liquid metal composite film, cellulose diaphragm was used as the material for absorbing electrolyte, and 0.01M PBS was used as the electrolyte. The electrode was connected to the external circuit with silver wire as the current collector.

[0077] Example 6

[0078] A preparation method of a dual-functional implantable supercapacitor based on MXene composite liquid metal, comprising the following steps:

[0079] (1) Preparation of Ti3C2T x Preparation of nanosheet colloidal suspension: 6.4 g of LiF was dispersed in 80 mL of 12M HCl solution, and the LiF / HCl mixed solution was stirred at 30°C for 5 min. Then, 4 g of Ti3AlC2 powder was slowly added to the LiF / HCl mixed solution. The mixture was continuously stirred at 30°C for 24 h, and then the product was thoroughly washed with deionized water and centrifuged at 3500 rpm for 5 min several times until the supernatant after centrifugation became neutral. Finally, the multilayer Ti3C2T x nanosheets were delaminated by hand shaking and repeatedly centrifuged at 3500 rpm for 5 min, and the supernatant was collected to obtain 10 mg·mL -1 few-layer Ti3C2T x nanosheet colloidal suspension;

[0080] (2) Preparation of liquid metal nanosphere dispersion liquid: 150 mg of liquid metal (GaIn alloy, 75% Ga and 25% In) was added to 30 mL of deionized water and pre-stirred for 30 min, then ultrasonicated and stirred for 1.5 h in an ice bath environment at 10℃, and after stopping ultrasonication, stirred for another 30 min to obtain a uniformly dispersed 5 mg·mL -1 liquid metal nanosphere dispersion liquid;

[0081] (3) Preparation of Ti3C2T x / liquid metal composite film: the uniformly dispersed liquid metal nanosphere dispersion liquid and the few-layer Ti3C2T x suspension were mixed, the mixed solution was ultrasonicated for 30 min, and then stirred for 1 h, then the Ti3C2T x / liquid metal mixed solution was filtered into a film by a vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30℃ for 12 h; the amount of liquid metal was 10% of the total solid mass of liquid metal and MXene;

[0082] (4) Preparation of PDMS film: after the PDMS prepolymer and the curing agent were mixed and degassed at a mass ratio of 10:1, they were added dropwise to the substrate, pre-spread at 500 rpm for 10 s, then spin-coated at 3000 rpm for 40 s to form a uniform film of 50 μm, and then cured at 70℃ for 60 min to obtain a flexible, smooth and well-adhesive PDMS packaging film;

[0083] (5) Assembly of a dual-functional implantable supercapacitor based on MXene composite liquid metal: two Ti3C2T x / liquid metal composite films with the same size of 1 cm×1 cm were cut by mechanical cutting technology, a cellulose separator was used as an electrolyte-absorbing material, 0.01M PBS was used as an electrolyte, and the assembly was packaged by 50 μm PDMS film from bottom to top, and silver wire was used as a current collector to connect the electrode to an external circuit.

[0084] Example 7

[0085] A preparation method of a dual-functional implantable supercapacitor based on MXene composite liquid metal, comprising the following steps:

[0086] (1) Ti3C2T xPreparation of nanosheet colloidal suspension: 6.4 g of LiF was dispersed in 80 mL of 12M HCl solution, the LiF / HCl mixed solution was stirred at 30°C for 5 min, then 4 g of Ti3AlCN powder was slowly added into the LiF / HCl mixed solution. The mixture was continuously stirred at 30°C for 24 h, then the product was thoroughly washed with deionized water and centrifuged at 3500 rpm for 5 min for multiple times until the supernatant after centrifugation became neutral; finally, the multilayer Ti3CNT x nanosheets were delaminated and repeatedly centrifuged at 3500 rpm for 5 min, and the supernatant was collected to obtain few-layer 10 mg·mL -1 Ti3CNT x nanosheet colloidal suspension;

[0087] (2) Preparation of liquid metal nanosphere dispersion solution: 150 mg of liquid metal (Ga) was added to 30 mL of deionized water and pre-stirred for 30 min, then ultrasonicated and stirred for 1.5 h in an ice bath environment at 10°C, and after the ultrasonication was stopped, it was stirred for another 30 min to obtain a uniformly dispersed 5 mg·mL -1 liquid metal nanosphere dispersion solution;

[0088] (3) Preparation of Ti3CNT x / liquid metal composite film: the uniformly dispersed liquid metal nanosphere dispersion solution and few-layer Ti3CNT x suspension were mixed, the mixed solution was ultrasonicated for 30 min and then thoroughly stirred for 1 h, then the Ti3CNT x / liquid metal mixed solution was filtered into a film by a vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30°C for 12 h; the amount of liquid metal accounted for 10% of the total solid mass of liquid metal and MXene;

[0089] (4) Preparation of PDMS film: after the PDMS prepolymer and the curing agent were mixed and degassed at a mass ratio of 10:1, they were added dropwise to the substrate, pre-spread at 500 rpm for 10 s, then formed a uniform film of 25 μm by spin coating at 3000 rpm for 40 s, and then cured at 70°C for 60 min to obtain a flexible, smooth and well-adhesive PDMS packaging film;

[0090] (5) Assembly of bifunctional implantable supercapacitor based on MXene composite liquid metal: two Ti3C2T x / liquid metal composite films with the same size of 1 cm×1 cm were cut out by mechanical cutting technology, cellulose diaphragm was used as the material for absorbing electrolyte, 0.01M PBS was used as the electrolyte, and the packaging was carried out from bottom to top by 25 μm PDMS film, silver wire was used as the current collector, and the electrodes were connected to the external circuit.

[0091] Comparative Example

[0092] The preparation method of the pure MXene implantable supercapacitor comprises the following steps:

[0093] (1) Ti3C2T x Preparation of nanosheet colloidal suspension: 6.4 g of LiF was dispersed in 80 mL of 12M HCl solution, the LiF / HCl mixed solution was stirred at 30°C for 5 minutes, and then 4 g of Ti3AlC2 powder was slowly added into the LiF / HCl mixed solution. The mixture was continuously stirred at 30°C for 24 h, then the product was thoroughly washed with deionized water and centrifuged at 3500 rpm for 5 min for multiple times until the supernatant after centrifugation became neutral. Finally, the multilayer Ti3C2T x nanosheets were delaminated by hand shaking and repeatedly centrifuged at 3500 rpm for 5 min, and the supernatant was collected to obtain few-layer 10 mg·mL -1 Ti3C2T x nanosheet colloidal suspension;

[0094] (2) Preparation of Ti3C2T x thin film: the few-layer Ti3C2T x suspension was ultrasonically treated for 30 min, and then stirred for 1 h, and then the Ti3C2T x suspension was filtered into a film by a vacuum filtration device, and the film was transferred to a vacuum drying oven for drying at 30°C for 12 h;

[0095] (4) Preparation of PDMS thin film: after the PDMS prepolymer and the curing agent were mixed and degassed at a mass ratio of 10:1, they were added dropwise to the substrate, pre-spreading was performed at 500 rpm for 10 s, and then uniform thin film with a thickness of 50 μm was formed by spin coating at 3000 rpm for 40 s, followed by curing at 70°C for 60 min, to obtain a flexible, smooth and well-adhesive PDMS packaging film;

[0096] (5) Assembly of pure MXene implantable supercapacitor: two Ti3C2T x thin films with the same size of 0.5 cm x 0.5 cm were cut out by mechanical cutting technology, cellulose diaphragm was used as the material for absorbing electrolyte, 0.01M PBS was used as electrolyte, and the assembly was packaged by 25 μm PDMS film from bottom to top, silver wire was used as current collector, and the electrode was connected to external circuit.

[0097] Figure 1A cross-sectional schematic view of the bifunctional implantable supercapacitor of the present application; wherein: 1 - upper encapsulation layer, 2 - integrated temperature energy storage negative electrode layer, 3 - spacer layer, 4 - integrated temperature energy storage positive electrode layer, 5 - lower encapsulation layer. Figure 2 A front view schematic of the bifunctional implantable supercapacitor of the present application.

[0098] Performance test method and results of the product of Example 2:

[0099] Figure 3 An electron microscope image of the MXene / liquid metal composite film of Example 2, which shows that the liquid metal is uniformly distributed on the surface of the MXene. Figure 4 A mass specific capacitance column chart of the MXene / liquid metal composite film in Examples 1-4 and the Ti3C2T x film in the comparative example. It can be seen that the mass specific capacitance of Example 2 is the highest. The cyclic voltammogram of the bifunctional implantable supercapacitor of Example 2 at 35℃ was tested at different scan rates, and the scan rates were 2mV·s -1 , 5mV·s -1 , 10mV·s -1 , 20mV·s -1 , 50mV·s -1 , as shown in Figure 5 , which shows that the supercapacitor of the present application has a higher mass specific capacitance. The cyclic voltammogram of the bifunctional implantable supercapacitor of Example 2 was tested at different body temperatures, and the temperatures were 35℃, 36℃, 37℃, 38℃, 39℃, and 40℃, as shown in Figure 6 , the specific capacitance was calculated, and different mass specific capacitances were obtained at different temperatures. It can be shown that the supercapacitor of the present application can monitor the temperature by changing the mass specific capacitance, realizing the multifunctional integration of energy storage and temperature monitoring. The liquid metal can provide good temperature sensing performance, the MXene can provide good capacitive storage capacity, and different PDMS film thicknesses can better adapt to different mechanical stress positions in the body and the service life of the device. The biocompatible separator can absorb biological physiological fluids, including at least one of blood, sweat, and interstitial fluid.

[0100] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent substitutions for some technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A bifunctional implantable supercapacitor based on MXene composite liquid metal, characterized in that, It comprises: a lower encapsulation layer, and an integrated temperature energy storage positive electrode layer, a spacer layer, an integrated temperature energy storage negative electrode layer and an upper encapsulation layer arranged in sequence on the lower encapsulation layer; The preparation method of the bifunctional implantable supercapacitor comprises the following steps: (1) preparing a lower encapsulation layer: using film forming technology to form a flexible PDMS film with certain adhesion; (2) preparing an integrated temperature energy storage positive electrode layer: using MXene / liquid metal composite film, cutting into a fixed shape; adhering the fixed shape electrode to the flexible PDMS film in step (1), and adhering the lead-out electrode between the flexible PDMS film and the fixed shape electrode layer; (3) preparing a spacer layer: placing a biocompatible separator with the same shape on the fixed shape electrode in step (2) to absorb biological physiological body fluids; (4) preparing an integrated temperature energy storage negative electrode layer: using MXene / liquid metal composite film, cutting into the same shape as the positive electrode layer in step (2) to obtain a negative electrode layer; placing the negative electrode layer on the biocompatible separator in step (3); (5) preparing an upper encapsulation layer: using film forming technology to form a flexible PDMS film with certain adhesion, and forming a non-fully closed adhesion between the flexible PDMS film and the lower encapsulation layer in step (1), thereby obtaining the bifunctional implantable supercapacitor. The liquid metal in steps (2) and (4) is selected from one of gallium, indium, and gallium-indium alloy.

2. The dual function implantable supercapacitor of claim 1, wherein, The specific operation of the film forming technology in steps (1) and (5) is: mixing the PDMS base and the curing agent at a mass ratio of 10:1 to form a prepolymer solution, spin coating into a 10-50 μm film, pre-curing at 50-80°C for 5-30 min after film forming to make the film surface sticky, and curing at 60-80°C for 1-2 h to obtain a flexible PDMS film.

3. The dual function implantable supercapacitor of claim 1, wherein, The MXene in steps (2) and (4) is a MXene type two-dimensional nanomaterial obtained by selective etching of a MAX phase material; The MAX phase material is selected from one of Ti3AlC2, Ti3AlCN, Nb2AlC, and Mo2AlTiC2; The MXene-based two-dimensional nanomaterial is selected from one of Ti3C2T x , Ti3CNT x , Nb2CT x , Mo2TiC2T x .

4. The dual function implantable supercapacitor of claim 1, wherein, The specific preparation process of the MXene / liquid metal composite film in steps (2) and (4) is: stirring and mixing the MXene colloidal suspension and the liquid metal nanodroplet suspension for 1-2 h by ice bath ultrasonic, vacuum filtration, and drying in a vacuum oven.

5. The dual function implantable supercapacitor of claim 4, wherein, The amount of liquid metal accounts for 5-20% of the total solid mass of liquid metal and MXene.

6. The dual function implantable supercapacitor of claim 1, wherein, The biocompatible separator in step (3) is selected from one of cellulose separator, chitosan separator, gelatin separator, silk fibroin separator, polyvinyl alcohol separator, and polyurethane separator.

7. The dual function implantable supercapacitor of claim 1, wherein, The biological physiological body fluid in step (3) includes at least one of blood, sweat, and interstitial fluid.

8. The application of the bifunctional implantable supercapacitor in claim 1 in wearable electronic devices, implantable medical devices, intelligent health monitoring systems, and bionic electronic devices.

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