CN114079040B - Preparation method and application of scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for potassium-sulfur battery - Google Patents

Preparation method and application of scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for potassium-sulfur battery Download PDF

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CN114079040B
CN114079040B CN202111238756.6A CN202111238756A CN114079040B CN 114079040 B CN114079040 B CN 114079040B CN 202111238756 A CN202111238756 A CN 202111238756A CN 114079040 B CN114079040 B CN 114079040B
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CN114079040A (en
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蔡克迪
王坦
郎笑石
姚传刚
奚雪
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Bohai University
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    • H—ELECTRICITY
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Abstract

The invention discloses a preparation method and application of a scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for a potassium-sulfur battery, wherein unique scaly carbon is prepared by a simple and efficient thermal decomposition method, and Mo@TiO is prepared by a simple and easily available sol-gel method and a one-step hydrothermal method 2 By regulating N@C and Mo@TiO 2 Is used for constructing unique scaly N@C/Mo@TiO 2 Double adsorption of polysulfide by composite material, under the influence of synergistic effect, combination of scaly nitrogen doped carbon and Mo@TiO 2 The method has the advantages of high-efficiency physical and chemical adsorption of polysulfide, inhibition of shuttle effect, simple and novel process, low cost, rapid preparation, further improvement of electrochemical performance of the battery and provision of a promising strategy for development of potassium-sulfur batteries and other energy storage devices.

Description

Preparation method and application of scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for potassium-sulfur battery
Technical Field
The invention relates to the technical field of composite electrode material preparation, in particular to a preparation method and application of a scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for a potassium-sulfur battery.
Background
The energy source is closely related to the survival and development of human beings, and is a key problem in the development of world economy. Therefore, the search and development of new renewable energy sources that are environmentally friendly has attracted attention. Lithium ion batteries are free of many harmful metals and possess high energy density and are widely used, however lithium resources are scarce and unevenly distributed greatly increase the cost problems in the preparation process and seriously hinder industrial production. At present, one of brothers of alkali metals, namely potassium element, is widely paid attention to in academia, and is the first main group element, so that the potassium element is rich in resources in the crust, uniformly distributed, low in cost, fast in ion conduction in electrolyte and has high potential similar to lithium.
The potassium-sulfur battery generally refers to a battery in which a sulfur-containing substance is used as a positive electrode and metallic potassium is used as a negative electrode, and the electrolyte is generally an ether electrolyte containing an additive, an organogel electrolyte, or the like. In the charge and discharge process, the metal potassium and the elemental sulfur generate chemical reaction through electron loss and electron loss, so that an external circuit is promoted to form current to realize energy storage and release. However, the intermediate potassium polysulfide is easily dissolved in the electrolyte during the discharge process, and the potassium polysulfide passes through the diaphragm under the dual actions of concentration gradient and electric field gradient to produce a shuttle effect, so that the loss of active substances and the corrosion and passivation of potassium metal are caused. So that the corrosion of the negative electrode potassium is serious, the battery capacity and the coulomb efficiency are reduced, and the battery performance is seriously affected. Therefore, it is important to prepare a host material that efficiently adsorbs potassium polysulfide and has high conductivity.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a preparation method and application of a scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for a potassium-sulfur battery, which are influenced by a synergistic effect, and the scaly nitrogen-doped carbon and Mo@TiO2 are combined to efficiently physically and chemically adsorb polysulfide to inhibit the generation of a shuttle effect, and the preparation method is simple and novel in process, low in cost and capable of being rapidly prepared, so that the problems in the background art are solved.
In order to achieve the above purpose, the present invention provides the following technical solutions: a preparation method of a scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for a potassium-sulfur battery comprises the following steps:
s1, weighing a proper amount of polyvinylpyrrolidone, carbonizing for a period of time at a high temperature in a high-purity nitrogen atmosphere, then performing annealing treatment at a speed of 1-3 ℃/min, grinding, and then performing sterilization treatment to obtain a scaly nitrogen-doped carbon material;
s2, dropwise adding absolute ethyl alcohol into the mixed solution of tetrabutyl titanate and concentrated hydrochloric acid, and continuously stirring for a period of time to obtain TiO 2 A precursor solution;
s3, evenly mixing deionized water and concentrated hydrochloric acid in a volume ratio of 10:1-5:1, and then adding the mixture according to TiO 2 TiO in precursor solution 2 Quality of (A) molybdic acid tetrahydrateWeighing ammonium molybdate tetrahydrate powder with the mass ratio of ammonium being 10:1-1:1, and continuously stirring for 1-4 hours to obtain an ammonium molybdate solution;
s4, adding the scaly nitrogen-doped carbon material obtained in the step S1 and the ammonium molybdate solution obtained in the step S3 into the TiO obtained in the step S2 2 Continuously stirring the precursor solution for 8 to 20 hours, uniformly mixing, and carrying out hydrothermal reaction in a hydrothermal kettle at the temperature of between 100 and 200 ℃ for 8 to 32 hours;
s5, placing the material obtained in the step S4 into a drying oven for drying, and grinding to obtain N@C/Mo@TiO 2 A composite powder material;
s6, N@C/Mo@TiO synthesized in step S5 2 Adding sulfur powder into the composite powder material, heating and preserving heat for 15-30 hours at 120-180 ℃ to obtain N@C/Mo@TiO 2 and/S composite positive electrode material.
Preferably, the high-temperature carbonization temperature in the step S1 is 400-1000 ℃; the high-temperature carbonization time is 2-10 h.
Preferably, in the step S2, the volume ratio of the tetrabutyl titanate to the concentrated hydrochloric acid is 12:1-2:1; the volume ratio of tetrabutyl titanate to absolute ethyl alcohol is 1:2-1:4.
Preferably, the drop velocity of the absolute ethyl alcohol in the step S2 is 3 mL/min-6 mL/min; the continuous stirring period is 8-24 hours.
Preferably, in the step S4, tiO 2 TiO in precursor solution 2 The mass ratio of the ammonium molybdate to the ammonium molybdate added to the ammonium molybdate solution is 5:1; tiO (titanium dioxide) 2 TiO in precursor solution 2 The mass ratio of the added scale-shaped nitrogen-doped carbon material is 8:1-1:1.
Preferably, in the step S5, the drying temperature is 60-90 ℃ and the drying time is 8-20 hours.
Preferably, in the step S6, N@C/Mo@TiO 2 The mass ratio of the composite powder material to the sulfur powder is 1:3.
Preferably, the concentration of the concentrated hydrochloric acid is 36%.
In addition, in order to achieve the aim, the invention also provides a scaly nitrogen-doped carbon composite molybdenum dopedApplication of mixed titanium dioxide-sulfur electrode composite positive electrode material as positive electrode plate of potassium-sulfur battery to prepare scaly N@C/Mo@TiO 2 Mixing the S composite positive electrode material, the conductive carbon black and the polyvinylidene fluoride according to the mass ratio of 7:2:1, adding N-methyl pyrrolidone, stirring into uniform paste, coating the paste on the surface of an aluminum foil with the thickness of 15 mu m, coating the thickness of 0.05mm, and then vacuum drying by using a vacuum drying oven to obtain scaly N@C/Mo@TiO 2 And S composite electrode plate.
Preferably, the vacuum drying temperature is 50-90 ℃; the drying time is 12-24 hours.
The beneficial effects of the invention are as follows:
1) The unique scaly carbon is prepared by a simple and efficient thermal decomposition method, has large and rough specific surface area, can provide a large number of active sites and efficiently and physically adsorbs polysulfide.
2) Mo@TiO is prepared by a simple and easily available sol-gel method and a one-step hydrothermal method 2 On the one hand, the doping of Mo atoms increases the grain size and is K of large particles + Providing a transmission channel to accelerate ion diffusion; on the other hand, polar Ti-O bond can chemically adsorb polysulfide, so that the shuttle effect is effectively inhibited.
3) By regulating N@C and Mo@TiO 2 Is used for constructing unique scaly N@C/Mo@TiO 2 The composite material double adsorbs polysulfide, and the assembled potassium-sulfur battery exhibits good compatibility with potassium anode, and has high capacity retention and cycle life.
Drawings
FIG. 1 is a scale-like N@C/Mo@TiO of examples 1-3 2 Assembling the S composite electrode to obtain a charge-discharge curve graph of the potassium-sulfur battery;
FIG. 2 is a scale-like N@C/Mo@TiO of examples 1-3 2 Assembling the S composite electrode to obtain a cyclic voltammogram of the potassium-sulfur battery;
FIG. 3 is a scale-like N@C/Mo@TiO prepared in example 1 2 XRD pattern of S composite positive electrode material;
FIG. 4 is a high-magnification, low-magnification scanning electron microscope photograph of the nitrogen-doped carbon material prepared in the step of example 1, FIG. 4 (a) being high magnification, and FIG. 4 (b) being low magnification;
FIG. 5 is a scale-like N@C/Mo@TiO prepared in the step of example 1 2 High-magnification and low-magnification scanning electron micrographs of the/S composite positive electrode material are shown in FIG. 5 (a) and FIG. 5 (b).
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1-5, the present invention provides a technical solution: a preparation method of a scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for a potassium-sulfur battery comprises the following steps:
s1, weighing a proper amount of polyvinylpyrrolidone, carbonizing for a period of time at a high temperature in a high-purity nitrogen atmosphere, then performing annealing treatment at a speed of 1-3 ℃/min, grinding, and then performing sterilization treatment to obtain a scaly nitrogen-doped carbon material;
s2, dropwise adding absolute ethyl alcohol into the mixed solution of tetrabutyl titanate and concentrated hydrochloric acid, and continuously stirring for a period of time to obtain TiO 2 A precursor solution;
s3, evenly mixing deionized water and concentrated hydrochloric acid in a volume ratio of 10:1-5:1, and then adding the mixture according to TiO 2 TiO in precursor solution 2 The mass ratio of the ammonium molybdate tetrahydrate to the ammonium molybdate tetrahydrate is 10:1-1:1, and stirring is carried out for 1-4 hours to obtain an ammonium molybdate solution;
s4, adding the scaly nitrogen-doped carbon material obtained in the step S1 and the ammonium molybdate solution obtained in the step S3 into the TiO obtained in the step S2 2 Continuously stirring the precursor solution for 8 to 20 hours, uniformly mixing, and carrying out hydrothermal reaction in a hydrothermal kettle at the temperature of between 100 and 200 ℃ for 8 to 32 hours;
s5, placing the material obtained in the step S4 into a drying oven for drying, and grinding to obtainTo N@C/Mo@TiO 2 A composite powder material;
s6, N@C/Mo@TiO synthesized in step S5 2 Adding sulfur powder into the composite powder material, heating and preserving heat for 15-30 hours at 120-180 ℃ to obtain N@C/Mo@TiO 2 and/S composite positive electrode material.
Preferably, the high-temperature carbonization temperature in the step S1 is 400-1000 ℃; the high-temperature carbonization time is 2-10 h.
Further, in the step S2, the volume ratio of the tetrabutyl titanate to the concentrated hydrochloric acid is 12:1-2:1; the volume ratio of tetrabutyl titanate to absolute ethyl alcohol is 1:2-1:4.
Further, the dropping speed of the absolute ethyl alcohol in the step S2 is 3 mL/min-6 mL/min; the continuous stirring period is 8-24 hours.
Further, in the step S4, tiO 2 TiO in precursor solution 2 The mass ratio of the ammonium molybdate to the ammonium molybdate added to the ammonium molybdate solution is 5:1; tiO (titanium dioxide) 2 TiO in precursor solution 2 The mass ratio of the added scale-shaped nitrogen-doped carbon material is 8:1-1:1.
Further, in the step S5, the drying temperature is 60-90 ℃ and the drying time is 8-20 hours.
Further, in the step S6, N@C/Mo@TiO 2 The mass ratio of the composite powder material to the sulfur powder is 1:3.
Further, the concentration of the concentrated hydrochloric acid is 36%.
The invention also provides an application of the scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode composite positive electrode material as a positive electrode plate of a potassium-sulfur battery, wherein the scaly N@C/Mo@TiO is prepared 2 Mixing the S composite positive electrode material, the conductive carbon black and the polyvinylidene fluoride according to the mass ratio of 7:2:1, adding N-methyl pyrrolidone, stirring into uniform paste, coating the paste on the surface of an aluminum foil with the thickness of 15 mu m, coating the thickness of 0.05mm, and then vacuum drying by using a vacuum drying oven to obtain scaly N@C/Mo@TiO 2 And S composite electrode plate.
Further, the vacuum drying temperature is 50-90 ℃; the drying time is 12-24 hours.
Example 1
(1) Scaly N@C/Mo@TiO 2 Preparation of/S composite electrode material
Weighing 2g of polyvinylpyrrolidone, carbonizing at 400 ℃ for 10 hours under the atmosphere of high-purity nitrogen at high temperature, then annealing at 1 ℃/min, grinding, and then placing into an autoclave for sterilization treatment to obtain the scaly nitrogen-doped carbon material; with 3mL of tetrabutyl titanate (C) 16 H 36 O 4 Ti), 0.25mL of 36% concentrated hydrochloric acid (HCl), 0.5mL of absolute ethanol (C) 2 H 6 O) to prepare C 16 H 36 O 4 Ti/HCl/C 2 H 6 The mixed solution of O is stirred continuously for 8 hours to obtain stable and uniform TiO 2 A precursor solution; 10mL of deionized water and 1mL of concentrated hydrochloric acid were uniformly mixed, followed by the addition of 0.08g of ammonium molybdate tetrahydrate ((NH) 4 ) 6 Mo 7 O 24 ·4H 2 O), continuously stirring for 1h to obtain a clear ammonium molybdate solution; weighing 0.1g of scale-shaped nitrogen-doped carbon material, adding the prepared ammonium molybdate solution into TiO 2 Continuously stirring the precursor solution for 8 hours, uniformly mixing, performing hydrothermal reaction in a hydrothermal kettle at 100 ℃ for 8 hours, putting the synthesized material into a drying box, drying at 60 ℃ for 8 hours, and grinding to obtain N@C/Mo@TiO 2 A composite material;
to be synthesized N@C/Mo@TiO 2 Adding sulfur powder into the composite material to make the mass ratio of the sulfur powder to the composite material be 1:3, heating and preserving heat for 15 hours at 120 ℃ to obtain N@C/Mo@TiO 2 and/S composite positive electrode material.
(2) Application of scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode composite positive electrode material as positive electrode plate of potassium-sulfur battery
N@C/Mo@TiO 2 Mixing the composite positive electrode material, conductive carbon black (Super-P) and polyvinylidene fluoride (Polyvinylidene Fluoride) according to the mass ratio of 7:2:1, regulating the viscosity degree to be uniform paste by using proper amount of N-methyl pyrrolidone (NMP), rapidly and uniformly coating one side of the obtained active substance slurry on the surface of an aluminum foil with the thickness of 15 mu m by using a clean blade, coating the thickness of 0.05mm, and then vacuum drying for 12 hours at 50 ℃ by using a vacuum drying box to obtain the composite positive electrode materialTo the scale N@C/Mo@TiO 2 And S composite electrode plate.
Potassium metal is used as negative electrode, al 2 O 3 polyethylene/Al 2 O 3 Ceramic diaphragm, ethylene glycol dimethyl ether solution of 1mol/L potassium hexafluorophosphate as electrolyte, N@C/Mo@TiO prepared in example 1 2 The S composite electrode plate is used as an anode, and the 2025 type button potassium-sulfur battery is assembled.
N@C/Mo@TiO prepared in example 1 2 The charge-discharge curve and the cycle performance curve measured by the/S composite electrode assembled battery are shown in fig. 1 and 2, and as can be seen from fig. 1 and 2, when the current density is 0.1C, the specific capacity of the battery can reach 1394mAh/g, and when the current density is 0.2C, the specific capacity of the battery can reach 1083mAh/g, and when the current density is 0.5C, the specific capacity of the battery can reach 942mAh/g; after 30 cycles at 0.2C current density, the capacity retention was 62.78% of the original, after 50 cycles at 0.5C current density, the capacity retention was 85.21% of the original, after 50 cycles at 1C current density, the capacity retention was 90.93% of the original.
N@C/Mo@TiO prepared in example 1 2 As shown in FIG. 3, the XRD pattern of the composite material is shown in FIG. 3, and the XRD diffraction peak of the matrix material is compared with that of anatase TiO 2 The standard card was relative to, and a diffraction peak of molybdenum was observed, indicating that this material was molybdenum doped titanium dioxide.
Fig. 4 is a scanning electron micrograph (a corresponds to a large magnification and b corresponds to a small magnification) of the nitrogen-doped carbon material prepared in the step of example 1, from which the morphology of the scale shape can be well seen. The rough surface 1) can improve the storage of sulfur and potassium polysulfide, improve the utilization rate of sulfur and effectively inhibit the shuttle effect; 2) More active substances are loaded, so that the electrochemical activity of the active substances is effectively improved; 3) Providing a large specific surface area and a large number of active sites, improving the kinetics of the redox reaction and further increasing the conductivity of the material.
FIG. 5 is N@C/Mo@TiO prepared in example 1 2 Scanning electron microscope pictures of the/S composite material, (a corresponds to a large multiplying power and b corresponds to a small multiplying power), and active substances Mo doped TiO can be observed 2 Supported on an N-doped carbon layer and dispersedThe agglomeration phenomenon does not occur uniformly, the utilization rate of the material is greatly improved, and the conductivity is enhanced.
Example 2
(1) Scaly N@C/Mo@TiO 2 Preparation of/S composite electrode material
Weighing 4g of polyvinylpyrrolidone, carbonizing at 600 ℃ for 8 hours under the atmosphere of high-purity nitrogen, then annealing at 2 ℃/min, grinding, and then placing into an autoclave for sterilization treatment to obtain the scaly nitrogen-doped carbon material; with 3mL of tetrabutyl titanate (C) 16 H 36 O 4 Ti), 0.5mL of 36% concentrated hydrochloric acid (HCl), 1.5mL of absolute ethanol (C) 2 H 6 O) to prepare C 16 H 36 O 4 Ti/HCl/C 2 H 6 The mixed solution of O is stirred continuously for 12 hours to obtain stable and uniform TiO 2 A precursor solution; 10mL of deionized water and 1.25mL of concentrated hydrochloric acid were uniformly mixed, followed by addition of ammonium molybdate tetrahydrate ((NH) having a mass of 0.16g 4 ) 6 Mo 7 O 24 ·4H 2 O), continuously stirring for 1h to obtain a clear ammonium molybdate solution; weighing 0.4g of scale-shaped nitrogen-doped carbon material, adding the prepared ammonium molybdate solution into TiO 2 Continuously stirring the precursor solution for 12 hours, carrying out hydrothermal reaction for 16 hours at 150 ℃ in a hydrothermal kettle after uniformly mixing, putting the synthesized material into a drying box, drying at 70 ℃ for 12 hours, and then grinding to obtain N@C/Mo@TiO 2 A composite material;
to be synthesized N@C/Mo@TiO 2 Adding sulfur powder into the composite material to make the mass ratio of the sulfur powder to the composite material be 1:3, heating and preserving heat for 24 hours at 160 ℃ to obtain N@C/Mo@TiO 2 and/S composite positive electrode material.
(2) Application of scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode composite positive electrode material as positive electrode plate of potassium-sulfur battery
N@C/Mo@TiO 2 The preparation method comprises the steps of (1) regulating the viscosity degree of a composite positive electrode material, conductive carbon black (Super-P) and polyvinylidene fluoride (Polyvinylidene Fluoride) to be uniform paste according to the mass ratio of 7:2:1 by using a proper amount of N-methyl pyrrolidone (NMP), and rapidly and uniformly coating the active material slurry on the surface of an aluminum foil with the thickness of 15 mu m by using a clean bladeCoating thickness of 0.05mm, and vacuum drying at 50deg.C for 12 hr to obtain scale N@C/Mo@TiO 2 And S composite electrode plate.
Potassium metal is used as negative electrode, al 2 O 3 polyethylene/Al 2 O 3 Ceramic diaphragm, ethylene glycol dimethyl ether solution of 1mol/L potassium hexafluorophosphate as electrolyte, N@C/Mo@TiO prepared in example 1 2 The S composite electrode plate is used as an anode, and the 2025 type button potassium-sulfur battery is assembled.
Example 3
(1) Scaly N@C/Mo@TiO 2 Preparation of/S composite electrode material
Weighing 6g of polyvinylpyrrolidone, carbonizing at 1000 ℃ for 2 hours under the atmosphere of high-purity nitrogen at high temperature, then annealing at 3 ℃/min, grinding, and then placing into an autoclave for sterilization treatment to obtain the scaly nitrogen-doped carbon material; with 3mL of tetrabutyl titanate (C) 16 H 36 O 4 Ti), 1.5mL of 36% concentrated hydrochloric acid (HCl), 6mL of absolute ethanol (C) 2 H 6 O) to prepare C 16 H 36 O 4 Ti/HCl/C 2 H 6 The stable and uniform TiO can be obtained by continuously stirring the O mixed solution for 24 hours 2 A precursor solution; 10mL of deionized water and 2mL of concentrated hydrochloric acid were uniformly mixed, followed by the addition of ammonium molybdate tetrahydrate ((NH) having a mass of 0.8g 4 ) 6 Mo 7 O 24 ·4H 2 O), continuously stirring for 4 hours to obtain a clear ammonium molybdate solution; weighing 0.8g of scale-shaped nitrogen-doped carbon material, adding the prepared ammonium molybdate solution into TiO 2 Continuously stirring the precursor solution for 20 hours, uniformly mixing, performing hydrothermal reaction for 32 hours at 200 ℃ in a hydrothermal kettle, putting the synthesized material into a drying box, drying at 90 ℃ for 20 hours, and grinding to obtain N@C/Mo@TiO 2 A composite material;
to be synthesized N@C/Mo@TiO 2 Adding sulfur powder into the composite material to make the mass ratio of the sulfur powder to the composite material be 1:3, heating and preserving heat for 30 hours at 180 ℃ to obtain N@C/Mo@TiO 2 and/S composite positive electrode material.
(2) Application of scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode composite positive electrode material as positive electrode plate of potassium-sulfur battery
N@C/Mo@TiO 2 The preparation method comprises the steps of (1) regulating the viscosity degree of a composite positive electrode material, conductive carbon black (Super-P) and polyvinylidene fluoride (Polyvinylidene Fluoride) to be uniform paste according to the mass ratio of 7:2:1 by using a proper amount of N-methyl pyrrolidone (NMP), rapidly and uniformly coating one side of the obtained active substance slurry on the surface of an aluminum foil with the thickness of 15 mu m by using a clean blade, coating the surface with the thickness of 0.05mm, and then carrying out vacuum drying for 12 hours at 50 ℃ by using a vacuum drying oven to obtain scaly N@C/Mo@TiO 2 And S composite electrode plate.
Potassium metal is used as negative electrode, al 2 O 3 polyethylene/Al 2 O 3 Ceramic diaphragm, ethylene glycol dimethyl ether solution of 1mol/L potassium hexafluorophosphate as electrolyte, N@C/Mo@TiO prepared in example 1 2 The S composite electrode plate is used as an anode, and the 2025 type button potassium-sulfur battery is assembled.
The invention prepares the unique scaly carbon by a simple and efficient thermal decomposition method, and prepares Mo@TiO by a simple and easily available sol-gel method and a one-step hydrothermal method 2， By regulating N@C and Mo@TiO 2 Is used for constructing unique scaly N@C/Mo@TiO 2 Double adsorption of polysulfide by composite material, under the influence of synergistic effect, combination of scaly nitrogen doped carbon and Mo@TiO 2 High-efficiency physical and chemical adsorption of polysulfide, inhibition of shuttle effect, simple and novel process, low cost and rapid preparation. Further improving the electrochemical performance of the battery and providing a promising strategy for the development of potassium-sulfur batteries and other energy storage devices.
Although the present invention has been described with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements and changes may be made without departing from the spirit and principles of the present invention.

Claims (9)

1. The preparation method of the scaly nitrogen-doped carbon composite molybdenum-doped titanium dioxide-sulfur electrode for the potassium-sulfur battery is characterized by comprising the following steps of:
s1, weighing a proper amount of polyvinylpyrrolidone, carbonizing for a period of time at a high temperature in a high-purity nitrogen atmosphere, then performing annealing treatment at a speed of 1-3 ℃/min, grinding, and then performing sterilization treatment to obtain a scaly nitrogen-doped carbon material;
s2, dropwise adding absolute ethyl alcohol into the mixed solution of tetrabutyl titanate and concentrated hydrochloric acid, and continuously stirring for a period of time to obtain TiO 2 A precursor solution;
s3, evenly mixing deionized water and concentrated hydrochloric acid in a volume ratio of 10:1-5:1, and then adding the mixture according to TiO 2 TiO in precursor solution 2 The mass ratio of the ammonium molybdate tetrahydrate to the ammonium molybdate tetrahydrate is 10:1-1:1, and stirring is carried out for 1-4 hours to obtain an ammonium molybdate solution;
s4, adding the scaly nitrogen-doped carbon material obtained in the step S1 and the ammonium molybdate solution obtained in the step S3 into the TiO obtained in the step S2 2 Continuously stirring the precursor solution for 8 to 20 hours, uniformly mixing, and carrying out hydrothermal reaction in a hydrothermal kettle at the temperature of between 100 and 200 ℃ for 8 to 32 hours;
s5, placing the material obtained in the step S4 into a drying oven for drying, and grinding to obtain N@C/Mo@TiO 2 A composite powder material;
s6, N@C/Mo@TiO synthesized in step S5 2 Adding sulfur powder into the composite powder material, heating and preserving heat for 15-30 hours at 120-180 ℃ to obtain N@C/Mo@TiO 2 S composite positive electrode material; wherein Mo-doped TiO 2 Is supported on the N-doped carbon layer, and is uniformly dispersed without agglomeration;
the high-temperature carbonization temperature in the step S1 is 600-1000 ℃; the high-temperature carbonization time is 8-10 h.
2. The method for producing a scaly nitrogen-doped carbon composite molybdenum-doped titania-sulfur electrode for a potassium-sulfur cell according to claim 1, characterized in that: in the step S2, the volume ratio of tetrabutyl titanate to concentrated hydrochloric acid is 12:1-2:1; the volume ratio of tetrabutyl titanate to absolute ethyl alcohol is 1:2-1:4.
3. The method for producing a scaly nitrogen-doped carbon composite molybdenum-doped titania-sulfur electrode for a potassium-sulfur cell according to claim 1, characterized in that: the dropping speed of the absolute ethyl alcohol in the step S2 is 3 mL/min-6 mL/min; the continuous stirring period is 8-24 hours.
4. The method for producing a scaly nitrogen-doped carbon composite molybdenum-doped titania-sulfur electrode for a potassium-sulfur cell according to claim 1, characterized in that: in the step S4, tiO 2 TiO in precursor solution 2 The mass ratio of the ammonium molybdate to the ammonium molybdate added to the ammonium molybdate solution is 5:1; tiO (titanium dioxide) 2 TiO in precursor solution 2 The mass ratio of the added scale-shaped nitrogen-doped carbon material is 8:1-1:1.
5. The method for producing a scaly nitrogen-doped carbon composite molybdenum-doped titania-sulfur electrode for a potassium-sulfur cell according to claim 1, characterized in that: in the step S5, the drying temperature is 60-90 ℃ and the drying time is 8-20 h.
6. The method for producing a scaly nitrogen-doped carbon composite molybdenum-doped titania-sulfur electrode for a potassium-sulfur cell according to claim 1, characterized in that: in the step S6, N@C/Mo@TiO 2 The mass ratio of the composite powder material to the sulfur powder is 1:3.
7. The method for producing a scaly nitrogen-doped carbon composite molybdenum-doped titania-sulfur electrode for a potassium-sulfur cell according to claim 1, characterized in that: the concentration of the concentrated hydrochloric acid is 36%.
8. A scaly nitrogen-doped carbon-doped composite molybdenum-doped titanium dioxide-sulfur electrode composite positive electrode material for a potassium-sulfur battery prepared by the preparation method of the scaly nitrogen-doped carbon-doped composite molybdenum-doped titanium dioxide-sulfur electrode according to any one of claims 1 to 7Is characterized in that: scaly N@C/Mo@TiO 2 Mixing the S composite positive electrode material, the conductive carbon black and the polyvinylidene fluoride according to the mass ratio of 7:2:1, adding N-methyl pyrrolidone, stirring into uniform paste, coating the paste on the surface of an aluminum foil with the thickness of 15 mu m, coating the thickness of 0.05mm, and then vacuum drying by using a vacuum drying oven to obtain scaly N@C/Mo@TiO 2 And S composite electrode plate.
9. The use according to claim 8, characterized in that: the vacuum drying temperature is 50-90 ℃; the drying time is 12-24 hours.
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