CN115832251B

CN115832251B - Lithium-sulfur battery positive electrode material and preparation method thereof and lithium-sulfur battery positive electrode sheet

Info

Publication number: CN115832251B
Application number: CN202211550697.0A
Authority: CN
Inventors: 王磊; 马颖; 宋海洋; 李钊; 江浩
Original assignee: Xian Shiyou University
Current assignee: Xian Shiyou University
Priority date: 2022-12-05
Filing date: 2022-12-05
Publication date: 2024-12-24
Anticipated expiration: 2042-12-05
Also published as: CN115832251A

Abstract

The present invention discloses a lithium-sulfur battery positive electrode material and a preparation method thereof, and a lithium-sulfur battery positive electrode sheet, wherein the lithium-sulfur battery positive electrode material comprises a two-dimensional MXene nanosheet encapsulating a bimetallic selenide (45@HZnSe‑CoSe/M) dodecahedral structure, and the electrode material has high specific capacity and long cycle life.

Description

Lithium-sulfur battery positive electrode material, preparation method thereof and lithium-sulfur battery positive electrode plate

Technical Field

The invention relates to the technical field of lithium sulfur batteries, in particular to a lithium sulfur battery positive electrode material, a preparation method thereof and a lithium sulfur battery positive electrode plate.

Background

At present, the demand of the high-performance secondary battery is continuously increased, but the energy density of the traditional lithium ion battery reaches the limit, so that the large breakthrough cannot be realized in a short period, and the demand of people is difficult to meet. Therefore, development of a new secondary battery having higher energy and power density and longer cycle life is required. Among the many new secondary battery systems, lithium-sulfur batteries are considered as one of the most potential efficient energy storage devices of the next generation because of their extremely high theoretical specific capacity (1675 mAh. G ^-1) and theoretical energy density (2600 Wh. Kg ^-1), abundant and low price of active material sulfur, environmental friendliness, and the like.

However, in the development of lithium sulfur batteries, some outstanding problems restrict the development thereof, including poor conductivity of sulfur, volume expansion upon discharge, and shuttle effect caused by the polysulfide produced. Therefore, the search and development of suitable sulfur cathode materials to alleviate the above problems is key to overcoming the difficulties, and is also a hot spot and difficulty of research.

Disclosure of Invention

The invention mainly aims to provide a lithium-sulfur battery positive electrode material, a preparation method thereof and a lithium-sulfur battery positive electrode plate, so as to solve the problem of poor lithium-sulfur battery circularity caused by a shuttle effect and poor elemental sulfur electron/ion conductivity in the charge and discharge process of a lithium-sulfur battery in the prior art.

According to one aspect of the application, a lithium sulfur battery positive electrode material is provided, which comprises a two-dimensional MXene nano-sheet wrapped bimetal selenide (45@HZnSe-CoSe/M) dodecahedron structure.

Wherein HZnSe-CoSe dodecahedron is a porous hollow rhombic dodecahedron, and the average diameter of particles of the porous hollow rhombic dodecahedron is 580nm.

According to another aspect of the application, a preparation method of the lithium sulfur battery positive electrode material is provided, which comprises the steps of preparing a ZIF-8@ZIF-67 dodecahedron, preparing 45@HZIF according to the ZIF-8@ZIF-67 dodecahedron, preparing HZnSe-CoSe porous hollow dodecahedron according to the 45@HZIF, preparing an MXene colloid, mixing the 45@HZnSe-CoSe porous hollow dodecahedron with the MXene colloid to obtain a two-dimensional MXene nano sheet wrapped 45@HZnSe-CoSe dodecahedron (45@HZnSe-CoSe/M), and carrying out seepage treatment on the 45@HZnSe-CoSe/M to obtain the 45@HZnSe-CoSe/M/S composite material.

The preparation method of the ZIF-8@ZIF-67 dodecahedron comprises the steps of dissolving cobalt nitrate hexahydrate (Zn (NO ₃)₂·6H₂ O) and 2-methylimidazole (MeIm) in methanol respectively, mixing the two solutions, obtaining ZIF-8 through white precipitates in the mixed solution, ultrasonically dispersing the ZIF-8 in the methanol to obtain ZIF-8 dispersion liquid, dissolving Co (NO ₃)₂·6H₂ O and MeIm) in the methanol respectively, adding the two solutions into the ZIF-8 dispersion liquid respectively, and obtaining the ZIF-8@ZIF-67 dodecahedron through the precipitates in the mixed solution.

The preparation method of the porous hollow dodecahedron of the HZnSe-CoSe comprises the steps of obtaining ZIF-8@ZIF-67 dispersion liquid according to ZIF-8@ZIF-67, adding tannic acid aqueous solution into the ZIF-8@ZIF-67 dispersion liquid to obtain the dodecahedron of the 45@HZIF, and carrying out selenizing reaction on the 45@HZIF to obtain the porous hollow dodecahedron of the 45@HZnSe-CoSe.

The preparation method of the MXene colloid comprises the steps of mixing Ti ₃AlC₂ -MAX phase ceramic, liF and HCl to obtain mixed solution, stirring the mixed solution to enable HF generated in the mixed solution to etch Al in MAX, washing and centrifuging the mixed solution by deionized water, adding deionized water into precipitation of the mixed solution to carry out ultrasonic treatment, and collecting the MXene colloid on the upper layer of the solution after ultrasonic treatment.

According to a further aspect of the application, a positive plate of a lithium-sulfur battery is also provided, which comprises a current collector and a coating layer coated on the surface of the current collector, wherein the coating layer comprises the 45@HZnSe-CoSe/M/S composite material prepared by the preparation method according to any one of claims 3 to 6.

Wherein the coating layer further comprises carbon black and a binder.

Wherein the mass ratio of the 45@HZnSe-CoSe/M/S composite material, the carbon black and the binder is 7:2:1.

Wherein the mass ratio of the 45@HZnSe-CoSe/M/S composite material, the carbon black and the binder is 6:3:1.

According to the S@Co ₃S₄/CN nano-box positive electrode material, through testing, the discharge capacity is 1299.8 mAh.g ^-1 under the current density of 0.1C, the initial coulomb efficiency is 99.3%, the discharge capacity of 552.7 mAh.g ^-1 can be still kept after 500 cycles under the current density of 1C, the capacity attenuation rate per cycle is only 0.07%, and the electrode material has high specific capacity and long cycle life.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:

FIG. 1 is a flow chart according to one embodiment of the invention;

FIG. 2 is a schematic illustration of the formation of a 45@HZnSe-CoSe/M/S positive electrode material according to an embodiment of the invention;

FIG. 3 is a flow chart according to another embodiment of the present invention;

FIG. 4A is a transmission electron microscope image of a 15@HZIF dodecahedron according to an embodiment of the present invention;

FIG. 4B is a transmission electron microscope image of a 30@HZIF dodecahedron according to an embodiment of the present invention;

FIG. 4C is a transmission electron microscope image of a 45@HZIF dodecahedron according to an embodiment of the present invention;

FIG. 4D is a transmission electron microscope image of a 60@HZIF dodecahedron according to an embodiment of the present invention;

FIG. 4E is a transmission electron microscope image of a 45@HZnSe-CoSe dodecahedron according to an embodiment of the present invention;

FIG. 4F is a transmission electron microscope image of a 45@HZnSe-CoSe/M dodecahedron according to an embodiment of the present invention;

FIG. 5 is a schematic representation of XRD analysis of 15@HZnSe-CoSe, 30@HZnSe-CoSe, 45@HZnSe-CoSe, 60@HZnSe-CoSe according to an embodiment of the invention;

FIG. 6 is a schematic diagram of electrochemical impedance spectroscopy of 15@HZnSe-CoSe/S, 30@HZnSe-CoSe/S, 45@HZnSe-CoSe/S, 60@HZnSe-CoSe/S according to an embodiment of the invention;

FIG. 7 is a schematic diagram of specific capacity and coulombic efficiency curves for a 15@HZnSe-CoSe/S, 30@HZnSe-CoSe/S, 45@HZnSe-CoSe/S, 60@HZnSe-CoSe/S positive electrode material cycled 100 times at 0.2C according to an embodiment of the invention;

FIG. 8 is a schematic representation of the rate capability of 45@HZnSe-CoSe/S and 45@HZnSe-CoSe/M/S positive electrode materials at a current density of 0.1C-2C according to an embodiment of the invention;

FIG. 9 is a schematic diagram of specific capacity and coulombic efficiency curves for 45@HZnSe-CoSe/S and 45@HZnSe-CoSe/M/S positive electrode materials cycled 100 times at 0.2C according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. 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.

The following describes in detail the technical solutions provided by the embodiments of the present invention with reference to the accompanying drawings.

The embodiment of the invention provides a lithium sulfur battery positive electrode material which comprises a bimetal selenide (45@HZnSe-CoSe/M) dodecahedron structure wrapped by two-dimensional MXene nano sheets.

The invention adopts acid etching technology to etch ZIF precursor to form four hollow structures with different degrees, wherein the electrode material obtained has optimal electrochemical performance when etching for 45 minutes, which indicates that too much or too little bimetallic compound can affect the performance of the battery. On the basis of the structure, a conductive two-dimensional material MXene is added to obtain the 45@HZnSe-CoSe/M composite material. The 45@HZnSe-CoSe has a rich pore structure, znSe and CoSe can effectively adsorb lithium polysulfide during charging and discharging, so that the ZnSe and the CoSe are prevented from being dissolved in electrolyte, the shuttle effect is relieved, the electrochemical performance and the cycle life of the material are improved, the hollow structure has a higher specific surface area and a larger space, the volume expansion/contraction of the battery during charging and discharging can be relieved, the two-dimensional MXene coating layer endows the anode material with good electron transmission performance, and the combination of sulfur and lithium can be prevented, so that the electrochemical performance of the material is further improved.

The embodiment of the invention also provides a preparation method of the positive electrode material of the lithium-sulfur battery, and referring to fig. 1 and 2, the method comprises the following steps:

Step S102, preparing a ZIF-8@ZIF-67 dodecahedron, preparing a 45@HZIF according to the ZIF-8@ZIF-67 dodecahedron, and preparing a HZnSe-CoSe porous hollow dodecahedron according to the 45@HZIF.

(1) Firstly, preparing a ZIF-8@ZIF-67 dodecahedron, which specifically comprises the steps of respectively dissolving cobalt nitrate hexahydrate (Zn (NO ₃)₂·6H₂ O) and 2-methylimidazole (MeIm) in 150ml of methanol and stirring for 30 minutes, then rapidly mixing the two solutions and continuing stirring at room temperature for 24 hours, then centrifuging and washing the obtained white precipitate by methanol, drying at 60 ℃ for 12 hours to obtain ZIF-8, then ultrasonically dispersing the ZIF-8 in the methanol to obtain ZIF-8 dispersion liquid which is used as a seed for the growth of ZIF-67, then respectively dissolving Zn (NO ₃)₂·6H₂ O and MeIm) in 100ml of methanol solution, then respectively adding the two solutions into the ZIF-8 dispersion liquid, continuing stirring at room temperature for 24 hours, and finally, centrifuging, washing and drying the precipitate to obtain a bright purple sample, thereby obtaining the ZIF-8@ZIF-67 dodecahedron structure.

(2) A45@HZIF was prepared from a twelve-sided body of ZIF-8@ZIF-67, specifically, 1.0g of ZIF-8@ZIF-67 was ultrasonically dispersed in 2ml of an ethanol solution and stirred for 20 minutes to obtain a ZIF-8@ZIF-67 dispersion, and then, 0.25g of tannic acid was dissolved in 48ml of deionized water and stirred for 30 minutes to obtain an aqueous tannic acid solution. While stirring the ZIF-8@ZIF-67 dispersion at a high speed, slowly adding the tannic acid aqueous solution into the ZIF-8@ZIF-67 dispersion, aging for 45 minutes, and then centrifuging, washing the precipitate with deionized water and methanol, and drying to obtain the 45@HZIF. Under the condition that the steps of preparing the tannic acid aqueous solution and the ZIF-8@ZIF-67 dispersion are the same, the aging time is changed, and the tannic acid aqueous solution is aged for 15 minutes, 30 minutes and 1 hour respectively to obtain 15@HZIF, 30@HZIF and 60@HZIF.

(3) The HZnSe-CoSe porous hollow dodecahedron is prepared according to 45@HZIF, specifically, 0.5g of 45@HZIF material prepared by the method and 1.0g of selenium powder are respectively placed into two dry pans, placed at the downstream and upstream of a tube furnace, and calcined at 800 ℃ for 3 hours under the protection of N ₂, so that the final material 45@HZnSe-CoSe porous hollow rhombic dodecahedron is obtained. The other three materials (15@HZIF, 30@HZIF and 60@HZIF) are also used for obtaining 15@HZnSe-CoSe, 30@HZnSe-CoSe and 60@HZnSe-CoSe composite materials through similar methods, and the detailed description is omitted.

Step S104, preparing MXene colloid, which specifically comprises the following steps:

(1) First, 1.0g LiF was dispersed in a solution containing 5mL deionized water and 15mL HCl (12 mol/L), and then 1.0g Ti ₃AlC₂ (MAX) powder was slowly added to prevent overheating.

(2) Then, the mixed solution in the step (1) is stirred on a magnetic stirrer for 24 hours at constant temperature (35 ℃) to enable HF generated by the reaction to sufficiently etch Al in MAX, and the "A" layer in MAX phase is etched immediately.

(3) After 24 hours, the mixed solution of the step (2) is collected, centrifuged and washed with deionized water for 4-5 times until the pH value of the supernatant of the mixed solution reaches about 6, and the precipitate is collected to obtain stacked multi-layer MXene.

(4) The centrifuged precipitate was collected, 200mL of deionized water was added, followed by sonication for 4 hours, centrifugation at 3500 rpm for 1 hour after sonication was completed, and the upper MXene colloid was collected. By stripping, it is ensured that a single layer of MXene remains on the upper layer, and that several layers which are not stripped remain on the lower layer, and the upper layer colloid is collected for later use, and the lower layer is discarded. Among them, MXene is a two-dimensional lamellar fragment, has negative charges, and is excellent in hydrophilicity, which is called colloid.

And S106, mixing the 45@HZnSe-CoSe porous hollow dodecahedron with the MXene colloid to obtain the 45@HZnSe-CoSe dodecahedron (45@HZnSe-CoSe/M) wrapped by the two-dimensional MXene nano sheet. Wherein, the 45@HZnSe-CoSe dodecahedron has positive charges, and under the electrostatic interaction, the two components of the MXene colloid and the 45@HZnSe-CoSe dodecahedron can be assembled together. Specifically, 45@HZnSe-CoSe is ultrasonically dispersed in methanol, then MXene colloid is added under rapid stirring, the two components are successfully assembled through electrostatic interaction, and finally 45@HZnSe-CoSe/M is collected through centrifugal washing and drying. The MXene sheet layer is coated outside the bimetallic selenide 45@HZnSe-CoSe, so that the conductivity of the battery can be improved, the shuttle effect of polysulfide can be further relieved, and the electrochemical performance of the battery can be improved.

S108, performing sulfurizing treatment on the 45@HZnSe-CoSe/M to obtain the 45@HZnSe-CoSe/M/S composite material. Specifically, the prepared 45@HZnSe-CoSe/M dodecahedron and elemental sulfur were mixed and ground for 30 minutes, and then incubated at 155 ℃ for 12 hours to obtain 45@HZnSe-CoSe/M/S material. The other three materials (15@HZnSe-CoSe, 30@HZnSe-CoSe, 60@HZnSe-CoSe) are also used for obtaining 15@HZnSe-CoSe/S, 30@HZnSe-CoSe/S and 60@HZnSe-CoSe/S composite materials through similar methods, and the detailed description is omitted. The positive electrode material of the lithium-sulfur battery can be prepared by the materials. In the above procedure, milling allows for thorough mixing of the two components, and 155 degrees celsius is chosen because elemental sulfur is the most flowable at this temperature and also the easiest to enter the interstices of the HZnSe-CoSe dodecahedron.

The embodiment of the application also provides a preparation method of the positive plate of the lithium-sulfur battery, and referring to fig. 3, on the basis of the embodiment shown in fig. 1, the method further comprises the following steps:

Step S110, preparing slurry. And (2) mixing and stirring the 45@HZnSe-CoSe/M/S composite material prepared in the step S108 with carbon black and a binder to prepare slurry, wherein the mass ratio of the 45@HZnSe-CoSe/M/S composite material to the carbon black to the binder can be 7:2:1 or 6:3:1.

And step S112, uniformly coating the slurry on a current collector of the positive plate of the lithium-sulfur battery, and drying for 12 hours at 60 ℃ under vacuum to prepare the electrode plate.

The current collector can be metal foil, foam metal, foam carbon, carbon paper, carbon felt or carbon cloth.

The binder may be an oil-soluble binder such as polyvinylidene fluoride, a solvent in which the binder is dissolved is N-methyl-2-pyrrolidone when the binder is an oil-soluble binder, or a water-soluble binder such as polytetrafluoroethylene, polyethylene oxide, LA133, polymethyl methacrylate, beta-cyclodextrin, agar, starch, sodium carboxymethyl cellulose, polybutadiene rubber, styrene butadiene rubber, etc., and water when the binder is a water-soluble binder.

The embodiment of the application also provides a lithium-sulfur battery positive plate which comprises a current collector and a coating layer coated on the surface of the current collector, wherein the coating layer comprises a 45@HZnSe-CoSe/M/S composite material. Wherein the coating layer further comprises carbon black and a binder, and the mass ratio of the 45@HZnSe-CoSe/M/S composite material to the carbon black to the binder is 7:2:1 or 6:3:1.

Referring to fig. 4A-4F, fig. 4A-4D represent the topographical features of the tannic acid etched ZIF-8@zif-67 dodecahedron 15, 30, 45 and 60 minutes, respectively. With the extension of etching time, the morphology of the material can evolve from a shell-core type to a completely hollow structure. Fig. 4E shows the morphology of 45@hznse-CoSe, indicating that the selenization reaction does not affect the structural integrity of the dodecahedron. FIG. 4F shows a morphology of 45@HZnSe-CoSe/M, and a plurality of sheets are coated outside the dodecahedron, which illustrates that the MXene and 45@HZnSe-CoSe materials are successfully compounded. Referring to fig. 5 to 9, the present invention obtains hollow dodecahedron of different degrees by acid etching technology, then prepares HZnSe-CoSe dodecahedron by selenization reaction, and then prepares HZnSe-CoSe/S composite cathode material by a method of sulfurization. It can be seen from the test of four positive electrode materials that the 45@HZnSe-CoSe/S positive electrode material has the smallest charge transfer resistance, the initial specific discharge capacity is 740 mAh.g ^-1 at the current density of 0.2C, the specific discharge capacity still has 386 mAh.g ^-1 after the cycle process of 100 circles, and the coulomb efficiency (coulombic efficiency) is always kept above 98% (the comparison data are detailed in Table 1). This illustrates that the hollow structure electrode obtained by etching for 45 minutes has the most stable cycle life. Therefore, on the basis of 45 minutes of etching, the conductive two-dimensional material MXene is added to obtain the 45@HZnSe-CoSe/M/S positive electrode composite material, and the electrode material is found to have excellent conductivity and rate capability.

TABLE 1

In summary, the positive electrode material for lithium-sulfur batteries according to the embodiments of the present application has at least one of the following advantages:

(1) The two-dimensional layered MXene shows higher catalytic activity in electrochemical reactions.

(2) MXene exhibits excellent adsorptivity to polysulfides during charge and discharge.

(3) The hollow structure has higher specific surface area and space, and can relieve the volume expansion effect.

(4) The porous hollow 45@HZnSe-CoSe/M/S dodecahedron shows higher electrochemical performance.

(5) The porous hollow 45@HZnSe-CoSe/M/S dodecahedron can relieve the shuttle effect.

(6) The 45@HZnSe-CoSe dodecahedron positive electrode material with the surface coated with MXene has good conductivity.

(7) The electrostatic self-assembly technology has the advantages of simple process, strong controllability and good repeatability, thus having wide application prospect.

(8) The electrode prepared by the invention can obtain larger specific discharge capacity and cycle stability after being assembled into a battery.

Although the present disclosure has been described in detail with reference to particular embodiments thereof, those skilled in the art will appreciate that various changes and modifications can be made therein without departing from the spirit and scope of the embodiments. It is therefore intended that the present application cover the modifications and variations of this application provided they come within the spirit and scope of the appended claims and their equivalents.

Furthermore, the features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the application in diverse forms thereof. In particular, one or more features of any one of the embodiments described herein may be combined with one or more features of any other of the embodiments described herein.

Protection may also be sought for any feature disclosed in any one or more of the publications cited in connection with the present application and/or incorporated by reference.

Claims

1. A positive electrode material for a lithium-sulfur battery, characterized in that the positive electrode material for the lithium-sulfur battery comprises a two-dimensional MXene nanosheet wrapped with a bimetallic selenide (45@HZnSe-CoSe/M) dodecahedral structure, wherein the positive electrode material for the lithium-sulfur battery is a hollow structure and is obtained by a 45-minute acid etching technique.

2. The lithium-sulfur battery cathode material according to claim 1, characterized in that the HZnSe-CoSe dodecahedron is a porous hollow rhombic dodecahedron, and the average diameter of the porous hollow rhombic dodecahedron particles is 580 nm.

3. A method for preparing a positive electrode material for a lithium-sulfur battery, characterized by comprising:

Prepare ZIF-8@ZIF-67 dodecahedron, prepare 45@HZIF based on ZIF-8@ZIF-67 dodecahedron, and prepare HZnSe-CoSe porous hollow dodecahedron based on 45@HZIF; wherein preparing 45@HZIF based on ZIF-8@ZIF-67 dodecahedron comprises: slowly adding tannic acid aqueous solution to ZIF-8@ZIF-67 dispersion and aging for 45 minutes to obtain 45@HZIF dodecahedron;

Preparation of MXene colloids;

The 45@HZnSe-CoSe porous hollow dodecahedron was mixed with MXene colloid to obtain two-dimensional MXene nanosheets encapsulating 45@HZnSe-CoSe dodecahedron (45@HZnSe-CoSe/M);

45@HZnSe-CoSe/M was subjected to infiltration treatment to obtain 45@HZnSe-CoSe/M/S composite material.

4. The method according to claim 3, characterized in that the step of preparing ZIF-8@ZIF-67 dodecahedron comprises:

Cobalt nitrate hexahydrate (Zn(NO ₃ ) ₂ ·6H ₂ O) and 2-methylimidazole (MeIm) were dissolved in methanol, respectively, and the two solutions were mixed, and ZIF-8 was obtained through the white precipitate in the mixed solution;

Ultrasonic dispersion of ZIF-8 in methanol was performed to obtain a ZIF-8 dispersion;

Co(NO ₃ ) ₂ ·6H ₂ O and MeIm were dissolved in methanol, respectively, and the two solutions were added to the ZIF-8 dispersion, and ZIF-8@ZIF-67 dodecahedron was obtained by precipitating from the mixed solutions.

5. The method according to claim 3 or 4, characterized in that the step of preparing 45@HZIF according to ZIF-8@ZIF-67 dodecahedron further comprises: obtaining a ZIF-8@ZIF-67 dispersion according to ZIF-8@ZIF-67;

The step of preparing HZnSe-CoSe porous hollow dodecahedron according to 45@HZIF includes: performing selenization reaction on 45@HZIF to obtain 45@HZnSe-CoSe porous hollow dodecahedron.

6. The method according to claim 3, characterized in that the step of preparing MXene colloid comprises:

mixing Ti ₃ AlC ₂ -MAX phase ceramic, LiF and HCl to obtain a mixed solution;

The mixed solution is stirred to allow HF generated in the mixed solution to etch Al in the MAX;

The mixed solution was washed and centrifuged with deionized water;

Deionized water was added to the precipitate of the mixed solution for ultrasonic treatment, and the MXene colloid on the upper layer of the solution after ultrasonic treatment was collected.

7. A lithium-sulfur battery positive electrode plate, characterized in that it comprises: a current collector and a coating layer coated on the surface of the current collector, wherein the coating layer comprises a 45@HZnSe-CoSe/M/S composite material prepared according to the preparation method according to any one of claims 3 to 6.

8 . The lithium-sulfur battery positive electrode sheet according to claim 7 , wherein the coating layer further comprises carbon black and a binder.

9 . The lithium-sulfur battery positive electrode according to claim 8 , wherein the mass ratio of the 45@HZnSe-CoSe/M/S composite material, the carbon black and the binder is 7:2:1.

10 . The lithium-sulfur battery positive electrode sheet according to claim 8 , wherein the mass ratio of the 45@HZnSe-CoSe/M/S composite material, the carbon black and the binder is 6:3:1.