CN116764660A - High-activity positive electrode material catalyst for lithium-sulfur battery and preparation method thereof - Google Patents
High-activity positive electrode material catalyst for lithium-sulfur battery and preparation method thereof Download PDFInfo
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- JDZCKJOXGCMJGS-UHFFFAOYSA-N [Li].[S] Chemical compound [Li].[S] JDZCKJOXGCMJGS-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 230000000694 effects Effects 0.000 title claims abstract description 30
- 239000003054 catalyst Substances 0.000 title claims abstract description 26
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 16
- 238000002360 preparation method Methods 0.000 title abstract description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 32
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 29
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 24
- -1 cyanamide compound Chemical class 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 14
- 239000012298 atmosphere Substances 0.000 claims abstract description 11
- 230000007547 defect Effects 0.000 claims abstract description 8
- 238000010438 heat treatment Methods 0.000 claims description 39
- 229910052751 metal Inorganic materials 0.000 claims description 11
- 239000002184 metal Substances 0.000 claims description 11
- 150000002751 molybdenum Chemical class 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 claims description 7
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 6
- 239000010406 cathode material Substances 0.000 claims description 5
- POILWHVDKZOXJZ-ARJAWSKDSA-M (z)-4-oxopent-2-en-2-olate Chemical compound C\C([O-])=C\C(C)=O POILWHVDKZOXJZ-ARJAWSKDSA-M 0.000 claims description 4
- 230000002950 deficient Effects 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 239000011733 molybdenum Substances 0.000 claims description 4
- UMGDCJDMYOKAJW-UHFFFAOYSA-N thiourea Chemical compound NC(N)=S UMGDCJDMYOKAJW-UHFFFAOYSA-N 0.000 claims description 4
- 229920000877 Melamine resin Polymers 0.000 claims description 2
- 239000004202 carbamide Substances 0.000 claims description 2
- 239000002041 carbon nanotube Substances 0.000 claims description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 8
- 239000003575 carbonaceous material Substances 0.000 abstract description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 7
- 229920001021 polysulfide Polymers 0.000 abstract description 7
- 239000005077 polysulfide Substances 0.000 abstract description 7
- 150000008117 polysulfides Polymers 0.000 abstract description 7
- 239000002994 raw material Substances 0.000 abstract description 5
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 4
- 238000001179 sorption measurement Methods 0.000 abstract description 4
- 238000010000 carbonizing Methods 0.000 abstract description 3
- 239000004020 conductor Substances 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- 229910052717 sulfur Inorganic materials 0.000 abstract description 3
- 239000011593 sulfur Substances 0.000 abstract description 3
- 230000003197 catalytic effect Effects 0.000 abstract description 2
- 238000006555 catalytic reaction Methods 0.000 abstract description 2
- 239000007772 electrode material Substances 0.000 abstract description 2
- 239000002131 composite material Substances 0.000 description 7
- 238000001035 drying Methods 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 238000001000 micrograph Methods 0.000 description 6
- 210000004027 cell Anatomy 0.000 description 5
- 238000011161 development Methods 0.000 description 5
- 239000011888 foil Substances 0.000 description 5
- 239000006245 Carbon black Super-P Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 4
- 238000000498 ball milling Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 229940045638 potassium citrate / sodium citrate Drugs 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000005431 greenhouse gas Substances 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 229910052573 porcelain Inorganic materials 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 241000282414 Homo sapiens Species 0.000 description 1
- 229910013553 LiNO Inorganic materials 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 150000001912 cyanamides Chemical class 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 1
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000002082 metal nanoparticle Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000001508 potassium citrate Substances 0.000 description 1
- 229960002635 potassium citrate Drugs 0.000 description 1
- QEEAPRPFLLJWCF-UHFFFAOYSA-K potassium citrate (anhydrous) Chemical compound [K+].[K+].[K+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O QEEAPRPFLLJWCF-UHFFFAOYSA-K 0.000 description 1
- 235000011082 potassium citrates Nutrition 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000027756 respiratory electron transport chain Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
- B01J37/086—Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a high-activity positive electrode material catalyst for a lithium sulfur battery and a preparation method thereof, wherein the catalyst comprises a flaky nitrogen-doped carbon-based carrier and molybdenum metal nanoclusters uniformly embedded on the surface of the carrier, wherein the molybdenum metal nanoclusters are 1-10nm, the mass ratio of the molybdenum metal nanoclusters on the carrier is 10-20wt%, and the catalyst is used as the positive electrode material of the lithium sulfur battery after being melted into sulfur. The catalyst is prepared by taking a cyanamide compound and an organometallic molybdenum salt as raw materials or continuously adding a carbon material with defects, and directly carbonizing in a tube furnace in an inert atmosphere through full physical mixing. The high-specific-surface-area flaky nitrogen doped carbon conductive material with the uniformly distributed molybdenum metal nanoclusters performs physical adsorption and chemical catalysis on polysulfide formed in the charge-discharge process of the positive electrode side of the lithium-sulfur battery, captures the polysulfide, solves the shuttle effect in the charge-discharge process, and finally improves the electrochemical performance of the electrode material. The specific capacity of the first discharge can reach 1314.2mAh/g, the specific capacity decay is only 20% after 100 times of circulation, and the lithium-sulfur battery catalytic material has wide application prospect.
Description
Technical Field
The invention belongs to the technical field of positive electrode materials of lithium-sulfur batteries, and relates to a high-activity positive electrode material catalyst for a lithium-sulfur battery and a preparation method thereof.
Background
With the rapid development of industrial production and science and technology, the demand of human beings on energy is increased, the energy and the environment are two most important problems in the 21 st century, 80% of energy supply in the current stage is from fossil fuel, greenhouse gases are discharged in the using process of traditional energy, the environment is greatly damaged by pollutants generated by the derivative of the greenhouse gases, and the environment is reduced by using renewable energy. Therefore, new energy development which can replace the traditional energy is becoming a trend. Among them, new energy sources such as wind energy, tidal energy, solar energy, etc. are difficult to meet the production demands of people due to their instability, and in order to meet the increasing demands for renewable energy storage systems, development of batteries having high energy density, long life and high safety has become a necessary trend.
The invention and steadily improving rechargeable Lithium Ion Batteries (LiBs) have brought promise to achieve a fossil fuel free society. However, due to the lithium intercalation electrochemical structure, the formation of lithium dendrites presents a serious safety hazard,the commercial development of the LiBs is basically stagnated, and with the increasing demand for large energy storage systems, the development of LiBs with high specific capacities seems to have reached a bottleneck. Wherein, the lithium sulfur battery taking sulfur as a positive electrode and a metal lithium sheet as a negative electrode has extremely high theoretical energy density (2600 Wh kg -1 ) Specific to theory (1672 mA h g) -1 ) Attention is paid to the lithium-sulfur battery, and the lithium-sulfur battery has the advantages of abundant natural reserve of elemental sulfur, low price, easy acquisition and environmental friendliness, and is expected to be a new generation secondary battery with the highest potential and large-scale application value. However, the current positive electrode side of the lithium sulfur battery still has the problems of low sulfur carrying capacity, low elemental sulfur conductivity, shuttle effect and the like, particularly, the shuttle effect causes a great deal of loss of active substances of the battery, so that the capacity is rapidly attenuated, the cycle life is not ideal, and the practical application of the lithium sulfur battery is restricted. Therefore, how to design and optimize the structure of the electrode, and effectively inhibit the shuttle effect while simplifying the operation, has important significance for the commercial application of the lithium-sulfur battery.
Disclosure of Invention
Aiming at the problems, the invention provides a high-activity cathode material catalyst for a lithium sulfur battery and a preparation method thereof, which take cyanamide compounds and organic metal molybdenum salts as raw materials or continuously add defective carbon materials, and the high-activity cathode material catalyst for the lithium sulfur battery can be obtained by directly carbonizing nitrogen-doped carbon conductive materials with uniformly distributed molybdenum metal clusters in a tube furnace under inert atmosphere through full physical mixing.
The technical scheme of the invention is as follows:
a high-activity positive electrode material catalyst for a lithium sulfur battery comprises a flaky nitrogen-doped carbon-based carrier and molybdenum metal nanoclusters uniformly embedded on the surface of the carrier, wherein the size of the molybdenum metal nanoclusters is 1-10nm, and the mass ratio of the molybdenum metal nanoclusters on the carrier is 10-20wt%.
The nitrogen-doped carbon-based carrier is a heat treatment product of organic molybdenum metal salt and cyanamide compound, or is a heat treatment product of organic molybdenum metal salt, cyanamide compound and a carbon-based carrier with defects, wherein the carbon-based carrier with defects is one or more of porous carbon, graphene oxide and carboxylated carbon nanotubes; the cyanamide compound is melamine, dicyandiamide (DCD), urea or thiourea.
The invention also provides a preparation method of the high-activity cathode material catalyst for the lithium-sulfur battery, which comprises the following steps:
(1) Mechanically mixing organic molybdenum metal salt and cyanamide compound uniformly, or continuously adding a carbon-based carrier with defects, and mechanically mixing uniformly; the mass ratio of the organic metal molybdenum salt to the cyanamide compound is 1:10-1:1000;
(2) And (3) heating the mixture obtained in the step (1) in an inert atmosphere for heat treatment to obtain the catalyst (the high-activity anode material catalyst for the lithium sulfur battery) with the nitrogen-doped carbon-based carrier and the uniform molybdenum metal nanoclusters inlaid on the surface of the carrier.
Further, the mechanical mixing is performed by ball milling or manual grinding.
Further, the mass ratio of the defective carbon-based carrier to the organic metal molybdenum salt is 1:5-1:50.
Further, the cyanamide compound is dicyandiamide.
Further, the organic metal molybdenum salt is molybdenum acetylacetonate.
Further, the mass ratio of the organic metal molybdenum salt to the cyanamide compound is 1:50-1:500.
Further, in the step (2), the mixture is heated in an inert atmosphere to perform a heat treatment process, wherein the heat treatment temperature in the first stage is 250-350 ℃, the heat treatment time is 1-4 hours, the heat treatment temperature in the second stage is 450-700 ℃, the heat treatment time is 1-4 hours, the heat treatment temperature in the third stage is 700-1000 ℃, and the heat treatment time is 0.5-3 hours.
Further, the mixture in the step (2) is heated in an inert atmosphere to perform a heat treatment process, wherein the heat treatment temperature in the first stage is 300-350 ℃, the heat treatment time is 2-3 hours, the heat treatment temperature in the second stage is 550-650 ℃, the heat treatment time is 3-4 hours, the heat treatment temperature in the third stage is 750-950 ℃, and the heat treatment time is 1-2 hours.
Further, the inert atmosphere is high-purity nitrogen.
Further, the size of the molybdenum metal clusters is precisely controlled according to the ratio of the organic molybdenum metal salt to dicyandiamide.
The invention also provides application of the catalyst in a high-activity positive electrode material for a lithium-sulfur battery.
The beneficial effects of the invention include:
the invention takes cyanamide compound and organic metal molybdenum salt as raw materials, or continuously adds carbon materials with defects, and the nitrogen doped conductive carbon materials with uniformly distributed molybdenum metal clusters can be obtained by fully and physically mixing and directly carbonizing in a tube furnace under inert atmosphere. The conductive carbon material prepared by the invention has a macroscopically abundant pore structure, a three-dimensional conductive network and a microscopic morphology similar to a graphene structure, has a higher specific surface area, is thinner in carbon layer, has a physical adsorption effect on polysulfide, and has a chemical adsorption and catalytic conversion effect on polysulfide by molybdenum metal nano particles (nanoclusters) inlaid on the surface of the carbon layer. The method is favorable for lithium ion and electron transfer, has physical adsorption and chemical catalysis effects on polysulfide formed in the charge-discharge process in the anode side of the lithium-sulfur battery, effectively captures polysulfide, inhibits the shuttle effect of polysulfide, improves the electrochemical stability, the multiplying power performance and the coulomb efficiency of the battery, and finally improves the electrochemical performance of the electrode material.
The material is applied to a lithium sulfur battery, effectively solves the problems of serious shuttle effect and the like in the lithium sulfur battery, improves the cycle stability and the rate capability of the battery, and shows excellent electrochemical performance. The material is used as the positive electrode of the lithium-sulfur battery, and after the material is circulated for 100 circles under the current density of 0.2C, the specific capacity is 1038.4mA h g -1 The capacity loss rate of each circle is 0.2%, and the coulomb efficiency is close to 100%; after the aluminum foil circulates for 100 circles under the current density of 0.2C, the specific capacity is only 399.2mA h g -1 . In the rate performance test, the specific capacity of the electrode loaded with the molybdenum metal nanocluster nitrogen-doped carbon material is maintained at 690.2mA h g under the current density of 2.0C -1 When the current density recoversWhen the temperature is returned to 0.2 ℃, the specific capacity can be kept at 1086.6mA h g -1 The method comprises the steps of carrying out a first treatment on the surface of the The specific capacity of the aluminum foil electrode is kept at 427.3mA h g under the current density of 2.0C -1 When the current density is recovered to 0.2C, the specific capacity can be kept at 605.7mA h g -1 The specific capacity drops faster.
Drawings
FIG. 1 is a scanning electron microscope image at a magnification of 4000 of the Mo/NC material prepared in example 1.
FIG. 2 is a scanning electron microscope image of the Mo/NC material prepared in example 1 at a magnification of 15000.
FIG. 3 is a transmission electron microscope image of the Mo/NC material prepared in example 1 at a magnification of 1.0M.
FIG. 4 is a transmission electron microscope image at a magnification of 1.2M of the Mo/NC material prepared in example 1.
Fig. 5 is a graph of the cycling performance of the example 1 assembled Mo/NC electrode lithium sulfur cell and the comparative cell at a current density of 0.2C.
Fig. 6 is a graph showing the rate performance of the lithium sulfur battery and the comparative battery in which the Mo/NC electrode is assembled in example 1.
FIG. 7 is a scanning electron microscope image of the Mo/NC material prepared in example 2.
Detailed Description
Specific experimental protocols of the present invention will be described in detail with reference to specific examples, but the present invention is not limited to the examples. Unless specified, the method is a conventional method, and all raw materials and instruments used can be purchased in the market.
Example 1
Respectively weighing 20g dicyandiamide and 0.2g molybdenum acetylacetonate in a reagent bottle according to the mass ratio (100:1), adding 200ml ethanol, mechanically stirring and dispersing, placing a centrifugal machine at 5000r/min for drying at 60 ℃ in a blast drying oven after particles are uniformly dispersed, ball milling for about 12 hours by using a ball mill, uniformly mixing the two precursors, placing the mixture in a tubular furnace, taking high-purity argon as inert shielding gas, heating to 300 ℃ from the initial temperature of 30 ℃ in the whole process at the heating rate of 2 ℃/min, carrying out heat treatment for 2 hours, then continuously heating to 600 ℃, continuously heating to 900 ℃ again, carrying out heat treatment for 3 hours, and cooling to room temperature in an inert atmosphere to obtain a nitrogen-doped conductive carbon material (a high-activity anode material catalyst for lithium sulfur batteries) with uniformly distributed molybdenum metal clusters, wherein the overall appearance of the carbon-loaded molybdenum metal nano-cluster catalyst can be seen by using a scanning electron microscope at the multiple of 4000 as shown in figures 1-4; FIG. 2 is a scanning electron microscope image of the Mo/NC material prepared in example 1 at a multiple of 15000, and can show that the material has a macroscopically abundant pore structure, a three-dimensional conductive network, a microstructure with a graphene-like structure and a higher specific surface area; fig. 3 and fig. 4 are transmission electron microscope diagrams of the Mo/NC material prepared in example 1 under ultra high power, and it can be clearly seen that the thin carbon layer surface having a graphene-like structure is inlaid with uniform molybdenum metal clusters, and the size of the metal clusters is about 1-3nm.
Mixing and grinding sublimed sulfur and Mo/NC conductive material according to the mass ratio of 3:1, placing the mixture into a reaction kettle, vacuumizing, transferring the reaction kettle into a muffle furnace, and carrying out heat preservation for 12h at the melting temperature of 155 ℃ and the heating rate of 5 ℃/min to obtain the Mo/NC@S composite material.
Mixing the prepared Mo/NC@S composite material with Super-P and polyvinylidene fluoride (PVDF) according to a mass ratio of 7:2:1, mixing, preparing slurry by taking N-methyl pyrrolidone (NMP) as a solvent, scraping and coating on aluminum foil, putting the scraped aluminum electrode slice into a vacuum drying oven for drying for 10 hours, and punching into a pole slice by using a punching machine. Assembling in a glove box filled with argon, wherein an electrode plate of the scraped slurry is used as a positive electrode, a lithium plate is used as a negative electrode, a Celgard2325 polypropylene film is used as a battery diaphragm, and 1M LiTFSI/DOL is DMC (1:1) +1%LiNO 3 The electrolyte is assembled into a button cell. The comparative cell was prepared by grinding sublimed sulfur with Super-P to a Super-P@S composite by mixing Super-P@S composite with polyvinylidene fluoride (PVDF) in a mass ratio of 9:1, preparing slurry after mixing, and assembling the same with the other processes into a button cell by using a glove box. After the battery is kept stand for 12 hours, the constant current charge-discharge cycle performance and the multiplying power performance are completed through a blue electric testing system, and the testing voltage window is 1.7-2.8V. The current densities of the rate performance tests were 0.2C,0.5C,1.0C,2.0C (1c=1675 mA h g -1 ). FIG. 5 shows a real objectExample 1 cycle performance graphs of assembled Mo/NC@S composite electrode and comparative battery at 0.2C current density after 100 cycles of Mo/NC@S composite electrode at 0.2C current density, specific capacity was 1038.4mA h g -1 The capacity loss rate of each circle is 0.20%, and the coulomb efficiency is close to 100%; after the aluminum foil electrode circulates for 100 circles under the current density of 0.2C, the specific capacity is only 399.2mA h g -1 The capacity loss per turn was 0.50% and the coulombic efficiency was very low. As shown in FIG. 6, in the rate performance test, the specific capacity of the Mo/NC@S composite material electrode is maintained at 690.2mA h g at a current density of 2.0C -1 When the current density is recovered to 0.2C, the specific capacity can be kept at 1086.6mA h g -1 The specific capacity of the aluminum foil electrode is kept at 427.3mA h g under the current density of 2.0C -1 When the current density is recovered to 0.2C, the specific capacity can be kept at 605.7mA h g -1 The specific capacity drops faster. From the above data, it can be seen that uniformly distributed molybdenum metal nanoclusters can significantly improve electrochemical stability, rate capability and coulombic efficiency of the battery.
Example 2
Weighing potassium citrate/sodium citrate (6.12 g of potassium citrate and 5.16g of sodium citrate) in a porcelain boat, putting the porcelain boat into an oven for drying for 1 hour, removing water in raw materials, putting the dried potassium citrate/sodium citrate in a tubular furnace, and pyrolyzing the dried potassium citrate/sodium citrate in an argon atmosphere at a heating rate of 5 ℃/min in the whole course at 800 ℃ for 1 hour. The inorganic impurities were removed with HCl solution (1M) and water (18.2 mΩ). After drying at 60 ℃, a porous carbon support with defects was obtained.
Respectively weighing 20g dicyandiamide and 0.2g molybdenum acetylacetonate in a reagent bottle in a mass ratio of 100:1, adding 200ml ethanol, mechanically stirring and dispersing, standing at 5000r/min by a centrifugal machine, drying at 60 ℃ by a blast drying oven, adding porous carbon with a mass ratio of 1:5 to the organic metal molybdenum salt, transferring to a ball milling tank together, ball milling for about 12 hours by using a ball mill to uniformly mix the two materials, placing in a tubular furnace, taking argon as inert protective gas, heating to 300 ℃ from an initial temperature of 30 ℃ for 2 hours at the whole process, continuing to heat-treat to 600 ℃ for 2 hours, then heating to 900 ℃ again, cooling to room temperature under an inert atmosphere, and obtaining the Mo/NC of the nitrogen doped conductive carbon material (the high-activity positive electrode material catalyst for the lithium sulfur battery) with uniformly distributed molybdenum metal clusters, as shown in figure 7.
Claims (8)
1. A high-activity positive electrode material catalyst for a lithium sulfur battery is characterized in that: comprises a flaky nitrogen-doped carbon-based carrier and molybdenum metal nanoclusters uniformly embedded on the surface of the carrier, wherein the size of the molybdenum metal nanoclusters is 1-10nm, and the mass ratio of the molybdenum metal nanoclusters on the carrier is 10-20wt%.
2. The high-activity positive electrode material catalyst for lithium-sulfur batteries according to claim 1, wherein: the nitrogen-doped carbon-based carrier is a heat treatment product of an organic molybdenum metal salt and a cyanamide compound, or is a heat treatment product of an organic molybdenum metal salt, a cyanamide compound and a carbon-based carrier with defects; the defective carbon-based carrier is one or more of porous carbon, graphene oxide and carboxylated carbon nanotubes; the cyanamide compound is melamine, dicyandiamide, urea or thiourea.
3. A method for preparing the high-activity cathode material catalyst for the lithium-sulfur battery as claimed in claim 1, which is characterized by comprising the following steps:
(1) Mechanically mixing organic molybdenum metal salt and cyanamide compound uniformly, or continuously adding a carbon-based carrier with defects, and mechanically mixing uniformly; the mass ratio of the organic metal molybdenum salt to the cyanamide compound is 1:10-1:1000;
(2) And (3) heating the mixture obtained in the step (1) in an inert atmosphere for heat treatment, and obtaining the high-activity positive electrode material catalyst for the lithium-sulfur battery.
4. The method for preparing a high-activity positive electrode material catalyst for lithium-sulfur batteries according to claim 3, wherein said organometallic molybdenum salt is molybdenum acetylacetonate.
5. The method for preparing the high-activity positive electrode material catalyst for lithium-sulfur batteries according to claim 3, wherein: the mass ratio of the organic metal molybdenum salt to the cyanamide compound is 1:50-1:500.
6. The method for preparing a high-activity positive electrode material catalyst for lithium-sulfur batteries according to claim 3, wherein the mass ratio of the defective carbon-based carrier to the organometallic molybdenum salt is 1:5 to 1:50.
7. The method for preparing the high-activity positive electrode material catalyst for lithium-sulfur batteries according to claim 3, wherein: in the step (2), the mixture is heated in an inert atmosphere to perform a heat treatment process, wherein the heat treatment temperature of the first stage is 250-350 ℃, the heat treatment time is 1-4 hours, the heat treatment temperature of the second stage is 450-700 ℃, the heat treatment time is 1-4 hours, the heat treatment temperature of the third stage is 700-1000 ℃, and the heat treatment time is 0.5-3 hours.
8. Use of the catalyst of claim 1 or 2 in a high activity cathode material for lithium sulfur batteries.
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