Aerogel microsphere material for carrying lithium sulfide and preparation method

Abstract

The application discloses an aerogel microsphere material used as lithium sulfide loading and a preparation method thereof. The aerogel microsphere is composed of graphene oxide (GO) and in-situ growth carbon nanotube composite porous MXene material doped with complex atoms, and the mass ratio of the two is (1:1) to (1:20).

Description

Technical Field

[0001] This application relates to the field of materials preparation technology, and in particular to an aerogel microsphere material used as a carrier of lithium sulfide and its preparation method. Background Technology

[0002] Lithium-ion batteries have developed rapidly in recent years, but the low specific energy density, insufficient lifespan, and environmental pollution of lithium-ion batteries based on lithium iron phosphate / C and ternary materials / C systems, which are currently widely used, seriously restrict the in-depth application and development of lithium-ion batteries.

[0003] Lithium-sulfur batteries possess high specific capacity and energy density, and sulfur is abundant, making them environmentally friendly and virtually pollution-free. Therefore, lithium-sulfur batteries are considered a very promising type of lithium battery. However, lithium-sulfur batteries have certain problems and drawbacks, such as the shuttle effect of polysulfide compounds, the low conductivity of sulfur, and volume expansion during cycling. Furthermore, lithium dendrites form during cycling, which can cause separator puncture and short circuits, leading to battery safety issues and limiting the practical application of lithium-sulfur battery systems. Lithium sulfide (Li₂S), as a lithiation product of sulfur, is used as a cathode material in lithium-ion batteries. It can provide its own lithium ions, avoiding the use of metallic lithium as the anode, thus effectively eliminating safety hazards. Moreover, lithium sulfide materials are charged before discharging, thus avoiding structural damage caused by volume expansion and achieving better electrochemical performance, making it a highly promising cathode material for lithium-ion batteries. However, lithium sulfide exhibits electron-ion insulation, resulting in lower electrochemical activity for lithium sulfide cathode materials. Moreover, during the charging and discharging process, the dissolution, diffusion, and shuttle effect of polysulfide ions still exist, and the battery will still exhibit severe capacity decay. Summary of the Invention

[0004] The purpose of this application is to provide an aerogel microsphere material for carrying lithium sulfide and a method for its preparation. This aerogel microsphere material employs a multi-component composite structure of graphene, carbon nanotubes, and porous MXene. This structure not only effectively improves the electronic conductivity, loading capacity, and utilization rate of the lithium sulfide cathode active material, but also alleviates the dissolution problem of intermediate polysulfide ions, thereby improving battery cycle stability and enabling high-performance lithium-sulfur batteries.

[0005] According to a first aspect of the present application, an aerogel microsphere material for carrying lithium sulfide is provided, wherein the aerogel microsphere is composed of graphene oxide (GO) and in-situ grown carbon nanotubes composite heteroatom-doped porous MXene material, with a mass ratio of (1:1) to (1:20).

[0006] According to a second aspect of the embodiment of the present application, a method for preparing aerogel microspheres for carrying lithium sulfide is provided, which comprises the following steps:

[0007] Step one, stirring and dispersing MXene nanosheets into a hydrogen peroxide solution, etching by stirring, then centrifuging and washing the reacted solution, and ultrasonic dispersing to obtain a porous MXene nanosheet solution;

[0008] Step two, preparation of a heteroatom dispersion liquid: adding a nitrogen source, a boron source and a phosphorus source into a dispersant, and fully stirring to disperse them uniformly to obtain a heteroatom dispersion liquid;

[0009] Step three, adding the porous MXene nanosheet solution prepared in step one into the heteroatom dispersion liquid prepared in step two, fully stirring until they are mixed uniformly, then centrifuging and drying the mixed liquid to obtain a precursor material;

[0010] Step four, placing the precursor material into a corundum crucible, then transferring it into a tube furnace, heating to a predetermined temperature in a protective atmosphere, keeping the temperature, and then naturally cooling to room temperature, and collecting the solid in the corundum crucible to obtain a porous MXene material doped with heteroatoms;

[0011] Step five, placing ferrocene and the porous MXene material doped with heteroatoms prepared in step four into a mortar, adding an organic dispersant, grinding until they are fully mixed, and then drying to obtain a mixture;

[0012] Step six, placing the mixture prepared in step five into a corundum crucible, uniformly placing an ignition agent on top of the mixture, placing the crucible into a microwave device, collecting the product after microwave irradiation to obtain a porous MXene material doped with heteroatoms and in-situ grown carbon nanotubes;

[0013] Step seven, dissolving the porous MXene material doped with heteroatoms and in-situ grown carbon nanotubes prepared in step six in deionized water, ultrasonic dispersing until they are fully dissolved, then adding graphene oxide (GO), and ultrasonic dispersing until it is fully dissolved to obtain a porous MXene and graphene oxide composite dispersion liquid;

[0014] Step eight, atomizing the dispersion liquid prepared in step seven into droplet microspheres by a spray method, and forming porous MXene and graphene oxide composite ice microspheres in a cooling bath receiving liquid, then freeze-drying the ice microspheres to obtain aerogel microspheres for carrying lithium sulfide.

[0015] Preferably, the porous MXene nanosheets are ceramic materials with a porous two-dimensional sheet structure, and the chemical general formula is M n+1 X n T z , wherein M represents a transition metal, X represents C or / and N, n is 1-3, T zpointing to surface groups, preferably Ti3C2T x .

[0016] Preferably, the heteroatom is one or more of N, B, P, and the molar ratio of the heteroatom:porous MXene nanoplatelets is (1:10) to (1:1), wherein the molar ratio of B:N:P is (0-1):(0-4):(0-4), preferably 1:2:3.

[0017] Preferably, the mass ratio of the MXene nanoplatelets to the hydrogen peroxide solution is 0.1 to 1, and the mass concentration of the hydrogen peroxide solution is 0.01% to 0.1%.

[0018] Preferably, the etching temperature is 20 to 80°C, and the etching time is 10 to 100 min.

[0019] Preferably, the nitrogen source is selected from one or more of ammonium sulfate, nitric acid, urea, and 1-butyl-3-methylimidazolium tetrafluoroborate (BMI-TFB); the boron source is selected from one or more of sodium borohydride, boric acid, and B2H6; and the phosphorus source is selected from one or more of phosphoric acid, sodium hypophosphite, hexafluorophosphoric acid, and ammonium dihydrogen phosphate.

[0020] Preferably, the dispersant is selected from one or more of deionized water and ethanol; and the protective atmosphere is any one or both of argon and nitrogen.

[0021] Preferably, the ferrocene is dicyclopentadiene iron (chemical formula Fe(C5H5)2), and the mass ratio of the ferrocene to the heteroatom-doped porous MXene is (0.5:1) to (1.5:1), preferably 1:1.

[0022] Preferably, the organic dispersant is one or more of toluene, acetone, and dimethyl sulfoxide (dmso), preferably acetone; and the mass ratio of the amount of the organic dispersant to the total amount of the ferrocene and the heteroatom-doped porous MXene is (1:100) to (1:20).

[0023] Preferably, the ignition agent is selected from one or both of carbon powder and carbon fiber, preferably carbon fiber; and the mass ratio of the ignition agent to the mixture is (1:300) to (1:100).

[0024] Preferably, after the precursor material is placed in the corundum crucible in step four, it is transferred to a tube furnace, heated to 200 to 500°C at a temperature rising rate of 3 to 6°C / min in a protective atmosphere, and naturally cooled to room temperature after holding for 1 to 5 hours.

[0025] Preferably, the microwave device has a power of 400-1500W, preferably 900W; the time of each microwave irradiation is 20-80s, preferably 40s; and the number of microwave irradiations is 1-5, preferably 3.

[0026] Preferably, the concentration of the porous MXene and graphene oxide composite dispersion is 1-3%.

[0027] The technical scheme provided by the embodiments of the present application can include the following beneficial effects:

[0028] The preparation method of the present application has the advantages of simple production process, easy control, low cost, green and pollution-free from raw material use to preparation process, and is beneficial to industrial large-scale production.

[0029] The prepared aerogel microspheres also have abundant pores, which is beneficial to increase the specific surface area and adsorb a large amount of lithium sulfide active material to improve the loading rate. The two-dimensional porous MXene material layer can improve the ionic conductivity and electronic conductivity, and accelerate the transmission speed of ions and electrons, thereby improving the reaction kinetics activity of the lithium-sulfur battery. The mutual intercalation and connection of MXene / graphene oxide / carbon nanotubes in the aerogel microsphere structure will form a multi-layer network structure, which is also beneficial to electron transfer.

[0030] The carbon nanotube / graphene oxide has the advantages of good chemical stability, large elastic modulus and high mechanical strength, and forms an interlaced network structure in the electrode, which can provide a buffer zone for the volume expansion of the positive electrode in the cycle process, effectively reduces the stress generated by the volume expansion of the electrode material in the charging and discharging process of the lithium-sulfur battery, and improves the stability of the positive electrode material of the lithium-sulfur battery.

[0031] The prepared aerogel microsphere composite structure can adsorb a large amount of active components, has good physical barrier and chemical adsorption effect on polysulfides generated in the charging and discharging process, thereby reducing the occurrence of the shuttle effect, and improving the rate performance and cycle stability of the lithium-sulfur battery.

[0032] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. DETAILED DESCRIPTION

[0033] The following embodiments clearly and completely describe the technical scheme of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The exemplary embodiments will be described in detail.

[0034] Embodiment 1

[0035] The application relates to a preparation method of aerogel microsphere material loaded with lithium sulfide, and particularly relates to the following steps.

[0036] Step one, preparation of a porous MXene nanosheet solution: 30 parts by weight of Ti3C2T x The nanosheets are stirred and dispersed into 300 parts by weight of a 0.01% hydrogen peroxide (H2O2) solution, and then stirred and etched at 20 DEG C for 10 minutes; then the reacted solution is centrifuged and washed, and ultrasonic dispersion is performed to obtain a porous MXene nanosheet solution.

[0037] Step two, preparation of a heteroatom dispersion liquid: 100 parts by weight of 1% boric acid, wherein the boric source can be replaced by sodium borohydride or B2H6; 100 parts by weight of 1% phosphoric acid, wherein the phosphorus source can be replaced by sodium hypophosphite, hexafluorophosphoric acid or ammonium dihydrogen phosphate; 100 parts by weight of 1% nitric acid, wherein the nitrogen source can be replaced by ammonium sulfate, urea or 1-butyl-3-methylimidazolium tetrafluoroborate; and 300 parts by weight of deionized water are added, and then fully stirred to obtain a heteroatom dispersion liquid.

[0038] Step three, preparation of a precursor material: the porous MXene nanosheet solution prepared in step one is added into the heteroatom dispersion liquid prepared in step two, and then fully stirred until mixed uniformly; then the mixed liquid is centrifuged and dried to obtain a precursor material.

[0039] Step four, preparation of a heteroatom-doped porous MXene material: the precursor material is placed into a corundum crucible, and then transferred into a tube furnace; the temperature is raised to 200 DEG C at a speed of 3 DEG C / min under a protective atmosphere of argon and nitrogen in a ratio of 1:1; after being kept at 200 DEG C for 1 hour, the temperature is naturally cooled to room temperature; and then the solid in the corundum crucible is collected to obtain a heteroatom-doped porous MXene material.

[0040] Step five, preparation of a ferrocene and porous MXene mixture: 10 parts by weight of ferrocene and 20 parts by weight of the heteroatom-doped porous MXene material prepared in step four are placed into a mortar, 0.3 parts by weight of acetone, which can be replaced by toluene or dimethyl sulfoxide (dmso), is added, and then grinding is performed for 5 minutes until fully mixed; and then drying is performed to obtain a ferrocene and porous MXene mixture.

[0041] Step six, preparation of a carbon nanotube in-situ growth composite heteroatom-doped porous MXene material: the mixture prepared in step five is placed into a corundum crucible, 0.1 parts by weight of carbon fiber is uniformly placed on the top of the mixture, and then the crucible is placed into a microwave device; the power is set to 400 W, and the time is set to 20 s; after once microwave irradiation, the product is collected to obtain a carbon nanotube in-situ growth composite heteroatom-doped porous MXene material.

[0042] Step seven, preparation of porous MXene and graphene oxide composite dispersion: take 1 part by weight of the in-situ grown carbon nanotube composite porous MXene material prepared in step six and dissolve it in 200 parts by weight of deionized water, ultrasonic it to fully dissolve, then add 1 part by weight of graphene oxide (GO), ultrasonic it to fully dissolve to obtain a porous MXene and graphene oxide composite dispersion;

[0043] Step eight, preparation of aerogel microsphere material for carrying lithium sulfide: the dispersion prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene oxide composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature lower than -50℃ and a pressure lower than 50Pa, and the porous MXene and graphene oxide composite aerogel microspheres for carrying lithium sulfide are obtained.

[0044] Example 2

[0045] The method for preparing the aerogel microsphere material for carrying lithium sulfide specifically comprises the following steps:

[0046] Step one, preparation of porous MXene nanosheet solution: take 30 parts by weight of Ti3C2T x Nanosheet is stirred and dispersed into 60 parts by weight of 0.05% mass concentration hydrogen peroxide (H2O2) solution, stirred and etched at 50℃ for 50 minutes, then the reacted solution is centrifuged and washed, and ultrasonic dispersed to obtain a porous MXene nanosheet solution.

[0047] Step two, preparation of heteroatom dispersion: take 100 parts by weight of 1% concentration boric acid, which can be replaced by one or more of sodium borohydride and B2H6, and add 100 parts by weight of deionized water, fully stir to obtain a heteroatom dispersion.

[0048] Step three, preparation of precursor material: add the porous MXene nanosheet solution prepared in step one to the heteroatom dispersion prepared in step two, fully stir until mixed evenly, then centrifuge the mixed solution and dry to obtain a precursor material.

[0049] Step four, preparation of heteroatom-doped porous MXene material: place the precursor material in a corundum crucible, then transfer it to a tube furnace, heat it to 400℃ at a temperature rising speed of 5℃ / min in a nitrogen protective atmosphere. After holding for 3 hours, naturally cool it to room temperature, collect the solid in the corundum crucible, and the heteroatom-doped porous MXene material is obtained.

[0050] Step five, preparation of ferrocene and porous MXene mixture: take 10 parts by weight of ferrocene and 10 parts by weight of heteroatom-doped porous MXene material prepared in step four and place them in a mortar, add 0.4 parts by weight of acetone, which can be replaced by toluene or dimethyl sulfoxide (dmso); grind for 8 minutes to fully mix, then dry to obtain a ferrocene and porous MXene mixture;

[0051] Step six, preparation of in-situ grown carbon nanotube composite heteroatom-doped porous MXene material: place the mixture prepared in step five in a corundum crucible, evenly spread 0.1 parts by weight of carbon fiber on top, place the crucible in a microwave device, set the power to 900W and the time to 40s, after 3 times of microwave irradiation, collect the product, which is the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material.

[0052] Step seven, preparation of porous MXene and graphene oxide composite dispersion: take 10 parts by weight of the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material prepared in step six and dissolve it in 500 parts by weight of deionized water, ultrasonic to fully dissolve, then add 1 part by weight of graphene oxide (GO), ultrasonic to fully dissolve to obtain a porous MXene and graphene oxide composite dispersion;

[0053] Step eight, preparation of aerogel microsphere material for carrying lithium sulfide: the dispersion prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene oxide composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature below -50℃ and a pressure below 50Pa, and the porous MXene and graphene oxide composite aerogel microspheres for carrying lithium sulfide are obtained.

[0054] Example 3

[0055] The method for preparing the aerogel microsphere material for carrying lithium sulfide specifically includes the following steps:

[0056] Step one, preparation of porous MXene nanosheet solution: take 9 parts by weight of Ti3C2T x nanosheets and stir and disperse them into 9 parts by weight of a 0.1% mass concentration hydrogen peroxide (H2O2) solution, stir and etch at 80℃ for 100 minutes, then centrifuge and wash the reacted solution, and ultrasonic disperse to obtain a porous MXene nanosheet solution.

[0057] Step two, preparation of heteroatom dispersion: the nitrogen source can be replaced by ammonium sulfate, nitric acid, urea, 1-butyl-3-methylimidazolium tetrafluoroborate, add 100 parts by weight of deionized water, and fully stir to obtain a heteroatom dispersion.

[0058] Step three, precursor material preparation: the porous MXene nanosheet solution prepared in step one is added to the heteroatom dispersion prepared in step two, and after stirring thoroughly to mix evenly, the mixture is centrifuged and dried to obtain the precursor material.

[0059] Step four, preparation of heteroatom-doped porous MXene material: the precursor material is placed in a corundum crucible and then transferred to a tube furnace, and heated to 500℃ at a heating rate of 6℃ / min in an argon protective atmosphere. After 5 hours of heat preservation, it is naturally cooled to room temperature, and the solid in the corundum crucible is collected, which is the heteroatom-doped porous MXene material.

[0060] Step five, preparation of ferrocene and porous MXene mixture: 10 parts by weight of ferrocene and 5 parts by weight of heteroatom-doped porous MXene material prepared in step four are placed in a mortar, 0.75 parts by weight of acetone, which can be replaced by toluene or dimethyl sulfoxide (dmso), is added, and grinding for 10 minutes to mix thoroughly, and then drying to obtain the ferrocene and porous MXene mixture;

[0061] Step six, preparation of in-situ grown carbon nanotube composite heteroatom-doped porous MXene material: the mixture prepared in step five above is placed in a corundum crucible, 0.15 parts by weight of carbon fiber is uniformly placed on top, and the crucible is placed in a microwave device, with a power of 1500W and a time of 80s. After 5 times of microwave irradiation, the product is collected, which is the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material.

[0062] Step seven, preparation of porous MXene and graphene oxide composite dispersion: 20 parts by weight of the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material prepared in step six is dissolved in 150 parts by weight of deionized water, ultrasonic treatment is performed to fully dissolve it, and then 1 part by weight of graphene oxide (GO) is added and ultrasonic treatment is performed to fully dissolve it to obtain the porous MXene and graphene oxide composite dispersion;

[0063] Step eight, preparation of aerogel microsphere material for carrying lithium sulfide: the dispersion prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene oxide composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature below -50℃ and a pressure below 50Pa to obtain the porous MXene and graphene oxide composite aerogel microspheres for carrying lithium sulfide.

[0064] Example 4

[0065] The method for preparing the aerogel microsphere material for carrying lithium sulfide specifically includes the following steps:

[0066] Step one, preparation of porous MXene nanosheet solution: 20 parts by weight of Ti3C2T x The nanosheets were stirred and dispersed in a 200 parts by weight of 0.01% mass concentration hydrogen peroxide (H2O2) solution, stirred and etched at 20°C for 10 minutes, then the reacted solution was centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution.

[0067] Step two, preparation of heteroatom dispersion liquid: 100 parts by weight of 1% concentration phosphoric acid, the phosphorus source can be replaced with sodium hypophosphite, hexafluorophosphoric acid, ammonium dihydrogen phosphate, 100 parts by weight of deionized water, fully stirred to obtain a heteroatom dispersion liquid.

[0068] Step three, preparation of precursor material: the porous MXene nanosheet solution prepared in step one is added to the heteroatom dispersion liquid prepared in step two, fully stirred until mixed evenly, then the mixture is centrifuged and dried to obtain a precursor material.

[0069] Step four, preparation of heteroatom-doped porous MXene material: the precursor material is placed in a corundum crucible and transferred to a tube furnace, heated to 200°C at a heating rate of 3°C / min in a nitrogen protective atmosphere. After 1 hour of heat preservation, it is naturally cooled to room temperature, and the solid in the corundum crucible is collected to obtain a heteroatom-doped porous MXene material.

[0070] Step five, preparation of ferrocene and porous MXene mixture: 10 parts by weight of ferrocene and 20 parts by weight of heteroatom-doped porous MXene material prepared in step four are placed in a mortar, 0.3 parts by weight of acetone, which can be replaced by toluene or dimethyl sulfoxide (dmso), is added, and the mixture is ground for 5 minutes until fully mixed, then dried to obtain a ferrocene and porous MXene mixture;

[0071] Step six, preparation of in-situ grown carbon nanotube composite heteroatom-doped porous MXene material: the mixture prepared in step five is placed in a corundum crucible, 0.1 parts by weight of carbon fiber is evenly placed on top, the crucible is placed in a microwave device, the power is set to 400W and the time is set to 20s, after 1 time of microwave irradiation, the product is collected to obtain an in-situ grown carbon nanotube composite heteroatom-doped porous MXene material.

[0072] Step seven, preparation of porous MXene and graphene oxide composite dispersion liquid: 1 part by weight of in-situ grown carbon nanotube composite heteroatom-doped porous MXene material prepared in step six is dissolved in 200 parts by weight of deionized water, ultrasonically dissolved to obtain a porous MXene and graphene oxide composite dispersion liquid;

[0073] Step eight, preparation of aerogel microspheres for carrying lithium sulfide: the dispersion liquid prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene oxide composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature below -50℃ and a pressure below 50 Pa, and porous MXene and graphene oxide composite aerogel microspheres for carrying lithium sulfide are obtained.

[0074] Example 5

[0075] The preparation method of the aerogel microspheres for carrying lithium sulfide specifically includes the following steps:

[0076] Step one, preparation of a porous MXene nanosheet solution: 20 parts by weight of Ti3C2T x nanosheets are stirred and dispersed in 40 parts by weight of a 0.05% mass concentration hydrogen peroxide (H2O2) solution, etched at 50℃ for 50 minutes, and then the reacted solution is centrifuged, washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution.

[0077] Step two, preparation of a heteroatom dispersion liquid:

[0078] Take 100 parts by weight of 1% concentration boric acid, and the boron source can be replaced with sodium borohydride, B2H6; 100 parts by weight of 1% concentration phosphoric acid, and the phosphorus source can be replaced with sodium hypophosphite, hexafluorophosphoric acid, and ammonium dihydrogen phosphate; add 200 parts by weight of deionized water, and fully stir to obtain a heteroatom dispersion liquid.

[0079] Step three, preparation of a precursor material: the porous MXene nanosheet solution prepared in step one is added to the heteroatom dispersion liquid prepared in step two, and after fully stirring to mix uniformly, the mixture is centrifuged and dried to obtain a precursor material.

[0080] Step four, preparation of a heteroatom-doped porous MXene material: the precursor material is placed in a corundum crucible and then transferred to a tube furnace, heated to 400℃ at a temperature increasing rate of 5℃ / min in an argon protective atmosphere. After holding for 3 hours, it is naturally cooled to room temperature, and the solid in the corundum crucible is collected to obtain a heteroatom-doped porous MXene material.

[0081] Step five, preparation of a ferrocene and porous MXene mixture: 10 parts by weight of ferrocene and 10 parts by weight of the heteroatom-doped porous MXene material prepared in step four are placed in a mortar, 0.4 parts by weight of dimethyl sulfoxide, which can be replaced with acetone or toluene, is added, and grinding is performed for 8 minutes until fully mixed, and then dried to obtain a ferrocene and porous MXene mixture;

[0082] Step six, preparation of in-situ grown carbon nanotube composite complex atom doped porous MXene material: place the mixture prepared in step five in a corundum crucible, evenly spread 0.1 parts by weight of carbon fiber on top, place the crucible in a microwave device, set the power to 900W and the time to 40s, collect the product after 3 times of microwave irradiation, and in-situ grown carbon nanotube composite complex atom doped porous MXene material is obtained.

[0083] Step seven, preparation of porous MXene and graphene oxide composite dispersion: 10 parts by weight of in-situ grown carbon nanotube composite complex atom doped porous MXene material prepared in step six is dissolved in 500 parts by weight of deionized water, ultrasonic is used to make it fully dissolved, then 1 part by weight of graphene oxide (GO) is added, ultrasonic is used to make it fully dissolved to obtain a porous MXene and graphene oxide composite dispersion.

[0084] Step eight, preparation of aerogel microsphere material for carrying lithium sulfide: the dispersion prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene oxide composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature lower than -50℃ and a pressure lower than 50Pa, and the porous MXene and graphene oxide composite aerogel microspheres for carrying lithium sulfide are obtained.

[0085] Example 6

[0086] The method for preparing the aerogel microsphere material for carrying lithium sulfide specifically includes the following steps:

[0087] Step one, preparation of porous MXene nanosheet solution: 5 parts by weight of Ti3C2T x nanosheets are stirred and dispersed into 5 parts by weight of 0.1% hydrogen peroxide (H2O2) solution, etched at 80℃ for 100 minutes, then the reacted solution is centrifuged and washed, and ultrasonic dispersion is used to obtain a porous MXene nanosheet solution.

[0088] Step two, preparation of heteroatom dispersion: 100 parts by weight of 1% phosphoric acid, the phosphorus source can be replaced with sodium hypophosphite, hexafluorophosphoric acid, ammonium dihydrogen phosphate; 100 parts by weight of 1% nitric acid, the nitrogen source can be replaced with ammonium sulfate, urea, 1-butyl-3-methylimidazolium tetrafluoroborate; 200 parts by weight of deionized water is added, and the mixture is stirred uniformly to obtain a heteroatom dispersion. Step three, preparation of precursor material: the porous MXene nanosheet solution prepared in step one is added to the heteroatom dispersion prepared in step two, and the mixture is stirred uniformly, then the mixture is centrifuged and dried to obtain a precursor material.

[0089] Step four, preparation of the heteroatom-doped porous MXene material: After the precursor material is placed in a corundum crucible, it is transferred to a tube furnace and heated to 500°C at a heating rate of 6°C / min in an argon protective atmosphere. After holding for 5 hours, it is naturally cooled to room temperature, and the solid in the corundum crucible is collected, thereby obtaining the heteroatom-doped porous MXene material.

[0090] Step five, preparation of the ferrocene and porous MXene mixture: 10 parts by weight of ferrocene and 5 parts by weight of the heteroatom-doped porous MXene material prepared in step four are placed in a mortar, 0.75 parts by weight of toluene, which can be replaced by acetone or dimethyl sulfoxide, is added, and grinding is performed for 10 minutes until the mixture is fully mixed, and then drying is performed, thereby obtaining the ferrocene and porous MXene mixture.

[0091] Step six, preparation of the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material: the mixture prepared in step five above is placed in a corundum crucible, 0.15 parts by weight of carbon fibers are uniformly placed on top, the crucible is placed in a microwave device, a power of 1500W and a time of 80s are set, and after 5 times of microwave irradiation, the product is collected, thereby obtaining the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material.

[0092] Step seven, preparation of the porous MXene and graphene oxide composite dispersion: 20 parts by weight of the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material prepared in step six is dissolved in 150 parts by weight of deionized water, ultrasonic treatment is performed until it is fully dissolved, 1 part by weight of graphene oxide (GO) is added, and ultrasonic treatment is performed until it is fully dissolved, thereby obtaining the porous MXene and graphene oxide composite dispersion.

[0093] Step eight, preparation of the aerogel microsphere material for carrying lithium sulfide: the dispersion prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature lower than -50°C and a pressure lower than 50Pa, thereby obtaining the porous MXene and graphene composite aerogel microspheres for carrying lithium sulfide.

[0094] Example 7

[0095] The method for preparing the aerogel microsphere material for carrying lithium sulfide specifically includes the following steps:

[0096] Step one, preparation of the porous MXene nanosheet solution: 10 parts by weight of Ti3C2T x nanosheets are stirred and dispersed into 100 parts by weight of a 0.01% hydrogen peroxide (H2O2) solution, stirring and etching are performed at 20°C for 10 minutes, and then the reacted solution is centrifuged and washed, and ultrasonic dispersion is performed, thereby obtaining the porous MXene nanosheet solution.

[0097] Step two, preparation of heteroatom dispersion liquid: take 100 parts by weight of 1% concentration of boric acid, the boron source can be replaced with sodium borohydride, B2H6; 100 parts by weight of 1% concentration of nitric acid, the nitrogen source can be replaced with ammonium sulfate, urea, 1-butyl-3-methylimidazolium tetrafluoroborate; add 200 parts by weight of deionized water, fully stir to obtain a heteroatom dispersion liquid. Step three, preparation of precursor material: add the porous MXene nanosheet solution prepared in step one to the heteroatom dispersion liquid prepared in step two, fully stir until mixed evenly, then centrifuge the mixture and dry to obtain a precursor material.

[0098] Step four, preparation of heteroatom-doped porous MXene material: place the precursor material into a corundum crucible, then transfer it to a tube furnace, heat to 200°C at a heating rate of 3°C / min in a nitrogen protective atmosphere. After 1 hour of heat preservation, naturally cool to room temperature, collect the solid in the corundum crucible, and the heteroatom-doped porous MXene material is obtained.

[0099] Step five, preparation of ferrocene and porous MXene mixture: take 10 parts by weight of ferrocene and 20 parts by weight of heteroatom-doped porous MXene material prepared in step four, place them in a mortar, add 0.3 parts by weight of acetone, which can be replaced with toluene or dimethyl sulfoxide, grind for 5 minutes until fully mixed, then dry to obtain a ferrocene and porous MXene mixture;

[0100] Step six, preparation of in-situ grown carbon nanotube composite heteroatom-doped porous MXene material: place the mixture prepared in step five in a corundum crucible, evenly spread 0.1 parts by weight of carbon fiber on top, place the crucible in a microwave device, set the power to 400W and the time to 20s, collect the product after 1 time of microwave irradiation, and the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material is obtained.

[0101] Step seven, preparation of porous MXene and graphene oxide composite dispersion liquid: take 1 part by weight of the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material prepared in step six, dissolve it in 200 parts by weight of deionized water, ultrasonic to fully dissolve, then add 1 part by weight of graphene oxide (GO), ultrasonic to fully dissolve to obtain a porous MXene and graphene oxide composite dispersion liquid;

[0102] Step eight, preparation of aerogel microspheres for carrying lithium sulfide: the dispersion prepared in step seven is atomized into droplet microspheres by a spray method, and porous MXene and graphene oxide composite ice microspheres are formed in a cooling bath receiving liquid. Subsequently, the ice microspheres are freeze-dried in an environment with a temperature below -50°C and a pressure below 50 Pa, and porous MXene and graphene oxide composite aerogel microspheres for carrying lithium sulfide are obtained.

[0103] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0104] It is to be understood that the application is not limited to the precise details of construction described above and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application should only be limited by the appended claims.

Claims

1. A method for preparing aerogel microspheres used as lithium sulfide-loaded materials, characterized in that: The aerogel microspheres are composed of graphene oxide and in-situ grown carbon nanotubes combined with heteroatom-doped porous MXene material, with a mass ratio of (1:1) to (1:20). The preparation method includes: Step 1: Take MXene nanosheets and stir them into hydrogen peroxide solution. Stir and etch the solution. Then, centrifuge and wash the solution after the reaction, and ultrasonically disperse it to obtain a porous MXene nanosheet solution. Step 2, Preparation of heteroatom dispersion: Nitrogen source, boron source and phosphorus source are added to the dispersant and stirred thoroughly to disperse them evenly, thus obtaining heteroatom dispersion; Step 3: Add the porous MXene nanosheet solution obtained in Step 1 to the heteroatom dispersion obtained in Step 2, stir thoroughly until homogeneous, centrifuge and dry the mixture to obtain the precursor material. Step 4: After placing the precursor material into the corundum crucible, transfer it to a tube furnace, heat it to a predetermined temperature in a protective atmosphere, hold it at that temperature, and then allow it to cool naturally to room temperature. Collect the solid in the corundum crucible to obtain the heteroatom-doped porous MXene material. Step 5: Place ferrocene and the heteroatom-doped porous MXene material prepared in Step 4 into a mortar, add an organic dispersant, grind until fully mixed, and then dry to obtain the mixture; Step 6: Place the mixture prepared in step 5 into a corundum crucible, spread the igniter evenly on the top, place the crucible into a microwave device, collect the product after microwave radiation, and obtain the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material. Step 7: Dissolve the in-situ grown carbon nanotube composite heteroatom-doped porous MXene material prepared in Step 6 in deionized water, sonicate it to dissolve completely, then add graphene oxide and sonicate it to dissolve completely to obtain a porous MXene and graphene oxide composite dispersion. Step 8: The dispersion prepared in Step 7 is atomized into droplet microspheres by spraying, and porous MXene and graphene oxide composite ice microspheres are formed in the receiving liquid of the cooling bath. The ice microspheres are then freeze-dried to obtain the aerogel microsphere material used to carry lithium sulfide.

2. The preparation method according to claim 1, characterized in that: porous MXene nanosheets are porous two-dimensional layered ceramic materials with the general chemical formula M. n+1 X n T z Where M refers to a transition metal, X refers to C and / or N, n is 1-3, and T z Refers to surface groups.

3. The preparation method according to claim 2, characterized in that: porous MXene nanosheets are Ti3C2T x .

4. The preparation method according to claim 1, characterized in that: The heteroatoms are N, B, and P, and the molar ratio of heteroatoms to porous MXene nanosheets is (1:10) to (1:1), wherein the molar ratio of B:N:P is (0 to 1):(0 to 4):(0 to 4).

5. The preparation method according to claim 4, characterized in that: The molar ratio of B:N:P is 1:2:

3.

6. The preparation method according to claim 1, characterized in that: The mass ratio of MXene nanosheets to hydrogen peroxide solution is 0.1–1, and the mass concentration of hydrogen peroxide solution is 0.01%–0.1%.

7. The preparation method according to claim 1, characterized in that: The etching temperature is 20–80℃, and the etching time is 10–100 min.

8. The preparation method according to claim 1, characterized in that: The nitrogen source is selected from one or more of ammonium sulfate, nitric acid, urea, and 1-butyl-3-methylimidazolium tetrafluoroborate; the boron source is selected from one or more of sodium borohydride, boric acid, and B2H6; and the phosphorus source is selected from one or more of phosphoric acid, sodium hypophosphite, hexafluorophosphate, and ammonium dihydrogen phosphate.

9. The preparation method according to claim 1, characterized in that: The dispersant is selected from one or more of deionized water and ethanol; the protective atmosphere is any one or both of argon and nitrogen.

10. The preparation method according to claim 1, characterized in that: The ferrocene is dicyclopentadiene iron, and the mass ratio of ferrocene to heteroatom-doped porous MXene is (0.5:1) to (1.5:1).

11. The preparation method according to claim 10, characterized in that: The mass ratio of ferrocene to heteroatom-doped porous MXene is 1:

1.

12. The preparation method according to claim 1, characterized in that: The organic dispersant is one or more of toluene, acetone, and dimethyl sulfoxide; the mass ratio of the amount of organic dispersant to the total amount of ferrocene and heteroatom-doped porous MXene is (1:100) to (1:20).

13. The preparation method according to claim 12, characterized in that: The organic dispersant is acetone.

14. The preparation method according to claim 1, characterized in that: The igniter is selected from one or two of carbon powder or carbon fiber; the mass ratio of igniter to mixture is (1:300) to (1:100).

15. The preparation method according to claim 14, characterized in that: The igniter is carbon fiber.

16. The preparation method according to claim 1, characterized in that: In step four, after placing the precursor material into the corundum crucible, it is transferred to a tube furnace and heated to 200-500°C at a heating rate of 3-6°C / min in a protective atmosphere. After holding at this temperature for 1-5 hours, it is naturally cooled to room temperature. The power of the microwave device is 400-1500W; the duration of each microwave radiation session is 20-80 seconds; and the number of microwave radiation sessions is 1-5.

17. The preparation method according to claim 16, characterized in that: The microwave device has a power of 900W; each microwave radiation session lasts for 40 seconds; and the number of microwave radiation sessions is 3.

18. The preparation method according to claim 1, characterized in that: The concentration of the porous MXene and graphene oxide composite dispersion is 1% to 3%.