CN104064738B - The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole - Google Patents

The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole Download PDF

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CN104064738B
CN104064738B CN201410299849.3A CN201410299849A CN104064738B CN 104064738 B CN104064738 B CN 104064738B CN 201410299849 A CN201410299849 A CN 201410299849A CN 104064738 B CN104064738 B CN 104064738B
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sulfur
porous carbon
graphene
carbon composite
slurry
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CN104064738A (en
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贾铮
李振华
韦华宇
李程远
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Harbin Institute of Technology
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The hydrothermal preparing process of graphene coated sulfur/porous carbon composite, it relates to the preparation method of the graphene coated sulfur/porous carbon composite of lithium-sulfur rechargeable battery anode material.The present invention is to solve the technical problem that the chemical property of the S-containing composite of existing lithium sulfur battery anode material graphene coated is low.The hydrothermal preparing process of the present invention: after sulfur/porous carbon composite mixes dispersion with Graphene slurry or graphene oxide slurry, Hydrothermal Synthesis prepares hydrogel post, prepares after drying.Graphene coated sulfur/the porous carbon composite using hydrothermal method of the present invention to prepare is the outer surface coated graphite alkene lamella at sulfur/porous carbon composite granule, and forming graphene conductive network between particles, the graphene coated sulfur/porous carbon composite of gained possesses classification nucleocapsid structure.This positive electrode possesses height ratio capacity, long circulation life and good high rate capability.Can be used for lithium secondary battery does positive electrode.

Description

The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole
Technical field
The invention belongs to lithium secondary battery field, be specifically related to use hydro-thermal cross-linking process to prepare graphene coated sulfur/porous carbon multiple The method of condensation material and the application in lithium-sulfur cell thereof.
Background technology
Along with technological revolution and intelligent, the fast development of mobile electronic equipment of new energy field, for electric motor car, storage The battery of energy and electronic product is researched and developed to cause and is paid high attention to widely.The lithium ion battery of the absolute leading position in occuping market at present Because theoretical capacity that embedding lithium anode material is limited cannot meet the requirement of high-energy-density, a new generation's height ratio capacity, high power are forthright Energy, the positive electrode material of lithium secondary cell of high safety performance become the key of battery industry upgrading.The theoretical specific capacity of elemental sulfur (1675mAh g-1) far above embedding lithium anode material (200-300mAh g-1), relatively low running voltage (is born relative to lithium Pole 2.1V) improve the safety of battery, sulfur also has rich reserves, advantage cheap, eco-friendly, under becoming The first-selected positive electrode of generation lithium battery.But, the electronic conductivity of elemental sulfur itself is low (is 5 × 10 at 25 DEG C-30S cm-1), The change in volume of discharging product is big (80%), and electric discharge intermediate product (many lithium sulfides) is soluble in organic electrolyte solution and causes work Property the running off and the charging shuttle effect of positive and negative interpolar of material, the actual capacity that these problems result in lithium-sulfur cell is low, circulation Poor performance, seriously constrains the actual application of battery.
For solving the problems referred to above, an important method is to disperse elemental sulfur to form sulfur/porous carbon composite wood in porous carbon materials Material, its effect is the conductive network on the one hand forming carbon, improves the electron conduction of sulfur, improves the active material utilization of sulfur, On the other hand the pore structure that porous carbon is abundant limits electric discharge intermediate product (many lithium sulfides) loss in electrolyte, changes It is apt to the cycle performance of electrode.But, the electric conductivity of most porous carbon materials is relatively poor, and is distributed in material with carbon element appearance The sulfur in face more increases the contact resistance between sulfur/porous carbon composite granule, causes electrode high rate performance relatively low；It addition, The only confinement effect by material with carbon element hole is difficult to thoroughly suppress the loss by dissolution of many lithium sulfides, cycle performance can't reach practical Degree.
Graphene and graphene oxide, as monoatomic layer C film two-dimensional material, can be used for being coated with sulphurous materials, by In higher electron conduction, the sulphurous materials of (oxidation) graphene coated can improve material active material utilization and times Rate performance；It addition, the cladding of (oxidation) Graphene is relatively compact, can limit to a certain extent many lithium sulfides intermediate product from Positive pole interval migration is run off.
But, in general, no matter it is used alone one layer of porous carbon and does the carrier of sulfur, be also single use one layer (oxidation) Sulfur is coated with by Graphene, the carbonaceous conductive network formed still inadequate even compact, the active material utilization of material, times Rate performance and cycle performance are the most not fully up to expectations.In order to solve this problem, the China of Publication No. CN103560235A is specially Profit proposes and is coated with graphene sheet layer again on the surface of sulfur/porous carbon composite granule, by porous carbon and Graphene Double grading nucleocapsid structure improves the active material utilization of material, high rate performance and cycle performance, achieves certain effect Really, but despite of that, this material first discharge specific capacity under 0.1C multiplying power is 1300～1359mAh g-1, with sulfur Theoretical specific capacity is compared still no small gap, still has certain capacity attenuation, therefore, also have and change further in cyclic process The necessity entered.
Therefore, need badly at present development technology simply efficiently, environmental friendliness, there is height ratio capacity, long circulation life and the highest The preparation method of the sulfur/carbon composite anode material of high rate performance.
Summary of the invention
The present invention is to solve the technical problem that the chemical property of existing graphene coated S-containing composite is low, and provide The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole.
The hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of the present invention sequentially includes the following steps:
One, Graphene slurry is prepared: described Graphene slurry is made up of Graphene and water, and graphene sheet layer is the most uniform Ground dispersion；Wherein, the water content of this Graphene slurry is 90%～99.99%；
Two, prepare sulfur/porous carbon composite, wherein porous carbon materials by activated carbon, Graphene, white carbon black, CNT, A kind of or the most several composition in templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon, sulfur/porous carbon is combined In material, sulfur is 1:(0.02～20 with the mass ratio of porous carbon)；
Three, be (0.02～20) by the mass ratio of the sulfur in the Graphene in Graphene slurry and sulfur/porous carbon composite: 1, general Sulfur/porous carbon composite prepared by step 2 joins to mix in Graphene slurry prepared by step one and is uniformly dispersed, and then will Mixed slurry adds and has in teflon-lined hydrothermal reaction kettle, by after airtight for reactor at 100～220 DEG C of hydro-thermals Reason 1～24h, obtains hydrogel post, rolls extrusion moisture therein, then the washing that is soaked in water after being taken out by hydrogel post, It is dried 1～24h at a temperature of 20～90 DEG C, is ground into powder, then at 20～90 DEG C, be vacuum dried 1～24h, obtain stone Ink alkene cladding sulfur/porous carbon composite.
Wherein the concrete preparation method of the Graphene slurry in step one is as follows:
(1) graphite and reducing agent are weighed；Wherein graphite is 1:(0.1～1000 with the mass ratio of reducing agent)；Reducing agent is Vitamin C A kind of or the most several combination in acid, KOH, NaOH, LiOH and ammonia；
(2) graphite oxidation that step (1) weighs is become graphite oxide；
(3) it is 0.01mg mL by the concentration of graphite oxide-1～50mg mL-1, graphite oxide step (2) obtained adds In water, peel off under the ultrasound condition that frequency is 20～100KHz, disperse 0.5～10h, obtain graphene oxide water-dispersible Liquid；
(4) under conditions of temperature is 4 DEG C～100 DEG C, add in the graphene oxide aqueous dispersions that step (3) obtains Reducing agent, under the ultrasound condition that frequency is 20～100KHz, reduction 0.2h～24h, obtains Graphene aqueous dispersions；
(5) the Graphene aqueous dispersions that step (4) obtains is carried out vacuum filtration, or decompression rotary evaporation, or rotate Centrifugal treating, forms the slurry of thickness, the most again it is carried out dialysis or vacuum filtration washing, obtain steady in a long-term, stone Ink alkene lamella is starched at the scattered Graphene of water camber；The water content of this Graphene slurry is 90%～99.99%.
In step one the Graphene slurry of preparation be a kind of steady in a long-term, Graphene in the way of few number of plies at water camber Homodisperse slurry, this slurry is made up of Graphene and water.Owing to described Graphene is by the chemical reduction method of graphite oxide Prepare, graphene sheet layer exists between a certain amount of electronegative oxygen-containing functional group, these electronegative oxygen-containing functional groups Electrostatic repulsion make Graphene keep high degree of dispersion state in water with few number of plies structure, and this slurry can be 3～4 The homogeneously dispersed state of stable for extended periods of time in individual month, is advantageously implemented uniform on sulfur/porous carbon surface of the Graphene of few number of plies Cladding.
In step 2, described sulfur/porous carbon composite is that sulphur content is dispersed on the surface of porous carbon materials and is formed in hole , wherein, porous carbon by activated carbon, Graphene, white carbon black, CNT, templated porous carbon, carbon fiber, carbon aerogels, A kind of or the most several composition in carbide-derived carbon.The mass ratio of sulfur and porous carbon is 1:(0.02～20).
In step 2, described sulfur/porous carbon composite can be prepared by following several method:
(1) melted diffusion method: by sulfur and porous carbon mix homogeneously, mixture is placed in normal pressure or the environment under high pressure of inert atmosphere Under, or be placed under vacuum environment, at 100～400 DEG C, heat 1h～24h, make sulfur melt in the hole being diffused into porous carbon And outer surface, obtain sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20)；
(2) sulfur steam completion method: elemental sulfur is heated in inert atmosphere or vacuum environment 100～500 DEG C and is sublimed into sulfur steaming Vapour, sulfur steam is filled in neighbouring porous carbon, condenses subsequently, obtains sulfur/porous carbon composite, wherein sulfur and porous carbon Mass ratio be 1:(0.02～20)；
(3) sulphur-containing solution infusion process: sulfur is dissolved in Carbon bisulfide, benzene, toluene, dimethyl sulfoxide, carbon tetrachloride, second In the solvent of a kind of or the most several composition in ether, chloroform, form sulphur-containing solution, porous carbon is added in sulphur-containing solution and soak Stain, is subsequently dried removal solvent, makes sulfur deposit in the hole of porous carbon and on outer surface, obtains sulfur/porous carbon composite, Wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20)；
(4) chemical reaction method: porous carbon is joined dispersion mixing in the aqueous solution of thiosulfate or sulfide uniform, make Thiosulfate or sulfide are impregnated into the pore interior of porous carbon, add dilute acid soln, make thiosulfate or sulfide send out Biochemical reaction, elemental sulfur in porous carbon hole and in outside deposition, obtain sulfur/porous carbon composite, wherein sulfur and The mass ratio of porous carbon is 1:(0.02～20).
In step 3, the Graphene in mixed slurry lower is reduced further hydrothermal, meanwhile, and hydrothermal reaction kettle In mixed slurry be transformed into the water of cylindrical graphene coated sulfur/porous carbon composite of the water of clarification and the centre that is in water Gel column, the hydrogel post of described graphene coated sulfur/porous carbon composite is by under hydro-thermal self-generated pressure and hot conditions The three-dimensional cross-linked Graphene porous network being self-assembly of, the sulfur/porous carbon composite being wrapped in Graphene porous network, And the large quantity of moisture composition being distributed in porous network；This hydrogel post is all solid matters in mixed slurry and certain The cylinder being self-assembly of after amount moisture hydrothermal treatment, separates out after hydrothermal treatment consists from mixed slurry, and except this water-setting Mixed slurry only leaves outside glue post the water of clarification；Due to hydro-thermal self assembly effect, graphene coated sulfur/porous carbon is combined In the hydrogel post of material, various materials distribute very evenly, Graphene three-dimensional cross-linked formation micro/nano level porous network, by sulfur/ Porous carbon composite is uniformly coated with wherein, wherein fills large quantity of moisture, additionally in hydro-thermal self-generated pressure and hot conditions simultaneously Under, the big π bond energy of conjugation of graphenic surface reaches and in sulfur/porous carbon composite, the conjugatedπbond of material with carbon element graphite microcrystal is formed π-π adelphotaxy, makes a considerable amount of fixing crosslink sites of sulfur/set up between porous carbon composite and Graphene, and sulfur/ Porous carbon composite is fixed in " half cage " formed by Graphene.
Described graphene coated sulfur/porous carbon composite is that the hydrogel post of graphene coated sulfur/porous carbon composite exists The composite formed after removing moisture drying, inherits the graphite of the hydrogel post of graphene coated sulfur/porous carbon composite The three-dimensional cross-linked clad structure of alkene, at the outer surface coated graphite alkene lamella of sulfur/porous carbon composite granule, and at Graphene bag Three-dimensional cross-linked graphene conductive network is formed between the sulfur covered/porous carbon composite granule；Sulfur/the porous of this graphene coated Carbon composite possesses classification nucleocapsid structure, and sulfur/porous carbon composite is kernel, and it is multiple that Graphene is then coated on sulfur/porous carbon The outer surface of condensation material granule becomes the protection shell of " half cage " shape, makes the most lithium sulfides of the product in discharge process be limited In " half cage ", it is possible to the effectively loss by dissolution of the suppression electric discharge many lithium sulfides of intermediate product；Wherein, sulfur/porous carbon composite wood Material is that sulphur content is dispersed on the surface of porous carbon materials and is formed in hole, and porous carbon is by activated carbon, Graphene, white carbon black, carbon A kind of or the most several composition in nanotube, templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon；Graphite In alkene cladding sulfur/porous carbon composite, the mass ratio of sulfur, porous carbon and graphene coated layer is 1:(0.02～20): (0.02～20).
The hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of the present invention also can sequentially include the following steps:
One, graphene oxide slurry is prepared: described graphene oxide slurry is made up of graphene oxide, water and ethanol, oxidation Graphene sheet layer is uniformly dispersed in graphene oxide slurry；Wherein, the containing of graphene oxide in this graphene oxide slurry Amount is 0.01mg mL-1～100mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.001mL mL-1～0.1mL mL-1；
Two, prepare sulfur/porous carbon composite, wherein porous carbon materials by activated carbon, Graphene, white carbon black, CNT, A kind of or the most several composition in templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon, sulfur/porous carbon is combined In material, sulfur is 1:(0.02～20 with the mass ratio of porous carbon)；
Three, by the mass ratio of the graphene oxide in graphene oxide slurry with the sulfur in sulfur/porous carbon composite it is (0.04～40): 1, sulfur/porous carbon composite step 2 prepared joins in graphene oxide slurry prepared by step one mixed Conjunction is uniformly dispersed, and is then added by mixed slurry and has in teflon-lined hydrothermal reaction kettle, after airtight for reactor In 100～220 DEG C of hydrothermal treatment consists 1～24h, obtain hydrogel post, after being taken out by hydrogel post, roll extrusion moisture therein, Be soaked in water washing, is dried 1～24h, is ground into powder, then vacuum is done at 20～90 DEG C at a temperature of 20～90 DEG C Dry 1～24h, obtain graphene coated sulfur/porous carbon composite.
Wherein the concrete preparation method of the graphene oxide slurry in step one is as follows:
(1) a certain amount of graphite oxidation is become graphite oxide；
(2) graphite oxide that step (1) obtains is added to the water, peel off under the ultrasound condition that frequency is 20～100KHz, Dispersion 0.5～10h, obtains graphene oxide aqueous dispersions；
(3) in the graphene oxide aqueous dispersions that step (1) obtains, add a certain amount of ethanol, be 20～100KHz in frequency Ultrasound condition under disperse 0.5～10h, obtain graphene oxide slurry；Wherein, graphite oxide in this graphene oxide slurry The content of alkene is 0.01mg mL-1～100mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.001mL mL-1~ 0.1mL mL-1。
In step one the graphene oxide slurry of preparation be a kind of steady in a long-term, graphene oxide with few number of plies structure molten The homodisperse slurry of agent camber, this slurry is made up of graphene oxide, water and ethanol.Due on graphene oxide lamella The electrostatic repulsion existed between the most electronegative oxygen-containing functional group, these electronegative oxygen-containing functional groups makes oxygen Functionalized graphene keeps high degree of dispersion state in a solvent with few number of plies structure, and this slurry can be protected in 3～4 months for a long time Keep steady fixed homogeneously dispersed state, is advantageously implemented the Graphene uniform cladding on sulfur/porous carbon surface of few number of plies.
In step 2, described sulfur/porous carbon composite is that sulphur content is dispersed on the surface of porous carbon materials and is formed in hole , wherein, porous carbon by activated carbon, Graphene, white carbon black, CNT, templated porous carbon, carbon fiber, carbon aerogels, A kind of or the most several composition in carbide-derived carbon.The mass ratio of sulfur and porous carbon is 1:(0.02～20).
In step 2, described sulfur/porous carbon composite can be prepared by following several method:
(1) melted diffusion method: by sulfur and porous carbon mix homogeneously, mixture is placed in normal pressure or the environment under high pressure of inert atmosphere Under, or be placed under vacuum environment, at 100～400 DEG C, heat 1h～24h, make sulfur melt in the hole being diffused into porous carbon And outer surface, obtain sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20)；
(2) sulfur steam completion method: elemental sulfur is heated in inert atmosphere or vacuum environment 100～500 DEG C and is sublimed into sulfur steaming Vapour, sulfur steam is filled in neighbouring porous carbon, condenses subsequently, obtains sulfur/porous carbon composite, wherein sulfur and porous carbon Mass ratio be 1:(0.02～20)；
(3) sulphur-containing solution infusion process: sulfur is dissolved in Carbon bisulfide, benzene, toluene, dimethyl sulfoxide, carbon tetrachloride, second In the solvent of a kind of or the most several composition in ether, chloroform, form sulphur-containing solution, porous carbon is added in sulphur-containing solution and soak Stain, is subsequently dried removal solvent, makes sulfur deposit in the hole of porous carbon and on outer surface, obtains sulfur/porous carbon composite, Wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20)；
(4) chemical reaction method: porous carbon is joined dispersion mixing in the aqueous solution of thiosulfate or sulfide uniform, make Thiosulfate or sulfide are impregnated into the pore interior of porous carbon, add dilute acid soln, make thiosulfate or sulfide send out Biochemical reaction, elemental sulfur in porous carbon hole and in outside deposition, obtain sulfur/porous carbon composite, wherein sulfur and The mass ratio of porous carbon is 1:(0.02～20).In step 3, the graphene oxide in mixed slurry lower is gone back hydrothermal Former one-tenth Graphene, meanwhile, the mixed slurry in hydrothermal reaction kettle is transformed into water and the cylindrical stone of the centre that is in water of clarification The hydrogel post of ink alkene cladding sulfur/porous carbon composite；The hydrogel post of this graphene coated sulfur/porous carbon composite be by The three-dimensional cross-linked Graphene porous network that is self-assembly of under hydro-thermal self-generated pressure and hot conditions, it is wrapped in Graphene porous web Sulfur/porous carbon composite in network, and the large quantity of moisture composition being distributed in porous network；This hydrogel post is mixing slurry The cylinder being self-assembly of after all solid matters in material and a certain amount of moisture hydrothermal treatment, from mixed after hydrothermal treatment consists Close in slurry and separate out, and mixed slurry only leaves in addition to this hydrogel post the water of clarification；Due to hydro-thermal self assembly effect, In the hydrogel post of graphene coated sulfur/porous carbon composite, various materials distribute very evenly, the three-dimensional cross-linked formation of Graphene Micro/nano level porous network, is coated with sulfur/porous carbon composite wherein, wherein fills large quantity of moisture, additionally in hydro-thermal simultaneously Under self-generated pressure and hot conditions, the conjugation big π bond energy of graphenic surface reaches and material with carbon element graphite in sulfur/porous carbon composite The conjugatedπbond of crystallite forms π-π adelphotaxy, makes sulfur/set up between porous carbon composite and Graphene a great deal of Fixing crosslink sites, sulfur/porous carbon composite is fixed in " half cage " formed by Graphene.
Described graphene coated sulfur/porous carbon composite is that the hydrogel post of graphene coated sulfur/porous carbon composite exists The composite formed after removing moisture drying, inherits the graphite of the hydrogel post of graphene coated sulfur/porous carbon composite The three-dimensional cross-linked clad structure of alkene, at the outer surface uniform coated graphite alkene lamella of sulfur/porous carbon composite granule, and at graphite Three-dimensional cross-linked graphene conductive network is formed between the sulfur/porous carbon composite granule of alkene cladding；The sulfur of this graphene coated/ Porous carbon composite possesses classification nucleocapsid structure, and sulfur/porous carbon composite is kernel, Graphene be then evenly coated at sulfur/ The outer surface of porous carbon composite granule becomes the protection shell of " half cage " shape, makes product such as many sulfurations in discharge process Lithium is limited in " half cage ", it is possible to the effectively loss by dissolution of the suppression electric discharge many lithium sulfides of intermediate product；Wherein, sulfur/porous Carbon composite be sulphur content be dispersed on the surface of porous carbon materials and in hole formed, porous carbon by activated carbon, Graphene, In white carbon black, CNT, templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon a kind of or the most several group Become；In graphene coated sulfur/porous carbon composite, the mass ratio of sulfur, porous carbon and graphene coated layer is 1:(0.02～20): (0.02～20).
It is the most efficient that the hydrothermal preparing process of graphene coated sulfur/porous carbon composite that the present invention provides has technical process Advantage: Graphene slurry that (1) uses or graphene oxide slurry provide can high degree of dispersion steady in a long-term in a solvent Few number of plies graphene sheet layer or graphene oxide lamella, and this slurry can moistening sulfur/porous carbon composite well, Make both reach dispersion and the mixing of high uniformity, be self-assembly of three-dimensional cross-linked Graphene after being then passed through hydrothermal treatment consists many Pore network, uniformly wraps up in the hole of cross-linked graphene network by sulfur/porous carbon composite, and formation graphene coated sulfur/ The hydrogel post of porous carbon composite, can form the Graphene " half cage " to sulfur/porous carbon composite the most after drying Shape is coated with；(2) by control hydrothermal treatment consists temperature and time, can obtain the sulfur by higher reducing degree graphene coated/ Porous carbon composite；(3) hydrothermal preparing process of the present invention is suitable for preparing the Graphene bag of various different sulfur/porous carbon Cover material；(4) preparation method of the present invention does not use toxic raw materials, does not works the mischief environment and personnel health.
Graphene coated sulfur/porous carbon prepared by the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite of the present invention Composite have uniqueness classification nucleocapsid structure, when being used as the positive active material of lithium-sulfur cell, compared with the existing technology, Have the advantage that
Compared with graphene coated bright sulfur particulate composite, the graphene coated sulfur of the present invention/porous carbon composite continuity Original advantage of internal sulfur/porous carbon composite, the porous carbon such as high-specific surface area, high porous volume can accommodate substantial amounts of simple substance Sulfur, it is ensured that sulfur high-load in the composite；Sulfur being uniformly distributed in porous carbon improves the active substance of sulfur and utilizes Rate；The physics confinement effect of porous carbon can slow down the loss by dissolution of many lithium sulfides intermediate product.On this basis, with other side Graphene coated material prepared by method is compared, and sulfur/porous carbon composite particle exterior surface can more uniformly be coated with high conductivity Few number of plies graphene sheet layer, form intergranular three-dimensional cross-linked graphene conductive network, particularly reduce sulfur/porous carbon multiple The contact resistance that on condensation material particle exterior surface, the sulfur of insulating properties causes, connects to single sulfur/porous carbon composite granule The entirety of one conduction, therefore can improve the active material utilization of material, significantly improve high-rate charge-discharge capability； Meanwhile, the graphene coated layer of " half cage " shape can adsorb further, stop many lithium sulfides intermediate product, suppresses it to dissolve stream Lose, play the effect of the second weight barrier, effectively improve the charge-discharge performance of material.Therefore the hydrothermal method of the present invention Graphene coated sulfur/the porous carbon composite of preparation is that one possesses height ratio capacity, long circulation life and good high rate capability Positive electrode, can be used for lithium secondary battery field.
Accompanying drawing explanation
Fig. 1 is the digital photograph of the hydrogel post of the graphene coated sulfur/absorbent charcoal composite material of preparation in test one；
Fig. 2 is the stereoscan photograph (low amplification) of the graphene coated sulfur/absorbent charcoal composite material of preparation in test one；
Fig. 3 is the stereoscan photograph (high-amplification-factor) of the graphene coated sulfur/absorbent charcoal composite material of preparation in test one；
Fig. 4 is the high-resolution-ration transmission electric-lens photo of the graphene coated sulfur/absorbent charcoal composite material of preparation in test one；
Fig. 5 is the graphene coated sulfur/absorbent charcoal composite material of preparation cycle performance curve under different multiplying in test one；
Fig. 6 be in test one the graphene coated sulfur/absorbent charcoal composite material of preparation under different multiplying discharge and recharge electromotive force bent Line；
Fig. 7 is the graphene coated sulfur/absorbent charcoal composite material of preparation cycle performance curve under 1C multiplying power in test one；
Fig. 8 is that the graphene coated sulfur/absorbent charcoal composite material prepared in test one is when circulating for the 1st, 50,100,200 1C multiplying power under discharge and recharge potential curve；
Fig. 9 is the digital photograph of the hydrogel post of the graphene coated sulfur/absorbent charcoal composite material of preparation in test two；
Figure 10 is the graphene coated sulfur/absorbent charcoal composite material of preparation cycle performance curve under different multiplying in test two；
Figure 11 is that in test two, the graphene coated sulfur/absorbent charcoal composite material of preparation discharge and recharge electromotive force under different multiplying is bent Line；
Detailed description of the invention
Technical solution of the present invention is not limited to act detailed description of the invention set forth below, also includes appointing between each detailed description of the invention Meaning combination.
Detailed description of the invention one: the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of present embodiment is pressed Following steps are carried out:
One, Graphene slurry is prepared: described Graphene slurry is made up of Graphene and water, and graphene sheet layer is the most uniform Ground dispersion；Wherein, the water content of this Graphene slurry is 90%～99.99%；
Two, prepare sulfur/porous carbon composite, wherein porous carbon materials by activated carbon, Graphene, white carbon black, CNT, A kind of or the most several composition in templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon, sulfur/porous carbon is combined In material, sulfur is 1:(0.02～20 with the mass ratio of porous carbon)；
Three, be (0.02～20) by the mass ratio of the sulfur in the Graphene in Graphene slurry and sulfur/porous carbon composite: 1, general Sulfur/porous carbon composite prepared by step 2 joins to mix in Graphene slurry prepared by step one and is uniformly dispersed, and then will Mixed slurry adds and has in teflon-lined hydrothermal reaction kettle, by after airtight for reactor at 100～220 DEG C of hydro-thermals Reason 1～24h, obtains hydrogel post, rolls extrusion moisture therein, then the washing that is soaked in water after being taken out by hydrogel post, It is dried 1～24h at a temperature of 20～90 DEG C, is ground into powder, then at 20～90 DEG C, be vacuum dried 1～24h, obtain stone Ink alkene cladding sulfur/porous carbon composite.
It is the most efficient that the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite of present embodiment has technical process Advantage: the Graphene slurry that (1) uses provide can high degree of dispersion few number of plies graphene sheet layer steady in a long-term in a solvent, And this slurry can moistening sulfur/porous carbon composite well, make both reach dispersion and the mixing of high uniformity, then After hydrothermal treatment consists, it is self-assembly of three-dimensional cross-linked Graphene porous network, sulfur/porous carbon composite is uniformly wrapped up In the hole of cross-linked graphene network, form the hydrogel post of graphene coated sulfur/porous carbon composite, the most after drying Graphene can be formed " half cage " shape of sulfur/porous carbon composite is coated with；(2) by control hydrothermal treatment consists temperature and Time, can obtain by the sulfur/porous carbon composite of higher reducing degree graphene coated；(3) hydro-thermal of present embodiment Preparation method is suitable for preparing the graphene coated material of various different sulfur/porous carbon；(4) preparation method of present embodiment Do not use toxic raw materials, environment and personnel health are not worked the mischief.
Detailed description of the invention two: the Graphene slurry in present embodiment step one unlike detailed description of the invention one concrete Preparation method is as follows:
(1) graphite and reducing agent are weighed；Wherein graphite is 1:(0.1～1000 with the mass ratio of reducing agent)；Reducing agent is Vitamin C A kind of or the most several combination in acid, KOH, NaOH, LiOH and ammonia；
(2) graphite oxidation that step (1) weighs is become graphite oxide；
(3) it is 0.01mg mL by the concentration of graphite oxide-1～50mg mL-1, graphite oxide step (2) obtained adds In water, peel off under the ultrasound condition that frequency is 20～100KHz, disperse 0.5～10h, obtain graphene oxide water-dispersible Liquid；
(4) under conditions of temperature is 4 DEG C～100 DEG C, add in the graphene oxide aqueous dispersions that step (3) obtains Reducing agent, under the ultrasound condition that frequency is 20～100KHz, reduction 0.2h～24h, obtains Graphene aqueous dispersions；
(5) the Graphene aqueous dispersions that step (4) obtains is carried out vacuum filtration, or decompression rotary evaporation, or rotation Turn centrifugal treating, form the slurry of thickness, the most again it is carried out dialysis or vacuum filtration washing, obtain Graphene slurry； The water content of this Graphene slurry is 90%～99.99%.
Other is identical with detailed description of the invention one.
The Graphene slurry prepared in the present embodiment be a kind of steady in a long-term, Graphene with few number of plies structure in water high Spending homodisperse slurry, this slurry is made up of Graphene and water.Owing to described Graphene is by the electronation of graphite oxide Method prepare, graphene sheet layer exists a certain amount of electronegative oxygen-containing functional group, these electronegative oxygen-containing functional groups it Between electrostatic repulsion make Graphene keep high degree of dispersion state in water with few number of plies structure, and this slurry can be 3～the homogeneously dispersed state of stable for extended periods of time in 4 months, it is advantageously implemented the Graphene of few number of plies on sulfur/porous carbon surface Uniformly cladding.
Detailed description of the invention three: in present embodiment step (2) unlike detailed description of the invention one or two, graphite oxidation becomes Method for graphite oxide is as follows: adding 120mL mass percentage concentration in dry beaker is the H of 98%2SO4, then Beaker is placed in ice-water bath, adds 5g graphite and 2.5g NaNO3, stir with the speed of 50～500 revs/min, the most gradually Add 15g powder KMnO4, under ice-water bath, stirring condition, continue reaction 2h；Beaker is moved into the constant temperature of 35 ± 1 DEG C Oil bath continues reaction 2h；After being slowly added to 360mL distilled water under the stirring condition that rotating speed is 50～500 revs/min, control Temperature constant processed, in 75 DEG C, continues isothermal reaction 1h；Add the distilled water that 1000mL temperature is 40 DEG C, add 50mL matter Amount percentage concentration is the hydrogen peroxide of 30%, then vacuum filtration；Filter cake is cleaned with the hydrochloric acid that mass percentage concentration is 5%, until Without SO in filtrate4 2-Ion, then use distilled water filtering and washing；Take out filter cake, the air dry oven of 50 DEG C be dried 24h, Obtain graphite oxide.Other is identical with detailed description of the invention one or two.
SO in present embodiment4 2-Ion can use BaCl2Solution detects.
Detailed description of the invention four: the sulfur/porous in present embodiment step 2 unlike one of detailed description of the invention one to three The preparation method of carbon composite is melted diffusion method, specific as follows: sulfur and porous carbon mix homogeneously are placed on inert atmosphere Normal pressure or environment under high pressure under, or be placed under vacuum environment, at 100～400 DEG C, heat 1h～24h, make the melted diffusion of sulfur In the hole of porous carbon and outer surface, obtaining sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).Other is identical with one of detailed description of the invention one to three.
Detailed description of the invention five: the sulfur/porous in present embodiment step 2 unlike one of detailed description of the invention one to three The preparation method of carbon composite is sulfur steam completion method, specific as follows: to be added in inert atmosphere or vacuum environment by elemental sulfur Heat is sublimed into sulfur steam to 100～500 DEG C, and sulfur steam is filled in neighbouring porous carbon, condenses subsequently, obtains sulfur/porous carbon Composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).Other is identical with one of detailed description of the invention one to three.
Detailed description of the invention six: the sulfur/porous in present embodiment step 2 unlike one of detailed description of the invention one to three The preparation method of carbon composite is sulphur-containing solution infusion process: sulfur is dissolved in Carbon bisulfide, benzene, toluene, dimethyl sulfoxide, In the solvent of a kind of or the most several composition in carbon tetrachloride, ether, chloroform, form sulphur-containing solution, porous carbon is added Sulphur-containing solution impregnates, is subsequently dried removal solvent, make sulfur deposit in the hole of porous carbon and on outer surface, obtain sulfur/many Hole carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).One of other and detailed description of the invention one to three Identical.
Detailed description of the invention seven: the sulfur/porous in present embodiment step 2 unlike one of detailed description of the invention one to three The preparation method of carbon composite is chemical reaction method, will join in the aqueous solution of thiosulfate or sulfide by porous carbon Dispersion mixing is uniform, makes thiosulfate or sulfide be impregnated into the pore interior of porous carbon, adds dilute acid soln, make sulfur generation Sulfate or sulfide generation chemical reaction, elemental sulfur in porous carbon hole and in outside deposition, obtain sulfur/porous carbon multiple Condensation material, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).Other is identical with one of detailed description of the invention one to three.
Detailed description of the invention eight: at the hydro-thermal in present embodiment step 3 unlike one of detailed description of the invention one to seven Reason condition is in 120～200 DEG C of hydrothermal treatment consists 5～18h.Other is identical with one of detailed description of the invention one to seven.
Detailed description of the invention nine: at the hydro-thermal in present embodiment step 3 unlike one of detailed description of the invention one to seven Reason condition is in 140～180 DEG C of hydrothermal treatment consists 8～14h.Other is identical with one of detailed description of the invention one to seven.
Detailed description of the invention ten: the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of present embodiment is pressed Following steps are carried out:
One, graphene oxide slurry is prepared: described graphene oxide slurry is made up of graphene oxide, water and ethanol, oxidation Graphene sheet layer is uniformly dispersed in graphene oxide slurry；Wherein, the containing of graphene oxide in this graphene oxide slurry Amount is 0.01mg mL-1～100mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.001mL mL-1～0.1mL mL-1；
Two, prepare sulfur/porous carbon composite, wherein porous carbon materials by activated carbon, Graphene, white carbon black, CNT, A kind of or the most several composition in templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon, sulfur/porous carbon is combined In material, sulfur is 1:(0.02～20 with the mass ratio of porous carbon)；
Three, by the mass ratio of the graphene oxide in graphene oxide slurry with the sulfur in sulfur/porous carbon composite it is (0.04～40): 1, sulfur/porous carbon composite step 2 prepared joins in graphene oxide slurry prepared by step one mixed Conjunction is uniformly dispersed, and is then added by mixed slurry and has in teflon-lined hydrothermal reaction kettle, after airtight for reactor In 100～220 DEG C of hydrothermal treatment consists 1～24h, obtain hydrogel post, after being taken out by hydrogel post, roll extrusion moisture therein, Be soaked in water washing, is dried 1～24h, is ground into powder, then vacuum is done at 20～90 DEG C at a temperature of 20～90 DEG C Dry 1～24h, obtain graphene coated sulfur/porous carbon composite.
It is the most efficient that the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite of present embodiment has technical process Advantage: the graphene oxide slurry that (1) uses provides and high degree of dispersion few number of plies steady in a long-term can aoxidize stone in a solvent Ink alkene lamella, and this slurry can moistening sulfur/porous carbon composite well, make both reach high uniformity dispersion and Mixing, is self-assembly of three-dimensional cross-linked Graphene porous network, by sulfur/porous carbon composite after being then passed through hydrothermal treatment consists Uniformly wrap up in the hole of cross-linked graphene network, form the hydrogel post of graphene coated sulfur/porous carbon composite, so By Graphene can be formed after drying, " half cage " shape of sulfur/porous carbon composite is coated with；(2) by controlling at hydro-thermal The temperature and time of reason, can obtain by the sulfur/porous carbon composite of higher reducing degree graphene coated；(3) this enforcement The hydrothermal preparing process of mode is suitable for preparing the graphene coated material of various different sulfur/porous carbon；(4) present embodiment Preparation method do not use toxic raw materials, environment and personnel health are not worked the mischief.
Detailed description of the invention 11: the graphene oxide slurry in present embodiment step one unlike detailed description of the invention ten Concrete preparation method as follows:
(1) graphite oxidation is become graphite oxide；
(2) graphite oxide that step (1) obtains is added to the water, peel off under the ultrasound condition that frequency is 20～100KHz, Dispersion 0.5～10h, obtains graphene oxide aqueous dispersions；
(3) in the graphene oxide aqueous dispersions that step (1) obtains, add ethanol, be 20～100KHz in frequency Disperse 0.5～10h under ultrasound condition, obtain graphene oxide slurry；Wherein, graphene oxide in this graphene oxide slurry Content be 0.01mg mL-1～100mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.001mL mL-1~ 0.1mL mL-1。
Other is identical with detailed description of the invention ten.
Graphene oxide slurry prepared by present embodiment be a kind of steady in a long-term, graphene oxide with few number of plies structure molten The homodisperse slurry of agent camber, this slurry is made up of graphene oxide, water and ethanol.Due on graphene oxide lamella The electrostatic repulsion existed between the most electronegative oxygen-containing functional group, these electronegative oxygen-containing functional groups makes oxygen Functionalized graphene keeps high degree of dispersion state in a solvent with few number of plies structure, and this slurry can be protected in 3～4 months for a long time Keep steady fixed homogeneously dispersed state, is advantageously implemented the Graphene uniform cladding on sulfur/porous carbon surface of few number of plies.Wherein, In this graphene oxide slurry, the content of graphene oxide is 0.01mg mL-1～100mg mL-1, in this graphene oxide slurry The content of ethanol is 0.001mL mL-1～0.1mL mL-1。
Detailed description of the invention 12: graphite oxygen in present embodiment step (1) unlike detailed description of the invention ten or 11 Chemical conversion is as follows for the method for graphite oxide: adding 120mL mass percentage concentration in dry beaker is the H of 98%2SO4, Then beaker is placed in ice-water bath, adds 5g graphite and 2.5g NaNO3, stir with the speed of 50～500 revs/min, simultaneously It is gradually added into 15g powder KMnO4, under ice-water bath, stirring condition, continue reaction 2h；Beaker is moved into 35 ± 1 DEG C Thermostatical oil bath relaying continuous reaction 2h；After being slowly added to 360mL distilled water under the stirring condition that rotating speed is 50～500 revs/min, Control temperature constant, in 75 DEG C, continues isothermal reaction 1h；Add the distilled water that 1000mL temperature is 40 DEG C, add 50mL Mass percentage concentration is the hydrogen peroxide of 30%, then vacuum filtration；Filter cake is cleaned, directly with the hydrochloric acid that mass percentage concentration is 5% Without SO to filtrate4 2-Ion, then use distilled water filtering and washing；Take out filter cake, the air dry oven of 50 DEG C be dried 24h, Obtain graphite oxide.Other is identical with detailed description of the invention ten or 11.
SO in present embodiment4 2-Ion can use BaCl2Solution detects.
Detailed description of the invention 13: the sulfur in present embodiment step 2 unlike one of detailed description of the invention ten to ten two/ The preparation method of porous carbon composite is melted diffusion method, specific as follows: by sulfur and porous carbon mix homogeneously, by mixture It is placed under normal pressure or the environment under high pressure of inert atmosphere, or is placed under vacuum environment, at 100～400 DEG C, heat 1h～24h, Make sulfur melt to be diffused in the hole of porous carbon and outer surface, obtain sulfur/porous carbon composite, wherein sulfur and the matter of porous carbon Amount ratio is 1:(0.02～20).Other is identical with one of detailed description of the invention ten to ten two.
Detailed description of the invention 14: the sulfur in present embodiment step 2 unlike one of detailed description of the invention ten to ten two/ The preparation method of porous carbon composite is sulfur steam completion method, specific as follows: by elemental sulfur in inert atmosphere or vacuum environment In be heated to 100～500 DEG C and be sublimed into sulfur steam, sulfur steam is filled in neighbouring porous carbon, condenses subsequently, obtains sulfur/many Hole carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).Other with detailed description of the invention ten to ten two it One is identical.
Detailed description of the invention 15: the sulfur in present embodiment step 2 unlike one of detailed description of the invention ten to ten two/ The preparation method of porous carbon composite is sulphur-containing solution infusion process: sulfur is dissolved in Carbon bisulfide, benzene, toluene, dimethyl In the solvent of a kind of or the most several composition in sulfoxide, carbon tetrachloride, ether, chloroform, form sulphur-containing solution, by porous Carbon adds dipping in sulphur-containing solution, is subsequently dried removal solvent, makes sulfur deposit in the hole of porous carbon and on outer surface, To sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).Other with detailed description of the invention ten to One of 12 identical.
Detailed description of the invention 16: the sulfur in present embodiment step 2 unlike one of detailed description of the invention ten to ten two/ The preparation method of porous carbon composite is chemical reaction method, will join the water-soluble of thiosulfate or sulfide by porous carbon In liquid, dispersion mixing is uniform, makes thiosulfate or sulfide be impregnated into the pore interior of porous carbon, adds dilute acid soln, make Thiosulfate or sulfide generation chemical reaction, elemental sulfur in porous carbon hole and in outside deposition, obtain sulfur/porous Carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).One of other and detailed description of the invention ten to ten two Identical.
Detailed description of the invention 17: the water in present embodiment step 3 unlike one of detailed description of the invention ten to ten six Heat treatment condition is in 120～200 DEG C of hydrothermal treatment consists 5～18h.Other is identical with one of detailed description of the invention ten to ten six.
Detailed description of the invention 18: the water in present embodiment step 3 unlike one of detailed description of the invention ten to ten six Heat treatment condition is in 140～180 DEG C of hydrothermal treatment consists 8～14h.Other is identical with one of detailed description of the invention ten to ten six.
By following verification experimental verification beneficial effects of the present invention:
Test one: the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of this test one enters according to the following steps OK:
One, Graphene slurry is prepared.The water content of this Graphene slurry is 96.5%；
Two, preparing sulfur/absorbent charcoal composite material, wherein the mass ratio of sulfur and activated carbon is 3:2；
Three, it is 0.556:1 by the mass ratio of the sulfur in the Graphene in Graphene slurry and sulfur/absorbent charcoal composite material, by step Sulfur/the absorbent charcoal composite material of two preparations joins to mix in Graphene slurry prepared by step one and is uniformly dispersed, and is mixed by gained Slurry is placed in be had in teflon-lined hydrothermal reaction kettle, by after airtight for reactor 180 DEG C of hydrothermal treatment consists 13.3h, Graphene in mixed slurry lower is reduced further hydrothermal, and meanwhile, the mixed slurry in hydrothermal reaction kettle changes Become the water of clarification and the hydrogel post of the cylindrical graphene coated sulfur/absorbent charcoal composite material of the centre that is in water, by hydrogel Post rolls extrusion moisture therein after taking out, be repeatedly soaked in water its washes clean, and at 60 DEG C, forced air drying 10h, grinds Grinds powder, then at 60 DEG C, it is vacuum dried 10h, obtain graphene coated sulfur/absorbent charcoal composite material.
Wherein, in step one, the preparation method of Graphene slurry sequentially includes the following steps:
(1) 1g graphite and 16g KOH are weighed；
(2) graphite oxidation that step (1) weighs is become graphite oxide.Concrete operations are: add in dry beaker 24mL mass percentage concentration is the H of 98%2SO4, then it is placed in ice-water bath, adds 1g graphite and 0.5g NaNO3, Stir with the speed of 100 revs/min, be gradually added into 3g powder KMnO simultaneously4, continue anti-under ice-water bath, stirring condition Answer 2h；Beaker is moved into the thermostatical oil bath relaying continuous reaction 2h of 35 ± 1 DEG C；Under the stirring condition that rotating speed is 100 revs/min After being slowly added to 72mL distilled water, control temperature constant, in 75 DEG C, continues isothermal reaction 1h；Adding 200mL temperature is The distilled water of 40 DEG C, adding 10mL mass percentage concentration is the hydrogen peroxide of 30%, then vacuum filtration；By appropriate quality hundred Point concentration be 5% hydrochloric acid clean filter cake, until without SO in filtrate4 2-Ion (uses BaCl2Solution detects), then take out with distilled water Filter washing；Take out filter cake, the air dry oven of 50 DEG C is dried 24h, obtains graphite oxide；
(3) it is 1mg mL by the concentration of graphite oxide-1, the graphite oxide that step (2) obtains is added to the water, in frequency For stripping ultrasonic under conditions of 40KHz, dispersion 1h, obtain graphene oxide aqueous dispersions；
(4) under conditions of temperature is 80 DEG C, in the graphene oxide aqueous dispersions that step (3) obtains, step (1) is added The KOH weighed, under the ultrasound condition that frequency is 40KHz, reduction 3h, obtains Graphene aqueous dispersions；
(5) the Graphene aqueous dispersions that step (4) obtains is joined in the flask of Rotary Evaporators, in vacuum be -0.09MPa, temperature are 75 DEG C, rotating speed reduces pressure under conditions of being 60 revs/min rotary evaporation to the slurry of thickness from Graphene Aqueous dispersions separates out, then will be attached to load, after the slurry of the Graphene on flask inwall scrapes, the molecular weight that dams and be In the dialysis bag of 8000～14000, then dialysis bag is immersed in dialysis 120h in distilled water, obtains steady in a long-term, Graphene Lamella is at water camber scattered Graphene slurry.The water content of this Graphene slurry is 96.5%.
In step 2, the preparation method of sulfur/absorbent charcoal composite material is melted diffusion method: by sulfur that mass ratio is 3:2 and activated carbon Adding in the ball grinder of planetary ball mill, the toluene of 5 times of sulfur quality of addition is as ball milling dispersant, at 200 revs/min Under conditions of ball milling mixing 7h, mixture is vacuum dried at 60 DEG C 12h remove toluene, be subsequently placed in full Ar gas In politef hermetic container, at 155 DEG C, heat 18h, make sulfur melt and be diffused in the hole of activated carbon and outer surface, Obtaining sulfur/absorbent charcoal composite material, wherein the mass ratio of sulfur and activated carbon is 3:2, and the weight/mass percentage composition of sulfur is 60%.
In step 3, the hydrogel post of described graphene coated sulfur/absorbent charcoal composite material is by hydro-thermal self-generated pressure and height The three-dimensional cross-linked Graphene porous network that is self-assembly of under the conditions of temperature, the sulfur/activated carbon being wrapped in Graphene porous network are multiple Condensation material, and the large quantity of moisture composition being distributed in porous network；This hydrogel post is all solids in mixed slurry The cylinder being self-assembly of after matter and a certain amount of moisture hydrothermal treatment, separates out after hydrothermal treatment consists from mixed slurry, and Mixed slurry only leaves in addition to this hydrogel post the water of clarification；Due to hydro-thermal self assembly effect, graphene coated sulfur/work In the hydrogel post of property carbon composite, various materials distribute very evenly, Graphene three-dimensional cross-linked formation micro/nano level porous web Network, is uniformly coated with sulfur/absorbent charcoal composite material wherein, wherein fills large quantity of moisture simultaneously, additionally at hydro-thermal self-generated pressure and Under hot conditions, the big π bond energy that is conjugated of graphenic surface reaches and the conjugation of activated carbon graphite microcrystal in sulfur/absorbent charcoal composite material π key-like becomes π-π adelphotaxy, makes sulfur/set up a considerable amount of fixing crosslinking position between absorbent charcoal composite material and Graphene Point, sulfur/absorbent charcoal composite material is fixed in " half cage " formed by Graphene.
Graphene coated sulfur/absorbent charcoal composite material prepared by the hydrothermal method of this test one is that graphene coated sulfur/activated carbon is multiple The composite that the hydrogel post of condensation material is formed after removing moisture drying, inherits graphene coated sulfur/activated carbon composite wood The three-dimensional cross-linked clad structure of Graphene of the hydrogel post of material, the outer surface at sulfur/absorbent charcoal composite material granule is uniformly coated with stone Ink alkene lamella, and between the sulfur/absorbent charcoal composite material granule of graphene coated, form three-dimensional cross-linked graphene conductive network； Sulfur/the absorbent charcoal composite material of this graphene coated possesses classification nucleocapsid structure, and sulfur/absorbent charcoal composite material is kernel, graphite Alkene is then evenly coated at the outer surface of sulfur/absorbent charcoal composite material granule becomes the protection shell of " half cage " shape, makes discharge process In product be limited in " half cage " such as many lithium sulfides, it is possible to the effectively dissolving stream of the suppression electric discharge many lithium sulfides of intermediate product Lose；In the mensuration of elemental analyser, graphene coated sulfur/absorbent charcoal composite material, the weight/mass percentage composition of sulfur is 43.764%.
Taking pictures the hydrogel post of obtained graphene coated sulfur/absorbent charcoal composite material, obtained digital photograph is such as Shown in Fig. 1.Three-dimensional cross-linked graphite is comprised it can be seen that can be prepared by the hydrothermal method in this test one Alkene porous network, the sulfur/absorbent charcoal composite material being wrapped in Graphene porous network, and be distributed in porous network big The hydrogel post of amount moisture.
Obtained graphene coated sulfur/absorbent charcoal composite material is scanned ultramicroscope (SEM) observe, such as Fig. 2 Shown in 3.From Fig. 2 and 3 it can be seen that sulfur/absorbent charcoal composite material is irregular grain shape, Graphene then table Being now obvious lamellar structure, the graphene coated of sheet forms " half cage " on granular sulfur/absorbent charcoal composite material surface Shape protection shell, and each independent sulfur/absorbent charcoal composite material granule is connected to a complete network；By obtained Graphene coated sulfur/absorbent charcoal composite material carry out high resolution transmission electron microscopy (TEM) observe, as shown in Figure 4. From fig. 4, it can be seen that composite material granular is wound around by Graphene, the sulfur/absorbent charcoal composite material of cladding forms, composite wood Between the graphene coated layer of material granule, connection constitutes the conductive network of three-dimensional, and this will improve the electronic conductivity of material, " half cage " shape protection shell formed after cladding, it is possible to effectively stop the loss by dissolution of the many lithium sulfides of reaction intermediate.
Using obtained graphene coated sulfur/absorbent charcoal composite material as positive active material, according to active substance, acetylene black, The mass ratio of PTFE is that 80:17:3 is sufficiently mixed, and is vacuum dried 12h, is then washed into straight after being pressed into thin slice at 60 DEG C Footpath is the positive plate (on electrode, the carrying capacity of sulfur is at about 2mg) of 15mm.With lithium paper tinsel as negative pole, with Celgard2400 for every Film, electrolyte uses 1.0mol L-1The 1,2-dimethoxy-ethane (DME) of double (trifluoromethanesulp-onyl-onyl imide) lithium (LiTFSI) and The solution of DOX (DOL) (volume ratio is 1:1), wherein contains 0.25mol L-1Lithium nitrate.Hands at full Ar gas Casing is assembled into CR2025 type button cell.
As the lithium-sulfur cell of positive electrode, constant current charge-discharge test is carried out for graphene coated sulfur/absorbent charcoal composite material, The obtained cycle performance curve under different multiplying is as shown in Figure 5, it can be seen that graphene coated sulfur/activated carbon composite wood Material discharge capacity first under 0.1C multiplying power is up to 1467mAh g-1, reached the 88% of sulfur electrode theoretical capacity.0.2C Discharge capacity is 927mAh g-1, 0.5C discharge capacity is 850mAh g-1, 1C discharge capacity is 793mAh g-1, 2C is put Capacitance is 711mAh g-1, 3C discharge capacity is 630mAh g-1, the high rate capability of illustrative material is the most excellent, and this is same Three-dimensional cross-linked graphene coated structure and the internal package effect of activated carbon improve the close phase of electric conductivity of composite Close；769mAh g is remained within 0.1C multiplying power discharge capacity after 45 circulations-1, and maintain a phase To stable state, capacity attenuation speed is relatively low, and its reason is that the double-coating effect of activated carbon and Graphene effectively suppresses The loss by dissolution of electric discharge intermediate product many lithium sulfides.
Fig. 6 be graphene coated sulfur/absorbent charcoal composite material as positive electrode lithium-sulfur cell 0.1C, 0.2C, 0.5C, Discharge and recharge potential curve under 1C, 2C and 3C multiplying power, it can be seen that even if yet suffering from two under the conditions of up to 3C multiplying power Individual obvious charge and discharge platform, correspond to the different discharge and recharge stages respectively, and the discharge plateaus under 3C multiplying power is still up to 1.9V, and the distance between charge and discharge platform is the least, illustrates that electrode polarization is the least, and reactivity is the highest.This same composite wood The activated carbon of material, Graphene double-coating nucleocapsid structure are closely related.
Fig. 7 is the graphene coated sulfur/absorbent charcoal composite material lithium-sulfur cell as positive electrode cyclicity under 1C multiplying power Energy curve, the activation under 2 0.25C multiplying powers, the discharge capacity first under 1C multiplying power reaches 942mAh g-1, such as figure Visible, in 200 cyclic processes, capacity attenuation speed is relatively slow, and progressively reaches a relatively stable cycle stage, 634mAh g is remained within to discharge capacity during the 200th circulation-1, show good cyclical stability.This circulation Stability is mainly derived from the dual cladding of activated carbon and Graphene, effectively slow down the dissolving of the electric discharge many lithium sulfides of intermediate product Migrate.
Fig. 8 is that the graphene coated sulfur/absorbent charcoal composite material lithium-sulfur cell as positive electrode is the 1st, 50,100,200 The discharge and recharge potential curve under 1C multiplying power during individual circulation, it can be seen that remain two charge and discharge platform clearly, fill Distance between discharge platform is the least, and the polarization of illustrative material is the least, and this provides all with the classification nucleocapsid structure of material Even three-dimensional conductive network is relevant.
The above experimental result all shows, few number of plies graphite of sulfur/absorbent charcoal composite material particle exterior surface cladding high conductivity Alkene lamella, defines intergranular conductive network, particularly reduces insulating properties on sulfur/absorbent charcoal composite material particle exterior surface The contact resistance that causes of sulfur, improve active material utilization and the high rate capability of material the most very significantly；Meanwhile, " half cage " shape graphene coated layer can adsorb further, stop many lithium sulfides intermediate product, suppresses its loss by dissolution, rises To the effect of the second weight barrier, effectively improve the charge-discharge performance of material.
The preparation method of the graphene coated sulfur/absorbent charcoal composite material of this test one has a simply efficient advantage of technical process: (1) the Graphene slurry used provides and at the dispersion of water camber few number of plies graphene sheet layer steady in a long-term, and can be somebody's turn to do Slurry can moistening sulfur/porous carbon composite well, make both reach dispersion and the mixing of high uniformity, be then passed through water It is self-assembly of three-dimensional cross-linked Graphene porous network after heat treatment, sulfur/porous carbon composite is uniformly wrapped up crosslinking stone In the hole of ink alkene network, form the hydrogel post of graphene coated sulfur/porous carbon composite, get final product shape the most after drying Become Graphene that " half cage " shape of sulfur/porous carbon composite is coated with；(2) by controlling the temperature and time of hydrothermal treatment consists, Can obtain by the sulfur/absorbent charcoal composite material of higher reducing degree graphene coated；(3) preparation method of this test one does not makes With toxic raw materials, environment and personnel health are not worked the mischief.
Test two: the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of this test two enters according to the following steps OK:
One, graphene oxide slurry is prepared.In this graphene oxide slurry, the content of graphene oxide is 5mg mL-1, this oxygen In functionalized graphene slurry, the content of ethanol is 0.0375mL mL-1；
Two, preparing sulfur/absorbent charcoal composite material, wherein the mass ratio of sulfur and activated carbon is 3:2；
Three, it is 1.111:1 by the mass ratio of the sulfur in the graphene oxide in graphene oxide slurry and sulfur/absorbent charcoal composite material, Sulfur/absorbent charcoal composite material step 2 prepared joins to mix in graphene oxide slurry prepared by step one and is uniformly dispersed, Being placed in by gained mixed slurry has in teflon-lined hydrothermal reaction kettle, by after airtight for reactor at 180 DEG C of hydro-thermals Reason 13.3h, the graphene oxide in mixed slurry is reduced into Graphene under hydrothermal, meanwhile, in hydrothermal reaction kettle Mixed slurry is transformed into the water of clarification and the hydrogel of the cylindrical graphene coated sulfur/absorbent charcoal composite material of the centre that is in water Post, rolls extrusion moisture therein, is repeatedly soaked in water its washes clean, air blast at 60 DEG C after being taken out by hydrogel post It is dried 10h, is ground into powder, then at 60 DEG C, be vacuum dried 10h, obtain graphene coated sulfur/absorbent charcoal composite material.
Wherein, in step one, the preparation method of graphene oxide slurry sequentially includes the following steps:
(1) 1g graphite oxidation is become graphite oxide.Concrete operations are: add 24mL percent mass in dry beaker Concentration is the H of 98%2SO4, then it is placed in ice-water bath, adds 1g graphite and 0.5g NaNO3, with 100 revs/min Speed stirring, be gradually added into 3g powder KMnO simultaneously4, under ice-water bath, stirring condition, continue reaction 2h；To burn Cup moves into the thermostatical oil bath relaying continuous reaction 2h of 35 ± 1 DEG C；It is slowly added to 72mL under the stirring condition that rotating speed is 100 revs/min After distilled water, control temperature constant, in 75 DEG C, continues isothermal reaction 1h；Add the distilled water that 200mL temperature is 40 DEG C, Adding 10mL mass percentage concentration is the hydrogen peroxide of 30%, then vacuum filtration；It is the salt of 5% by appropriate mass percentage concentration Filter cake is cleaned in acid, until without SO in filtrate4 2-Ion (uses BaCl2Solution detects), then use distilled water filtering and washing；Take out filter Cake, is dried 24h in the air dry oven of 50 DEG C, obtains graphite oxide；
(2) graphite oxide that step (1) obtains is added to the water, peels off under the ultrasound condition that frequency is 40KHz, divide Dissipate 1h, obtain graphene oxide aqueous dispersions；
(3) in the graphene oxide aqueous dispersions that step (1) obtains, add a certain amount of ethanol, be 40KHz in frequency Ultrasound condition under disperse 1h, obtain graphene oxide slurry；Wherein, the containing of graphene oxide in this graphene oxide slurry Amount is 5mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.0375mL mL-1。
In step 2, the preparation method of sulfur/absorbent charcoal composite material is melted diffusion method: by sulfur that mass ratio is 3:2 and activated carbon Adding in the ball grinder of planetary ball mill, the toluene of 5 times of sulfur quality of addition is as ball milling dispersant, at 200 revs/min Under conditions of ball milling mixing 7h, mixture is vacuum dried at 60 DEG C 12h remove toluene, be subsequently placed in full Ar gas In politef hermetic container, at 155 DEG C, heat 18h, make sulfur melt and be diffused in the hole of activated carbon and outer surface, Obtaining sulfur/absorbent charcoal composite material, wherein the mass ratio of sulfur and activated carbon is 3:2, and the weight/mass percentage composition of sulfur is 60%.
In step 3, the hydrogel post of described graphene coated sulfur/absorbent charcoal composite material is by hydro-thermal self-generated pressure and height The three-dimensional cross-linked Graphene porous network that is self-assembly of under the conditions of temperature, the sulfur/activated carbon being wrapped in Graphene porous network are multiple Condensation material, and the large quantity of moisture composition being distributed in porous network；This hydrogel post is all solids in mixed slurry The cylinder being self-assembly of after matter and a certain amount of moisture hydrothermal treatment, separates out after hydrothermal treatment consists from mixed slurry, and Mixed slurry only leaves in addition to this hydrogel post the water of clarification；Due to hydro-thermal self assembly effect, graphene coated sulfur/work In the hydrogel post of property carbon composite, various materials distribute very evenly, Graphene three-dimensional cross-linked formation micro/nano level porous web Network, is uniformly coated with sulfur/absorbent charcoal composite material wherein, wherein fills large quantity of moisture simultaneously, additionally at hydro-thermal self-generated pressure and Under hot conditions, the big π bond energy that is conjugated of graphenic surface reaches and the conjugation of activated carbon graphite microcrystal in sulfur/absorbent charcoal composite material π key-like becomes π-π adelphotaxy, makes sulfur/set up a considerable amount of fixing crosslinking position between absorbent charcoal composite material and Graphene Point, sulfur/absorbent charcoal composite material is fixed in " half cage " formed by Graphene.
Graphene coated sulfur/absorbent charcoal composite material prepared by the hydrothermal method of this test two is that graphene coated sulfur/activated carbon is multiple The composite that the hydrogel post of condensation material is formed after removing moisture drying, inherits graphene coated sulfur/activated carbon composite wood The three-dimensional cross-linked clad structure of Graphene of the hydrogel post of material, at the outer surface coated graphite alkene of sulfur/absorbent charcoal composite material granule Lamella, and between the sulfur/absorbent charcoal composite material granule of graphene coated, form three-dimensional cross-linked graphene conductive network；Should Sulfur/the absorbent charcoal composite material of graphene coated possesses classification nucleocapsid structure, and sulfur/absorbent charcoal composite material is kernel, Graphene The outer surface being then evenly coated at sulfur/absorbent charcoal composite material granule becomes the protection shell of " half cage " shape, makes in discharge process Product be limited in " half cage " such as many lithium sulfides, it is possible to the effectively loss by dissolution of the suppression electric discharge many lithium sulfides of intermediate product； In the mensuration of elemental analyser, graphene coated sulfur/absorbent charcoal composite material, the weight/mass percentage composition of sulfur is 44.140%.
Taking pictures the hydrogel post of obtained graphene coated sulfur/absorbent charcoal composite material, obtained digital photograph is such as Shown in Fig. 9.Three-dimensional cross-linked graphite is comprised it can be seen that can be prepared by the hydrothermal method in this test two Alkene porous network, the sulfur/absorbent charcoal composite material being wrapped in Graphene porous network, and be distributed in porous network big The hydrogel post of amount moisture.
Using obtained graphene coated sulfur/absorbent charcoal composite material as positive active material, according to active substance, acetylene black, The mass ratio of PTFE is that 80:17:3 is sufficiently mixed, and is vacuum dried 12h, is then washed into straight after being pressed into thin slice at 60 DEG C Footpath is the positive plate (on electrode, the carrying capacity of sulfur is at about 2mg) of 15mm.With lithium paper tinsel as negative pole, with Celgard2400 for every Film, electrolyte uses 1.0mol L-1The 1,2-dimethoxy-ethane (DME) of double (trifluoromethanesulp-onyl-onyl imide) lithium (LiTFSI) and The solution of DOX (DOL) (volume ratio is 1:1), wherein contains 0.25mol L-1Lithium nitrate.Hands at full Ar gas Casing is assembled into CR2025 type button cell.
As the lithium-sulfur cell of positive electrode, constant current charge-discharge test is carried out for graphene coated sulfur/absorbent charcoal composite material, The obtained cycle performance curve under different multiplying is as shown in Figure 10, it can be seen that graphene coated sulfur/activated carbon composite wood Material discharge capacity first under 0.1C multiplying power is up to 1571mAh g-1, reached the 94% of sulfur electrode theoretical capacity.0.2C Discharge capacity is 1035mAh g-1, 0.5C discharge capacity is 932mAh g-1, 1C discharge capacity is 805mAh g-1, 2C is put Capacitance is 673mAh g-1, 3C discharge capacity is 527mAh g-1, the high rate capability of illustrative material is the most excellent, and this is same Three-dimensional cross-linked graphene coated structure and the internal package effect of activated carbon improve the close phase of electric conductivity of composite Close；899mAh g is remained within 0.1C multiplying power discharge capacity after 53 circulations-1, and maintain a phase To stable state, capacity attenuation speed is relatively low, and its reason is that the double-coating effect of activated carbon and Graphene effectively suppresses The loss by dissolution of electric discharge intermediate product many lithium sulfides.
Figure 11 be graphene coated sulfur/absorbent charcoal composite material as positive electrode lithium-sulfur cell 0.1C, 0.2C, 0.5C, Discharge and recharge potential curve under 1C, 2C and 3C multiplying power, it can be seen that even if yet suffering from two under the conditions of up to 3C multiplying power Individual obvious charge and discharge platform, correspond to the different discharge and recharge stages respectively, and the discharge plateaus under 3C multiplying power is still up to 1.82V, and the distance between charge and discharge platform is the least, illustrates that electrode polarization is the least, and reactivity is the highest.This same composite wood The activated carbon of material, Graphene double-coating nucleocapsid structure are closely related.
The above experimental result all shows, sulfur/absorbent charcoal composite material particle exterior surface is coated with few layer of high conductivity equably Number graphene sheet layer, defines intergranular conductive network, particularly reduces on sulfur/absorbent charcoal composite material particle exterior surface The contact resistance that the sulfur of insulating properties causes, improves active material utilization and the high rate capability of material the most very significantly； Meanwhile, " half cage " shape graphene coated layer can adsorb further, stop many lithium sulfides intermediate product, suppresses its loss by dissolution, Play the effect of the second weight barrier, effectively improve the charge-discharge performance of material.
The preparation method of the graphene coated sulfur/absorbent charcoal composite material of this test two has a simply efficient advantage of technical process: (1) the graphene oxide slurry used provides can high degree of dispersion few number of plies graphene oxide sheet steady in a long-term in a solvent Layer, and this slurry can moistening sulfur/porous carbon composite well, make both reach dispersion and the mixing of high uniformity, It is self-assembly of three-dimensional cross-linked Graphene porous network after being then passed through hydrothermal treatment consists, sulfur/porous carbon composite is uniformly wrapped Wrap up in the hole of cross-linked graphene network, form the hydrogel post of graphene coated sulfur/porous carbon composite, then through dry Graphene can be formed after dry " half cage " shape of sulfur/porous carbon composite is coated with；(2) by controlling the temperature of hydrothermal treatment consists Degree and time, can obtain by the sulfur/absorbent charcoal composite material of higher reducing degree graphene coated；(3) system of this test two Preparation Method does not use toxic raw materials, does not works the mischief environment and personnel health.
Test three: the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of this test three enters according to the following steps OK:
One, Graphene slurry is prepared.The water content of this Graphene slurry is 96.5%；
Two, preparing sulfur/acetylene black composite, wherein the mass ratio of sulfur and acetylene black is 3:2；
Three, it is 0.556:1 by the mass ratio of the sulfur in the Graphene in Graphene slurry and sulfur/acetylene black composite, by step Sulfur/acetylene black the composite of two preparations joins to mix in Graphene slurry prepared by step one and is uniformly dispersed, and is mixed by gained Slurry is placed in be had in teflon-lined hydrothermal reaction kettle, by after airtight for reactor 180 DEG C of hydrothermal treatment consists 13.3h, Graphene in mixed slurry lower is reduced further hydrothermal, and meanwhile, the mixed slurry in hydrothermal reaction kettle changes Become the water of clarification and the hydrogel post of the cylindrical graphene coated sulfur/acetylene black composite of the centre that is in water, by hydrogel Post rolls extrusion moisture therein after taking out, be repeatedly soaked in water its washes clean, and at 60 DEG C, forced air drying 10h, grinds Grinds powder, then at 60 DEG C, it is vacuum dried 10h, obtain graphene coated sulfur/acetylene black composite.
Wherein, in step one, the preparation method of Graphene slurry sequentially includes the following steps:
(1) 1g graphite and 16g KOH are weighed；
(2) graphite oxidation that step (1) weighs is become graphite oxide.Concrete operations are: add in dry beaker 24mL mass percentage concentration is the H of 98%2SO4, then it is placed in ice-water bath, adds 1g graphite and 0.5g NaNO3, Stir with the speed of 100 revs/min, be gradually added into 3g powder KMnO simultaneously4, continue anti-under ice-water bath, stirring condition Answer 2h；Beaker is moved into the thermostatical oil bath relaying continuous reaction 2h of 35 ± 1 DEG C；Under the stirring condition that rotating speed is 100 revs/min After being slowly added to 72mL distilled water, control temperature constant, in 75 DEG C, continues isothermal reaction 1h；Adding 200mL temperature is The distilled water of 40 DEG C, adding 10mL mass percentage concentration is the hydrogen peroxide of 30%, then vacuum filtration；By appropriate quality hundred Point concentration be 5% hydrochloric acid clean filter cake, until without SO in filtrate4 2-Ion (uses BaCl2Solution detects), then take out with distilled water Filter washing；Take out filter cake, the air dry oven of 50 DEG C is dried 24h, obtains graphite oxide；
(3) it is 1mg mL by the concentration of graphite oxide-1, the graphite oxide that step (2) obtains is added to the water, in frequency For stripping ultrasonic under conditions of 40KHz, dispersion 1h, obtain graphene oxide aqueous dispersions；
(4) under conditions of temperature is 80 DEG C, in the graphene oxide aqueous dispersions that step (3) obtains, step (1) is added The KOH weighed, under the ultrasound condition that frequency is 40KHz, reduction 3h, obtains Graphene aqueous dispersions；
(5) the Graphene aqueous dispersions that step (4) obtains is joined in the flask of Rotary Evaporators, in vacuum be -0.09MPa, temperature are 75 DEG C, rotating speed reduces pressure under conditions of being 60 revs/min rotary evaporation to the slurry of thickness from Graphene Aqueous dispersions separates out, then will be attached to load, after the slurry of the Graphene on flask inwall scrapes, the molecular weight that dams and be In the dialysis bag of 8000～14000, then dialysis bag is immersed in dialysis 120h in distilled water, obtains steady in a long-term, Graphene Lamella is at water camber scattered Graphene slurry.The water content of this Graphene slurry is 96.5%.
In step 2, the preparation method of sulfur/acetylene black composite is sulphur-containing solution infusion process: 1.2g sulfur is joined 20mL bis- In nitric sulfid, stirring is to being completely dissolved；0.8g acetylene black is joined stirring 12h in the Carbon bisulfide solution of sulfur, until two Nitric sulfid volatilizees completely, makes sulfur deposit on the surface of acetylene black, obtains sulfur/acetylene black composite, wherein sulfur and acetylene black Mass ratio be 3:2, the weight/mass percentage composition of sulfur is 60%.
In step 3, the hydrogel post of described graphene coated sulfur/acetylene black composite is by hydro-thermal self-generated pressure and height The three-dimensional cross-linked Graphene porous network that is self-assembly of under the conditions of temperature, the sulfur/acetylene black being wrapped in Graphene porous network are multiple Condensation material, and the large quantity of moisture composition being distributed in porous network；This hydrogel post is all solids in mixed slurry The cylinder being self-assembly of after matter and a certain amount of moisture hydrothermal treatment, separates out after hydrothermal treatment consists from mixed slurry, and Mixed slurry only leaves in addition to this hydrogel post the water of clarification；Due to hydro-thermal self assembly effect, graphene coated sulfur/second In the hydrogel post of acetylene black composite, various materials distribute very evenly, Graphene three-dimensional cross-linked formation micro/nano level porous web Network, is uniformly coated with sulfur/acetylene black composite wherein, wherein fills large quantity of moisture simultaneously, additionally at hydro-thermal self-generated pressure and Under hot conditions, the big π bond energy that is conjugated of graphenic surface reaches and the conjugation of acetylene black graphite microcrystal in sulfur/acetylene black composite π key-like becomes π-π adelphotaxy, makes sulfur/set up a considerable amount of fixing crosslinking position between acetylene black composite and Graphene Point, sulfur/acetylene black composite is fixed in " half cage " formed by Graphene.
Graphene coated sulfur/acetylene black composite prepared by the hydrothermal method of this test three is that graphene coated sulfur/acetylene black is multiple The composite that the hydrogel post of condensation material is formed after removing moisture drying, inherits graphene coated sulfur/acetylene black composite wood The three-dimensional cross-linked clad structure of Graphene of the hydrogel post of material, the outer surface at sulfur/acetylene black composite material granular is uniformly coated with stone Ink alkene lamella, and between the sulfur/acetylene black composite material granular of graphene coated, form three-dimensional cross-linked graphene conductive network； The sulfur of this graphene coated/acetylene black composite possesses classification nucleocapsid structure, and sulfur/acetylene black composite is kernel, graphite Alkene is then evenly coated at the outer surface of sulfur/acetylene black composite material granular becomes the protection shell of " half cage " shape, makes discharge process In product be limited in " half cage " such as many lithium sulfides, it is possible to the effectively dissolving stream of the suppression electric discharge many lithium sulfides of intermediate product Lose；In the mensuration of elemental analyser, graphene coated sulfur/acetylene black composite, the weight/mass percentage composition of sulfur is 45.102%.
Using obtained graphene coated sulfur/acetylene black composite as positive active material, according to active substance, acetylene black, The mass ratio of PTFE is that 80:17:3 is sufficiently mixed, and is vacuum dried 12h, is then washed into straight after being pressed into thin slice at 60 DEG C Footpath is the positive plate (on electrode, the carrying capacity of sulfur is at about 2mg) of 15mm.With lithium paper tinsel as negative pole, with Celgard2400 for every Film, electrolyte uses 1.0mol L-1The 1,2-dimethoxy-ethane (DME) of double (trifluoromethanesulp-onyl-onyl imide) lithium (LiTFSI) and The solution of DOX (DOL) (volume ratio is 1:1), wherein contains 0.25mol L-1Lithium nitrate.Hands at full Ar gas Casing is assembled into CR2025 type button cell.
As the lithium-sulfur cell of positive electrode, constant current charge-discharge test is carried out for graphene coated sulfur/acetylene black composite, Graphene coated sulfur/acetylene black composite discharge capacity first under 0.1C multiplying power is up to 1401mAh g-1, reached sulfur The 84% of electrode theoretical capacity.0.2C discharge capacity is 898mAh g-1, 0.5C discharge capacity is 821mAh g-1, 1C is put Capacitance is 757mAh g-1, 2C discharge capacity is 679mAh g-1, 3C discharge capacity is 594mAh g-1, illustrative material High rate capability the most excellent, this with three-dimensional cross-linked graphene coated structure and acetylene black internal package effect improve The electric conductivity of composite is closely related；Remain within 0.1C multiplying power discharge capacity after 48 circulations 741mAh g-1, and maintaining a relatively steady state, capacity attenuation speed is relatively low, and its reason is acetylene black and stone The double-coating effect of ink alkene effectively inhibits the loss by dissolution of the electric discharge many lithium sulfides of intermediate product.
The above experimental result all shows, few number of plies graphite of sulfur/acetylene black composite material granular outer surface cladding high conductivity Alkene lamella, defines intergranular conductive network, particularly reduces insulating properties on sulfur/acetylene black composite material granular outer surface The contact resistance that causes of sulfur, improve active material utilization and the high rate capability of material the most very significantly；Meanwhile, " half cage " shape graphene coated layer can adsorb further, stop many lithium sulfides intermediate product, suppresses its loss by dissolution, rises To the effect of the second weight barrier, effectively improve the charge-discharge performance of material.
The preparation method of the graphene coated sulfur/acetylene black composite of this test three has a simply efficient advantage of technical process: (1) the Graphene slurry used provides and at the dispersion of water camber few number of plies graphene sheet layer steady in a long-term, and can be somebody's turn to do Slurry can moistening sulfur/acetylene black composite well, make both reach dispersion and the mixing of high uniformity, be then passed through water It is self-assembly of three-dimensional cross-linked Graphene porous network after heat treatment, sulfur/acetylene black composite is uniformly wrapped up crosslinking stone In the hole of ink alkene network, form the hydrogel post of graphene coated sulfur/acetylene black composite, get final product shape the most after drying Become Graphene that " half cage " shape of sulfur/acetylene black composite is coated with；(2) by controlling the temperature and time of hydrothermal treatment consists, The sulfur by higher reducing degree graphene coated/acetylene black composite can be obtained；(3) preparation method of this test three does not makes With toxic raw materials, environment and personnel health are not worked the mischief.
Test four: the hydrothermal preparing process of the graphene coated sulfur/porous carbon composite positive pole of this test four enters according to the following steps OK:
One, graphene oxide slurry is prepared.In this graphene oxide slurry, the content of graphene oxide is 5mg mL-1, this oxygen In functionalized graphene slurry, the content of ethanol is 0.0375mL mL-1；
Two, preparing sulfur/multi-wall carbon nano-tube composite material, wherein the mass ratio of sulfur and multi-walled carbon nano-tubes is 7:3；
Three, by the mass ratio of the graphene oxide in graphene oxide slurry with the sulfur in sulfur/multi-wall carbon nano-tube composite material it is 1.111:1, sulfur/multi-wall carbon nano-tube composite material step 2 prepared joins in graphene oxide slurry prepared by step one Mixing is uniformly dispersed, and is placed in by gained mixed slurry and has in teflon-lined hydrothermal reaction kettle, and reactor is airtight After under hydrothermal, be reduced into Graphene in 180 DEG C of hydrothermal treatment consists 13.3h, the graphene oxide in mixed slurry, meanwhile, Cylindrical graphene coated sulfur/many walls carbon of water and the centre that is in water that the mixed slurry in hydrothermal reaction kettle is transformed into clarification is received The hydrogel post of mitron composite, rolls extrusion moisture therein, is repeatedly soaked in water and is washed after being taken out by hydrogel post Washing clean, at 60 DEG C, forced air drying 10h, is ground into powder, then is vacuum dried 10h at 60 DEG C, obtains Graphene Cladding sulfur/multi-wall carbon nano-tube composite material.
Wherein, in step one, the preparation method of graphene oxide slurry sequentially includes the following steps:
(1) 1g graphite oxidation is become graphite oxide.Concrete operations are: add 24mL percent mass in dry beaker Concentration is the H of 98%2SO4, then it is placed in ice-water bath, adds 1g graphite and 0.5g NaNO3, with 100 revs/min Speed stirring, be gradually added into 3g powder KMnO simultaneously4, under ice-water bath, stirring condition, continue reaction 2h；To burn Cup moves into the thermostatical oil bath relaying continuous reaction 2h of 35 ± 1 DEG C；It is slowly added to 72mL under the stirring condition that rotating speed is 100 revs/min After distilled water, control temperature constant, in 75 DEG C, continues isothermal reaction 1h；Add the distilled water that 200mL temperature is 40 DEG C, Adding 10mL mass percentage concentration is the hydrogen peroxide of 30%, then vacuum filtration；It is the salt of 5% by appropriate mass percentage concentration Filter cake is cleaned in acid, until without SO in filtrate4 2-Ion (uses BaCl2Solution detects), then use distilled water filtering and washing；Take out filter Cake, is dried 24h in the air dry oven of 50 DEG C, obtains graphite oxide；
(2) graphite oxide that step (1) obtains is added to the water, peels off under the ultrasound condition that frequency is 40KHz, divide Dissipate 1h, obtain graphene oxide aqueous dispersions；
(3) in the graphene oxide aqueous dispersions that step (1) obtains, add a certain amount of ethanol, be 40KHz in frequency Ultrasound condition under disperse 1h, obtain graphene oxide slurry；Wherein, the containing of graphene oxide in this graphene oxide slurry Amount is 5mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.0375mL mL-1。
In step 2, the preparation method of sulfur/multi-wall carbon nano-tube composite material is chemical reaction method: by 0.12g multi-walled carbon nano-tubes Joining 500mL concentration is 0.045mol L-1Sodium thiosulfate solution in, ultrasonic under conditions of frequency is 40KHz Dispersion 6h, makes multi-walled carbon nano-tubes the most dispersed, and adding 40mL concentration is 1mol L-1HCl solution, make Sodium thiosulfate generation dismutation reaction, elemental sulfur in the deposition of the surface of multi-walled carbon nano-tubes, wash and dry through vacuum filtration After dry, obtaining sulfur/multi-wall carbon nano-tube composite material, wherein the weight/mass percentage composition of sulfur is 70%.
In step 3, the hydrogel post of described graphene coated sulfur/multi-wall carbon nano-tube composite material is by the spontaneous pressure of hydro-thermal The three-dimensional cross-linked Graphene porous network that is self-assembly of under power and hot conditions, the sulfur being wrapped in Graphene porous network/many Wall carbon nano-tube composite material, and the large quantity of moisture composition being distributed in porous network；This hydrogel post is in mixed slurry All solid matters and a certain amount of moisture hydrothermal treatment after the cylinder that is self-assembly of, from mixing slurry after hydrothermal treatment consists Material separates out, and mixed slurry only leaves in addition to this hydrogel post the water of clarification；Due to hydro-thermal self assembly effect, stone In the hydrogel post of ink alkene cladding sulfur/multi-wall carbon nano-tube composite material, various materials distribute very evenly, and Graphene is three-dimensional cross-linked Form micro/nano level porous network, sulfur/multi-wall carbon nano-tube composite material is uniformly coated with wherein, wherein fill a large amount of water simultaneously Point, additionally under hydro-thermal self-generated pressure and hot conditions, the conjugation big π bond energy of graphenic surface reaches and sulfur/multi-walled carbon nano-tubes In composite, the conjugatedπbond of multi-wall carbon nano-tube tube-surface forms π-π adelphotaxy, makes sulfur/multi-walled carbon nano-tubes be combined Setting up a considerable amount of fixing crosslink sites between material and Graphene, sulfur/multi-wall carbon nano-tube composite material is fixed on by stone In " half cage " that ink alkene is formed.
Graphene coated sulfur/multi-wall carbon nano-tube composite material prepared by the hydrothermal method of this test four is graphene coated sulfur/many The composite formed after moisture drying removed by the hydrogel post of wall carbon nano-tube composite material, inherit graphene coated sulfur/ The three-dimensional cross-linked clad structure of Graphene of the hydrogel post of multi-wall carbon nano-tube composite material, at sulfur/multi-walled carbon nano-tubes composite wood The outer surface coated graphite alkene lamella of material granule, and shape between the sulfur/multi-wall carbon nano-tube composite material granule of graphene coated Become three-dimensional cross-linked graphene conductive network；Sulfur/the multi-wall carbon nano-tube composite material of this graphene coated possesses classification core-shell structure copolymer knot Structure, sulfur/multi-wall carbon nano-tube composite material is kernel, and Graphene is then evenly coated at sulfur/multi-wall carbon nano-tube composite material granule Outer surface become the protection shell of " half cage " shape, make the most lithium sulfides of the product in discharge process be limited in " half cage " In, it is possible to the effectively loss by dissolution of the suppression electric discharge many lithium sulfides of intermediate product；Through the mensuration of elemental analyser, Graphene bag Covering the weight/mass percentage composition of sulfur in sulfur/multi-wall carbon nano-tube composite material is 48.986%.
Using obtained graphene coated sulfur/multi-wall carbon nano-tube composite material as positive active material, according to active substance, Acetylene black, the mass ratio of PTFE are that 80:17:3 is sufficiently mixed, and are vacuum dried 12h, so after being pressed into thin slice at 60 DEG C After be washed into the positive plate (on electrode, the carrying capacity of sulfur is at about 2mg) of a diameter of 15mm.With lithium paper tinsel as negative pole, with Celgard2400 For barrier film, electrolyte uses 1.0mol L-1The 1,2-dimethoxy-ethane (DME) of double (trifluoromethanesulp-onyl-onyl imide) lithium (LiTFSI) With the solution of DOX (DOL) (volume ratio is 1:1), wherein contain 0.25mol L-1Lithium nitrate.At full Ar gas Glove box is assembled into CR2025 type button cell.
As the lithium-sulfur cell of positive electrode, constant current charge and discharge is carried out for graphene coated sulfur/multi-wall carbon nano-tube composite material Electrical testing, graphene coated sulfur/multi-wall carbon nano-tube composite material discharge capacity first under 0.1C multiplying power is up to 1488mAh g-1, reached the 89% of sulfur electrode theoretical capacity.0.2C discharge capacity is 980mAh g-1, 0.5C discharge capacity is 892mAh g-1, 1C discharge capacity is 778mAh g-1, 2C discharge capacity is 645mAh g-1, 3C discharge capacity is 538mAh g-1, The high rate capability of illustrative material is the most excellent, and this is with in three-dimensional cross-linked graphene coated structure and multi-walled carbon nano-tubes The electric conductivity that portion's package action improves composite is closely related；Electric capacity is transferred in 0.1C multiplying power after 50 circulations Amount remains within 848mAh g-1, and maintaining a relatively steady state, capacity attenuation speed is relatively low, its reason It is that the double-coating effect of multi-walled carbon nano-tubes and Graphene effectively inhibits the dissolving stream of the electric discharge many lithium sulfides of intermediate product Lose.
The above experimental result all shows, sulfur/multi-wall carbon nano-tube composite material particle exterior surface is coated with high conductivity equably Few number of plies graphene sheet layer, define intergranular conductive network, particularly reduce sulfur/multi-wall carbon nano-tube composite material The contact resistance that on particle exterior surface, the sulfur of insulating properties causes, improves the active material utilization of material the most very significantly And high rate capability；Meanwhile, " half cage " shape graphene coated layer can adsorb further, stop many lithium sulfides intermediate product, Suppress its loss by dissolution, play the effect of the second weight barrier, effectively improve the charge-discharge performance of material.
It is the most efficient that the preparation method of the graphene coated sulfur/multi-wall carbon nano-tube composite material of this test four has technical process Advantage: the graphene oxide slurry that (1) uses provides and high degree of dispersion few number of plies steady in a long-term can aoxidize stone in a solvent Ink alkene lamella, and this slurry can moistening sulfur/multi-wall carbon nano-tube composite material well, make both reach high uniformity Dispersion and mixing, be self-assembly of three-dimensional cross-linked Graphene porous network, received by sulfur/many walls carbon after being then passed through hydrothermal treatment consists Mitron composite uniformly wraps up in the hole of cross-linked graphene network, forms graphene coated sulfur/multi-walled carbon nano-tubes and is combined The hydrogel post of material, can form Graphene " half cage " shape to sulfur/multi-wall carbon nano-tube composite material the most after drying Cladding；(2) by controlling the temperature and time of hydrothermal treatment consists, the sulfur by higher reducing degree graphene coated/many can be obtained Wall carbon nano-tube composite material；(3) preparation method of this test four does not use toxic raw materials, does not makes environment and personnel health Become harm.

Claims (8)

1. the hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole, it is characterised in that the method is according to the following steps Carry out:
One, Graphene slurry is prepared: described Graphene slurry is made up of Graphene and water, and graphene sheet layer is the most uniform Ground dispersion；Wherein, the water content of this Graphene slurry is 90%～99.99%, the concrete preparation method of described Graphene slurry As follows:
(1) graphite and reducing agent are weighed；Wherein graphite is 1:(0.1～1000 with the mass ratio of reducing agent)；Reducing agent is Vitamin C A kind of or the most several combination in acid, KOH, NaOH, LiOH and ammonia；
(2) graphite oxidation that step (1) weighs is become graphite oxide；
(3) it is 0.01mg mL by the concentration of graphite oxide-1～50mg mL-1, graphite oxide step (2) obtained adds water In, peel off under the ultrasound condition that frequency is 20～100KHz, disperse 0.5～10h, obtain graphene oxide aqueous dispersions；
(4) under conditions of temperature is 4 DEG C～100 DEG C, in the graphene oxide aqueous dispersions that step (3) obtains, reduction is added Agent, under the ultrasound condition that frequency is 20～100KHz, reduction 0.2h～24h, obtains Graphene aqueous dispersions；
(5) the Graphene aqueous dispersions that step (4) obtains is carried out vacuum filtration, or decompression rotary evaporation, or rotating centrifugal Process, form the slurry of thickness, the most again it is carried out dialysis or vacuum filtration washing, obtain Graphene slurry；
Two, prepare sulfur/porous carbon composite, wherein porous carbon materials by activated carbon, Graphene, white carbon black, CNT, A kind of or the most several composition in templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon, sulfur/porous carbon is combined In material, sulfur is 1:(0.02～20 with the mass ratio of porous carbon)；
Three, be (0.02～20) by the mass ratio of the sulfur in the Graphene in Graphene slurry and sulfur/porous carbon composite: 1, general Sulfur/porous carbon composite prepared by step 2 joins to mix in Graphene slurry prepared by step one and is uniformly dispersed, and then will Mixed slurry adds and has in teflon-lined hydrothermal reaction kettle, by after airtight for reactor at 100～220 DEG C of hydro-thermals Reason 1～24h, obtains hydrogel post, rolls extrusion moisture therein, then the washing that is soaked in water after being taken out by hydrogel post, It is dried 1～24h at a temperature of 20～90 DEG C, is ground into powder, then at 20～90 DEG C, be vacuum dried 1～24h, obtain Graphene coated sulfur/porous carbon composite.
The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole the most according to claim 1, its feature The preparation method of the sulfur/porous carbon composite being in step 2 is melted diffusion method, particularly as follows: sulfur and porous carbon are mixed Uniformly it is placed in inert atmosphere holding 1h～24h at a temperature of being heated to 100～400 DEG C, makes sulfur melt and be diffused into porous carbon In hole and outer surface, obtaining sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).
The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole the most according to claim 1, its feature The preparation method of the sulfur/porous carbon composite being in step 2 is sulfur steam completion method, particularly as follows: by elemental sulfur in inertia Being heated to 100～500 DEG C in atmosphere or vacuum environment and be sublimed into sulfur steam, sulfur steam is filled in neighbouring porous carbon, subsequently Condensation, obtains sulfur/porous carbon composite, and wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).
The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole the most according to claim 1, its feature The preparation method of the sulfur/porous carbon composite being in step 2 is sulphur-containing solution infusion process: sulfur is dissolved in Carbon bisulfide, In the solvent of a kind of or the most several composition in benzene, toluene, dimethyl sulfoxide, carbon tetrachloride, ether, chloroform, formed Sulphur-containing solution, adds porous carbon in sulphur-containing solution and impregnates, be subsequently dried removal solvent, make sulfur deposit to the hole of porous carbon Neutralizing on outer surface, obtain sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).
The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole the most according to claim 1, its feature The preparation method of the sulfur/porous carbon composite being in step 2 is chemical reaction method, particularly as follows: porous carbon is joined sulfur In the aqueous solution of thiosulfate or sulfide, dispersion mixing is uniform, makes thiosulfate or sulfide be impregnated into the hole of porous carbon Inside, adds dilute acid soln, makes thiosulfate or sulfide generation chemical reaction, sinks with outer surface in porous carbon hole Long-pending upper elemental sulfur, obtains sulfur/porous carbon composite, and wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20).
6. the hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole, it is characterised in that the method is according to the following steps Carry out:
One, graphene oxide slurry is prepared: described graphene oxide slurry is made up of graphene oxide, water and ethanol, oxidation Graphene sheet layer is uniformly dispersed in graphene oxide slurry；Wherein, the containing of graphene oxide in this graphene oxide slurry Amount is 0.01mg mL-1～100mg mL-1, in this graphene oxide slurry, the content of ethanol is 0.001mL mL-1~ 0.1mL·mL-1, the concrete preparation method of described graphene oxide slurry is as follows:
(1) graphite oxidation is become graphite oxide；
(2) graphite oxide that step (1) obtains is added to the water, peels off under the ultrasound condition that frequency is 20～100KHz, divide Dissipate 0.5～10h, obtain graphene oxide aqueous dispersions；
(3) in the graphene oxide aqueous dispersions that step (1) obtains, ethanol is added, at the ultrasonic bar that frequency is 20～100KHz Disperse 0.5～10h under part, obtain graphene oxide slurry；
Two, prepare sulfur/porous carbon composite, wherein porous carbon materials by activated carbon, Graphene, white carbon black, CNT, A kind of or the most several composition in templated porous carbon, carbon fiber, carbon aerogels, carbide-derived carbon, sulfur/porous carbon is combined In material, sulfur is 1:(0.02～20 with the mass ratio of porous carbon)；
Three, by the mass ratio of the sulfur in the graphene oxide in graphene oxide slurry and sulfur/porous carbon composite be (0.04～ 40) sulfur/porous carbon composite: 1, step 2 prepared joins mixing dispersion in graphene oxide slurry prepared by step one Uniformly, be subsequently adding and have in teflon-lined hydrothermal reaction kettle, by after airtight for reactor at 100～220 DEG C of water Heat treatment 1～24h, obtains hydrogel post, rolls extrusion moisture therein after being taken out by hydrogel post, and be soaked in water washing, At a temperature of 20～90 DEG C, it is dried 1～24h, is ground into powder, then at 20～90 DEG C, be vacuum dried 1～24h, To graphene coated sulfur/porous carbon composite.
The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole the most according to claim 6, its feature The preparation method of the sulfur/porous carbon composite being in step 2 is melted diffusion method, specific as follows: sulfur and porous carbon to be mixed Close uniformly, mixture be placed in inert atmosphere and be heated at 100～400 DEG C keeping 1h～24h, make sulfur melted be diffused into many In the hole of hole carbon and outer surface, obtain sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon be 1:(0.02～ 20)。
The hydrothermal preparing process of graphene coated sulfur/porous carbon composite positive pole the most according to claim 6, its feature The preparation method of the sulfur/porous carbon composite being in step 2 is that sulfur steam completion method, sulfur solution dipping method or chemistry are anti- Ying Fa；Sulfur steam completion method is particularly as follows: be heated to 100～500 DEG C by elemental sulfur and be sublimed in inert atmosphere or vacuum environment Sulfur steam, sulfur steam is filled in neighbouring porous carbon, condenses subsequently, obtains sulfur/porous carbon composite, and wherein sulfur is with many The mass ratio of hole carbon is 1:(0.02～20)；Sulfur solution dipping method particularly as follows: sulfur is dissolved in Carbon bisulfide, benzene, toluene, two In the solvent of a kind of or the most several composition in methyl sulfoxide, carbon tetrachloride, ether, chloroform, form sulphur-containing solution, will Porous carbon adds dipping in sulphur-containing solution, is subsequently dried removal solvent, makes sulfur deposit in the hole of porous carbon and on outer surface, Obtaining sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon is 1:(0.02～20)；Chemical reaction method is: will be many It is uniform that hole carbon joins dispersion mixing in the aqueous solution of thiosulfate or sulfide, makes thiosulfate or sulfide be impregnated into The pore interior of porous carbon, adds dilute acid soln, makes thiosulfate or sulfide generation chemical reaction, at porous carbon hole Neutralize elemental sulfur in outside deposition, obtain sulfur/porous carbon composite, wherein the mass ratio of sulfur and porous carbon be 1:(0.02～ 20)。
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