GB2583828A

GB2583828A - Sulfur/Silica/Polyaniline core-shell structure nanocomposite for cathode of lithium-sulfur battery and method for preparing same

Info

Publication number: GB2583828A
Application number: GB2002888.2A
Authority: GB
Inventors: Zhou Guowei; Gong Qinghua; Gu Shaonan; Sun Xuefeng; Hu Tingting
Original assignee: Qilu University of Technology
Current assignee: Qilu University of Technology
Priority date: 2019-04-03
Filing date: 2020-02-28
Publication date: 2020-11-11
Also published as: GB202002888D0; CN109802128B; CN109802128A

Abstract

A sulfur/silica/polyaniline core-shell structure nanocomposite for a cathode of a lithium-sulfur battery and a method for preparing the same are disclosed. The composite comprises sulfur-loaded nano silica as the core, and polyaniline as the shell. The nano silica has a spherical structure, a plurality of radial mesoporous channels are arranged in the spherical structure, and sulfur is loaded in the radial mesoporous channels of the nano silica. The polyaniline coating serves to improve electrical conductivity of an active electrode material. The nano silica spheres are preferably made using ethanol, water and cyclohexane as cosolvents, CTAB as a surfactant, PVP as a wrapping agent, ammonia water as a catalyst and TEOS as a silicon source. The components may be stirred at room temperature, transferred to a reaction kettle, subjected to a solvothermal reaction and finally subjecting to high temperature calcination to form spherical silica nanomaterial with radial mesoporous channels. The core-shell nanocomposite is then prepared by melting and diffusing sulfur into the mesoporous channels of the nano silica spheres before dispersing the sulfur-loaded silica into water, adding aniline to the suspension and causing polymerisation of the aniline to form the polyaniline shell coating.

Description

SULFUR/SILICA/POLYANILINE CORE-SHELL STRUCTURE NANOCOMPOSITE FOR CATHODE OF LITHIUM-SULFUR BATTERY AND METHOD FOR PREPARING SAME

TECHNICAL FIELD

The present disclosure relates to the technical field of lithium-sulfur batteries, and in particular, to a sulfur/silica/polyaniline core-shell structure nanocomposite for a cathode of a lithium-sulfur battery and a method for preparing the same.

BACKGROUND

The statements herein merely provide background information related to the present disclosure and do not necessarily constitute the prior art.

With the rapid development of industrial society, fossil fuels such as oil and coal are consumed in large quantities, and environmental pollution is becoming increasingly serious. Human beings urgently need to explore sustainable new energy. Clean energy such as solar energy, wind energy, tidal energy and geothermal energy needs to be converted by an electrochemical energy storage system before being applied. A lithium-ion battery is one of the most promising electric energy storage systems due to its high energy density, high output voltage, long service life, low self-discharge rate and environmental friendliness. However, currently commercialized lithium-ion batteries cannot meet the high energy requirements of fixed grid energy storage. The limited energy density of batteries also hinders the application of lithium-ion batteries in various emerging mobile means of transport. This has led the world to explore new battery technologies beyond traditional lithium-ion batteries.

A lithium-sulfur battery is a promising energy storage system, which has a higher energy density than the existing lithium-ion battery. The main difference between the two types of batteries lies in their energy storage mechanisms. The lithium-ion battery is based on lithium ions inserted into a layered electrode material. Since the lithium ions can only be inserted into certain specific points, the theoretical energy density of the lithium-ion battery is usually limited to about 420Wh kg'. The lithium-sulfur battery is based on the electroplating and stripping of metals on a lithium anode side and a conversion reaction of sulfur on a cathode side. The non-topological property of these reactions endows the lithium anode and the lithium cathode with high theoretical specific capacities of 3860 mA h g' and 1675 mA h g', respectively. The average battery voltage of 2.15 V gives the lithium-sulfur battery a high theoretical energy density of 2600 Wh kg'. In addition, sulfur is abundant and cheap on the surface of the earth, which makes the lithium-sulfur battery an attractive and low-cost energy storage technology.

The theoretical density of silica is 2.65 g cm-3, which is one of the lightest solid oxides. The silica can provide a mesoporous body and mechanical support to reduce the negative impact of large volume change (up to 80%) between S and Li2S, otherwise a conductive network may be broken. In addition, different morphologies of silica have been studied as cathode materials of lithium-sulfur batteries, such as nanosheets, nanotubes and nanoboxes, and composites of silica and other materials have also been actively studied.

The Chinese patent document with application publication number CN 104183834 A (application number 201410399926.2) discloses a method for preparing a sulfur/silica core-shell nanostructure for a cathode of a lithium-sulfur battery. The patent uses sulfur particles as a template and uses a hydrolytic polycondensation process of tetraethyl orthosilicate (TEOS) to coat nanoporous silica to obtain a sulfur/silica core-shell nanostructure. However, it can be clearly seen from its SEM image that the material prepared by this test solution has poor dispersibility, serious adhesion and uneven coating of a silica shell. The Chinese patent document with application publication number CN 105742587B (application number 201610105962.2) discloses a method for preparing a sulfur/silica gel three-dimensional composite for an anode of a lithium-sulfur battery. In this patent, a sol-gel method is utilized to directly add sublimed sulfur to TEOS and an ethanol solution to generate a sulfur/silica gel three-dimensional composite in situ. Then an acid and a hexamethylenetetramine aqueous solution are added dropwise to obtain a gel, and the gel stands and then is subjected to freeze drying to obtain solid powder. The solid powder is dispersed with ethanol water and centrifuged and washed to be neutral, and dried to obtain the sulfur/silica gel three-dimensional composite. The preparation process is complicated and corrosive toxic chemicals are used, which does not conform to the concept of green chemistry. At the same time, it is found by the inventor of the present disclosure that the first discharge specific capacity of the material is only 900 mA h g-1, and the electrochemical performance still has room for improvement.

SUMMARY

In order to solve the defects of the prior art, an objective of the present disclosure is to provide a sulfur/silica/polyaniline core-shell structure nanocomposite for a cathode of a lithium-sulfur battery and a method for preparing the same. The sulfur/silica/conductive polyaniline ternary composite with a special structure is designed and prepared by utilizing the synergistic effect of the chemical adsorption of silica on polysulfide ions and the improvement of the conductive performance of an active substance by conductive polyaniline, and is used for improving the electrochemical performance of the lithium-sulfur battery. The preparation method of the present disclosure is simple, safe in preparation process, low in energy consumption and high in operability.

In order to achieve the foregoing objective, the technical solution of the present disclosure is as follows.

In a first aspect, a sulfur/silica/polyaniline core-shell structure nanocomposite is provided, where sulfur-loaded nano silica is used as a core of a core-shell structure, and polyaniline is used as a shell of the core-shell structure. The nano silica has a spherical structure. A plurality of radial mesoporous channels are arranged in the spherical structure, and sulfur is loaded in the radial mesoporous channels of the nano silica.

According to the present disclosure, the spherical nano silica has the radial mesoporous channels, so that the specific surface area of the material can be increased, and more sulfur can be loaded. Rapid conversion of lithium polysulfide is promoted, and thus the electrochemical performance of the lithium-sulfur battery prepared from the composite is improved.

According to the present disclosure, the polyaniline is used as the shell. Firstly, the conductivity of the polyaniline is beneficial to electron conduction; secondly, the polyaniline has excellent elasticity and flexibility, which can accommodate the volume change of some sulfur during charging and discharging; and thirdly, the polyaniline has a strong affinity for the lithium polysulfide. Therefore, the electrochemical performance of the lithium-sulfur battery prepared from the composite is further improved.

In another aspect, a method for preparing the foregoing composite is provided. Sulfur is heated to melt, the melted sulfur is diffused into radial mesoporous channels of nano silica to obtain sulfur-loaded nano silica (sulfur/silica). The sulfur-loaded nano silica is dispersed into water to obtain a suspension. Aniline is added to the suspension for polymerization of the aniline, and a sulfur/silica/polyaniline core-shell structure nanocomposite is obtained after the reaction.

The melting point of the sulfur is 112.8°C. The sulfur is loaded on the nano silica by using a melt diffusion method, and the temperature is lower, which can reduce energy consumption.

In a third aspect, use of the foregoing composite in the preparation of electronic materials, magnetic materials, catalytic materials, sensing materials, photoelectric materials or energy storage materials is provided.

In a fourth aspect, a cathode material of a lithium-sulfur battery includes the foregoing composite.

In a fifth aspect, a lithium-sulfur battery uses the foregoing cathode material as a cathode, and uses a lithium sheet as an anode. It is verified through tests that the discharge specific capacity of the lithium-sulfur battery can reach 1088.4 mA h g-1 when the current density is 0.2 C. Beneficial effects of the present disclosure are as follows: 1. In the present disclosure, nano silica having a spherical structure with radial mesoporous channels is used as a sulfur main body, so that the specific surface area can be increased, and the contact area between the nano silica and sulfur can be increased. The rapid conversion of lithium polysulfide can be promoted, so that the lithium polysulfide has a good application prospect in

the electrochemical field.

2. The spherical sulfur/silica/polyaniline core-shell structure nanocomposite with the radial mesoporous channels provided by the present disclosure has good dispersibility and no obvious aggregation. The problem that the spherical polyaniline composite agglomerates easily is solved. The interfacial resistance in the charge transfer process is reduced, and the electrochemical performance can be improved.

3. The spherical sulfur/silica/polyaniline core-shell structure nanocomposite with the radial mesoporous channels provided by the present disclosure has the obvious radial mesoporous channels, and the electrochemical performance can be improved.

4. In the present disclosure, sulfur/silica is prepared by using a melt diffusion method, and the temperature is lower, and the energy consumption can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompany drawings of the specification constituting a part of the present disclosure provide further understanding of the present disclosure. The schematic embodiments of the present disclosure and description thereof are intended to be illustrative of the present disclosure and do not constitute an undue limitation of the present disclosure.

FIG. I is a transmission electron microscope (TEM) image of spherical silica with radial mesoporous channels prepared in Embodiment 1 of the present disclosure; FIG. 2 is a TEM image of a spherical silica/sulfur composite with radial mesoporous channels prepared in Embodiment I of the present disclosure; FIG. 3 is a TEM image of a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels prepared in Embodiment 1 of the present disclosure; FIG. 4 is an EDS energy spectrum diagram of the spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels prepared in Embodiment 1 of the present disclosure; FIG. 5 is a cycle performance chart of a lithium-sulfur battery prepared in Embodiment 8 of the present disclosure; and FIG. 6 is a charge-discharge curve graph of lithium-sulfur batteries prepared in Embodiments 8 and 9 of the present disclosure, where a shows Embodiment 9 and b shows Embodiment 8. DETAILED DESCRIPTION It should be noted that the following detailed description is exemplary and aims to further describe the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the present disclosure belongs.

It should be noted that the terms used herein are merely used for describing the specific embodiments, but are not intended to limit exemplary embodiments of the present disclosure. As used herein, the singular form is also intended to include the plural form unless otherwise indicated obviously from the context. Furthermore, it should be further understood that the terms "include" and/or "comprise" used in this specification specify the presence of stated features, steps, operations, elements, components and/or a combination thereof.

According to the definition of International Union of Pure and Applied Chemistry (IUPAC), pores with pore diameters less than 2 nm are called micropores. Pores with pore diameters greater than 50 nm are called macropores. Pores with pore diameters of 2-50 nm are called mesopores. The mesopores described in the present disclosure refer to pores with a pore diameter of 2-50 nm.

In view of the defects of poor dispersibility, serious adhesion, complex preparation method, low electrochemical performance and the like of a sulfur/silica composite, in order to solve the foregoing technical problems, the present disclosure provides a sulfur/silica/polyaniline core-shell structure nanocomposite for a cathode of a lithium-sulfur battery and a method for preparing the same.

A typical embodiment of the present disclosure provides a sulfur/silica/polyaniline core-shell structure nanocomposite. Sulfur-loaded nano silica is used as a core of a core-shell structure, and polyaniline is used as a shell of the core-shell structure. The nano silica has a spherical structure. A plurality of radial mesoporous channels are arranged in the spherical structure, and sulfur is loaded in the radial mesoporous channels of the nano silica.

In one or more embodiments, the core-shell structure has a particle size of 440-580 nm.

In one or more embodiments, the sulfur-loaded silica has a diameter of 400-500 nm.

In one or more embodiments, the polyaniline shell has a thickness of 20-40 nm.

Another embodiment of the present disclosure provides a method for preparing the foregoing composite. Sulfur is heated to melt, the melted sulfur is diffused into radial mesoporous channels of nano silica to obtain sulfur-loaded nano silica (sulfur/silica). The sulfur-loaded nano silica is dispersed into water to obtain a suspension. Aniline is added to the suspension for polymerization of the aniline, and a sulfur/silica/polyaniline core-shell structure nanocomposite is obtained after the reaction.

In one or more embodiments, after the sulfur is evenly mixed with the nano silica, the mixture is heated to no less than 112.8°C under inert atmosphere for calcination to obtain the sulfur-loaded nano silica. The inert atmosphere is an atmosphere capable of preventing oxidation of oxygen, such as a nitrogen atmosphere and an argon atmosphere.

In order to enable the sulfur to better enter the radial mesoporous channels of the nano silica, in the series of embodiments, the calcination temperature is 150-160°C, and the calcination time is 6-24 h. When the calcination temperature is 155°C and the calcination time is 12 h, the electrochemical performance of the lithium-sulfur battery prepared from the obtained composite is better.

In one or more embodiments, the ratio of the mass of the nano silica to the mass of the sulfur is 1:(3-5). When the ratio of the mass of the nano silica to the mass of the sulfur is 1:4, the electrochemical performance of the lithium-sulfur battery prepared from the obtained composite is better.

In order to more evenly disperse the sulfur-loaded nano silica into water, in one or more embodiments, the sulfur-loaded nano silica and PVP are added into water and evenly mixed to obtain a suspension.

In the series of embodiments, the ratio of the mass of the sulfur-loaded nano silica to the mass of the PVP is (10-30):(50-150). When the ratio of the mass of the sulfur-loaded nano silica to the mass of the PVP is 20:100, the dispersion effect on the sulfur-loaded nano silica is better.

The addition of the PVP is conducive to the polymerization of aniline on the surface of sulfur/silica, and at the same time makes the composite dispersed more evenly.

In order to obtain nano silica with radial mesoporous channels, in one or more embodiments, a method for preparing nano silica is provided. The method takes ethanol, water and cyclohexane as cosolvents, cetyl trimethyl ammonium bromide (CTAB) as a surfactant, the PVP as a wrapping agent, ammonia water as a catalyst and TEOS as a silicon source. The components are evenly mixed under conditions of stirring at room temperature, and then the mixed solution is transferred to a reaction kettle, silica containing the CTAB and the PVP is prepared through solvothermal reaction. Finally a spherical silica nanomaterial with radial mesoporous channels can be obtained through high-temperature calcination.

The spherical silica with the radial mesoporous channels prepared in the embodiment is synthesized only by one step, and does not need etching by a template. A preparation method is simple and the controllability is high. In this embodiment, spherical silica with radial mesoporous channels is prepared by using a solvothermal method, and the preparation process of the method is safe and environmentally friendly.

The high temperature mentioned in the present disclosure refers to a temperature not less than 500°C.

The solvothermal reaction described in the present disclosure refers to a synthetic method in which an original mixture is reacted in a closed system such as an autoclave with an organism or a non-aqueous solvent as a solvent at a certain temperature and autogenous pressure of the solution.

The molecular weights of the TEOS, the cyclohexane, the CTAB and the PVP are 208.33 g mof I, 84.16 g mol-I and 364.45 g mot respectively.

The PVP is a non-ionic polymer compound with an average molecular weight generally being 8000-700000. The effect of using PVP with a molecular weight of 10000.00 g/mol in the present disclosure is better.

In the series of embodiments, the ratio of the volume of the ethanol to the volume of the water to the volume of the cyclohexane is (20-30):(10-20):(3-5). After optimization, when the ratio of the volume of the ethanol to the volume of the water to the volume of the cyclohexane is 25:(15-20):4, the morphology of the obtained nano silica is better.

In the series of embodiments, the ratio of the mass of the CTAB to the mass of the PVP is (0.06-0.10):(0.02-0.08). When the mass ratio is 0.08:0.04, the effect is better.

In the series of embodiments, the ratio of the volume of the TEOS to the volume of the ammonia water is (0.4-0.6):(0-1). The ammonia water is not 0 and the mass concentration is 23%-25%. When the ratio of the volume of the TEOS to the volume of the ammonia water is 0.5:0.5, the effect is better.

In this series of embodiments, the solvothermal reaction temperature is 80-120°C. After optimization experiments, when the temperature is 100°C, the reaction efficiency is higher and the morphology of the nano silica is better.

In this series of embodiments, the high-temperature calcination temperature is 500-600°C. When the high-temperature calcination temperature is 550°C, the calcination time is short, which can ensure that the nano silica has a better morphology and prevent the energy consumption from increasing due to too high temperature.

In order to better obtain the core-shell structure, in one or more embodiments, steps for carrying out the polymerization include: adding a hydrochloric acid solution of the aniline into the suspension, mixing evenly, and then adding an initiator for reaction.

In order to reduce the reaction time, in this series of embodiments, after the initiator is added into water for dissolution, the initiator solution is added into the mixed solution of the hydrochloric acid solution of the aniline and the suspension. The time of the initiator dissolution process is reduced.

In this series of embodiments, the initiator is ammonium persulfate.

In this series of embodiments, the input ratio of the aniline to the ammonium persulfate is (10-30):(26-78), !IL:mg. The ratio with the better effect is 20:52, pL:mg.

In this series of embodiments, the hydrochloric acid solution has a concentration of 0.5-2 mol L-1. In order to facilitate the experiment, the concentration of the hydrochloric acid used in the embodiments provided by the present disclosure is 1 mol L-1.

In order to obtain a pure sulfur/silica/polyaniline core-shell structure nanocomposite, in one or more embodiments, precipitate after polymerization is separated, washed and dried.

A third embodiment of the present disclosure provides use of the foregoing composite in the preparation of electronic materials, magnetic materials, catalytic materials, sensing materials, photoelectric materials or energy storage materials.

This embodiment mainly provides use of the foregoing composite in a lithium-sulfur battery. A fourth embodiment of the present disclosure provides a cathode material of a lithium-sulfur battery, which includes the foregoing composite.

A fifth embodiment of the present disclosure provides a lithium-sulfur battery that uses the foregoing cathode material as a cathode, and uses a lithium sheet as an anode. It is verified through tests that the discharge specific capacity of the lithium-sulfur battery can reach 1088.4 mA h g1 when the current density is 0.2 C. In one or more embodiments, a polypropylene film is used as a separator.

In one or more embodiments, 1,3 dioxolane (DOL)/dimethoxyethane (DME) lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is used as an electrolyte.

In order to enable those skilled in the art to more clearly understand the technical solution of the present disclosure, the technical solution of the present disclosure will be described in detail below with reference to specific embodiments and comparative examples.

Embodiment 1 (1) Preparation of spherical silica with radial mesoporous channels: mL of ethanol, 15 mL of water and 4 mL of cyclohexane were first used as cosolvents, and 0.08 g of CTAB, 0.04 g of PVP, 0.5 g of TEOS and 0 5 mL of ammonia water (with a mass concentration of 24%) were sequentially added. The mixture was stirred for 4 h at room temperature for uniform mixing. Then the mixed solution was transferred to a 100 mL polytetrafluoroethylene lined autoclave. After solvothermal reaction at 100°C for 12 h, the autoclave was naturally cooled to room temperature, and silica containing the CTAB and the PVP was centrifuged, washed and dried. Finally, the product was placed in a box-type calcination furnace and calcined at 550°C for 6 h to obtain spherical silica nanomaterial powder with radial mesoporous channels.

A TEM image of the product is shown in FIG. 1. The product silica has a spherical shape with an average particle size of 450 nm. Radioactive mesopores can be seen, but the pore sizes of the radioactive mesopores are different.

(2) Preparation of sulfur/silica: 1) Silica nanospheres and elemental sulfur were ground at a mass ratio of 1:4 for full mixing.

2) The physically mixed silica and sulfur were calcined at 155°C for 12 h in inert gas atmosphere to obtain spherical sulfur/silica.

A TEM image of the product is shown in FIG. 2. The product sulfur/silica has a spherical shape with an average particle size of 450 nm, and has significantly smaller mesopores compared with silica spheres.

(3) Preparation of a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels: 1) 20 mg of sulfur/silica and 100 mg of PVP were dispersed in water.

2) 20 [IL of aniline was dispersed in 20 ml of FICI solution with a concentration of 1 mol 3) The solution prepared in step 2) was evenly mixed with the suspension prepared in step 1).

4) 52 mg of APS was dissolved in water.

5) The solution prepared in step 4) was evenly mixed with the suspension obtained in step 3) for reaction.

6) The precipitate prepared in step 5) was separated, washed, dried and ground to obtain a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels.

It is observed by a TEM that, as shown in FIG. 3, the spherical sulfur/silica/polyaniline core-shell structure nanocomposite with the radial mesoporous channels prepared in the method has a diameter in the range of 440-580 nm. A silica core diameter is 400-500 nm, a polyaniline shell thickness is 20-40 nm, and there is no gap between the core and the shell.

Through X-ray spectrum (EDS), as shown in FIG. 4, the presence of carbon, nitrogen, oxygen, silicon and sulfur elements can be found from the elemental energy spectrum, further proving the successful preparation of the sulfur/silica/polyaniline composite.

Embodiment 2 (1) Preparation of spherical silica with radial mesoporous channels: mL of ethanol, 15 mL of water and 4 mL of cyclohexane were first used as cosolvents, and 0.08 g of CTAB, 0.02 g of PVP, 0.5 g of TEOS and 0 5 m.L. of ammonia water (with a mass concentration of 24%) were sequentially added. The mixture was stirred for 4 h at room temperature for uniform mixing. Then the mixed solution was transferred to a 100 mL polytetrafluoroethylene lined autoclave. After solvothermal reaction at 100°C for 12 h, the autoclave was naturally cooled to room temperature, and silica containing the CTAB and the PVP was centrifuged, washed and dried. Finally, the product was placed in a box-type calcination furnace and calcined at 550°C for 6 h to obtain spherical silica nanomaterial powder with radial mesoporous channels.

(2) The preparation of sulfur/silica was the same as step (2) in Embodiment 1.

(3) The preparation of a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels was the same as step (3) in Embodiment 1. Embodiment 3 (1) Preparation of spherical silica with radial mesoporous channels: mL of ethanol, 15 mL of water and 4 mL of cyclohexane were first used as cosolvents, and 0.08 g of CTAB, 0.08 g of PVP, 0.5 g of TEOS and 0.5 mL of ammonia water (with a mass concentration of 24%) were sequentially added. The mixture was stirred for 4 h at room temperature for uniform mixing. Then the mixed solution was transferred to a 100 mI, polytetrafluoroethylene lined autoclave. After solvothermal reaction at 100'C for 12 h, the autoclave was naturally cooled to room temperature, and silica containing the CTAB and the PVP was centrifuged, washed and dried. Finally, the product was placed in a box-type calcination furnace and calcined at 550°C for 6 h to obtain spherical silica nanomaterial powder with radial mesoporous channels.

(2) The preparation of sulfur/silica was the same as step (2) in Embodiment 1.

(3) The preparation of a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels was the same as step (3) in Embodiment 1. Embodiment 4 (1) The preparation of spherical silica with radial mesoporous channels was the same as step (1) in Embodiment 1.

(2) Preparation of sulfur/silica: 1) Silica nanospheres and elemental sulfur were ground at a mass ratio of 1:3 for full mixing.

(3) The preparation of a spherical sulfuesilica/polyandine core-shell structure nanocomposite with radial mesoporous channels was the same as step (3) in Embodiment 1.

Embodiment 5 (1) The preparation of spherical silica with radial mesoporous channels was the same as step (1) in Embodiment 1.

(2) Preparation of sulfur/silica: 1) Silica nanospheres and elemental sulfur were ground at a mass ratio of 1:5 for full mixing.

(3) The preparation of a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels was the same as step (3) in Embodiment 1. Embodiment 6 (1) The preparation of spherical silica with radial mesoporous channels was the same as step (1) in Embodiment 1.

(2) The preparation of sulfur/silica was the same as step (2) in Embodiment 1.

2) 10 µL of aniline was dispersed in 20 ml of HCI solution with a concentration of 1 mol 3) The solution prepared in step 2) was evenly mixed with the suspension prepared in step 1).

4) 26 mg of APS was dissolved in water.

6) The precipitate prepared in step 5) was separated, washed, dried and ground to obtain a radial spherical sulfur/silica/polyaniline core-shell structure nanocomposite. Embodiment 7 (1) The preparation of spherical silica with radial mesoporous channels was the same as step (1) in Embodiment 1.

(2) The preparation of sulfur/silica was the same as step (2) in Embodiment 1 (3) Preparation of a spherical sulfur/silica/polyaniline core-shell structure nanocomposite with radial mesoporous channels: 1) 20 mg of sulfur/silica and 100 mg of PVP were dispersed in water.

2) 40 [d_. of aniline was dispersed in 20 ml of HCI solution with a concentration of 1 mol 3) The solution prepared in step 2) was evenly mixed with the suspension prepared in step 1).

4) 104 mg of APS was dissolved in water.

6) The precipitate prepared in step 5) was separated, washed, dried and ground to obtain a radial spherical sulfur/silica/polyanline core-shell structure nanocomposite.

Embodiment 8 A lithium-sulfur battery was provided. With respect to an electrode material of the lithium-sulfur battery, the spherical sulfur/silica/polyaniline core-shell structure nanocomposite with the radial mesoporous channels in Embodiment 1 was used as a cathode of the lithium-sulfur battery, a lithium sheet was used as an anode. A polypropylene film was used as a separator, and 1,3 DOL/DME LiTFSI was used as electrolyte. A CR2032-type button battery was assembled in a glovebox fill with argon, and then LAND-CT2001A was used to perform charging and discharging performance tests. As can be seen from FIG. 5, when the current density was 0.2 C, the initial discharge specific capacity was 1088.4 mA h g-1, and after 100 cycles of charging and discharging, the capacity retention rate was 73%.

Embodiment 9 Preparation of a sulfur/polyaniline composite: 1) 20 mg of sulfur and 100 mg of PVP were dispersed in water.

2) 40 IA_ of aniline was dispersed in 20 ml of NCI solution with a concentration of 1 mol 3) The solution prepared in step 2) was evenly mixed with the suspension prepared in step 1).

4) 104 mg of APS was dissolved in water.

6) The precipitate prepared in step 5) was separated, washed, dried and ground to obtain a sulfur/polyaniline nanocomposite.

As a comparative example, the sulfur/polyaniline composite was used as a cathode of a lithium-sulfur battery, and the electrochemical performance was tested. As can be seen from FIG. 6a, when the current density was 0.2 C, the discharge specific capacity was 795.2 mA h which was lower than the discharge specific capacity of the spherical sulfur/silica/polyaniline core-shell structure nanocomposite with the radial mesoporous channels (1088.4 mA h g-1 (FIG. 6b)).

The foregoing is merely illustrative of the preferred embodiments of the present disclosure and is not intended to limit the present disclosure, and various changes and modifications can be made to the present disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and scope of the present disclosure should fall within the protection scope of the present disclosure.

Claims

What is claimed is: 1. A sulfur/silica/polyaniline core-shell structure nanocomposite, wherein sulfur-loaded nano silica is used as a core of a core-shell structure, and polyaniline is used as a shell of the core-shell structure; the nano silica has a spherical structure, a plurality of radial mesoporous channels are arranged in the spherical structure, and sulfur is loaded in the radial mesoporous channels of the nano silica.
2. The composite according to claim 1, wherein the core-shell structure has a particle size of 440-580 nm; or the sulfur-loaded silica has a diameter of 400-500 nm; or the polyaniline shell has a thickness of 20-40 nm.
3. A method for preparing the composite according to claim 1 or 2, wherein sulfur is heated to melt, the melted sulfur is diffused into radial mesoporous channels of nano silica to obtain sulfur-loaded nano silica, the sulfur-loaded nano silica is dispersed into water to obtain a suspension, aniline is added to the suspension for polymerization of the aniline, and a sulfur/silica/polyaniline core-shell structure nanocomposite is obtained after the reaction.
4. The preparation method according to claim 3, wherein after the sulfur is evenly mixed with the nano silica, the mixture is heated to no less than 112.8°C under inert atmosphere for calcination to obtain the sulfur-loaded nano silica; preferably, the calcination temperature is 150-160°C, the calcination time is 6-24 h; more preferably, the calcination temperature is 155°C, and the calcination time is 12 h; or the ratio of the mass of the nano silica to the mass of the sulfur is 1:(3-5), and preferably, the ratio of the mass of the nano silica to the mass of the sulfur is 1:4; or the sulfur-loaded nano silica and PVP are added into water and evenly mixed to obtain a suspension; preferably, the ratio of the mass of the sulfur-loaded nano silica to the mass of the PVP is (10-30):(50-150), and more preferably, the ratio of the mass of the sulfur-loaded nano silica to the mass of the PVP is 20:100.
5. The preparation method according to claim 3, wherein a method for preparing the nano silica takes ethanol, water and cyclohexane as cosolvents, CTAB as a surfactant, the PVP as a wrapping agent, ammonia water as a catalyst and TEOS as a silicon source, the components are evenly mixed under conditions of stirring at room temperature, then the mixed solution is transferred to a reaction kettle, silica containing the CTAB and the PVP is prepared through solvothermal reaction, and finally a spherical silica nanomaterial with radial mesoporous channels can be obtained through high-temperature calcination; preferably, the ratio of the volume of the ethanol to the volume of the water to the volume of the cyclohexane is (20-30):(10-20):(3-5); more preferably, the ratio of the volume of the ethanol to the volume of the water to the volume of the cyclohexane is 25:(15-20):4; preferably, the ratio of the mass of the CTAB to the mass of the PVP is (0.06-0.10):(0.020.08), and more preferably, the ratio of the mass of the CTAB to the mass of the PVP is 0.08:0.04; preferably, the ratio of the volume of the TEOS to the volume of the ammonia water is (0.40.6):(0-1); more preferably, the ratio of the volume of the TEOS to the volume of the ammonia water is 0.5:0.5; preferably, the solvothermal reaction temperature is 80-120°C, and more preferably, the solvothermal reaction temperature is 100°C; preferably, the high-temperature calcination temperature is 500-600°C, and more preferably, the high-temperature calcination temperature is 550°C.
6. The preparation method according to claim 3, wherein steps for carrying out the polymerization comprise: adding a hydrochloric acid solution of the aniline into the suspension, mixing evenly, and then adding an initiator for reaction; preferably, after the initiator is added into water for dissolution, the initiator solution is added into the mixed solution of the hydrochloric acid solution of the aniline and the suspension; preferably, the initiator is ammonium persulfate, the input ratio of the aniline to the ammonium persulfate is (10-30):(26-78), RL:mg, and more preferably, the input ratio of the aniline to the ammonium persulfate is 20:52, RL:mg; preferably, the concentration of the hydrochloric acid solution is 0.5-2 mol and more preferably, the concentration of the hydrochloric acid is l mol
7. Use of the composite according to claim 1 or 2 in the preparation of electronic materials, magnetic materials, catalytic materials, sensing materials, photoelectric materials or energy storage materials; and preferably, use of the foregoing composite in a lithium-sulfur battery.
8. A cathode material of a lithium-sulfur battery, comprising the composite according to claim 1 or 2.
9. A lithium-sulfur battery, wherein the cathode material according to claim 8 is used as a cathode, and a lithium sheet is used as an anode.
10. The lithium-sulfur battery according to claim 9, wherein a polypropylene film is used as a separator; or 1,3 dioxolane/dimethoxyethane lithium bis(trifluoromethanesulfonyl)im de is used as an electrolyte.